3,582 research outputs found
Recent Developments in Parallelization of the Multidimensional Integration Package DICE
DICE is a general purpose multidimensional numerical integration package.
There can be two ways in the parallelization of DICE, "distributing random
numbers into workers" and "distributing hypercubes into workers". Furthermore,
there can be the combination of both ways. So far, we had developed the
parallelization code using the former way and reported it in ACAT2002 in
Moscow. Here, we will present the recent developments of parallelized DICE in
the latter way as the 2nd stage of our parallelization activities.Comment: 5 pages, 2 figures, Talk given at the X International Workshop on
Advanced Computing and Analysis Techniques in Physics Research, ACAT 2005,
DESY-Zeuthen, Germany, 22-27 May 200
Monte Carlo integration on GPU
We use a graphics processing unit (GPU) for fast computations of Monte Carlo
integrations. Two widely used Monte Carlo integration programs, VEGAS and
BASES, are parallelized on GPU. By using plus multi-gluon production
processes at LHC, we test integrated cross sections and execution time for
programs in FORTRAN and C on CPU and those on GPU. Integrated results agree
with each other within statistical errors. Execution time of programs on GPU
run about 50 times faster than those in C, and more than 60 times faster than
the original FORTRAN programs.Comment: 6 pages, 2 figure
Magnetic effects in heavy-ion collisions at intermediate energies
The time-evolution and space-distribution of internal electromagnetic fields
in heavy-ion reactions at beam energies between 200 and 2000 MeV/nucleon are
studied within an Isospin-dependent Boltzmann-Uhling-Uhlenbeck transport model
IBUU11. While the magnetic field can reach about G which is
significantly higher than the estimated surface magnetic field (
G) of magnetars, it has almost no effect on nucleon observables as the Lorentz
force is normally much weaker than the nuclear force. Very interestingly,
however, the magnetic field generated by the projectile-like (target-like)
spectator has a strong focusing/diverging effect on positive/negative pions at
forward (backward) rapidities. Consequently, the differential
ratio as a function of rapidity is significantly altered by the magnetic field
while the total multiplicities of both positive and negative pions remain about
the same. At beam energies above about 1 GeV/nucleon, while the integrated
ratio of total to multiplicities is not, the differential
ratio is sensitive to the density dependence of nuclear symmetry
energy . Our findings suggest that magnetic effects should
be carefully considered in future studies of using the differential
ratio as a probe of the at supra-saturation
densities.Comment: 12 pages including 8 figures and 1 tabl
Potential Disregard of the Corporate Entity & U.S. Subsidiary Invocation of Japanese Parent\u27s Treaty Rights
U.S. corporate subsidiaries of Japanese parent companies enjoy the same advantages of incorporation (e.g., liability limited to the amount of investment) and the same legal protections extended to domestically-held U.S. corporations (e.g., access to courts and various legal remedies). Thus, it would be a natural and logical assumption that U.S. subsidiaries of Japanese parent companies are required to comply with U.S. law in the same manner as domestically-held corporations. However, some U.S. subsidiaries, by asserting that they are, in reality, inseparable from their Japanese parent companies, have been allowed to avail themselves of exceptions to U.S. law under the U.S.-Japan Friendship, Commerce and Navigation Treaty ( FCN Treaty ). Thus, the paradox arises where Japanese subsidiaries are not required to comply with provisions of the U.S. legal system, but enjoy the same advantages of incorporation and legal protection as domestically-held U.S. corporations. A notable example of such use (or misuse) of the FCN Treaty is the avoidance of liability for discriminatory practices in employment, in particular, wrongful discharge. However, as this Article explains, such use of the FCN Treaty is not without consequence, as the invocation of Treaty rights by a U.S. subsidiary poses the potential danger of disregard of the corporate entity and thus unlimited liability to the Japanese parent company
