661 research outputs found
A New Method for Calculating Arrival Distribution of Ultra-High Energy Cosmic Rays above 10^19 eV with Modifications by the Galactic Magnetic Field
We present a new method for calculating arrival distribution of UHECRs
including modifications by the galactic magnetic field. We perform numerical
simulations of UHE anti-protons, which are injected isotropically at the earth,
in the Galaxy and record the directions of velocities at the earth and outside
the Galaxy for all of the trajectories. We then select some of them so that the
resultant mapping of the velocity directions outside the Galaxy of the selected
trajectories corresponds to a given source location scenario, applying
Liouville's theorem. We also consider energy loss processes of UHE protons in
the intergalactic space. Applying this method to our source location scenario
which is adopted in our recent study and can explain the AGASA observation
above 4 \times 10^{19} eV, we calculate the arrival distribution of UHECRs
including lower energy (E>10^19 eV) ones. We find that our source model can
reproduce the large-scale isotropy and the small-scale anisotropy on UHECR
arrival distribution above 10^19 eV observed by the AGASA. We also demonstrate
the UHECR arrival distribution above 10^19 eV with the event number expected by
future experiments in the next few years. The interesting feature of the
resultant arrival distribution is the arrangement of the clustered events in
the order of their energies, reflecting the directions of the galactic magnetic
field. This is also pointed out by Alvarez-Muniz et al.(2002). This feature
will allow us to obtain some kind of information about the composition of
UHECRs and the magnetic field with increasing amount of data.Comment: 10 pages, 8 figures, to appear in the Astrophysical Journa
N -Ethyl- N -Nitrosourea Induces Retinal Photoreceptor Damage in Adult Rats
Seven-week-old male Lewis rats received a single intraperitoneal injection of N-ethyl-N-nitrosourea (ENU) (100, 200, 400 or 600 mg/kg), and retinal damage was evaluated 7 days after the treatment. Sequential morphological features of the retina and retinal DNA damage, as determined by a TUNEL assay and phospho-histone H2A.X (γ-H2AX), were analyzed 3, 6, 12, 24 and 72 hr, 7 days, and/or 30 days after 400 mg/kg ENU treatment. Activation of the nuclear enzyme poly (ADP-ribose) polymerase (PARP) was analyzed immunohistochemically by poly (ADP-ribose) (PAR) expression in response to DNA damage of the retina. All rats that received ≥ 400 mg/kg of ENU developed retinal degeneration characterized by the loss of photoreceptor cells in both the central and peripheral retina within 7 days. In the 400 mg/kg ENU-treated rats, TUNEL-positive signals were only located in the photoreceptor cells and peaked 24 hr after ENU treatment. The γ-H2AX signals in inner retinal cells appeared at 24 hr and peaked at 72 hr after ENU treatment, and the PAR signals selectively located in the photoreceptor cell nuclei appeared at 12 hr and peaked at 24 hr after ENU treatment. However, degeneration was restricted to photoreceptor cells, and no degenerative changes in inner retinal cells were seen at any time points. Retinal thickness and the photoreceptor cell ratio in the central and peripheral retina were significantly decreased, and the retinal damage ratio was significantly increased 7 days after ENU treatment. In conclusion, ENU induced retinal degeneration in adult rats that was characterized by photoreceptor cell apoptosis through PARP activity
Autoimmune Pancreatitis Accompanied by Cholecystitis, Periaortitis and Pseudotumors of the Liver
A variety of extrapancreatic lesions have been associated with autoimmune pancreatitis (AIP), and these lesions can be difficult to diagnose. We report a patient referred to Shizuoka Cancer Center with the diagnosis of a possible biliary carcinoma with liver metastasis who was shown to have AIP accompanied by pseudotumors of liver. Clinical imaging revealed diffuse enlargement of the head of the pancreas with irregular narrowing of the main pancreatic duct and inferior common bile duct, multiple liver masses, mediastinal lymphadenopathy, and thickening of the wall of the gallbladder and abdominal aorta. Cytology and biopsy from the pancreaticobiliary tract was negative for malignancy. Serum carcinoembryonic antigen (CEA) and carbohydrate antigen (CA19-9) levels were in the normal range, but soluble interleukin 2 receptor (sIL2R), IgG4 and antinuclear antibody were abnormally high (sIL2R: 2,550 U/ml; IgG4: 764 mg/dl). Corticosteroid therapy was effective and these abnormal findings all improved. This case demonstrates the clinical importance of AIP accompanied by other systemic disorders in the differential diagnosis of patients with a pancreatic mass lesion
Evolution Equation of Phenotype Distribution: General Formulation and Application to Error Catastrophe
An equation describing the evolution of phenotypic distribution is derived
using methods developed in statistical physics. The equation is solved by using
the singular perturbation method, and assuming that the number of bases in the
genetic sequence is large. Applying the equation to the mutation-selection
model by Eigen provides the critical mutation rate for the error catastrophe.
