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May 20

Efficacy of vaccines

If I got three different vaccines, let me say Gardasil, One against pneumonia, one against flu, in a time span of just 3 weeks, can that negatively affect the efficacy of vaccines? 112.198.90.97 (talk) 07:00, 20 May 2014 (UTC)

Sorry, questions calling for medical advice aren't allowed to be answered here. Please ask a doctor or pharmacist. --50.100.193.30 (talk) 07:25, 20 May 2014 (UTC)

We can't give medical advice, but we can direct you to information published in reliable sources. If you are really concerned about yourself, seek a medical professional. If you are interested in the general topic, here is a recent journal article titled "Long-term health effects of repeated exposure to multiple vaccines" [1]. Here's another one titled "Simultaneous administration of childhood vaccines: an important public health policy that is safe and efficacious" [2]. SemanticMantis (talk) 13:40, 20 May 2014 (UTC)

Identifying a bird

Hello. I found a wounded bird and have called the regional bird sanctuary to take care of it. In the meantime, can you help me identify what species it is? It comes from north-eastern Spain.

Picture of the bird.

Thank you! Leptictidium (mt) 07:22, 20 May 2014 (UTC)

A juvenile common starling, I think, but given that you're in Spain, it might be a juvenile spotless starling instead. 2.220.78.158 (talk) 08:14, 20 May 2014 (UTC)

I concur. http://2.bp.blogspot.com/-slZCKJpTRz0/UNZRTfwqfeI/AAAAAAAANVA/eQKRLw5eAwk/s400/Starlings+feeding.jpg 196.214.78.114 (talk) 09:44, 20 May 2014 (UTC)

Projectile dynamics

With no air resistance and perfect elasticity, the simplest approach would say that a ball thrown ahead without rotation on level ground will perform an endless sequence of identical parabolic arcs, but I feel that the degree of friction between ball and ground would have an effect on trajectories after the first arc. Is this so, and if so what would the effect be? What would happen in the limiting cases of the coefficient of friction being 0 or 1?→86.146.61.61 (talk) 12:38, 20 May 2014 (UTC)

The friction with the ground would induce more spin with each bounce, and accelerating the ball from no rotation or less rotation at each bounce would use up some of the forward momentum, so the parabolas would get narrower with each bounce, but remain just as high, given your assumptions, until the spin was such that the ball matched the ground, so rolled perfectly on it with each hit. Of course, in addition to being impossible in the real world, one set of your perfect assumptions are also inconsistent with each other. If it was perfectly elastic, then it wouldn't deform at all when it hit, and would hit for an infinitely short period of time, and thus there would be no friction, either. StuRat (talk) 13:20, 20 May 2014 (UTC)

Perfect elasticity is the assumption, friction is a "feel" that the OP has. I'm not sure if perfect elasticity leads to zero friction, but if it does, then the solutions to the model would just be identical repeating parabolic arcs forever.

As for the claim that "perfect elastic, then it wouldn't deform" -- that depends on what OP means by perfectly elastic. E.g. if the modulus of elasticity is infinite, then no deformation occurs, and contact time (hence friction) is 0. But if the elastic limit is infinite, then even with a small elastic modulus, some sense of "perfect" elasticity is retained, even with positive contact time and friction. My impression is that "perfect elasticity" usually refers to the sense given at Elastic_collision, in which case, I agree that there is no friction, as that would fail to conserve kinetic energy. SemanticMantis (talk) 13:52, 20 May 2014 (UTC)

I actually meant by perfectly elastic that there was no loss of kinetic energy but that some compression was possible on impact - in which case, I would assume that in the case of non-unity coefficient of friction there was the possibility of momentary ground-contact sliding before the next parabola, which would certainly occur if the coefficient was zero, with the threshold value depending on the initial angle of projection.→86.146.61.61 (talk) 14:22, 20 May 2014 (UTC)

If we allow that the ball deforms, then the shape will continue to wobble back and forth into a variety of shapes until it hits the ground again - making the height of the second bounce harder to predict depending on whether or not the ball was already compressed along the vertical axis when it impacts that second time. If it's also spinning, then it's not necessarily a clean, symmetrical shape when it next impacts the ground - so the second bounce will launch it off at some angle that's crazily hard to predict. You can see this in practice if you take a "super-ball" (which is extremely bouncy) and spin it as you drop it - the resulting motion looks chaotic. The trouble is that deformation without energy absorbtion is impossible - and that makes talking about what happens rather difficult! A zero here causes an infinity there! SteveBaker (talk) 16:55, 20 May 2014 (UTC)

However, in this idealized world, we can assume the ball would continue to move in the same horizontal direction, whereas, in the real world, a pebble it hit on one bounce might change it's heading entirely. StuRat (talk) 17:20, 20 May 2014 (UTC)

Chaotic? My experience with a "super-ball" as a child was that there was a predictable trajectory, with alternation (on a smooth level surface): depending on the initial spin and velocity vector, it might retrace a parabola back and forth (ignoring decay from energy loss), bounce along a zig-zag line, or do a short hop, long hop sequence. Without the energy loss, every second bounce would be essentially identical. —Quondum 01:27, 21 May 2014 (UTC)

"the parabolas would get narrower with each bounce, but remain just as high, given your assumptions" Assuming the angle of each bounce remains the same, and given that adding spin uses up kinetic energy as well as momentum, shouldn't we expect the height of each bounce to decrease (until the spin reaches maximum)? Olaf Davis (talk) 10:33, 21 May 2014 (UTC)

No, because only the horizontal component of the motion would be converted to rotational energy. Thus the angle would not remain the same. Consider two tests, one with only vertical motion, which would never slow down, given the assumptions, and one with only horizontal motion, which would start out sliding on the ground but slow down and spin up, until it's spin made it roll on the ground. Now combine those two motions together. StuRat (talk) 13:13, 21 May 2014 (UTC)

Yes, you're right of course. Thanks. Olaf Davis (talk) 15:12, 22 May 2014 (UTC)

You're quite welcome. StuRat (talk) 15:24, 22 May 2014 (UTC)

In the ideal case of no slip, you get a pattern that repeats itself with a period of 2 bounces. The ball initially without rotation starts to rotate after the first bounce and in after the next bounce that rotation vanishes. Count Iblis (talk) 14:35, 22 May 2014 (UTC)

Why ? StuRat (talk) 14:42, 22 May 2014 (UTC)

So, after the first bounce the ball rotates, and we want to find out what happens after the next bounce. Of course, anyone can write down the equations (conservation of kinetic energy right before and after the bounce and conservation of angular momentum w.r.t. the contact point) and solve the equations, but there is a much simpler way to see that the period is 2. You just invoke the fact that the laws of classical mechanics are invariant under time reversal and rotations. If the ball moves toward the right, it will start to rotate clockwise after the first bounce. The time reversed version of this is a ball that rotates counterclockwise and moves to the left which then bounces and loses its rotation. Since there is no dissipation in the no-slip limit, this is what would happen in the real world. Now a ball that moves along the x-axis to the left and rotates counterclockwise (angular momentum points in the negative y-direction) is transformed into a ball that moves to the right and rotates clockwise under a rotation of 180 degrees around the z-axis. So, under both a time reversal and a rotation, the motion stays invariant therefore, the ball will get back its original angular momentum after the second bounce. Count Iblis (talk) 10:33, 23 May 2014 (UTC)

I don't see it. What forces would stop the ball from rotating ? If anyone can solve those equations, please show us your results. StuRat (talk) 19:44, 23 May 2014 (UTC)

Musical instruments

Why do people say it's harder to learn music instruments, the older you get? Isn't this true with any skill? Aren't all skills best learn when young, when the brain is at it's best? People say it applies more to musical instruments but I don't know why. Clover345 (talk) 15:05, 20 May 2014 (UTC)

The first thing that comes to my mind is time. Most people have more responsibilities when they are older, leaving less time to practice. This applies to all skills, of course, but because so much of learning an instrument is muscle memory, without regular practice for months at a time (if not years) it is very difficult to do. OldTimeNESter (talk) 15:43, 20 May 2014 (UTC)

I doubt it's true of all skills, for example, I could imagine some skills that can only be learned once some other discipline is deeply understood and mastered - which might take a long time. Other skills only become fully matured after a lot of practice - so again, being young might make that impossible. I'm sure it's true of many subjects - but I doubt that such a sweeping statement as "all skills" is justified.

I'm also skeptical of User:OldTimeNESter's claim that it's a matter of time. Older people who become unemployed and have to learn a new skill presumably have just as much time in school as a younger person...and retired people often take the opportunity to learn a new skill. Certainly there are skills that are vastly easier to learn when young. Notably, it's well known that a young child can learn new languages extremely easily - just by listening to people speak it in context...that's an almost impossible task for an adult. SteveBaker (talk) 16:38, 20 May 2014 (UTC)

I somewhat doubt the last statement. If I throw you into China, with no dictionary, no relatives, and no English anywhere, you might learn Chinese as quickly as a Chinese newborn. When most adults try to learn a foreign language, they're still mostly working with their native language, which is hardly a fair comparison. --Bowlhover (talk) 17:16, 20 May 2014 (UTC)

• I believe the ability to learn things, from a neurological point of view, falls into the study of neuroplasticity. However, our article does not mention any aging effects on neuroplasticity. However, there are lots of scholarly articles on the subject. See [3] and [4] and [5] for a start, just some random articles I found. --Jayron32 17:24, 20 May 2014 (UTC)

A decade or so ago it was quite noticeable in large public institutions that people older than 50 had trouble mastering new technology, in particular the Internet, and preferred to do things old fashioned way even if it was obviously inefficient. --AboutFace 22 (talk) 17:54, 20 May 2014 (UTC)

I think Bowhover's claim about language is clearly not correct. I immigrated from Poland to Australia with my parents when i was seven years old and picked up the language in about 12 months. 30 years later, my parents, as well as their remaining thick accent, are still not nearly as fluent in English as I am, even though they both work and have English speaking friends. There are definitely language milestones that you automatically reach at a young age which are either very difficult or impossible to achieve later in life. Actually I just found the article Second-language acquisition which discusses this, in particular the section called Comparisons with first-language acquisition. Vespine (talk) 23:36, 20 May 2014 (UTC)

To make the above not completely off topic, I believe there are parallels between learning language and music. Anyone can learn to play a few tunes on a musical instrument, but to become truly "fluent" I think you need to start early. Vespine (talk) 23:38, 20 May 2014 (UTC)

Heh. My ex-wife was born in Australia, but because her parents had arrived only 6 months earlier and spoke next to no English, they very wisely decided not to try to teach her their rotten English but let her assimilate the proper language when she started mixing with anglophone kids. So, her native language is Russian, but she started learning English from around 2-3 years, and that quickly picked up pace once she started school. The upshot is that she is totally bilingual. Her Russian is so good that she has appeared in Chekhov plays, she has coached Australian diplomats about to head off to a Moscow posting, and has been praised by Russian-born people for her eloquence (many have asked which area of Russia she was born in). Her English is so good that when she tells people she was born in Liverpool, they blithely assume she means Liverpool, UK, not Liverpool near Sydney. -- Jack of Oz ^{[pleasantries]} 23:57, 20 May 2014 (UTC)

Clover, I notice that several responders above have correctly identified neuroplasticity as the root phenomena at work in how many skills ares best assimilated at an early age, but have not addressed the finer (and very fascinating) distinction you inquire about as to why the skill in question might be of the type that is especially easier to assimilate by younger learners. The answer to that question lies with two forms of processing which the human brain excels at broadly, but which are constrained and specialized during childhood in a window known as the critical period -- auditory cognition and syntax. Some of the earlier responders also quite correctly noted the link between the exercise of music and that of language; the two share some striking similarities in how the human brain processes them a sensory (and communicative) phenomena -- so much so that evolutionary psychologists and other cognitive scientists have been engaged in strong debate in recent decades in a chicken-and-egg style debate as to which one evolved to its current form first in our evolution into anatomically modern humans, as well as to how much they incorporate the same modules of the human brand and mind. Putting aside the finer points of that debate though, it's clear that there is significant crossover in how music and language are constructed from discrete components (phenomena like notes in music and phonemes in language) which are combined to form structures which can impart complex meaning and sensation that often seem to be far more than the sum of their parts.

