75 research outputs found
New features of the phase transition to superconducting state in thin films
The Halperin-Lubensky-Ma (HLM) effect of a fluctuation-induced change of the
order of phase transition in thin films of type I superconductors with
relatively small Ginzburg-Landau number is considered. Numerical data
for the free energy, the order parameter jump, the latent heat, and the
specific heat of W, Al and In are presented to reveal the influence of film
thickness and material parameters on the properties of the phase transition. We
demonstrate for the first time that in contrast to the usual notion the HLM
effect occurs in the most distinct way in superconducting films with high
critical magnetic field rather than in materials with small .
The possibility for an experimental observation of the fluctuation change of
the order of superconducting phase transition in superconducting films is
discussed.Comment: 11 pages, MikTexTeX, 3 fig, 2 Tables, corrected some typos, Submitted
J.Phys:Cond Ma
Effective spatial dimension of extremal non-dilatonic black p-branes and the description of entropy on the world volume
By investigating the critical behavior appearing at the extremal limit of the
non-dilatonic, black p-branes in (d+p) dimensions, we find that some critical
exponents related to the critical point obey the scaling laws. From the scaling
laws we obtain that the effective spatial dimension of the non-dilatonic black
holes and black strings is one, and is p for the non-dilatonic black p-branes.
For the dilatonic black holes and black p-branes, the effective dimension will
depend on the parameters in theories. Thus, we give an interpretation why the
Bekenstein-Hawking entropy may be given a simple world volume interpretation
only for the non-dilatonic black p-branes.Comment: 4 pages, RevTex, no figures, to appear in Phys. Rev. Let
Critical behavior in 2+1 dimensional black holes
The critical behavior and phase transition in the 2+1 dimensional Ba\~nados,
Teitelboim, and Zanelli (BTZ) black holes are discussed. By calculating the
equilibrium thermodynamic fluctuations in the microcanonical ensemble,
canonical ensemble, and grand canonical ensemble, respectively, we find that
the extremal spinning BTZ black hole is a critical point, some critical
exponents satisfy the scaling laws of the ``first kind'', and the scaling laws
related to the correlation length suggest that the effective spatial dimension
of extremal black holes is one, which is in agreement with the argument that
the extremal black holes are the Bogomol'nyi saturated string states. In
addition, we find that the massless BTZ black hole is a critical point of
spinless BTZ black holes.Comment: RevTex, 9 pages, nofigur
Critical Properties of Condensation of Field-Induced Triplet Quasiparticles
A review on the field-induced magnetic ordering is given, together with some
results of a quantum Monte Carlo simulation focused on the critical behevior
near the quantum critical point.Comment: Proceedings of SPQS, Sendai, 200
Neuroactive steroids in depression and anxiety disorders: Clinical studies
Certain neuroactive steroids modulate ligand-gated ion channels via non-genomic mechanisms. Especially 3 alpha-reduced pregnane steroids are potent positive allosteric modulators of the gamma-aminobutyric acid type A (GABA(A)) receptor. During major depression, there is a disequilibrium of 3 alpha-reduced neuroactive steroids, which is corrected by clinically effective pharmacological treatment. To investigate whether these alterations are a general principle of successful antidepressant treatment, we studied the impact of nonpharmacological treatment options on neuroactive steroid concentrations during major depression. Neither partial sleep deprivation, transcranial magnetic stimulation, nor electroconvulsive therapy affected neuroactive steroid levels irrespectively of the response to these treatments. These studies suggest that the changes in neuroactive steroid concentrations observed after antidepressant pharmacotherapy more likely reflect distinct pharmacological properties of antidepressants rather than the clinical response. In patients with panic disorder, changes in neuroactive steroid composition have been observed opposite to those seen in depression. However, during experimentally induced panic induction either with cholecystokinine-tetrapeptide or sodium lactate, there was a pronounced decline in the concentrations of 3 alpha-reduced neuroactive steroids in patients with panic disorder, which might result in a decreased GABAergic tone. In contrast, no changes in neuroactive steroid concentrations could be observed in healthy controls with the exception of 3 alpha,5 alpha-tetrahydrodeoxycorticosterone. The modulation of GABA(A) receptors by neuroactive steroids might contribute to the pathophysiology of depression and anxiety disorders and might offer new targets for the development of novel anxiolytic compounds. Copyright (c) 2006 S. Karger AG, Basel
Television pictures of Phobos: first results
In February-March 1989, 37 television images of the Martian satellite Phobos were obtained by the Phobos 2 spacecraft from distances of 200-1100 km. These images provide an important supplement to the TV data from the American Mariner 9 and Viking spacecraft in coverage of t4e surface of Phobos and in resolution in certain regions, in spectral range, and in range of phase angles. They make it possible to refine the figure and topographic and geological maps of the surface of Phobos, its spectral and angular reflective characteristics,
