13,385 research outputs found
Manufacture and evaluation of Li/BCX DD cells
This project is divided into four main tasks: cell manufacture, acceptance, and lot certification of cells, performance testing of cells, and abuse testing of cells. Lithium/bromine chloride in thionyl chloride (Li/BCX) 149 DD cells (PN 3B2085-XA) were built according to the provisions of Electrochem Industries Quality Plan 17096. Acceptance and lot certification testing was performed according to NASA JSC Document EP5-83-025, Revision B. Acceptance testing included open circuit and load voltage check, visual examination, size and weight measurements, and high temperature exposure. Lot certification tests were performed for capacity performance and for performance under conditions of thermal and electrical abuse. These tests included 149 C exposure, capacity discharge, fuse check, high temperature exposure, high rate discharge, short circuit, vibration, and overdischarge testing. A quantity of 200 cells was delivered to Johnson Space Center for life test evaluation. A parametric evaluation of the capacity discharge of Li/BCX DD cells was performed over a variety of temperatures and discharge rates. This testing served to map the performance capability of the cell. Tests were also performed over a variety of electrical and thermal abuse conditions. Abuse tests included short circuit, charging, overdischarge, high temperature exposure, shock, and vibration
Quantum phase gate for photonic qubits using only beam splitters and post-selection
We show that a beam splitter of reflectivity one-third can be used to realize
a quantum phase gate operation if only the outputs conserving the number of
photons on each side are post-selected.Comment: 6 pages RevTex, including one figur
Far-Ultraviolet and Far-Infrared Bivariate Luminosity Function of Galaxies: Complex Relation between Stellar and Dust Emission
Far-ultraviolet (FUV) and far-infrared (FIR) luminosity functions (LFs) of
galaxies show a strong evolution from to , but the FIR LF
evolves much stronger than the FUV one. The FUV is dominantly radiated from
newly formed short-lived OB stars, while the FIR is emitted by dust grains
heated by the FUV radiation field. It is known that dust is always associated
with star formation activity. Thus, both FUV and FIR are tightly related to the
star formation in galaxies, but in a very complicated manner. In order to
disentangle the relation between FUV and FIR emissions, we estimate the UV-IR
bivariate LF (BLF) of galaxies with {\sl GALEX} and {\sl AKARI} All-Sky Survey
datasets. Recently we invented a new mathematical method to construct the BLF
with given marginals and prescribed correlation coefficient. This method makes
use of a tool from mathematical statistics, so called "copula". The copula
enables us to construct a bivariate distribution function from given marginal
distributions with prescribed correlation and/or dependence structure. With
this new formulation and FUV and FIR univariate LFs, we analyze various FUV and
FIR data with {\sl GALEX}, {\sl Spitzer}, and {\sl AKARI} to estimate the UV-IR
BLF. The obtained BLFs naturally explain the nonlinear complicated relation
between FUV and FIR emission from star-forming galaxies. Though the faint-end
of the BLF was not well constrained for high- samples, the estimated linear
correlation coefficient was found to be very high, and is remarkably
stable with redshifts (from 0.95 at to 0.85 at ). This implies
the evolution of the UV-IR BLF is mainly due to the different evolution of the
univariate LFs, and may not be controlled by the dependence structure.Comment: 10 pages, 7 figures, Earth, Planets and Space, in pres
Star formation and dust extinction properties of local galaxies from AKARI-GALEX All-Sky Surveys: First results from most secure multiband sample from FUV to FIR
The AKARI All-Sky Survey provided the first bright point source catalog
detected at 90um. Starting from this catalog, we selected galaxies by matching
AKARI sources with those in the IRAS PSCz. Next, we have measured total GALEX
FUV and NUV flux densities. Then, we have matched this sample with SDSS and
2MASS galaxies. By this procedure, we obtained the final sample which consists
of 607 galaxies. If we sort the sample with respect to 90um, their average SED
shows a coherent trend: the more luminous at 90um, the redder the global SED
becomes. The M_r--NUV-r color-magnitude relation of our sample does not show
bimodality, and the distribution is centered on the green valley between the
blue cloud and red sequence seen in optical surveys. We have established
formulae to convert FIR luminosity from AKARI bands to the total infrared (IR)
luminosity L_TIR. With these formulae, we calculated the star formation
directly visible with FUV and hidden by dust. The luminosity related to star
formation activity (L_SF) is dominated by L_TIR even if we take into account
the far-infrared (FIR) emission from dust heated by old stars. At high star
formation rate (SFR) (> 20 Msun yr^-1), the fraction of directly visible SFR,
SFR_FUV, decreases. We also estimated the FUV attenuation A_FUV from
FUV-to-total IR (TIR) luminosity ratio. We also examined the L_TIR/L_FUV-UV
slope (FUV- NUV) relation. The majority of the sample has L_TIR/L_FUV ratios 5
to 10 times lower than expected from the local starburst relation, while some
LIRGs and all the ULIRGs of this sample have higher L_TIR/L_FUV ratios. We
found that the attenuation indicator L_TIR/L_FUV is correlated to the stellar
mass of galaxies, M*, but there is no correlation with specific SFR (SSFR),
SFR/M*, and dust attenuation L_TIR/L_FUV. (abridged)Comment: 13 pages, 18 figures, accepted for publication in A&
CP, T and CPT Violations in the K^0 - bar{K^0} System -- Present Status --
Possible violation of CP, T and CPT symmetries in the K^0 - bar{K^0} system
is studied in a way as phenomenological and comprehensive as possible. For this
purpose, we first introduce parameters which represent violation of these
