150 research outputs found
Determination of pKa values for the mitomycin C redox couple by titration, pH rate profiles, and nernst-Clark Fits. studies of methanol elimination, carbocation formation, and carbocation/quinone method equilibrium
A mechanistic study of 2- vinylbenzimidazole formation from 2-(2'-haloethyl) benzimidazoles. Synthesis of highly electron rich vinylic compounds by general base and specific acid - general base
A comparison of the cytotoxic and physical properties of aziridinyl quinone derivatives based on pyrrolo[1,2-a] benzimidazole and pyrrolo[1,2-a]indole ring systems
Diffuse Galactic Soft Gamma-Ray Emission
The Galactic diffuse soft gamma-ray (30-800 keV) emission has been measured
from the Galactic Center by the HIREGS balloon-borne germanium spectrometer to
determine the spectral characteristics and origin of the emission. The
resulting Galactic diffuse continuum is found to agree well with a single
power-law (plus positronium) over the entire energy range, consistent with RXTE
and COMPTEL/CGRO observations at lower and higher energies, respectively. We
find no evidence of spectral steepening below 200 keV, as has been reported in
previous observations. The spatial distribution along the Galactic ridge is
found to be nearly flat, with upper limits set on the longitudinal gradient,
and with no evidence of an edge in the observed region. The soft gamma-ray
diffuse spectrum is well modeled by inverse Compton scattering of interstellar
radiation off of cosmic-ray electrons, minimizing the need to invoke
inefficient nonthermal bremsstrahlung emission. The resulting power requirement
is well within that provided by Galactic supernovae. We speculate that the
measured spectrum provides the first direct constraints on the cosmic-ray
electron spectrum below 300 MeV.Comment: 26 pages, 7 figure, submitted to Ap
Simultaneous EUV and X-ray variability of NGC 4051
We present a flux variability study of simultaneous RXTE and EUVE
observations of the highly variable Seyfert galaxy NGC4051. We find a strong
correlation between variability in the EUV and medium energy X-ray
bands,indicating that both are sampling the same power-law continuum. The lag
between the two bands is less than 20 ks and, depending on model assumptions,
may be <1 ks. We examine the consequences of such a small lag in the context of
simple Comptonisation models for the production of the power-law continuum. A
lag of <1 ks implies that the size of the Comptonising region is less than 20
Schwarzschild radii for a black hole of mass >1E6 solar masses.Comment: 8 pages, accepted for publication in MNRA
Biochemical and immunological markers of autoimmune thyroiditis
© 2015, Pleiades Publishing, Ltd. Correlations between biochemical and immunological markers of programmed cell death (apoptosis), and the functional state of the thyroid gland (hyperthyroidism, euthyroidism, hypothyroidism) have been investigated in autoimmune thyroiditis (AT) (also known as chronic autoimmune thyroiditis). Annexin V, TRAIL and TNFα, as well as DNA-hydrolyzing antibodies were used as the main markers. Increased levels of TRAIL were found in the serum of AT patients (hyperthyroidism > hypothyroidism > euthyroidism) compared with healthy individuals. The highest frequency of antibodies to denatured DNA (Abs-dDNA) had the highest frequency in AT patients (97%) compared with healthy controls. Among these patients, 75% had hyperthyroidism, 85% had hypothyroidism, and 84.7% had euthyroidism. Abs hydrolyzing activity demonstrated correlation dependence with symptoms of the thyroid dysfunction
Biochemical & immunological markers of autoimmune thyroiditis
Correlations between biochemical and immunological markers of programmed cell death (apoptosis), and the functional state of the thyroid gland (hyperthyroidism, euthyroidism, hypothyroidism) have been investigated in autoimmune thyroiditis (AT) (also known as chronic autoimmune thyroiditis). Annexin V, TRAIL and TNF-α, as well as DNA-hydrolyzing antibodies were used as the main markers. Increased levels of TRAIL were found in the serum of AT patients (hyperthyroidism>hypothyroidism>euthyroidism) compared with healthy individuals. The highest frequency of antibodies to denatured DNA (Abs-dDNA) had the highest frequency in AT patients (97%) compared with healthy controls. Among these patients, 75% had hyperthyroidism, 85% had hypothyroidism, and 84.7% had euthyroidism. Abs hydrolyzing activity demonstrated correlation dependence with symptoms of the thyroid dysfunction
OSSE Observations of the Soft Gamma Ray Continuum from the Galactic Plane at Longitude 95 Degrees
We present the results of OSSE observations of the soft gamma ray continuum
emission from the Galactic plane at longitude 95 degrees. Emission is detected
between 50 and 600 keV where the spectrum is fit well by a power law with
photon index -2.6+-0.3 and flux (4.0+-0.5) 10^{-2} photons/s/cm^2/rad/MeV at
100 keV. This spectral shape in this range is similar to that found for the
continuum emission from the inner Galaxy but the amplitude is lower by a factor
of four. This emission is either due to unresolved and previously unknown point
sources or it is of diffuse origin, or a combination of the two. Simultaneous
observations with OSSE and smaller field of view instruments operating in the
soft gamma ray energy band, such as XTE or SAX, would help resolve this issue.
