7,679 research outputs found
Competition between Electromagnetically Induced Transparency and Raman Processes
We present a theoretical formulation of competition among electromagnetically
induced transparency (EIT) and Raman processes. The latter become important
when the medium can no longer be considered to be dilute. Unlike the standard
formulation of EIT, we consider all fields applied and generated as interacting
with both the transitions of the scheme. We solve Maxwell equations
for the net generated field using a fast-Fourier-transform technique and obtain
predictions for the probe, control and Raman fields. We show how the intensity
of the probe field is depleted at higher atomic number densities due to the
build up of multiple Raman fields.Comment: 3.5 pages, 7 figure
Premise Selection and External Provers for HOL4
Learning-assisted automated reasoning has recently gained popularity among
the users of Isabelle/HOL, HOL Light, and Mizar. In this paper, we present an
add-on to the HOL4 proof assistant and an adaptation of the HOLyHammer system
that provides machine learning-based premise selection and automated reasoning
also for HOL4. We efficiently record the HOL4 dependencies and extract features
from the theorem statements, which form a basis for premise selection.
HOLyHammer transforms the HOL4 statements in the various TPTP-ATP proof
formats, which are then processed by the ATPs. We discuss the different
evaluation settings: ATPs, accessible lemmas, and premise numbers. We measure
the performance of HOLyHammer on the HOL4 standard library. The results are
combined accordingly and compared with the HOL Light experiments, showing a
comparably high quality of predictions. The system directly benefits HOL4 users
by automatically finding proofs dependencies that can be reconstructed by
Metis
The effects of donepezil in Alzheimer's disease - Results from a multinational trial
Donepezil has been shown to be well tolerated and to improve cognition and global function in patients with mild to moderately severe Alzheimer's disease (AD). The current trial was undertaken to investigate further the efficacy and safety of donepezil, in a multinational setting, in patients with mild to moderately severe AD. This 30-week, placebo-controlled, parallel-group study consisted of a 24-week, double-blind treatment phase followed by a 6-week, single-blind, placebo washout. Eight hundred and eighteen patients with mild to moderately severe AD were randomly allocated to treatment with single, daily doses of 5 or 10 mg donepezil, or placebo. The two primary efficacy measures were: a cognitive performance test, the Alzheimer's Disease Assessment Scale-cognitive subscale (ADAS-cog) and a global evaluation, the Clinician's Interview-Based Impression of Change with caregiver input (CIBIC plus). Secondary outcome measures included the Sum of the Boxes of the Clinical Dementia Rating Scale (CDR-SB), a modified Interview for Deterioration in Daily living activities in Dementia (IDDD) and a patient-rated quality of life assessment. Statistically significant improvements in cognitive and global function were observed, as evaluated by ADAS-cog and CIBIC plus, respectively, in both the 5 and 10 mg/day donepezil groups, compared with placebo. Treatment-associated changes were also observed in functional skills, as shown by improved scores on the CDR-SB and the complex-tasks component of the IDDD. A dose-response effect was evident, with the 10 mg/day donepezil group demonstrating greater benefits in all outcome measures than the 5 mg/day group. Donepezil was well tolerated by this patient population and did not produce any clinically significant laboratory test abnormalities. The results of this study confirm that donepezil is effective and well tolerated in treating the symptoms of mild to moderately severe AD
A new paradigm evaluating cost per cure of HCV infection in the UK
Background: New interferon (IFN)-free treatments for hepatitis C are more effective, safer but more expensive than current IFN-based therapies. Comparative data of these, versus current first generation protease inhibitors (PI) with regard to costs and treatment outcomes are needed. We investigated the real-world effectiveness, safety and cost per cure of 1st generation PI-based therapies in the UK. Methods: Medical records review of patients within the HCV Research UK database. Patients had received treatment with telaprevir or boceprevir and pegylated interferon and ribavirin (PR). Data on treatment outcome, healthcare utilisation and adverse events (AEs) requiring intervention were collected and analysed overall and by subgroups. Costs of visits, tests, therapies, adverse events and hospitalisations were estimated at the patient level. Total cost per cure was calculated as total median cost divided by SVR rate. Results: 154 patients from 35 centres were analysed. Overall median total cost per cure was £44,852 (subgroup range,: £35,492 to £107,288). Total treatment costs were accounted for by PI: 68.3 %, PR: 26.3 %, AE management: 5.4 %. Overall SVR was 62.3 % (range 25 % to 86.2 %). 36 % of patients experienced treatment-related AEs requiring intervention, 10 % required treatment-related hospitalisation. Conclusions: This is the first UK multicentre study of outcomes and costs of PI-based HCV treatments in clinical practice. There was substantial variation in total cost per cure among patient subgroups and high rates of treatment-related discontinuations, AEs and hospitalisations. Real world safety, effectiveness and total cost per cure for the new IFN free combinations should be compared against this baseline
