11,021 research outputs found
Prague's Emission Fourier Transform Microwave Spectrometer - Design and Preliminary Results
The design, performance and operation of the high resolution microwave spectrometer are described. The spectrometer is based on the Fabry-Perot resonator supplemented by a pulsed supersonic nozzle for adiabatic cooling of the sample. The spectrometer’s high sensitivity and resolution are demonstrated by several examples
The Shears Mechanism in 142Gd in the Skyrme-Hartree-Fock Method with the Tilted-Axis Cranking
We report on the first Skyrme-Hartree-Fock calculations with the tilted-axis
cranking in the context of magnetic rotation. The mean field symmetries,
differences between phenomenological and self-consistent methods and the
generation of shears-like structures in the mean field are discussed.
Significant role of the time-odd spin-spin effective interaction is pointed
out. We reproduce the shears mechanism, but quantitative agreement with
experiment is rather poor. It may have to do with too large core polarization,
lack of pairing correlations or properties of the Skyrme force.Comment: Presented at the XXVII Mazurian Lakes School of Physics, September
2-9 2001, Krzyze, Poland, Submitted to Acta Physica Polonic
Spontaneous generation of spin-orbit coupling in magnetic dipolar Fermi gases
The stability of an unpolarized two-component dipolar Fermi gas is studied
within mean-field theory. Besides the known instability towards spontaneous
magnetization with Fermi sphere deformation, another instability towards
spontaneous formation of a spin-orbit coupled phase with a Rashba-like spin
texture is found. A phase diagram is presented and consequences are briefly
discussed
Automated Reasoning and Presentation Support for Formalizing Mathematics in Mizar
This paper presents a combination of several automated reasoning and proof
presentation tools with the Mizar system for formalization of mathematics. The
combination forms an online service called MizAR, similar to the SystemOnTPTP
service for first-order automated reasoning. The main differences to
SystemOnTPTP are the use of the Mizar language that is oriented towards human
mathematicians (rather than the pure first-order logic used in SystemOnTPTP),
and setting the service in the context of the large Mizar Mathematical Library
of previous theorems,definitions, and proofs (rather than the isolated problems
that are solved in SystemOnTPTP). These differences poses new challenges and
new opportunities for automated reasoning and for proof presentation tools.
This paper describes the overall structure of MizAR, and presents the automated
reasoning systems and proof presentation tools that are combined to make MizAR
a useful mathematical service.Comment: To appear in 10th International Conference on. Artificial
Intelligence and Symbolic Computation AISC 201
Improving the Sensitivity of Advanced LIGO Using Noise Subtraction
This paper presents an adaptable, parallelizable method for subtracting
linearly coupled noise from Advanced LIGO data. We explain the features
developed to ensure that the process is robust enough to handle the variability
present in Advanced LIGO data. In this work, we target subtraction of noise due
to beam jitter, detector calibration lines, and mains power lines. We
demonstrate noise subtraction over the entirety of the second observing run,
resulting in increases in sensitivity comparable to those reported in previous
targeted efforts. Over the course of the second observing run, we see a 30%
increase in Advanced LIGO sensitivity to gravitational waves from a broad range
of compact binary systems. We expect the use of this method to result in a
higher rate of detected gravitational-wave signals in Advanced LIGO data.Comment: 15 pages, 6 figure
Fast Ground State Manipulation of Neutral Atoms in Microscopic Optical Traps
We demonstrate Rabi flopping at MHz rates between ground hyperfine states of
neutral Rb atoms that are trapped in two micron sized optical traps.
Using tightly focused laser beams we demonstrate high fidelity, site specific
Rabi rotations with crosstalk on neighboring sites separated by at
the level of . Ramsey spectroscopy is used to measure a dephasing time
of which is 5000 times longer than the time for a
pulse.Comment: 4 pages, 4 figure
Two-dimensional array of microtraps with atomic shift register on a chip
Arrays of trapped atoms are the ideal starting point for developing registers
comprising large numbers of physical qubits for storing and processing quantum
information. One very promising approach involves neutral atom traps produced
on microfabricated devices known as atom chips, as almost arbitrary trap
configurations can be realised in a robust and compact package. Until now,
however, atom chip experiments have focused on small systems incorporating
single or only a few individual traps. Here we report experiments on a
two-dimensional array of trapped ultracold atom clouds prepared using a simple
magnetic-film atom chip. We are able to load atoms into hundreds of tightly
confining and optically resolved array sites. We then cool the individual atom
clouds in parallel to the critical temperature required for quantum degeneracy.
Atoms are shuttled across the chip surface utilising the atom chip as an atomic
shift register and local manipulation of atoms is implemented using a focused
laser to rapidly empty individual traps.Comment: 6 pages, 4 figure
Thermodynamics of the Coma Cluster Outskirts
We present results from a large mosaic of Suzaku observations of the Coma
Cluster, the nearest and X-ray brightest hot, dynamically active, non-cool core
system, focusing on the thermodynamic properties of the ICM on large scales.
For azimuths not aligned with an infalling subcluster towards the southwest,
our measured temperature and X-ray brightness profiles exhibit broadly
consistent radial trends, with the temperature decreasing from about 8.5 keV at
the cluster center to about 2 keV at a radius of 2 Mpc, which is the edge of
our detection limit. The SW merger significantly boosts the surface brightness,
allowing us to detect X-ray emission out to ~2.2 Mpc along this direction.
Apart from the southwestern infalling subcluster, the surface brightness
profiles show multiple edges around radii of 30-40 arcmin. The azimuthally
averaged temperature profile, as well as the deprojected density and pressure
profiles, all show a sharp drop consistent with an outward propagating shock
front located at 40 arcmin, corresponding to the outermost edge of the giant
radio halo observed at 352 MHz with the WSRT. The shock front may be powering
this radio emission. A clear entropy excess inside of r_500 reflects the
violent merging events linked with these morphological features. Beyond r_500,
the entropy profiles of the Coma Cluster along the relatively relaxed
directions are consistent with the power-law behavior expected from simple
models of gravitational large-scale structure formation. The pressure is also
in agreement at these radii with the expected values measured from SZ data from
the Planck satellite. However, due to the large uncertainties associated with
the Coma Cluster measurements, we cannot yet exclude an entropy flattening in
this system consistent with that seen in more relaxed cool core clusters.Comment: submitted to ApJ; revised after first referee repor
Rubinstein-Taybi syndrome:dental manifestations and management
Rubinstein-Taybi syndrome (RSTS) is an uncommon genetic disorder characterised by a typical facies, small stature, broad angulated thumbs and intellectual impairment. Dental changes are a minor, yet significant component of the condition. Craniofacial growth retardation in RSTS is frequently complicated by unerupted teeth, while dental caries is related to the inherent intellectual deficit. Dental problems necessitate interdisciplinary management in terms of oral surgery, conservative dentistry, periodontics and orthodontics. When affected individuals are unco-operative, certain dental procedures may warrant general anaesthesia. In these instances, dental and medical staff will combine their expertise to enhance the well-being of the patient. In addition, specific dental changes may alert the medical practitioner to the possible diagnosis of RSTS. In this article we document the oro-dental manifestations and review the oro-dental approach in the management of three patients with RSTS. Our experience in South Africa may be relevant to other countries at a similar stage of development
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