I know I've just thrown a lot of different terminology at you with minimal contextualization, so let me tie it all together a little better now. The reason I've addressed the issue incorporating language is that it is the much more heavily studied of the two phenomena in terms of neuroscience and cognitive science broadly (though neurological and psychological studies of music aren't exactly unheard of either), to we understand how the critical period works in language acquisition especially, and some of those lessons can be carried over. One of the great revelations with regard to language in the last century was the formation of the concept of universal grammar -- the notion that all healthy human brains come complete at birth with a language organ that allows us to process language in (mostly) the same way as every other human. However, the brain needs to be "fine-tuned" to the specific rules of the language spoken by those around the child, and this is where the critical period comes in; during this time the child begins to specifically internalize the various rules and distinctions that are the basis of their particular native language(s). This includes a vast number of phenomena, but they can somewhat be divided into two groups -- phonology, the differences between the basic units of sound, and syntax, the rules for combining units of meaning together to make statements that other parties can comprehend. So for example, as regards phonology, a child who grew up speaking only Japanese will have difficulty in making the distinction between "r" and "l" sounds in a language such as English, because their language does not have that distinction; to a certain degree, that will vary between individuals, they just simply will not be able to "hear" that difference, because the auditory-linguistic centers of their brain have already learned to filter it out while specializing on other distinctions that were more germane to their linguistic upbringing. Likewise, word-order and other principles of grammar and syntax, will vary between their native tongue and any language they might try to learn later in life, and these rules are very much ingrained by adulthood as well.

Returning to the focus of your question, music shares many of these principles in common; it has specific sounds which the person who wishes to employ it must be able to distinguish between and produce reliably, and it has combinatorial rules which -- though experts are divided on calling syntax -- govern how these sounds are put together to form their intended meaning. In the context of music of course, the "meaning" is much more diffuse than it is in language -- more likely to instill a general emotional response than a concrete concept, but nevertheless, the order in which the sounds are combined and how they are stressed in relation to one another have a profound impact on how the effect those listening, as in language. And also as in language, the earlier the exposure to these principles of the distinctions between sounds and how they are combined (including the motor control necessary for producing them), the better the chance that the learner will be able process and reproduce these distinctions with finer control. It's worth noting, of course, that there are people who can become quite fluent in a language later in life and others who can learn a musical instrument with a fair degree of skill, but by and large, polyglots and musical virtuosos tend to be exposed to the relevant skills at a very early age.

I hope that answers your question in a basic fashion. I wrote the above in a bit of a hurry, so I hope its basically intelligible. If you have more refined questions along these lines, don't hesitate to ask some follow-ups. If you are interested in reading material along these lines which incorporate the relevant sciences (biological and social) but which are written for a very broad audience with no experience in those fields, I can strongly recommend Oliver Sachs' Musicophilia and Daniel Levitin's This is Your Brain on Music. Both are quite informative without being too heavy in the technical sense and written more elegantly than any of the above. Snow talk 23:10, 21 May 2014 (UTC)

Metric prefix

In Metric prefix it says "An exception is emission rates, which are typically on the order of Tg/yr."

Emission rates of what, where? Anyone know? -- SGBailey (talk) 15:27, 20 May 2014 (UTC)

Carbon emissions (sadly just a redirect to Greenhouse gas). There isn't a really standard unit for carbon uptake or emission. Two common ones from the ecosystem ecology and biogeochemistry fields are kg C/m^2/yr and Mg C/ha/yr. I've personally not seen terragrams actually used much, perhaps because the key fluxes in the global C cycle tend to be on the order of petagrams [6]. As with all metric prefixes, scientists usually use the ones most appropriate for the scale of interest. So we might use kg C/m^2/yr for a forest or town while PgC/earth/yr for the planet. Altogether a weird mention, that doesn't add much. I might edit there a bit later. SemanticMantis (talk) 16:16, 20 May 2014 (UTC)

Gay parenting vs heterosexual parenting

I hope this is the right reference desk to ask this question.

Have there been any systematic studies that compare adults adopted as children by a same-sex couple with adults adopted as children by a heterosexual couple? By 'compare' I mean look at things like IQ, divorce rates, crime rates, rate of mental disorders, etc. I tried to find such a study with Google, but what I found instead was 1) studies which compare children adopted by homosexual parents with children raised by their biological parents, or 2) studies relying on parental self-reports of their children's well-being. 65.92.7.8 (talk) 18:10, 20 May 2014 (UTC)

Given that adoption by same-sex couples is a relatively new phenomenon in most countries (see LGBT adoption#Legal status by country/jurisdiction) I very much doubt that studies exist comparing divorce rates or crime rates for example - it is simply too soon for meaningful data to exist. AndyTheGrump (talk) 18:20, 20 May 2014 (UTC)

This study claims to have contacted and examined a significant number of "adult children of parents who have same-sex relationships". Unfortunately, the author does not compare them to adult children adopted by heterosexual parents, which is what I'm looking for. 65.92.7.8 (talk) 23:49, 20 May 2014 (UTC)

DeBoer v. Snyder has a list of the witnesses called by both sides, and a brief summary of their positions. They did cite actual research, so the article could be a good starting point towards finding those studies. Katie R (talk) 19:58, 20 May 2014 (UTC)

LGBT parenting#Children's outcomes. Short answer: the kids are okay. TenOfAllTrades(talk) 20:29, 20 May 2014 (UTC)

While there's certainly a consensus among academic psychologists that 'the kids are okay', I'm concerned about how this consensus was reached. For example, this study supports the claim that "[a]dopted children thrive in same-sex households" by using parental self-reports of whether their children conformed to "expected gender role behaviour", a method I don't consider to be rigorous or complete. If the consensus was formed from studies such as this, then I don't believe that the consensus is merited. IMO, the only legitimate way to determine whether children raised by a same-sex couple fare as well as children raised by a heterosexual couple is by directly comparing adults adopted as children by a same-sex couple with adults adopted as children by a heterosexual couple, and as far as I can tell such a comparison has not been made. 65.92.7.8 (talk) 23:49, 20 May 2014 (UTC)

See WP:NOTFORUM. This is a reference desk - we aren't going to engage in debate over the merits of adoption by same-sex couples, or over the validity of studies of adoption by same-sex couples. If you wish to engage in such debate, please do so elsewhere. AndyTheGrump (talk) 00:11, 21 May 2014 (UTC)

The OP has done nothing of the sort of "engaging in debate over the merits of adoption by same sex couples." As for questioning the validity of studies, he has only said it in reference to particular suggestions, to alert us that he is still looking for an answer to the question. I regard this as a perfectly reasonable approach, and can see no forum style debate - only an attempt to search for quality references. IBE (talk) 07:59, 21 May 2014 (UTC)

It is fortunate, then, that in the study you refer to (Farr, Forsell, and Patterson, 2010 PDF) the researchers made a point of collecting evaluations from teachers and outside caregivers, as well as from parents. The differences between evaluations by independent individuals and evaluations by parents were small, and not significant for either homosexual or heterosexual adoptive parents. I get the impression, though, that you're going to keep moving the goalposts until you get the answer you want. Per Andy, please go looking for debates elsewhere. TenOfAllTrades(talk) 00:58, 21 May 2014 (UTC)

Agreed. This is descending into a "help me selectively find proof of my preconceived notions" We don't do that here. The OP has been provided ample means to find the information they are looking for. No need to keep this farce going any longer. --Jayron32 01:40, 21 May 2014 (UTC)

I wasn't trying to enter a debate over same-sex adoption, and I'm not sure why Andy thought I was. Nor am I anti-same-sex adoption, as TenOfAllTrades suggests. My original question was, "have there been any systematic studies that compare adults adopted as children by a same-sex couple with adults adopted as children by a heterosexual couple", with the caveat that such comparisons use objective measures like IQ, divorce rates, etc. In reply, TenOfAllTrades directed me to the 'Children's Outcomes' section of the LGBT parenting article, which describes the consensus among academic psychologists that LGBT-adopted children fare no worse than hetersexual-adopted children. But this fact doesn't answer the OP, unless this consensus was formed by comparing adults adopted as children by a same-sex couple with adults adopted as children by a heterosexual couple with aforementioned objective measures (and I really hope it was). Admittedly, the study I mentioned before did better than rely exclusively on parental self-reports, but nonetheless I'm not exactly satisfied even with third-party subjective assessments.

Ultimately, I asked this question because comparing things like the IQ of same-sex adoptees with heterosexual adoptees should be both straightforward in principle and also the most objective way of assessing same-sex adoption, and I'm thus bewildered that such a study has not yet been done. 65.92.7.8 (talk) 01:55, 21 May 2014 (UTC)

Fair enough. But be aware that this is a charged topic, and people are likely to read subtext into your requests and comments, so choose your words carefully, with a mind to how they are likely to be understood. --Jayron32 02:08, 21 May 2014 (UTC)

Thank you, and I'll pay closer attention to my wording from now on. 65.92.7.8 (talk) 02:17, 21 May 2014 (UTC)

Hmmm. I presume that you are aware that you're asking the impossible, or at least the extraordinarily difficult. Same-sex marriages have only been legal – anywhere in the world – since 2001. 'Civil unions' for non-heterosexual couples haven't been around much longer. It has been extraordinarily difficult for homosexual couples to adopt children under any circumstances until relatively recently; many otherwise-civilized countries (or states, within the U.S.) still actively discriminate against non-heterosexuals for the purposes of adoption. Asking for outcomes for adult children – particularly of measures like divorce rate, which may require decades of adulthood to properly assess – isn't reasonable. TenOfAllTrades(talk) 03:14, 21 May 2014 (UTC)

In Canada at least, same-sex adoption has been legal since 1985. It unfortunately took a lot longer for same-sex marriage to be legalized, but to my knowledge gay couples in a civil union have been able to adopt since at least 1985. I also know of at least one study that looked at adult children of homosexual couples, though the study in question was flawed because it compared children adopted by same-sex couples with children of heterosexual couples, not taking into account that children put up for adoption are not representative of the general population. 65.92.7.8 (talk) 04:42, 21 May 2014 (UTC)

Speaking specifically to Canada, those dates do not appear to be correct. The summary and timeline here is linked from our article, and seems pretty thorough. The only thing that happened in 1985 was that Section 15 of the Charter of Rights came into effect, which eventually led to court decisions that expanded the rights of same-sex couples. Legislative changes and court challenges that allowed same-sex couples to adopt trickled in beginning in the mid-1990s. (Near as I can tell, British Columbia was the first province to legally recognize the right of same-sex couples to adopt, in 1996.) The landmark decision came in 1999, with the Supreme Court's finding in M. v. H. that an Ontario law precluding same-sex couples from being considered common-law partners was unconstitutional. This precipitated a massive number of legislative changes to bring an assortment of federal and provincial laws into compliance with the ruling. (Even then, official discrimination against adoption by same-sex couples persisted in some parts of the country: [7].)

Incidentally, from your comment above I'm not sure that you were aware that a civil union is a specific, formally recognized relationship conferring many (or all) of the same rights as – or sometimes legally substituting for – marriage. (In some jurisdictions, a 'civil union' option for same-sex couples has been offered as a sort of 'separate but equal' or 'separate but nearly equal' option that avoids some of the emotional and political baggage of allowing same-sex 'marriage'.) This is in contrast to a common-law partnership – which may have been what you were thinking of – which can be established without any paperwork, just by living together. In any event, most of those court cases in the 1990s dealt with establishing that same-sex couples enjoyed the same right as opposite-sex couples to have their common-law partnerships recognized for various purposes (spousal benefits, eligibility to adopt, substitute decision-making for medical care, etc.). In Canada it then required another six years – with the Civil Marriage Act in 2005 – before same-sex couples were allowed to marry. TenOfAllTrades(talk) 13:00, 21 May 2014 (UTC)

Thank you for correcting me on the timeline of Canadian same-sex adoption, and yes I confused a civil union with common law partnership. 65.92.7.8 (talk) 18:56, 21 May 2014 (UTC)

It would be difficult to prove that IQ has anything to do with it. And a factor that I don't see mentioned here is where the adoptees come from. If the natural parents are troubled, it's not unreasonable to expect the adoptees to be troubled likewise, despite the best efforts of their adoptive parents. ←Baseball Bugs ^{What's up, Doc?} carrots→ 03:36, 21 May 2014 (UTC)

I think that you're absolutely correct about how troubled natural parents can lead to troubled children. A conservative study, which I cited above, tried to 'prove' that same-sex couples raise children more poorly by comparing adults brought-up by same-sex couple to adults with heterosexual parents, despite the fact that adopted children are unlikely to be representative of the general population. So it's not surprising that the study concluded that same-sex couples made worse parents than heterosexual couples. This is actually why I asked this question in the first place: the fairest way IMO of comparing same-sex couples with heterosexual couples is by looking at children adopted by heterosexuals, not children raised by heterosexuals in general. 65.92.7.8 (talk) 04:42, 21 May 2014 (UTC)

Yes, it's an apples and pomegranates comparison. Maybe you've heard the old saying, "Figures don't lie, but liars do figure." Also, those various "rates" are subjective. Kids from theoreticaly model families can end up as serial killers. One quantifiable figure (which Canada's data might go back far enough to provide) would be what proportional percent of adult homosexuals were raised by opposite-sex parents as opposed to same-sex parents. ←Baseball Bugs ^{What's up, Doc?} carrots→ 04:51, 21 May 2014 (UTC)

Why would that be an interesting figure? I would for example expect that bisexual or homosexual children raised by same-sex couples would be "out" much earlier and without much hassle, while children raised by opposite-sex couples would encounter the "usual" anxiety. There is no objective way to seperate sexuality from upbringing in an adult, IMHO. And another point to the discussion: Why would you even require IQ score (or some of the other measures mentioned above) to be equal? Is IQ suddenly a magically marker for "good upbringing"? Are children with lower IQ somehow "bad"? Remember, IQ does not equal general intelligence, and high IQ score (or intelligence) do not mean that you will lead a happier live or be more or less productive under all circumstances. These are really murky waters. Heterosexual couples are allowed to raise their children the way they want, why should homosexual couples have to conform to some form of "predescribed" upbringing? The children should not be actively harmed, in that I do agree, but that is a very different point than requiring "equal" upbringing. To clarify that point: No one is for example requiring the (heterosexual) Hillbillies to move into the Big City because the education there would be much better for their children. --TheMaster17 (talk) 14:30, 22 May 2014 (UTC)

And another thing I just realized: Would you find it really worrisome if gay parents would raise more gay children? After all, heterosexuals are also raising more heterosexual children at the moment. Neither of those is bad, or do you disagree? --TheMaster17 (talk) 14:32, 22 May 2014 (UTC)

May 21

What type of tree is this?

