4,502 research outputs found

    Integrated chemo- and biostratigraphic calibration of early animal evolution: Neoproterozoic-early Cambrian of southwest Mongolia

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    Five overlapping sections from the thick Neoproterozoic to early Cambrian sediments of western Mongolia were analysed to yield a remarkable carbon-isotope, strontium-isotope and small shellyfossil (SSF) record. Chemostratigraphy suggests that barren limestones of sequences 3 and 4, which lie above the two Maikhan Uul diamictites, are post-Sturtian but pre-Varangerian in age. Limestones and dolomites of sequence 5, with Boxonia grumulosa, have geochemical signatures consistent with a post-Varangerian (Ediacarian) age. A major negative Ξ΄13C anomaly (feature β€˜W') in sequence 6 lies a shortdistance above an Anabarites trisulcatus Zone SSF asemblage with hexactinellid sponges, of probable late Ediacarian age. Anomaly β€˜W' provides an anchor point for cross-correlation charts of carbon isotopes and small shelly fossils. Trace fossil assemblages with a distinctly Cambrian character first appear in sequence 8(Purella Zone), at the level of carbon isotopic feature β€˜B', provisionally correlated with the upper part of cycle Z in Siberia. A paradox is found from sequence 10 to 12 in Mongolia: Tommotian-type SSFs continue to appear, accompanied by Nemakit-Daldynian/Tommotian-type 87Sr/86Sr ratios but by increasingly heavyΞ΄13C values that cannot be matched in the Tommotian of eastern Siberia. The steady rate of generic diversification in Mongolia also contrasts markedly with the Tommotian β€˜diversity explosion' in eastern Siberia, which occurs just above a major karstic emergence surface. One explanation is that sequences 10 to 12 in Mongolia preserve a pre-Tommotian portion of the fossil record that was missing or removed in easternSiberia. The Mongolian sections certainly deserve an important place in tracing the true course and timing of the β€˜Cambrian radiation

    Π Π΅Π³Π΅Π½Π΅Ρ€Π°Ρ‚ΠΈΠ²Π½Ρ‹ΠΉ ΡƒΡΠΈΠ»ΠΈΡ‚Π΅Π»ΡŒ Ρ‡ΠΈΡ€ΠΏΠΈΡ€ΠΎΠ²Π°Π½Π½Ρ‹Ρ… ΠΈΠΌΠΏΡƒΠ»ΡŒΡΠΎΠ² Π½Π° кристаллС Yb3+:LuAlO3 с усилСниСм ΠΎΡ‚Π΄Π΅Π»ΡŒΠ½Ρ‹Ρ… ΡΠΏΠ΅ΠΊΡ‚Ρ€Π°Π»ΡŒΠ½Ρ‹Ρ… ΠΊΠΎΠΌΠΏΠΎΠ½Π΅Π½Ρ‚ для ΠΏΡ€ΠΈΠΌΠ΅Π½Π΅Π½ΠΈΠΉ Π² Ρ‚Π΅Ρ€Π°Π³Π΅Ρ€Ρ†ΠΎΠ²ΠΎΠΉ области спСктра

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    Compact diode-pumped chirped pulse regenerative amplifier systems with pulse repetition rate of hundreds kilohertz based on Yb3+-doped crystals are of practical importance for wide range of applications such as materials processing, medicine, scientific research, etc. The aim of this work was to study the Yb3+:LuAlO3 crystal based dual wavelength chirped pulse regenerative amplifier. Perovskite-like aluminate crystals have unique spectroscopic properties that allowed to use amplifier active element gain spectrum as an amplitude filter for amplified pulse spectrum and even obtained dual wavelength amplification without any additional components. In our work a simple way to obtain dual-wavelength operation of chirped pulse regenerative amplifier by using the active medium gain spectrum as an amplitude filter for the formation of the amplified pulses spectrum demonstrated for the first time to our knowledge. Maximum output power of 5.4 W of chirped pulses (3.8 W after compression) and optical-to-optical efficiency of 22.5 % have been obtained for Yb:LuAP E//b-polarization at 200 kHz repetition rate. Compressed amplified pulse duration was about 708 fs while separate spectral components durations were 643 fs and 536 fs at 1018.3 nm and 1041.1 nm central wavelengths, respectively. Performed investigations show high potential of Yb3+:LuAP crystals as active elements of compact diode pumped chirped pulse regenerative amplifiers

