User talk:Teply

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Welcome!

Hello, Teply, and welcome to Wikipedia! Thank you for your contributions. I hope you like the place and decide to stay. Here are a few good links for newcomers:

I hope you enjoy editing here and being a Wikipedian! Please sign your name on talk pages using four tildes (~~~~); this will automatically produce your name and the date. If you have any questions, check out Wikipedia:Where to ask a question or ask me on my talk page. Again, welcome! Shimgray | talk | 17:54, 25 September 2005 (UTC)

1 DYK
2 Your article, ANTARES, was selected for DYK!
3 Exponential decay
4 LD50 and Time Constant
5 Physics
6 re Biological half-life
7 Exponential decay (continued)
8 Phase velocity of matter wave

[edit] DYK

Did you know? has been updated. A fact from the article Science Service, which you recently created, has been featured in that section on the Main Page. If you know of another interesting fact from a recently created article, then please suggest it on the "Did you know?" talk page.

[edit] Your article, ANTARES, was selected for DYK!

On June 11, Did you know? was updated with a fact from the article ANTARES, which you created. If you know of another interesting fact from a recently created article, then please suggest it on the "Did you know?" talk page.

Thanks for your contributions! ++Lar: t/c 02:11, 11 June 2006 (UTC)

[edit] Exponential decay

I am not sure how to cite this. From what I can tell, mean lifetime really is replacing the notion of half-life.

Where? In general? In math? In electric engineering? In physics of particles? In biology? In ...?

Sure, this is a bit of a general impression. But I doubt I can find any single source that can verify it.

A single source won't do it when you cite opinions rather than facts.

My impression comes from all of the textbooks I have read and all of the professors who have taught me.

Again subjective. My "all" sets (of books and professors) might be smaller or larger than yours and that those of the wikipedia users.

As a matter of fact, I am pretty sure that I have read something directly declaring, "A few older authors on this subject may refer to half-life instead of mean lifetime. Half-life is an outdated term related to the mean lifetime by [formula]."

Don't put quotation marks if it's not a verbatim text AND if you can't provide a verifiable source. When you become a practicing scientist and submit a paper for publication it will be rejected if a quotation is not duly sourced.

I will try to look for the source.

Good. Please, send me scans.

Please help me if you have any better ideas.

I'm trying, that's why I commented on your edits and in your new paragraph (below).

Teply 05:55, 11 June 2006 (UTC)

Jclerman 12:15, 11 June 2006 (UTC)

I just looked in the introductory physics textbooks that I had around, namely Tipler & Mosca Physics for Scientists and Engineers and Tipler & Llewellyn Modern Physics.

Unfortunately my university library does NOT have these texts. They refuse to purchase market oriented editions that make annual or biannual trivial changes in order to be able to sell frequently updated texts rather than let students rely on "used books". And I have NOT been able to get them from the publisher unless I can prove that I have adopted them for my classes. And Wikipedia does NOT qualify as a class because the definition of a class is "some 40 copies sold". Furthermore, you should try to use better rooted in time and more advanced references, if possible written by practicing scientists. Real world editors of scientific journals wiil require that from you when the time arrives.

Tipler & Mosca uses the mean lifetime for damped harmonic oscillators and RC circuits.

Mean lifetime of what? Not of the oscillator or the circuit. I'd like to see a scan.

Tipler & Llewellyn introduces mean lifetime in the very first chapter without any mention of half-life whatsoever in its discussion of muon decay as an example experiment for special relativity.

Why would they? Would it have meaning for a muon? Sorry if this appears to be a quiz. It's my long established teaching style. To ask questions rather than to repeat answers.

In both books, the section on nuclear decay mentions both mean lifetime and half-life, but the mean lifetime is introduced first with the half-life written in terms of mean lifetime.

Correct. It should be evident why, don't you see it? Then the half-life can both be defined and described. Defined as a half of something and described as related to something else. It might not be obvious before spending some time in an isotopes lab. And up to now we've covered only two narrow branches of physics, and maybe one of nuclear engineering.