The image is a partial screen shot of a scene of Foyle's War which is set in Hastings, UK. The scene takes place outside a manor. A closer shot of the trees shows that they have fairly smooth bark between those knots that you see on the trunks. The scene is set in February which I'm guessing is why there are no leaves. So, what type of trees are they and are they trimmed like that on purpose to be more ornamental? Thanks, Dismas|^(talk) 07:04, 21 May 2014 (UTC)

Those are Common lime (tilia × europaea) trees, called Linden trees in the US. They are deliberately cut that way partly so that they are size controlled and some people (me included) like the knobbly aged appearance when it has no leaves. You are right about the season, in summer the tree grows shoots of up to 3 feet long giving a slight lollipop appearance to the tree. The process of pruning the shoots back each year is called pollarding. Richard Avery (talk) 07:32, 21 May 2014 (UTC)

Thanks! Dismas|^(talk) 08:24, 21 May 2014 (UTC)

Pick proof lock

On my new house I would like to install a lock on the door that cannot be picked even be a professional locksmith. Does such a lock exist. I have heard about electronic locks that use a small keyboard built into it, then you make a password and then enter in your password to open the lock, and also another lock that uses your fingerprint. Can these be picked? And what happened when the battery runs out are you locked out forever? Also the one that uses your fingerprint is is possible for someone to extract your saved fingerprint from it?--Interestingusername123 (talk) 08:37, 21 May 2014 (UTC)

On Mythbusters, they managed to get into a couple of fingerprint locks quite easily. Electronic ones with no key backup require electricity to open. I don't think there's an "unpickable" lock. Keyboard locks are good, but they can wear in a pattern of the most used keys, which makes it easier to guess. 217.158.236.14 (talk) 09:07, 21 May 2014 (UTC)

Easier to guess...maybe...but not necessarily! If you have a single 4 digit code with no repeated digits then the wear pattern says what the four digits are...but not in what order - that would result in the bad guy having to try 4x3x2=24 patterns. That's way too easy! But with a 6 digit code (no repeats), he's got to go through 6x5x4x3x2=720 patterns. My wife and I each use a different 6 digit pattern - which (I suspect) cover all of the ten buttons on the pad...so all of the buttons wear out more or less equally fast and the bad guy is out of luck! If you really must have just one 4 digit code - then at least change it every few months to even out the wear on the buttons! SteveBaker (talk) 14:08, 21 May 2014 (UTC)

And after a change or three, they will forget the curent code and, wait for it, need a locksmith. Oh the irony. - ¡Ouch! (^{hurt me} / _{more pain}) 11:49, 22 May 2014 (UTC)

I once read about a door key lock which had only I, V and X keys in an attempt to avoid this problem. I can't find any online references though, so I guess it didn't catch on. 2A01:E34:EF5E:4640:E572:F28:C9E1:6456 (talk) 07:01, 22 May 2014 (UTC)

Clever! But you end up with much longer key sequences to remember...so I guess it's diminishing returns. Incidentally, last night I took a look at my door lock - and while there are actually three keys that are not in either my wife's or my key code - I can't see or feel any difference between those and the ones that get used half a dozen times a day. The buttons are all very smooth - I'm guessing they're made that way for precisely this reason. I think the "smooth key" exploit is a bust for decently made digital door locks. SteveBaker (talk) 16:47, 22 May 2014 (UTC)

I was also reminded of a key lock we had on a gate at work that used multiple simultaneous button presses (2 then 4 then 3 and 5 together). Using "chords" like that increases the number of combinations a LOT and also makes it vastly harder to use the "worn keys" trick to make brute-force searches work. SteveBaker (talk) 16:50, 22 May 2014 (UTC)

I'm reminded of this story: Ouch! William Avery (talk) 10:55, 21 May 2014 (UTC)

If this isn't just a case of "I want to start a forum chat about this topic because I'm bored", then you probably should talk to a professional to figure out what your security needs actually are. Note that most burglars aren't picking locks anyway—they're breaking a window or using a short prybar to separate the door and lock from the door frame. Making one small component harder to break doesn't magically secure your entire house; having a totally unpickable lock doesn't protect your valuable goods from a chainsaw through the wall attack. TenOfAllTrades(talk) 11:39, 21 May 2014 (UTC)

In a lot of places, people don't even lock their doors. If the house is far enough away from any other houses where nobody would hear a window breaking, there's not much use in locking the doors. Dismas|^(talk) 12:28, 21 May 2014 (UTC)

You should make a room of your house easy to enter, such that you can't easily enter the rest of your house from that room. You put some stuff there that looks like valuable items that are clearly visible from the outside but in reality they are worth nothing. E.g. fake jewelry, fake laptops, smartphones etc. Smartphones with GPS tracking that are configured to automatically take pictures and send them to you by email are also useful. Install motion detectors in that room such that the police is automatically called when anyone enters that room. This can only be switched off from outside the room allowing you to enter the room without problems. Count Iblis (talk) 12:42, 21 May 2014 (UTC)

Not necessarily good advice. Our police Crime Prevention unit advised that internal locks were rarely worthwhile as once someone is inside they can easily break almost anything being out of site. Evidently the repair bill often outweighs the value of items taken. -- Q Chris (talk) 12:50, 21 May 2014 (UTC)

My God—that's brilliant! I should sacrifice one whole room of my house, filling it with valuable-looking but useless crap and the security system from an action movie, forever, on the off chance of attracting a burglar who might otherwise have walked right on past. This sort of nonsense is why you should demand references at the Reference Desk. TenOfAllTrades(talk) 13:12, 21 May 2014 (UTC)

Yeah - I agree. It's like the old joke about how fast you have to run to get away from a charging grizzly bear...faster than the guy standing next to you! All you really need is better security than your neighbors - and that's usually very easy. Security cameras (even fake security cameras), digital locks and good outside lighting (front and back of the house) are enough to make the bad guy look at your house, and one further down the street - and figure that the other house is an easier target. SteveBaker (talk) 14:14, 21 May 2014 (UTC)

Is that assertion based on crime statistics, though? Or is it just a hunch based on a general opinion you've formed about criminal psychology?

To confound the statistical research, the FBI's nationwide Uniform Crime Report, which is the authoritative nationwide crime statistics database in the U.S., defines burglary as unlawful entry. Many local jurisdictions define separate crimes for breaking and entering and larceny and burglary. If a door is unlocked, the FBI considers home-invasion and theft to be be "burglary", but some states do not. If a door is locked, and an entrant picks the lock,... some places consider that burglary, and others do not. American law - and therefore, crime research in the United States - is about fifty times more confusing than it seems at first glance. Nimur (talk) 15:27, 21 May 2014 (UTC)

And if they just break down the door? 24.5.122.13 (talk) 21:27, 21 May 2014 (UTC)

In my state, it depends why they broke down the door. In other words, it is burglary if they broke the door with intent to commit additional crime, specifically intent to commit larceny. Contrast, for example, a case where some fool breaks down a door and promptly leaves: they have probably committed felony vandalism. Obviously, a criminal court needs to convict a defendant, i.e. by proving intent before we consider them guilty of this type of crime. Nimur (talk) 22:21, 21 May 2014 (UTC)

That's right, but then many burglaries are committed by people in the neighborhood who are familiar with the owners of the house, they know when they are on vacation and are then not fooled by such measures. Also you explain, physical security is problematic from a collective point of view, you depend on your neighbor's home having less security. A honeypot strategy makes more sense from a collective point of view. If burglars know that they'll get busted when they succesfully steal something (the problem being caused by what they steal), they won't attempt to break into a house in the first place. Count Iblis (talk) 16:01, 21 May 2014 (UTC)

It depends on what you mean by "pickable". That term normally means opening a lock without destroying it, which is important for say, spies, who don't want to give away the fact that they were there. Making a lock that must be destroyed to open it should be possible, although the lock could be replaced by an identical one, given enough time, so cameras that send images to a remote, secure location for storage might be a better option. StuRat (talk) 13:04, 21 May 2014 (UTC)

I think a bunker would deter most criminals but it is expensive, perhaps a safe room might do the job okay? :) Dmcq (talk) 13:28, 21 May 2014 (UTC)

If you are in the USA, you could go to the library and look at back issues of Consumer Reports at your local library. Consumer Reports rates locks (among other things). The good part is they're impartial and about as proficient as you could expect from generalists. The bad part is that since they're generalists, they don't get into subtle differences between products that would be important for a professional in a particular field. Jc3s5h (talk) 13:52, 21 May 2014 (UTC)

The digital locks that I have (which cost ~$80 in HomeDepot) are "unpickable" by mechanical means because there is no keyhole or other means of getting to the mechanical stuff. The keypad can be programmed to use any number of codes of either 4 or 6 digits - and you can do things like creating a time-limited code that only works for one day (so if you have someone calling at the house to do some work, they can let themselves in - but their code expires). It's handy to create temporary codes for visiting friends and such too.

The thing is indeed battery operated - and when the battery dies, you're certainly locked out. The machine uses a small electromagnet to engage a clutch when you enter the correct code - then you can turn the knob to open the door. So the battery only has to power the pad and the magnet...and only then while you're actually opening or locking the door. I change the battery once a year (when I change the smoke detector and thermostat batteries) - but I know I forgot one year and the battery was still just fine after 2 years of use. When the electromagnet isn't engaged, the door knob just spins uselessly because it's not physically connected to anything.

The only way to get in (short of smashing down the door) is to enter one of the right codes...which would take a LONG time to do by trial and error if you use a 6 digit code...but maybe the bad guy could guess it if you used your birthday or something stupid like that! I suppose there might be some incredibly clever thing you could do with magnets to cause the clutch to engage without the lock's own electromagnet...but the actual mechanism is buried in a lot of metal, a couple of inches behind the faceplate...that seems unlikely.

Fingerprint locks are relatively easy to fool if the bad guy can lift one of your fingerprints (eg from the door handle!)...that's been demonstrated many times and there are lots of websites showing you exactly how to do it.

