Wikipedia:Reference desk/Archives/Science/2014 March 26

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March 26

Kessler Corporation? A background check.

we can't give legal advice, of which this is a classic case. μηδείς (talk) 03:05, 26 March 2014 (UTC)
The following discussion has been closed. Please do not modify it.
I recently got a patent and it has been published. Lo and behold a couple of weeks later I got a letter from the above firm offering their services (for a substantial fee) to help me to find manufacturers interested in implementing the invention. I have already set different plans in motion and this offer is not on my map but I am still curious. I want to keep various options open. I wonder if anybody heard about the company (positive or negative) and could shed any light. Thank you --AboutFace 22 (talk) 00:47, 26 March 2014 (UTC) You could check with BBB, they have a review: Accredited A+  —71.20.250.51 (talk) 01:06, 26 March 2014 (UTC) If you have a patent you should be seeking advice from a patent lawyer, not some random people on the internet. μηδείς (talk) 03:05, 26 March 2014 (UTC)

Closed per μηδείς (talk) 03:05, 26 March 2014 (UTC) as a request for legal advice.
μηδείς (talk) 03:05, 26 March 2014 (UTC)

What is your reason for treating the question as a request for legal advice? It's not a question whose answer requires knowledge of the law or application of legal principles. --173.49.81.186 (talk) 04:21, 26 March 2014 (UTC)

The BBB is a 501(c)(6) non-profit Accreditation organization. "Background checks" on companies is mostly what they do. In the US, that's the 1st place most people look to check the reputation of a (US) company.  —71.20.250.51 (talk) 05:05, 26 March 2014 (UTC)

I appreciate the comment by the poster who objected to defining my OP as a request for legal advice. It was far from what I had in mind. I want to see if anybody had experience dealing with this company on a practical level. The original issue (obtaining the patent) was perfectly scientific, so this is its extension. --AboutFace 22 (talk) 14:22, 26 March 2014 (UTC)

This is in no way a request for legal advice. It's a request for information about a business, which was prompted by that business contacting the asker in relation to a published patent (itself a legal document, but that's irrelevant). Even if the question was asking for an opinion on a firm of lawyers, it wouldn't be legal advice ("You don't need to talk to an X lawyer about this" - Possibly legal advice, "Y,Z & Q LLP are a terrible law firm, all of their letters were printed on rabid bobcats which made them extremely hard to read" - not legal advice). As it is, the question isn't even related to patent law, just a company offering to help commercialise an invention, and using patent publications to find clients. MChesterMC (talk) 16:47, 26 March 2014 (UTC)

This is a reference desk. Maybe the OP could specify some matter we can help with, like the company's contact numbers, any news they have been mentioned in in the last few years. WE cannot give our own opinions of the company itself (see the section on opinions at the top of this page) or offer original research WP:OR or comment on their reliability or busniess practicess, which my subject us to suit for defamation, or give advice on patents ourselves, since that is indeed legal advice. IP 71 has given a helpful comment. μηδείς (talk) 17:34, 26 March 2014 (UTC)

The OP didn't ask for opinion. (His request was certainly not umambiguously a request for opinion, and arguably not one.) Even if he did, the helpful response would be to tell others to refrain from offering opinion, not to hastily declare the question "closed". Posters of questions may not always phrase the question the best possible way at first; useful answers can nevertheless be provided, not necessarily to the original question as asked, but to the question that the OP should have asked instead. In this case, the OP was really asked for input to help to form an opinion about an entity. What other people may have "heard" need not be subjective opinions, they can be verifiable facts. They can take the form of honors and recognitions, rankings, metrics of past performance, records of criminal conviction/civil penalties etc. --173.49.81.186 (talk) 02:51, 27 March 2014 (UTC)

IP;DR. μηδείς (talk) 18:07, 27 March 2014 (UTC)

Again I appreciate all comments. I've been surprised by the reaction. No hard feelings though. Wikipedia is a great place and the issue actually kind of faded in the background for me now. --AboutFace 22 (talk) 14:32, 30 March 2014 (UTC)