Although the Wikipedia article for damped harmonic oscillators is rather messy and does not really mention either one, the article on RC circuits strictly uses mean lifetime.

I can't find the expression mean lifetime in the RC circuit article. Moreover I wouldn't know the lifetime of what you refer to. Of the circuit? Please, be precise.

I do admit, however, that I have more or less ignored biological applications. Acute toxicity, for example, is often gauged by measuring the amount of poison needed to kill half (on average) of a sample of lab rats.

If you try to refer to the quantity LD-50, how would it relate to half-life or mean lifetime? Am I missing something in your comment?

Unfortunately, that article is still a stub, but general systems of biological halflife (yes, the misspelling is there, and I am in the process of trying to have it moved back to biological half-life) certainly use the notion of half-life.

Yes, it does. It probably lacks (as most other related articles) to clearly state why and when the quantity called half-life is important.

I will try to make the distinction between the physics/engineering mean lifetime and the biology half-life tomorrow morning. Teply 06:55, 11 June 2006 (UTC)

Try to do it after reviewing my comments and questions, so we can avoid further iterations. You might want to try a draft text in this discussion page so we can discuss it before moving it to the article page. And, please, send me scans of your supporting texts. Jclerman 13:11, 11 June 2006 (UTC)

[edit] LD50 and Time Constant

I just made a key discovery, the time constant article. It explains that it is the time it takes for 1-1/e=63.2% of the system's step response, and even discusses the time constant for the RC circuit and the RL circuit. This basically is the mean lifetime. This had been part of my rationale behind declaring the mean lifetime to be more common. Should we consider some kind of merger? The articles do not even mention each other as of this moment. And thank you for mentioning LD50. I was having one of those forgetful moments where I could not think of the term I wanted to use. LD50 is the dosage needed to reach the half-life of lab animals. "Ideally" - though the model rarely acts like a simple exponential decay - doubling the dosage would leave only 25% of the original animals alive, tripling it would only leave 12.5%, etc. Teply 14:13, 11 June 2006 (UTC) Retrieved from "http://en.wikipedia.org/wiki/User_talk:Jclerman"

Unless you tell me "lifetime of what", I don't understand why you insist on the electric circuit lifetime. Same formula, same exponential equation, don't mean the same concept.
And LD50 has nothing to do with times and exponentials. And not even with half lives.

Please keep things separated. I made some of the crucial changes. I still think you should "sandbox" your edits here. Cordially, J.C.Lerman

Jclerman 15:17, 11 June 2006 (UTC)

[edit] Physics

Actually, my experience in school wasn't that great, and I've been turned off to physics, as have a few of the other physics majors that were in my class. I'll probably go into some other field in grad school. One of the other students is actually going into literature now. — BRIAN0918 • 2006-06-11 18:52

[edit] re Biological half-life

Biological halflife was moved to Biological half-life per your request at WP:RM. Regards, Ganeshk (talk) 19:37, 15 June 2006 (UTC)

[edit] Exponential decay (continued)

I am not sure how to cite this. From what I can tell, mean lifetime really is replacing the notion of half-life. Sure, this is a bit of a general impression. But I doubt I can find any single source that can verify it. My impression comes from all of the textbooks I have read and all of the professors who have taught me. As a matter of fact, I am pretty sure that I have read something directly declaring, "A few older authors on this subject may refer to half-life instead of mean lifetime. Half-life is an outdated term related to the mean lifetime by [formula]." I will try to look for the source. Please help me if you have any better ideas. Teply 05:55, 11 June 2006 (UTC)