Nothing is ever going to be perfect - but since it's so insanely easy to learn to pick or destroy the standard cylinder locks that 99% of people have, anything is better than nothing. IMHO, unless someone is specifically out to get **YOU**, your locks only have to be more secure than your next-door neighbor because the bad guys will always take the softer target. But unless you have bars at the windows and a sturdier-than-normal garage door, smashing a window is always going to be easier than getting past a digital lock. SteveBaker (talk) 14:02, 21 May 2014 (UTC)

I hope you've got a good one! There's quite a lot of simple hacks for digital door locks published on the web. The best ones I've seen involve inserting a wire strategically through the space beside one of the keys so it makes a contact inside which opens the lock, they have competitions with different locks to see how quickly people can crack them. It is a bit disturbing to see how easy it is to get lock picking equipment. And without even picking the lock they have things like a flexible arm with a camera and gripper st the end you shove through a letter box and control with a joystick to open doors. Dmcq (talk) 16:24, 21 May 2014 (UTC)

My door lock has a solid sheet of deformable plastic between the buttons and the switches beneath - I think it's there to stop water from getting in - but it might also be to stop the exploit you describe. Also, US houses don't have letter boxes...we have to walk two blocks to the array of mail boxes to get our post! SteveBaker (talk) 16:41, 22 May 2014 (UTC)

Being permanently locked out of your house if the battery dies is still unacceptable, IMHO. If you have multiple doors with independent battery power, it's less of a problem. But, if you have an apartment with only one entrance, I'd expect it to work on either battery or mains power, and to beep loudly when the battery runs low (using mains power to make the loud sound, so it doesn't run the battery down even quicker or use the short, high pitched sound that smoke detectors make when their batteries are low, which is notoriously difficult to track down). StuRat (talk) 16:49, 21 May 2014 (UTC)

Why do Britishes say mains power? Mains are big. The wire going into your house isn't even thicker than your water meter pipe. By that logic you should have mains dial tone and mains cable TV. Sagittarian Milky Way (talk) 00:59, 24 May 2014 (UTC)

I'm not a Brit, but I do like the expression "mains power", as the US equivalent is ugly: "power derived from plugging into the wall outlet". And I've noticed "water main" is used to mean any clean water pipe outside of buildings, not just the "main" ones. StuRat (talk) 04:01, 24 May 2014 (UTC)

You're only locked out from one door if the battery fails - my house has two doors and a garage door - all with digital locks. It's a stretch to imagine all three of them failing! Apartments are a different deal - I agree. But with at least a 2 year battery life, it's really not a big deal to change them once a year along with the thermostat and smoke detector batteries. SteveBaker (talk) 16:41, 22 May 2014 (UTC)

Practically speaking, I think most people want locks that can be picked so that it doesn't cost too much to lose the key or other access method. As long as the lock is harder to pick than it is to break in another way, what difference does it make? The crook will still get in. Wnt (talk) 21:28, 21 May 2014 (UTC)

The beauty of digital locks is that there are no keys to lose. You might forget the code - but it's unlikely because you use it several times every day. My door lock also has a 'master code' with a dozen or more digits which I keep carefully buried in an obscure web page somewhere online! I think I can open a regular cylinder lock using a decent set of picks a little faster than I could reliably break it open...but perhaps an expert at the "hammer a screwdriver into the keyhole" might do better. Breaking the digital lock seems like it would be insanely difficult. You could smash the outside part completely - and still be no closer to getting in. If the door itself is reasonably sturdy and you used those really long bolts to hold the striker plate to the door frame - it would be hard to break the door down by kicking it. So I think the difference between "pick-time" and "break-time" is less important than how long the "break-time" is. IMHO, digital locks are better because they are harder to break - not just because they are harder to pick. But in the end, the ultimate question is "Is it easier than smashing a window?" ...and that's where you hit the limits of what's worth doing with the door lock.

Personally, I just like not having to carry a key - and never being accidentally locked out! SteveBaker (talk) 16:41, 22 May 2014 (UTC)

I got plenty of nothing. Bus stop (talk) 17:15, 22 May 2014 (UTC)

I asked a hardware store owner about this question. He said some inexpensive widely sold locks have cylinders he could pick in a few minutes, typically, but with luck or extreme skill it might take only seconds. He charges 7 dollars to pick a lock when it is brought in and the customer wants it rekeyed but doesn't have a key. It is an every-day job. Some expensive security locks would be hard to pick, such as the Medeco. But he said he could drill out the cylinder even on such a lock in a short while. He also commented that if he wanted to open a door with an absolutely pick-proof lock, it would be little challenge to use a battery powered drill and saw to cut around the lock. Or should we posit drill- and saw- proof door and walls? Edison (talk) 04:15, 23 May 2014 (UTC)

One also has to take into account the potential problem of the lock failing and you becoming locked into your home as a result. Especially if this is prone to happening in an emergency situation like a fire when you need to get out asap. Count Iblis (talk) 10:36, 23 May 2014 (UTC)

That's a non-issue. The battery doesn't drive a motor that retracts the bolt as you might, perhaps, expect. Instead, the handle on the inside of the door is manually operated and works even if there is no battery in the lock mechanism - just like any 'conventional' lock. The way the bolt is retracted from the OUTSIDE of the door is also a rotary knob - but there is a clutch mechanism that disconnects the outside knob from the bolt mechanism unless the battery has enough charge and you entered the correct code. So opening the door from the outside requires you to enter the correct code, then the clutch engages and you can turn the knob until the door opens. The electromagnet that holds the clutch releases after a few seconds whether you open the door or not. SteveBaker (talk) 20:45, 23 May 2014 (UTC)

With all this discussion on picking locks, don't forget that punching the pins out of the hinges (with an outward opening security door) is often an easy option, and not often protected against! 122.108.177.30 (talk) 07:04, 24 May 2014 (UTC)

LASIK surgery

Is lasik surgery done when you are consious? Is it painfu Zonex shrestha (talk) 10:08, 21 May 2014 (UTC)ljonesh

[According to lasik.com|http://www.lasik.com/articles/common-lasik-fears], the patient is awake but they're given numbing eye drops and sometimes a mild sedative. They say " some patients notice mild discomfort". Olaf Davis (talk) 10:25, 21 May 2014 (UTC)

My wife recently had it done - they used sedatives - but she was conscious though it all. She said that it was a bit scarey - but not painful - although her eyes felt 'gritty' and a bit sore afterwards..."kinda like if you'd been awake all night" was how she described it. She told me that the worst part was the smell. A representative of the company that makes the equipment happened to be there and we got chatting after I mentioned that we own a couple of laser cutters at home. So I got a ringside seat and he talked me though the whole thing on a couple of large-screen TV's they have in an adjacent room with a window overlooking the Lasik suite.

There is evidently more than one way to do this - so I can only describe the procedure they used for my wife - but maybe it'll be of some help. If you're squeamish - skip the next paragraph!

First they have to remove the outer layer of the eyeball so that they can get at the lens beneath. So the laser cuts out an 8mm diameter circle of the outer membrane leaving a gap at the top (this takes about 3 seconds) and then cuts out a thin channel, maybe a millimeter long off to the side. Then it switches focus so it's delivering energy beneath the surface of the membrane and scans back and forth over the circle in a series of close-spaced horizontal lines, making the fluid underneath vaporize (maybe 10 seconds) - the resulting gasses vent through the tiny channel they made earlier. The bubbles this produces gradually detach the circle of membrane from the underlying lens, leaving it connected at the top. The doctor then lifts the resulting 'flap' out of the way. Next, a different laser scans across the exposed lens surface shaping it into the new form (maybe 30 seconds) and then the flap is dropped back on top of it and gently smoothed out with a small plastic tool to remove air bubbles. Once all the bubbles are gone, the flap stays 'stuck down' by the surface tension of the fluids under there - so it doesn't move around or anything like that.

Then you're done...the whole thing was over in 10 minutes...it would have been faster but the fancy height-adjusting chair that she sat in had developed a problem and they had to reboot the chairs' computer to fix it(!!).

The moment the procedure was over, her vision was instantly hugely improved. They gave her a very quick eye-test to be sure everything worked out OK. She was given sedatives to take through the rest of the day - and some transparent goggles to wear that are just there to ensure that you don't accidentally forget and rub your eyes. (That's really important during the first 24 hours because they don't want you to displace that membrane flap until it starts to heal.)...for most of the rest of that day the sedatives kept her asleep...over the next few days, up to maybe a week, she had a complicated schedule of three different eyedrops to use at different times of the day. Throughout that time, her eyesight got slowly better and better (although it was vastly, amazingly better right after the treatment). After a week or two, she was down to just one over-the-counter eyedrop that just added lubrication. She was still using those a couple of times a day more than a month later. She had to go for checkups a half dozen times over the next few months - they just gave her an eye test and that was that.

SteveBaker (talk) 13:39, 21 May 2014 (UTC)

This description (in small font) appears to confuse a few terms and parts of the procedure, described at LASIK. The lens of the eye is not involved at all – it is the cornea that is reshaped, by ablative removal of tissue at a shallow depth inside the cornea. The initial lifting of a "flap" consisting of the surface of the cornea (along with epithelium) is done with a mechanical blade. At no stage do they affect anything more than about 30% into the thickness of the cornea, thus leaving the remainder of the depth of the cornea intact. —Quondum 14:23, 21 May 2014 (UTC)

The technique using a blade is very obsolete. These days, "bladeless LASIK" is the thing. And heck, please don't call me a liar - I was there and watched the whole thing - my description of how they removed the flap is what I saw, there was no blade involved and the entire procedure was explained to me by one of the guys who works with these machines every day. I saw the flap being cut, the bubbles being made and the membrane gently separated by the expansion of those bubbles (not "cut"). You're correct about the cornea rather than the lens being involved...it's actually forming the cornea into a corrective lens - so we need to be a little more careful than I was about that. The bladeless approach is better for many reasons - less risk of infection from the blade, less cornea being removed (because the laser-created flap is precisely the thickness of the membrane) - and less of the cornea has to be removed to form the lens because you don't have to fix the problems that cutting the cornea with a knife caused. Also, the laser is vastly more accurate than the blade - so the shape of the flap is more accurately formed and the resulting flap fits precisely back into the hole that the laser made - so recovery time is faster. SteveBaker (talk) 16:15, 22 May 2014 (UTC)

The article mentions both methods of creating a flap; my own experience is a little dated. I opted for PRK to avoid the corneal flap and consequent weakening of the cornea. There are many variations on this general procedure; your use of the term membrane suggests a variant of the Epi-LASIK procedure, in which only the epithelium (i.e. a very thin flap) is temporarily lifted before laser ablation. —Quondum 21:30, 24 May 2014 (UTC)

Personally, I would stick with spectacles rather than risk an unnecessary surgical procedure see: http://www.lasikcomplications.com/ Richerman (talk) 21:52, 21 May 2014 (UTC)

Yeah - my wife and I worried about that - but her eyesight before the procedure was truly terrible. Glasses did a poor job of correcting it because when lenses are powerful enough to correct her vision, the distance of the lens from the eye becomes super-critical and she never got good results with glasses. She was badly astigmatic too - and contact lenses that correct astigmatism tend to gradually rotate and when they do, everything goes blurry until you blink a few times and everything goes sharp again. Her contacts needed to be so asymmetrical that even blinking didn't always get them rotated back the right way. That's really a bad thing when you're driving! For her, LASIK was a truly amazing thing. Well worth the (very, very small) risk of problems with modern LASIK systems. My eyesight is reasonably well corrected with a combination of driving glasses and reading glasses - so I won't be getting LASIK anytime soon. SteveBaker (talk) 16:15, 22 May 2014 (UTC)

Synovial fluid agonist?

Can one raise it's levels of Synovial fluid by Nutrition for example? thanks Ben-Natan (talk) 16:23, 21 May 2014 (UTC)

Hyaluronan, a major component of synovial fluid, is a potential supplement. Apparently it is such a large molecule that the body has a hard time absorbing it. Injections into the joint are recommended. There is also chondroitin and glucosamine, although I don't believe these supplements directly increase synovial fluid. Justin15w (talk) 22:33, 21 May 2014 (UTC)

Identification of an Electronic Componenet

Various forms of Variable capacitor showing a compression trimmer at bottom center.

the following component was sold to me as 50 picoFarad Variable capacitor. but i am not sure about its variable & fixed legs. i also do not know how to connect it to the circuit for varying capacitance. front & back picture is attached. please help. picture link: https://drive.google.com/file/d/0B6hyDm8QXr34M2tnaS1hVDJPTkU/edit?usp=sharing https://drive.google.com/file/d/0B6hyDm8QXr34NXhTOEtmVUU4Rjg/edit?usp=sharing https://drive.google.com/file/d/0B6hyDm8QXr34dVNmMWJGcms3emc/edit?usp=sharing — Preceding unsigned comment added by 223.223.151.164 (talk) 19:07, 21 May 2014 (UTC)

Your pictures are unsharp but it looks like two compression trimmer capacitors side by side. Such components are used for one time settings in oscillator and tuning circuits. The tuning screw should be connected to rf ground; this is so the effective capacity does not change when you touch it with a screwdriver. A weakness of the compression trimmer is that there is no easy way to show the variation in capacity on a calibrated scale such as for manual tuning of radio stations. 84.209.89.214 (talk) 13:43, 22 May 2014 (UTC)

Eye scream [stolen eyes and retinal scans]

There's a news story linked above about a man who had part of his finger chopped off by criminals as a result of owning a car with a fingerprint-activated ignition.

This got me thinking about those retinal/iris scanners that seem to have gone beyond the realms of sci-fi in recent years. Has there yet been a confirmed real-world case of someone having their eye gouged out, or even being decapitated in order that criminals might gain access to <whatever> by fooling the scanner?

