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Register a new userStudy on the multiple characteristics of M3 generation of pea mutants obtained by neutron irradiation
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Irradiation breeding is an important technique in the effort to solve food shortages and improve the quality of agricultural products. In this study, a field test was implemented on the M3 generation of two mutant pea plants gained from previous neutron radiation of pea seeds. The relationship between agronomic characteristics and yields of the mutants was investigated. Moreover, differences in physiological and biochemical properties and seed nutrients were analyzed. The results demonstrated that the plant height, effective pods per plant, and yield per plant of mutant Leaf-M1 were 45.0%, 43.2%, and 50.9% higher than those of the control group. Further analysis attributed the increase in yield per plant to the increased branching number. The yield per plant of mutant Leaf-M2 was 7.8% higher than that of the control group, which could be related with the increased chlorophyll content in the leaves. There was a significant difference between the two mutants in the increase of yield per plant owing to morphological variation between the two mutants. There were significant differences in SOD activity and MDA content between the two mutants and the control, indicating that the physiological regulation of the two mutants also changed. In addition, the iron element content of seeds of the two mutants were about 10.9% lower than in the seeds of the control group, a significant difference. These findings indicate that the mutants Leaf-M1 and Leaf-M2 have breeding value and material value for molecular biological studies.
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The paper is devoted to the results of the EAS neutron component investigations by means of the PRISMA-32 array. The array consists of 32 en-detectors and enables to record delayed thermal neutrons accompanying showers. For registration of thermal neutrons, the scintillator based on $^{6}Li$ isotope as a target is used in the detectors. Some results of the processing of data accumulated over a long period of time are presented: the lateral distribution function of neutrons in EAS and preliminary results on EAS neutron multiplicity spectrum and distribution of showers in e/n ratio.
The effects of neutron irradiation on normal state and superconducting properties of epitaxial magnesium diboride thin films are studied up to fluences of 1020 cm-2. All the properties of the films change systematically upon irradiation. Critical temperature is suppressed and, at the highest fluence, no superconducting transition is observed down to 1.8 K. Residual resistivity progressively increases from 1 to 190 microohmcm; c axis expands and then saturates at the highest damage level. We discuss the mechanism of damage through the comparison with other damage procedures. The normal state magnetoresistivity of selected samples measured up to high fields (28 and 45T) allows to determine unambiguously the scattering rates in each band; the crossover between the clean and dirty limit in each sample can be monitored. This set of samples, with controlled amount of disorder, is suitable to study the puzzling problem of critical field in magnesium diboride thin films. The measured critical field values are extremely high (of the order of 50T in the parallel direction at low fluences) and turns out to be rather independent on the experimental resistivity, at least at low fluences. A simple model to explain this phenomenology is presented.
This is a supplement to the paper arXiv:q-bio/0701050, containing the text of correspondence sent to Nature in 1990.
Some mechanisms of cardiac arrhythmias can be presented as a composition of elementary acts of block and reflection on the contacts of homogeneous areas of the conducting tissue. For study this phenomena we use an axiomatic one-dimensional model of interaction of cells of excitable tissue. The model has four functional parameters that determine the functional states durations of the cell. We show that the cells of a homogeneous excitable tissue, depending on the ratio of the durations of the functional intervals, can operate in the mode of solitary waves conduction or in one of three modes of selfgeneration. It is proved that the propagation of a solitary wave through the boundary of homogeneous conducting tissues can be accompanied by a block or multiplex reflection. Block and reflection are unidirectional phenomena, and there are not compatible on the same boundary. Systematized rules of transmitting, block and reflection waves at the boundary of homogeneous conducting tissues open up new possibilities for design mechanisms of generation and analyzing complex heart rate patterns.
It is known that the Arrhenius equation, based on the Boltzmann distribution, can model only a part (e.g. half of the activation energy) for retinal discrete dark noise observed for vertebrate rod and cone pigments. Luo et al (Science, 332, 1307-312, 2011) presented a new approach to explain this discrepancy by showing that applying the Hinshelwood distribution instead the Boltzmann distribution in the Arrhenius equation solves the problem successfully. However, a careful reanalysis of the methodology and results shows that the approach of Luo et al is questionable and the results found do not solve the problem completely.
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