1,214 research outputs found
On the Origin of the -4.4 eV Band in CdTe(100)"
We calculate the bulk- (infinite system), (100)-bulk-projected- and
(100)-Surface-projected Green's functions using the Surface Green's Function
Matching method (SGFM) and an empirical tight-binding hamiltonian with
tight-binding parameters (TBP) that describe well the bulk band structure of
CdTe. In particular, we analyze the band (B--4) arising at --4.4 eV from the
top of the valence band at according to the results of Niles and
H\"ochst and at -4.6 eV according to Gawlik {\it et al.} both obtained by
Angle-resolved photoelectron spectroscopy (ARPES). We give the first
theoretical description of this band.Comment: 17 pages, Rev-TEX, CIEA-Phys. 02/9
Efficient state-based CRDTs by delta-mutation
CRDTs are distributed data types that make eventual consistency of a distributed object possible and non ad-hoc. Specifically, state-based CRDTs ensure convergence through disseminating the entire state, that may be large, and merging it to other replicas; whereas operation-based CRDTs disseminate operations (i.e., small states) assuming an exactly-once reliable dissemination layer. We introduce Delta State Conflict-Free Replicated Datatypes (δ-CRDT) that can achieve the best of both worlds: small messages with an incremental nature, disseminated over unreliable communication channels. This is achieved by defining δ-mutators to return a delta-state, typically with a much smaller size than the full state, that is joined to both: local and remote states. We introduce the δ-CRDT framework, and we explain it through establishing a correspondence to current state-based CRDTs. In addition, we present an anti-entropy algorithm that ensures causal consistency, and two δ-CRDT specifications of well-known replicated datatypes.This work is co-financed by the North Portugal Regional Operational Programme (ON.2, O Novo Norte), under the National Strategic Reference Framework (NSRF), through the European Regional Development Fund (ERDF), within project NORTE07-0124-FEDER-000058; and by EU FP7 SyncFree project (609551)
Perioperative care of the geriatric patient for noncardiac surgery
Adults age 65 and over are the fastest growing segment of the population in the United States and around the world. As the size of this population expands, the number of older adults referred for surgical procedures will continue to increase. Due to the physiologic changes of aging and the increased frequency of comorbidities, older adults are at increased risk for adverse outcomes, and perioperative care is inherently more complex than in younger individuals. In this review, we discuss the physiologic changes of aging relevant to the surgical patient, comprehensive preoperative assessment, and postoperative management of common complications in older adults in order to promote optimal clinical outcomes both perioperatively and long-term
Plasma membrane localization and fusion inhibitory activity of the cowpox virus serpin SPI-3 require a functional signal sequence and the virus encoded hemagglutinin
AbstractThe cowpox virus (CPV) glycoprotein serpin SPI-3, a functional protease inhibitor, and the viral hemagglutinin (HA) are required to prevent fusion of wt CPV infected cells. SPI-3 and HA from CPV infected cells co-localize to the plasma membrane and are found in extracellular enveloped virus (EEV). We also show that an N-terminal SPI-3 signal sequence, but not glycosylation, is required for membrane localization and fusion inhibition. In the absence of HA (CPVÎHA), no SPI-3 is found on the membrane and infected cells fuse. Conversely, HA from both wt CPV and CPVÎSPI-3 infections is on the membrane, indicating a requirement of HA for SPI-3 plasma membrane localization. In the absence of HA, secretion of SPI-3 or SPI-3 N-glyc(â) was markedly enhanced, suggesting HA serves to retain SPI-3 on the plasma membrane,thereby preventing cell fusion
The wideband backend at the MDSCC in Robledo. A new facility for radio astronomy at Q- and K- bands
The antennas of NASA's Madrid Deep Space Communications Complex (MDSCC) in
Robledo de Chavela are available as single-dish radio astronomical facilities
during a significant percentage of their operational time. Current
instrumentation includes two antennas of 70 and 34 m in diameter, equipped with
dual-polarization receivers in K (18 - 26 GHz) and Q (38 - 50 GHz) bands,
respectively. We have developed and built a new wideband backend for the
Robledo antennas, with the objectives (1) to optimize the available time and
enhance the efficiency of radio astronomy in MDSCC; and (2) to tackle new
scientific cases impossible to that were investigated with the old, narrow-band
autocorrelator. The backend consists of an IF processor, a FFT spectrometer
(FFTS), and the software that interfaces and manages the events among the
observing program, antenna control, the IF processor, the FFTS operation, and
data recording. The whole system was end-to-end assembled in August 2011, at
the start of commissioning activities, and the results are reported in this
paper. Frequency tunings and line intensities are stable over hours, even when
using different synthesizers and IF channels; no aliasing effects have been
measured, and the rejection of the image sideband was characterized. The first
setup provides 1.5 GHz of instantaneous bandwidth in a single polarization,
using 8192 channels and a frequency resolution of 212 kHz; upgrades under way
include a second FFTS card, and two high-resolution cores providing 100 MHz and
500 MHz of bandwidth, and 16384 channels. These upgrades will permit
simultaneous observations of the two polarizations with instantaneous
bandwidths from 100 MHz to 3 GHz, and spectral resolutions from 7 to 212 kHz.Comment: 9 pages, 8 figures. Accepted to Astronomy and Astrophysic
Making Operation-based CRDTs Operation-based
Conflict-free Replicated Datatypes can simplify the design of predictable eventual consistency. They can be classified into state-based or operation-based. Operation-based approaches have the potential for allowing compact designs in both the sent message and the object state size, but cur- rent approaches are still far from this objective. Here we explore the design space for operation-based solutions, and we leverage the interaction with the middleware by offering a technique that delivers very compact solutions, while only broadcasting operation names and arguments.(undefined)(undefined
Alpha Antihydrogen Experiment
ALPHA is an experiment at CERN, whose ultimate goal is to perform a precise
test of CPT symmetry with trapped antihydrogen atoms. After reviewing the
motivations, we discuss our recent progress toward the initial goal of stable
trapping of antihydrogen, with some emphasis on particle detection techniques.Comment: Invited talk presented at the Fifth Meeting on CPT and Lorentz
Symmetry, Bloomington, Indiana, June 28-July 2, 201
Antihydrogen and mirror-trapped antiproton discrimination: Discriminating between antihydrogen and mirror-trapped antiprotons in a minimum-B trap
Recently, antihydrogen atoms were trapped at CERN in a magnetic minimum
(minimum-B) trap formed by superconducting octupole and mirror magnet coils.
The trapped antiatoms were detected by rapidly turning off these magnets,
thereby eliminating the magnetic minimum and releasing any antiatoms contained
in the trap. Once released, these antiatoms quickly hit the trap wall,
whereupon the positrons and antiprotons in the antiatoms annihilated. The
antiproton annihilations produce easily detected signals; we used these signals
to prove that we trapped antihydrogen. However, our technique could be
confounded by mirror-trapped antiprotons, which would produce
seemingly-identical annihilation signals upon hitting the trap wall. In this
paper, we discuss possible sources of mirror-trapped antiprotons and show that
antihydrogen and antiprotons can be readily distinguished, often with the aid
of applied electric fields, by analyzing the annihilation locations and times.
We further discuss the general properties of antiproton and antihydrogen
trajectories in this magnetic geometry, and reconstruct the antihydrogen energy
distribution from the measured annihilation time history.Comment: 17 figure
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