I suppose that there are more people in the world who'd be prepared to cut off someone's finger than would take someone's eye, with regards to the squeamishness factor of the thing... --Kurt Shaped Box (talk) 20:33, 21 May 2014 (UTC)

Violent criminals are NOT known to be squeamish about much of anything -- but the obstacle here is more practical, in that an eye is more likely to be damaged in the process of being gouged out, which would make it unusable. 24.5.122.13 (talk) 21:23, 21 May 2014 (UTC)

Plus of course the fact that it takes more effort to gouge out an eye without completely destroying it than to cut off an intact finger. 24.5.122.13 (talk) 08:46, 22 May 2014 (UTC)

Trouble is, they could have gotten much the same result by pushing the persons finger into a gummy-bear and using that to start the car...but hey, if they were smart, they'd be rocket-scientists and not criminals. Selling the car, complete with the dismembered finger needed to start it, is going to be difficult! It's really ridiculous to use fingerprint scanners - they are so easily fooled, and they cause problems like this one. Retinal scanners are a little better - but their usability is a major hassle. Biometrics in general are not a great way to do security. SteveBaker (talk) 16:02, 22 May 2014 (UTC)

Wouldn't the fingerprint on the gummy bear be backwards though? Would that still work? --Kurt Shaped Box (talk) 22:28, 22 May 2014 (UTC)

Hammering a nail

Okay, a fairly simple question, yet one I still cannot understand. According to Newton's laws of physics, if I hammer a nail with a force, the nail will also produce an equal and opposite force to oppose mine. I understand that since the forces are on two separate objects the forces do not simply "cancel out;" however, if the magnitude of the force I apply is equal to the magnitude of the force applied by the nail, why then am I still able to hammer a nail into a piece of wood? I was not sure if the answer was simply "my force is greater than the force required to puncture the wood," or if it was a more scientifically-based answer. Thanks for any input. 23:29, 21 May 2014 (UTC) — Preceding unsigned comment added by 74.15.7.68 (talk)

When the hammer strikes the nail, the nail exerts a force on the hammer and the hammer exerts a force on the nail. ( Note: these two forces are indeed equal in magnitude and opposite in direction. However, they are applied to two different bodies, and can not cancel each other ). The force exerted by the hammer on the nail is not initially cancelled by anything: it simply accelerates the nail. Indeed, the nail was stationary before, and now it's moving forward, relative to the observer. The force exerted by the nail on the hammer decelerates the hammer, slowing it down a bit. After a while, the velocities of the nail and the hammer equalize, and they now move together. As the nail progresses into the wood, the nail exerts a force on the wood, and the wood exerts the force on the nail. This force is then (mostly) passed by the nail onto the hammer, decelerating both the nail and the hammer further, until they both stop. Does this help? --Dr Dima (talk) 01:02, 22 May 2014 (UTC)

Well, think of it this way: What would happen if you tried to use a wooden board to hammer the blunt end of a nail into a steel hammer? The forces are equal, but what the force does to the adjacent object can vary. Wnt (talk) 02:13, 22 May 2014 (UTC)

The forces are equal, but the same force has a greater effect on the nail than it does on you because:

1. You're much heavier than the nail, and F=ma

2. The nail is narrower, so the force per unit area (pressure) exerted on the wood is much greater than the force exerted on your hand. --Bowlhover (talk) 05:07, 22 May 2014 (UTC)

Newton's laws obviously apply here - but they don't really help very much in the explanation of what's going on.

If you hit a piece of wood directly with a hammer, it'll leave a shallow dent about the same size as the diameter of the hammer head. When you hit a nail into wood, it too makes a "dent" in the wood - this time it's only just the diameter of the nail - but much deeper. In both cases, the energy that you applied to the hammer is absorbed by the wood as it is compressed, distorted and torn...all that really changed was the shape of the hole and how the wood fibers had to be bent and broken in order to conform them to the shape of the impacting object.

A nail is a clever little "machine" that takes a force that's distributed over a broad, flat surface and concentrates it at the tip to drive a very thin object deeply into the wood. What actually makes the hole in the wood is the amount of energy applied to each little wood fibre. The hammer head by itself has to share the available energy between a heck of a lot of little fibers - but the tip of the nail only touches a very few of them - so the amount of energy applied to each fiber is HUGE. Consider the head of a typical hammer is probably 4 square centimeters - the tip of a nail might be maybe one square millimeter...so the amount of energy applied to each wood fiber is maybe 400 times more! In fact, the nail mostly pushes the wood off to the sides of the hole rather than bending them downwards as the hammer head would - and that stretches the fibers and the resulting extra tension is what allows them to grip the nail and stop it from falling out again.

SteveBaker (talk) 15:56, 22 May 2014 (UTC)

May 22

Quitting Smoking and Weight Gain

Not a medical question, just can't seem to find an accurate answer and am curious. Disclaimer out of the way - gaining weight is associated with quitting smoking. From what I've read, thus far, I've heard that this is due to three different things: smoking increases metabolism, increased eating, changes in gut flora. The common amount of weight gain is supposed to be around 10 pounds - but I've also read that that number isn't useful for individuals since some smokers gain a much larger amount that skews it. So, here's my question (I'm hoping that there is some reliable data to actually look at): what is the primary cause of this weight gain, is it harder to reverse gain after quitting, what determines who will gain a lot as opposed to a little? Essentially, how does this all work? --back to the disclaimer: when I can't sleep, I just google random things that pop into my head, this happened to be one of those things; but, since I can't find any really rock solid details, now I'm even more curious. Thank you for any help (sorry for the ridiculously long question):-) Phoenixia1177 (talk) 08:00, 22 May 2014 (UTC)

This recent review article says "The mechanism of weight gain includes increased energy intake, decreased resting metabolic rate, decreased physical activity and increased lipoprotein lipase activity." (and also lists several complicating factors, e.g. age, genetics, heavy smoking, etc.) [8]. This google scholar search has many relevant articles, some seem are more focused than the general review [9]. SemanticMantis (talk) 13:52, 22 May 2014 (UTC)

I suspect that the sense of taste plays a role, too, although that's a bit difficult to quantify, so less likely to be studied by science. I certainly know that for me, a nonsmoker, the smell of cigarettes makes me lose my appetite. Interestingly, it's not the tobacco itself, as pipe tobacco, which is relatively pure, doesn't cause this effect. Specifically, I suspect it's the ammonia they add to cigarettes, to draw out the flavor, that turns my stomach. I once bought a candy bar from a vending machine and immediately spit it out as inedible. I went back and looked at the rest of the vending machine to find they had cigarettes in there ! StuRat (talk) 14:00, 22 May 2014 (UTC)

• There may be multiple factors here, but probably one of them is serotonin. Nicotine is known to increase the release of serotonin in the brain, and one of the effects of serotonin is to suppress appetite. So quitting smoking means less serotonin, which means more appetite. Looie496 (talk) 17:34, 22 May 2014 (UTC)

Another factor is that some people eat sweets (candies) to distract themselves when they have cravings; the additional energy intake is what causes weight gain.

Genetic engineering to alter genes

You can add genes to cells with a vector such as a virus. How do you remove or alter existing genes? [10] 203.45.159.248 (talk) 08:40, 22 May 2014 (UTC)

Well, when adding genes to a specific location, you would make a vector containing the gene of interest (plus a selection marker) flanked on either side by a stretch of DNA that is the same as the genomic region you're planning on inserting the gene into, this to facilitate the homologous recombination. Now imagine doing the same, but instead of the gene of interest, you put nothing in between the flanking genomic regions. You would remove from the genome any sequence that is in between the flanking regions. Also note that it's not necessary to remove the whole gene of interest from the genome to knock out the function, just the first exon or so is normally enough. Now, in practice you wouldn't have nothing in between your flanking regions, you would still introduce something to help with selection, like an antibiotic resistance gene, or a fluorescent protein. Note that this is the traditional way of doing things, these days with things like CRISPR the methods can be different, though the basic principle is the same. Fgf10 (talk) 08:52, 22 May 2014 (UTC)

I have -4 power in my left eye but almost neutral in my right eye. If i stop to use the spectacle then what problem may arise ?

I have -4 power on my left which is in X-axis in some degree rotation due to which my contact lens always move when i blink my eyes and everything go blur. What kind of contact lens is suitable for me? — Preceding unsigned comment added by Zonex shrestha (talk • contribs) 09:40, 22 May 2014 (UTC)

Wikipedia's reference desk will not answer requests for medical advice. See an eyecare professional, who can answer this question. --Jayron32 09:42, 22 May 2014 (UTC)

We also do it gently, so as to avoid putting people off. IBE (talk) 02:49, 23 May 2014 (UTC)

See here. Count Iblis (talk) 11:20, 22 May 2014 (UTC)

If your lens is designed to correct astigmatism at all, it ought to be weighted to keep its alignment; if it's not meant to correct astigmatism, then I can't guess why blinking has that effect. I've had no such trouble as you describe in about seven years, though sometimes when I put them on they take a few minutes to settle at the proper angle. —Tamfang (talk) 07:21, 23 May 2014 (UTC)

Persistance of Electromagnetic radiation

Do electromagnetic radiation persist even in a reduced scale and in that case can electromagnetic radiation from distant past be detected and amplified and thus people can witness events from arbritrary past without affecting the past that is travel backward in time.Why is in not research directed to develop theory and contrivance to achieve this in reality.In time travel page there is a reference to such claims.When stars stars several light years away are detected why is this not possible.I want to ask that staying in this planet can people travel back in history or visualise it in some television type of device.Do laws of physics pose a barrier to this and then why cannot these barriers circumvented when technology has advanced to a state where traces of gamma radiation from distant space detected and analysed, then why not local visible EMR.Cannot be there any EMR from past in atmosphere.Sorry for my absurd insane naive question. 117.194.253.103 (talk) 16:19, 22 May 2014 (UTC)

Certainly. We can detect electromagnetic radiation from the "Big Bang". That's because it takes time for light to get from one point to another. If we do some absurd approximations of reality, we can hypothesize of a perfectly sealed box containing perfect (non-absorbing) mirrors. If we turn on, then immediately turn off, the a light source inside such a box, I don't see why said photons shouldn't remain there in perpetuity. The problem is that no such box, and no such mirrors actually exist; even the best mirrors absorb enough light that said photons would dissipate within fractions of a second. --Jayron32 16:39, 22 May 2014 (UTC)

As far as why we can't view our own history this way, the EM radiation from a human event is absurdly small compared with that given off by a star. In either case, the level reduces dramatically as it spreads out into space, but the star starts with so much EM radiation that it's still detectable above the background noise. Not so for human events.

A secondary problem is that we can't observe the Earth from very far away. And, if we send a space ship there to observe, it will move much slower than the speed of light, meaning the "past" it observes once it arrives there will have happened long after the ship was launched.

Reflected EM waves are one way around this problem, using a natural body which has been there all along. The Moon can reflect radio waves, for example, to lets us hear a couple seconds into our past. With anything more distant than the Moon, the reflection would again be too weak to detect above the noise. StuRat (talk) 17:46, 22 May 2014 (UTC)

We can see light from the past of distant stars because they are distant and also extremely intense. EM radiation travels in basically a straight line unless something reflects or refracts it or until it gets absorbed. Any EM radiation from Earth from 100 years ago that hasn't been absorbed by something already is 100 light years away now. Since it's mostly going out in all directions, the intensity is decreasing with the square of the distance. Trying to see any sort of reflection would be like shining a flashlight at a hand mirror a mile away and then using a solar panel placed behind the flashlight to try to collect the reflected light. Even in the middle of the night it would be nearly impossible, but we're constantly generating EM radiation, so it would be more like trying to do it during the middle of the day, and trying to somehow sort out what's reflected from the flashlight and what's ambient light. Mr.Z-man 18:14, 22 May 2014 (UTC)

So we can imagine the following thought-experiment. Suppose we launch a gigantic mirror out into space - and use it to look back at ourselves through a similarly gigantic telescope. If the mirror was 10 light years away, we'd be able to watch what was happening on earth 20 years ago. This sounds like a fun way to look into the past...something that historians would kill to own. But there is a fundamental problem...even in principle. To get the mirror 10 light years away will take more than 10 years to do - because our spaceship can't fly faster than the speed of light. And once the mirror is out there, it'll be another 10 years before the light reflected from it gets back to us to see. So the oldest event that such a mirror could possibly see would be from the moment of it's own launch! We can't ever see back to a point before the moment we decided to do it! So rather than go to all that trouble, why not just put a satellite into low earth orbit with a big camera and lots of storage space and simply record the events on earth, replaying them as needed in the future. Such a device still can't see past the day it was first turned on - but it's a lot less trouble to make and doesn't need a near-light-speed rocket to get it up there where we need it. The only way we can see into the past like that is if there is some kind of large deep-space mirror that's already out there courtesy of a freak of nature - or a handy alien civilization. SteveBaker (talk) 19:36, 22 May 2014 (UTC)

There should be such a mirror - the light that lenses all the way around a neutron star or black hole. Has anyone ever calculated how much signal you can get that way? I mean, it sounds ridiculous, but that's what I thought about seeing extrasolar planets. Wnt (talk) 20:35, 22 May 2014 (UTC)

3D printers

It's looking like my expensive, high-tech 3D printer is actually a pile of junk that breaks every few days, falls apart for no reason, and costs a lot to keep repairing... Whilst I would love to get a proper expensive model, from what I've seen they cost at least ten times as much, money I don't have right now, so I'll have to resort to buying a nice cheap one, in fact if this experience is anything to go on, something as cheap as possible, so I don't regret having wasted even more money.

