A DNA test to sex most birds.

There is a special reason for reviewing this book at this time: it is the 50th edition of a compendium that is known and used frequently in most chemical and physical laboratories in many parts of the world. Surely, a publication that has been published for 56 years, withstanding the vagaries of science in this century, must have had something to offer. There is another reason: while the book is a standard fixture in most chemical and physical laboratories, including those in medical centers, it is not as frequently seen in the laboratories of physician's offices (those either in solo or group practice). I believe that the Handbook can be useful in those laboratories. One of the reasons, among others, is that the various basic items of information it offers may be helpful in new tests, either physical or chemical, which are continuously being published. The basic information may relate

Handbook of Chemistry and Physics

We discuss an Adams-type predictor-corrector method for the numericalsolution of fractional differential equations. The method may be usedboth for linear and for nonlinear problems, and it may be extended tomulti-term equations (involving more than one differential operator)too.

https://ntrs.nasa.gov/api/citations/20020024453/downloads/20020024453.pdf

A Predictor-Corrector Approach for the Numerical Solution of Fractional Differential Equations

Alkanes, the major constituents of gasoline, diesel, and jet fuel, are naturally produced by diverse species; however, the genetics and biochemistry behind this biology have remained elusive. Here we describe the discovery of an alkane biosynthesis pathway from cyanobacteria. The pathway consists of an acyl-acyl carrier protein reductase and an aldehyde decarbonylase, which together convert intermediates of fatty acid metabolism to alkanes and alkenes. The aldehyde decarbonylase is related to the broadly functional nonheme diiron enzymes. Heterologous expression of the alkane operon in Escherichia coli leads to the production and secretion of C13 to C17 mixtures of alkanes and alkenes. These genes and enzymes can now be leveraged for the simple and direct conversion of renewable raw materials to fungible hydrocarbon fuels.

https://science.sciencemag.org/content/sci/329/5991/559.full.pdf

Microbial Biosynthesis of Alkanes

Optical Waveguide Theory

In recent years, wave splitting in conjunction with invariant imbedding and Green's function techniques has been applied with great success to a number of interesting inverse and direct scattering problems. The aim of the present paper is to derive a wave splitting for the Timoshenko equation, a fourth order PDE of importance in beam theory. An analysis of the hyperbolicity of the Timoshenko equation and its, in a sense, less physical relatives - the Euler-Bernoulli and the Rayleigh equations - is also provided.

/pdf/wave-splitting-of-the-timoshenko-beam-equation-in-the-time-3mla0nk6t2.pdf

Wave splitting of the Timoshenko beam equation in the time domain

In recent years, wave splitting in conjunction with invariant imbedding and
Green’s function techniques has been applied with great success to a number
of interesting inverse and direct scattering problems. The aim of the present
paper is to derive a wave splitting for the Timoshenko equation, a fourth
order PDE of importance in beam theory. An analysis of the hyperbolicity
of the Timoshenko equation and its, in a sense, less physical relatives—the
Euler-Bernoulli and the Rayleigh equations—is also provided.

/pdf/wave-splitting-of-the-timoshenko-beam-equation-in-the-time-41mhxut6yj.pdf

Colour constancy is the capacity of visual systems to keep colour perception constant despite changes in the illumination spectrum. Colour constancy has been tested extensively in humans and has also been described in many animals. In humans, colour constancy is often studied quantitatively, but besides humans, this has only been done for the goldfish and the honeybee. In this study, we quantified colour constancy in the chicken by training the birds in a colour discrimination task and testing them in changed illumination spectra to find the largest illumination change in which they were able to remain colour-constant. We used the receptor noise limited model for animal colour vision to quantify the illumination changes, and found that colour constancy performance depended on the difference between the colours used in the discrimination task, the training procedure and the time the chickens were allowed to adapt to a new illumination before making a choice. We analysed literature data on goldfish and honeybee colour constancy with the same method and found that chickens can compensate for larger illumination changes than both. We suggest that future studies on colour constancy in non-human animals could use a similar approach to allow for comparison between species and populations.

/pdf/quantitative-studies-of-animal-colour-constancy-using-the-1pksanki3o.pdf

Quantitative studies of animal colour constancy: using the chicken as model.

Recent studies have shown that sperm chemotaxis critically involves the human olfactory receptor OR1D2, which is activated by the aromatic aldehyde bourgeonal. Given that both natural and sexual selection may act upon the expression of receptors, we hypothesized that human males are more sensitive than human females for bourgeonal. Using a 3-alternative forced-choice test procedure, olfactory detection thresholds were determined for a total of 500 subjects, 250 males, and 250 females between 18 and 40 years of age. We found that male subjects detected bourgeonal at significantly lower concentrations (mean value: 13 ppb) compared with female subjects (mean value: 26 ppb), whereas no such gender difference in olfactory sensitivity was found with helional, a structural analog of bourgeonal, and with n-pentyl acetate, an aliphatic ester, which were tested in parallel. Males and females did not differ in their frequency of specific anosmia for any of the 3 odorants. The frequency distributions of olfactory detection thresholds were monomodal with all 3 odorants in both genders. Olfactory detection thresholds did not differ significantly between pre- and postovulatory females with any of the 3 odorants. To the best of our knowledge, this is the first study ever to find a human male superiority in olfactory sensitivity. Single nucleotide polymorphisms and/or copy number variations in genes coding for olfactory receptors may be the proximate cause for our finding, whereas a gender difference in the behavioral relevance of bourgeonal may be the ultimate cause.

/pdf/human-male-superiority-in-olfactory-sensitivity-to-the-sperm-41fy7m5z7u.pdf

Human Male Superiority in Olfactory Sensitivity to the Sperm Attractant Odorant Bourgeonal

Nasal mucosal blood flow was investigated in patients undergoing a stellate ganglion blockade. Elimination of the sympathetic neurogenic control did not affect the resting blood flow in the mucosa, as registered with the 133Xe washout technique. This indicates that the basal sympathetic vasoconstrictor activity is low in the mucosal vessels that regulate blood flow. With laser doppler flowmetry, the normal pattern of spontaneous oscillations in blood flow was seen to be altered following stellate ganglion blockade. This suggests that vasomotion in the mucosa is partly dependent on sympathetic neurogenic activity. Furthermore, the decrease in blood flow normally induced by a peripheral cold provocation could not be elicited after the ganglion blockade, which means that the decrease is mediated by sympathetic vasoconstrictor fibres.

Peter Olsson

Papers

Wave splitting of the Timoshenko beam equation in the time domain

Wave splitting of the Timoshenko beam equation in the time domain

Quantitative studies of animal colour constancy: using the chicken as model.

Human Male Superiority in Olfactory Sensitivity to the Sperm Attractant Odorant Bourgeonal

Sympathetic neurogenic control of blood flow in human nasal mucosa.