240 research outputs found
Sausage oscillations of coronal loops
Aims. Analytical theory predicts the existence of trapped global (or fundamental) sausage fast magnetoacoustic modes in thick and dense coronal loops only, with the periods estimated as the ratio of double the loop length and the Alfvén speed outside the loop. We extend this study to the leaking regime, considering global sausage modes of long loops with small density contrasts.
Methods. Anti-symmetric fast magnetoacoustic perturbations (sausage, or m = 0 modes) of a low β plasma slab with the symmetric Epstein profile of plasma density are modelled numerically.
Results. It was found that long loops with sufficiently small density contrast can support global sausage leaky modes of detectable quality. The periods of the leaky modes are found to be approximately determined by the loop length and the external Alfvén speed. If the loop length can be estimated from imaging observations, the observed period of this mode provides us with the information about the Alfvén speed outside the loop. For typical flaring coronal loops, the estimated periods of the global sausage modes are
about 5−60 s
ACUTE KIDNEY INJURY: HISTORICAL ASPECTS AND DIAGNOSTIC CRITERIA
The in-depth review is dedicated to the acute kidney injury. This conception is wider than acute renal failure. Even minor decline of renal function bias outcomes, so early diagnosis of acute renal injury is exceedingly important. The new markers of kidney injury are actively investigated. RIFLE criteria provide universal approach to a problem at first, and allow comparison of study results at second
On relativization of the Sommerfeld-Gamow-Sakharov factor
The Sommerfeld-Gamow-Sakharov factor is considered for the general case of
arbitrary masses and energies. It is shown that the scalar triangular one-loop
diagram gives the Coulomb singularity in radiative corrections at the
threshold. The singular part of the correction is factorized at the complete
Born cross section regardless of its partial wave decomposition. Different
approaches to generalize the factor are discussed.Comment: 9 pages, 4 figures; references and discussion are extende
Multimodality of rich clusters from the SDSS DR8 within the supercluster-void network
We study the relations between the multimodality of galaxy clusters drawn
from the SDSS DR8 and the environment where they reside. As cluster environment
we consider the global luminosity density field, supercluster membership, and
supercluster morphology. We use 3D normal mixture modelling, the
Dressler-Shectman test, and the peculiar velocity of cluster main galaxies as
signatures of multimodality of clusters. We calculate the luminosity density
field to study the environmental densities around clusters, and to find
superclusters where clusters reside. We determine the morphology of
superclusters with the Minkowski functionals and compare the properties of
clusters in superclusters of different morphology. We apply principal component
analysis to study the relations between the multimodality parametres of
clusters and their environment simultaneously. We find that multimodal clusters
reside in higher density environment than unimodal clusters. Clusters in
superclusters have higher probability to have substructure than isolated
clusters. The superclusters can be divided into two main morphological types,
spiders and filaments. Clusters in superclusters of spider morphology have
higher probabilities to have substructure and larger peculiar velocities of
their main galaxies than clusters in superclusters of filament morphology. The
most luminous clusters are located in the high-density cores of rich
superclusters. Five of seven most luminous clusters, and five of seven most
multimodal clusters reside in spider-type superclusters; four of seven most
unimodal clusters reside in filament-type superclusters. Our study shows the
importance of the role of superclusters as high density environment which
affects the properties of galaxy systems in them.Comment: 16 pages, 12 figures, 2 online tables, accepted for publication in
Astronomy and Astrophysic
Development of fruit diseases of microbial origin during storage at treatment with antioxidant compositions
Встановлено, що досліджува-
ні антиоксидантні композиції при-
гнічували розвиток епіфітних мікро-
організмів на поверхні плодів протя-
гом зберігання. Було зафіксовано під-
вищення їх стрес-толерантності.
Результати експерименту доводять
зменшення рівня щодобових втрат
від мікробіологічних захворювань у
2…3,5 разів. Найбільший позитивний
ефект при зберіганні усіх видів плодів
був отриманий при обробці компози-
цією на основі дистинолу і лецитин
SDSS DR7 superclusters. Morphology
We study the morphology of a set of superclusters drawn from the SDSS DR7. We
calculate the luminosity density field to determine superclusters from a flux-
limited sample of galaxies from SDSS DR7, and select superclusters with 300 and
more galaxies for our study. The morphology of superclusters is described with
the fourth Minkowski functional V3, the morphological signature (the curve in
the shapefinder's K1-K2 plane) and the shape parameter (the ratio of the
shapefinders K1/K2). We investigate the supercluster sample using
multidimensional normal mixture modelling, and use Abell clusters to identify
our superclusters with known superclusters and to study the large-scale
distribution of superclusters. The superclusters in our sample form three
chains of superclusters; one of them is the Sloan Great Wall. Most
superclusters have filament-like overall shapes. Superclusters can be divided
into two sets; more elongated superclusters are more luminous, richer, have
larger diameters, and a more complex fine structure than less elongated
superclusters. The fine structure of superclusters can be divided into four
main morphological types: spiders, multispiders, filaments, and multibranching
filaments. We present the 2D and 3D distribution of galaxies and rich groups,
the fourth Minkowski functional, and the morphological signature for all
superclusters. Widely different morphologies of superclusters show that their
evolution has been dissimilar. A study of a larger sample of superclusters from
observations and simulations is needed to understand the morphological variety
of superclusters and the possible connection between the morphology of
superclusters and their large-scale environment.Comment: Comments: 20 pages, 18 figures, accepted for publication in Astronomy
and Astrophysic
Estimation of deformational properties of a stratum-borehole system based on analysis of barometric and tidal responses of the water level in a borehole
ОСТРОЕ ПОВРЕЖДЕНИЕ ПОЧЕК: ИСТОРИЧЕСКИЕ АСПЕКТЫ И КРИТЕРИИ ДИАГНОСТИКИ
The in-depth review is dedicated to the acute kidney injury. This conception is wider than acute renal failure. Even minor decline of renal function bias outcomes, so early diagnosis of acute renal injury is exceedingly important. The new markers of kidney injury are actively investigated. RIFLE criteria provide universal approach to a problem at first, and allow comparison of study results at second. Острое повреждение почек (ОПП) является более широким понятием, чем острая почечная недостаточ- ность, поскольку даже незначительные изменения почечной функции оказывают существенное влияние на результаты лечения – как ближайшие, так и отдаленные. Возникновение ОПП увеличивает риск ле- тального исхода, сроки госпитализации и стоимость лечения. В последние годы особое внимание уделя- ется ранней диагностике ОПП. С этой целью исследуются новые биомаркеры. Предложенная в 2004 году классификация глубины поражения почек RIFLE обеспечивает унифицированный подход к определению ОПП и облегчает сравнение результатов различных исследований.
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