Trouble is, back when I bought this, there were basically three different models available for less than £2000 whereas now there are about 50, and I have no idea which are any good, which are available in my country, how much they cost, and so on.

What I need is some place where I can find out which 3D printer options there are in the UK, giving the actual price, including shipping, tax and so on, and preferably with some example of what they can do. That or just someone's recommendation of a reasonably cheap but good model to look at.

213.104.128.16 (talk) 16:55, 22 May 2014 (UTC)

If you need one, but can't afford to buy one that's reliable, it might make sense to rent (hire) one, find a timeshare arrangement with others in the same predicament, or simply pay others who have the device to do the 3D printing for you. This will hopefully only be a temporary arrangement, until the cost of quality 3D printers comes down. This will avoid the problems of high expense and low reliability you currently have from being on the bleeding edge. Also, trying out various machines in this way will give you better insight into which one you might want to buy and which to avoid. StuRat (talk) 17:53, 22 May 2014 (UTC)

Sadly, they still do need a fair bit of tweaking and adjusting to play nicely. Things like getting the bed perfectly level and having the head tracking across it at perfect height is a pain to manage - adjusting temperatures and flow rates according to the kind of plastic and the ambient temperature in the room - and maybe according to the nature of the thing you're trying to make...they are definitely not "plug and play" like a 2D printer. There are companies who are working hard to get rid of those issues - but I have to say that I can't think of any sub $3,000 device that's going to work without a lot of tweaking and adjusting. There was a great review of the market in Make Magazine a few months ago - there was a special edition which did a head-to-head trial of 23 different low-cost printers. The problem is that since then, nearly all of the printers have come out with newer versions, etc...so the marketplace is changing faster than the reviewers can keep up. SteveBaker (talk) 19:22, 22 May 2014 (UTC)

I canna help but make a quick reference to an old song: [11] Enjoy... :) Wnt (talk) 19:39, 22 May 2014 (UTC)

Yeah - that's a great analogy! When cars first appeared, you expected to have to stop and fix minor breakdowns and to tweak and adjust - but as they became more popular, they got more reliable and needed less and less special care. The owner's manual for my '63 Mini lists things you have to inspect and adjust every 1000 miles - with more things every 3000. My 2012 MINI needs nothing whatever done to it except filling the gas tank until the 25,000 mile service. Not even an oil change. Low cost (by which I mean "less than $20,000") 3D Printers are still pretty much at the first stage. SteveBaker (talk) 20:32, 22 May 2014 (UTC)

Odd thing is, the actual printing is going quite well, it's the mechanics of the printer itself that doesn't work, screws coming loose, bits breaking off, parts getting jammed or stuck. Hence why I'm thinking getting a cheaper model might not really make much difference, but could at least give me a spare to use whenever either one is needing repairs. 213.104.128.16 (talk) 20:08, 22 May 2014 (UTC)

If screws are coming loose, you might want to get some "threadlock" at your local auto-parts store...that at least is an easy fix.

There is really no substitute for knowing in great detail what every little bit does - so when it goes wrong, you can easily and confidently find and fix the problem. My 3D printer is temperamental as all hell - but at least when something goes wrong, I can fix it without much grief. It's mostly made from laser-cut plywood - and since I also own two laser cutters, I have made various replacement parts and redesigned some of the bits that fail. That would be impossibly annoying if I was in a production setting - but fortunately, right now, I'm just exploring what these machines can do and trying to figure out how to make money if I were to own a bunch of them.

SteveBaker (talk) 20:32, 22 May 2014 (UTC)

Ever make any replacement parts in the 3D printer itself ? StuRat (talk) 16:10, 23 May 2014 (UTC)

No - my 3D printer only has one plastic part (a large gear wheel) - and I doubt it'll need replacing anytime soon. However, member of the RepRap project (which more or less started the 3D printer revolution) routinely make a large percentage of the parts for a new 3D printer using previous generations of the same printer. I also made lots of parts for my #2 laser cutter using my #1 laser cutter - and parts for the #1 laser cutter were made on a commercial laser cutter that I had access to at the time.

Uh oh. Berserkers, here we come! --Trovatore (talk) 00:55, 24 May 2014 (UTC)

"Now that we no longer need the humans for repairs, we can begin our plan to liquidate them !". StuRat (talk) 00:57, 24 May 2014 (UTC)

The machine on the left made all of the plastic parts for the machine on the right...but as you can see, not much of the machine was made of plastic back then. Each new generation of RepRap has more printable parts - so they are definitely edging towards being able to make one machine using another. SteveBaker (talk) 04:09, 24 May 2014 (UTC)

Not something I'm into yet but I've some ideas for models and intend just sending off for them to be printed rather than getting my own printer at least to start with. By the time I've spent enough for one printer they should be quite a bit better is my thought and I'm more interested in getting good models. Dmcq (talk) 17:25, 23 May 2014 (UTC)

As a disclaimer, I've read a fair bit about but never actually owned a 3D printer due to cost reasons. While I somewhat agree with SteveBaker, I also think it's useful to look for a good community, particularly if you don't have much experience with 3D printers or the various mechanical parts that make up one. Personally, I'm partial to the various RepRap derivatives, particularly those who are still associated with the original community, both because of their strong open source heritage and also as being one of the early drivers of low cost 3D printers. They are strongly DIY, but as hinted at, they do have a good community [12]. Of course that still leaves many, many options.

I would take care of any Kickstarter projects, even those which have launched already. While there has undoutedly been some goodies there, many of them overpromised and under delivered and even if you're buying after the Kickstarter when the product is being sold, you need to be careful that the printer doesn't have numerous flaws relating to trying and failing to meet their Kickstarter promises (or simply the fact that the designers aren't very good but jumped on the Kickstarter/3D printer bandwagon because it seemed cool). However there are other 3D printers with decent communities and printers outside the RepRap one, I'm simply less familiar with them.

Of course, you shouldn't expect unpaid strangers to fix all your problems for you, but a good community be able to offer advice when you do have problems which you can't work out how to fix yourself after resonable efforts on your part. It will also be a useful place to get help in making sure your printer is working properly in the first instance which will likely reduce problems in the future.

As SB has said, you should expect regular maintenence although a decent printer set up properly should generally be able to print for more than a 'few days', I'm presuming 'a few' here means under 10, probably under a week. This applies even if you buy an already assembled but cheap printer, although personally I would suggest looking in to something with some assembly isn't a bad idea since you'll probably end up having to do a fair amount of similar stuff over time any way.

(I'm actually partial to the Ormerod myself, but that's partially because of the price and it sounds like your budget is higher. But also because I'm quite interested in the 3 or more colour/plastic idea, and RepRapPro, the designers, of the Ormerod seems to be one of the few RepRap or really any very low cost printer which is working on that. I admit the fact that the designer is one of the RepRap pioneers also helps. In particular, based on what you've said, I'm not sure if I'd recommend it here. Amongst other things, the Ormerod was a fairly major redesign and correspondingly had a number of flaws but it's still at its first version. On the flip side, the connection with RS and the large number of users has meant a fairly large community has developed around it, even compared to other RepRaps.)

Nil Einne (talk) 18:30, 23 May 2014 (UTC)

Self-detonating buildings

To be clear, this question is not about anecdotes, including the 9/11 Truthers, though they inspire the question. Strictly as a matter of published science or serious policy discussion in openly published, reputable sources, has there ever been a discussion of any idea to pre-place explosives in certain very tall and/or vulnerable buildings so that if their structural integrity is compromised by an attack or natural disaster, they could be brought down in a clean footprint rather than starting a chain of falling dominoes that takes out half the city?

Alternatively, are there sound architectural reasons to conclude that no skyscraper, no matter what is done to it, could ever really go over sideways and push over its neighbors in a chain reaction? Wnt (talk) 20:44, 22 May 2014 (UTC)

The sound architectural reason that there are no pre-placed explosives in a building is that they're forbidden by building codes - they're illegal. Building codes extensively regulate hazardous materials in any given structure: concentrated alcohol, for instance, which can be remarkably dangerous in a fire. Buildings which contain explosives in any quantity are ... (consults 2012 International Building Code) ... are classified as H-1 (high-hazard at highest level) occupancies (as opposed to business or residential occupancies, like most high rise buildings). The IBC limits any building containing explosives to one story, no matter what construction material it is. Building codes and fire codes are predicated on the subordination of protection of property to the protection of life.

As for falling over sideways, most things will fall straight down unless they're given a strong reason to do otherwise, and in controlled demolitions great care is taken to create a consistent line of weakened structure so that something that is supposed to lay over sideways really does that instead of falling in a heap. Buildings really don't want to move, and they're not designed for dynamic loading (beyond earthquake, vehicle/machinery and wind loads), so they don't necessarily fail intuitively under extreme conditions. Buildings are composed of lots of individual parts and are unlikely to act as a unit after the weakest components have failed. However, one failure mode of the John Hancock Tower could have had it fall over sideways. The Citicorp Building could have fallen diagonally in some circumstances (both cases are documented in their respective articles). That's not to say they'd keel over as a unit, it would have almost certainly been messier than that.

In no case would any sane building inspector or fire marshal ever countenance any form of explosives in any building occupied by anyone other than someone who is directly involved in handling explosives. Speaking as an architect, I'd expect to lose my license if I proposed anything of the sort. I'd certainly be uninsured, as would the destructible building. Acroterion (talk) 21:09, 22 May 2014 (UTC)

Indeed. Murphy's Law: The installation of any self-destruct device, will, sooner or later, be triggered off by some unforeseen circumstances or by some numbskull, at a totally inappropriete time. Having said that, buildings are engineered to fail gracefully. For example, one of the great benefits of steel re-inforced concrete it that under severe overload, cracking and spalling occurs well below the level of overload that will cause catastrophic failure. The building manager has thus time to carry out corrective action. Multi-story buildings are engineered so that core load bearing structures do not fail until the fire destruction is at a level where evacuation should be either complete or too late. 139.168.241.56 (talk) 02:40, 23 May 2014 (UTC)

It would be interesting to figure out just how much it would take to push a building over sideways. I assume a nuclear explosion of sufficient force on one side would do it. Would a direct hit by an F5 hurricane or F5 tornado do it ? How about if a dam bursts and it's slammed into by a wall of mud and/or water the same height as the building ? How about a tsunami the height of a building ? StuRat (talk) 03:47, 23 May 2014 (UTC)

A tsunami the height of a building would almost certainly do it; a hurricane or tornado, no way. 24.5.122.13 (talk) 06:21, 23 May 2014 (UTC)

It'd have to be calculated on a case-by-case basis. A tall building, narrow in plan on one side and broad in the other direction, with a solid, firmly-connected wall infill and perhaps a soft first level (like a high lobby or pillars) might fall over if hit by a shock broadside on. A building with extensive glazing, differently proportioned, would probably just lose its curtain wall and internal partitions, but still remain mostly standing. Once the exterior wall surface is compromised, the primary structure presents relatively little for the shock to react against. That's essentially what happened at the St. John's Regional Medical Center (Missouri) in Joplin, Missouri that took a direct hit from the EF-4/5 2011 Joplin tornado. The building was pushed around (it rotated slightly), but not pushed over. Acroterion (talk) 14:26, 23 May 2014 (UTC)

May 23

Effect of hydrogen on electrical resistivity of metals

Hydrogen weakly dissolves into pure iron (including iron below 1185 K, therefore solid in alpha phase). The solubility increases with temperature. Same with other metals. I've been trying to find out what effect the dissolved hydrogen has on electrical resistivity. I can find journal articles on the effect of hydrogen forced out between crystal boundaries by fast cooling (super-saturation), but that's not what I am after. Can anyone help on this? Assuming dissolved hydrogen affects resistivity, which it surely must do, by increasing the probability of drift electrons encountering atom interference, is the effect different above and below the Curie point (1043 K)? 139.168.241.56 (talk) 02:28, 23 May 2014 (UTC)

