504 research outputs found
A Double-Mode RR Lyrae Star with a Strong Fundamental Mode Component
NSVS 5222076, a thirteenth magnitude star in the Northern Sky Variability
Survey, was identified by Oaster as a possible new double-mode RR Lyrae star.
We confirm the double-mode nature of NSVS 5222076, supplementing the survey
data with new V band photometry. NSVS 5222076 has a fundamental mode period of
0.4940 day and a first overtone period of 0.3668 day. Its fundamental mode
light curve has an amplitude twice as large as that of the first overtone mode,
a ratio very rarely seen. Data from the literature are used to discuss the
location in the Petersen diagram of double-mode RR Lyrae stars having strong
fundamental mode pulsation. Such stars tend to occur toward the short period
end of the Petersen diagram, and NSVS 5222976 is no exception to this rule.Comment: 14 pages, 4 figures, To be published in the March, 2006, issue of
PAS
RR Lyrae Variables in the Globular Cluster M55. The First Evidence for Non Radial Pulsations in RR Lyr Stars
We present the results of a photometric study of RR Lyrae variables in the
field of the globular cluster M55. We have discovered nine new RR Lyrae stars,
increasing the number of known variables in this cluster to 15 objects. Five of
the newly discovered variables belong to Bailey type RRc and two to type RRab.
Two background RRab stars are probable members of the Sagittarius dwarf galaxy.
Fourier decomposition of the light curves was used to derive basic properties
of the present sample of RR Lyrae variables. From an analysis of the RRc
variables we obtain a mean mass of , luminosity , effective temperature K, and helium
abundance . Based on the colors, periods and metallicities
of the RRab stars we estimate the value of the color excess for M55 to be equal
to . Using this value we derive the colors of the blue and
red edges of the instability strip in M55. The blue edge lies at
mag and the red edge lies at mag. We estimate the values of the
visual apparent and dereddened distance moduli to be and
, respectively. The light curves of three of the RRc variables
exhibit changes in amplitude of over 0.1 mag on the time scale of less than a
week, rather short for the Blazhko effect, but with no evidence for another
radial pulsational frequency. However we do detect other periodicities which
are clearly visible in the light curve after removing variations with the first
overtone radial frequency. This is strong evidence for the presence of
non-radial pulsations, a behavior common for Scuti stars but not yet
observed among RR Lyr variables.Comment: submitted to Astronomical Journal, 33 pages with 11 figure
Evanescent-wave trapping and evaporative cooling of an atomic gas near two-dimensionality
A dense gas of cesium atoms at the crossover to two-dimensionality is
prepared in a highly anisotropic surface trap that is realized with two
evanescent light waves. Temperatures as low as 100nK are reached with 20.000
atoms at a phase-space density close to 0.1. The lowest quantum state in the
tightly confined direction is populated by more than 60%. The system offers
intriguing prospects for future experiments on degenerate quantum gases in two
dimensions
Титульные страницы и содержание
BACKGROUND: Psychotropic drugs are prescribed to approximately 30-40% of adults with intellectual disability (ID) and challenging behaviour, despite the limited evidence of effectiveness and the potential of adverse events. AIMS: To assess the prevalence of adverse events in association with psychotropic drug use in adults with ID and challenging behaviour and to examine the relation of these adverse events with the person's quality of life. METHOD: The presence of adverse events was measured with a questionnaire that had to be filled in by the physicians of the participants. Movement disorders were measured separately with a standardised protocol. The strength of the association between adverse events and Intellectual Disability Quality of Life-16 (IDQOL-16), and daily functioning was investigated using linear regression analyses, taking into account the severity of disease (CGI-S) as potential confounder. RESULTS: Virtually all of 103 adults with ID and challenging behaviour had at least one adverse event (84.4%) and almost half had ≥3 adverse events (45.6%) across different subclasses. Using psychotropic drugs increased the prevalence of adverse events significantly. Respectively 13% of the patients without psychotropic drugs and 61% of the patients with ≥2 psychotropic drugs had ≥3 adverse events. Having adverse events had a significantly negative influence on the quality of life. CONCLUSIONS: A large majority of all patients had at least one adverse event associated with psychotropic drug use. More attention is needed for these adverse events and their negative influence on the quality of life of these patients, taking into account the lack of evidence of effectiveness of psychotropic drugs for challenging behaviour
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