2,047 research outputs found
Second-harmonic generation in vortex-induced waveguides
We study the second-harmonic generation and localization of light in a
reconfigurable waveguide induced by an optical vortex soliton in a defocusing
Kerr medium. We show that the vortex-induced waveguide greatly improves
conversion efficiency from the fundamental to the second harmonic field.Comment: 3 pages, 4 figures, submitted to Optics Letter
StepMix: A Python Package for Pseudo-Likelihood Estimation of Generalized Mixture Models with External Variables
StepMix is an open-source software package for the pseudo-likelihood
estimation (one-, two- and three-step approaches) of generalized finite mixture
models (latent profile and latent class analysis) with external variables
(covariates and distal outcomes). In many applications in social sciences, the
main objective is not only to cluster individuals into latent classes, but also
to use these classes to develop more complex statistical models. These models
generally divide into a measurement model that relates the latent classes to
observed indicators, and a structural model that relates covariates and outcome
variables to the latent classes. The measurement and structural models can be
estimated jointly using the so-called one-step approach or sequentially using
stepwise methods, which present significant advantages for practitioners
regarding the interpretability of the estimated latent classes. In addition to
the one-step approach, StepMix implements the most important stepwise
estimation methods from the literature, including the bias-adjusted three-step
methods with BCH and ML corrections and the more recent two-step approach.
These pseudo-likelihood estimators are presented in this paper under a unified
framework as specific expectation-maximization subroutines. To facilitate and
promote their adoption among the data science community, StepMix follows the
object-oriented design of the scikit-learn library and provides interfaces in
both Python and R.Comment: Sacha Morin and Robin Legault contributed equall
The grid-minor theorem revisited
We prove that for every planar graph of treedepth , there exists a
positive integer such that for every -minor-free graph , there exists
a graph of treewidth at most such that is isomorphic to a
subgraph of . This is a qualitative strengthening of the
Grid-Minor Theorem of Robertson and Seymour (JCTB 1986), and treedepth is the
optimal parameter in such a result. As an example application, we use this
result to improve the upper bound for weak coloring numbers of graphs excluding
a fixed graph as a minor
Advances in prevention and therapy of neonatal dairy calf diarrhoea : a systematical review with emphasis on colostrum management and fluid therapy
Neonatal calf diarrhoea remains the most common cause of morbidity and mortality in preweaned dairy calves worldwide. This complex disease can be triggered by both infectious and non-infectious causes. The four most important enteropathogens leading to neonatal dairy calf diarrhoea are Escherichia coli, rota-and coronavirus, and Cryptosporidium parvum. Besides treating diarrhoeic neonatal dairy calves, the veterinarian is the most obvious person to advise the dairy farmer on prevention and treatment of this disease. This review deals with prevention and treatment of neonatal dairy calf diarrhoea focusing on the importance of a good colostrum management and a correct fluid therapy
Amorphous determination in calcium sulfoaluminate materials by external and internal methods
Sitio Web de la revista: http://www.icevirtuallibrary.com/toc/jadcr/currentExternal standard methodology has been successfully applied to quantify the known amounts of amorphous component that are increasingly added to cement-related materials. The consistency and accuracy of the methodology were demonstrated by the R2 values of the least-square fits determined against weighed amorphous amounts, which were close to 1.0 in all the series. This method requires common laboratory X-ray powder diffractometers (knowing the equipment constant) and avoids the dilution/alteration of the sample. However, the obtained values may be biased due to poor particle statistics. On the other hand, internal standard analysis in transmission geometry is suitable to determine the absolute amorphous and crystalline non-quantified contents that are less biased owing to enhanced particle averaging statistics. This method is, however, experimentally tedious due to the addition of the internal standard and the sample loading in the X-ray diffraction sample holders which represent inherent drawbacks to follow amorphous evolutions
Effectiveness and cost-effectiveness of an educational intervention for practice teams to deliver problem focused therapy for insomnia: rationale and design of a pilot cluster randomised trial
Background: Sleep problems are common, affecting over a third of adults in the United Kingdom and leading to reduced productivity and impaired health-related quality of life. Many of those whose lives are affected seek medical help from primary care. Drug treatment is ineffective long term. Psychological methods for managing sleep problems, including cognitive behavioural therapy for insomnia (CBTi) have been shown to be effective and cost effective but have not been widely implemented or evaluated in a general practice setting where they are most likely to be needed and
most appropriately delivered. This paper outlines the protocol for a pilot study designed to
evaluate the effectiveness and cost-effectiveness of an educational intervention for general practitioners, primary care nurses and other members of the primary care team to deliver problem focused therapy to adult patients presenting with sleep problems due to lifestyle causes, pain or mild to moderate depression or anxiety.
Methods and design: This will be a pilot cluster randomised controlled trial of a complex intervention. General practices will be randomised to an educational intervention for problem focused therapy which includes a consultation approach comprising careful assessment (using assessment of secondary causes, sleep diaries and severity) and use of modified CBTi for insomnia in the consultation compared with usual care (general advice on sleep hygiene and pharmacotherapy with hypnotic drugs). Clinicians randomised to the intervention will receive an educational intervention (2 × 2 hours) to implement a complex intervention of problem focused therapy. Clinicians randomised to the control group will receive reinforcement of usual care with sleep hygiene advice. Outcomes will be assessed via self-completion questionnaires and telephone
interviews of patients and staff as well as clinical records for interventions and prescribing.
Discussion: Previous studies in adults have shown that psychological treatments for insomnia administered by specialist nurses to groups of patients can be effective within a primary care setting. This will be a pilot study to determine whether an educational intervention aimed at primary care teams to deliver problem focused therapy for insomnia can improve sleep management and outcomes for individual adult patients presenting to general practice. The study will also test procedures and collect information in preparation for a larger definitive cluster-randomised trial. The study is funded by The Health Foundation
Gastric Syphilis Mimicking Adenocarcinoma: A Case Report
Syphilis is an unexpected diagnosis in the stomach, and the reduced incidence of syphilis has made its clinical presentation less widely appreciated. We report a 43-yr-old man suffering from epigastric tenderness with an initial diagnosis of gastric carcinoma; gastric syphilis was confirmed by demonstrating spirochetes in a gastric biopsy specimen by silver impregnation. Excessive lymphoplasmacytic infiltration with diffuse thickening of gastric rugae should raise suspicion of gastric syphilis, which should be considered in the differential diagnosis of diffuse erosive gastritis and infiltrative lesions of the stomach
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