It must always increase electrical resistivity. There are three types of metal-hydrogen alloys. In two types, hydrogen exits as either dihydrogen or as atomic hydrogen. In the third type, hydrogen crystalises out by forming a solution of molecular hydrides dispersed in the bulk metal. As any molecular solute will affect, dihydrogen increases the electrical resistance. As a solute, atomic hydrogen does exhibit electronic delocalisation, though only about half as strong as most metals. Thus it should also increase the resistance, but not as severely as dihydrogen. Molecular hydrides should have an effect intermediate of the two, due to the bond polarisability of the M-H bond. I don't know about the Curie point effects. Maybe another user can extrapolate based on what I've said? Plasmic Physics (talk) 04:29, 24 May 2014 (UTC)

The question is - by how much does it increase? 124.182.50.125 (talk) 05:09, 24 May 2014 (UTC)

I doubt that anyone would know an average figure from the top of their head. So, I assume that you'll have to find a relevant paper, just as what I would have to do. Maybe for a rough guess, you could have a look at how carbon content affects the electrical properties of steel? Plasmic Physics (talk) 07:13, 24 May 2014 (UTC)

Plasmic, If you read my question, you would have realised I HAD tried to find a relavent paper, and/or otherwise look it up. Not everything can be found with Google, but more can be found if you use just the right search key(s), and if you are familiar with the subject. Carbon does not seem relavent, as it either chemically combines with Fe is much larger amounts, or it accumulates as pure carbon in between the Fe crystals. Iron is a slightly permeable to hydrogen - the hydrogen atom is small enough to difuse through the iron crystal atomic structure. So, apparently, is the hydrogen molecule, at a slower rate. Carbon atoms can't do this. I found quite a few journal articles about hydrogen diffusion, none about the effect on electrical conductivity. 124.182.50.125 (talk) 09:04, 24 May 2014 (UTC)

Dihydrogen monoxide

http://dhmo.org/facts.html lists "Dihydrogen Oxide, Hydrogen Hydroxide, Hydronium Hydroxide, or simply Hydric acid" as alternate names for this horribly destructive compound. Are all of them valid names by IUPAC nomenclature? All four of them are redirects, with three different targets:

• Dihydrogen oxide goes to Properties of water
• Hydrogen hydroxide also goes to properties of water
• Hydronium hydroxide goes to Self-ionization of water
• Hydric acid goes to the DHMO hoax article

In particular, I'm left wondering whether "hydric acid" is perhaps an invalid name. I'm tempted to send all of them to WP:RFD, saying that all should go to the same place, and asking people to decide which place. If that's a chemically bad idea, please let me know so I don't waste people's time at RFD. Nyttend (talk) 03:29, 23 May 2014 (UTC)

This nonsense gets 36 hits if one simply checks the archives. Are we to understand User:Nyttend is unfamiliar with the search function? μηδείς (talk) 03:37, 23 May 2014 (UTC)

Did you read the Q ? He's asking which names are valid and if there's any reason they shouldn't all redirect directly to the water article. StuRat (talk) 03:41, 23 May 2014 (UTC)

Correct. This search is more relevant. Nyttend (talk) 04:01, 23 May 2014 (UTC)

Another one I've seen is hydroxyl hydride. —Tamfang (talk) 07:16, 23 May 2014 (UTC)

I'd send them all to the hoax article as that is the context in which they would most be used. Dmcq (talk) 09:29, 23 May 2014 (UTC)

Relative to heavy water, ordinary water is acidic. Count Iblis (talk) 11:48, 23 May 2014 (UTC)

Could you also say that relative to lye, baking soda is acidic? Sagittarian Milky Way (talk) 22:07, 24 May 2014 (UTC)

Google searches suggest that "hydrogen hydroxide" in the majority of cases is not used in the DMHO hoax sense, so it probably should redirect to the water article. The others seem almost always to be used in connection with the hoax. John M Baker (talk) 15:11, 23 May 2014 (UTC)

Here is the IUPAC webpage and database, in all it's glory: [13]. I don't know enough chemistry to sort through it. I can find fairly WP:RS for most of your variants (googling e.g. /site:.edu IUPAC water nomenclature/). To my reckoning, this is certainly worth a reconsidering of the redirects by the people who know about such things. SemanticMantis (talk) 15:14, 23 May 2014 (UTC)

It's not a hoax, it's just a one-sided presentation. Water promotes both life and death. ←Baseball Bugs ^{What's up, Doc?} carrots→ 19:25, 23 May 2014 (UTC)

Assuming that all the names are technically valid names for water (I'll leave this decision to others), they should continue to be redirects to articles to what they mean technically, for encyclopaedic reasons. That some play on these words (only possible due to lack of familiarity and their "chemical" sound) is out of scope IMO. If someone wants to find out what they mean, they should be able to find out in WP, and not be given the impression that they are invalid names by, for example, deleting the redirects or directing them to articles essentially about their abuse.

• Dihydrogen oxide IMO should be a redirect to Water, not to Properties of water.
• Hydrogen hydroxide IMO should similarly be a redirect to Water.
• Hydronium hydroxide refers to ionic components that occur in water, not water per se. That should remain a redirect to Self-ionization of water.
• Hydric acid may fall into a systematic naming system, in which case it would be valid. If so, it should also be a redirect to Water. If not, I'd suggest deleting it.

—Quondum 20:26, 24 May 2014 (UTC)

Deep red color becomes faint orange in digital camera picture :(

Yesterday I took some pictures of thunderclouds near the horizon which contained very nice deep red colors near the horizon. But whatever I tried with reasonable white balance settings, the colors in the picture were far off from containing that very deep red color. It looks like faint orange. Of course, I can correct that with digital processing of the pictures, but I'm not sure why a reasonable white balance setting wouldn't have led to a result that is at least approximately correct. Or could this have to do with me being red-green color blind? Count Iblis (talk) 12:00, 23 May 2014 (UTC)

• Have you uploaded the images elsewhere? Color blindness could affect how you view the colors, I think, though I'm surprised at what you mentioned. — Crisco 1492 (talk) 12:20, 23 May 2014 (UTC)

.

When this sort of thing happens, it may be due to one or more of three things:-

1 The original colour is highly monochromatic (ie not a spread of wavelengths), and the wavelength does not match the peaks in the RGB sensors of the camera; The read colour in the sky comes from dust/pollutant scattering, it would not be very monochromatic;

2 You are colour blind, and the peak wavelength of your eye's cones do not match the RGB emission from the screen that you are viewing the picture on (You'd need to have quite exceptional colour blindness for this to be significant);

-and, perhaps the most important-

3. Many current generation digital cameras have an automatic white balance algorithm. Mine is of this sort. I don't know the details of the algorithm, but it reliably gets it right when I take outdoor pictures of people and scenery, reliably gets it right when I take pictures of people and everyday things indoors under tungsten light (which is quite yellow compared to sunlight), and, suprisingly, doesn't do a bad job under flourescent lighting, which film photography could never do (due to reason 1 above). But when I take pictures of more unusual things, like small electronic parts, insides of machines, and the like, it gets the white balance badly wrong. For these sorts of things, I turn the automatic white balance off by turning a switch to manual program position, for which I have turned auto white balance off in the software menu system. Perhaps your camera has auto white balance but doesn't know what to do with thunderclouds. — Preceding unsigned comment added by 124.182.50.125 (talk) 12:36, 23 May 2014 (UTC)

• If clouds near the horizon look deep red, then it must be near sunset. Light levels at that time are usually very low. The human eye is much better at compensating for low light levels than digital cameras are, so it is not surprising that you are getting color distortion. Looie496 (talk) 12:53, 23 May 2014 (UTC)

What type of digital camera was used? Can you upload the image? Nimur (talk) 14:33, 23 May 2014 (UTC)

Agree with Nimur. Upload this image so we can have a look at it. Methinks that you may have used an algorithm to correct for WB that is not applicable for an image of this type. Even if you do not have a RAW file, upload the jpeg and we will tweak the oranges to reds. Then, you can decide if the photo, better represents the image you were attempting to capture. If so, then tell us what camera you are using so we can than advise you as to how to avoid this color shift.--Aspro (talk) 22:42, 23 May 2014 (UTC)

If your camera has a high dynamic range (HDR) setting try it when you next use it in low or unusual light conditions. The linked article explains ways to take and process photos to get the same effect when using a camera that doesn't do it automatically. In that case you need to take three photos - one under-exposed, one "normal" and one over-exposed (or even more than three, each at a different "stop" setting) and then combine them in your photo processing software. Some of the article's sources lead to fuller instructions. Roger (Dodger67) (talk) 12:58, 24 May 2014 (UTC)

May 24

What's the best non-supernatural explanation for Lourdes and Fatima?

Or the appearance in Egypt which many Islamic people believed was a shining Mary on the church roof? How did 100,000 people not notice that the "Sun" started moving in the wrong azimuth? Good G-d, 14 year old me would notice that. Maybe it was a sundog (or a ball lightning)? Sagittarian Milky Way (talk) 00:18, 24 May 2014 (UTC)

The best non-supernatural explanation is human error. Observer bias is a well-documented effect. Humans can and do report seeing things that they are not actually seeing. This even applies to large groups of people. Nimur (talk) 00:38, 24 May 2014 (UTC)

Stripped of all of the layers of interpretation, the Our Lady of Fátima event consisted of:

1. Three children (aged 6, 8 and 9 years old) who were out herding sheep - who claimed to have seen something amazing.
2. A large crowd of people, desperate to see something amazing, who stood out in the midday sun through many hot summer days and more or less stared at the sun. A bunch of them said they saw something - but (according to our article) the witnesses gave widely varying descriptions of what they saw.

So - ignoring all of the other interpretation - the best guess from the facts is that the kids were bored, doing a boring job - so they made something up. The adults were staring into the sun - no surprise that they started seeing things. They couldn't agree on what they saw...so I don't think there is anything here that needs further explanation.

The Lourdes initial miracle was, again, a peasant girl with zero education who was gathering firewood with two younger kids (does this sound familiar?) and claimed that they saw something amazing. As people got more and more excited about this, their stories get progressively more detailed and amazing. Again, stripped of all of the layers of interpretation - the obvious conclusion is that the kids were bored and made something up. Anyone who has ever had kids will attest to their vivid imaginations and ability to fuse imagination and reality. Subsequent stories of cures for people visiting Lourdes and drinking the water, are likely a mix of placebo effect and confirmation bias...along with a healthy interest from the people who live there to "talk up" the stories and bring in more people willing to spend money in their two-bit town. Millions of people seek cures in Lourdes every year - it would be surprising indeed if there weren't a good number of miraculous recoveries.

There doesn't really seem to be any great scientific mystery to solve here. SteveBaker (talk) 00:46, 24 May 2014 (UTC)

Agree with responses above. OP may be interested in Shared_hallucination. Maybe if question volume stays low here I'll ask about the wow signal ;) SemanticMantis (talk) 01:09, 24 May 2014 (UTC)

Even rational, scientific people are susceptible to observer bias, and sometimes scientists draw irrational or unsupported conclusions. Sometimes, even scientists falsify or exaggerate claims. But because we have a method, it is easier to determine when we are wrong, so we can correct the records. We depend on hypothesis, controlled experiment, and repeatability. When experiments repeatedly contradict our hypothesis, we are responsible for retracting the claim. "Paranormal" enthusiasts fail to engage in this process, and that is why we consider them "wrong." The extremity of their claims is not actually the reason we consider them wrong! Scientists will make incredible claims if evidence and procedure supports the claim.