Temperature dependence of the energy dissipation in dynamic force microscopy
The dissipation of energy in dynamic force microscopy is usually described in
terms of an adhesion hysteresis mechanism. This mechanism should become less
efficient with increasing temperature. To verify this prediction we have
measured topography and dissipation data with dynamic force microscopy in the
temperature range from 100 K up to 300 K. We used
3,4,9,10-perylenetetracarboxylic-dianhydride (PTCDA) grown on KBr(001), both
materials exhibiting a strong dissipation signal at large frequency shifts. At
room temperature, the energy dissipated into the sample (or tip) is 1.9
eV/cycle for PTCDA and 2.7 eV/cycle for KBr, respectively, and is in good
agreement with an adhesion hysteresis mechanism. The energy dissipation over
the PTCDA surface decreases with increasing temperature yielding a negative
temperature coefficient. For the KBr substrate, we find the opposite behaviour:
an increase of dissipated energy with increasing temperature. While the
negative temperature coefficient in case of PTCDA agrees rather well with the
adhesion hysteresis model, the positive slope found for KBr points to a
hitherto unknown dissipation mechanism
On the Hausdorff volume in sub-Riemannian geometry
For a regular sub-Riemannian manifold we study the Radon-Nikodym derivative
of the spherical Hausdorff measure with respect to a smooth volume. We prove
that this is the volume of the unit ball in the nilpotent approximation and it
is always a continuous function. We then prove that up to dimension 4 it is
smooth, while starting from dimension 5, in corank 1 case, it is C^3 (and C^4
on every smooth curve) but in general not C^5. These results answer to a
question addressed by Montgomery about the relation between two intrinsic
volumes that can be defined in a sub-Riemannian manifold, namely the Popp and
the Hausdorff volume. If the nilpotent approximation depends on the point (that
may happen starting from dimension 5), then they are not proportional, in
general.Comment: Accepted on Calculus and Variations and PD
Heat transport by turbulent Rayleigh-B\'enard convection for $\Pra\ \simeq 0.83\times 10^{12} \alt \Ra\ \alt 10^{15}\Gamma = 0.50$
We report experimental results for heat-transport measurements, in the form
of the Nusselt number \Nu, by turbulent Rayleigh-B\'enard convection in a
cylindrical sample of aspect ratio ( m is
the diameter and m the height). The measurements were made using
sulfur hexafluoride at pressures up to 19 bars as the fluid. They are for the
Rayleigh-number range 3\times 10^{12} \alt \Ra \alt 10^{15} and for Prandtl
numbers \Pra\ between 0.79 and 0.86. For \Ra < \Ra^*_1 \simeq 1.4\times
10^{13} we find \Nu = N_0 \Ra^{\gamma_{eff}} with , consistent with classical turbulent Rayleigh-B\'enard convection in a
system with laminar boundary layers below the top and above the bottom plate.
For \Ra^*_1 < \Ra < \Ra^*_2 (with \Ra^*_2 \simeq 5\times 10^{14})
gradually increases up to . We argue that above
\Ra^*_2 the system is in the ultimate state of convection where the boundary
layers, both thermal and kinetic, are also turbulent. Several previous
measurements for are re-examined and compared with the present
results.Comment: 44 pages, 18 figures, submitted to NJ
Single-Tube Real-Time PCR Assay for Differentiation of Ixodes Affinis and Ixodes scapularis
Ixodes affinis Neumann (1899) and Ixodes scapularis Say (1821) are tick vectors of the etiologic agent of Lyme disease, Borrelia burgdorferi sensu stricto. Ixodes affinis and I. scapularis are morphologically very similar, and as they are sympatric in the mid- and south-Atlantic U.S. coastal states, their accurate identification is crucial to studies of disease and vector ecology in this area. This work describes a rapid, single-tube SYBR® Green-based real-time PCR assay for differentiation of I. affinis and I. scapularis at all life stages. The assay employs 2 pairs of species specific primers directed against the internal transcribed spacer 2 (ITS2) region of the nuclear rRNA operon. Amplification products for these primer pairs differ in size and may be differentiated with a melt curve analysis. This tool is intended as a supplement to morphological methods for accurate identification of these ticks
Newborns' preference for face-relevant stimuli: effects of contrast polarity
There is currently no agreement as to how specific or general are the mechanisms underlying newborns' face preferences. We address this issue by manipulating the contrast polarity of schematic and naturalistic face-related images and assessing the preferences of newborns. We find that for both schematic and naturalistic face images, the contrast polarity is important. Newborns did not show a preference for an upright face-related image unless it was composed of darker areas around the eyes and mouth. This result is consistent with either sensitivity to the shadowed areas of a face with overhead (natural) illumination and/or to the detection of eye contact
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