408 research outputs found
Onset of hexagons in surface-tension-driven Benard convection
High resolution laboratory experiments with large aspect ratio are being conducted for thin fluid layers heated from below and bounded from above by a free surface. The fluid depths are chosen sufficiently small (less than 0.06 cm) so that surface tension is the dominant driving mechanisms; the Rayleigh number is less than 5 for the results reported here. Shadowgraph visualization reveals that the primary instability leading to hexagons is slightly hysteretic (approximately 1 percent). Preliminary measurements of the convection amplitude using infrared imaging are also presented
Synchronised transcranial magnetic stimulation for substance use-disordered Veterans: protocol for the pilot sham-controlled acceptability trial
Introduction: Substance use disorders (SUDs) take an enormous toll on US Veterans and civilians alike. Existing empirically supported interventions vary by substance and demonstrate only moderate efficacy. Non-invasive brain stimulation represents an innovative treatment for SUDs, yet aspects of traditional neurostimulation may hinder its implementation in SUD populations. Synchronised transcranial magnetic stimulation (sTMS) uses rotating rare earth magnets to deliver low-field stimulation synchronised to an individual\u27s alpha peak frequency that is safe for at-home administration. The current trial aims to assess the acceptability and feasibility of sTMS, as well as the safety of at-home sTMS administration for substance-disordered Veterans. Methods and analysis: Sixty Veterans in substance treatment at the Providence Veterans Affairs will be randomised to receive 6 weeks of active or sham sTMS treatment. Eligibility will be confirmed by meeting Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition criteria for an alcohol, cocaine or opioid use disorder. Daily supervised sTMS treatment will occur either in clinic or at home through video monitoring. Clinical and self-report assessments will be completed at baseline, end of treatment and 1-month follow-up. Urine drug screening will occur once per week during the treatment phase. Primary outcomes include treatment adherence/retention and satisfaction to evaluate sTMS feasibility and acceptability in Veterans with SUDs. The safety of at-home sTMS administration will be assessed via adverse event monitoring. Ethics and dissemination: The sTMS device received a significant risk determination for at-home use by the Food and Drug Administration in July 2021. Ethics approval was obtained in August 2021 from the Providence Veterans Affairs institutional review board and research and development committee. Data collection began in September 2021 and is planned to continue through December 2023. Findings will be disseminated at national conferences and in peer-reviewed journals. Results will serve to inform the development of large-scale clinical trials of sTMS efficacy for substance-disordered Veterans. Trial registration number ClinicalTrials.gov Registry (NCT04336293)
Airborne Topographic Mapper Calibration Procedures and Accuracy Assessment
Description of NASA Airborn Topographic Mapper (ATM) lidar calibration procedures including analysis of the accuracy and consistancy of various ATM instrument parameters and the resulting influence on topographic elevation measurements. The ATM elevations measurements from a nominal operating altitude 500 to 750 m above the ice surface was found to be: Horizontal Accuracy 74 cm, Horizontal Precision 14 cm, Vertical Accuracy 6.6 cm, Vertical Precision 3 cm
Airborne Laser/GPS Mapping of Assateague National Seashore Beach
Results are presented from topographic surveys of the Assateague Island National Seashore using recently developed Airborne Topographic Mapper (ATM) and kinematic Global Positioning System (GPS) technology. In November, 1995, and again in May, 1996, the NASA Arctic Ice Mapping (AIM) group from the Goddard Space Flight Center's Wallops Flight Facility conducted the topographic surveys as a part of technology enhancement activities prior to conducting missions to measure the elevation of extensive sections of the Greenland Ice Sheet as part of NASA's Global Climate Change program. Differences between overlapping portions of both surveys are compared for quality control. An independent assessment of the accuracy of the ATM survey is provided by comparison to surface surveys which were conducted using standard techniques. The goal of these projects is to mdke these measurements to an accuracy of +/- 10 cm. Differences between the fall 1995 and 1996 surveys provides an assessment of net changes in the beach morphology over an annual cycle
Continuum-type stability balloon in oscillated granular layers
The stability of convection rolls in a fluid heated from below is limited by
secondary instabilities, including the skew-varicose and crossroll
instabilities. We observe a stability boundary defined by the same
instabilities in stripe patterns in a vertically oscillated granular layer.
