9,262 research outputs found
Dynamics of the Tippe Top -- properties of numerical solutions versus the dynamical equations
We study the relationship between numerical solutions for inverting Tippe Top
and the structure of the dynamical equations. The numerical solutions confirm
oscillatory behaviour of the inclination angle for the symmetry
axis of the Tippe Top. They also reveal further fine features of the dynamics
of inverting solutions defining the time of inversion. These features are
partially understood on the basis of the underlying dynamical equations
Prospective genetic screening decreases the incidence of Abacavir hypersensitivity reactions in the Western Australian HIV cohort study
Abacavir therapy is associated with significant drug hypersensitivity in ∼8% of recipients, with retrospective studies indicating a strong genetic association with the HLA-B*5701 allelle. In this prospective study, involving 260 abacavir-naive individuals (7.7% of whom were positive for HLA-B*5701), we confirm the usefulness of genetic risk stratification, with no cases of abacavir hypersensitivity among 148 HLA-B*5701–negative recipients
Stationary problems for equation of the KdV type and dynamical -matrices.
We study a quite general family of dynamical -matrices for an auxiliary
loop algebra related to restricted flows for equations of
the KdV type. This underlying -matrix structure allows to reconstruct Lax
representations and to find variables of separation for a wide set of the
integrable natural Hamiltonian systems. As an example, we discuss the
Henon-Heiles system and a quartic system of two degrees of freedom in detail.Comment: 25pp, LaTe
Geometric Phase in Entangled Systems: A Single-Neutron Interferometer Experiment
The influence of the geometric phase on a Bell measurement, as proposed by
Bertlmann et al. in [Phys. Rev. A 69, 032112 (2004)], and expressed by the
Clauser-Horne-Shimony-Holt (CHSH) inequality, has been observed for a spin-path
entangled neutron state in an interferometric setup. It is experimentally
demonstrated that the effect of geometric phase can be balanced by a change in
Bell angles. The geometric phase is acquired during a time dependent
interaction with two radio-frequency (rf) fields. Two schemes, polar and
azimuthal adjustment of the Bell angles, are realized and analyzed in detail.
The former scheme, yields a sinusoidal oscillation of the correlation function
S, dependent on the geometric phase, such that it varies in the range between 2
and 2\sqrt{2} and, therefore, always exceeds the boundary value 2 between
quantum mechanic and noncontextual theories. The latter scheme results in a
constant, maximal violation of the Bell-like-CHSH inequality, where S remains
2\sqrt2 for all settings of the geometric phase.Comment: 10 pages 9 figure
Flux calibration of medium-resolution spectra from 300 nm to 2500 nm: Model reference spectra and telluric correction
While the near-infrared wavelength regime is becoming more and more important
for astrophysics there is a marked lack of spectrophotometric standard star
data that would allow the flux calibration of such data. Furthermore, flux
calibrating medium- to high-resolution \'echelle spectroscopy data is
challenging even in the optical wavelength range, because the available flux
standard data are often too coarsely sampled. We will provide standard star
reference data that allow users to derive response curves from 300nm to 2500nm
for spectroscopic data of medium to high resolution, including those taken with
\'echelle spectrographs. In addition we describe a method to correct for
moderate telluric absorption without the need of observing telluric standard
stars. As reference data for the flux standard stars we use theoretical spectra
derived from stellar model atmospheres. We verify that they provide an
appropriate description of the observed standard star spectra by checking for
residuals in line cores and line overlap regions in the ratios of observed
(X-shooter) spectra to model spectra. The finally selected model spectra are
then corrected for remaining mismatches and photometrically calibrated using
independent observations. The correction of telluric absorption is performed
with the help of telluric model spectra.We provide new, finely sampled
reference spectra without telluric absorption for six southern flux standard
