2,086 research outputs found
Sound propagation in choked ducts
The linearized equations describing the propagation of sound in variable area ducts containing flow are shown to be singular when the duct mean flow is sonic. The singularity is removed when previously ignored nonlinear terms are retained. The results of a numerical study, for the case of plane waves propagating in a one-dimensional converging-diverging duct, show that the sound field is adequately described by the linearized equations only when the axial mean flow Mach number at the duct throat M sub th 0.6. For M sub th 0.6, the numerical results showed that acoustic energy flux was not conserved. An attempt was made to extend the study to include the nonlinear behavior of the sound field. Meaningful results were not obtained due, primarily, to numerical difficulties
A stimulus to define informatics and health information technology
<p>Abstract</p> <p>Background</p> <p>Despite the growing interest by leaders, policy makers, and others, the terminology of health information technology as well as biomedical and health informatics is poorly understood and not even agreed upon by academics and professionals in the field.</p> <p>Discussion</p> <p>The paper, presented as a Debate to encourage further discussion and disagreement, provides definitions of the major terminology used in biomedical and health informatics and health information technology. For informatics, it focuses on the words that modify the term as well as individuals who practice the discipline. Other categories of related terms are covered as well, from the associated disciplines of computer science, information technolog and health information management to the major application categories of applications used. The discussion closes with a classification of individuals who work in the largest segment of the field, namely clinical informatics.</p> <p>Summary</p> <p>The goal of presenting in Debate format is to provide a starting point for discussion to reach a documented consensus on the definition and use of these terms.</p
Using co-occurrence network structure to extract synonymous gene and protein names from MEDLINE abstracts
BACKGROUND: Text-mining can assist biomedical researchers in reducing information overload by extracting useful knowledge from large collections of text. We developed a novel text-mining method based on analyzing the network structure created by symbol co-occurrences as a way to extend the capabilities of knowledge extraction. The method was applied to the task of automatic gene and protein name synonym extraction. RESULTS: Performance was measured on a test set consisting of about 50,000 abstracts from one year of MEDLINE. Synonyms retrieved from curated genomics databases were used as a gold standard. The system obtained a maximum F-score of 22.21% (23.18% precision and 21.36% recall), with high efficiency in the use of seed pairs. CONCLUSION: The method performs comparably with other studied methods, does not rely on sophisticated named-entity recognition, and requires little initial seed knowledge
Cyclotomy and Ramanujan sums in quantum phase locking
Phase-locking governs the phase noise in classical clocks through effects
described in precise mathematical terms. We seek here a quantum counterpart of
these effects by working in a finite Hilbert space. We use a coprimality
condition to define phase-locked quantum states and the corresponding
Pegg-Barnett type phase operator. Cyclotomic symmetries in matrix elements are
revealed and related to Ramanujan sums in the theory of prime numbers. The
employed mathematical procedures also emphasize the isomorphism between
algebraic number theory and the theory of quantum entanglementComment: 6 pages, 3 figures, version accepted at Phys. Lett.
Systematic Observations of the Availability and Use of Instructional Technology in Urban Middle School Classrooms
The present study uses systematic observations to investigate the availability and use of instructional technology in 64 middle school classrooms serving predominantly minority students from economically disadvantaged families. The T3 Overall Classroom Observation Measure, a high-inference walk-through instrument, was developed to examine: (a) types and use of technology present in the classroom, (b) teachers’ technology usage, (c) students’ technology usage, (d) teachers’ general instructional behaviors, and (e) students’ general behaviors. The results revealed that instructional technology was widely available in the classrooms, but most teachers and students were only using it to “some extent.
Drag coefficients of microscopic spheres in free-molecule flow
Drag coefficients of microscopic spheres in free molecule flo
The MERG Suite: Tools for discovering competencies and associated learning resources
This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens
Accounting for data heterogeneity in integrative analysis and prediction methods: An application to Chronic Obstructive Pulmonary Disease
Epidemiologic and genetic studies in chronic obstructive pulmonary disease
(COPD) and many complex diseases suggest subgroup disparities (e.g., by sex).
We consider this problem from the standpoint of integrative analysis where we
combine information from different views (e.g., genomics, proteomics, clinical
data). Existing integrative analysis methods ignore the heterogeneity in
subgroups, and stacking the views and accounting for subgroup heterogeneity
does not model the association among the views. To address analytical
challenges in the problem of our interest, we propose a statistical approach
for joint association and prediction that leverages the strengths in each view
to identify molecular signatures that are shared by and specific to males and
females and that contribute to the variation in COPD, measured by airway wall
thickness. HIP (Heterogeneity in Integration and Prediction) accounts for
subgroup heterogeneity, allows for sparsity in variable selection, is
applicable to multi-class and to univariate or multivariate continuous
outcomes, and incorporates covariate adjustment. We develop efficient
algorithms in PyTorch. Our COPD findings have identified several proteins,
genes, and pathways that are common and specific to males and females, some of
which have been implicated in COPD, while others could lead to new insights
into sex differences in COPD mechanisms
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