Molecular dynamics simulations show that the mechanism of the skew-varicose
instability in granular patterns is similar to that in convection. These
results suggest that pattern formation in granular media can be described by
continuum models analogous to those used in fluid systems.Comment: 4 pages, 6 ps figs, submitted to PR
Surgical management of mesh-related complications after prior pelvic floor reconstructive surgery with mesh
Contains fulltext :
96379.pdf (publisher's version ) (Closed access)INTRODUCTION AND HYPOTHESIS: The objective of this study is to evaluate the complications and anatomical and functional outcomes of the surgical treatment of mesh-related complications. METHODS: A retrospective cohort study of patients who underwent complete or partial mesh excision to treat complications after prior mesh-augmented pelvic floor reconstructive surgery was conducted. RESULTS: Seventy-three patients underwent 30 complete and 51 partial mesh excisions. Intraoperative complications occurred in 4 cases, postoperative complications in 13. Symptom relief was achieved in 92% of patients. Recurrence of pelvic organ prolapse (POP) occurred in 29% of complete and 5% of partial excisions of mesh used in POP surgery. De novo stress urinary incontinence (SUI) occurred in 36% of patients who underwent excision of a suburethral sling. CONCLUSIONS: Mesh excision relieves mesh-related complications effectively, although with a substantial risk of serious complications and recurrence of POP or SUI. More complex excisions should be performed in skilled centers
The use of indigenous knowledge in development: problems and challenges
The use of indigenous knowledge has been seen by many as an alternative way of promoting development in poor rural communities in many parts of the world. By reviewing much of the recent work on indigenous knowledge, the paper suggests that a number of problems and tensions has resulted in indigenous knowledge not being as useful as hoped for or supposed. These include problems emanating from a focus on the (arte)factual; binary tensions between western science and indigenous knowledge systems; the problem of differentiation and power relations; the romanticization of indigenous knowledge; and the all too frequent decontextualization of indigenous knowledge
Does the social context of early alcohol use affect risky drinking in adolescents? Prospective cohort study
BACKGROUND: There are limited longitudinal data on the associations between different social contexts of alcohol use and risky adolescent drinking. METHODS: Australian prospective longitudinal cohort of 1943 adolescents with 6 assessment waves at ages 14-17 years. Drinkers were asked where and how frequently they drank. Contexts were: at home with family, at home alone, at a party with friends, in a park/car, or at a bar/nightclub. The outcomes were prevalence and incidence of risky drinking (≥5 standard drinks (10g alcohol) on a day, past week) and very risky drinking (>20 standard drinks for males and >11 for females) in early (waves 1-2) and late (waves 3-6) adolescence. RESULTS: Forty-four percent (95 % CI: 41-46 %) reported past-week risky drinking on at least one wave during adolescence (waves 1-6). Drinking at a party was the most common repeated drinking context in early adolescence (28 %, 95 % CI 26-30 %); 15 % reported drinking repeatedly (3+ times) with their family in early adolescence (95 % CI: 14-17 %). For all contexts (including drinking with family), drinking 3+ times in a given context was associated with increased the risk of risky drinking in later adolescence. These effects remained apparent after adjustment for potential confounders (e.g. for drinking with family, adjusted RR 1.9; 95 % CI: 1.5-2.4). Similar patterns were observed for very risky drinking. CONCLUSIONS: Our results suggest that consumption with family does not protect against risky drinking. Furthermore, parents who wish to minimise high risk drinking by their adolescent children might also limit their children\u27s opportunities to consume alcohol in unsupervised settings
No evidence for association of ataxia-telangiectasia mutated gene T2119C and C3161G amino acid substitution variants with risk of breast cancer
BACKGROUND: There is evidence that certain mutations in the double-strand break repair pathway ataxia-telangiectasia mutated gene act in a dominant-negative manner to increase the risk of breast cancer. There are also some reports to suggest that the amino acid substitution variants T2119C Ser707Pro and C3161G Pro1054Arg may be associated with breast cancer risk. We investigate the breast cancer risk associated with these two nonconservative amino acid substitution variants using a large Australian population-based case–control study. METHODS: The polymorphisms were genotyped in more than 1300 cases and 600 controls using 5' exonuclease assays. Case–control analyses and genotype distributions were compared by logistic regression. RESULTS: The 2119C variant was rare, occurring at frequencies of 1.4 and 1.3% in cases and controls, respectively (P = 0.8). There was no difference in genotype distribution between cases and controls (P = 0.8), and the TC genotype was not associated with increased risk of breast cancer (adjusted odds ratio = 1.08, 95% confidence interval = 0.59–1.97, P = 0.8). Similarly, the 3161G variant was no more common in cases than in controls (2.9% versus 2.2%, P = 0.2), there was no difference in genotype distribution between cases and controls (P = 0.1), and the CG genotype was not associated with an increased risk of breast cancer (adjusted odds ratio = 1.30, 95% confidence interval = 0.85–1.98, P = 0.2). This lack of evidence for an association persisted within groups defined by the family history of breast cancer or by age. CONCLUSION: The 2119C and 3161G amino acid substitution variants are not associated with moderate or high risks of breast cancer in Australian women
- …