362 research outputs found
Development and Initial Validation of the O&M VISSIT for Orientation and Mobility Specialists to Determine Service Intensity
The purpose of this study was to provide initial validation of the Orientation & Mobility Visual Impairment Scale of Service Intensity of Texas (O&M VISSIT) intended for use by orientation and mobility (O&M) specialists to determine a recommended type and amount of O&M services for students on their caseloads based on each student’s identified needs. The validity and reliability of the scale were calculated using a mixed-methods survey research design, with purposive expert sampling. The O&M VISSIT was found to be significantly valid in social and content validity and moderately valid in consequential validity. The O&M VISSIT is a moderately reliable tool to assist determine the appropriate type and amount of O&M services for all students on the O&M specialist’s caseload
Nonlinear Mechanical Response of DNA due to Anisotropic Bending Elasticity
The response of a short DNA segment to bending is studied, taking into
account the anisotropy in the bending rigidities caused by the double-helical
structure. It is shown that the anisotropy introduces an effective nonlinear
twist-bend coupling that can lead to the formation of kinks and modulations in
the curvature and/or in the twist, depending on the values of the elastic
constants and the imposed deflection angle. The typical wavelength for the
modulations, or the distance between the neighboring kinks is found to be set
by half of the DNA pitch.Comment: 4 pages, 3 encapsulated EPS figure
Device Closure of Secundum Atrial Septal Defects in Children <15 kg Complication Rates and Indications for Referral
ObjectivesThis study sought to determine institutional complication rates in a previously underreported patient population and discuss referral indications.BackgroundThere has been a trend over the years for referral of younger and smaller patients for “elective” closure of atrial septal defects (ASD). In general, the risks associated with ASD device closure are believed and reported to be relatively low. Complication rates in this group of smaller patients are not well described in the literature for either percutaneous or surgical approaches.MethodsRetrospective review of all patients who underwent elective transcatheter closure of secundum ASD between March 2000 and April 2010. We excluded all children >15 kg, as well as those with complex congenital heart defects. Major and minor complications were predefined and indications for referral were evaluated.ResultsWe identified 128 patients meeting criteria with a median procedural age of 1.92 years (3 months to 4.92 years), and median weight of 10.8 kg (4.3 to 14.9 kb). There were 7 major (5.5%) and 12 minor (9.4%) complications. Nearly two-thirds of referrals were for right heart enlargement or poor growth. Rate of resolution of residual shunt was 99%. When compared with age, there was no difference in the rate of resolution of right heart enlargement. No clinically significant improvement in growth was observed.ConclusionsTranscatheter ASD closure in small children is highly successful, but with an increase in previously perceived complication rates. In small, asymptomatic patients, deferral of closure until the historically established timeline of around 4 to 5 years of age should be strongly considered
Cantor type functions in non-integer bases
Cantor's ternary function is generalized to arbitrary base-change functions
in non-integer bases. Some of them share the curious properties of Cantor's
function, while others behave quite differently
CSF metabolites associate with CSF tau and improve prediction of Alzheimer's disease status
Introduction: Cerebrospinal fluid (CSF) total tau (t-tau) and phosphorylated tau (p-tau) are biomarkers of Alzheimer's disease (AD), yet much is unknown about AD-associated changes in tau metabolism and tau tangle etiology. Methods: We assessed the variation of t-tau and p-tau explained by 38 previously identified CSF metabolites using linear regression models in middle-age controls from the Wisconsin Alzheimer's Disease Research Center, and predicted AD/mild cognitive impairment (MCI) versus an independent set of older controls using metabolites selected by the least absolute shrinkage and selection operator (LASSO). Results: The 38 CSF metabolites explained 70.3% and 75.7% of the variance in t-tau and p-tau, respectively. Of these, seven LASSO-selected metabolites improved the prediction ability of AD/MCI versus older controls (area under the curve score increased from 0.92 to 0.97 and 0.78 to 0.93) compared to the base model. Discussion: These tau-correlated CSF metabolites increase AD/MCI prediction accuracy and may provide insight into tau tangle etiology
Local multiresolution order in community detection
Community detection algorithms attempt to find the best clusters of nodes in
an arbitrary complex network. Multi-scale ("multiresolution") community
detection extends the problem to identify the best network scale(s) for these
clusters. The latter task is generally accomplished by analyzing community
stability simultaneously for all clusters in the network. In the current work,
we extend this general approach to define local multiresolution methods, which
enable the extraction of well-defined local communities even if the global
community structure is vaguely defined in an average sense. Toward this end, we
propose measures analogous to variation of information and normalized mutual
information that are used to quantitatively identify the best resolution(s) at
the community level based on correlations between clusters in
independently-solved systems. We demonstrate our method on two constructed
networks as well as a real network and draw inferences about local community
strength. Our approach is independent of the applied community detection
algorithm save for the inherent requirement that the method be able to identify
communities across different network scales, with appropriate changes to
account for how different resolutions are evaluated or defined in a particular
community detection method. It should, in principle, easily adapt to
alternative community comparison measures.Comment: 19 pages, 11 figure
Router-level community structure of the Internet Autonomous Systems
The Internet is composed of routing devices connected between them and
organized into independent administrative entities: the Autonomous Systems. The
existence of different types of Autonomous Systems (like large connectivity
providers, Internet Service Providers or universities) together with
geographical and economical constraints, turns the Internet into a complex
modular and hierarchical network. This organization is reflected in many
properties of the Internet topology, like its high degree of clustering and its
robustness.
In this work, we study the modular structure of the Internet router-level
graph in order to assess to what extent the Autonomous Systems satisfy some of
the known notions of community structure. We show that the modular structure of
the Internet is much richer than what can be captured by the current community
detection methods, which are severely affected by resolution limits and by the
heterogeneity of the Autonomous Systems. Here we overcome this issue by using a
multiresolution detection algorithm combined with a small sample of nodes. We
also discuss recent work on community structure in the light of our results
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