2,571 research outputs found
Recommended from our members
Supervisees' and supervisors' experiences of group climate in group supervision in psychotherapy. Effects of admission procedure
The purpose of this study was to evaluate the effects of two different admission procedures (high school grades/scholastic aptitude test (SAT) versus high school grades/SAT + interview) to a program in professional psychology on students' and supervisors' experiences of the group climate in psychotherapy supervision groups during an eighteen-month clinical practicum. A self-rating scale constructed to measure experiences of group climate in group supervision in psychotherapy was used. The results showed that students who were admitted based on the alternative admission procedure reported that their supervision groups had a more beneficial climate compared to those who were admitted based on high school grades/SAT. The evaluation suggested that admission via interviews together with high school grades/SAT is a good alternative to traditional admission procedures
Stochastic solutions of Stefan problems
This work deals with the one-dimensional Stefan problem with a general
time-dependent boundary condition at the fixed boundary. Stochastic solutions
are obtained using discrete random walks, and the results are compared with
analytic formulae when they exist, otherwise with numerical solutions from a
finite difference method. The innovative part is to model the moving boundary
with a random walk method. The results show statistical convergence for many
random walkers when . Stochastic methods are very
competitive in large domains in higher dimensions and has the advantages of
generality and ease of implementation. The stochastic method suffers from that
longer execution times are required for increased accuracy. Since the code is
easily adapted for parallel computing, it is possible to speed up the
calculations. Regarding applications for Stefan problems, they have
historically been used to model the dynamics of melting ice, and we give such
an example here where the fixed boundary condition follows data from observed
day temperatures at \"{O}rebro airport. Nowadays, there are a large range of
examples of applications, such as climate models, the diffusion of lithium-ions
in lithium-ion batteries and modelling steam chambers for petroleum extraction.Comment: Submitted as Proceedings to Stochastic Processes and Algebraic
Structures (SPAS) 201
Functional Imaging of Autonomic Regulation: Methods and Key Findings.
Central nervous system processing of autonomic function involves a network of regions throughout the brain which can be visualized and measured with neuroimaging techniques, notably functional magnetic resonance imaging (fMRI). The development of fMRI procedures has both confirmed and extended earlier findings from animal models, and human stroke and lesion studies. Assessments with fMRI can elucidate interactions between different central sites in regulating normal autonomic patterning, and demonstrate how disturbed systems can interact to produce aberrant regulation during autonomic challenges. Understanding autonomic dysfunction in various illnesses reveals mechanisms that potentially lead to interventions in the impairments. The objectives here are to: (1) describe the fMRI neuroimaging methodology for assessment of autonomic neural control, (2) outline the widespread, lateralized distribution of function in autonomic sites in the normal brain which includes structures from the neocortex through the medulla and cerebellum, (3) illustrate the importance of the time course of neural changes when coordinating responses, and how those patterns are impacted in conditions of sleep-disordered breathing, and (4) highlight opportunities for future research studies with emerging methodologies. Methodological considerations specific to autonomic testing include timing of challenges relative to the underlying fMRI signal, spatial resolution sufficient to identify autonomic brainstem nuclei, blood pressure, and blood oxygenation influences on the fMRI signal, and the sustained timing, often measured in minutes of challenge periods and recovery. Key findings include the lateralized nature of autonomic organization, which is reminiscent of asymmetric motor, sensory, and language pathways. Testing brain function during autonomic challenges demonstrate closely-integrated timing of responses in connected brain areas during autonomic challenges, and the involvement with brain regions mediating postural and motoric actions, including respiration, and cardiac output. The study of pathological processes associated with autonomic disruption shows susceptibilities of different brain structures to altered timing of neural function, notably in sleep disordered breathing, such as obstructive sleep apnea and congenital central hypoventilation syndrome. The cerebellum, in particular, serves coordination roles for vestibular stimuli and blood pressure changes, and shows both injury and substantially altered timing of responses to pressor challenges in sleep-disordered breathing conditions. The insights into central autonomic processing provided by neuroimaging have assisted understanding of such regulation, and may lead to new treatment options for conditions with disrupted autonomic function
Perturbative Semiclassical Trace Formulae for Harmonic Oscillators
In this article we extend previous semiclassical studies by including more
general perturbative potentials of the harmonic oscillator in arbitrary spatial
dimensions. Our starting point is a radial harmonic potential with an arbitrary
even monomial perturbation, which we use to study the resulting
to symmetry breaking. We derive the gross structure of the
semiclassical spectrum from periodic orbit theory, in the form of a
perturbative () trace formula. We then show how to apply
the results to even order polynomial potentials, possibly including mean-field
terms. We have drawn the conclusion that the gross structure of the quantum
spectrum is determined from only classical circular- and diameter-orbits for
this class of systems.Comment: Added a comparison with Einstein-Brillouin-Keller theory. To appear
in Reports on Mathematical Physic
Correlated quantum dynamics of graphene
Phase-space representations are a family of methods for dynamics of both
bosonic and fermionic systems, that work by mapping the system's density matrix
to a quasi-probability density and the Liouville-von Neumann equation of the
Hamiltonian to a corresponding density differential equation for the
probability. We investigate here the accuracy and the computational efficiency
of one approximate phase-space representation, called the fermionic Truncated
Wigner Approximation (fTWA), applied to the Fermi-Hubbard model. On a many-body
2D system, with hopping strength and Coulomb tuned to represent the
electronic structure of graphene, the method is found to be able to capture the
time evolution of first-order (site occupation) and second-order (correlation
functions) moments significantly better than the mean-field, Hartree-Fock
method. The fTWA was also compared to results from the exact diagonalization
method for smaller systems, and in general the agreement was found to be good.
The fully parallel computational requirement of fTWA scales in the same order
as the Hartree-Fock method, and the largest system considered here contained
198 lattice sites
Quantum Chaos and Regularity in Ultracold Fermi Gases
Quantum fluctuation of the energy is studied for an ultracold gas of
interacting fermions trapped in a three-dimensional potential. Periodic-orbit
theory is explored, and energy fluctuations are studied versus particle number
for generic regular and chaotic systems, as well for a system defined by a
harmonic confinement potential. Temperature effects on the energy fluctuations
are investigated.Comment: 4 pages, 5 figure
- âŠ