1,828 research outputs found
Front localization in a ballistic annihilation model
We study the possibility of localization of the front present in a
one-dimensional ballistically-controlled annihilation model in which the two
annihilating species are initially spatially separated. We construct two
different classes of initial conditions, for which the front remains localized.Comment: Using elsart (Elsevier Latex macro) and epsf. 12 Pages, 2 epsf
figures. Submitted to Physica
Vibrational Exciton Density of States in Solid Benzene
Computerâaided calculations, based on experimentallyâfitted pairwise interaction terms, give the complete exciton densityâofâstates profile for the entire Brillouin zone. The restricted Frenkel model, with shortârange interactions, is the key assumption. Results are given and discussed for the outâofâplane a2ua2u normal mode ν11ν11(C6H6 and C6D6), for ν12(b1u)ν12(b1u), and for ν15(b2u)ν15(b2u). The wide range of parameters used makes this investigation pertinent to other vibrational and electronic exciton bands of benzene and any other molecular crystal with the same interchange symmetry. Also, Van Hove singularities are found to be more important for symmetryâbased critical points than for âaccidentalâ critical points. Presentâday experimental and theoretical intermolecular excitation exchange interaction terms are compared.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71006/2/JCPSA6-53-9-3674-1.pd
McGregor\u27s Theory X/Y and Job Performance: A Multilevel, Multi-source Analysis
McGregor\u27s Theory X/Y (1957; 1960/1985; 1966; 1967), one of the most famous theories of motivation and leadership, has had a profound effect on managerial thinking over the past fifty years. Yet the effect of X/Y attitudes on job performance has never been empirically demonstrated. The present research investigates whether X/Y attitudes and X/Y behaviors-examined as two distinct constructs-are related to job performance. Further, the present research uses a multilevel, multi-source design to examine via hierarchical linear modeling the performance effects of McGregor\u27s (1957; 1960/1985; 1966; 1967) theorizing about managerial assumptions (and behaviors) at both individual and workgroup levels. As predicted, managerial X/Y behaviors fully mediated the relationship between managerial X/Y attitudes and job performance at both the individual and group level. Whereas the three prior X/Y performance-related studies found non-significant relationships between X/Y attitudes and performance (correlations of r = -0.01, r = -0.07, and r = -0.08), the present research found support for the model of X/Y attitudes, X/Y behaviors, and performance with group level coefficients as high as (y = 0.54). Limitations, practical implications, and suggestions for future research are provided
Brownian modulated optical nanoprobes
Brownian modulated optical nanoprobes (Brownian MOONs) are fluorescent micro- and nanoparticles that resemble moons: one hemisphere emits a bright fluorescent signal, while an opaque metal darkens the other hemisphere. Brownian motion causes the particles to tumble and blink erratically as they rotate literally through the phases of the moon. The fluctuating probe signals are separated from optical and electronic backgrounds using principal components analysis or images analysis. Brownian MOONs enable microrheological measurements on size scales and timescales that are difficult to study with other methods. Local chemical concentrations can be measured simultaneously, using spectral characteristics of indicator dyes embedded within the MOONs. Š 2004 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70496/2/APPLAB-84-1-154-1.pd
Biased Social Perceptions of Knowledge: Implications for Negotiators' Rapport and Egocentrism
This study examines how people manage uncertain competitive social interactions. To achieve positive interaction outcomes, individuals may engage in a social perception process that leads them to believe they have obtained more information about others than these others gained about them. We investigate how asymmetric knowledge perceptions contribute to important aspects of negotiation, namely rapport building among strangers and egocentric beliefs about fairness of resource distribution. In Study 1, dyads completed measures of knowledge acquisition and partner evaluation after a rapportâbuilding exercise. Results showed that individuals believed they gained more information about their partner than vice versa; notably, the magnitude of this knowledge bias was associated with more positive partner evaluations. Study 2 showed that the magnitude of the knowledge bias predicted lower egocentrism in a commons dilemma task. Together, these results suggest knowledge asymmetries facilitate rapport among strangers and may have important implications for cooperation in competitive negotiation settings.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/111124/1/ncmr12047.pd
Mentalizing the body: : spatial and social cognition in anosognosia for hemiplegia
