Investigation of the angular distribution and energy spectrum of fast ions produced during irradiation of targets by short laser pulses in the SOKOL-P facility

Results are presented from experimental investigations of the angular distributions and energy spectra of fast ions produced in deuterium polyethylene targets under irradiation by picosecond laser pulses with intensities of up to 2 × 10¹⁸ W/cm² in the SOKOL-P facility. The parameters of ion fluxes were measured by time-of-flight spectrometers based on semiconductor detectors.     

Synthesis and properties of DNA duplexes containing hydrocarbon bridges instead of a nucleoside residue

DNA duplexes 14 bp long containing an EcoRII and MvaI restriction site in which a nucleoside is substituted by 1,3-diaminopropane or 1,3-propanediol residue have been chemically synthesized. Diaminopropane bridge was introduced by the chemical ligation, whereas the oligonucleotide containing propanediol was prepared by automatic solid phase phosphoroamidite method on "Victoria-4M" synthesizer. As CD and UV spectra show, the modification destabilises the duplex by 18-20 degrees C without essential distortion of the double helix, except for increase of the conformational mobility in the modified site.     

The role of a template sugar-phosphate backbone in the ribosomal decoding mechanism. Comparative study of poly(U) and poly(dT) template activity

To study the role of a template sugar-phosphate backbone in the ribosomal decoding process, poly(U), poly(dT) and poly(dU)-directed cell-free amino acid incorporation was investigated under the influence of neomycin and high concentrations of Mg2+. The specificity of a factor-dependent translation system of Escherichia coli was shown to change according to the principle: "either ribo- or deoxyribopolynucleotide messenger". Poly(dT) is shown to be effectively translated in the absence of elongation factors, both at low (2 degrees C) and high (37 degrees C) temperature. Neomycin inhibits factor-free poly(dT) translation. Little or no poly(U) translation is observed in this system. A chromatographic analysis of the oligophenylalanine residues synthesized seems to show that translocation is the main step responsible for ribosome specificity to the ribo- or deoxyribopolynucleotide template in both factor-dependent and factor-free translation systems.     

Self-organization of day cycle and hierarchical associative memory in “live” neural network

The live neural network model is proposed on the basis of live neuron model and optimal learning rule. By means of numerical simulation the initial stages of neural network self-organization have been shown: (1) the formation of two activity forms, which are identified with sleep and awaking, and (2) the self-organization of hierarchical associative memory when feeding a receptor excitation to the neural network. The energetic profit of self-organization is demonstrated. The formation of neural ensembles, playing the role of generalized neurons, is obtained.     

Detection of soluble antigens of blood group ABH using immunoenzyme analysis

The use of the indirect ELISA techniques did not ensure the sharp differentiation of the antigens of the blood groups A and B on the polystyrene sorbent by means of heteroimmune sera, though such differentiation could be achieved by means of monoclonal antibodies. The test system known as "the lectin-antibody sandwich" was found to have the optimum sensitivity and specificity permitting the detection of soluble ABH antigens. This variant of ELISA permitted the detection of blood group A antigen both in native biological materials and in traces of blood and saliva, thus making it possible to carry out its quantitative determination.     

Inhibition in the fish olfactory bulb

Inhibition in the olfactory bulb of the carp was studied by recording potentials from secondary neurons intracellularly. Three types of inhibition — trace, early, and late — can arise in neurons of the olfactory bulb. Trace inhibition corresponds to hyperpolarization about 20 msec in duration, which is closely connected with the spike, but it is not after-hyperpolarization but an IPSP. Early and late inhibition correspond to IPSPs of different parameters. The first has a latency of 0–50 msec (relative to the spike) and a duration of 60–400 msec; the corresponding values for the second are 100–400 msec and 0.5–3 sec. The possible mechanisms of these types of inhibition are discussed.M. V. Lomonosov Moscow State University. Translated from Neirofiziologiya, Vol. 3, No. 6, pp. 650–656, November–December, 1971.     

Characteristics of electrical activity of olfactory bulb neurons of fish

It was shown by intracellular recording of the activity of olfactory bulb neurons of the carp that their dendrites are excited both by synaptic activation and by direct stimulation with an electric current. The dendrites generate an action potential and probably conduct it for some distance toward the soma. The neurons can be divided into two groups: one responds to ortho- and antidromic stimuli with one, rarely with two peaks, the other responds with a rhythmical discharge. The presence of early and late IPSP is characteristic of neurons of both groups. Rhythmical variations in potential with a frequency of 26–33/sec, so-called oscillations, are recorded; they may be excitatory (in secondary neurons they correspond to EPSP) or inhibitory (they correspond to IPSP). Possible mechanisms of the excitatory oscillations and the rhythmical discharge in olfactory bulb neurons of the carp are discussed.M. V. Lomonosov Moscow State University. Translated from Neirofiziologiya, Vol.3, No.5, pp. 505–511, September–October, 1971.