Dowmo alloy electrical resistivity vs temperature

Does anybody know where I can find information on the resistivity versus temperature characteristics of "dowmo" alloy (tungsten & molybdenum 50:50)? I need it over the range 300 K to at least 1200 K, so Mitchell's formula is unlikely to be accuate. Worthing's formula might be. I found nothing via Google. I know it's about the same as pure tungsten at the high end of the range, so even a single measured value near 300 K would help a lot. 120.145.131.60 (talk) 03:14, 26 March 2014 (UTC)

Light bulb brightness in circuits

Hey everyone, I have two questions relating to physics and electricity. I think I did them right, but I just wanted to double check:

1. A resistor measuring 330Ω and 3.1V, and an LED measuring 190Ω and 1.8V, are placed in series, both with a current of 9.5mA. If another resistor is added in series to the circuit, would the brightness of the LED change? I said no, because if the current is the same throughout the entire circuit in series, there would be no difference if another resistor was added, only the voltage would change.
2. The first resistor and LED (from the above question) are placed in series again, but the two are in parallel to a third resistor. If the resistance of both resistors increases, what would happen to the brightness of the LED? Here I said that the brightness would change because while voltage is equal throughout, and resistance increases, current must decrease throughout the circuit and so the brightness decreases.

Was I right? Thanks everyone. 64.229.204.125 (talk) 03:18, 26 March 2014 (UTC)

The question is incompletely stated. The current and voltage are also determined by the rest of the circuit, so rearranging things can change both the total voltage and current. It is likely that the implicit assumption that you were intended to make (but this reflects badly on whoever set the question) is that the source of the current is a battery or power supply of negligible internal resistance (this should have been made explicit in the question). From the initial setup, this is a voltage of 3.1V + 1.8V = 4.9V. You were then presumably supposed to make inferences about the voltage vs. current characteristics of each component and how this would affect the current in the diode in each new configuration. This gives you different results in the first question. In the second question, while your final answer is correct, the voltage does not stay the same throughout due to the different voltage vs. current characteristics of a LED and a resistor. —Quondum 04:02, 26 March 2014 (UTC)

1. IF the current through the series circuit is constant then you are right that the LED brightness doesn't change. Two problems: a) it's rather unusual to power a circuit from a constant current supply. For example a battery gives a constant voltage and adding a series resistor would reduce brightness. b) Ohm's law applies to the resistor exactly so 3.1V across a 330 resistor causes a current of 9.394mA, not 9.5mA. (A LED has non-linear I-V characteristic so Ohm's law cannot apply to it.) I have provided links to articles in Simple Wikipedia that may be helpful. The same subjects are covered in higher detail in Wikipedia.
2. IF the supply is a constant voltage then the 3rd resistor across the supply has no effect on the current in the LED, and you are correct that the LED brightness decreases when its own series resistor is increased. 84.209.89.214 (talk) 01:14, 27 March 2014 (UTC)

Sorry, I should elaborate on a few details. 1) There are only 2 significant digits to work with, so 330Ω was rounded up. 2) the circuit was completed on a breadboard, with the current being direct, but plugged into a power outlet. 64.229.204.125 (talk) 01:55, 27 March 2014 (UTC)

The exact behaviour will depend on the characteristics of the power supply. Many lab DC power supplies are constant voltage (to 2 s.f.), but some LED power supplies attempt constant current. Dbfirs 13:28, 27 March 2014 (UTC)

A note regarding rounding of the resistor value: 330Ω is widely recognized as a preferred value in the standard E12 series. These are values that approximate an exponential series and have already been rounded to 2 significant figures. The picture shows a typical resistor whose color bands orange-orange-brown-gold identify its value as 330 ohms +/-5%. 84.209.89.214 (talk) 13:21, 28 March 2014 (UTC)

Military careers

Is the military a good career for people who find desk work stressful? As although military is stressful it's a different type of stress to that of desk work. 82.132.244.5 (talk) 14:11, 26 March 2014 (UTC)

Yes, there's very little chance of being blown up by a roadside bomb if you're merely working at a desk. You might also want to look for numbers on the quantity of combat troops vs. the quantity of support personnel, many of which have... desk jobs. ←Baseball Bugs ^{What's up, Doc?} carrots→ 14:21, 26 March 2014 (UTC)

Different people find different types of careers "stressful" based on their aptitude and personality. That is, while one person may be energized and well suited to something like being a police officer, another person would find it highly stressful and unpleasant. There's no universal set of values for this thing. If you are in the United States and are interested in a career in the U.S. military, it is often recommended that you take the Armed Services Vocational Aptitude Battery test, which is designed to find a recruit's strengths and weaknesses, hopefully to place them on a career track to which they are well suited. I see by the geolocation of your IP that you are in the UK, so perhaps the UK has a similar method of evaluating potential military recruits for jobs they are well suited for. You may want to into that. --Jayron32 16:45, 26 March 2014 (UTC)

What did Folding @ Home accomplish?

