749 research outputs found

    Northern Hemisphere permafrost map based on TTOP modelling for 2000-2016 at 1 km<sup>2 </sup>scale

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    Permafrost is a key element of the cryosphere and an essential climate variable in the Global Climate Observing System. There is no remote-sensing method available to reliably monitor the permafrost thermal state. To estimate permafrost distribution at a hemispheric scale, we employ an equilibrium state model for the temperature at the top of the permafrost (TTOP model) for the 2000–2016 period, driven by remotely-sensed land surface temperatures, down-scaled ERA-Interim climate reanalysis data, tundra wetness classes and landcover map from the ESA Landcover Climate Change Initiative (CCI) project. Subgrid variability of ground temperatures due to snow and landcover variability is represented in the model using subpixel statistics. The results are validated against borehole measurements and reviewed regionally. The accuracy of the modelled mean annual ground temperature (MAGT) at the top of the permafrost is ±2 °C when compared to permafrost borehole data. The modelled permafrost area (MAGT 0) is around 21 × 106 km2 (22% of exposed land area), which is approximately 2 × 106 km2 less than estimated previously. Detailed comparisons at a regional scale show that the model performs well in sparsely vegetated tundra regions and mountains, but is less accurate in densely vegetated boreal spruce and larch forests

    The Period Changes of the Cepheid RT Aurigae

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    Observations of the light curve for the 3.7-day Cepheid RT Aur both before and since 1980 indicate that the variable is undergoing an overall period increase, amounting to +0.082 +-0.012 s/yr, rather than a period decrease, as implied by all observations prior to 1980. Superposed on the star's O-C variations is a sinusoidal trend that cannot be attributed to random fluctuations in pulsation period. Rather, it appears to arise from light travel time effects in a binary system. The derived orbital period for the system is P = 26,429 +-89 days (72.36 +-0.24 years). The inferred orbital parameters from the O-C residuals differ from those indicated by existing radial velocity data. The latter imply the most reasonable results, namely a1 sin i = 9.09 (+-1.81) x 10^8 km and a minimum secondary mass of M2 = 1.15 +-0.25 Msun. Continued monitoring of the brightness and radial velocity changes in the Cepheid are necessary to confirm the long-term trend and to provide data for a proper spectroscopic solution to the orbit.Comment: Accepted for publication in PASP (November 2007

    Challenges in QCD matter physics - The Compressed Baryonic Matter experiment at FAIR

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    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

    Northern Hemisphere permafrost map based on TTOP modelling for 2000–2016 at 1 km2 scale

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    Permafrost is a key element of the cryosphere and an essential climate variable in the Global Climate Observing System. There is no remote-sensing method available to reliably monitor the permafrost thermal state. To estimate permafrost distribution at a hemispheric scale, we employ an equilibrium state model for the temperature at the top of the permafrost (TTOP model) for the 2000–2016 period, driven by remotely- sensed land surface temperatures, down-scaled ERA-Interim climate reanalysis data, tundra wetness classes and landcover map from the ESA Landcover Climate Change Initiative (CCI) project. Subgrid variability of ground temperatures due to snow and landcover variability is represented in the model using subpixel statistics. The results are validated against borehole measurements and reviewed regionally. The accuracy of the modelled mean annual ground temperature (MAGT) at the top of the permafrost is ±2 °C when compared to permafrost borehole data. The modelled permafrost area (MAGT 0) is around 21 × 106 km2 (22% of exposed land area), which is approximately 2 × 106 km2 less than estimated previously. Detailed comparisons at a regional scale show that the model performs well in sparsely vegetated tundra regions and mountains, but is less accurate in densely vegetated boreal spruce and larch forests

    Динамика органной дисфункции и маркеров воспаления у пациентов с септическим шоком при мультимодальной гемокоррекции: мультицентровое, рандомизированное, контролируемое исследование

