6,215 research outputs found
Prompt GeV-TeV Emission of Gamma-Ray Bursts Due to High-Energy Protons, Muons and Electron-Positron Pairs
In the framework of the internal shock scenario, we model the broadband
prompt emission of gamma-ray bursts (GRBs) with emphasis on the GeV-TeV bands,
utilizing Monte Carlo simulations that include various processes associated
with electrons and protons accelerated to high energies. While inverse Compton
emission from primary electrons is often dominant, different proton-induced
mechanisms can also give rise to distinct high-energy components, such as
synchrotron emission from protons, muons or secondary electrons/positrons
injected via photomeson interactions. In some cases, they give rise to double
spectral breaks that can serve as unique signatures of ultra-high-energy
protons. We discuss the conditions favorable for such emission, and how they
are related to the production of ultra-high-energy cosmic rays and neutrinos in
internal shocks. Ongoing and upcoming observations by {\it GLAST}, atmospheric
Cerenkov telescopes and other facilities will test these expectations and
provide important information on the physical conditions in GRB outflows.Comment: 11 pages, 8 figures and 14 appendix figures, accepted for publication
in ApJ vol. 671 with minor revision
Gamma Ray Bursts: recent results and connections to very high energy Cosmic Rays and Neutrinos
Gamma-ray bursts are the most concentrated explosions in the Universe. They
have been detected electromagnetically at energies up to tens of GeV, and it is
suspected that they could be active at least up to TeV energies. It is also
speculated that they could emit cosmic rays and neutrinos at energies reaching
up to the eV range. Here we review the recent developments in
the photon phenomenology in the light of \swift and \fermi satellite
observations, as well as recent IceCube upper limits on their neutrino
luminosity. We discuss some of the theoretical models developed to explain
these observations and their possible contribution to a very high energy cosmic
ray and neutrino background.Comment: 12 pages, 7 figures. Text of a plenary lecture at the PASCOS 12
conference, Merida, Yucatan, Mexico, June 2012; to appear in J.Phys. (Conf.
Series
Effect of the Vortices on the Nuclear Spin Relaxation Rate in the Unconventional Pairing States of the Organic Superconductor (TMTSF)PF
This Letter theoretically discusses quasiparticle states and nuclear spin
relaxation rates in a quasi-one-dimensional superconductor
(TMTSF)PF under a magnetic field applied parallel to the conduction
chains. We study the effects of Josephson-type vortices on by
solving the Bogoliubov de Gennes equation for -, - or -wave pairing
interactions. In the presence of line nodes in pairing functions, is
proportional to in sufficiently low temperatures because quasiparticles
induced by vortices at the Fermi energy relax spins. We also try to identify
the pairing symmetry of (TMTSF)PF.Comment: 4+ pages, 4 figure
Tenth-order lepton g-2: Contribution from diagrams containing a sixth-order light-by-light-scattering subdiagram internally
This paper reports the result of our evaluation of the tenth-order QED
correction to the lepton g-2 from Feynman diagrams which have sixth-order
light-by-light-scattering subdiagrams, none of whose vertices couple to the
external magnetic field. The gauge-invariant set of these diagrams, called Set
II(e), consists of 180 vertex diagrams. In the case of the electron g-2 (a_e),
where the light-by-light subdiagram consists of the electron loop, the
contribution to a_e is found to be - 1.344 9 (10) (\alpha /\pi)^5. The
contribution of the muon loop to a_e is - 0.000 465 (4) (\alpha /\pi)^5. The
contribution of the tau-lepton loop is about two orders of magnitudes smaller
than that of the muon loop and hence negligible. The sum of all of these
contributions to a_e is - 1.345 (1) (\alpha /\pi)^5. We have also evaluated the
contribution of Set II(e) to the muon g-2 (a_\mu). The contribution to a_\mu
from the electron loop is 3.265 (12) (\alpha /\pi)^5, while the contribution of
the tau-lepton loop is -0.038 06 (13) (\alpha /\pi)^5. The total contribution
to a_\mu, which is the sum of these two contributions and the mass-independent
part of a_e, is 1.882 (13) (\alpha /\pi)^5.Comment: 18 pages, 3 figures, REVTeX4, axodraw.sty used, changed title,
corrected uncertainty of a_mu, added a referenc
Josephson effect in quasi one-dimensional unconventional superconductors
Josephson effect in junctions of quasi one-dimensional triangular lattice
superconductors is discussed, where the theoretical model corresponds to
organic superconductors (TMTSF)_2PF_6. We assume the quarter-filling electron
band and p, d and f wave like pairing symmetries in organic superconductors. To
realize the electronic structures in organic superconductors, we introduce the
asymmetric hopping integral, (t') among second nearest lattice sites. At t'=0,
the Josephson current in the d wave symmetry saturates in low temperatures,
whereas those in the p and the f wave symmetries show the low-temperature
anomaly due to the zero-energy state at the junction interfaces. The
low-temperature anomaly appears even in the d wave symmetry in the presence of
t', whereas the anomaly is suppressed in the f wave symmetry. The shape of the
Fermi surface is an important factor for the formation of the ZES in the
quarter-filling electron systems.Comment: 10 page
Suppressive activity of a macrolide antibiotic, roxithromycin on co-stimulatory molecule expression on mouse splenocytes in vivo.