I participated in the Folding @ Home program for a few years with a couple PS3s and home computers. The promise was that it might cure diseases and discover new treatments. But did it? --209.203.125.162 (talk) 17:28, 26 March 2014 (UTC)

Have you read Folding@home? It lists several conditions (such as Alzheimer's and Huntington's) where the program has been useful. I don't believe the project is intended to find cures itself, but to provide information that other researchers can use. Rojomoke (talk) 17:51, 26 March 2014 (UTC)

I seem to recall a few instances where it produced homology models that were usable starting points for molecular replacement, but I don't really have any sources for that. Actually, here's a source, although this was actually using data from Foldit not from Folding@home: Nat Struct Mol Biol. Sep 18, 2011; 18(10): 1175–1177. For what it's worth, it still seems like traditional homology modeling has a much higher success rate. (+)H₃N-Protein\Chemist-CO₂(-) 18:28, 26 March 2014 (UTC)

Eating nitrocellulose

What would happen if you eat some nitrocellulose?

Is it poisoning, or would it be much like eating regular cellulose? 91.77.188.8 (talk) 17:43, 26 March 2014 (UTC)

I am assuming that you are asking what would happen to a typical adult human being when he eats nitrocellulose? 140.254.227.69 (talk) 17:57, 26 March 2014 (UTC)

According to the encyclopedia britannica, nitrocellulose is used in gunpowder and explosives. Hmmm... I don't think you want to ingest that, because that sounds like smoking a cigarette. A pack of toxins into your bloodstream. 140.254.227.69 (talk) 18:02, 26 March 2014 (UTC)

Being explosive doesn't automatically mean it's not edible. Nitroglycerin, for example, is ingested as a heart medication. See Nitroglycerin#Medical use. StuRat (talk) 00:55, 27 March 2014 (UTC)

It's still a drug. Drugs that are intended to be ingested into the body should be carefully considered (including receiving advice from a licensed physician), because the ordinary person is unlearned in medicine and chemistry. 164.107.189.137 (talk) 20:40, 28 March 2014 (UTC)

I'm not advising that anyone take it as a med, just noting that it is prescribed as such. StuRat (talk) 20:22, 29 March 2014 (UTC)

I must add that safeness of chemical compounds has nothing to do with the name. The name is just used to describe the chemical structure or components. In order to identify the safeness of a compound, you may want to look up Material safety data sheet. 140.254.227.69 (talk) 18:12, 26 March 2014 (UTC)

According to the Nitrocellulose Safety Data Sheet, there are several problems associated with even getting close to the substance, let alone ingesting it. Always handle unknown chemicals with care. Wear gloves and goggles and maybe a lab apron, though, in most cases, you probably don't need a lab apron. (I never used one, and gloves are usually appropriate in a biomedical lab that deals with biohazards and stuff.) 140.254.227.69 (talk) 18:26, 26 March 2014 (UTC)

Nitrocellulose paper is very commonly used in western blots as a substrate onto which to transfer protein from an SDS gel, and although it is (obviously) flammable if exposed to an ignition source, I don't think it's quite so super hazardous to handle as long as you don't set it on fire. To answer the OP's question though, no, you shouldn't eat it. FYI, that's the answer to virtually every question that starts with "Is this [random thing I found in lab] safe to eat..". The answer is always "no". (+)H₃N-Protein\Chemist-CO₂(-) 18:40, 26 March 2014 (UTC)

Indeed, "should I eat it?" should always be followed with the question "is it food?" If the latter is "no" a safe assumption is that the former should be "no" also. --Jayron32 23:13, 26 March 2014 (UTC)

Is it possible to return the pulse by CPR when having asystole in the heart?

