High Accretion Rate during Class 0 Phase due to External Trigger

Recent observations indicate that some class 0 sources have orders of magnitude higher accretion rates than those of class I. We investigated the conditions for the high accretion rates of some class 0 sources by numerical calculations, modelling an external trigger. For no external trigger, we find that the maximum value of the accretion rate is determined by the ratio $\alpha$ of the gravitational energy to the thermal one within a flat inner region of the cloud core. The accretion rate reaches \sim 10^{-4} M_{\sun} yr^{-1} if the cloud core has $\alpha > 2$. For an external trigger we find that the maximum value of the accretion rate is proportional to the momentum given to the cloud core. The accretion rate reaches > 10^{-4} M_{\sun} yr^{-1} with a momentum of \sim 0.1 M_{\sun} km s^{-1} when the initial central density of the cloud core is $\sim 10^{-18} g cm^{-3}$. A comparison between recent observational results for prestellar cores and our no triggered collapse model indicates that the flat inner regions of typical prestellar cores are not large enough to cause accretion rates of \sim 10^{-4} M_{\sun} yr^{-1}. Our results show that the triggered collapse of the cloud core is more preferable for the origin of the high accretion rates of class 0 sources than no triggered collapse.Comment: 7 pages, 8 figures, accepted for publication in MNRA

Polarized Parton Distribution in Neutrino Induced Heavy Flavor Production

In order to examine polarized strange quark distribution, semi-inclusive D/\Dbar production in neutrino deep inelastic scattering is studied including ${\cal O}(\alpha_s)$ corrections. Cross section and spin asymmetry are calculated by using various parametrizations of polarized parton distribution functions. It is found that \Dbar production is promising to directly extract the polarized strange sea.Comment: 3 pages, 2 figures. Talk given at the NuFact02 workshop, London, UK, July 1-6, 200

Effect of polarized gluon distribution on spin asymmetries for neutral and charged pion production

A longitudinal double spin asymmetry for \pi^0 production has been measured by the PHENIX collaboration. The asymmetry is sensitive to the polarized gluon distribution and is indicated to be positive by theoretical predictions. We study a correlation between behavior of the asymmetry and polarized gluon distribution in neutral and charged pion production at RHIC.Comment: 7 pages, 5 eps figures, section added, typos corrected. to be published in PR

Effects of Flavonoids Isolated From Orange Jasmine (Murraya Paniculata [L.] Jack.) on Histamine Release From Mast Cells

Murraya paniculata [L.] Jack. (Kemuning) is a plant that grows widely in some areas of Indonesia. Studies related to this plant have been widely explored especially isolation of its active compounds. The plant contents several active compounds such as flanovoids. In the study, three flavonoid isolated from M. paniculata were evaluated for their effect on histamine release from mast cells (RBL-2H3 cells). These compounds were 3,3',4',5,5',6,7,8-octamethoxyflavone; 3,3',4',5,5',6,7-heptamethoxyflavone and 3, 3', 4', 5, 5', 7–hexamethoxyflavone. The histamine inducers used in the study were DNP24-BSA dan thapsigargin, inducing the histamine release immunologically and non-immunologically, respectively. In the study, heptamethoxyflavone and hexamethoxyflavone did not influence the histamine release from mast cells significantly. However, octamethoxyflavone could increase the histamine release from RBL-2H3 cells in absence and presence the histamine inducers. The flavanoid could increase the release of histamine up to 50 %. Based on the results, polymethoxy moieties at the structure of flavonoid have a significant role to emerge the histamine-release stimulating effect from mast cells

Comparison of Cytotoxic and Antiproliferative Effects of Benzylidenecyclopentanone Analogues of Curcumin on RBL-2H3 Cells

