5,964 research outputs found
A comment on the relation between diffraction and entropy
Diffraction methods are used to detect atomic order in solids. While uniquely
ergodic systems with pure point diffraction have zero entropy, the relation
between diffraction and entropy is not as straightforward in general. In
particular, there exist families of homometric systems, which are systems
sharing the same diffraction, with varying entropy. We summarise the present
state of understanding by several characteristic examples.Comment: 7 page
Forming peculiarities and manifestation of tectonic faults in soft rocks
Features of distribution of tectonic structures in soft rocks confirm the presence of horizontal tectonic forces in the formation of faults and are based on the manifestation of their morphological features. Linear dependences of the amplitude on the length of tectonic dislocation in the area of wedging were obtained as a result of mathematical processing of the experimental data. Actual position of the crossing lines of fault plane with the seam were considered while studying the distribution of co-fault fracturing. Analysis of the data confirms that the distribution of faulting has an undulating character. Analysis of observations showed that the deviation of the crossing line of fault plane with the seam from the middle line is subject to the normal law of random variable distribution. Thus, the studies and the obtained results allow planning mining operations assessing the utility while developing fault areas
Perpendicular transport and magnetization processes in magnetic multilayers with strongly and weakly coupled magnetic layers
Within the framework of a two-band tight-binding model, we have performed
calculations of giant magnetoresistance, exchange coupling and thermoelectric
power (TEP) for a system consisting of three magnetic layers separated by two
non-magnetic spacers with the first two magnetic layers strongly
antiferromagnetically exchange-coupled. We have shown how does the GMR relate
with the corresponding regions of magnetic structure phase diagrams and
computed some relevant hysteresis loops, too. The GMR may take negative values
for specific layers thicknesses, and the TEP reveals quite pronounced
oscillations around a negative bias.Comment: 16 pages, 10 figures, submited to Journal of Magnetism and Magnetic
Material
Rotationally adiabatic pair interactions of para- and ortho-hydrogen with the halogen molecules F2, Cl2, and Br2
The present work is concerned with the weak interactions between hydrogen and
halogen molecules, i.e., the interactions of pairs H2–X2 with X = F, Cl, Br,
which are dominated by dispersion and quadrupole-quadrupole forces. The global
minimum of the four-dimensional (4D) coupled cluster with singles and doubles
and perturbative triples (CCSD(T)) pair potentials is always a T shaped
structure where H2 acts as the hat of the T, with well depths (D e ) of 1.3,
2.4, and 3.1 kJ/mol for F2, Cl2, and Br2, respectively. MP2/AVQZ results, in
reasonable agreement with CCSD(T) results extrapolated to the basis set limit,
are used for detailed scans of the potentials. Due to the large difference in
the rotational constants of the monomers, in the adiabatic approximation, one
can solve the rotational Schrödinger equation for H2 in the potential of the
X2 molecule. This yields effective two-dimensional rotationally adiabatic
potential energy surfaces where pH2 and oH2 are point-like particles. These
potentials for the H2–X2 complexes have global and local minima for effective
linear and T-shaped complexes, respectively, which are separated by 0.4-1.0
kJ/mol, where oH2 binds stronger than pH2 to X2, due to higher alignment to
minima structures of the 4D-pair potential. Further, we provide fits of an
analytical function to the rotationally adiabatic potentials
Polyunsaturated Fatty Acids and Risk of Ischemic Stroke
Ischemic stroke is a major cause of death and morbidity worldwide. It has been suggested that polyunsaturated fatty acids (PUFAs) may be associated with a lower risk ischemic stroke, but this has been far less studied than their role for coronary heart disease. In this paper, we summarize the main findings from previous follow-up studies investigating associations between intake or biomarkers of the major PUFAs including alpha-linolenic acid (ALA), marine n-3 PUFAs and linoleic acid (LA) and the development of ischemic stroke. Several follow-up studies have suggested that marine n-3 PUFAs may be associated with a lower risk of ischemic stroke although results have not been consistent and limited knowledge exist on the individual marine n-3 PUFAs and ischemic stroke and its subtypes. The role of ALA is less clear, but most studies have not supported that ALA is appreciably associated with ischemic stroke risk. Some studies have supported that LA might be associated with a lower risk of total ischemic stroke, while limited evidence exist on PUFAs and ischemic stroke subtypes. The associations may depend on the macronutrients that PUFAs replace and this substitution aspect together with focus on dietary patterns represent interesting areas for future research
Dual Magnetic Separator for TRIP
The TRIP facility, under construction at KVI, requires the production
and separation of short-lived and rare isotopes. Direct reactions,
fragmentation and fusion-evaporation reactions in normal and inverse kinematics
are foreseen to produce nuclides of interest with a variety of heavy-ion beams
from the superconducting cyclotron AGOR. For this purpose, we have designed,
constructed and commissioned a versatile magnetic separator that allows
efficient injection into an ion catcher, i.e., gas-filled stopper/cooler or
thermal ionizer, from which a low energy radioactive beam will be extracted.
The separator performance was tested with the production and clean separation
of Na ions, where a beam purity of 99.5% could be achieved. For
fusion-evaporation products, some of the features of its operation as a
gas-filled recoil separator were tested.Comment: accepted by Nucl.Instr. Meth., final versio
Cellular Adhesion Molecules in Healthy Subjects: Short Term Variations and Relations to Flow Mediated Dilation
The objective was primarily to describe short term intra-individual variation in serum levels of soluble adhesion molecules (sCAMs: E-selectin, P-selectin, intercellular adhesion molecule-1(sICAM-1) and vascular cellular adhesion molecule-1(sVCAM-1)) in healthy subjects. Secondly, sCAMs were correlated to brachial artery flow mediated vasodilation (FMD)
Transactional Sex: Supply and Demand Among European Men Who have Sex with Men (MSM) in the Context of Local Laws.
Objectives: Transactional sex (TS) is generally defined as the trading of sex for material goods. Cast within the broader context of prostitution laws, we examined variations in the sociodemographic profile of men who have sex with men engaging in TS by payment direction (buying/selling). Methods: The data were collected as part of the 38-country European Men who have sex with men Internet Survey project, conducted in 2010. Results: About 12% of respondents reported engaging in TS in the past year. TS was associated with laws, age, education, employment, and residence. Conclusions: The striking sociodemographic differences in TS by payment direction suggest a power differential and a leading role of socioeconomic factors in TS
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