174 research outputs found
Asymptotic expansion of the solution of the steady Stokes equation with variable viscosity in a two-dimensional tube structure
The Stokes equation with the varying viscosity is considered in a thin tube
structure, i.e. in a connected union of thin rectangles with heights of order
and with bases of order 1 with smoothened boundary. An
asymptotic expansion of the solution is constructed: it contains some
Poiseuille type flows in the channels (rectangles) with some boundary layers
correctors in the neighborhoods of the bifurcations of the channels. The
estimates for the difference of the exact solution and its asymptotic
approximation are proved.Comment: 22 pages, 20 figure
Results of a search for 2-decay of Xe with high-pressure copper proportional counters in Baksan Neutrino Observatory
The experiment for the 2-decay of Xe search with two
high-pressure copper proportional counters has been held in Baksan neutrino
observatory. The search for the process is based on comparison of spectra
measured with natural and enriched xenon. No evidence has been found for
2(2)- and 2(0)-decay. The decay half lifetime limit
based on data measured during 8000 h is Tyr for
2-mode and Tyr for 0-mode (90%C.L.).Comment: 9 pages, 8 figures; talk at the NANP'05 Conference; submitted to
Phys. At. Nuc
Synthesis and study of the properties of derivatives 4-phenyl-5-(1H-pyrrol-2-yl)-4H-1,2,4-triazole-3-thiols
The successful use of drugs, derivatives of 1,2,4-triazole, creates the conditionsfor the production and investigation of properties of new derivatives of this heterocyclic system.
The aim of this work was synthesis and study of physical and chemical properties of new derivatives of 1,2,4-triazole-3-thiol containing synthon of pyrrole.
The object of the study was a 4-phenyl-5-(pyrrol-2-yl)-1,2,4-triazole-3-ylthio-R-carbothioamides.
To achieve this goal it was necessary to solve following tasks: to conduct the selection of the optimum base structure to determine the most efficient way of chemical modification of the precursor of targeted synthesis, to carry out selection of necessary methods of synthesis, to investigate the physico-chemical properties and to set the structure of the obtained compounds.
The synthesis of target products of the reaction was carried out using as starting material pyrrole, which with using the form non-catalytic form of reaction of the Fridel-Crafts was transformed into 2,2,2-trichloro-1-(pyrrol-2-yl), ethanol. The resulting material in the result of reaction of hydrazinolysis was converted into the pyrrol-2-carbohydrazide. The obtained intermediate product was used in the reaction of nucleophilic joining of phenylisothiocyanate with subsequent intramolecular alkaline heterocyclization. Synthesized thiol was used in the reaction of alkylation.
The structure of the obtained substances are confirmed by using elemental analysis, 1H-NMR-spectroscopy, and their individuality – chromatographic methods of analysis. The resulting substances are an interesting object for further studies, especially biological activity
FEATURES OF HEART RATE REGULATION IN ADOLESCENTS WITH ESSENTIAL HYPERTENSION
Cardiointervalography is an important method of analyzing the regulation of heart rate variability, which allows evaluating the balance of the entire spectrum of humoral-metabolic and vegetative effects, both in condition of physiological rest and in various functional tests. It is noted that in hypertensive patients, in most cases, there is a chronic predominance of ergotrophic metabolic reactions that reflect the system tension in the regulatory mechanisms. The aim of our study was to conduct a comparative analysis of the features of the mechanisms of heart rate regulation in adolescents with confirmed essential hypertension and their healthy age mates. Material and methods. The study involved 50 adolescents (12–16 years of age) – 26 boys and 24 girls with labile essential hypertension (EHT) and stage 1 HT on the background of the standard medical correction of blood pressure (enalapril 0,58 mg/kg per day). Each participant of the study and control group underwent recording of at least 512 cardio cycles in the state of physiological rest in a sitting position, as well as registration of blood pressure. Results and discussion. We have found that for adolescents with EHT a significantly lower (by 15 %) average duration of the heart cycle is typical in combination with a decrease in the variation range, which indicates some rigidity of the heart rate regulatory mechanisms. The relative decrease in the proportion of high-frequency spectrum components in comparison with the low-frequency and very low-frequency ranges in adolescents with hypertension also indicated a tendency to predominance of sympathicotonic effects with the predominant involvement of the structures of the diencephalic region and the brain stem. At the same time blood pressure inversely correlated with the index of the variation range of cardiointervals, reflecting the lower adaptive potential of the heart rate regulation mechanisms. Conclusion. We have found regular changes in the regulation of heart rate in adolescents with hypertension, that can be taken as markers of its progressive development and used by clinicians to develop more personalized approaches to medication treatment
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Experimental study of self-trapping in capillary discharge guided laser wakefield acceleration
