User:Jclerman/sandbox5

All references quoted and linked in the preceding discussion have been studied and 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 17:20, 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.

time equation
$$ t = \frac{1}{\lambda} {\times} {\ln \left(1+\frac{D}{P}\right)}

$$

where


 * $$ t = $$age of the sample
 * $$ D = $$number of atoms of the daughter
 * $$ P = $$number of atoms of the parent
 * $$ \lambda = $$decay constant
 * $$ ln = $$natural logarithm