Existence Of Certain Relations Research Articles

Dependence of Transformation of Intrinsic Rhythmic Impulse Activity of Neurons on Spatio-Temporal Organization of Synaptic Actions on Dendrites: A Simulation Study

The aim of the study to elucidate the biophysical mechanisms able to determine specific transformations of the patterns of output signals of neurons (neuronal impulse codes) depending on the spatio-temporal organization of synaptic actions coming to the dendrites. We studied mathematical models of the neocortical layer 5 pyramidal neurons built according to the results of computer reconstruction of their dendritic arborizations and experimental data on the voltage-dependent conductivities of their dendritic membrane. This work is a continuation of our previous studies that showed the existence of certain relations between the complexity of neural impulse codes, on the one hand, and the complexity, size, metrical asymmetry of branching, and nonlinear membrane properties of the dendrites, on the other hand. This relation determines synchronous (with some phase shifts) or asynchronous transitions of asymmetrical dendritic subtrees between high and low depolarization states during the generation of output impulse patterns in response to distributed tonic activation of dendritic inputs. In this work we demonstrate the first time that the appearance and pattern of transformations of complex periodical impulse trains at the neuron’s output associated with receiving a short series of presynaptic action potentials are determined not only by the time of arrival of such a series, but also by their spatial addressing to asymmetric dendritic subtrees; the latter, in this case, may be in the same (synchronous transitions) or different (asynchronous transitions) electrical states. Biophysically, this phenomenon is based on a significant excess of the driving potential for a synaptic excitatory current in low-depolarization regions, as compared with that in high-depolarization dendritic regions receiving phasic synaptic stimuli. These findings open a novel aspect of the functioning of neurons and neuronal networks.

More Than the Sum of Its Parts: Meta-Analysis and Its Potential to Discover Sources of Heterogeneity in Psychosomatic Medicine

Meta-analyses may contribute to more reliable knowledge about the existence of certain relations in the area of psychosomatic research. Surprisingly, the increasing popularity of meta-analysis is not reflected in the number of meta-analyses of observational studies published in Psychosomatic Medicine. This may be due to the specific difficulties that apply to meta-analyses of observational research. The aim of this paper is to provide a nontechnical overview of the principles of meta-analysis applied to observational research. We will highlight general principles of meta-analysis and discuss the major threats to its validity, with an emphasis on its specific merits and pitfalls for psychosomatic research, using several examples. We conclude that meta-analysis is a relatively simple technique, leaving little reason for not routinely applying it when performing a systematic review. An adequately conducted meta-analysis may not only provide a summary estimate of a certain association, but it has additional value in discovering relevant confounders, mediators, and moderators, as well as identifying areas of research that require more attention.

Robust clusterwise linear regression through trimming

The presence of clusters in a data set is sometimes due to the existence of certain relations among the measured variables which vary depending on some hidden factors. In these cases, observations could be grouped in a natural way around linear and nonlinear structures and, thus, the problem of doing robust clustering around linear affine subspaces has recently been tackled through the minimization of a trimmed sum of orthogonal residuals. This “orthogonal approach” implies that there is no privileged variable playing the role of response variable or output. However, there are problems where clearly one variable is wanted to be explained in terms of the other ones and the use of vertical residuals from classical linear regression seems to be more advisable. The so-called TCLUST methodology is extended to perform robust clusterwise linear regression and a feasible algorithm for the practical implementation is proposed. The algorithm includes a “second trimming” step aimed to diminishing the effect of leverage points.

The chiral ring and the periods of the resolvent

The strongly coupled vacua of an N = 1 supersymmetric gauge theory can be described by imposing quantization conditions on the periods of the gauge theory resolvent, or equivalently by imposing factorization conditions on the associated N = 2 Seiberg–Witten curve (the so-called strong-coupling approach). We show that these conditions are equivalent to the existence of certain relations in the chiral ring, which themselves follow from the fact that the gauge group has a finite rank. This provides a conceptually very simple explanation of why and how the strongly coupled physics of N = 1 theories, including fractional instanton effects, chiral symmetry breaking and confinement, can be derived from purely semi-classical calculations involving instantons only.

Air Gasification of Biomass in a Downdraft Fixed Bed: A Comparative Study of the Inorganic and Organic Products Distribution

This paper deals with the gasification of agricultural residues such as almond shells and wood at high temperature (850 °C) in a small-scale gasification plant coupled with a reciprocated internal combustion engine. Detailed investigation of both organic (tar) and inorganic (NH3, HCN, metals, etc.) products distribution in the process streams are provided. This research aims to assess the existence of certain relations between feedstock composition and the observed products distribution in the steady state. Biomass feedstock is characterized for its elemental composition, its content of metallic species, and lignin, cellulose, and hemicellulose fractions. A different feedstock composition was found to be associated with some important variations in the process monitored parameters such as the gasification rate, the tar content, and the char yield in the flue gas. Also a relation was found between the relative amount of ammonia and cyanide species in the flue gas at the operating conditions of the gasifier (oxygen-to-biomass ratio and activated carbon support). Spectroscopic features of the sludgy condensate formed in the upper part of the gasifier during the early stage of the process together with the characterization of char, fly ash, and acidic species in the flue gas shed light on some mechanistic aspects of the gasification process.

The Isotope Effect in Line and Band Spectra

IN two recent letters to NATURE (March 29, p. 459, and April 19, p. 567) Nagaoka, Sugiura, and Mishima, and again in another letter in NATURE of April 12, p. 532, Nagaoka and Sugiura have pointed out the existence of certain relations, which they ascribe to isotopy, between the positions of more or less widely separated spectral lines. The present writer is concerned with these communications mainly because they may cause confusion in regard to two letters of his own to NATURE (March 22, p. 423, and April 5, p. 489) on the isotope effect in band spectra.

The Isotope Effect in Line and Band Spectra

IN two recent letters to NATURE (March 29, p. 459, and April 19, p. 567) Nagaoka, Sugiura, and Mishima, and again in another letter in NATURE of April 12, p. 532, Nagaoka and Sugiura have pointed out the existence of certain relations, which they ascribe to isotopy, between the positions of more or less widely separated spectral lines. The present writer is concerned with these communications mainly because they may cause confusion in regard to two letters of his own to NATURE (March 22, p. 423, and April 5, p. 489) on the isotope effect in band spectra.

Observations on the existence of certain relations between the mode of coloration of birds and their geographical distribution

(1874). Observations on the existence of certain relations between the mode of coloration of birds and their geographical distribution. Annals and Magazine of Natural History: Vol. 13, No. 74, pp. 180-182.