3,734 research outputs found
Proteomic analysis of the rat ovary following chronic low-dose exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)
2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a ubiquitously distributed endocrine-disrupting chemical and reproductive toxicant. In order to elucidate low-dose TCDD-mediated effects on reproductive or endocrine functions, female Sprague-Dawley rats were orally administered various concentrations (20, 50, or 125 ng/kg once weekly) TCDD for 29 wk. A proteomic analysis of the ovaries by two-dimensional gel electrophoresis and matrix-assisted laser desorption/ionization (MALDI) tandem mass spectrometry showed distinct changes in the levels of several proteins that are relevant markers of TCDD toxicity. Serum estradiol (E2) levels of TCDD-treated animals were markedly lower than control. There were no significant differences in bone mineral density (BMD) of femurs. The body weight of the 125-ng/kg TCDD group was significantly decreased relative to control and there was also a significant reduction in absolute and relative ovarian weights. Expressions of selenium binding protein 2, glutathione S-transferase mu type 3, Lrpap1 protein, NADPH, and peptidylprolyl isomerase D were upregulated, while prohibitin and N-ethylmaleimide-sensitive factor expression levels were downregulated. Data provide further insight into the mechanisms by which TCDD disrupts ovarian function by indicating which differential protein expressions following low-dose TCDD exposure
Schramm-Loewner Equations Driven by Symmetric Stable Processes
We consider shape, size and regularity of the hulls of the chordal
Schramm-Loewner evolution driven by a symmetric alpha-stable process. We obtain
derivative estimates, show that the complements of the hulls are Hoelder
domains, prove that the hulls have Hausdorff dimension 1, and show that the
trace is right-continuous with left limits almost surely.Comment: 22 pages, 4 figure
Entropy spectrum of a Kerr anti-de Sitter black hole
The entropy spectrum of a spherically symmetric black hole was derived
without the quasinormal modes in the work of Majhi and Vagenas. Extending this
work to rotating black holes, we quantize the entropy and the horizon area of a
Kerr anti-de Sitter black hole by two methods. The spectra of entropy and area
are obtained via the Bohr-Sommerfeld quantization rule and the adiabatic
invariance in the first way. By addressing the wave function of emitted
(absorbed) particles, the entropy and the area are quantized in the second one.
Both results show that the entropy and the area spectra are equally spaced.Comment: Accepted for publication in The European Physical Journal C, Volume
72, Issue
Hawking radiation of nonsingular black holes in two dimensions
In this letter we study the process of Hawking radiation of a black hole
assuming the existence of a limiting physical curvature scale. The particular
model is constructed using the Limiting Curvature Hypothesis (LCH) and in the
context of two-dimensional dilaton gravity. The black hole solution exhibits
properties of the standard Schwarzschild solution at large values of the radial
coordinate. However, near the center, the black hole is nonsingular and the
metric becomes that of de Sitter spacetime. The Hawking temperature is
calculated using the method of complex paths. We find that such black holes
radiate eternally and never completely evaporate. The final state is an
eternally radiating relic, near the fundamental scale, which should make a
viable dark matter candidate. We briefly comment on the black hole information
loss problem and the production of such black holes in collider experiments.Comment: 8 pages, 4 figures; minor revisions; references added; version to
appear in JHE
Effects of acceleration on the collision of particles in the rotating black hole spacetime
We study the collision of two geodesic particles in the accelerating and
rotating black hole spacetime and probe the effects of the acceleration of
black hole on the center-of-mass energy of the colliding particles and on the
high-velocity collision belts. We find that the dependence of the
center-of-mass energy on the acceleration in the near event-horizon collision
is different from that in the near acceleration-horizon case. Moreover, the
presence of the acceleration changes the shape and position of the
high-velocity collision belts. Our results show that the acceleration of black
holes brings richer physics for the collision of particles.Comment: 7 pages, 2 figures, The corrected version accepted for publication in
EPJ
De Sitter Thermodynamics from Diamonds's Temperature
The thermal time hypothesis proposed by Rovelli [1] regards the physical
basis for the flow of time as thermodynamical and provides a definition of the
temperature for some special cases. We verify this hypothesis in the case of de
Sitter spacetime by relating the uniformly accelerated observer in de Sitter
spacetime to the diamond in Minkowski spacetime. Then, as an application of it,
we investigate the thermal effect for the uniformly accelerated observer with a
finite lifetime in dS spacetime, which generalizes the corresponding result for
the case of Minkowski spacetime [2].
