1,953 research outputs found
Exploring the feasibility of a meta-structure for DSM-V and ICD-11: Could it improve utility and validity
Diffusing-wave spectroscopy of nonergodic media
We introduce an elegant method which allows the application of diffusing-wave
spectroscopy (DWS) to nonergodic, solid-like samples. The method is based on
the idea that light transmitted through a sandwich of two turbid cells can be
considered ergodic even though only the second cell is ergodic. If absorption
and/or leakage of light take place at the interface between the cells, we
establish a so-called "multiplication rule", which relates the intensity
autocorrelation function of light transmitted through the double-cell sandwich
to the autocorrelation functions of individual cells by a simple
multiplication. To test the proposed method, we perform a series of DWS
experiments using colloidal gels as model nonergodic media. Our experimental
data are consistent with the theoretical predictions, allowing quantitative
characterization of nonergodic media and demonstrating the validity of the
proposed technique.Comment: RevTeX, 12 pages, 6 figures. Accepted for publication in Phys. Rev.
fMRI of reward processing in a community-based longitudinal study
Up to 40% of youth with autism spectrum disorder (ASD) also suffer from
anxiety, and this comorbidity is linked with significant functional
impairment. However, the mechanisms of this overlap are poorly understood. We
investigated the interplay between ASD traits and anxiety during reward
processing, known to be affected in ASD, in a community sample of 1472
adolescents (mean age=14.4 years) who performed a modified monetary incentive
delay task as part of the Imagen project. Blood-oxygen-level dependent (BOLD)
responses to reward anticipation and feedback were compared using a 2x2
analysis of variance test (ASD traits: low/high; anxiety symptoms: low/high),
controlling for plausible covariates. In addition, we used a longitudinal
design to assess whether neural responses during reward processing predicted
anxiety at 2-year follow-up. High ASD traits were associated with reduced BOLD
responses in dorsal prefrontal regions during reward anticipation and negative
feedback. Participants with high anxiety symptoms showed increased lateral
prefrontal responses during anticipation, but decreased responses following
feedback. Interaction effects revealed that youth with combined ASD traits and
anxiety, relative to other youth, showed high right insula activation when
anticipating reward, and low right-sided caudate, putamen, medial and lateral
prefrontal activations during negative feedback (all clusters PFWE<0.05). BOLD
activation patterns in the right dorsal cingulate and right medial frontal
gyrus predicted new-onset anxiety in participants with high but not low ASD
traits. Our results reveal both quantitatively enhanced and qualitatively
distinct neural correlates underlying the comorbidity between ASD traits and
anxiety. Specific neural responses during reward processing may represent a
risk factor for developing anxiety in ASD youth
Effects of Intermittent Caffeine Ingestion on Aerobic Power During a 16.1K Cycling Time Trial
Please view abstract in the attached PDF fil
From Service to Experience: Understanding and Defining the Hospitality Business
Failure adequately to define or understand hospitality as a commercial phenomenon has created a fragmented academic environment and a schizophrenia in the industry that has the potential to limit its development as a global industry. This article suggests that, by redefining hospitality as behaviour and experience, a new perspective emerges that has exciting implications for the management of hospitality businesses. A framework to describe hospitality in the commercial domain is proposed. This framework suggests a focus on the hostâguest relationship, generosity, theatre and performance, âlots of little surprisesâ, and the security of strangers â a focus that provides guests with experiences that are personal, memorable and add value to their lives
Combining navigator and optical prospective motion correction for high-quality 500 ÎŒm resolution quantitative multi-parameter mapping at 7T
Purpose: High-resolution quantitative multi-parameter mapping shows promise for non-invasively characterizing human brain microstructure but is limited by physiological artifacts. We implemented corrections for rigid head movement and respiration-related B0-fluctuations and evaluated them in healthy volunteers and dementia patients. Methods: Camera-based optical prospective motion correction (PMC) and FID navigator correction were implemented in a gradient and RF-spoiled multi-echo 3D gradient echo sequence for mapping proton density (PD), longitudinal relaxation rate (R1) and effective transverse relaxation rate (R2*). We studied their effectiveness separately and in concert in young volunteers and then evaluated the navigator correction (NAVcor) with PMC in a group of elderly volunteers and