59,848 research outputs found
The SA-2239/WLQ-4(V) Cutty Sark distribution system
A redundant frequency and time distribution system provides a multiplicity of isolated outputs, all of which are derived from three atomic frequency standards. The distribution system monitors input parameters of the signals coming from the Cesium Standards and selects one to be the primary standard, phase locks an internal oscillator which has excellent aging characteristics in the open loop mode and acts as a filter to provide phase noise improvement, and generates 1 megahertz and 100 kHz by direct synthesis. Additionally, the system distributes RF and timing signals consisting of 5 MHz, 1 MHz, 100 kHz, BCD Time-of-Day, 1 pps and 1 ppm
Spin-glass-like state in GdCu: role of phase separation and magnetic frustration
We report investigations on the ground state magnetic properties of
intermetallic compound GdCu through dc magnetization measurements. GdCu
undergoes first order martensitic type structural transition over a wide
temperature window of coexisting phases. The high temperature cubic and the low
temperature orthorhombic phases have different magnetic character and they show
antiferromagnetic and helimagnetic orderings below 145 K and 45 K respectively.
We observe clear signature of a glassy magnetic phase below the helimagnetic
ordering temperature, which is marked by thermomagnetic irreversibility, aging
and memory effects. The glassy magnetic phase in GdCu is found to be rather
intriguing with its origin lies in the interfacial frustration due to distinct
magnetic character of the coexisting phases.Comment: Physical Review B 83, 134427 (2011
Intermediate-mass Black Holes in Galactic Nuclei
We present the first homogeneous sample of intermediate-mass black hole
candidates in active galactic nuclei. Starting with broad-line active nuclei
from the Sloan Digital Sky Survey, we use the linewidth-luminosity-mass scaling
relation to select a sample of 19 galaxies in the mass range M_BH ~ 8 x 10^4 -
10^6 solar masses. In contrast to the local active galaxy population, the host
galaxies are ~1 mag fainter than M* and thus are probably late-type systems.
The active nuclei are also faint, with M_g ~ -15 to -18 mag, while the
bolometric luminosities are close to the Eddington limit. The spectral
properties of the sample are compared to the related class of objects known as
narrow-line Seyfert 1 galaxies. We discuss the importance of our sample as
observational analogues of primordial black holes, contributors to the
integrated signal for future gravitational wave experiments, and as a valuable
tool in the calibration of the M-sigma relation.Comment: 4 pages, 4 figures. To appear in "The Interplay among Black Holes,
Stars and ISM in Galactic Nuclei," Proc. IAU 222 (Gramado, Brazil), eds Th.
Storchi Bergmann, L.C. Ho, H.R. Schmit
Momentum Analysis in Strong-field Double Ionization
We provide a basis for the laser intensity dependence of the momentum
distributions of electrons and ions arising from strong-field non-sequential
double ionization (NSDI) at intensities in the range . To do this we use a completely classical method introduced previously
\cite{ho-etal05}. Our calculated results reproduce the features of experimental
observations at different laser intensities and depend on just two distinct
categories of electon trajectories.Comment: 5 pages, 7 figure
Risk factors for failure of outpatient parenteral antibiotic therapy (OPAT) in infective endocarditis
Objectives:
To identify risk factors for failure of outpatient antibiotic therapy (OPAT) in infective endocarditis (IE).
Patients and methods:
We identified IE cases managed at a single centre over 12 years from a prospectively maintained database. ‘OPAT failure’ was defined as unplanned readmission or antibiotic switch due to adverse drug reaction or antibiotic resistance. We analysed patient and disease-related risk factors for OPAT failure by univariate and multivariate logistic regression. We also retrospectively collected follow-up data on adverse disease outcome (defined as IE-related death or relapse) and performed Kaplan–Meier survival analysis up to 36 months following OPAT.
Results:
We identified 80 episodes of OPAT in IE. Failure occurred in 25/80 episodes (31.3%). On multivariate analysis, cardiac or renal failure [pooled OR 7.39 (95% CI 1.84–29.66), P = 0.005] and teicoplanin therapy [OR 8.69 (95% CI 2.01–37.47), P = 0.004] were independently associated with increased OPAT failure. OPAT failure with teicoplanin occurred despite therapeutic plasma levels. OPAT failure predicted adverse disease outcome up to 36 months (P = 0.016 log-rank test).
Conclusions:
These data caution against selecting patients with endocarditis for OPAT in the presence of cardiac or renal failure and suggest teicoplanin therapy may be associated with suboptimal OPAT outcomes. Alternative regimens to teicoplanin in the OPAT setting should be further investigated
Nondestructive measurement of capillary tube internal diameter
Technique provides nondestructive method of making quick, accurate determination by measuring electrical resistance of capillary tube when it is filled with electrolyte of known conductivity. Apparatus consists of conductivity cell and equipment for measuring resistance and for monitoring and controlling temperature
Effect of disorder on a Pomeranchuk instability
We study the effect of disorder on the order parameter equation and
transition temperature of a Pomeranchuk-type Fermi-surface instability using
replica mean field theory. We consider the example of a phase transition to a
type Fermi surface distortion, and show that, in the regime
where such a transition is second order, the transition temperature is reduced
by disorder in essentially the same way as that for a d-wave superconductor. We
argue that observing this disorder dependence of metal-to-metal transition
might be a useful indicator of a finite angular momentum Fermi surface
distortion.Comment: 4.1 pages, 3 figs. Version as published in EPL. Added data of
Sr3Ru2O7 to theory curves of Fig.2, and some clarification of derivation of
result
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