Furthermore, noticing that a uniformly accelerated dS observer with a finite
lifetime corresponds to a Rindler observer with a finite lifetime in the
embedding Minkowski spacetime, we show that the
global-embedding-Minkowski-spacetime (GEMS) picture of spacetime thermodynamics
is valid in this case. This is a rather nontrivial and unexpected
generalization of the GEMS picture, as well as a further verification of both
the thermal time hypothesis and the GEMS picture.Comment: 10 pages, 3 figures, LaTeX; v2: reorganized with a new section added
concerning a generalization of the GEMS picture from our result; v3: version
with minor corrections, to appear in JHE
Observations of Coronal Mass Ejections with the Coronal Multichannel Polarimeter
The Coronal Multichannel Polarimeter (CoMP) measures not only the
polarization of coronal emission, but also the full radiance profiles of
coronal emission lines. For the first time, CoMP observations provide
high-cadence image sequences of the coronal line intensity, Doppler shift and
line width simultaneously in a large field of view. By studying the Doppler
shift and line width we may explore more of the physical processes of CME
initiation and propagation. Here we identify a list of CMEs observed by CoMP
and present the first results of these observations. Our preliminary analysis
shows that CMEs are usually associated with greatly increased Doppler shift and
enhanced line width. These new observations provide not only valuable
information to constrain CME models and probe various processes during the
initial propagation of CMEs in the low corona, but also offer a possible
cost-effective and low-risk means of space weather monitoring.Comment: 6 figures. Will appear in the special issue of Coronal Magnetism,
Sol. Phy
An Asymmetric Cone Model for Halo Coronal Mass Ejections
Due to projection effects, coronagraphic observations cannot uniquely
determine parameters relevant to the geoeffectiveness of CMEs, such as the true
propagation speed, width, or source location. The Cone Model for Coronal Mass
Ejections (CMEs) has been studied in this respect and it could be used to
obtain these parameters. There are evidences that some CMEs initiate from a
flux-rope topology. It seems that these CMEs should be elongated along the
flux-rope axis and the cross section of the cone base should be rather
elliptical than circular. In the present paper we applied an asymmetric cone
model to get the real space parameters of frontsided halo CMEs (HCMEs) recorded
by SOHO/LASCO coronagraphs in 2002. The cone model parameters are generated
through a fitting procedure to the projected speeds measured at different
position angles on the plane of the sky. We consider models with the apex of
the cone located at the center and surface of the Sun. The results are compared
to the standard symmetric cone model
Characterization of latex allergenic components by capillary zone electrophoresis and N-terminal sequence analysis
In a previous study, protein components purified from latex gloves that elicited allergenic reactions were characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and yielded apparent molecular weights of 14, 22, 30, 34, 46, and 58 kD, These allergenic components were isolated for further characterization by capillary zone electrophoresis and N-terminal amino acid sequence analysis. These components all migrated at approximately 25 and 35 min on capillary zone electrophoresis, Diode array spectral analysis detected indistinguishable characteristics between these two protein peaks, In addition, complex formation of these components with patients' immunoglobulin was demonstrated by capillary zone electrophoresis. Analysis of components separated by SDS-PAGE on a polyvinylidene difluoride membrane showed that the first 13 residues were identical to the sequence of hevein, Based on the criteria of charge-to-mass ratio and N-terminal amino acid sequence, our results suggest that these components of latex proteins are similar in the primary structure
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