1,479 research outputs found
The course of experimental staphylococcus infection in albino mice during action of certain factors of space flight
A study was made of the effect of certain factors of space flight, acceleration and hypokinesia, on the course of experimental staphylococcus infection in mice. Combined action of hypokinesia and acceleration caused a marked depression of the phagocytic activity of leukocytes and formation of a considerable amount of alpha toxin
Multiwavelength observations of the blazar BL Lacertae: a new fast TeV γ-ray flare
Proceedings of the 35th International Cosmic Ray Conference (ICRC 2017), Busan (South Korea). Published in Proceeding of Science.Observations of fast TeV γ-ray flares from blazars reveal the extreme compactness of emitting regions in blazar jets. Combined with very-long-baseline radio interferometry measurements, they probe the structure and emission mechanism of the jet. We report on a fast TeV γ-ray flare from BL Lacertae observed by VERITAS, with a rise time of about 2.3 hours and a decay time of about 36 minutes. The peak flux at >200 GeV measured with the 4-minute binned light curve is (4.2±0.6)×10−6photonsm−2s−1, or ∼180% the Crab Nebula flux. Variability in GeV γ-ray, X-ray, and optical flux, as well as in optical and radio polarization was observed around the time of the TeV γ-ray flare. A possible superluminal knot was identified in the VLBA observations at 43 GHz. The flare constrains the size of the emitting region, and is consistent with several theoretical models with stationary shocks
Contact orderability up to conjugation
We study in this paper the remnants of the contact partial order on the
orbits of the adjoint action of contactomorphism groups on their Lie algebras.
Our main interest is a class of non-compact contact manifolds, called convex at
infinity.Comment: 28 pages, 1 figur
Correlation effects during liquid infiltration into hydrophobic nanoporous mediums
Correlation effects arising during liquid infiltration into hydrophobic
porous medium are considered. On the basis of these effects a mechanism of
energy absorption at filling porous medium by nonwetting liquid is suggested.
In accordance with this mechanism, the absorption of mechanical energy is a
result expenditure of energy for the formation of menisci in the pores on the
shell of the infinite cluster and expenditure of energy for the formation of
liquid-porous medium interface in the pores belonging to the infinite cluster
of filled pores. It was found that in dependences on the porosity and,
consequently, in dependences on the number of filled pores neighbors, the
thermal effect of filling can be either positive or negative and the cycle of
infiltration-defiltration can be closed with full outflow of liquid. It can
occur under certain relation between percolation properties of porous medium
and the energy characteristics of the liquid-porous medium interface and the
liquid-gas interface. It is shown that a consecutive account of these
correlation effects and percolation properties of the pores space during
infiltration allow to describe all experimental data under discussion
Transition phenomena in unstably stratified turbulent flows
We study experimentally and theoretically transition phenomena caused by the
external forcing from Rayleigh-Benard convection with the large-scale
circulation (LSC) to the limiting regime of unstably stratified turbulent flow
without LSC whereby the temperature field behaves like a passive scalar. In the
experiments we use the Rayleigh-B\'enard apparatus with an additional source of
turbulence produced by two oscillating grids located nearby the side walls of
the chamber. When the frequency of the grid oscillations is larger than 2 Hz,
the large-scale circulation (LSC) in turbulent convection is destroyed, and the
destruction of the LSC is accompanied by a strong change of the mean
temperature distribution. However, in all regimes of the unstably stratified
turbulent flow the ratio varies slightly (even in the range
of parameters whereby the behaviour of the temperature field is different from
that of the passive scalar). Here are the integral scales of
turbulence along x, y, z directions, T and \theta are the mean and fluctuating
parts of the fluid temperature. At all frequencies of the grid oscillations we
have detected the long-term nonlinear oscillations of the mean temperature. The
theoretical predictions based on the budget equations for turbulent kinetic
energy, turbulent temperature fluctuations and turbulent heat flux, are in
agreement with the experimental results.Comment: 14 pages, 14 figures, REVTEX4-1, revised versio
Problem Analysis for the Vegetation Diversity Project
Management of the majority of public rangeland in the Great Basin and Columbia-Snake River Plateau falls under the authority of the Bureau of Land Management. The flora of this land ranges from highly diverse native plant communities to deteriorated lands dominated by exotic annuals. Approximately nine percent of the BLM’s 78 million acres of public land in this region is degraded to such a degree that changes in land management alone will not result in significant improvement. The BLM intends to restore native plant communities on these deteriorated lands, but current revegetation techniques used to establish introduced perennial grasses are often unsuccessful in establishing native plants. On lands where native communities exist, the BLM desires to maintain and to enhance native plant diversity. Encroachment of highly competitive exotic forbs and annual grasses in native plant communities raises concern among managers over the appropriate management to maintain native communities. Coupled with these concerns are impacts on vegetation of the documented increase in CO, and of predicted global climate change. The BLM therefore recognizes the need for research to understand and solve these problems and for the results of this research to be transferred to land managers. The Great Basin and Columbia Plateau region consists of two major ecosystems: the sagebrush ecosystem, generally located in the northern half of the region; and the salt-desert shrub ecosystem, located in the southern half. These ecosystems differ greatly in their composition of plant species and in their climatic and soil conditions. Therefore, techniques developed in one ecosystem may not be directly transferred to the other ecosystem. We propose to initially concentrate studies in the Wyoming big sagebrush communities of the sagebrush ecosystem, because: (1) these communities represent a large amount of the BLM lands in Oregon, Idaho, northeastern California, Nevada and Utah; and (2) the low precipitation within these communities limits the success of standard revegetation methods. Shadscale communities of the salt-desert shrub ecosystem were given the next priority for study. These communities are a major component in four of the five participating states. Since the shadscale communities differ greatly from sagebrush communities, studies of shadscale communities will be initiated when the project reaches full funding. Similar studies to those proposed here for sagebrush communities would be conducted on this new suite of species and environmental conditions. Low sagebrush communities would be given the lowest priority and are unlikely to be initiated. Plant associations in low sagebrush and Wyoming sagebrush communities are similar and thus promising techniques for the Wyoming sagebrush communities may work well in low sagebrush communities and may be attempted later in the project
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