597 research outputs found
Transient flows in active porous media
Stimuli-responsive materials that modify their shape in response to changes
in environmental conditions -- such as solute concentration, temperature, pH,
and stress -- are widespread in nature and technology. Applications include
micro- and nanoporous materials used in filtration and flow control. The
physiochemical mechanisms that induce internal volume modifications have been
widely studies. The coupling between induced volume changes and solute
transport through porous materials, however, is not well understood. Here, we
consider advective and diffusive transport through a small channel linking two
large reservoirs. A section of stimulus-responsive material regulates the
channel permeability, which is a function of the local solute concentration. We
derive an exact solution to the coupled transport problem and demonstrate the
existence of a flow regime in which the steady state is reached via a damped
oscillation around the equilibrium concentration value. Finally, the
feasibility of an experimental observation of the phenomena is discussed.
Please note that this version of the paper has not been formally peer reviewed,
revised or accepted by a journal
Language performance as a prognostic factor for developing alzheimer's clinical syndrome and mild cognitive impairment: results from the population-based HELIAD cohort
Clinical Neuropsychology as a Specialist Profession in European Health Care : Developing a Benchmark for Training Standards and Competencies Using the Europsy Model?
The prevalence and negative impact of brain disorders are increasing. Clinical Neuropsychology is a specialty dedicated to understanding brain-behavior relationships, applying such knowledge to the assessment of cognitive, affective, and behavioral functioning associated with brain disorders, and designing and implementing effective treatments. The need for services goes beyond neurological diseases and has increased in areas of neurodevelopmental and psychiatric conditions, among others. In Europe, a great deal of variability exists in the education and training of Clinical Neuropsychologists. Training models include master's programs, continuing education courses, doctoral programs, and/or post-doctoral specialization depending on the country, with no common framework of requirements, although patients' needs demand equal competencies across Europe. In the past 5 years, the Standing Committee on Clinical Neuropsychology of the European Federation of Psychologists' Association has conducted a series of surveys and interviews with experts in the field representing 30 European countries. The information, along with information from the existing literature, is used in presenting an overview of current and relevant topics related to policy and guidelines in the training and competencies in Clinical Neuropsychology. An option for the way forward is the EuroPsy Specialist Certificate, which is currently offered in Work and Organizational Psychology, and in psychotherapy. It builds upon the basic certificate and complements national standards without overriding them. General principles can be found that can set the basis for a common, solid, and comprehensive specialty education/training, sharpening the Neuropsychologists' competencies across Europe. The requirements in Clinical Neuropsychology should be comparable to those for the existing specialty areas in the EuroPsy model. Despite the perceived challenges, developing a specialist certificate appears a step forward for the development of Clinical Neuropsychology. Recommendations are proposed toward a shared framework of competencies by the means of a common level of education/training for the professionals in Europe. Benchmarking training standards and competencies across Europe has the potential of providing protection against unqualified and ethically questionable practice, creating transparency, raising the general European standard, and promoting mobility of both Clinical Neuropsychologists and patients in Europe, for the benefit of the professional field and the population.Peer reviewe
Two-dimensional SIR epidemics with long range infection
We extend a recent study of susceptible-infected-removed epidemic processes
with long range infection (referred to as I in the following) from
1-dimensional lattices to lattices in two dimensions. As in I we use hashing to
simulate very large lattices for which finite size effects can be neglected, in
spite of the assumed power law for the
probability that a site can infect another site a distance vector
apart. As in I we present detailed results for the critical case, for the
supercritical case with , and for the supercritical case with . For the latter we verify the stretched exponential growth of the
infected cluster with time predicted by M. Biskup. For we find
generic power laws with dependent exponents in the supercritical
phase, but no Kosterlitz-Thouless (KT) like critical point as in 1-d. Instead
of diverging exponentially with the distance from the critical point, the
correlation length increases with an inverse power, as in an ordinary critical
point. Finally we study the dependence of the critical exponents on in
the regime , and compare with field theoretic predictions. In
particular we discuss in detail whether the critical behavior for
slightly less than 2 is in the short range universality class, as conjectured
recently by F. Linder {\it et al.}. As in I we also consider a modified version
of the model where only some of the contacts are long range, the others being
between nearest neighbors. If the number of the latter reaches the percolation
threshold, the critical behavior is changed but the supercritical behavior
stays qualitatively the same.Comment: 14 pages, including 29 figure
Positive words carry less information than negative words
We show that the frequency of word use is not only determined by the word
length \cite{Zipf1935} and the average information content
\cite{Piantadosi2011}, but also by its emotional content. We have analyzed
three established lexica of affective word usage in English, German, and
Spanish, to verify that these lexica have a neutral, unbiased, emotional
content. Taking into account the frequency of word usage, we find that words
with a positive emotional content are more frequently used. This lends support
to Pollyanna hypothesis \cite{Boucher1969} that there should be a positive bias
in human expression. We also find that negative words contain more information
than positive words, as the informativeness of a word increases uniformly with
its valence decrease. Our findings support earlier conjectures about (i) the
relation between word frequency and information content, and (ii) the impact of
positive emotions on communication and social links.Comment: 16 pages, 3 figures, 3 table
- …