23,091 research outputs found
Surveyor landing radar test program review Final report
Test program evaluation and modifications for Surveyor radar altimeter and Doppler velocity sensor syste
Modelling Hen Harrier Dynamics to Inform Human-Wildlife Conflict Resolution : A Spatially-Realistic, Individual-Based Approach
Peer reviewedPublisher PD
Gravitational Laser Back-Scattering
A possible way of producing gravitons in the laboratory is investigated. We
evaluate the cross section electron + photon electron + graviton
in the framework of linearized gravitation, and analyse this reaction
considering the photon coming either from a laser beam or from a Compton
back-scattering process.Comment: 11 pages, 2 figures (available upon request), RevTeX, IFT-P.03/9
Seasonal distribution and drivers of surface fine particulate matter and organic aerosol over the Indo-Gangetic Plain
The Indo-Gangetic Plain (IGP) is home to 9â% of the global population and is responsible for a
large fraction of agricultural crop production in Pakistan, India, and Bangladesh. Levels of fine particulate matter (mean diameterâ<2.5â”m, PM2.5)
across the IGP often exceed human health recommendations, making
cities across the IGP among the most polluted in the world. Seasonal
changes in the physical environment over the IGP are dominated by the
large-scale south Asian monsoon system that dictates the timing of
agricultural planting and harvesting. We use the WRF-Chem model to study the seasonal anthropogenic,
pyrogenic, and biogenic influences on fine particulate matter and its
constituent organic aerosol (OA) over the IGP
that straddles Pakistan, India, and Bangladesh during 2017â2018. We find that surface air quality
during pre-monsoon (MarchâMay) and monsoon (JuneâSeptember) seasons is
better than during post-monsoon (OctoberâDecember) and winter
(JanuaryâFebruary) seasons, but all seasonal mean values of PM2.5
still exceed the recommended levels, so that air pollution is a year-round problem. Anthropogenic
emissions influence the magnitude and distribution of PM2.5 and
OA throughout the year, especially over urban sites, while pyrogenic
emissions result in localised contributions over the central and upper
parts of IGP in all non-monsoonal seasons, with the highest impact during
post-monsoon seasons that correspond to the post-harvest season in the
agricultural calendar. Biogenic emissions play an important role in
the magnitude and distribution of PM2.5 and OA during the monsoon
season, and they show a substantial contribution to secondary OA (SOA),
particularly over the lower IGP. We find that the OA contribution to
PM2.5 is significant in all four seasons (17â%â30â%), with primary
OA generally representing the larger fractional contribution. We find
that the volatility distribution of SOA is driven mainly by the mean
total OA loading and the washout of aerosols and gas-phase aerosol
precursors that result in SOA being less volatile during the
pre-monsoon and monsoon season than during the post-monsoon and winter
seasons.</p
The active metabolite of leflunomide, A77 1726, increases proliferation of human synovial fibroblasts in presence of IL-1ÎČ and TNF-α
Abstract.: Objective and design: Excessive synovial fibroblast (SF) proliferation is detrimental in rheumatoid arthritis. We therefore sought to determine the effects of A77 1726, the active metabolite of leflunomide, on SF proliferation. Methods: Human SFs were used. Cell proliferation was investigated using MTS assay, by 3H-thymidine incorporation and cell counts. Results: Whereas A77 1726 alone had no effects, it significantly increased the mitogenic effects of interleukin-1ÎČ (IL-1ÎČ) and tumor necrosis factor-α (TNF-α). Cyclooxygenase inhibition might be at least partly involved, since indomethacin displayed similar effects, and since prostaglandin E2 inhibited SF proliferation. In contrast, the effect of A77 1726 did not appear to be mediated through depletion of the pyrimidine pool or inhibition of tyrosine kinases. Conclusion: A77 1726 displays proliferative effects in presence of IL-1ÎČ and TNF-α. Further elucidation of involved mechanisms may prove useful for the utilization of leflunomide, the development of related compounds or elaboration of new therapeutic strategie
Defining the interaction of the protease CpaA with its type II secretion chaperone CpaB and its contribution to virulence in Acinetobacter species
Metastable States in High Order Short-Range Spin Glasses
The mean number of metastable states in higher order short-range spin
glasses is estimated analytically using a variational method introduced by
Tanaka and Edwards for very large coordination numbers. For lattices with small
connectivities, numerical simulations do not show any significant dependence on
the relative positions of the interacting spins on the lattice, indicating thus
that these systems can be described by a few macroscopic parameters. As an
extremely anisotropic model we consider the low autocorrelated binary spin
model and we show through numerical simulations that its landscape has an
exceptionally large number of local optima
Numerical Simulations of Globular Cluster Formation
We examine various physical processes associated with the formation of
globular clusters by using the three-dimensional Smoothed Particle
Hydrodynamics (SPH) code. Our code includes radiative cooling of gases, star
formation, energy feedback from stars including stellar winds and supernovae,
and chemical enrichment by stars. We assume that, in the collapsing galaxy,
isothermal cold clouds form through thermal condensations and become
proto-globular clouds. We calculate the size of proto-globular clouds by
solving the linearized equations for perturbation. We compute the evolution of
the inner region of the proto-cloud with our SPH code for various initial
radius and initial composition of gases. When the initial gases contain no
heavy elements, the evolution of proto-clouds sensitively depends on the
initial radius. For a smaller initial radius, the initial star burst is so
intense that the subsequent star formation occurs in the central regions to
form a dense star cluster as massive as the globular cluster. When the initial
gases contain some heavy elements, the metallicity of gases affects the
evolution and the final stellar mass. If the initial radius of the
proto-globular clouds was relatively large, the formation of a star cluster as
massive as the globular clusters requires the initial metallicity as high as
[Fe/H] . The self-enrichment of heavy elements in the star cluster
does not occur in all cases.Comment: Accpeted for publication in the ApJ. Correctiong errors in Table
- âŠ