Background.
Studying the reproductive ability of black currant cultivars after long-term cryopreservation of their pollen in liquid nitrogen is very important for plant diversity conservation and for ...the effectiveness of breeding efforts.
Materials and methods.
Five black currant cultivars served as the material for the research. The viability of black currant pollen after cryopreservation in liquid nitrogen was analyzed. Pollen viability was tested on an artificial medium containing 10% of sucrose and 0.8% of agar. The viability of pollen was tested on the black currant collection at Pushkin and Pavlovsk Laboratories of VIR. The cultivar ‘Andreevskaya’ (k-15630) was pollinated with pollen stored for one year in liquid nitrogen (–196°C) as well as with fresh pollen (control test).
Results and conclusion
. After 12 months of conservation under ultralow temperatures there was a change in the level of pollen viability depending on the genotype: it varied from 10.4% (cv. ‘Pozdnyaya poslevoennaya’, k-7654) to 50.4% (cv. ‘Kriviai’, k-42517), while its mean value was 0.9% higher than the mean initial viability. The fruit setting rate in the control option was 81.3–94.2%. When pollinated with pollen kept in liquid nitrogen for one year, the fruit setting rate varied from 69.2% (‘Kacha’, k-44185) to 93.3% (‘Belorusochka’, k-41978); the remaining cultivars (‘Pozdnyaya poslevoennaya’; ‘Chereshneva’, k-42481; and ‘Kriviai’) demonstrated intermediate values of this indicator, i.e., the reproductive ability of pollen after cryopreservation was high even despite its low viability. As for the fruit weight, no differences were shown by cvs. ‘Kacha’, ‘Chereshneva’ and ‘Kriviai’ in both pollination options, while this indicator in cvs. ‘Belorusochka’ and ‘Pozdnyaya poslevoennaya’ was lower than the control by 0.31 and 0.24 g, respectively.
The options of relative motion of a homing object with a semi-passive method and a mobile end waypoint are considered. For the given options, estimates for the required transverse acceleration of the ...homing object and the miss distance are given. It is shown that to reduce the miss in homing by method of proportional guidance it is advisable to reduce the time for the control force formation, and the decrease of distance of switching off the control system, when in the object control system only angular information about the current position of the end way points and motion parameters of their own mass center is used.
Rheoreaction of the downstream migrating smolts of the European river lamprey was studied in the experimental conditions at illuminations of day and night intensity. It was found that at the daytime ...the smolts are mostly dormant and if move downstream then in active-passive form (with the head against the stream, and their speed going beyond the velocity). This data is well within the findings on the night downstream migration of the smolts during the 24h period in natural conditions. Thus, the downstream migration of the smolts has an active form.
Evolution of schooling behavior in fish is discussed. For the first time, schooling was formed in early Teleostei ca 200–220 Ma years BP. There are no strict data on the presence of this form of ...social behavior in older Craniata. It is supposed that the evolutionary path of schooling followed from asociality to protoschools and then to true equipotential schools. The schooling behavior might disappear and appear again repeatedly and independently in different groups of teleosteans. Formation of schooling depended on Teleostei’s mode of life, first of all, on distribution to the pelagial, and it did not strictly depend on the evolutionary age or phylogenetic relationships of taxonomic groups or particular species. Schooling might be transformed into other types of social behavior. The scheme of evolution of the schooling behavior is suggested.
The issue of high-current electron-beam transport in the LIA-5 accelerator is discussed. The results of numerical simulation of beam transport in the 15-m-long LIA-5 accelerator channel are ...presented. The ASTRA macroparticle (PIC) code and two codes developed at the Budker Institute of Nuclear Physics (a code based on the solution of the Kapchinsky–Vladimirsky system of equations (K–V envelope code) and the UltraSAM code implementing the method of boundary integral equations) are used in this simulation. The experimental data agree closely with the simulation results. The electron-beam envelope is reconstructed based on the experimental luminophore data using the K–V envelope code with a genetic algorithm.
Small freshwater (resident) populations of the European river lamprey
Lampetra
fluviatilis
from an isolated from the sea upper part of a river system with numerous lakes (the upper reaches of ...tributaries of the Daugava River and Lake Peipus, Pskov Oblast, Russia) have been studied. Adult individuals of the lamprey have been attributed to common and large size groups; adults are similar to other resident lamprey from the Baltic Sea basin. The presence of larvae of different size and age groups indicates regular spawning of the European river lamprey in the studied watersheds. Analysis of the modern and historical (before the isolation) distribution of lamprey revealed a reduction in habitats and a decrease in the number of individuals. Dam-associated disruption of migration routes led to the disappearance of anadromous form, and consequently, disappearance of resident lamprey from most of the studied waterbodies. We attribute the decrease in the number of rivers inhabited by lamprey and abundance of the lamprey both to anthropogenic factors (direct blocking of an access of anadromous form of the lamprey to spawning grounds by hydraulic construction) and to the characteristics of the studied area. The richness of the river system with lentic waterbodies makes it suitable for lamprey inhabitation with an influx of large anadromous individuals capable of crossing such reservoirs in search of spawning sites.
A task of modeling individual mental features of a decision-maker using a Fourier holography setup is considered. The problem is considered for a situation when current conditions of decision-making ...contradict to the previously learned rule of decision-making logic modeled by the non-cooperative game "Prisoner's Dilemma". The approach to the problem is based on a hypothesis of the correlation between mental features and the properties of the neural network as a material carrier of intelligence. The 6f Fourier holography scheme of the resonant architecture is considered as a three-layer neural network implementing a neuro-physiologically motivated concept of the "excitation ring" proposed by A.M. Ivanitsky. We analytically assess the dependence of the validity limits of the classical total probability formula for a disjunction of incompatible events on the characteristics of low-frequency filters in holograms and the correlation radii of the training image of the basic decision rule. Analytical results are confirmed by results of the numerical simulation.
The results of numerical modeling of the influence of the main factors distorting the paleomagnetic record in sedimentary rocks are presented: signal averaging and inclination underestimation and ...estimation of the parameters of secular variations (their amplitude, the degree of elongation of the distribution of directions, and the direction of elongation of this distribution) recorded in sedimentary sections.As an example of the practical application of the results obtained on their basis, the prospects of the Honako-2 section, one of the best loess sections in Central Asia, are assessed for the possible discovery of records of geomagnetic excursions in this section. Numerical estimates are obtained for the probability of detecting excursions of different types in the paleomagnetic record of the upper levels of this section.
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