    Высокомощный Π»Π°Π·Π΅Ρ€ Π½Π° кристаллС Yb3+:YAlO3, Ρ€Π°Π±ΠΎΡ‚Π°ΡŽΡ‰ΠΈΠΉ Π² Ρ€Π΅ΠΆΠΈΠΌΠ΅ синхронизации ΠΌΠΎΠ΄ Π½Π° основС ΠΏΠΎΠ»ΡƒΠΏΡ€ΠΎΠ²ΠΎΠ΄Π½ΠΈΠΊΠΎΠ²Ρ‹Ρ… Π·Π΅Ρ€ΠΊΠ°Π» с Π½Π°ΡΡ‹Ρ‰Π°ΡŽΡ‰ΠΈΠΌΡΡ ΠΏΠΎΠ³Π»ΠΎΡ‚ΠΈΡ‚Π΅Π»Π΅ΠΌ

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    Yttrium aluminium perovskite YAlO3 (YAP) crystal, doped with rare-earth ions, has been extensively studied as a diode-pumped laser host material. The wide interest to rare-earth ions doped YAP crystals is explained by its good thermal and mechanical properties, high natural birefringence, widely used Czochralski growth method. The aim of this work was to study the Yb3+:YAlO3 crystal as an active medium for high power mode-locked laser. Yb3+-doped perovskite-like aluminate crystals have unique spectroscopic and thermooptical properties that allowed using these crystals as an active medium of high power continuous wave (CW) and modelocked (ML) bulk lasers with diode pumping. In our work spectroscopic properties of Yb:YAP crystal and laser characteristics in CW and ML regimes are investigated. Maximum output power of 4 W with optical-to-optical efficiency of 16.3 % and 140 fs pulse duration have been obtained for Yb:YAP E //c-polarization with 10 % output coupler transmittance. Tunability range as wide as 67 nm confirms high promise of using Yb:YAP crystal for lasers working in wide spectral range

    Signal Processing

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    Contains reports on three research projects.Joint Services Electronics Programs (U. S. Army, U. S. Navy, and U. S. Air Force) under Contract DA 28-043-AMC-02536(E

    Probing invisible vector meson decay mode with hadronic beam in the NA64 experiment at SPS/CERN

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    We test a novel idea of using a Ο€βˆ’\pi^- beam in the fixed-target experiments to search for New Physics in the events with missing energy. Bounds for invisible vector ρ\rho meson decay were derived, analyzed, and compared with the current limits on searching Dark Matter in the accelerator based experiments. We demonstrate that the new approach can be effective tool to probe sub-GeV Dark Matter parameter space.Comment: 8 pages,, 5 figures and 1 Tabl

    Second virial coefficients of light nuclear clusters and their chemical freeze-out in nuclear collisions

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    Here we develop a new strategy to analyze the chemical freeze-out of light (anti)nuclei produced in high energy collisions of heavy atomic nuclei within an advanced version of the hadron resonance gas model. It is based on two different, but complementary approaches to model the hard-core repulsion between the light nuclei and hadrons. The first approach is based on an approximate treatment of the equivalent hard-core radius of a roomy nuclear cluster and pions, while the second approach is rigorously derived here using a self-consistent treatment of classical excluded volumes of light (anti)nuclei and hadrons. By construction, in a hadronic medium dominated by pions, both approaches should give the same results. Employing this strategy to the analysis of hadronic and light (anti)nuclei multiplicities measured by ALICE at sNN=2.76\sqrt{s_{NN}} =2.76 TeV and by STAR at sNN=200\sqrt{s_{NN}} =200 GeV, we got rid of the existing ambiguity in the description of light (anti)nuclei data and determined the chemical freeze-out parameters of nuclei with high accuracy and confidence. At ALICE energy the nuclei are frozen prior to the hadrons at the temperature T=175.1βˆ’3.9+2.3T = 175.1^{+2.3}_{-3.9} MeV, while at STAR energy there is a single freeze-out of hadrons and nuclei at the temperature T=167.2Β±3.9T = 167.2 \pm 3.9 MeV. We argue that the found chemical freeze-out volumes of nuclei can be considered as the volumes of quark-gluon bags that produce the nuclei at the moment of hadronization.Comment: 15 pages, 4 figures, 3 table

