Bayesian Nonparametric Modeling for Comparison of Single-Neuron Firing Intensities

Summary .  We propose a fully inferential model-based approach to the problem of comparing the firing patterns of a neuron recorded under two distinct experimental conditions. The methodology is based on nonhomogeneous Poisson process models for the firing times of each condition with flexible nonparametric mixture prior models for the corresponding intensity functions. We demonstrate posterior inferences from a global analysis, which may be used to compare the two conditions over the entire experimental time window, as well as from a pointwise analysis at selected time points to detect local deviations of firing patterns from one condition to another. We apply our method on two neurons recorded from the primary motor cortex area of a monkey's brain while performing a sequence of reaching tasks.     

Evaluation of early generations for iron chlorosis in relation to productivity in groundnut (Arachis hypogaea L.)

Five popular but iron-inefficient cultivars were crossed with three efficient genotypes and both parents and F₁s were evaluated for iron-efficiency in potted calcareous and noncalcareous soil. The iron-efficient genotypes were dark green or green in both noncalcareous and calcareous soils whereas inefficient types were light green to yellow in calcareous soil. The chlorophyll and active iron (Fe²⁺) concentration of leaves was less in iron-efficient genotypes compared to efficient types in calcareous soil and reduction of both the parameters from noncalcareous to calcareous soil was considerably high in iron-inefficient lines. There was significant correlation between visual scores, chlorophyll and active iron content. There were no differences among F₁s for iron chlorosis and they were all iron-inefficient. The frequency of iron-inefficient plants was higher than the efficient plants in all F₂ populations. But most of the productive plants came from iron-efficient segregants indicating strong association between iron-efficiency and productivity. Based on the results selection for iron-efficiency in early generations and extensive evaluation for productivity in advanced generations is suggested for developing varieties for cultivation in calcareous soils.     

The lifetime of molecular (Davydov) solitons

The lifetime of Davydov solitons in a one-dimensional system is studied theoretically. The process of thermalization and the properties of solitons at finite temperature are investigated and the processes of soliton creation and disintegration are discussed.     

Effects of Organic Solvents on the Coupling Between ATP Hydrolysis and Sliding of Microtubules in Axonemes from Chlamydomonas Flagella

ABSTRACT. The effects of organic solvents on the ATPase activity and the sliding disintegration of axonemes from Chlamydomonas were investigated. The axonemal ATPase was markedly activated by methanol accompanying with marked inhibition of the sliding disintegration of axonemes. On the contrary, glycerol inhibited the ATPase activity without serious inhibition of the sliding disintegration. As far as the axonemes are not irreversibly denatured by extremely high concentration of solvents, the effects of solvents both on the ATPase and the ability of sliding are reversible. Therefore, the inhibition of sliding accompanied by the activation of ATPase is probably due to an inability to couple the hydrolysis of ATP to sliding between dynein and microtubule in the presence of methanol. The axonemal ATPase was less sensitive to vanadate inhibition after exposure to methanol. This indicates that methanol makes the dyneinADP.Pi complex unstable and increases product release. On the other hand, glycerol and ethylene glycol seem to stabilize the force generation responsible for the sliding through stabilizing the dynein.ADP.Pi complex.     

Pattern formation underlying phytochrome-mediated anthocyanin synthesis in the cotyledons ofSinapis alba L.

The ability to respond to phytochrome (P_fr, the far-red light absorbing from of phytochrome) with anthocyanin synthesis appears first in some marginal regions of the abaxial epidermis of the mustard cotyledons and from there spreads gradually over the entire tissue (transient phase). The pertinent pattern is independent of environmental influences such as light quality and nutritional culture conditions. The competence for P_fr in the epidermal cells, with regard to the initial action of P_fr (concerning anthocyanin synthesis), appears considerably earlier than the ability for actual anthocyanin synthesis. An electron microscopical study of the ultrastructural changes occurring in vacuoles and plastids of the epidermal cells during the transient phase showed that a correlation only exists between the differentiation of central cell vacuoles, originating from the aleurone vacuoles, and the appearance of the ability to accumulate anthocyanin. It is suggested that the formation of a central cell vacuole is a prerequisite for anthocyanin accumulation in the epidermal cells of the mustard seedling cotyledons.Abbreviations P_r, P_fr red and far-red absorbing forms of phytochrome - HS Hoagland's nutrient solution     

The forensic use of luminol chemiluminescence to detect traces of blood inside motor vehicles.

The luminol test for blood was carried out on a set of interior fittings and surfaces inside three different makes of modern motor car. The surfaces and fittings provided little interference with the test for blood, although there was some detectable chemiluminescence when the test was applied to blood-free material from a seatbelt, a boot-lining and a gear-knob. The case with which haemoglobin samples could be washed off interior car surfaces was also examined for seat fabrics, carpets, roof-linings and various other plastic interior surfaces. A standard wash with water alone was not very effective and removed only ca. 50% of the haemoglobin. A standard wash with soapy water or with a proprietary multipurpose car cleaner removed ca. 90% of the haemoglobin from the tested surface. The effect of high car interior temperatures on haemoglobin samples that were subsequently used in the luminol test was also examined. It was shown that the sensitivity of the luminol test was not decreased but was increased by the prior heating of a haemoglobin sample. This effect was attributed to the thermal conversion of haemoglobin to the more brighter catalyst for chemiluminescence, methaemoglobin. The enthalpy of this conversion in the solid state was found to be 14.1 kJ/mol.