I just looked in the introductory physics textbooks that I had around, namely Tipler & Mosca Physics for Scientists and Engineers and Tipler & Llewellyn Modern Physics. Tipler & Mosca uses the mean lifetime for damped harmonic oscillators and RC circuits. Tipler & Llewellyn introduces mean lifetime in the very first chapter without any mention of half-life whatsoever in its discussion of muon decay as an example experiment for special relativity. In both books, the section on nuclear decay mentions both mean lifetime and half-life, but the mean lifetime is introduced first with the half-life written in terms of mean lifetime. Although the Wikipedia article for damped harmonic oscillators is rather messy and does not really mention either one, the article on RC circuits strictly uses mean lifetime. I do admit, however, that I have more or less ignored biological applications. Acute toxicity, for example, is often gauged by measuring the amount of poison needed to kill half (on average) of a sample of lab rats. Unfortunately, that article is still a stub, but general systems of biological halflife (yes, the misspelling is there, and I am in the process of trying to have it moved back to biological half-life) certainly use the notion of half-life. I will try to make the distinction between the physics/engineering mean lifetime and the biology half-life tomorrow morning. Teply 06:55, 11 June 2006 (UTC)

I just made a key discovery, the time constant article. It explains that it is the time it takes for 1-1/e=63.2% of the system's step response, and even discusses the time constant for the RC circuit and the RL circuit. This basically is the mean lifetime. This had been part of my rationale behind declaring the mean lifetime to be more common. Should we consider some kind of merger? The articles do not even mention each other as of this moment. And thank you for mentioning LD50. I was having one of those forgetful moments where I could not think of the term I wanted to use. LD50 is the dosage needed to reach the half-life of lab animals. "Ideally" - though the model rarely acts like a simple exponential decay - doubling the dosage would leave only 25% of the original animals alive, tripling it would only leave 12.5%, etc. Teply 14:13, 11 June 2006 (UTC)

Thanks so far for your help and suggestions. Here is the scan of the Tipler & Llewellyn example on muon decay. Note that this is the first chapter. And this is a table from the appendix of a somewhat more advanced particle physics textbook, Martin & Shaw Particle Physics of the Manchester Physics Series. Some of the studies as far back as the 1960 used mean lifetime to analyze pion decay.[1][2]. Understandably, muons and pions are subatomic matters. Although the half-life is certainly traditional for atomic - in particular nuclear - matters, mean lifetime is now replacing it in the most recent publications. A Google Scholar search for half-life reveals that virtually its only remaining use is in biology. But I have also found evidence that mean liftime is wiggling its way into advanced biology. Examples include the case of mean lifetime fecundity and fertility, where tables are clearly in terms of mean lifetime, and the case of fluorescence in tissues, where one paper discusses the topic not only in terms of exponential decay but also in terms of double exponential decay. Teply 06:55, 11 June 2006 (UTC)

All references quoted and linked in the preceding discussion have been studied and are commented upon in the following text. I expect it to be clear in which context each one of the different terms is used, and why. In summary, the hypothesized time and/or discipline dependent trends are not validated by the references quoted in their support.

Jclerman 18:40, 17 June 2006 (UTC)


The discussion has been grouped, by 
similarity of usage and applications,
in sections numbered 1 to 7, below.

To facilitate their scrutiny by the 
readers, each item has brief identifier 
key-codes that will allow me to locate 
the corresponding file with the full 
article or other referenced item and 
send it to interested readers. Just 
quote the first line of each item you 
would like to receive. 
    User:jclerman

1 ==========

Ch40.rtf - From Tipler's file that didn't 
transfer properly in MHT format. 
It uses half-life and decay constant or 
decay rate correctly. It deals with the
decay of atoms in a sample or volume, hence
it uses half-life correctly. Moreover, it 
is the quantity exrimentally measured in
such cases.
-
11-2c.pdf - More:Tipler. Production...sequential.
Uses mainly half-life, mean life, and 
mean lifetime correctly, indicating the 
conversion factors when it is preferrably
mathematically or more "ergonomic", to 
give the numerical value or a feeling for
the mean lifetime or average life.
-
11-3c.pdf - Energetics of alpha decay.
Uses half-life, correctly. See comments
in both previous items above.
-
12-3c.pdf - More:Tipler. Radiation...dosage.
Uses only half-life, correctly. See all 
comments above.
-
Research.mht - Explosive nucleosynthesis.
Uses half-life, correctly. See all comments
above.
-
Errata.pdf - Physical Chemistry Corrections
Replaces incorrect use of lifetime for 
corrected half-life. See all comments
above.