    Study of Antibiotic Resistance of the Oropharyngeal Hemolytic Microflora in Preschool Children

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    It is impossible to imagine modern medical practice without antibiotic therapy. However, the rapid development of the pharmaceutical industry expands free access of the population to antibacterial drugs. At the same time, the illiteracy of people with respect to the principles of rational antibiotic therapy also increases. The problem of microbial resistance to antibacterial drugs remains relevant to this day. Special attention should be paid to rational antibiotic therapy applied to children.The purpose of this work was to study the resistance of hemolytic microorganisms, which are often the cause of upper respiratory infection in preschool children, to the main antibacterial drugs used in pediatric practice. The results of this scientific research can be advisory and useful to pediatricians and other specialists whose professional activities are related to children’s health. Keywords: hemolytic active microorganisms, bacterial carriage, antibiotic resistance, children’s healt

    ЛСгочная рСабилитация ΠΏΠ°Ρ†ΠΈΠ΅Π½Ρ‚ΠΎΠ², ΠΏΠ΅Ρ€Π΅Π½Π΅ΡΡˆΠΈΡ… ΠΊΠΎΡ€ΠΎΠ½Π°Π²ΠΈΡ€ΡƒΡΠ½ΡƒΡŽ ΠΈΠ½Ρ„Π΅ΠΊΡ†ΠΈΡŽ COVID-19 (клиничСскиС ΠΏΡ€ΠΈΠΌΠ΅Ρ€Ρ‹)