Someone told me that the pulse can not return by CPR if the heart has total asystole. He told me that when the pulse return it says that the heart had only a few contractions before, and that is the reason why the pulse returned (about 10 for a minute). Is it right or not? 213.57.123.85 (talk) 18:48, 26 March 2014 (UTC)

CPR (but not defibrilation) is still indicated in case of asystole. Recovery, while unlikely, is still possible. Ruslik_Zero 19:20, 26 March 2014 (UTC)

I know that CPR (without defbriliation) is still indicated in case of the asystole. But it's definitely not the question... The question is What had been under the chest before you returned the pulse. Was it total asystole or was it a few contractions. I hope I explain myself well, because English is not my mother language. 213.57.123.85 (talk) 19:54, 26 March 2014 (UTC)

During a cardiac arrest, the aim is to defibrillate the patient to achieve a return of spontaneous circulation (ROSC). Asystole is a non-shockable heart rhythm (i.e. it is not to be defibrillated). If the patient is in asystole, CPR is performed to try and change the heart's rhythm into a shockable rhythm, so that the patient may then be defibrillated. (I am an advanced life support trained final year medical student.)

The masses and tensions of violin strings

I've been trying to find masses and tensions for a real life violin string, so that I can make realistic physics problems about the wave speed and frequencies. All I can find in web searches are physics problems posted to sites like answers.com. They give masses on the order of ~0.500 grams. Is that realistic? That tends to lead to tensions on the order of hundreds of Newtons. Are violin strings really under tensions that huge?Inkan1969 (talk) 19:27, 26 March 2014 (UTC)

Basic physics of the violin points us to this chart which gives tensions. -- Finlay McWalterჷTalk 19:42, 26 March 2014 (UTC)

Thank you for the link. I couldn't find an article like that.Inkan1969 (talk) 19:48, 26 March 2014 (UTC)

This (which assumes equal tension on each string) gives corresponding gauges in metres, and this table (from the same folks) gives gauges and mass per metre - note that these are for natural gut core strings; steel core strings will surely be quite different. -- Finlay McWalterჷTalk 20:10, 26 March 2014 (UTC)

These are tensions in the 40 to 80 N range, so not quite in to the hundreds. Guitar strings are tensioned to about double that. A pretty thorough list of tensions for various strings (for guitars and related instruments) is here. -- Finlay McWalterჷTalk 20:28, 26 March 2014 (UTC)

Clean burning

Are there any solids that burn entirely without leaving any leftovers on the surface they have been ignited at.

I know some liquids like alcohol might have such properties, but it what about solids? 91.77.160.11 (talk) 20:04, 26 March 2014 (UTC)

A thought in the right direction but not a full response. In order to leave no leftovers the combustion reaction would have ideally have to be a complete combustion, where all the reaction products are gas, which then disperses.

One class of solid materials which as far as I know undergo complete combustion to gas are explosives, However they do so sufficently quickly that they also take out the ignition surface.Sfan00 IMG (talk) 22:56, 26 March 2014 (UTC)

I agree that leaving no left-overs implies the reaction products are solely gases, but that's quite common: for example pure sulfur (solid) burns in oxygen to give sulfur dioxide (gas). Incidentally, some solids can completely dissociate into gases without burning: ammonium chloride (solid) becomes ammonia (gas) and hydrogen chloride (gas). --RexxS (talk) 23:09, 26 March 2014 (UTC)

Diamond, though again the fire will damage the fireplace. Jim.henderson (talk) 23:03, 26 March 2014 (UTC)

Nitrocellulose comes pretty close. Magicians use it as "flash paper" because after burning it leaves almost no visible ash or smoke. Nitrocellulose was also used as the basis for early types of smokeless powder, the lack of solid particulate in the combustion process is what makes the smokeless (since smoke is basically solid combustion products dispersed in air). --Jayron32 23:11, 26 March 2014 (UTC)

If you burn them hot enough, the solid hydrocarbons will produce only carbon dioxide and water vapor. (If you can't manage a hot enough flame, you get soot.) --Carnildo (talk) 02:59, 27 March 2014 (UTC)