dementia patients. We used spatial homogeneity within white matter (WM) and gray matter (GM) and scan-rescan measures as quality metrics. Results: NAVcor and PMC reduced artifacts and improved the homogeneity and reproducibility of parameter maps. In elderly participants, NAVcor improved scan-rescan reproducibility of parameter maps (coefficient of variation decreased by 14.7% and 11.9% within WM and GM respectively). Spurious inhomogeneities within WM were reduced more in the elderly than in the young cohort (by 9% vs. 2%). PMC increased regional GM/WM contrast and was especially important in the elderly cohort, which moved twice as much as the young cohort. We did not find a significant interaction between the two corrections. Conclusion: Navigator correction and PMC significantly improved the quality of PD, R1, and R2* maps, particularly in less compliant elderly volunteers and dementia patients. <br
Mixed Weyl Symbol Calculus and Spectral Line Shape Theory
A new and computationally viable full quantum version of line shape theory is
obtained in terms of a mixed Weyl symbol calculus. The basic ingredient in the
collision--broadened line shape theory is the time dependent dipole
autocorrelation function of the radiator-perturber system. The observed
spectral intensity is the Fourier transform of this correlation function. A
modified form of the Wigner--Weyl isomorphism between quantum operators and
phase space functions (Weyl symbols) is introduced in order to describe the
quantum structure of this system. This modification uses a partial Wigner
transform in which the radiator-perturber relative motion degrees of freedom
are transformed into a phase space dependence, while operators associated with
the internal molecular degrees of freedom are kept in their original Hilbert
space form. The result of this partial Wigner transform is called a mixed Weyl
symbol. The star product, Moyal bracket and asymptotic expansions native to the
mixed Weyl symbol calculus are determined. The correlation function is
represented as the phase space integral of the product of two mixed symbols:
one corresponding to the initial configuration of the system, the other being
its time evolving dynamical value. There are, in this approach, two
semiclassical expansions -- one associated with the perturber scattering
process, the other with the mixed symbol star product. These approximations are
used in combination to obtain representations of the autocorrelation that are
sufficiently simple to allow numerical calculation. The leading O(\hbar^0)
approximation recovers the standard classical path approximation for line
shapes. The higher order O(\hbar^1) corrections arise from the noncommutative
nature of the star product.Comment: 26 pages, LaTeX 2.09, 1 eps figure, submitted to 'J. Phys. B.
The Role of Interferon Regulatory Factor-1 and Interferon Regulatory Factor-2 in IFN-Îł Growth Inhibition of Human Breast Carcinoma Cell Lines
Interferon (IFN) regulatory factor-1 (IRF-1) and IRF-2 play opposing roles in the regulation of many IFN-Îł-inducible genes. To investigate the signal transduction pathway in response to IFN-Îł in light of differences in growth effects, we selected four human breast carcinoma cell lines based on a spectrum of growth inhibition by IFN-Îł. MDA468 growth was markedly inhibited by IFN-Îł, and it showed substantial induction of IRF-1 mRNA but little IRF-2 induction. SKBR3 showed little growth inhibition and little induction of IRF-1 mRNA but significant induction of IRF-2 mRNA. HS578T and MDA436 growth inhibition and IRF-1/IRF-2 induction were intermediate. All four cell lines showed intact receptor at the cell surface and Stat1 translocation to the nucleus by immunostaining. By EMSA, there were marked differences in the induced ratio of IRF-1 and IRF-2 binding activity between the cell lines that correlated with growth inhibition. Finally, antisense oligonucleotides specific for IRF-1 attenuated IFN-Îł growth inhibition in MDA436 and MDA468, confirming the direct role of IRF-1 in IFN-Îł growth inhibition. Induction of IRF-1 causes growth inhibition in human breast cancer cell lines, and induction of IRF-2 can oppose this. The relative induction of IRF-1 to IRF-2 is a critical control point in IFN-Îł response.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/63111/1/10799900360708623.pd
Instabilities of waves in nonlinear disordered media
We develop a self-consistent theory of temporal fluctuations of a speckle
pattern resulting from the multiple scattering of a coherent wave in a weakly
nonlinear disordered medium. The speckle pattern is shown to become unstable if
the nonlinearity exceeds a threshold value. The instability is due to a
feedback provided by the multiple scattering and manifests itself in
spontaneous fluctuations of the scattered intensity. The development of
instability is independent of the sign of nonlinearity.Comment: 6 pages, 2 PostScript figures, accepted to Phys. Rev. Let
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