6,699 research outputs found
How Will the Patient Protection and Affordable Care Act of 2010 Affect Young Adults?
Summarizes how healthcare reform provisions including the expansion of dependent coverage, subsidies for insurance premiums, and penalties for opting out of coverage will affect young adults ages 19-29 by income level and gender
A closed form for the electrostatic interaction between two rod-like charged objects
We have calculated the electrostatic interaction between two rod-like charged
objects with arbitrary orientations in three dimensions. we obtained a closed
form formula expressing the interaction energy in terms of the separation
distance between the centers of the two rod-like objects, , their lengths
(denoted by and ), and their relative orientations (indicated by
and ). When the objects have the same length (),
for particular values of separations, i.e for , two types of
minimum are appeared in the interaction energy with respect to . By
employing the closed form formula and introducing a scaled temperature , we
have also studied the thermodynamic properties of a one dimensional system of
rod-like charged objects. For different separation distances, the dependence of
the specific heat of the system to the scaled temperature has been studied. It
is found that for , the specific heat has a maximum.Comment: 10 pages, 9 figures, 1 table, Accepted by J. Phys.: Condens. Matte
Nimesulide reduces interleukin-1β-induced cyclooxygenase-2 gene expression in human synovial fibroblasts
AbstractObjective To characterize the effects of nimesulide (NIM) on basal and induced cyclo-oxygenase-2 (COX-2) gene expression in human synovial fibroblasts (HSF) and to define the intracellular mechanisms that mediate the changes in COX-2 expression and synthesis in response to the drug.Design HSF were incubated with NIM and NS-398 (0, 0.03, 0.3, 3μg/ml) in the absence or presence of the COX-2 inducers interleukin-1β (IL-1β) or endotoxin (LPS). Treated cells were analysed for COX-2 mRNA and protein by Northern and Western blotting analysis, respectively. Putative transcriptional, post-transcriptional, and signaling effects of NIM on basal and induced-COX-2 expression were investigated by human COX-2 promoter studies, calcium studies, reactive oxygen species (ROS) evaluations, electrophoretic mobility shift analysis (EMSA) and half-life studies of COX-2 mRNA.Results NIM inhibited IL-1β-induced COX-2 expression and protein at sub and therapeutic concentrations (0.03–0.3μg/ml) while the non-specific NSAID, naproxen, did not. Both drugs suppressed PGE2 release by about 95%. NIM had no effect on (1) IL-1β-induced increases in NF-κB or c/EBP signaling, or (2) human COX-2 promoter activity. Stability of induced COX-2 mRNA was unaffected by NIM treatments. Pre-treatment of cells with O2radical scavengers (e.g. PDTC) or with Ca++channel blockers (e.g. verapamil) had a modest effect on IL-1β-induced COX-2 expression. NIM blocked ionomycin+thapsigargin and H2O2-induced increases in COX-2 protein synthesis.Conclusion NIM inhibits cytokine-induced COX-2 expression and protein at sub and therapeutic concentrations. At least part of this activity may be the result of NIM inhibition of calcium and/or free radical generation induced by cytokines
Inhibition of Tendon Cell Proliferation and Matrix Glycosaminoglycan Synthesis by Non-Steroidal Anti-Inflammatory Drugs in vitro
The purpose of this study was to investigate the effects of some commonly used non-steroidal anti-inflammatory drugs (NSAIDs) on human tendon. Explants of human digital flexor and patella tendons were cultured in medium containing pharmacological concentrations of NSAIDs. Cell proliferation was measured by incorporation of 3H-thymidine and glycosaminoglycan synthesis was measured by incorporation of 35S-Sulphate. Diclofenac and aceclofenac had no significant effect either on tendon cell proliferation or glycosaminoglycan synthesis. Indomethacin and naproxen inhibited cell proliferation in patella tendons and inhibited glycosaminoglycan synthesis in both digital flexor and patella tendons. If applicable to the in vivo situation, these NSAIDs should be used with caution in the treatment of pain after tendon injury and surgery
Transport of Cosmic Rays in Chaotic Magnetic Fields
The transport of charged particles in disorganised magnetic fields is an
important issue which concerns the propagation of cosmic rays of all energies
in a variety of astrophysical environments, such as the interplanetary,
interstellar and even extra-galactic media, as well as the efficiency of Fermi
acceleration processes. We have performed detailed numerical experiments using
Monte-Carlo simulations of particle propagation in stochastic magnetic fields
in order to measure the parallel and transverse spatial diffusion coefficients
and the pitch angle scattering time as a function of rigidity and strength of
the turbulent magnetic component. We confirm the extrapolation to high
turbulence levels of the scaling predicted by the quasi-linear approximation
for the scattering frequency and parallel diffusion coefficient at low
rigidity. We show that the widely used Bohm diffusion coefficient does not
provide a satisfactory approximation to diffusion even in the extreme case
where the mean field vanishes. We find that diffusion also takes place for
particles with Larmor radii larger than the coherence length of the turbulence.
We argue that transverse diffusion is much more effective than predicted by the
quasi-linear approximation, and appears compatible with chaotic magnetic
diffusion of the field lines. We provide numerical estimates of the Kolmogorov
length and magnetic line diffusion coefficient as a function of the level of
turbulence. Finally we comment on applications of our results to astrophysical
turbulence and the acceleration of high energy cosmic rays in supernovae
remnants, in super-bubbles, and in jets and hot spots of powerful
radio-galaxies.Comment: To be published in Physical Review D, 20 pages 9 figure
High Energy Emission and Cosmic Rays from Gamma-Ray Bursts
The paper is devoted to the analysis of particle acceleration in Gamma-Ray
Bursts and its radiative consequences. Therefore we get on one hand constraints
on the physics and on the other hand possible signatures of particle
acceleration that could be recorded by the new gamma ray instruments. We have
previously shown that UHECRs can be generated in GRBs even with conservative
assumptions on the magnetic field and the scattering capability of its
perturbations, provided that a suitable relativistic Fermi process is at work
during the so-called "internal shock" phase. We extend here the analysis of the
consequences of these assumptions to the whole prompt emission of both
electrons and protons. Indeed, assuming that the magnetic field decays in
and that the scattering time of particles is longer than the Bohm's
assumption, in particular with a rule derived from Kolmogorov scaling, we show
with no other parameter adaptation that the intensity of the subequipartition
magnetic field, that: i) UHECRs can be generated with a sufficient flux within
the GZK-sphere to account for the CR-spectrum at the ankle. ii) The peak energy
of the gamma spectrum around 100 keV, namely the so-called , is
conveniently explained. iii) A thermal component below the is often
unavoidable. iv) The cosmic rays could radiate gamma rays around 67 MeV (in the
co-moving frame, which implies GeV for the observer) due to
-decay and a low energy neutrino emission (around 0.2 GeV) associated to
neutron decay and also neutrinos of energy between 5 and 150 GeV from muon
decay. v) The UHECRs radiate high energy gamma rays between a few tens of MeV
and 10 GeV (taking the pair creation process into account) due to their
synchrotron emission with a sufficient flux to be observable.Comment: 18 pages, 3 figures, submitted to Astrophysical Journa
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