symmetries in mixing parameters and decay amplitudes in a convenient and
well-defined way and, treating these parameters as small, derive formulas which
relate them to the experimentally measured quantities. We then perform
numerical analyses to derive constraints to these symmetry-violating
parameters, with the latest data reported by KTeV Collaboration, NA48
Collaboration and CPLEAR Collaboration, along with those compiled by Particle
Data Group, used as inputs. The result obtained by CPLEAR Collaboration from an
unconstrained fit to a time-dependent leptonic asymmetry, aided by the
Bell-Steinberger relation, enables us to determine or constrain most of the
parameters separately. It is shown among the other things that (1) CP and T
symmetries are violated definitively at least at the level of 10^{-4} in 2 pi
decays, (2) CP and T symmetries are violated at least at the level of 10^{-3}
in the K^0 - bar{K^0} mixing, and (3) CPT symmetry is at present tested to the
level of 10^{-5} at the utmost.Comment: 20 page
The infrared emission of ultraviolet selected galaxies from z = 0 to z=1
We select galaxies in UV rest-frame at z=0, z~0.7 and z~1 together with a
sample of LBGs at z~1, the samples are built in order to sample the same range
of luminosity at any redshift. The evolution of the IR and UV luminosities with
z is analysed for individual galaxies as well as in terms of luminosity
functions. The L_IR/L_UV ratio is used to measure dust attenuation. This ratio
does not exhibit a strong evolution with z for the bulk of our sample galaxies
but some trends are found for galaxies with a strong dust attenuation and for
UV luminous sources: galaxies with L_IR/L_UV>10 are more frequent at z>0 than
at z=0 and the largest values of L_IR/L_UV are found for UV faint objects;
conversely the most luminous galaxies of our samples (L_UV> 2 10^{10} L_sun$),
detected at z=1, exhibit a lower dust attenuation than the fainter ones.
L_IR/L_UV increases with the K rest-frame luminosity of the galaxies at all the
redshifts considered and shows a residual anti-correlation with L_UV. The most
massive and UV luminous galaxies exhibit quite large specific star formation
rates. LBGs exhibit systematically lower dust attenuation than UV selected
galaxies of same luminosity but similar specific star formation rates. The
analysis of the UV+IR luminosity functions leads to the conclusion that up to z
= 1 most of the star formation activity of UV selected galaxies is emitted in
IR. Whereas we are able to retrieve all the star formation from our UV
selection at z=0.7, at z = 1 we miss a large fraction of galaxies more luminous
than ~ 10^{11} L_sun. The effect is found larger for Lyman Break Galaxies.Comment: 13 pages. accepted for publication (Astronomy and Astrophysics
Schwarzschild radius from Monte Carlo calculation of the Wilson loop in supersymmetric matrix quantum mechanics
In the string/gauge duality it is important to understand how the space-time
geometry is encoded in gauge theory observables. We address this issue in the
case of the D0-brane system at finite temperature T. Based on the duality, the
temporal Wilson loop operator W in gauge theory is expected to contain the
information of the Schwarzschild radius R_{Sch} of the dual black hole geometry
as log = R_{Sch} / (2 pi alpha' T). This translates to the power-law
behavior log = 1.89 (T/lambda^{1/3})^{-3/5}, where lambda is the 't Hooft
coupling constant. We calculate the Wilson loop on the gauge theory side in the
strongly coupled regime by performing Monte Carlo simulation of supersymmetric
matrix quantum mechanics with 16 supercharges. The results reproduce the
expected power-law behavior up to a constant shift, which is explainable as
alpha' corrections on the gravity side.Comment: REVTeX4, 4 pages, 1 figur
Quantum filter for non-local polarization properties of photonic qubits
We present an optical filter that transmits photon pairs only if they share
the same horizontal or vertical polarization, without decreasing the quantum
coherence between these two possibilities. Various applications for
entanglement manipulations and multi-photon qubits are discussed.Comment: 7 pages, including one figure, short discussion of error sources
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Diffusive versus local spin currents in dynamic spin pumping systems
Using microscopic theory, we investigate the properties of a spin current
driven by magnetization dynamics. In the limit of smooth magnetization texture,
the dominant spin current induced by the spin pumping effect is shown to be the
diffusive spin current, i.e., the one arising from only a diffusion associated
with spin accumulation. That is to say, there is no effective field that
locally drives the spin current. We also investigate the conversion mechanism
of the pumped spin current into a charge current by spin-orbit interactions,
specifically the inverse spin Hall effect. We show that the spin-charge
conversion does not always occur and that it depends strongly on the type of
spin-orbit interaction. In a Rashba spin-orbit system, the local part of the
charge current is proportional to the spin relaxation torque, and the local
spin current, which does not arise from the spin accumulation, does not play
any role in the conversion. In contrast, the diffusive spin current contributes
to the diffusive charge current. Alternatively, for spin-orbit interactions
arising from random impurities, the local charge current is proportional to the
local spin current that constitutes only a small fraction of the total spin
current. Clearly, the dominant spin current (diffusive spin current) is not
converted into a charge current. Therefore, the nature of the spin current is
fundamentally different depending on its origin and thus the spin transport and
the spin-charge conversion behavior need to be discussed together along with
spin current generation
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