406 research outputs found
High Energy Gamma-ray Absorption and Cascade Emission in Nearby Starburst Galaxies
High energy gamma-ray emission from two nearby bright starburst galaxies, M82
and NGC 253, have recently been detected by Fermi, H.E.S.S., and VERITAS. Since
starburst galaxies have a high star formation rate and plenty of dust in the
central starburst region, infrared emissions are strong there. Gamma-ray
photons are absorbed by the interstellar radiation field photons via electron
and positron pair creation. The generated electron and positron pairs up
scatter the interstellar photons to very high energy gamma-ray photons via
cascade emission through inverse Compton scattering. In this paper, we evaluate
the contribution of this cascade emission to the gamma-ray spectra of M82 and
NGC 253. Although it would be difficult to see direct gamma- ray evidence of
cosmic-rays with an energy > 10 TeV due to the gamma-ray attenuation, the
resulting cascade emission would be indirect evidence. By including the cascade
component, we find that the total flux above 1 TeV increases ~18% and ~45%
compared with the absorbed flux assuming the maximum kinetic proton energy as
45.3 TeV and 512 TeV, respectively. Future gamma-ray observatories such as CTA
would be able to see the indirect evidence of cosmic-ray with an energy > 10
TeV by comparing with theoretical emission models including this cascade
effect.Comment: 5 pages, Accepted for publication in Ap
Wave functions and decay constants of and mesons in the relativistic potential model
With the decay constants of and mesons measured in experiment
recently, we revisit the study of the bound states of quark and antiquark in
and mesons in the relativistic potential model. The relativistic bound
state wave equation is solved numerically. The masses, decay constants and wave
functions of and mesons are obtained. Both the masses and decay
constants obtained here can be consistent with the experimental data. The wave
functions can be used in the study of and meson decays.Comment: more discussion added, to appear in EPJ
Cluster Expansion Approach to the Effective Potential in -Theory
We apply a truncated set of dynamical equations of motion for connected
equal-time Green functions up to the 4-point level to the investigation of
spontaneous ground state symmetry breaking in quantum field
theory. Within our momentum space discretization we obtain a second order phase
transition as soon as the connected 3-point function is included. However, an
additional inclusion of the connected 4-point function still shows a
significant influence on the shape of the effective potential and the critical
coupling.Comment: 1 compressed uuencoded postscript file with 5 figures included, 21
page
MAGIC J0616+225 as delayed TeV emission of cosmic-rays diffusing from SNR IC 443
We present a theoretical model that explains the high energy phenomenology of
the neighborhood of SNR IC 443, as observed with the Major Atmospheric Gamma
Imaging Cherenkov (MAGIC) telescope and the Energetic Gamma-Ray Experiment
Telescope (EGRET). We interpret MAGIC J0616+225 as delayed TeV emission of
cosmic-rays diffusing from IC 443 and interacting with a known cloud located at
a distance of about 20 pc in the foreground of the remnant. This scenario
naturally explains the displacement between EGRET and MAGIC sources, their
fluxes, and their spectra. We compare this model with others recently
presented, and discuss how it can be tested with observations by the Gamma-ray
Large Area Telescope (GLAST).Comment: Accepted for publication in MNRAS Letter
Familial aggregation of gout and relative genetic and environmental contributions: a nationwide population study in Taiwan
OBJECTIVE: To examine familial aggregation of gout and to estimate the heritability and environmental contributions to gout susceptibility in the general population.
METHODS: Using data from the National Health Insurance (NHI) Research Database in Taiwan, we conducted a nationwide cross-sectional study of data collected from 22 643 748 beneficiaries of the NHI in 2004; among them 1 045 059 individuals had physician-diagnosed gout. We estimated relative risks (RR) of gout in individuals with affected first-degree and second-degree relatives and relative contributions of genes (heritability), common environment shared by family members and non-shared environment to gout susceptibility.
RESULTS: RRs for gout were significantly higher in individuals with affected first-degree relatives (men, 1.91 (95% CI 1.90 to 1.93); women, 1.97 (95% CI 1.94 to 1.99)) and also in those with affected second-degree relatives (men, 1.27 (95% CI 1.23 to 1.31); women, 1.40 (95% CI 1.35 to 1.46)). RRs (95% CIs) for individuals with an affected twin, sibling, offspring, parent, grandchild, nephew/niece, uncle/aunt and grandparent were 8.02 (6.95 to 9.26), 2.59 (2.54 to 2.63), 1.96 (1.95 to 1.97), 1.93 (1.91 to 1.94), 1.48 (1.43 to 1.53), 1.40 (1.32 to 1.47), 1.31 (1.24 to 1.39), and 1.26 (1.21 to 1.30), respectively. The relative contributions of heritability, common and non-shared environmental factors to phenotypic variance of gout were 35.1, 28.1 and 36.8% in men and 17.0, 18.5 and 64.5% in women, respectively.
CONCLUSIONS: This population-based study confirms that gout aggregates within families. The risk of gout is higher in people with a family history. Genetic and environmental factors contribute to gout aetiology, and the relative contributions are sexually dimorphic
Assessment of biotransfer and bioaccumulation of cadmium, lead and zinc from fly ash amended soil in mustard-aphid-beetle food chain.
The present study investigates the extent of biotransfer and bioaccumulation of cadmium (Cd), lead (Pb) and zinc (Zn) from fly ash amended soil in mustard (Brassica juncea)-aphid (Lipaphis erysimi)-beetle (Coccinella septempunctata) food chain and its subsequent implications for the beetle. The soil was amended with fly ash at the rates of 0, 5, 10, 20 and 40% (w/w). Our results showed that the uptake of Cd, Pb and Zn from soil to mustard root increased with the increase in fly ash application rates, but their root to shoot translocation was relatively restricted. Increase in chlorophyll content and dry mass of mustard plant on treatments ≥20% even at elevated accumulation of Cd (1.67mgkg(-1)), Pb (18.25mgkg(-1)) and Zn (74.45mgkg(-1) dry weight) in its shoot showed relatively higher tolerance of selected mustard cultivar to heavy metal stress. The transfer coefficient (TC(1)) of Cd from mustard shoot to aphid was always >1, indicating that Cd biomagnified in aphids at second trophic level. But, there was no biomagnification of Cd in adult beetles at third trophic level. Zinc accumulation was 2.06 to 2.40 times more in aphids than their corresponding host shoots and 1.26-1.35 times more in adult beetles than their prey (aphids) on which they fed. Lead was only metal whose TC was 0.05) biomass and predation rate of predatory beetles indicated that all levels of soil amendments with fly ash did not have any lethal or sub-lethal effects on beetles
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