11,384 research outputs found
The Children's Revised Impact of Event Scale (CRIES):Validity as a screening instrument for PTSD
The Children's Revised Impact of Event Scale (CRIES) is a brief child-friendly measure designed to screen children at risk for Posttraumatic Stress Disorder (PTSD). It has good face and construct validity, a stable factor structure, correlates well with other indices of distress, and has been used to screen very large samples of at-risk-children following a wide range of traumatic events. However, few studies have examined the scale's validity against a structured diagnostic interview based on the DSM-IV criteria for PTSD. In the present study, the CRIES and the PTSD section of the Anxiety Disorders Interview Schedule-Child and Parent Version (ADIS-CP) were administered to a sample of children and adolescents (n=63) recruited from hospital accident and emergency rooms and the validity of the CRIES as a screening tool evaluated. Cutoff scores were chosen from this sample with a low base-rate of PTSD (11.1%) to maximize sensitivity and minimize the likelihood that children with a diagnosis of PTSD would fail to be identified. Cutoff scores were then cross-validated in a sample of 52 clinically referred children who had a high base-rate of PTSD (67.3%). A cutoff score of 30 on the CRIES-13 and a cutoff score of 17 on the CRIES-8 maximized sensitivity and specificity, minimized the rate of false negatives, and correctly classified 75-83% of the children in the two samples. The CRIES-8 (which lacks any arousal items) worked as efficiently as the CRIES-13 (which includes arousal items) in correctly classifying children with and without PTSD. Results are discussed in light of the current literature and of the need for further development of effective screens for children at-risk of developing PTSD
CubeSats as pathfinders for planetary detection: the FIRST-S satellite
The idea behind FIRST (Fibered Imager foR a Single Telescope) is to use
single-mode fibers to combine multiple apertures in a pupil plane as such as to
synthesize a bigger aperture. The advantages with respect to a pure imager are
i) relaxed tolerance on the pointing and cophasing, ii) higher accuracy in
phase measurement, and iii) availability of compact, precise, and active
single-mode optics like Lithium Niobate. The latter point being a huge asset in
the context of a space mission. One of the problems of DARWIN or SIM-like
projects was the difficulty to find low cost pathfinders missions. But the fact
that Lithium Niobate optic is small and compact makes it easy to test through
small nanosats missions. Moreover, they are commonly used in the telecom
industry, and have already been tested on communication satellites. The idea of
the FIRST-S demonstrator is to spatialize a 3U CubeSat with a Lithium Niobate
nulling interferometer. The technical challenges of the project are: star
tracking, beam combination, and nulling capabilities. The optical baseline of
the interferometer would be 30 cm, giving a 2.2 AU spatial resolution at
distance of 10 pc. The scientific objective of this mission would be to study
the visible emission of exozodiacal light in the habitable zone around the
closest stars.Comment: SPIE 2014 -- Astronomical telescopes and instrumentation -- Montrea
GRAVITY: The AO-Assisted, Two-Object Beam-Combiner Instrument
We present the proposal for the infrared adaptive optics (AO) assisted,
two-object, high-throughput, multiple-beam-combiner GRAVITY for the VLTI. This
instrument will be optimized for phase-referenced interferometric imaging and
narrow-angle astrometry of faint, red objects. Following the scientific
drivers, we analyze the VLTI infrastructure, and subsequently derive the
requirements and concept for the optimum instrument. The analysis can be
summarized with the need for highest sensitivity, phase referenced imaging and
astrometry of two objects in the VLTI beam, and infrared wavefront-sensing.
Consequently our proposed instrument allows the observations of faint, red
objects with its internal infrared wavefront sensor, pushes the optical
throughput by restricting observations to K-band at low and medium spectral
resolution, and is fully enclosed in a cryostat for optimum background
suppression and stability. Our instrument will thus increase the sensitivity of
the VLTI significantly beyond the present capabilities. With its two fibers per
telescope beam, GRAVITY will not only allow the simultaneous observations of
two objects, but will also push the astrometric accuracy for UTs to 10
micro-arcsec, and provide simultaneous astrometry for up to six baselines.Comment: 12 pages, to be published in the Proceedings of the ESO Workshop on
"The Power of Optical/IR Interferometry: Recent Scientific Results and 2nd
Generation VLTI Instrumentation", eds. F. Paresce, A. Richichi, A. Chelli and
F. Delplancke, held in Garching, Germany, 4-8 April 200
A ring trap for ultracold atoms
We propose a new kind of toroidal trap, designed for ultracold atoms. It
relies on a combination of a magnetic trap for rf-dressed atoms, which creates
a bubble-like trap, and a standing wave of light. This new trap is well suited
for investigating questions of low dimensionality in a ring potential. We study
the trap characteristics for a set of experimentally accessible parameters. A
loading procedure from a conventional magnetic trap is also proposed. The
flexible nature of this new ring trap, including an adjustable radius and
adjustable transverse oscillation frequencies, will allow the study of
superfluidity in variable geometries and dimensionalities.Comment: 4 figures, 10 pages ; the order of the sections has been changed ; to
appear in Phys. Rev.
