14,284 research outputs found
Antechamber facilitates loading and unloading of vacuum furnace
Antechamber facilitates the use of a furnace in which materials are heat treated in a high vacuum or a gas atmosphere. It has a high vacuum pumping system, a means for backfilling with a selected gas, an access door, glove ports, and a motor driven platform
Strongly Enhanced Hole-Phonon Coupling in the Metallic State of the Dilute Two-Dimensional Hole Gas
We have studied the temperature dependent phonon emission rate () of a
strongly interacting (22) dilute 2D GaAs hole system using a standard
carrier heating technique. In the still poorly understood metallic state, we
observe that () changes from () to ()
above 100mK, indicating a crossover from screened piezoelectric(PZ) coupling to
screened deformation potential(DP) coupling for hole-phonon scattering.
Quantitative comparison with theory shows that the long range PZ coupling
between holes and phonons has the expected magnitude; however, in the metallic
state, the short range DP coupling between holes and phonons is {\it almost
twenty times stronger} than expected from theory. The density dependence of
() shows that it is {\it easier} to cool low density 2D holes in GaAs
than higher density 2D hole systems.Comment: To appear in Phys. Rev. Let
Practitioner review: pathways to care for ADHD - a systematic review of barriers and facilitators
Background. Attention-Deficit/Hyperactivity Disorder (ADHD) is a common neurodevelopmental disorder starting in childhood that may persist into adulthood. It can be managed through carefully monitored medication and nonpharmacological interventions. Access to care for children at risk of ADHD varies both within and between countries. A systematic literature review was conducted to investigate the research evidence related to factors which influence children accessing services for ADHD
Temperature and Magnetic Field Enhanced Hall Slope of a Dilute 2D Hole System in the Ballistic Regime
We report the temperature() and perpendicular magnetic field()
dependence of the Hall resistivity of dilute metallic
two-dimensional(2D) holes in GaAs over a broad range of
temperature(0.02-1.25K). The low Hall coefficient, , is found to be
enhanced when decreases. Strong magnetic fields further enhance the slope
of at all temperatures studied. Coulomb interaction corrections
of a Fermi liquid(FL) in the ballistic regime can not explain the enhancement
of which occurs in the same regime as the anomalous metallic
longitudinal conductivity. In particular, although the metallic conductivity in
2D systems has been attributed to electron interactions in a FL, these same
interactions should reduce, {\it not enhance} the slope of as
decreases and/or increases.Comment: Accepted for publication in Physical Review Letter
Design study of Software-Implemented Fault-Tolerance (SIFT) computer
Software-implemented fault tolerant (SIFT) computer design for commercial aviation is reported. A SIFT design concept is addressed. Alternate strategies for physical implementation are considered. Hardware and software design correctness is addressed. System modeling and effectiveness evaluation are considered from a fault-tolerant point of view
Suppression of weak localization effects in low-density metallic 2D holes
We have measured the conductivity in a gated high-mobility GaAs two
dimensional hole sample with densities in the range (7-17)x10^9 cm^-2 and at
hole temperatures down to 5x10^-3 E_F. We measure the weak localization
corrections to the conductivity g=G/(e^2/h) as a function of magnetic field
(Delta g=0.019 +/- 0.006 at g=1.5 and T=9 mK) and temperature (d ln g/dT<0.0058
and 0.0084 at g=1.56 and 2.8). These values are less than a few percent of the
value 1/pi predicted by standard weak localization theory for a disordered 2D
Fermi liqui
About the parabolic relation existing between the skewness and the kurtosis in time series of experimental data
In this work we investigate the origin of the parabolic relation between
skewness and kurtosis often encountered in the analysis of experimental
time-series. We argue that the numerical values of the coefficients of the
curve may provide informations about the specific physics of the system
studied, whereas the analytical curve per se is a fairly general consequence of
a few constraints expected to hold for most systems.Comment: To appear in Physica Script
High-sensitivity troponin I concentrations are a marker of an advanced hypertrophic response and adverse outcomes in patients with aortic stenosis
Aims:
High-sensitivity cardiac troponin I (cTnI) assays hold promise in detecting the transition from hypertrophy to heart failure in aortic stenosis. We sought to investigate the mechanism for troponin release in patients with aortic stenosis and whether plasma cTnI concentrations are associated with long-term outcome.
Methods and results:
Plasma cTnI concentrations were measured in two patient cohorts using a high-sensitivity assay. First, in the Mechanism Cohort, 122 patients with aortic stenosis (median age 71, 67% male, aortic valve area 1.0 ± 0.4 cm2) underwent cardiovascular magnetic resonance and echocardiography to assess left ventricular (LV) myocardial mass, function, and fibrosis. The indexed LV mass and measures of replacement fibrosis (late gadolinium enhancement) were associated with cTnI concentrations independent of age, sex, coronary artery disease, aortic stenosis severity, and diastolic function. In the separate Outcome Cohort, 131 patients originally recruited into the Scottish Aortic Stenosis and Lipid Lowering Trial, Impact of REgression (SALTIRE) study, had long-term follow-up for the occurrence of aortic valve replacement (AVR) and cardiovascular deaths. Over a median follow-up of 10.6 years (1178 patient-years), 24 patients died from a cardiovascular cause and 60 patients had an AVR. Plasma cTnI concentrations were associated with AVR or cardiovascular death HR 1.77 (95% CI, 1.22 to 2.55) independent of age, sex, systolic ejection fraction, and aortic stenosis severity.
Conclusions:
In patients with aortic stenosis, plasma cTnI concentration is associated with advanced hypertrophy and replacement myocardial fibrosis as well as AVR or cardiovascular death
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