A massive star origin for an unusual helium-rich supernova in an elliptical galaxy
The unusual helium-rich (type Ib) supernova SN 2005E is distinguished from
any supernova hitherto observed by its faint and rapidly fading light curve,
prominent calcium lines in late-phase spectra and lack of any mark of recent
star formation near the supernova location. These properties are claimed to be
explained by a helium detonation in a thin surface layer of an accreting white
dwarf (Perets et al. 2010). Here we report on observations of SN 2005cz
appeared in an elliptical galaxy, whose observed properties resemble those of
SN 2005E in that it is helium-rich and unusually faint, fades rapidly, shows
much weaker oxygen emission lines than those of calcium in the well-evolved
spectrum. We argue that these properties are best explained by a core-collapse
supernova at the low-mass end () of the range of massive stars
that explode (Smartt 2009). Such a low mass progenitor had lost its
hydrogen-rich envelope through binary interaction, having very thin oxygen-rich
and silicon-rich layers above the collapsing core, thus ejecting a very small
amount of radioactive Ni and oxygen. Although the host galaxy NGC 4589
is an elliptical, some studies have revealed evidence of recent star-formation
activity (Zhang et al. 2008), consistent with the core-collapse scenario.Comment: Accepted by Nature (24 March 2010), 32 pages including Supplementary
Informatio
Spin-charge mixing effects on resonant tunneling in a polarized Luttinger Liquid
We investigate spin-charge mixing effect on resonant tunneling in
spin-polarized Tomonaga-Luttinger liquid with double impurities. The mixing
arises from Fermi velocity difference between two spin species due to Zeeman
effect. Zero bias conductance is calculated as a function of gate voltage
, gate magnetic field , temperature and magnetic field
applied to the system. Mixing effect is shown to cause rotation of the lattice
pattern of the conductance peaks in plane, which can be
observed in experiments. At low temperatures, the contour shapes are classified
into three types, reflecting the fact that effective barrier potential is
renormalized towards ``perfect reflection'', ``perfect transmission'' and
magnetic field induced ``spin-filtering'', respectively.Comment: 10 pages, 4 figures, Sec.I and references largely changed, results
for a strong barrier limit added in a new section Sec.I
The Unique Type Ib Supernova 2005bf at Nebular Phases: A Possible Birth Event of A Strongly Magnetized Neutron Star
Late phase nebular spectra and photometry of Type Ib Supernova (SN) 2005bf
taken by the Subaru telescope at ~ 270 and ~ 310 days since the explosion are
presented. Emission lines ([OI]6300, 6363, [CaII]7291, 7324, [FeII]7155) show
the blueshift of ~ 1,500 - 2,000 km s-1. The [OI] doublet shows a doubly-peaked
profile. The line luminosities can be interpreted as coming from a blob or jet
containing only ~ 0.1 - 0.4 Msun, in which ~ 0.02 - 0.06 Msun is 56Ni
synthesized at the explosion. To explain the blueshift, the blob should either
be of unipolar moving at the center-of-mass velocity v ~ 2,000 - 5,000 km s-1,
or suffer from self-absorption within the ejecta as seen in SN 1990I. In both
interpretations, the low-mass blob component dominates the optical output both
at the first peak (~ 20 days) and at the late phase (~ 300 days). The low
luminosity at the late phase (the absolute R magnitude M_R ~ -10.2 mag at ~ 270
days) sets the upper limit for the mass of 56Ni < ~ 0.08 Msun, which is in
contradiction to the value necessary to explain the second, main peak
luminosity (M_R ~ -18.3 mag at ~ 40 days). Encountered by this difficulty in
the 56Ni heating model, we suggest an alternative scenario in which the heating
source is a newly born, strongly magnetized neutron star (a magnetar) with the
surface magnetic field Bmag ~ 10^{14-15} gauss and the initial spin period P0 ~
10 ms. Then, SN 2005bf could be a link between normal SNe Ib/c and an X-Ray
Flash associated SN 2006aj, connected in terms of Bmag and/or P0.Comment: 16 pages, 12 figures. Accepted by the Astrophysical Journa
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