Laser wakefield acceleration experiments were carried out using hydrogen-filled capillary discharge waveguides. For a 33 mm long, 300 mu m capillary, parameter regimes with high energy electron beams (up to 1 GeV) and stable 0.5 GeV were found. In the high energy regime, the electron beam peak energy was correlated with the number of trapped electrons. For a 15 mm long, 200 mu m diameter capillary, quasi-monoenergetic e beams up to 300 MeV were observed. By de-tuning discharge delay from optimum guiding performance, self-trapping was found to be stabilized
The CCR4-NOT Complex Physically and Functionally Interacts with TRAMP and the Nuclear Exosome
BACKGROUND: Ccr4-Not is a highly conserved multi-protein complex consisting in yeast of 9 subunits, including Not5 and the major yeast deadenylase Ccr4. It has been connected functionally in the nucleus to transcription by RNA polymerase II and in the cytoplasm to mRNA degradation. However, there has been no evidence so far that this complex is important for RNA degradation in the nucleus. METHODOLOGY/PRINCIPAL FINDINGS: In this work we point to a new role for the Ccr4-Not complex in nuclear RNA metabolism. We determine the importance of the Ccr4-Not complex for the levels of non-coding nuclear RNAs, such as mis-processed and polyadenylated snoRNAs, whose turnover depends upon the nuclear exosome and TRAMP. Consistently, mutation of both the Ccr4-Not complex and the nuclear exosome results in synthetic slow growth phenotypes. We demonstrate physical interactions between the Ccr4-Not complex and the exosome. First, Not5 co-purifies with the exosome. Second, several exosome subunits co-purify with the Ccr4-Not complex. Third, the Ccr4-Not complex is important for the integrity of large exosome-containing complexes. Finally, we reveal a connection between the Ccr4-Not complex and TRAMP through the association of the Mtr4 helicase with the Ccr4-Not complex and the importance of specific subunits of Ccr4-Not for the association of Mtr4 with the nuclear exosome subunit Rrp6. CONCLUSIONS/SIGNIFICANCE: We propose a model in which the Ccr4-Not complex may provide a platform contributing to dynamic interactions between the nuclear exosome and its co-factor TRAMP. Our findings connect for the first time the different players involved in nuclear and cytoplasmic RNA degradation
First Results from the AMoRE-Pilot neutrinoless double beta decay experiment
The Advanced Molybdenum-based Rare process Experiment (AMoRE) aims to search
for neutrinoless double beta decay (0) of Mo with
100 kg of Mo-enriched molybdenum embedded in cryogenic detectors
with a dual heat and light readout. At the current, pilot stage of the AMoRE
project we employ six calcium molybdate crystals with a total mass of 1.9 kg,
produced from Ca-depleted calcium and Mo-enriched molybdenum
(CaMoO). The simultaneous detection of
heat(phonon) and scintillation (photon) signals is realized with high
resolution metallic magnetic calorimeter sensors that operate at milli-Kelvin
temperatures. This stage of the project is carried out in the Yangyang
underground laboratory at a depth of 700 m. We report first results from the
AMoRE-Pilot search with a 111 kgd live exposure of
CaMoO crystals. No evidence for
decay of Mo is found, and a upper limit is set for the
half-life of 0 of Mo of y at 90% C.L.. This limit corresponds to an effective
Majorana neutrino mass limit in the range eV
Challenges in QCD matter physics - The Compressed Baryonic Matter experiment at FAIR
Substantial experimental and theoretical efforts worldwide are devoted to
explore the phase diagram of strongly interacting matter. At LHC and top RHIC
energies, QCD matter is studied at very high temperatures and nearly vanishing
net-baryon densities. There is evidence that a Quark-Gluon-Plasma (QGP) was
created at experiments at RHIC and LHC. The transition from the QGP back to the
hadron gas is found to be a smooth cross over. For larger net-baryon densities
and lower temperatures, it is expected that the QCD phase diagram exhibits a
rich structure, such as a first-order phase transition between hadronic and
partonic matter which terminates in a critical point, or exotic phases like
quarkyonic matter. The discovery of these landmarks would be a breakthrough in
our understanding of the strong interaction and is therefore in the focus of
various high-energy heavy-ion research programs. The Compressed Baryonic Matter
(CBM) experiment at FAIR will play a unique role in the exploration of the QCD
phase diagram in the region of high net-baryon densities, because it is
designed to run at unprecedented interaction rates. High-rate operation is the
key prerequisite for high-precision measurements of multi-differential
observables and of rare diagnostic probes which are sensitive to the dense
phase of the nuclear fireball. The goal of the CBM experiment at SIS100
(sqrt(s_NN) = 2.7 - 4.9 GeV) is to discover fundamental properties of QCD
matter: the phase structure at large baryon-chemical potentials (mu_B > 500
MeV), effects of chiral symmetry, and the equation-of-state at high density as
it is expected to occur in the core of neutron stars. In this article, we
review the motivation for and the physics programme of CBM, including
activities before the start of data taking in 2022, in the context of the
worldwide efforts to explore high-density QCD matter.Comment: 15 pages, 11 figures. Published in European Physical Journal
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