stars that allow the users to flux calibrate their data from 300 nm to 2500 nm,
and a method to correct for telluric absorption using atmospheric models.Comment: Reference spectra available at CDS. Published in A&A 568, A9, 201
New Aspects of Geometric Phases in Experiments with polarized Neutrons
Geometric phase phenomena in single neutrons have been observed in
polarimeter and interferometer experiments. Interacting with static and time
dependent magnetic fields, the state vectors acquire a geometric phase tied to
the evolution within spin subspace. In a polarimeter experiment the
non-additivity of quantum phases for mixed spin input states is observed. In a
Si perfect-crystal interferometer experiment appearance of geometric phases,
induced by interaction with an oscillating magnetic field, is verified. The
total system is characterized by an entangled state, consisting of neutron and
radiation fields, governed by a Jaynes-Cummings Hamiltonian. In addition, the
influence of the geometric phase on a Bell measurement, expressed by the
Clauser-Horne-Shimony-Holt (CHSH) inequality, is studied. It is demonstrated
that the effect of geometric phase can be balanced by an appropriate change of
Bell angles.Comment: 17 pages, 9 figure
The virtual observatory service TheoSSA: Establishing a database of synthetic stellar flux standards. II. NLTE spectral analysis of the OB-type subdwarf Feige 110
In the framework of the Virtual Observatory (VO), the German Astrophysical
Virtual Observatory (GAVO) developed the registered service TheoSSA
(Theoretical Stellar Spectra Access). It provides easy access to stellar
spectral energy distributions (SEDs) and is intended to ingest SEDs calculated
by any model-atmosphere code, generally for all effective temperature, surface
gravities, and elemental compositions. We will establish a database of SEDs of
flux standards that are easily accessible via TheoSSA's web interface.
The OB-type subdwarf Feige 110 is a standard star for flux calibration.
State-of-the-art non-local thermodynamic equilibrium (NLTE) stellar-atmosphere
models that consider opacities of species up to trans-iron elements will be
used to provide a reliable synthetic spectrum to compare with observations.
In case of Feige 110, we demonstrate that the model reproduces not only its
overall continuum shape from the far-ultraviolet (FUV) to the optical
wavelength range but also the numerous metal lines exhibited in its FUV
spectrum.
We present a state-of-the-art spectral analysis of Feige 110. We determined
, and
the abundances of He, N, P, S, Ti, V, Cr, Mn, Fe, Co, Ni, Zn, and Ge. Ti, V,
Mn, Co, Zn, and Ge were identified for the first time in this star. Upper
abundance limits were derived for C, O, Si, Ca, and Sc.
The TheoSSA database of theoretical SEDs of stellar flux standards guarantees
that the flux calibration of astronomical data and cross-calibration between
different instruments can be based on models and SEDs calculated with
state-of-the-art model-atmosphere codes.Comment: 19 pages, 7 figure
Dysphagia in Elderly Women: Consider Tetanus
Background:: Dysphagia is seldom caused by tetanus; however, it is a common symptom of tetanus. Treating patients with tetanus is a rare event in industrialized countries and awareness is needed to recognize early signs of this serious disease. In Switzerland, the most recently reported tetanus cases occurred in elderly women with insufficient seroprotection. Patients:: We report on three elderly women presenting with dysphagia as an initial symptom of tetanus. Results:: Generalized tetanus was diagnosed in two patients upon admission, the third presented with cephalic tetanus with secondary generalization. All three patients had undetectable levels of tetanus antibodies and had no documented prior tetanus immunizations. Cultures of wound swabs grew Clostridium tetani in all cases. Electromyography was highly suggestive for tetanus in two patients. Treatment involved mechanical ventilation, intravenous benzodiazepine and metronidazole therapy, and active and passive tetanus immunization. The disease had a favorable outcome in two cases and was fatal in one. Conclusion:: Tetanus remains a threat in patients with insufficient seroprotection and efforts are needed to improve tetanus immunization in these individuals. Tetanus should be considered in the differential diagnosis of dysphagi
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