71 research outputs found
Early Indicators of Academic Difficulties in Children with Neurofibromatosis Type 1
Neurofibromatosis type 1 (NF1) is a genetic neurocutaneous disorder, with an estimated incidence of 1 in 3,000 persons. It is phenotypically variable disorder associated with elevated rates of intellectual disability and learning disabilities, attention problems, speech and language impairment, and executive functioning deficits. Research investigating the presentation of NF1 in preschool-age children is limited, but the data available indicate that cognitive difficulties are present and can be identified at an early age. There is also evidence from the general population that early neuropsychological deficits can be used to predict concurrent and later learning difficulties. The goal of the current study was to characterize the early learning profile of young children with NF1 and to determine which neuropsychological skills may contribute to academic difficulties. The results indicate that early learning difficulties are present and can be identified in young children with NF1. General intellectual functioning was strongly related to academic performance and accounted for many of the relations between neuropsychological and academic skills in the NF1 group. However, some specific neuropsychological skills continued to relate to foundational reading and math skills even when controlling for overall developmental level. These findings provide an indication of processing domains that may support academic skill development for future longitudinal work. Clinically, the findings suggest that cognitive screenings should be a routine part of care for young children with NF1. If appropriate interventions are implemented at an early age, academic skill development could be altered, preventing subtle learning difficulties from becoming more pronounced over time
Excess free energy and Casimir forces in systems with long-range interactions of van-der-Waals type: General considerations and exact spherical-model results
We consider systems confined to a -dimensional slab of macroscopic lateral
extension and finite thickness that undergo a continuous bulk phase
transition in the limit and are describable by an O(n) symmetrical
Hamiltonian. Periodic boundary conditions are applied across the slab. We study
the effects of long-range pair interactions whose potential decays as as , with and , on
the Casimir effect at and near the bulk critical temperature ,
for . For the scaled reduced Casimir force per unit cross-sectional
area, we obtain the form L^{d} {\mathcal F}_C/k_BT \approx \Xi_0(L/\xi_\infty)
+ g_\omega L^{-\omega}\Xi\omega(L/\xi_\infty) + g_\sigma L^{-\omega_\sigm a}
\Xi_\sigma(L \xi_\infty). The contribution decays for
algebraically in rather than exponentially, and hence
becomes dominant in an appropriate regime of temperatures and . We derive
exact results for spherical and Gaussian models which confirm these findings.
In the case , which includes that of nonretarded van-der-Waals
interactions in dimensions, the power laws of the corrections to scaling
of the spherical model are found to get modified by logarithms.
Using general RG ideas, we show that these logarithmic singularities originate
from the degeneracy that occurs for the spherical
model when , in conjunction with the dependence of .Comment: 28 RevTeX pages, 12 eps figures, submitted to PR
An introduction to phase transitions in stochastic dynamical systems
We give an introduction to phase transitions in the steady states of systems
that evolve stochastically with equilibrium and nonequilibrium dynamics, the
latter defined as those that do not possess a time-reversal symmetry. We try as
much as possible to discuss both cases within the same conceptual framework,
focussing on dynamically attractive `peaks' in state space. A quantitative
characterisation of these peaks leads to expressions for the partition function
and free energy that extend from equilibrium steady states to their
nonequilibrium counterparts. We show that for certain classes of nonequilibrium
systems that have been exactly solved, these expressions provide precise
predictions of their macroscopic phase behaviour.Comment: Pedagogical talk contributed to the "Ageing and the Glass Transition"
Summer School, Luxembourg, September 2005. 12 pages, 8 figures, uses the IOP
'jpconf' document clas
Microautophagy of the Nucleus Coincides with a Vacuolar Diffusion Barrier at NuclearāVacuolar Junctions
Nuclear-vacuolar (NV) junctions are organelle contact sites in yeast. They exclude nuclear pores from the organelle interface. On the vacuolar side, a lipid-dependent process excludes specific membrane proteins, such as V-ATPase, from the contact site. This suggests that NV junctions establish selective diffusion barriers
"Best fit" framework synthesis: refining the method
Background
Following publication of the first worked example of the ābest fitā method of evidence synthesis for the systematic review of qualitative evidence in this journal, the originators of the method identified a need to specify more fully some aspects of this particular derivative of framework synthesis.
Methods and Results
We therefore present a second such worked example in which all techniques are defined and explained, and their appropriateness is assessed. Specified features of the method include the development of new techniques to identify theories in a systematic manner; the creation of an a priori framework for the synthesis; and the ātestingā of the synthesis. An innovative combination of existing methods of quality assessment, analysis and synthesis is used to complete the process. This second worked example was a qualitative evidence synthesis of employeesā views of workplace smoking cessation interventions, in which the ābest fitā method was found to be practical and fit for purpose.
Conclusions
The method is suited to producing context-specific conceptual models for describing or explaining the decision-making and health behaviours of patients and other groups. It offers a pragmatic means of conducting rapid qualitative evidence synthesis and generating programme theories relating to intervention effectiveness, which might be of relevance both to researchers and policy-makers
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