87 research outputs found
Characterization of ZrO2-Y2O3 thermal spray powder systems
The overall objective is to establish the interrelation between the raw material in the coating process and the performance of the coating deposit. It is anticipated that these interrelations will help establish more precise specifications for the procurement of the raw materials. Some of the preliminary results of the program are presented
Observations of the SW Sextantis star DW Ursae Majoris with the Far Ultraviolet Spectroscopic Explorer
We present an analysis of the first far-ultraviolet observations of the SW
Sextantis-type cataclysmic variable DW Ursae Majoris, obtained in November 2001
with the Far Ultraviolet Spectroscopic Explorer. The time-averaged spectrum of
DW UMa shows a rich assortment of emission lines (plus some contamination from
interstellar absorption lines including molecular hydrogen). Accretion disk
model spectra do not provide an adequate fit to the far-ultraviolet spectrum of
DW UMa. We constructed a light curve by summing far-ultraviolet spectra
extracted in 60-sec bins; this shows a modulation on the orbital period, with a
maximum near photometric phase 0.93 and a minimum half an orbit later. No other
periodic variability was found in the light curve data. We also extracted
spectra in bins spanning 0.1 in orbital phase; these show substantial variation
in the profile shapes and velocity shifts of the emission lines during an
orbital cycle of DW UMa. Finally, we discuss possible physical models that can
qualitatively account for the observed far-ultraviolet behavior of DW UMa, in
the context of recent observational evidence for the presence of a
self-occulting disk in DW UMa and the possibility that the SW Sex stars may be
the intermediate polars with the highest mass transfer rates and/or weakest
magnetic fields.Comment: accepted by the Astronomical Journal; 36 pages, including 12 figures
and 4 table
Strong spin-orbit interaction and -factor renormalization of hole spins in Ge/Si nanowire quantum dots
The spin-orbit interaction lies at the heart of quantum computation with spin
qubits, research on topologically non-trivial states, and various applications
in spintronics. Hole spins in Ge/Si core/shell nanowires experience a
spin-orbit interaction that has been predicted to be both strong and
electrically tunable, making them a particularly promising platform for
research in these fields. We experimentally determine the strength of
spin-orbit interaction of hole spins confined to a double quantum dot in a
Ge/Si nanowire by measuring spin-mixing transitions inside a regime of
spin-blockaded transport. We find a remarkably short spin-orbit length of
65 nm, comparable to the quantum dot length and the interdot distance. We
additionally observe a large orbital effect of the applied magnetic field on
the hole states, resulting in a large magnetic field dependence of the
spin-mixing transition energies. Strikingly, together with these orbital
effects, the strong spin-orbit interaction causes a significant enhancement of
the -factor with magnetic field.The large spin-orbit interaction strength
demonstrated is consistent with the predicted direct Rashba spin-orbit
interaction in this material system and is expected to enable ultrafast Rabi
oscillations of spin qubits and efficient qubit-qubit interactions, as well as
provide a platform suitable for studying Majorana zero modes
An HST/COS Survey of the Low-Redshift IGM. I. Survey, Methodology, & Overall Results
We use high-quality, medium-resolution {\it Hubble Space Telescope}/Cosmic
Origins Spectrograph (\HST/COS) observations of 82 UV-bright AGN at redshifts
to construct the largest survey of the low-redshift
intergalactic medium (IGM) to date: 5343 individual extragalactic absorption
lines in HI and 25 different metal-ion species grouped into 2610 distinct
redshift systems at covering total redshift pathlengths and . Our semi-automated line-finding and
measurement technique renders the catalog as objectively-defined as possible.
The cumulative column-density distribution of HI systems can be parametrized
, with and
. This distribution is seen to evolve both in amplitude,
, and slope for .
We observe metal lines in 427 systems, and find that the fraction of IGM
absorbers detected in metals is strongly dependent on N_{HI}. The distribution
of OVI absorbers appear to evolve in the same sense as the Lya forest. We
calculate contributions to from different components of the low-
IGM and determine the Lya decrement as a function of redshift. IGM absorbers
are analyzed via a two-point correlation function (TPCF) in velocity space. We
find substantial clustering of \HI\ absorbers on scales of
km/s with no significant clustering at km/s. Splitting the
sample into strong and weak absorbers, we see that most of the clustering
occurs in strong, , metal-bearing IGM systems. The
full catalog of absorption lines and fully-reduced spectra is available via
MAST as a high-level science product at http://archive.stsci.edu/prepds/igm/.Comment: This is the accepted version (v3) of the paper. Previous versions
(July 2015 and Feb. 2014) should be replaced by this one. In particular,
please note that the associated MAST high-level-science product has been
updated to reflect the of the final state of the paper. It is available at:
http://archive.stsci.edu/prepds/igm
Global plagues and the Global Fund: Challenges in the fight against HIV, TB and malaria
BACKGROUND: Although a grossly disproportionate burden of disease from HIV/AIDS, TB and malaria remains in the Global South, these infectious diseases have finally risen to the top of the international agenda in recent years. Ideal strategies for combating these diseases must balance the advantages and disadvantages of 'vertical' disease control programs and 'horizontal' capacity-building approaches. DISCUSSION: The Global Fund to Fight AIDS, Tuberculosis and Malaria (GFATM) represents an important step forward in the struggle against these pathogens. While its goals are laudable, significant barriers persist. Most significant is the pitiful lack of funds committed by world governments, particularly those of the very G8 countries whose discussions gave rise to the Fund. A drastic scaling up of resources is the first clear requirement for the GFATM to live up to the international community's lofty intentions. A directly related issue is that of maintaining a strong commitment to the treatment of the three diseases along with traditional prevention approaches, with the ensuing debates over providing affordable access to medications in the face of the pharmaceutical industry's vigorous protection of patent rights. SUMMARY: At this early point in the Fund's history, it remains to be seen how these issues will be resolved at the programming level. Nevertheless, it is clear that significant structural changes are required in such domains as global spending priorities, debt relief, trade policy, and corporate responsibility. HIV/AIDS, tuberculosis and malaria are global problems borne of gross socioeconomic inequality, and their solutions require correspondingly geopolitical solutions
SDSS-V pioneering panoptic spectroscopy
This white paper presents the case for SDSS-V. SDSS-V is an unprecedented all-sky spectroscopic survey of over six million objects. It is designed to decode the history of the Milky Way galaxy, trace the emergence of the chemical elements, reveal the inner workings of galaxies and their stars, and investigate the origin of planets.Publisher PDFNon peer reviewe
Efeito da densidade populacional sobre desempenho, rendimento de carcaça e qualidade da carne em frangos de corte de diferentes linhagens comerciais
Avaliação de desempenho, rendimento de carcaça e qualidade da carne do peito em frangos de linhagens de conformação versus convencionais
EFFECTS OF SALT REDUCTION ON THE RHEOLOGICAL AND GELATION PROPERTIES OF WHITE AND DARK POULTRY MEAT BATTERS
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