2,102 research outputs found
Raman and fluorescence contributions to resonant inelastic soft x-ray scattering on LaAlO/SrTiO heterostructures
We present a detailed study of the Ti 3 carriers at the interface of
LaAlO/SrTiO heterostructures by high-resolution resonant inelastic soft
x-ray scattering (RIXS), with special focus on the roles of overlayer thickness
and oxygen vacancies. Our measurements show the existence of interfacial Ti
3 electrons already below the critical thickness for conductivity and an
increase of the total interface charge up to a LaAlO overlayer thickness of
6 unit cells before it levels out. By comparing stoichiometric and oxygen
deficient samples we observe strong Ti 3 charge carrier doping by oxygen
vacancies. The RIXS data combined with photoelectron spectroscopy and transport
measurements indicate the simultaneous presence of localized and itinerant
charge carriers. However, it is demonstrated that the relative amount of
localized and itinerant Ti electrons in the ground state cannot be deduced
from the relative intensities of the Raman and fluorescence peaks in excitation
energy dependent RIXS measurements, in contrast to previous interpretations.
Rather, we attribute the observation of either the Raman or the fluorescence
signal to the spatial extension of the intermediate state reached in the RIXS
excitation process.Comment: 9 pages, 6 figure
Natural variation of HIV-1 group M integrase: Implications for a new class of antiretroviral inhibitors
HIV-1 integrase is the third enzymatic target of antiretroviral (ARV) therapy. However, few data have been published on the distribution of naturally occurring amino acid variation in this enzyme. We therefore characterized the distribution of integrase variants among more than 1,800 published group M HIV-1 isolates from more than 1,500 integrase inhibitor (INI)-naïve individuals. Polymorphism rates equal or above 0.5% were found for 34% of the central core domain positions, 42% of the C-terminal domain positions, and 50% of the N-terminal domain positions. Among 727 ARV-naïve individuals in whom the complete pol gene was sequenced, integrase displayed significantly decreased inter- and intra-subtype diversity and a lower Shannon's entropy than protease or RT. All primary INI-resistance mutations with the exception of E157Q – which was present in 1.1% of sequences – were nonpolymorphic. Several accessory INI-resistance mutations including L74M, T97A, V151I, G163R, and S230N were also polymorphic with polymorphism rates ranging between 0.5% to 2.0%
Development of a Conductor with Large Capacity for Fusion Devices by Using Superconducting Tapes with High Aspect Ratio of Cross-section
Development of a Transposed Conductor with Large Capacity Using Superconducting Tapes with High Aspect Ratio of Cross-section
Accretion Properties of A Sample of Hard X-ray (<60keV) Selected Seyfert 1 Galaxies
We examine the accretion properties in a sample of 42 hard (3-60keV) X-ray
selected nearby broad-line AGNs. The energy range in the sample is harder than
that usually used in the similar previous studies. These AGNs are mainly
complied from the RXTE All Sky Survey (XSS), and complemented by the released
INTEGRAL AGN catalog. The black hole masses, bolometric luminosities of AGN,
and Eddington ratios are derived from their optical spectra in terms of the
broad H emission line. The tight correlation between the hard X-ray
(3-20keV) and bolometric/line luminosity is well identified in our sample. Also
identified is a strong inverse Baldwin relationship of the H emission
line. In addition, all these hard X-ray AGNs are biased toward luminous objects
with high Eddington ratio (mostly between 0.01 to 0.1) and low column density
(), which is most likely due to the selection effect
of the surveys. The hard X-ray luminosity is consequently found to be strongly
correlated with the black hole mass. We believe the sample completeness will be
improved in the next few years by the ongoing Swift and INTEGRAL missions, and
by the next advanced missions, such as NuSTAR, Simbol-X, and NeXT. Finally, the
correlation between RFe (=optical FeII/H) and disk temperature as
assessed by leads us to
suggest that the strength of the FeII emission is mainly determined by the
shape of the ionizing spectrum.Comment: 28 pages, 7 figures, 2 tables, accepted by A
CANGAROO-III Search for Gamma Rays from SN 1987A and the Surrounding Field
Optical images of SN 1987A show a triple ring structure. The inner (dust)
ring has recently increased in brightness and in the number of hot spots
suggesting that the supernova shock wave has collided with the dense
pre-existing circumstellar medium, a scenario supported by radio and X-ray
observations. Such a shocked environment is widely expected to result in the
acceleration of charged particles, and the accompanying emission of very high
energy gamma-rays. Here, we report the results of observations made in 2004 and
2006 which yield upper limits on the TeV gamma-ray flux, which are compared
with a theoretical prediction. In addition, we set upper limits on the TeV flux
for four high energy objects which are located within the same field of view of
the observation: the super-bubble 30 Dor C, the Crab-like pulsar PSR
B054069, the X-ray binary LMC X-1, and the supernova remnant N157B.Comment: 5 pages, 5 figures, Accepted for publication in Ap
Searches for very high energy gamma rays from blazars with CANGAROO-III telescope in 2005-2009
We have searched for very high energy (VHE) gamma rays from four blazars
using the CANGAROO-III imaging atmospheric Cherenkov telescope. We report the
results of the observations of H 2356-309, PKS 2155-304, PKS 0537-441, and 3C
279, performed from 2005 to 2009, applying a new analysis to suppress the
effects of the position dependence of Cherenkov images in the field of view. No
significant VHE gamma ray emission was detected from any of the four blazars.
The GeV gamma-ray spectra of these objects were obtained by analyzing Fermi/LAT
archival data. Non-simultaneous wide range (radio to VHE gamma-ray bands)
spectral energy distributions (SEDs) including CANGAROO-III upper limits, GeV
gamma-ray spectra, and archival data are discussed using a one-zone synchrotron
self-Compton (SSC) model in combination with a external Compton (EC) radiation.
The HBLs (H 2356-309 and PKS 2155-304) can be explained by a simple SSC model,
and PKS 0537-441 and 3C 279 are well modeled by a combination of SSC and EC
model. We find a consistency with the blazar sequence in terms of strength of
magnetic field and component size.Comment: 11 pages, 8 figures, Accepted for publication in Astroparticle
Physic
The calibrated population resistance tool: standardized genotypic estimation of transmitted HIV-1 drug resistance
Summary: The calibrated population resistance (CPR) tool is a web-accessible program for performing standardized genotypic estimation of transmitted HIV-1 drug resistance. The program is linked to the Stanford HIV drug resistance database and can additionally perform viral genotyping and algorithmic estimation of resistance to specific antiretroviral drugs
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