2,256 research outputs found
Indicators of implicit and explicit social anxiety influence threat-related interpretive bias as a function of working memory capacity
Interpretive biases play a crucial role in anxiety disorders. The aim of the current study was to examine factors that determine the relative strength of threat-related interpretive biases that are characteristic of individuals high in social anxiety. Different (dual process) models argue that both implicit and explicit processes determine information processing biases and behavior, and that their impact is moderated by the availability of executive resources such as working memory capacity (WMC). Based on these models, we expected indicators of implicit social anxiety to predict threat-related interpretive bias in individuals low, but not high in WMC. Indicators of explicit social anxiety should predict threat-related interpretive bias in individuals high, but not low in WMC. As expected, WMC moderated the impact of implicit social anxiety on threat-related interpretive bias, although the simple slope for individuals low in WMC was not statistically significant. The hypotheses regarding explicit social anxiety (with fear of negative evaluation used as an indicator) were fully supported. The clinical implications of these findings are discussed
Critical behaviour in the nonlinear elastic response of hydrogels
In this paper we study the elastic response of synthetic hydrogels to an
applied shear stress. The hydrogels studied here have previously been shown to
mimic the behaviour of biopolymer networks when they are sufficiently far above
the gel point. We show that near the gel point they exhibit an elastic response
that is consistent with the predicted critical behaviour of networks near or
below the isostatic point of marginal stability. This point separates rigid and
floppy states, distinguished by the presence or absence of finite linear
elastic moduli. Recent theoretical work has also focused on the response of
such networks to finite or large deformations, both near and below the
isostatic point. Despite this interest, experimental evidence for the existence
of criticality in such networks has been lacking. Using computer simulations,
we identify critical signatures in the mechanical response of sub-isostatic
networks as a function of applied shear stress. We also present experimental
evidence consistent with these predictions. Furthermore, our results show the
existence of two distinct critical regimes, one of which arises from the
nonlinear stretch response of semi-flexible polymers.
Barrier and internal wave contributions to the quantum probability density and flux in light heavy-ion elastic scattering
We investigate the properties of the optical model wave function for light
heavy-ion systems where absorption is incomplete, such as Ca
and O around 30 MeV incident energy. Strong focusing effects
are predicted to occur well inside the nucleus, where the probability density
can reach values much higher than that of the incident wave. This focusing is
shown to be correlated with the presence at back angles of a strong enhancement
in the elastic cross section, the so-called ALAS (anomalous large angle
scattering) phenomenon; this is substantiated by calculations of the quantum
probability flux and of classical trajectories. To clarify this mechanism, we
decompose the scattering wave function and the associated probability flux into
their barrier and internal wave contributions within a fully quantal
calculation. Finally, a calculation of the divergence of the quantum flux shows
that when absorption is incomplete, the focal region gives a sizeable
contribution to nonelastic processes.Comment: 16 pages, 15 figures. RevTeX file. To appear in Phys. Rev. C. The
figures are only available via anonynous FTP on
ftp://umhsp02.umh.ac.be/pub/ftp_pnt/figscat
Normal stresses in semiflexible polymer hydrogels
Biopolymer gels such as fibrin and collagen networks are known to develop
tensile axial stress when subject to torsion. This negative normal stress is
opposite to the classical Poynting effect observed for most elastic solids
including synthetic polymer gels, where torsion provokes a positive normal
stress. As recently shown, this anomalous behavior in fibrin gels depends on
the open, porous network structure of biopolymer gels, which facilitates
interstitial fluid flow during shear and can be described by a phenomenological
two-fluid model with viscous coupling between network and solvent. Here we
extend this model and develop a microscopic model for the individual diagonal
components of the stress tensor that determine the axial response of
semi-flexible polymer hydrogels. This microscopic model predicts that the
magnitude of these stress components depends inversely on the characteristic
strain for the onset of nonlinear shear stress, which we confirm experimentally
by shear rheometry on fibrin gels. Moreover, our model predicts a transient
behavior of the normal stress, which is in excellent agreement with the full
time-dependent normal stress we measure.Comment: 12 pages, 8 figure
Bilayer Membrane in Confined Geometry: Interlayer Slide and Steric Repulsion
We derived free energy functional of a bilayer lipid membrane from the first
principles of elasticity theory. The model explicitly includes
position-dependent mutual slide of monolayers and bending deformation. Our free
energy functional of liquid-crystalline membrane allows for incompressibility
of the membrane and vanishing of the in-plane shear modulus and obeys
reflectional and rotational symmetries of the flat bilayer. Interlayer slide at
the mid-plane of the membrane results in local difference of surface densities
of the monolayers. The slide amplitude directly enters free energy via the
strain tensor. For small bending deformations the ratio between bending modulus
and area compression coefficient, Kb/KA, is proportional to the square of
monolayer thickness, h. Using the functional we performed self-consistent
calculation of steric potential acting on bilayer between parallel confining
walls separated by distance 2d. We found that temperature-dependent curvature
at the minimum of confining potential is enhanced four times for a bilayer with
slide as compared with a unit bilayer. We also calculate viscous modes of
bilayer membrane between confining walls. Pure bending of the membrane is
investigated, which is decoupled from area dilation at small amplitudes. Three
sources of viscous dissipation are considered: water and membrane viscosities
and interlayer drag. Dispersion has two branches. Confinement between the walls
modifies the bending mode with respect to membrane in bulk solution.
Simultaneously, inter-layer slipping mode, damped by viscous drag, remains
unchanged by confinement.Comment: 23 pages,3 figures, pd
Development and feasibility testing of an evidence-based occupational therapy program for adults with both Down syndrome and dementia
This paper describes the development of a home-based occupational therapy intervention program for people with Down syndrome who experience early on-set dementia causing a decline in their performance skills and increasing care dependency on their informal caregivers. A six-step methodological process adapted from the Medical Research Council framework for developing and evaluating complex interventions was formulated to develop an evidence-based occupational therapy program for people with both Down syndrome and dementia and their informal caregivers. The first two steps gathered evidence through systematic reviews of the literature and determined the scope of current occupational therapy practice. The gathered evidence was synthesised in step three to develop a client-centred occupational therapy intervention program for persons with both Down syndrome and dementia and their informal caregivers. In steps four and five, opinions were sought from occupational therapists working in this area of practice on the content of the developed program and its feasibility within the Australian disability services context. The final testing step can be conducted in the future using a single-case experimental design study. It is important to use rigorous frameworks and gather comprehensive evidence using multiple methods to develop interventions for small heterogeneous populations. The developed occupational therapy program for persons with both Down syndrome and dementia and their informal caregivers appears feasible to be implemented within the Australian disability services; however, funding limitations imposes barriers for its implementation in clinical practice
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