The Structure of High Strehl Ratio Point-Spread Functions
We describe the symmetries present in the point-spread function (PSF) of an
optical system either located in space or corrected by an adaptive o to Strehl
ratios of about 70% and higher. We present a formalism for expanding the PSF to
arbitrary order in terms of powers of the Fourier transform of the residual
phase error, over an arbitrarily shaped and apodized entrance aperture. For
traditional unapodized apertures at high Strehl ratios, bright speckles pinned
to the bright Airy rings are part of an antisymmetric perturbation of the
perfect PSF, arising from the term that is first order in the residual phase
error. There are two symmetric second degree terms. One is negative at the
center, and, like the first order term, is modulated by the perfect image's
field strength -- it reduces to the Marechal approximation at the center of the
PSF. The other is non-negative everywhere, zero at the image center, and can be
responsible for an extended halo -- which limits the dynamic range of faint
companion detection in the darkest portions of the image. In regimes where one
or the other term dominates the speckles in an image, the symmetry of the
dominant term can be exploited to reduce the effect of those speckles,
potentially by an order of magnitude or more. We demonstrate the effects of
both secondary obscuration and pupil apodization on the structure of residual
speckles, and discuss how these symmetries can be exploited by appropriate
telescope and instrument design, observing strategies, and filter bandwidths to
improve the dynamic range of high dynamic range AO and space-based
observations. Finally, we show that our analysis is relevant to high dynamic
range coronagraphy.Comment: Accepted for publication in ApJ; 20 pages, 4 figure
Two-point density correlations of quasicondensates in free expansion
We measure the two-point density correlation function of freely expanding
quasicondensates in the weakly interacting quasi-one-dimensional (1D) regime.
While initially suppressed in the trap, density fluctuations emerge gradually
during expansion as a result of initial phase fluctuations present in the
trapped quasicondensate. Asymptotically, they are governed by the thermal
coherence length of the system. Our measurements take place in an intermediate
regime where density correlations are related to near-field diffraction effects
and anomalous correlations play an important role. Comparison with a recent
theoretical approach described by Imambekov et al. yields good agreement with
our experimental results and shows that density correlations can be used for
thermometry of quasicondensates.Comment: 4 pages, 4 figures, minor change
The GRAVITY fringe tracker: correlation between optical path residuals and atmospheric parameters
After the first year of observations with the GRAVITY fringe tracker, we
compute correlations between the optical path residuals and atmospheric and
astronomical parameters. The median residuals of the optical path residuals are
180 nm on the ATs and 270 nm on the UTs. The residuals are uncorrelated with
the target magnitudes for Kmag below 5.5 on ATs (9 on UTs). The correlation
with the coherence time is however extremely clear, with a drop-off in fringe
tracking performance below 3 ms.Comment: submitted to SPIE Astronomical Telescopes & Instrumentation 201
Interferometer-Type Structures for Guided Atoms
We experimentally demonstrate interferometer-type guiding structures for
neutral atoms based on dipole potentials created by micro-fabricated optical
systems. As a central element we use an array of atom waveguides being formed
by focusing a red-detuned laser beam with an array of cylindrical microlenses.
Combining two of these arrays, we realize X-shaped beam splitters and more
complex systems like the geometries for Mach-Zehnder and Michelson-type
interferometers for atoms.Comment: 4 pages, 6 figure
Longevity of immediate rehabilitation with direct metal-wire reinforced composite fixed partial dentures.
OBJECTIVES
This study aimed to analyze the longevity of direct metal-wire reinforced composite fixed partial dentures (MRC-FPD) and factors influencing their survival and success.
METHODS
Within one private practice 513 MRC-FPD were directly applied. The preparation of a proximal cavity in abutment teeth was not limited. MRC-FPD were reinforced by one to three metal-wires. At the last follow-up MRC-FPD were considered successful, if they were still in function without any need of therapy. MRC-FPD were considered as survived, if they were repaired or replaced. Multi-level Cox proportional hazard models were used to evaluate the association between clinical factors and time.
RESULTS
Mean follow-up period (range) was 59(2-249) months. Seventy-three bridges did not survive (cumulative survival rate(CSR):86%) and further 129 bridges had received a restorative follow-up treatment (CSR:61%). AFR was 2.2% for survival and 8.6% for success. In multivariate analysis MRC-FPD with> 1 wire showed a up to 2.3x higher failure rate than MRC-FPD with one wire(p â€Â 0.023). Dentist's experience in designing MRC-FDP (p â€Â 0.017), patient's caries risk (p â€Â 0.040) and bruxism (p = 0.033) significantly influenced the failure rate: the more experience, the lower caries risk and bruxism, the lower the failure rate.
SIGNIFICANCE
For directly prepared metal-wire reinforced composite bridges high survival and moderate success rates were observed. MRC-FPD might, thus, be an immediate, short- and medium-term solution for replacing missing teeth. However, several factors on the levels of practice (dentist's experience in designing MRC-FDP), patient (bruxism, caries risk) and restoration (number of wires) were identified as significant predictors for the failure rate. The study was registered in the German Clinical Trials Register (DRKS-ID: DRKS00021576)
An optical study of interdiffusion in ZnSe/ZnCdSe
Copyright 1996 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. This article appeared in Applied Physics Letters 69, 1579 (1996) and may be found at
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