the surface composition and texture, and characteristics of the orbital and librational motion
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The recovery of European freshwater biodiversity has come to a halt
Owing to a long history of anthropogenic pressures, freshwater ecosystems are among the most vulnerable to biodiversity loss. Mitigation measures, including wastewater treatment and hydromorphological restoration, have aimed to improve environmental quality and foster the recovery of freshwater biodiversity. Here, using 1,816 time series of freshwater invertebrate communities collected across 22 European countries between 1968 and 2020, we quantified temporal trends in taxonomic and functional diversity and their responses to environmental pressures and gradients. We observed overall increases in taxon richness (0.73% per year), functional richness (2.4% per year) and abundance (1.17% per year). However, these increases primarily occurred before the 2010s, and have since plateaued. Freshwater communities downstream of dams, urban areas and cropland were less likely to experience recovery. Communities at sites with faster rates of warming had fewer gains in taxon richness, functional richness and abundance. Although biodiversity gains in the 1990s and 2000s probably reflect the effectiveness of water-quality improvements and restoration projects, the decelerating trajectory in the 2010s suggests that the current measures offer diminishing returns. Given new and persistent pressures on freshwater ecosystems, including emerging pollutants, climate change and the spread of invasive species, we call for additional mitigation to revive the recovery of freshwater biodiversity
Time series of freshwater macroinvertebrate abundances and site characteristics of European streams and rivers
Freshwater macroinvertebrates are a diverse group and play key ecological roles, including accelerating nutrient cycling, filtering water, controlling primary producers, and providing food for predators. Their differences in tolerances and short generation times manifest in rapid community responses to change. Macroinvertebrate community composition is an indicator of water quality. In Europe, efforts to improve water quality following environmental legislation, primarily starting in the 1980s, may have driven a recovery of macroinvertebrate communities. Towards understanding temporal and spatial variation of these organisms, we compiled the TREAM dataset (Time seRies of European freshwAter Macroinvertebrates), consisting of macroinvertebrate community time series from 1,816 river and stream sites (mean length of 19.2 years and 14.9 sampling years) of 22 European countries sampled between 1968 and 2020. In total, the data include >93 million sampled individuals of 2,648 taxa from 959 genera and 212 families. These data can be used to test questions ranging from identifying drivers of the population dynamics of specific taxa to assessing the success of legislative and management restoration efforts.Nathalie Kaffenberger aided in initial data compilation. Funding for authors, data collection and processing was provided by the EU Horizon 2020 project eLTER PLUS (grant agreement no. 871128), German Federal Ministry of Education and Research (BMBF; 033W034A), German Research Foundation (DFG FZT 118, 202548816), the Collaborative Research Centre 1439 RESIST (DFG—SFB 1439/1 2021 –426547801), Czech Republic project no. GA23-05268S, the Leibniz Competition (J45/2018, P74/2018), the Spanish Ministerio de Economía, Industria y Competitividad - Agencia Estatal de Investigación and the European Regional Development Fund (MECODISPER project CTM 2017-89295-P), Ramón y Cajal contracts and the project funded by the Spanish Ministry of Science and Innovation (RYC2019-027446-I, RYC2020-029829-I, PID2020-115830GB-100), the Danish Environment Agency, the Norwegian Environment Agency, SOMINCOR – Lundin mining & FCT - Fundação para a Ciência e Tecnologia, Portugal, the Swedish University of Agricultural Sciences, the Swiss National Science Foundation (Grant PP00P3_179089), the EU LIFE programme (DIVAQUA project - LIFE18 NAT/ES/000121), and the UK Natural Environment Research Council (GLiTRS project -NE/V006886/1 and NE/R016429/1 as part of the UK-SCAPE programme), the Autonomous Province of Bolzano (Italy), Estonian Research Council (grant No PRG1266), Estonian national program ‘Humanitarian and natural science collections’. The Environment Agency of England, the Scottish Environmental Protection Agency and Natural Resources Wales provided publicly available data. The collection of data from the Rhône River in France was greatly aided by Marie-Claude Roger (INRAE Lyon), Jean-Claude Berger (INRAE AIX), and Pâquerette Dessaix (ARALEP). We are also grateful to the French Regional Environment Directorates (DREALs) for their collaboration in harmonising the long-term data series from the other French rivers. We thank the AWEL from the Canton of Zurich for providing access to macroinvertebrate data from the AWEL monitoring scheme. We acknowledge the Flanders Environment Agency, the Rhineland-Palatinate State Office for the Environment and the Bulgarian Executive Environment Agency for providing data. This manuscript is a contribution of the Alliance for Freshwater Life (www.allianceforfreshwaterlife.org). Any views expressed within this paper are those of the authors and do not necessarily represent the views of their respective employer organisations.Peer reviewe
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