1,000 research outputs found
Psychometric Evaluation of the IBD-Specific Anxiety Scale: A Novel Measure of Disease-Related Anxiety for Adolescents With IBD
Anxiety related to pediatric inflammatory bowel disease (IBD) is a common comorbidity; yet, this construct is understudied because of lack of available valid measurement. Objective: The present study will report the preliminary validation of the 20-item IBD-Specific Anxiety Scale (IBD-SAS) in a large, geographically diverse sample of adolescents aged 12-18 years with IBD. Method: A total of 281 adolescents, ages 12-18 (M = 14.8, SD = 1.78; 51% male), completed the IBD-SAS along with measures of IBD-related quality of life, anxiety, depressive symptoms, and disease activity. Factor structure was assessed using exploratory and confirmatory factor analyses (EFA and CFA). Results: EFA (Sample 1; n = 141) yielded one-, two-, three- and four-factor models. The CFA (Sample 2; n = 140) demonstrated that a four-factor model was superior to three- and two-factor model for the amended scale. In total, the IBD-SAS showed excellent internal consistency (Cronbach's à = .95) and was most strongly associated with health-related quality of life. Moderate to strong associations were observed between IBD-SAS and general measures of anxiety and depressive symptoms, and IBD disease activity providing additional support that health-specific anxiety is a valid and distinct construct. Conclusions: Based on the results of this study, the IBD-SAS displayed adequate psychometric properties and can meaningfully contribute to the assessment of IBD-specific anxiety in adolescents diagnosed with IBD, thus filling an empirical and clinical need in this population
Quantum Cosmological Approach to 2d Dilaton Gravity
We study the canonical quantization of the induced 2d-gravity and the pure
gravity CGHS-model on a closed spatial section. The Wheeler-DeWitt equations
are solved in (spatially homogeneous) choices of the internal time variable and
the space of solutions is properly truncated to provide the physical Hilbert
space. We establish the quantum equivalence of both models and relate the
results with the covariant phase-space quantization. We also discuss the
relation between the quantum wavefunctions and the classical space-time
solutions and propose the wave function representing the ground state.Comment: 19 pages, 2 figures (uuencoded) included, plain Latex, needs
amssymb.sty and psfig.sty, FTUV/93-34 & IFIC/93-3
Gravity-induced Wannier-Stark ladder in an optical lattice
We discuss the dynamics of ultracold atoms in an optical potential
accelerated by gravity. The positions and widths of the Wannier-Stark ladder of
resonances are obtained as metastable states. The metastable Wannier-Bloch
states oscillate in a single band with the Bloch period. The width of the
resonance gives the rate transition to the continuum.Comment: 5 pages + 8 eps figures, submitted to Phys. Rev.
Formation of Small-Scale Condensations in the Molecular Clouds via Thermal Instability
A systematic study of the linear thermal instability of a self-gravitating
magnetic molecular cloud is carried out for the case when the unperturbed
background is subject to local expansion or contraction. We consider the
ambipolar diffusion, or ion-neutral friction on the perturbed states. In this
way, we obtain a non-dimensional characteristic equation that reduces to the
prior characteristic equation in the non-gravitating stationary background. By
parametric manipulation of this characteristic equation, we conclude that there
are, not only oblate condensation forming solutions, but also prolate solutions
according to local expansion or contraction of the background. We obtain the
conditions for existence of the Field lengths that thermal instability in the
molecular clouds can occur. If these conditions establish, small-scale
condensations in the form of spherical, oblate, or prolate may be produced via
thermal instability.Comment: 16 page, accepted by Ap&S
Superdeformed rotational bands in the Mercury region; A Cranked Skyrme-Hartree-Fock-Bogoliubov study
A study of rotational properties of the ground superdeformed bands in \Hg{0},
\Hg{2}, \Hg{4}, and \Pb{4} is presented. We use the cranked
Hartree-Fock-Bogoliubov method with the {\skm} parametrization of the Skyrme
force in the particle-hole channel and a seniority interaction in the pairing
channel. An approximate particle number projection is performed by means of the
Lipkin-Nogami prescription. We analyze the proton and neutron quasiparticle
routhians in connection with the present information on about thirty presently
observed superdeformed bands in nuclei close neighbours of \Hg{2}.Comment: 26 LaTeX pages, 14 uuencoded postscript figures included, Preprint
IPN-TH 93-6
Squeezing of Atoms in a Pulsed Optical Lattice
We study the process of squeezing of an ensemble of cold atoms in a pulsed
optical lattice. The problem is treated both classically and
quantum-mechanically under various thermal conditions. We show that a dramatic
compression of the atomic density near the minima of the optical potential can
be achieved with a proper pulsing of the lattice. Several strategies leading to
the enhanced atomic squeezing are suggested, compared and optimized.Comment: Latex, 9 pages, 10 figures, submitted to PR
Momentum state engineering and control in Bose-Einstein condensates
We demonstrate theoretically the use of genetic learning algorithms to
coherently control the dynamics of a Bose-Einstein condensate. We consider
specifically the situation of a condensate in an optical lattice formed by two
counterpropagating laser beams. The frequency detuning between the lasers acts
as a control parameter that can be used to precisely manipulate the condensate
even in the presence of a significant mean-field energy. We illustrate this
procedure in the coherent acceleration of a condensate and in the preparation
of a superposition of prescribed relative phase.Comment: 9 pages incl. 6 PostScript figures (.eps), LaTeX using RevTeX,
submitted to Phys. Rev. A, incl. small modifications, some references adde
Shortest paths on systems with power-law distributed long-range connections
We discuss shortest-path lengths on periodic rings of size L
supplemented with an average of pL randomly located long-range links whose
lengths are distributed according to P_l \sim l^{-\xpn}. Using rescaling
arguments and numerical simulation on systems of up to sites, we show
that a characteristic length exists such that for
. For small p we find
that the shortest-path length satisfies the scaling relation
\ell(r,\xpn,p)/\xi = f(\xpn,r/\xi). Three regions with different asymptotic
behaviors are found, respectively: a) \xpn>2 where , b)
1<\xpn<2 where 0<\theta_s(\xpn)<1/2 and, c) \xpn<1 where
behaves logarithmically, i.e. . The characteristic length is
of the form with \nu=1/(2-\xpn) in region b), but depends
on L as well in region c). A directed model of shortest-paths is solved and
compared with numerical results.Comment: 10 pages, 10 figures, revtex4. Submitted to PR
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