The influence of roxithromycin (RXM) on the expression of co-stimulatory molecules, CD40, CD80 and CD86, was examined in vivo. When BALB/c mice were immunized intraperitoneally with two doses of dinitrophenylated ovalbumin (DNP-OVA) at 1 week intervals, intraperitoneal administration of RXM at 250 microg/kg once a day for 14 days strongly suppressed IgE contents in sera obtained from mice 22 days after the first immunization. In addition, RXM treatment of mice suppressed endogenous IL-4 contents in aqueous spleen extracts, which were enhanced by DNP-OVA immunization. We next examined the influence of RXM on co-stimulatory molecule expression on splenic lymphocytes. RXM treatment of the immunized mice caused suppression of CD40 expression, but this treatment did not affect CD80 and CD86 expression
A phenomenological theory of zero-energy Andreev resonant states
A conceptual consideration is given to a zero-energy state (ZES) at the
surface of unconventional superconductors. The reflection coefficients in
normal-metal / superconductor (NS) junctions are calculated based on a
phenomenological description of the reflection processes of a quasiparticle.
The phenomenological theory reveals the importance of the sign change in the
pair potential for the formation of the ZES. The ZES is observed as the
zero-bias conductance peak (ZBCP) in the differential conductance of NS
junctions. The split of the ZBCP due to broken time-reversal symmetry states is
naturally understood in the present theory. We also discuss effects of external
magnetic fields on the ZBCP.Comment: 12 page
Suppressive effects of anti-allergic agent suplatast tosilate (IPD-1151T) on the expression of co-stimulatory molecules on mouse splenocytes in vivo.
The effects of IPD-1151T on the expression of co-stimulatory molecules, CD40, CD80 and CD86, were investigated in vivo using mice with allergic disorders. BALB/c mice were immunized intraperitoneally with two doses of dinitrophenylated ovalbumin (DNP-OVA) at 1-week intervals. These mice then were treated intraperitoneally with 100 microg/kg of IPD-1151T once a day for 14 days, starting 7 days after the first immunization. On day 21, some mice were challenged intraperitoneally with DNP-OVA and the other mice were not challenged. All mice were autopsied on day 22 and assayed for immunoglobulin E, interleuken (IL)-4 and IL-5 productions following DNP-OVA immunization. The intraperitoneal treatment with IPD-1151T strongly suppressed immunoglobulin E contents in serum, which were enhanced by DNA-OVA immunization. IPD-1151T also caused a decrease in both IL-4 and IL-5 levels in splenic lymphocytes. We next examined the influence of IPD-1151T on co-stimulatory molecule expression on splenic lymphocytes. IPD-1151T caused suppression of CD40 and CD86 expression; however, the treatments did not affect CD80 expression
Inhibitory effect of interferon-beta on mouse spleen-derived mast cells
Preparations of murine recombinant interferon (Mu-rIFN)-alpha, -beta and -gamma were assessed for their influence on in vitro growth of mast cells from normal mouse spleen cells (Sp C). Mast cell growth was inhibited by Mu-rIFNs when Sp C were exposed throughout the entire culture period to Mu-rIFNs. The most potent inhibitor of mast cell growth was Mu-rIFN-γ, followed by Mu-rIFN-β; Mu-rlFN-α had little effect. When added to IC-2 cells, clonal mast cell progenitor, both Mu-rlFN-β and −γ), significantly inhibited proliferative response of the target cells. The suppressive effect of Mu-rIFNs on IC-2 cells was selectively abolished by monoclonal antibodies against Mu-rIFN-β and −γ
A Static Optimality Transformation with Applications to Planar Point Location
Over the last decade, there have been several data structures that, given a
planar subdivision and a probability distribution over the plane, provide a way
for answering point location queries that is fine-tuned for the distribution.
All these methods suffer from the requirement that the query distribution must
be known in advance.
We present a new data structure for point location queries in planar
triangulations. Our structure is asymptotically as fast as the optimal
structures, but it requires no prior information about the queries. This is a
2D analogue of the jump from Knuth's optimum binary search trees (discovered in
1971) to the splay trees of Sleator and Tarjan in 1985. While the former need
to know the query distribution, the latter are statically optimal. This means
that we can adapt to the query sequence and achieve the same asymptotic
performance as an optimum static structure, without needing any additional
information.Comment: 13 pages, 1 figure, a preliminary version appeared at SoCG 201
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