Š The Author (2015). Published by Oxford University Press on behalf of the Guarantors of Brain. This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited. For commercial re-use, please contact [email protected] right-hemisphere damage, a specific disorder of motor awareness can occur called anosognosia for hemiplegia, i.e. the denial of motor deficits contralateral to a brain lesion. The study of anosognosia can offer unique insights into the neurocognitive basis of awareness. Typically, however, awareness is assessed as a first person judgement and the ability of patients to think about their bodies in more 'objective' (third person) terms is not directly assessed. This may be important as right-hemisphere spatial abilities may underlie our ability to take third person perspectives. This possibility was assessed for the first time in the present study. We investigated third person perspective taking using both visuospatial and verbal tasks in right-hemisphere stroke patients with anosognosia (n = 15) and without anosognosia (n = 15), as well as neurologically healthy control subjects (n = 15). The anosognosic group performed worse than both control groups when having to perform the tasks from a third versus a first person perspective. Individual analysis further revealed a classical dissociation between most anosognosic patients and control subjects in mental (but not visuospatial) third person perspective taking abilities. Finally, the severity of unawareness in anosognosia patients was correlated to greater impairments in such third person, mental perspective taking abilities (but not visuospatial perspective taking). In voxel-based lesion mapping we also identified the lesion sites linked with such deficits, including some brain areas previously associated with inhibition, perspective taking and mentalizing, such as the inferior and middle frontal gyri, as well as the supramarginal and superior temporal gyri. These results suggest that neurocognitive deficits in mental perspective taking may contribute to anosognosia and provide novel insights regarding the relation between self-awareness and social cognition.Peer reviewe
Dynamic Scaling of an Adsorption-Diffusion Process on Fractals
A dynamic scaling of a diffusion process involving the Langmuir type
adsorption is studied. We find dynamic scaling functions in one and two
dimensions and compare them with direct numerical simulations, and we further
study the dynamic scaling law on fractal surfaces. The adsorption-diffusion
process obeys the fracton dynamics on the fractal surfaces.Comment: 9 pages, 7 figure
Stochastic Ballistic Annihilation and Coalescence
We study a class of stochastic ballistic annihilation and coalescence models
with a binary velocity distribution in one dimension. We obtain an exact
solution for the density which reveals a universal phase diagram for the
asymptotic density decay. By universal we mean that all models in the class are
described by a single phase diagram spanned by two reduced parameters. The
phase diagram reveals four regimes, two of which contain the previously studied
cases of ballistic annihilation. The two new phases are a direct consequence of
the stochasticity. The solution is obtained through a matrix product approach
and builds on properties of a q-deformed harmonic oscillator algebra.Comment: 4 pages RevTeX, 3 figures; revised version with some corrections,
additional discussion and in RevTeX forma
Concentration for One and Two Species One-Dimensional Reaction-Diffusion Systems
We look for similarity transformations which yield mappings between different
one-dimensional reaction-diffusion processes. In this way results obtained for
special systems can be generalized to equivalent reaction-diffusion models. The
coagulation (A + A -> A) or the annihilation (A + A -> 0) models can be mapped
onto systems in which both processes are allowed. With the help of the
coagulation-decoagulation model results for some death-decoagulation and
annihilation-creation systems are given. We also find a reaction-diffusion
system which is equivalent to the two species annihilation model (A + B ->0).
Besides we present numerical results of Monte Carlo simulations. An accurate
description of the effects of the reaction rates on the concentration in
one-species diffusion-annihilation model is made. The asymptotic behavior of
the concentration in the two species annihilation system (A + B -> 0) with
symmetric initial conditions is studied.Comment: 20 pages latex, uuencoded figures at the en
Non-beneficial pediatric research : individual and social interests
Biomedical research involving human subjects is an arena of conflicts of interests. One of the most important conflicts is between interests of participants and interests of future patients. Legal regulations and ethical guidelines are instruments designed to help find a fair balance between risks and burdens taken by research subjects and development of knowledge and new treatment. There is an universally accepted ethical principle, which states that it is not ethically allowed to sacrifice individual interests for the sake of society and science. This is the principle of precedence of individual. But there is a problem with how to interpret the principle of precedence of individual in the context of research without prospect of future benefit involving children. There are proposals trying to reconcile non-beneficial research involving children with the concept of the best interests. We assert that this reconciliation is flawed and propose an interpretation of the principle of precedence of individual as follows: not all, but only the most important interests of participants, must be guaranteed; this principle should be interpreted as the secure participant standard. In consequence, the issue of permissible risk ceiling becomes ethically crucial in research with incompetent subjects
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