745 research outputs found
The role of cranial and thoracic EMG within diagnostic criteria for ALS.
INTRODUCTION: The contribution of cranial and thoracic region electromyography (EMG) to diagnostic criteria for amyotrophic lateral sclerosis (ALS) has not been evaluated.
METHODS: Clinical and EMG data from each craniospinal region were retrospectively assessed in 470 patients; 214 had ALS. Changes to diagnostic classification in Awaji-Shima and revised El Escorial criteria following withdrawal of cranial/thoracic EMG data were ascertained.
RESULTS: Sensitivity for lower motor neuron involvement in ALS was highest in cervical/lumbar regions; specificity was highest in cranial/thoracic regions. Cranial EMG contributed to definite/probable Awaji-Shima categorization in 1.4% of patients. Thoracic EMG made no contribution. For revised El Escorial criteria, cranial and thoracic data reclassified 1% and 5% of patients, respectively.
CONCLUSION: Cranial EMG data make small contributions to both criteria, thoracic data contribute only to the revised El Escorial criteria. However, cranial and thoracic region abnormalities are specific in ALS. Consideration should be given to allowing greater diagnostic contribution from thoracic EMG
On Invariant Notions of Segre Varieties in Binary Projective Spaces
Invariant notions of a class of Segre varieties \Segrem(2) of PG(2^m - 1,
2) that are direct products of copies of PG(1, 2), being any positive
integer, are established and studied. We first demonstrate that there exists a
hyperbolic quadric that contains \Segrem(2) and is invariant under its
projective stabiliser group \Stab{m}{2}. By embedding PG(2^m - 1, 2) into
\PG(2^m - 1, 4), a basis of the latter space is constructed that is invariant
under \Stab{m}{2} as well. Such a basis can be split into two subsets whose
spans are either real or complex-conjugate subspaces according as is even
or odd. In the latter case, these spans can, in addition, be viewed as
indicator sets of a \Stab{m}{2}-invariant geometric spread of lines of PG(2^m
- 1, 2). This spread is also related with a \Stab{m}{2}-invariant
non-singular Hermitian variety. The case is examined in detail to
illustrate the theory. Here, the lines of the invariant spread are found to
fall into four distinct orbits under \Stab{3}{2}, while the points of PG(7,
2) form five orbits.Comment: 18 pages, 1 figure; v2 - version accepted in Designs, Codes and
Cryptograph
Functional responses can unify invasion ecology.
We contend that invasion ecology requires a universal, measurable trait of species and their interactions with resources that predicts key elements of invasibility and ecological impact; here, we advocate that functional responses can help achieve this across taxonomic and trophic groups, among habitats and contexts, and can hence help unify disparate research interests in invasion ecology
Threats to the validity of the Collegiate Learning Assessment (CLA+) as a measure of critical thinking skills and implications for Learning Gain
The University of Reading Learning Gain project is a three-year longitudinal project to test and evaluate a range of available methodologies and to draw conclusions on what might be the right combination of instruments for the measurement of Learning Gain in higher education. This paper analyses the validity of a measure of critical thinking skills, the Collegiate Learning Assessment (CLA+) and the implications of using this standardised test as a proxy for Learning Gain. The paper reviews five inferences regarding the interpretations and use of test scores: construct representation, scoring, generalisation, extrapolation and decision-making. Each section reviews some of the available evidence in support of the claims the CLA+ makes and the threats to their validity. The possible impact of these issues on Learning Gain in the UK is considered
The clustering instability of inertial particles spatial distribution in turbulent flows
A theory of clustering of inertial particles advected by a turbulent velocity
field caused by an instability of their spatial distribution is suggested. The
reason for the clustering instability is a combined effect of the particles
inertia and a finite correlation time of the velocity field. The crucial
parameter for the clustering instability is a size of the particles. The
critical size is estimated for a strong clustering (with a finite fraction of
particles in clusters) associated with the growth of the mean absolute value of
the particles number density and for a weak clustering associated with the
growth of the second and higher moments. A new concept of compressibility of
the turbulent diffusion tensor caused by a finite correlation time of an
incompressible velocity field is introduced. In this model of the velocity
field, the field of Lagrangian trajectories is not divergence-free. A mechanism
of saturation of the clustering instability associated with the particles
collisions in the clusters is suggested. Applications of the analyzed effects
to the dynamics of droplets in the turbulent atmosphere are discussed. An
estimated nonlinear level of the saturation of the droplets number density in
clouds exceeds by the orders of magnitude their mean number density. The
critical size of cloud droplets required for clusters formation is more than
m.Comment: REVTeX 4, 15 pages, 2 figures(included), PRE submitte
United States Valuation of EQ-5D-5L Health States Using an International Protocol
Objective
To derive a US-based value set for the EQ-5D-5L questionnaire using an international, standardized protocol developed by the EuroQol Group.
Methods
Respondents from the US adult population were quota-sampled on the basis of age, sex, ethnicity, and race. Trained interviewers guided participants in completing composite time trade-off (cTTO) and discrete choice experiment (DCE) tasks using the EuroQol Valuation Technology software and routine quality control measures. Data were modeled using a Tobit model for cTTO data, a mixed logit model for DCE data, and a hybrid model that combined cTTO and DCE data. Model performance was compared on the basis of logical ordering of coefficients, statistical significance, parsimony, and theoretical considerations.
Results
Of 1134 respondents, 1062, 1099, and 1102 respondents provided useable cTTO, DCE, and cTTO or DCE responses, respectively, on the basis of quality control criteria and interviewer judgment. Respondent demographic characteristics and health status were similar to the 2015 US Census. The Tobit model was selected as the preferred model to generate the value set. Values ranged from −0.573 (55 555) to 1 (11 111), with 20% of all predicted health states scores less than 0 (ie, worse than dead).
Conclusions
A societal value set for the EQ-5D-5L was developed that can be used for economic evaluations and decision making in US health systems. The internationally established, standardized protocol used to develop this US-based value set was recommended by the EuroQol Group and can facilitate cross-country comparisons
Perturbation theory for large Stokes number particles in random velocity fields
We derive a perturbative approach to study, in the large inertia limit, the
dynamics of solid particles in a smooth, incompressible and finite-time
correlated random velocity field. We carry on an expansion in powers of the
inverse square root of the Stokes number, defined as the ratio of the
relaxation time for the particle velocities and the correlation time of the
velocity field. We describe in this limit the residual concentration
fluctuations of the particle suspension, and determine the contribution to the
collision statistics produced by clustering. For both concentration
fluctuations and collision velocities, we analyze the differences with the
compressible one-dimensional case.Comment: Latex, 12 pages, 2 eps figures include
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