2 ==========

Munich2001-stretched.pdf - Application of 
the streched ...to fluorescence
Uses lifetime, correctly. It refers to, in 
imaging, visual extinction of image elements.
Half-lives wouldn't make any sense for such
an application. The experimentally observed 
quantity is, precisely, the vanishing of the 
ligth.
-
GetPDFServlet.pdf - Threshold states ...the CNO...
Uses lifetime, correctly. It refers to states,
not to the decay of a large number of atoms in 
a sample or volume. Half-life has no meaning
in such a context.
-
Resonances...States.pdf - More:Tipler Resonances
Uses lifetime and mean lives, correctly. See 
previous comment.

3 ==========

p384_1.pdf - Estimate ... meson. Blackie et al.
Uses lifetime, correctly. It refers to 
independent particles, not to atoms in a given 
volume. Half-life has no meaning in such a 
context. One can see its full life (and
measure the lifetime), e.g., in an emulsion 
plate or a particle chamber. 
-
p1014_1.pdf - Phys.Rev.123, 1014(1961) Glasser et al.
Mean Lifetime of the Neutral Pion.
Uses mean lifetime, correctly. See previous 
comments.
-
TL-muon decay.jpg - Scan by T, Muon decay fig.
Uses lifetime and mean lifetime, correctly.
See previous comments.
-
MS-particles table.jpg - Scan by T. Table
Uses mean life, correctly. See previous 
comments.

4 ==========

1471-2148-3-20.pdf - BMC Evolutionary Biology
Evolutionary experimentation .... Drosophila
Uses lifetime and mean lifetime, correctly.
Not only half-life of a fly can't be defined,
but it would as senseless as "ours". We live
for a duration called lifetime and our 
species (under specified conditions) has a
mean lifetime, but no half-life. Same for 
fecundity and fertility lifetimes. 
-
PubMed Central, Table 6 - Mean life-history 
of...Drosophila.
Uses mean lifetime fecundity and fertility.
Same comment as in previous example.

5 ==========

kuby6ech04[1].pdf - Antigens and antibodies.
Uses half-life, correctly, as pertaining to
the elimination half-life. See: J Clin Immunol. 
1986 May;6(3):256-64: Alterations in the 
half-life and clearance of IgG during therapy 
with intravenous gamma-globulin in 16 patients 
with severe primary humoral immunodeficiency. 
Schiff RI, Rudd C. Published studies of the 
metabolism of human IgG using trace amounts of 
radiolabeled IgG demonstrated that the elimination 
of native IgG followed first-order kinetics but 
that the half-life of IgG was shortest in patients 
with the highest serum concentrations of IgG. 

6 ==========

[[LD50]]

Not only it is not a half-life, but it is not a
even a "time".

7 ==========

Results from the Google Scholar search. .

a. Are not be interpreted as showing a slant towards 
biology usage of half-life. Before reaching such a 
conclusion one needs to normalize for the total 
number of articles (i.e. not only those using 
half-life) published in physics, chemistry, geology, 
hydrogeology, environmental pesticides, etc.  

b. Are not to be interpreted as showing a replacement
of other terms without constructing a time series for
each term intended. A search for half-life is not
relevant vis-a-vis a hypothesized replacement.

Note: These are only two objections. Let the reader 
find a couple more that also invalidate the google 
based arguments.

[edit] Phase velocity of matter wave

After some search, I noticed that the content of "Matter wave phase" was written by you. I'd like to discuss with you that, according to many sources including the Feynman lecture on Physics III (Quantum Mechanics) and here, the following formulas should be correct instead of those you wrote in the article:

$v_p = E/p = \hbar \omega / \hbar k = \omega/k$ ,