Neuropsychobiology of affective disorders. Some methodological considerations

Amine hypothesis is neither an adequate nor a sufficient postulate in understanding the neuropsychobiology of affective disorders. Interactions and balance between various mechanisms and factors may be important. Better techniques and methodology need to be used and a more comprehensive approach seems to be necessary in formulating meaningful research strategies. The present paper reexamines someaspects of the available data and suggests a few approaches in the sutdy and elucidation of neruophychobiology of affective disorders.     

Cooking at low temperatures: energy and time requirements

A flat plate solar collector can easily supply hot water at temperatures upto 90–95°C. At these temperatures, rice, potatoes and vegetables can be cooked without much difficulty. However, to design an efficient solar system for cooking, one must know the exact energy and time required for cooking at these temperatures. Our experiments show that the actual energy consumed in cooking rice, potatoes or green vegetables is only 0.06 to 0.10 kWh/kg at cooking temperatures of 82–88°C and the cooking time at these temperatures is 30–45 min.     

Error Probability of a Binary Signal Perturbed by Intersymbol Interference and Impulsive Atomopheric Noise

This paper analyzes the performance of baseband polar signals in the presence of impulsive atmospheric noise and intersymbol interference (ISI). Different levels of ISI have been considered to make the analysis more meaningful. Possible explanations for the results are offered. A comparison has also been made with the system operating in Gaussian noise.     

Multilevel difference schemes for the heat conduction equation and its application to the dirichlet problem in two and three dimensions

In this paper we have discussed a general method of deriving high order multilevel schemes for the heat conduction equation in higher dimensions. The application of the three level parabolic schemes for the solution of the steady state Dirichlet problem in two and three dimensions is discussed by introducing two parameters. The error bounds given by Hadjidimos are further refined which drastically reduces the theoretical estimate of the number of iteration cycles required for a given accuracy η. We have also defined a new set of iteration parameters. A numerical example is computed and it is seen that the present methods produce accurate results.     

Binary baseband polar signals in combination with continuous and impulsive noise with i.s.i.

This letter presents the performance of a binary baseband polar system in the presence of a mixture of continuous and impulsive noise and intersymbol interference (i.s.i.). The results obtained are very general and the system performance in special cases like purely continuous noise or purely impulsive noise with or without i.s.i. can be easily derived from the general results.     

Critical magnetic fields of Cu-Pb-Cu proximity-effect sandwiches studied by acoustic surface waves

The temperature dependence of the surface-wave attenuation in Cu-Pb-Cu sandwiches, in the absence of a magnetic field, agrees well with the BCS expression. We compare the temperature dependence of the parallel and perpendicular critical fields with expressions derived from the Ginzburg-Landau theory. We get satisfactory agreement, provided that for the thinner specimens we take the mean free paths in the proximity-effect sandwich to be somewhat smaller than the values found for monitor strips. This implies that some interdiffusion between the Pb and the Cu is taking place.     

Validity studies in clustering methodologies

Clustering algorithms tend to generate clusters even when applied to random data. This paper provides a semi-tutorial review of the state-of-the-art in cluster validity, or the verification of results from clustering algorithms. The paper covers ways of measuring clustering tendency, the fit of hierarchical and partitional structures and indices of compactness and isolation for individual clusters. Included are structural criteria for validating clusters and the factors involved in choosing criteria, according to which the literature of cluster validity is classified. An application to speaker identification demonstrates several indices. The development of new clustering techniques and the wide availability of clustering programs necessitates vigorous research in cluster validity.     

Carbothermal reduction synthesis of nanocrystalline zirconium carbide and hafnium carbide powders using solution-derived precursors

Zirconium carbide (ZrC) and hafnium carbide (HfC) powders were produced by the carbothermal reduction reaction of carbon and the corresponding metal oxide (ZrO₂ and HfO₂, respectively). Solution-based processing was used to achieve a fine-scale (i.e., nanometer-level) mixing of the reactants. The reactions were substantially completed at relatively low temperatures (<1500°C) and the resulting products had small average crystallite sizes (50–130 nm). However, these products contained some dissolved oxygen in the metal carbide lattice and higher temperatures were required to complete the carbothermal reduction reactions. Dry-pressed compacts prepared using ZrC-based powders with 100 nm crystallite size could be pressurelessly sintered to 99% relative density at 1950°C.     

A novel converter topology for multiple individually regulated outputs

Power supply voltages in digital systems have reduced considerably in recent years, and often digital components requiring different voltages are present on the same board. This has increased the demand for multiple output power distribution systems with tight individual load voltage regulation. This paper presents a power distribution system having a central power supply that acts as a controlled current source whose output is connected to individual loads on a time shared basis. All the magnetics are concentrated in the converter acting as the current source. The current source can be realized by a current controlled buck, buck-boost, or single-ended primary inductance converter (SEPIC). First, a comparative analysis of buck, buck-boost, and SEPIC based implementation of the current source is carried out. Next, a buck-based current source implementation with constant frequency pulse-width modulation control for the output voltages is described. Detailed component and control design, simulations, and experimental results for a 100-W prototype are presented.