Phenotypic fluctuation of clones (individuals sharing the same gene) is
introduced into this evolution equation. With this formalism, it is found that
the critical mutation rate is sometimes increased by the phenotypic
fluctuations, i.e., noise can enhance robustness of a fitted state to mutation.
Our formalism is systematic and general, while approximations to derive more
tractable evolution equations are also discussed.Comment: 22 pages, 2 figure
North-South Neutrino Heating Asymmetry in Strongly Magnetized and Rotating Stellar Cores
We perform a series of two-dimensional magnetohydrodynamic simulations of
supernova cores. Since the distributions of the angular momentum and the
magnetic fields of strongly magnetized stars are quite uncertain, we
systematically change the combinations of the strength of the angular momentum,
the rotations law, the degree of differential rotation, and the profiles of the
magnetic fields to construct the initial conditions. By so doing, we estimate
how the rotation-induced anisotropic neutrino heating are affected by the
strong magnetic fields through parity-violating effects and first investigate
how the north-south asymmetry of the neutrino heating in a strongly magnetized
supernova core could be. As for the microphysics, we employ a realistic
equation of state based on the relativistic mean field theory and take into
account electron captures and the neutrino transport via the neutrino leakage
scheme. With these computations, we find that the parity-violating corrections
reduce of the neutrino heating rate than that without the
magnetic fields in the vicinity of the north pole of a star, on the other hand,
enhance about in the vicinity of the south pole. If the
global asymmetry of the neutrino heating in the both of the poles develops in
the later phases, the newly born neutron star might be kicked toward the north
pole in the subsequent time.Comment: 25 pages, 6 figures, ApJ in press. A paper with higher-resolution
figures available at
http://www-utap.phys.s.u-tokyo.ac.jp/~kkotake/lonbun.htm
Measurement of Residual Stresses Around a Circular Patch Weld Using Barkhausen Noise
Welding is a common means of joining and repairing steel structures. In the case of steel tanks, circular patch welds are often used for repairing the structure after removal of a defective area. Unfortunately, the welding process also produces residual stresses which, if not relieved, can impair the integrity of the structure. Measurement of residual stresses produced by welding is needed, for example, to verify the effectiveness of a stress relief heat treatment which is typically used to remove weld-induced stresses
Statin-induced mevalonate pathway inhibition attenuates the growth of mesenchymal-like cancer cells that lack functional E-cadherin mediated cell cohesion
The cholesterol reducing drugs, statins, exhibit anti-tumor effects against cancer stem cells and various cancer cell lines, exert potent additivity or synergy with existing chemotherapeutics in animal models of cancer and may reduce cancer incidence and cancer related mortality in humans. However, not all tumor cell lines are sensitive to statins, and clinical trials have demonstrated mixed outcomes regarding statins as anticancer agents. Here, we show that statin-induced reduction in intracellular cholesterol levels correlate with the growth inhibition of cancer cell lines upon statin treatment. Moreover, statin sensitivity segregates with abundant cytosolic vimentin expression and absent cell surface E-cadherin expression, a pattern characteristic of mesenchymal-like cells. Exogenous expression of cell surface E-cadherin converts statin- sensitive cells to a partially resistant state implying that statin resistance is in part dependent on the tumor cells attaining an epithelial phenotype. As metastasizing tumor cells undergo epithelial to mesenchymal transition during the initiation of the metastatic cascade, statin therapy may represent an effective approach to targeting the cells most likely to disseminate
Effects of Neutrino Oscillation on the Supernova Neutrino Spectrum
The effects of three-flavor neutrino oscillation on the supernova neutrino
spectrum are studied. We calculate the expected event rate and energy spectra,
and their time evolution at the Superkamiokande (SK) and the Sudbury Neutrino
Observatory (SNO), by using a realistic neutrino burst model based on numerical
simulations of supernova explosions. We also employ a realistic density profile
based on a presupernova model for the calculation of neutrino conversion
probability in supernova envelopes. These realistic models and numerical
calculations allow us to quantitatively estimate the effects of neutrino
oscillation in a more realistic way than previous studies. We then found that
the degeneracy of the solutions of the solar neutrino problem can be broken by
the combination of the SK and SNO detections of a future Galactic supernova.Comment: 10 pages, 14 figures, corrected versio
Microscopic Study of Slablike and Rodlike Nuclei: Quantum Molecular Dynamics Approach
Structure of cold dense matter at subnuclear densities is investigated by
quantum molecular dynamics (QMD) simulations. We succeeded in showing that the
phases with slab-like and rod-like nuclei etc. can be formed dynamically from
hot uniform nuclear matter without any assumptions on nuclear shape. We also
observe intermediate phases, which has complicated nuclear shapes. Geometrical
structures of matter are analyzed with Minkowski functionals, and it is found
out that intermediate phases can be characterized as ones with negative Euler
characteristic. Our result suggests the existence of these kinds of phases in
addition to the simple ``pasta'' phases in neutron star crusts.Comment: 6 pages, 4 figures, RevTex4; to be published in Phys. Rev. C Rapid
Communication (accepted version
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