Regarding the comment that only gases should be produced: I agree, but keep in mind that they may not be gases at room temperature, only at the combustion temperature. Water vapor is a good example, but there may be other products which are either liquids or solids at room temperature, but are vapors when they leave the fire. Of course, solids that then redeposit when they cool may not meet your standard for "clean burning", but liquids which recondense might, if they are clear and harmless, like water vapor. StuRat (talk) 03:12, 27 March 2014 (UTC)

As long as it's partial pressure remains below the vapor pressure, the water vapor produced during hydrocarbon combustion remains a vapor at ambient temperature as well. It wouldn't start condensing unless the air was locally at 100% relative humidity for the ambient temperature. --Jayron32 08:43, 27 March 2014 (UTC)

Right, but it will eventually condense somewhere, even if it has to wait for winter or travel to Antarctica. With water this isn't a problem, of course, as it still qualifies as "clean". StuRat (talk) 13:21, 27 March 2014 (UTC)

Ashless filter paper is specifically designed to burn without leaving a solid residue, for use in labs. shoy (reactions) 12:52, 27 March 2014 (UTC)

A lump of pure carbon, burned in a sufficient quantity of pure oxygen could only produce CO and CO2...right? You can only get compounds of carbon and oxygen formed from it - and CO and CO2 are the only two. The only other possibility is that you get some unburned carbon left behind (maybe as soot) - but if you're at the ignition temperature, that too will burn. So the resulting mix could only possibly contain O2, CO and CO2. I'm sure there are a bazillion other reactions for which that's true.

But if you're burning it in air - which is an incredibly complex mix of gasses, then there could be all sorts of other byproducts of combustion, and ruling out the possibility that any of those are not gasses would be tricky. So at some level, it's going to be hard to prove that you'd get perfect combustion with only gaseous byproducts with any solid material as the starting point...but at a practical level, I'm sure there are many, many combustion reactions that are "close enough". SteveBaker (talk) 14:46, 27 March 2014 (UTC)

Reversible cycle

A classic method of showing that the Carnot cycle has the maximum efficiency between two given temperatures depends on its reversibility.: If a more efficient heat cycle existed, the reversible Carnot cycle can be used as a heat pump to pump all the heat lost by the more efficient engine out of the heat dump and either use it as work or return it to the heat reservoir. But the two engines combined then form a 100% efficient perpetual motion machine. A more detailed explanation of that scenario is shown here. The Carnot+better combo can also be used to make heat flow from the colder dump to the warmer reservoir without any work.

Now a reversible cycle can be represented as a well defined closed loop on a P-V graph. Here's the Carnot graph. But what confuses me: Isn't ANY cycle that can be represented as a well defined closed loop on a P- V diagram a reversible cycle? Like the Otto cycle and the diesel cycle? Then is reversibility actually a property not exclusive to the Carnot cycle? Further, couldn't I then join a Carnot cycle with a less efficient but reversible cycle (with a well defined closed loop) to make a perpetual motion machine? Thank you in advance.Inkan1969 (talk) 20:22, 26 March 2014 (UTC)

Our article at Otto cycle states that this cycle comprises four distinct processes - two of them reversible and the other two occurring at constant volume but not reversible. Therefore I don't think it is correct to assume the Otto and the Diesel are reversible. Dolphin (t) 22:03, 26 March 2014 (UTC)

Clearly Otto is reversible, while Diesel is not, giving us leseiD if we attempt to reverse it. :-) StuRat (talk) 01:42, 27 March 2014 (UTC)

Wouldn't any cycle which starts with a chemical fuel need to produce that chemical fuel again in order to be fully reversible ? StuRat (talk) 01:42, 27 March 2014 (UTC)

The air standard cycles, such as Otto and Diesel, disregard the practicalities of where the heat comes from. In order to determine a thermodynamic efficiency, they simply postulate that there is an increase in temperature and pressure at a constant volume. An increase in temperature and pressure at a constant volume won't be reversible. (Good point about the palindrome.) Dolphin (t) 05:52, 27 March 2014 (UTC)

I thought Palindrome is the other name for Wasilla Airport? ;-) 24.5.122.13 (talk) 06:33, 27 March 2014 (UTC)