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    АКТУАЛЬНОСТЬ: Септический шок считается наиболее серьезным осложнением в интенсивной медицине и сопровождается значительной летальностью. Экстракорпоральная гемокоррекция может улучшить результаты лечения пациентов с септическим шоком. ЦЕЛЬ ИССЛЕДОВАНИЯ: оценка влияния гемокоррекции с помощью мультимодального адсорбента «Эфферон ЛПС» на динамику органной дисфункции и маркеры воспаления у пациентов с септическим шоком. МАТЕРИАЛЫ И МЕТОДЫ: Мультицентровое рандомизированное контролируемое исследование проведено в четырех медицинских организациях города Москвы (НИИ СП им. Н.Ф. Склифосовского ДЗМ, ГКБ № 1 им. Н.И. Пирогова ДЗМ, ГКБ им. С.С. Юдина ДЗМ, ГКБ № 68 им. В.П. Демихова ДЗМ) с марта 2021 г. по май 2022 г. В исследование включены 58 пациентов (29 мужчин и 29 женщин) с септическим шоком. Рандомизацию проводили в соотношении 2:1 (гемоперфузия: контроль). Не позднее 24 ч после включения пациента в исследование выполняли процедуры селективной гемоперфузии или использовали стандартную терапию. Гемосорбцию с использованием «Эфферон ЛПС» проводили двукратно, с интервалом 24,5 (23,3–26,0) ч. РЕЗУЛЬТАТЫ: Применение селективного гемосорбента «Эфферон ЛПС» позволило уже через 72 ч снизить тяжесть органной дисфункции у пациентов с септическим шоком с 7 до 3 баллов по шкале SOFA (Sequential Organ Failure Assessment) за счет улучшения гемодинамики, респираторной и почечной функции. В отличие от контрольной группы, в группе «Эфферон ЛПС» уже через 72 ч значимо снижался уровень С-реактивного белка (СРБ) в 1,5 раза, прокальцитонина (ПКТ) — в 2,7 раза, интерлейкина-6 — в 2,3 раза. Тяжесть органной дисфункции значимо коррелировала с уровнем СРБ (r = 0,346) и ПКТ (r = 0,444). Длительность госпитализации выживших пациентов составила 16,1 и 30,1 дня в группе «Эфферон ЛПС» и контрольной группе соответственно (p = 0,032). Потребность в проведении заместительной почечной терапии у выживших к 3-м суткам значимо снижалась с 73,7 до 33,3 % только в группе «Эфферон ЛПС», но не в контрольной группе. ВЫВОДЫ: Применение селективного гемосорбента «Эфферон ЛПС» позволило уменьшить выраженность системного воспаления и значимо снизить тяжесть органной дисфункции у пациентов с септическим шоком за счет улучшения показателей гемодинамики, газообмена и почечной функции

    Long-range angular correlations on the near and away side in p&#8211;Pb collisions at

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    Production of He-4 and (4) in Pb-Pb collisions at root(NN)-N-S=2.76 TeV at the LHC

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    Results on the production of He-4 and (4) nuclei in Pb-Pb collisions at root(NN)-N-S = 2.76 TeV in the rapidity range vertical bar y vertical bar <1, using the ALICE detector, are presented in this paper. The rapidity densities corresponding to 0-10% central events are found to be dN/dy4(He) = (0.8 +/- 0.4 (stat) +/- 0.3 (syst)) x 10(-6) and dN/dy4 = (1.1 +/- 0.4 (stat) +/- 0.2 (syst)) x 10(-6), respectively. This is in agreement with the statistical thermal model expectation assuming the same chemical freeze-out temperature (T-chem = 156 MeV) as for light hadrons. The measured ratio of (4)/He-4 is 1.4 +/- 0.8 (stat) +/- 0.5 (syst). (C) 2018 Published by Elsevier B.V.Peer reviewe

    Azimuthal anisotropy of charged jet production in root s(NN)=2.76 TeV Pb-Pb collisions

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    We present measurements of the azimuthal dependence of charged jet production in central and semi-central root s(NN) = 2.76 TeV Pb-Pb collisions with respect to the second harmonic event plane, quantified as nu(ch)(2) (jet). Jet finding is performed employing the anti-k(T) algorithm with a resolution parameter R = 0.2 using charged tracks from the ALICE tracking system. The contribution of the azimuthal anisotropy of the underlying event is taken into account event-by-event. The remaining (statistical) region-to-region fluctuations are removed on an ensemble basis by unfolding the jet spectra for different event plane orientations independently. Significant non-zero nu(ch)(2) (jet) is observed in semi-central collisions (30-50% centrality) for 20 <p(T)(ch) (jet) <90 GeV/c. The azimuthal dependence of the charged jet production is similar to the dependence observed for jets comprising both charged and neutral fragments, and compatible with measurements of the nu(2) of single charged particles at high p(T). Good agreement between the data and predictions from JEWEL, an event generator simulating parton shower evolution in the presence of a dense QCD medium, is found in semi-central collisions. (C) 2015 CERN for the benefit of the ALICE Collaboration. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).Peer reviewe

    Forward-central two-particle correlations in p-Pb collisions at root s(NN)=5.02 TeV

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    Two-particle angular correlations between trigger particles in the forward pseudorapidity range (2.5 2GeV/c. (C) 2015 CERN for the benefit of the ALICE Collaboration. Published by Elsevier B. V.Peer reviewe

    Event-shape engineering for inclusive spectra and elliptic flow in Pb-Pb collisions at root(NN)-N-S=2.76 TeV

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