Curcumin is a natural yellow pigment isolated from the rhizomes of Curcuma longa L. (turmeric), and has several pharmacological effects and no toxicity in both in animal and human clinical study. However, the problem of curcumin is its stability because of its active methylene moiety. Modification of this moiety to cyclopentanone is expected to increase the stability. Previous study reported that benzylidenecyclopentanone analogues of curcumin showed inhibitory effect on histamine release from RBL-2H3 (rat basophilic leukemia) cells, a tumor analog of mast cells. One of them, the hydroxy-methoxy analog (PGV-0), showed more potent effect than that of curcumin. In the present study, some benzylidenecyclopentanone analogues of curcumin were evaluated for their effects on the viability and proliferation of RBL-2H3 cells. Viable cells were counted under a light microscope with a cells-counting chamber or using the cell viability reagent WST-1. The results showed that mast cell viability and histamine content were not affected by curcumin and benzylidene cyclopentanone for 30 min incubation, however, impaired for overnight incubation. The hydroxy-dimethyl benzylidene analog (PGV-1) strongly decreased the mast cells viability for overnight incubation, and its effect was highest among the other analogues. In the proliferation study, this compound also strongly inhibited the proliferation of mast cells, whereas curcumin and hydroxy-methoxy benzylidene analog inhibited the proliferation slightly. There were no inhibitory effects on mast cells proliferation treated by dibenzylidene; dihydroxybenzylidene; and hydroxy-diethylbenzylidene cyclopentanone. Keywords : viability, proliferation, curcumin, benzylidene cyclopentanone, RBL-2H3 cell

Spectral Evolutions in Gamma-Ray Burst Exponential Decays Observed with Suzaku WAM

This paper presents a study on the spectral evolution of gamma-ray burst (GRB) prompt emissions observed with the Suzaku Wide-band All-sky Monitor (WAM). By making use of the WAM data archive, 6 bright GRBs exhibiting 7 well-separated fast-rise-exponential-decay (FRED) shaped light curves are presented and the evaluated exponential decay time constants of the energy-resolved light curves from these FRED peak light curves are shown to indicate significant spectral evolution. The energy dependence of the time constants is well described with a power-law function tau(E) ~ E^gamma, where gamma ~ -(0.34 +/- 0.12) in average, although 5 FRED peaks show consistent value of gamma = -1/2 which is expected in synchrotron or inverse-Compton cooling models. In particular, 2 of the GRBs were located with accuracy sufficient to evaluate the time-resolved spectra with precise energy response matrices. Their behavior in spectral evolution suggests two different origins of emissions. In the case of GRB081224, the derived 1-s time-resolved spectra are well described by a blackbody radiation model with a power-law component. The derived behavior of cooling is consistent with that expected from radiative cooling or expansion of the emission region. On the other hand, the other 1-s time-resolved spectra from GRB100707A is well described by a Band GRB model as well as with the thermal model. Although relative poor statistics prevent us to conclude, the energy dependence in decaying light curve is consistent with that expected in the former emission mechanism model.Comment: 11 pages, 7 figures, 5 tables. PASJ accepte

Statistical mechanical analysis of a hierarchical random code ensemble in signal processing

We study a random code ensemble with a hierarchical structure, which is closely related to the generalized random energy model with discrete energy values. Based on this correspondence, we analyze the hierarchical random code ensemble by using the replica method in two situations: lossy data compression and channel coding. For both the situations, the exponents of large deviation analysis characterizing the performance of the ensemble, the distortion rate of lossy data compression and the error exponent of channel coding in Gallager's formalism, are accessible by a generating function of the generalized random energy model. We discuss that the transitions of those exponents observed in the preceding work can be interpreted as phase transitions with respect to the replica number. We also show that the replica symmetry breaking plays an essential role in these transitions.Comment: 24 pages, 4 figure

Ensemble Inequivalence and the Spin-Glass Transition

We report on the ensemble inequivalence in a many-body spin-glass model with integer spin. The spin-glass phase transition is of first order for certain values of the crystal field strength and is dependent whether it was derived in the microcanonical or the canonical ensemble. In the limit of infinitely many-body interactions, the model is the integer-spin equivalent of the random-energy model, and is solved exactly. We also derive the integer-spin equivalent of the de Almeida-Thouless line.Comment: 19 pages, 7 figure