If it is primarily diffuse emission due to nonthermal electron bremsstrahlung,
as is the >1 MeV Galactic ridge continuum, then the power in low energy cosmic
ray electrons exceeds that of the nuclear component of the cosmic rays by an
order of magnitude. This would have profound implications for the origin of
cosmic rays and the energetics of the interstellar medium. Alternatively, if
the emission is diffuse and thermal, then there must be a component of the
interstellar medium at temperatures near 10^9 K.Comment: 11 pages, Latex, requires AASTEX macros and psfig.tex, 2 postscript
figures, Accepted for publication in the Astrophysical Journal Letter
Measurement Of the Galactic X-ray/Gamma-ray Background Radiation: Contribution of Discrete Sources
The Galactic background radiation near the Scutum Arm was observed
simultaneously with RXTE and OSSE in order to determine the spectral shape and
the origin of the emission in the hard X-ray/soft gamma-ray band. The spectrum
in the 3 keV to 1 MeV band is well modeled by 4 components: a high energy
continuum dominating above 500 keV that can be characterized by a power law of
photon index ~ 1.6 (an extrapolation from measurements above ~ 1 MeV); a
positron annihilation line at 511 keV and positronium continuum; a variable
hard X-ray/soft gamma-ray component that dominates between 10-200 keV (with a
minimum detected flux of ~ 7.7 x 10^-7 photons cm^-2 s^-1 keV^-1 deg^-2 at 100
keV averaged over the field of view of OSSE) and that is well modeled by an
exponentially cut off power law of photon index ~ 0.6 and energy cut off at ~
41 keV; and finally a thermal plasma model of solar abundances and temperature
of 2.6 keV that dominates below 10 keV. We estimate that the contribution of
bright discrete sources to the minimum flux detected by OSSE was ~ 46% at 60
keV and ~ 20% at 100 keV. The remaining unresolved emission may be interpreted
either as truly diffuse emission with a hard spectrum (such as that from
inverse Compton scattering) or the superposition of discrete sources that have
very hard spectra.Comment: Accepted for Publication in the Astrophysical Journa
Gamma-Ray Spectral States of Galactic Black Hole Candidates
OSSE has observed seven transient black hole candidates: GRO J0422+32,
GX339-4, GRS 1716-249, GRS 1009-45, 4U 1543-47, GRO J1655-40, and GRS 1915+105.
Two gamma-ray spectral states are evident and, based on a limited number of
contemporaneous X-ray and gamma-ray observations, these states appear to be
correlated with X-ray states. The former three objects show hard spectra below
100 keV (photon number indices Gamma < 2) that are exponentially cut off with
folding energy ~100 keV, a spectral form that is consistent with thermal
Comptonization. This "breaking gamma-ray state" is the high-energy extension of
the X-ray low, hard state. In this state, the majority of the luminosity is
above the X-ray band, carried by photons of energy ~100 keV. The latter four
objects exhibit a "power-law gamma-ray state" with a relatively soft spectral
index (Gamma ~ 2.5-3) and no evidence for a spectral break. For GRO J1655-40,
the lower limit on the break energy is 690 keV. GRS 1716-249 exhibits both
spectral states, with the power-law state having significantly lower gamma-ray
luminosity. The power-law gamma-ray state is associated with the presence of a
strong ultrasoft X-ray excess (kT ~ 1 keV), the signature of the X-ray high,
soft (or perhaps very high) state. The physical process responsible for the
unbroken power law is not well understood, although the spectra are consistent
with bulk-motion Comptonization in the convergent accretion flow.Comment: 27 pages, 3 figures, uses aaspp.sty and psfig.st
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