Compressive Phase Contrast Tomography

When x-rays penetrate soft matter, their phase changes more rapidly than their amplitude. In- terference effects visible with high brightness sources creates higher contrast, edge enhanced images. When the object is piecewise smooth (made of big blocks of a few components), such higher con- trast datasets have a sparse solution. We apply basis pursuit solvers to improve SNR, remove ring artifacts, reduce the number of views and radiation dose from phase contrast datasets collected at the Hard X-Ray Micro Tomography Beamline at the Advanced Light Source. We report a GPU code for the most computationally intensive task, the gridding and inverse gridding algorithm (non uniform sampled Fourier transform).Comment: 5 pages, "Image Reconstruction from Incomplete Data VI" conference 7800, SPIE Optical Engineering + Applications 1-5 August 2010 San Diego, CA United State

Saturation and parabolic effects of Langley Calibration at different altitude levels

The performance of the well-known Langley plot technique, used for the calibration of ground-based sunphotometers, has been investigated at three observatory sites of different altitudes. All solar measurements were collected using a portable LED-type sunphotometer programed to a constant measurement protocol to allow direct comparison between different days and sites. Our results show that evaluation on the correlation R-value and slope AOD-value alone is not robust enough to guarantee a good Langley plot. Statistical analysis on global, diffuse and direct component also fails to select a perfect Langley plot within a pool of data available. Instead, examination on the evolution of diffuse component and direct component against global component actually provides a good representation of the performance of Langley plot. Diurnal evolution of diffuse component and direct component was found closely matching to the global component in a similar increasing trend. Our results also highlighted two important effects that greatly govern the performance of Langley plot, which are saturation effect and parabolic effect. Saturation effect occurs for the state when little to no more signal increase can be legibly reflected on Langley plot. It is dominant in low airmass region where the change of airmass is relatively too small for the increase in signal detected by the sunphotometer. Parabolic effect is preceding effect of signal saturation and becomes severely erroneous when high air masses are included in Langley plot

Cost-effectiveness of oral ondansetron for children with acute gastroenteritis in primary care:a randomised controlled trial

BackgroundAcute gastroenteritis is a common childhood condition with substantial medical and indirect costs, mostly because of referral, hospitalisation, and parental absence from work.AimTo determine the cost-effectiveness of adding oral ondansetron to care as usual (CAU) for children with acute gastroenteritis presenting to out-of-hours primary care (OOH-PC).Design and settingA pragmatic randomised controlled trial from December 2015 to January 2018, at three OOH-PC centres in the north of the Netherlands (Groningen, Zwolle, and Assen) with a follow-up of 7 days.MethodChildren were recruited at the OOH-PC and parents kept a parental diary. Inclusion criteria were: aged 6 months-6 years; diagnosis of acute gastroenteritis; at least four reported episodes of vomiting 24 hours before presentation, at least one of which was in the 4 hours before presentation; and written informed consent from both parents. Children were randomly allocated at a 1:1 ratio to either CAU (oral rehydration therapy) or CAU plus one dose of 0.1 mg/kg oral ondansetron.ResultsIn total, 194 children were included for randomisation. One dose of oral ondansetron decreased the proportion of children who continued vomiting within the first 4 hours from 42.9% to 19.5%, (a decrease of 54.5%), with an odds ratio of 0.4 (95% confidence interval [CI] = 0.2 to 0.7; number needed to treat: four). Total mean costs in the ondansetron group were 31.2% lower ((sic)488 [420] pound versus (sic)709 [610]) pound, and the total incremental mean costs for an additional child free of vomiting in the first 4 hours was -(sic)9 (8) pound (95% CI = -(sic)41 [35] pound to (sic)3 [3]) pound.ConclusionA single oral dose of ondansetron for children with acute gastroenteritis, given in OOH-PC settings, is both clinically beneficial and cost-effective.</p

The different clinical faces of obstructive sleep apnoea: a cluster analysis.

To access publisher's full text version of this article click on the hyperlink at the bottom of the pageAlthough commonly observed in clinical practice, the heterogeneity of obstructive sleep apnoea (OSA) clinical presentation has not been formally characterised. This study was the first to apply cluster analysis to identify subtypes of patients with OSA who experience distinct combinations of symptoms and comorbidities. An analysis of baseline data from the Icelandic Sleep Apnoea Cohort (822 patients with newly diagnosed moderate-to-severe OSA) was performed. Three distinct clusters were identified. They were classified as the "disturbed sleep group" (cluster 1), "minimally symptomatic group" (cluster 2) and "excessive daytime sleepiness group" (cluster 3), consisting of 32.7%, 24.7% and 42.6% of the entire cohort, respectively. The probabilities of having comorbid hypertension and cardiovascular disease were highest in cluster 2 but lowest in cluster 3. The clusters did not differ significantly in terms of sex, body mass index or apnoea-hypopnoea index. Patients with OSA have different patterns of clinical presentation, which need to be communicated to both the lay public and the professional community with the goal of facilitating care-seeking and early identification of OSA. Identifying distinct clinical profiles of OSA creates a foundation for offering more personalised therapies in the future

Sleep During Pregnancy: The nuMoM2b Pregnancy and Sleep Duration and Continuity Study

Study Objectives: To characterize sleep duration, timing and continuity measures in pregnancy and their association with key demographic variables. Methods: Multisite prospective cohort study. Women enrolled in the nuMoM2b study (nulliparous women with a singleton gestation) were recruited at the second study visit (16-21 weeks of gestation) to participate in the Sleep Duration and Continuity substudy. Women <18 years of age or with pregestational diabetes or chronic hypertension were excluded from participation. Women wore a wrist activity monitor and completed a sleep log for 7 consecutive days. Time in bed, sleep duration, fragmentation index, sleep efficiency, wake after sleep onset, and sleep midpoint were averaged across valid primary sleep periods for each participant. Results: Valid data were available from 782 women with mean age of 27.3 (5.5) years. Median sleep duration was 7.4 hours. Approximately 27.9% of women had a sleep duration of 9 hours. In multivariable models including age, race/ethnicity, body mass index, insurance status, and recent smoking history, sleep duration was significantly associated with race/ethnicity and insurance status, while time in bed was only associated with insurance status. Sleep continuity measures and sleep midpoint were significantly associated with all covariates in the model, with the exception of age for fragmentation index and smoking for wake after sleep onset. Conclusions: Our results demonstrate the relationship between sleep and important demographic characteristics during pregnancy