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    At the end of 2019, an outbreak of a new coronavirus infection was identified in the People’s Republic of China centerd in the city of Wuhan. The official name COVID-19 (COronaVIrus Disease 2019) was assigned to the infection caused by the novel coronavirus by the World Health Organization on February 11, 2020. The International Committee on Taxonomy of Viruses assigned the name to the causative agent of the infection – SARS-CoV-2 on February 11, 2020. The bilateral pneumonia is currently known to be the most common clinical manifestation of the variant of coronavirus infection. The development of acute respiratory distress syndrome was found in 3 – 4% of patients. As a result of pneumonia, patients develop ventilation and perfusion disorders, weakness of skeletal muscles. To recover patients after viral pneumonia, methods of pulmonary rehabilitation should be applied. This article represents the methods of pulmonary rehabilitation aimed to improve the blood circulation in the lungs, the ventilation-perfusion ratios, and to the restoration of the skeletal muscles.Π’ ΠΊΠΎΠ½Ρ†Π΅ 2019 Π³ΠΎΠ΄Π° Π² ΠšΠΈΡ‚Π°ΠΉΡΠΊΠΎΠΉ Народной РСспубликС ΠΏΡ€ΠΎΠΈΠ·ΠΎΡˆΠ»Π° Π²ΡΠΏΡ‹ΡˆΠΊΠ° Π½ΠΎΠ²ΠΎΠΉ коронавирусной ΠΈΠ½Ρ„Π΅ΠΊΡ†ΠΈΠΈ с эпицСнтром Π² Π³ΠΎΡ€ΠΎΠ΄Π΅ Π£Ρ…Π°Π½ΡŒ. ВсСмирная организация здравоохранСния 11.02.20 присвоила ΠΎΡ„ΠΈΡ†ΠΈΠ°Π»ΡŒΠ½ΠΎΠ΅ Π½Π°Π·Π²Π°Π½ΠΈΠ΅ ΠΈΠ½Ρ„Π΅ΠΊΡ†ΠΈΠΈ, Π²Ρ‹Π·Π²Π°Π½Π½ΠΎΠΉ Π½ΠΎΠ²Ρ‹ΠΌ коронавирусом, COVID-19 (CОronaVIrus DiseaseΒ­2019). ΠœΠ΅ΠΆΠ΄ΡƒΠ½Π°Ρ€ΠΎΠ΄Π½Ρ‹ΠΉ ΠΊΠΎΠΌΠΈΡ‚Π΅Ρ‚ ΠΏΠΎ таксономии вирусов 11.02.20 присвоил Π½Π°Π·Π²Π°Π½ΠΈΠ΅ Π²ΠΎΠ·Π±ΡƒΠ΄ΠΈΡ‚Π΅Π»ΡŽ ΠΈΠ½Ρ„Π΅ΠΊΡ†ΠΈΠΈ SARS-CoV-2. Π’ настоящСС врСмя извСстно, Ρ‡Ρ‚ΠΎ Π½Π°ΠΈΠ±ΠΎΠ»Π΅Π΅ распространСнным клиничСским проявлСниСм Π²Π°Ρ€ΠΈΠ°Π½Ρ‚Π° коронавирусной ΠΈΠ½Ρ„Π΅ΠΊΡ†ΠΈΠΈ являСтся двусторонняя пнСвмония, Ρƒ 3–4 % ΠΏΠ°Ρ†ΠΈΠ΅Π½Ρ‚ΠΎΠ² зарСгистрировано Ρ€Π°Π·Π²ΠΈΡ‚ΠΈΠ΅ острого рСспираторного дистрСсссиндрома. ΠŸΡ€ΠΈ ΠΏΠ½Π΅Π²ΠΌΠΎΠ½ΠΈΠΈ Ρƒ ΠΏΠ°Ρ†ΠΈΠ΅Π½Ρ‚ΠΎΠ² Ρ€Π°Π·Π²ΠΈΠ²Π°ΡŽΡ‚ΡΡ вСнтиляционно-ΠΏΠ΅Ρ€Ρ„ΡƒΠ·ΠΈΠΎΠ½Π½Ρ‹Π΅ Π½Π°Ρ€ΡƒΡˆΠ΅Π½ΠΈΡ, ΡΠ»Π°Π±ΠΎΡΡ‚ΡŒ скСлСтной мускулатуры. Для восстановлСния ΠΏΠ°Ρ†ΠΈΠ΅Π½Ρ‚ΠΎΠ² послС вирусной ΠΏΠ½Π΅Π²ΠΌΠΎΠ½ΠΈΠΈ Π½Π΅ΠΎΠ±Ρ…ΠΎΠ΄ΠΈΠΌΠ° лСгочная рСабилитация. Π’ Π΄Π°Π½Π½ΠΎΠΉ ΡΡ‚Π°Ρ‚ΡŒΠ΅ ΠΏΡ€ΠΈΠ²Π΅Π΄Π΅Π½Ρ‹ ΠΌΠ΅Ρ‚ΠΎΠ΄Ρ‹ Π»Π΅Π³ΠΎΡ‡Π½ΠΎΠΉ Ρ€Π΅Π°Π±ΠΈΠ»ΠΈΡ‚Π°Ρ†ΠΈΠΈ, Π½Π°ΠΏΡ€Π°Π²Π»Π΅Π½Π½Ρ‹Π΅ Π½Π° ΡƒΠ»ΡƒΡ‡ΡˆΠ΅Π½ΠΈΠ΅ кровообращСния Π² Π»Π΅Π³ΠΊΠΈΡ…, вСнтиляционно-ΠΏΠ΅Ρ€Ρ„ΡƒΠ·ΠΈΠΎΠ½Π½Ρ‹Ρ… ΠΎΡ‚Π½ΠΎΡˆΠ΅Π½ΠΈΠΉ, восстановлСниС Ρ€Π°Π±ΠΎΡ‚Ρ‹ скСлСтной мускулатуры
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