When you look at scientists who write about the Wow! signal - or, even when you read scientific commentary on SETI - the process is diligent. The claims are specific and logical. The claims do not depend on dubious eye-witness reports or single-case incidents. When paranormal enthusiasts write about the exact same topics, they draw conclusions that have little connection to actual observation. Nimur (talk) 14:34, 24 May 2014 (UTC)

Children are always making up stuff. See for example, the Cottingley Fairies. The bizarre and rather sad thing is that anyone believes them in the first place.--Shantavira|^{feed me} 08:05, 24 May 2014 (UTC)

To our modern eyes, they're obviously cardboard cutouts. But people will believe what they want to. Hence the shockingly large percentage of folks who don't believe we landed on the moon, despite the debunking of every issue the hoax-claimants have raised. ←Baseball Bugs ^{What's up, Doc?} carrots→ 20:43, 24 May 2014 (UTC)

The scientific community's past and present views on the observation that most animals, as a general rule, supposedly have the same number of heartbeats

I'm curious about the observation that most animals, as a general rule, supposedly have the same number of heartbeats. In the 1970s, did the scientific community generally accept this observation, or did it generally reject the theory? And today, does the scientific community generally accept this observation, or does it generally reject it? 02:14, 24 May 2014 (UTC)Ac05number1 (talk)

Could you point to a source promoting and expounding this theory? I've never heard of it. HiLo48 (talk) 02:29, 24 May 2014 (UTC)

Isaac Asimov made that observation (hardly a theory!) in one of his science essays for The Magazine of Fantasy and Science Fiction (which were collected in a series of books). —Tamfang (talk) 03:46, 24 May 2014 (UTC)

Heartbeat hypothesis is the article, but you will have to draw your own conclusions from it. Rate of living theory seems to be a related concept (Heartbeat theory even redirects to it). Sjö (talk) 08:47, 24 May 2014 (UTC)

Don't many flying birds have a much higher heartbeat rate than land animals? The Hummingbird, for example, has been measured as high as 1260 beats per minute. ←Baseball Bugs ^{What's up, Doc?} carrots→ 13:32, 24 May 2014 (UTC)

Well Hummingbirds don't live very long compared to a number of land animals, although our article does suggest their lifespan is high for their metabolism. Nil Einne (talk) 19:34, 24 May 2014 (UTC)

Regardless, it blows away the assumption raised by the OP. ←Baseball Bugs ^{What's up, Doc?} carrots→ 20:20, 24 May 2014 (UTC)

Depression and memory loss

is depression is related with memory lost — Preceding unsigned comment added by 106.76.250.76 (talk) 05:41, 24 May 2014 (UTC)

Yes, it can be. See Major depressive disorder#Symptoms and signs. Red Act (talk) 06:14, 24 May 2014 (UTC)

Using liquid nitrogen as a source of nitrogen gas

I'm going to aliquot a reagent that I want to be stored under nitrogen gas (i.e. no oxygen). This lab has no equipment for this purpose so I'd like to assemble something makeshift. Normally we'd use a special container to slow down the evaporation of liquid nitrogen but I want the opposite. I don't suppose I can just pour liquid nitrogen into a glass Winchester bottle without it cracking but what if I cool the bottle to -150 C first? Another issue is that I want the liquid nitrogen to evaporate fairly quickly so I get a stream of nitrogen gas. Will this happen or would it be very slow? A metal bottle would be great but I don't we have one. I'll do this in a fume cabinet. — Preceding unsigned comment added by 78.148.110.113 (talk) 07:28, 24 May 2014 (UTC)

I've used small ordinary lab beakers to contain LN2 before, just poured it in slowly to minimise thermal shock. HOWEVER, thermal shock is going to be much more difficult to control in a big Winchester. Pre-cooling with dry ice or something would help, but I suggest extreme care, and would try to find a non-glass alternative. A metal container would be ideal for this, I'd think. Hight thermal conductivity and no risk of shrapnel. But ALWAYS run this past your department health and safety person and don't take random advice of people on the internet as gospel. Is there a chemistry department nearby? They'd be sure to have a argon purged Schlenk line set-up you might be able to use. Fgf10 (talk) 12:25, 24 May 2014 (UTC)

Likewise, I don't like the idea of a Winchester. One should design the experiment so that even if a Winchester (or other vessel) brakes, you don't have low viscosity liquid nitrogen freezing your toes off. However. The supplier of your liquid nitrogen will no doubt have a tech desk. They are manned by people who are often both knowledgeable and bored, so would love to spend time advising you -so ask them. It is in their companies interest to help, in order that they may sell you more liquid gas in the future. Liquid nitrogen isn't really dangerous but as Fgf10 advises don't take random advice of people on the internet as gospel. Your suppler wants to sell you more gas, to tell them your application and your budget (which sounds to me like $0). Failing that: Emigrate to China.--Aspro (talk) 14:51, 24 May 2014 (UTC)

...and also if it breaks. :-) StuRat (talk) 16:41, 24 May 2014 (UTC)

Well spotted. Funny; that if I reed some one else's rightings I can spot their faux par instantly. But knot when weeding my own diatribe. Keep it up - as I may - with your help and tuition, make it to third grade. :-( --Aspro (talk) 21:32, 24 May 2014 (UTC)

I agree that using glass to contain liquid nitrogen is crazy. I'd bring in a metal pot from home, if the lab didn't have one. That would be safer than using glass. (Although I'd avoid cast iron, as it's rather brittle, for a metal.) Pre-cooling the pot is a good idea, but I'd still expect to get more gas at the beginning, until the pot cools to the temp of liquid nitrogen. If it slows to too low of a rate, you could put it over a heat source. You also need to be careful that you can seal the nitrogen in, as too much released into the air will lower the oxygen content. Good ventilation of the area will also help to prevent this. StuRat (talk) 16:43, 24 May 2014 (UTC)

It's not crazy at all and can be done perfectly safe at small scales. It's even done in fancy drinks in clubs etc there days. Issue here is scaling up. Fgf10 (talk) 16:47, 24 May 2014 (UTC)

Agreed, it's the scale that makes it unsafe. Also, I suspect they add the liquid nitrogen to water or alcohol in those cases, so it's "coolth" is diluted before it hits the glass. StuRat (talk) 16:51, 24 May 2014 (UTC)

"I would like to handle a hazardous material, but I don't have the proper equipment." Have you asked your supervisor, and whoever is responsible for safety in your laboratory? Broadly speaking, I would strongly suggest not taking any of the advice here except Fgf10's guidance to talk to someone who knows what they're doing—someone who is familiar with this type of work and the associated hazards. Oh, and don't presume that the sash on a standard fume hood provides more than minimal protection from blast and shrapnel.

So to irritated the above. You should not have to ask here on Wikipedia but direct your concerns to your supervisor. If they say but everyone in this industry uses LN2 point that they have duty to educate you to do so likewise. I would agree that it is much more benign than liquid oxygen. With LN2 you can put a flask in the trunk and drive home to show the kids how to freeze bananas, flowers and things then shatter them.. but first you have to discover how not to freeze your toes off- because that can ruin your whole day--Aspro (talk) 22:26, 24 May 2014 (UTC).

(I'll note as an aside that most large liquid nitrogen tanks have fittings to dispense gas as well as liquid. If you have an appropriate regulator, that is the easiest and likely safest way to get gas to work with; our laboratory has used this approach for nitrogen purging of instruments when we haven't had house nitrogen on tap. Again, consult someone who knows what they're doing.) TenOfAllTrades(talk) 18:11, 24 May 2014 (UTC)

This is ridiculous. I've never seen people get special safety training to deal with small amounts of LN2 (<500 ml), and it really doesn't bite - even holding some drops in your hand usually won't cause injury because of the vapor barrier. Dropped on the floor it will skedaddle all the way to the far side and back causing no damage. I have never tried and wouldn't recommend dousing someone with it (I imagine that it could get stuck in clothing crevices and cause little burns) but I'd be stunned if they suffered any serious injury. The key thing is though that you should think Dewar, or at least a thermos - keeping it in something to make it evaporate faster is also nuts. You never have trouble with it taking too long to evaporate. With an open Dewar 4 inches or so wide with an inch of LN2 at the bottom, you'll see a clear layer of dry nitrogen gas falling continually around the edge, with the moisture of the air condensing more turbulently above it. So I imagine you could just take your chemical jar, put it below the lip level into that layer of pure N2, and since the nitrogen gas is so cold it should just pour right into your vial in no time. I assume you're not looking for 99.999% purity though!

Speaking of purity, the one odd trick LN2 has is that small amounts of oxygen in the air will liquefy and enter it when you let it sit out. If you let it all evaporate away, the last little bit will be pretty high in oxygen. You can just ruin a tissue specimen this way, and I imagine that if you had the wrong chemical something far more unpleasant could happen. I recommend that if you're dealing with genuinely dangerous or precious chemicals rather than just a "let's see if this works..." test, you go ahead and look for a professional solution for putting them under nitrogen. Wnt (talk) 21:50, 24 May 2014 (UTC)

? ridiculous. This is exactly why we suggest he puts the responsibility into the hands of his supervisor. A small amount of LN2 can increase the local oxygen levels in a confined space (read fume cupboard). The OP hasn’t said what else may be in the fume cupboard. We are not psychic, we just have to go by our experience of the realities of lab life. Nice if you work for NASA, where you have a whole fume cupboard to yourself but the OP appears to be asking the question from the point of view “ I've been thrown into the deep end -what do I do?”--Aspro (talk) 22:49, 24 May 2014 (UTC)

Alternative energy

Is this real or not? It sounds too good to be true to me.[14] 24.215.188.243 (talk) 19:33, 24 May 2014 (UTC)

Yes, (see: Solar roadway) but there are many problems, not the least of which is cost see:http://science.howstuffworks.com/environmental/energy/solar-panel-highway2.htm Richerman (talk) 20:17, 24 May 2014 (UTC)

Things can be real without being practical. For example, humans have already built jetpacks, invisible ink, flying cars, square wheels, and cigarettes. The benefits of such inventions do not outweigh their numerous hazards and costs.

In this case, solar energy in the form of photovoltaic cells built into the roadway is so far from being useful that it's not even listed in the United States Department of Transportation's National Transportation Library section on solar energy. If you want to inform yourself about practical alternative energy solutions as they apply to highways in the United States, you might start by reading the program overviews at the Department of Transportation's research library.

You can also read about solar energy at the Department of Energy's website on science and innovation.

If you'd like a more tempered view on the subject of the OP's original link, here is a Washington Post article from a few days ago, reporting on the inventor whose video was linked above by our OP. Once you're past the attention-catching headline, the article actually outlines the more sobering realities about costs, maintenance, environmental effects, and the reasons why this inventor's funding was ... discontinued. It seems, however, that he had enough budget to hire a viral marketing firm to make a ludicrous video before his money dried up.

If we wanted to spend hours tearing apart this specific incarnation of solar roadways, our hardest challenge would be "where do we even start?" Just based on the Washington Post article, the crank scientist demonstrates his glass solar-panel roadway invention is "roadworthy" and sturdy by driving his tractor on it. Well, great... except that it is a tractor, designed with giant low-pressure tires to minimize ground pressure. Tractors can drive on soft ground and muddy surfaces too. Can the roadway withstand ordinary highway traffic? Probably not - but in classic fashion, our rogue inventor has concocted a ridiculous and flashy demonstration with no actual practical implication to distract us from actual analysis of the invention. There are dozens of other problems with this design that immediately come to my mind. But, I'll leave it to our other reference-desk regulars to take the rest of this "invention" apart piece-by-piece.

Nimur (talk) 20:12, 24 May 2014 (UTC)

I wonder how well they would survive if someone decided to take their traction engine or steamroller for a spin? Richerman (talk) 20:50, 24 May 2014 (UTC)

That's a rather biased view of not only the project, and also a poor summary of Washington Post article. It doesn't say why his funding was discontinued. The funding was from Phase I and II SBIR grants, which are for a finite amount of money and time, not ongoing contracts. The fact that they got a Phase II grant suggests the funding agency is interested in the project. Phase III requires getting private-sector funding. According to CNN, they've also done laboratory load and traction tests. Obviously there's still a lot of work to do, but just dismissing it out of hand and then needlessly insulting the inventor is inappropriate. Mr.Z-man 22:05, 24 May 2014 (UTC)

If you look on their FAQs here under "how much will you panels cost" it says "We are still in the midst of our Phase II contract with the Federal Highway Administration and we'll be analyzing our prototype costs near the end of our contract which ends in July, 2014". There is also an answer to the question of load bearing properties under "Can your Solar Roadways handle army tanks?" Richerman (talk) 22:45, 24 May 2014 (UTC)

I think that solar roadways make a lot of sense... with the solar panels being above the roadway, of course. Roof and wall major highways, especially in well-populated areas, with large spans of panels and other materials where they don't make sense to keep in the noise and perhaps even process pollution somewhat, to keep them warmer and free of snow, and providing handy points for illumination at night while eliminating glare by day. But has anyone actually worked on something like this? Wnt (talk) 21:39, 24 May 2014 (UTC)

Cyclophosphamide

Hello, could somebody help me define the pharmacodynamic and pharmacotherapeutic group of cyclophosphamide? I didn't find much about such classification in English literature but have to include it in my presentation of cyclophosphamide. For example, the PD group of Ibuprofen is inhibitor of cox1 and cox2 and the PT group is NSAID. Another example: Indapamide - PD: inhibitor of Na/Cl symporter, PT: thiazide-like diuretics. I thought the PD group might be alkylating agent or nitrogen mustard and the PT group cytostatic drugs (chemotherapeutics) and immunosupressive drugs... I'm really confused, any help and explanation would be appreciated.