Iterative Methods for Visualization of Implicit Surfaces on GPU

The original publication is available at www.springerlink.comInternational audienceThe ray-casting of implicit surfaces on GPU has been explored in the last few years. However, until recently, they were restricted to second degree (quadrics). We present an iterative solution to ray cast cubics and quartics on GPU. Our solution targets efficient implementation, obtaining interactive rendering for thousands of surfaces per frame. We have given special attention to torus rendering since it is a useful shape for multiple CAD models. We have tested four different iterative methods, including a novel one, comparing them with classical tessellation solution

Antihypertensive medication use during pregnancy in a real-world cohort of patients diagnosed with a hypertensive disorder of pregnancy

Hypertensive disorders of pregnancy (HDP) are rising in prevalence and associated with adverse maternal and infant health outcomes. Current guidelines recommend labetalol, nifedipine, and methyldopa as acceptable first-line agents to treat HDP in outpatient settings. However, the current practice regarding antihypertensive medication usage and selection remain unclear. A retrospective, observational cohort study was conducted in 1,641 patients with a physician diagnosis of HDP who delivered at two academic medical centers in North Carolina from 2014 to 2017. Use of any antihypertensive medication, and the agent selected, at any encounter during pregnancy or on the delivery date was collected from the electronic health record. Proportions were compared across HDP diagnosis (eclampsia/severe preeclampsia, chronic hypertension with superimposed preeclampsia, preeclampsia, gestational hypertension) by Chi-square tests and multivariable logistic regression. Antihypertensive medications were used in 1,276 (77.8%) patients overall. Among treated patients, labetalol (74.9%) was the most frequently used medication followed by nifedipine (29.6%) and hydralazine (20.5%). Methyldopa was used infrequently (4.4%). HDP type was the strongest factor associated with use of an antihypertensive agent. Relative to gestational hypertension, antihypertensive use was significantly more likely [odds ratio (95% CI)] in patients with severe preeclampsia [5.94 (3.85–9.16)], chronic hypertension with superimposed preeclampsia [4.99 (3.46–7.19)], and preeclampsia [2.13 (1.61–2.82)]. In a real-world setting, antihypertensive medication use among HDP patients was common, labetalol, nifedipine, and hydralazine were the most commonly selected agents, and increasing HDP severity was associated with a higher likelihood of antihypertensive use. Future studies comparing medication effectiveness in pregnant patients with distinct HDP diagnoses are needed

Use of troponins in the classification of myocardial infarction from electronic health records. The Atherosclerosis Risk in Communities (ARIC) Study

Objective: Electronic health record (EHR) data are underutilized for abstracting classification criteria for heart disease. We compared extraction of EHR data on troponin I and T levels with human abstraction. Methods: Using EHR for hospitalizations identified through the Atherosclerosis Risk in Communities (ARIC) Study in four US hospitals, we compared blood levels of troponins I and T extracted from EHR structured data elements with levels obtained through data abstraction by human abstractors to 3 decimal places. Observations were divided randomly 50/50 into training and validation sets. Bayesian multilevel logistic regression models were used to estimate agreement by hospital in first and maximum troponin levels, troponin assessment date, troponin upper limit of normal (ULN), and classification of troponin levels as normal (2× ULN), or missing. Results: Estimated overall agreement in first measured troponin level in the validation data was 88.2% (95% credible interval: 65.0%-97.5%) and 95.5% (91.2-98.2%) for the maximum troponin level observed during hospitalization. The largest variation in probability of agreement was for first troponin measured, which ranged from 66.4% to 95.8% among hospitals. Conclusion: Extraction of maximum troponin values during a hospitalization from EHR structured data is feasible and accurate

Environmental modifiers of RTS,S/AS01 malaria vaccine efficacy in Lilongwe, Malawi

Background: RTS,S/AS01 is the first vaccine against malaria to undergo pilot implementation, beginning in 2019 and vaccinating 360,000 children per year in Malawi, Ghana, and Kenya. The four-dose vaccine is given as a primary three-dose series with a fourth dose given approximately 18 months later. The efficacy of RTS,S/AS01 was variable among the 11 sites participating in the 2009-2014 phase III trial (MALARIA-055, NCT00866619), possibly due to differences in transmission intensity. However, a within-site examination of environmental factors related to transmission intensity and their impact on vaccine efficacy has yet to be conducted. Methods: We implemented the phase III RTS,S/AS01 trial at the Malawi site, which enrolled 1578 infants (6-12 weeks) and children (5-17 months) living in the Lilongwe District in Central Malawi and followed them for 3 years between 2009 and 2014. A global positioning system survey and an ecological questionnaire were conducted to collect participant household locations and characteristics, while additional data on background malaria prevalence were obtained from a concurrent Malaria Transmission Intensity (MTI) survey. Negative binomial regression models were used to assess whether the efficacy of the vaccine varied by estimated background malaria prevalence, household roof type, or amount of nearby vegetation. Results: Vaccine efficacy did not significantly vary by estimated malaria prevalence or by roof type. However, increased vegetation cover was associated with an increase in the efficacy of the three-dose primary RTS,S/AS01 series in the 18 months before the fourth dose and a decrease in the efficacy of the primary vaccine series in the second 18 months following, if the fourth dose was not given. Vegetation cover did not alter the efficacy of the fourth dose in a statistically or practically significant manner. Conclusions: Vegetation coverage in this study site might be a proxy for nearness to rivers or branching, shallow wetlands called "dambos"which could serve as breeding sites for mosquitoes. We observed statistically significant modification of the efficacy of RTS,S/AS01 by forest cover, suggesting that initial vaccine efficacy and the importance of the fourth dose varies based on ecological context. Trial registration: Efficacy of GSK Biologicals' Candidate Malaria Vaccine (257049) Against Malaria Disease Caused by P. falciparum Infection in Infants and Children in Africa. NCT00866619 prospectively registered 20 March 2009

Bending the Curve in Cardiovascular Disease Mortality: Bethesda + 40 and beyond

More than 40 years after the 1978 Bethesda Conference on the Declining Mortality from Coronary Heart Disease provided the scientific community with a blueprint for systematic analysis to understand declining rates of coronary heart disease, there are indications the decline has ended or even reversed despite advances in our knowledge about the condition and treatment. Recent data show a more complex situation, with mortality rates for overall cardiovascular disease, including coronary heart disease and stroke, decelerating, whereas those for heart failure are increasing. To mark the 40th anniversary of the Bethesda Conference, the National Heart, Lung, and Blood Institute and the American Heart Association cosponsored the "Bending the Curve in Cardiovascular Disease Mortality: Bethesda + 40" symposium. The objective was to examine the immediate and long-term outcomes of the 1978 conference and understand the current environment. Symposium themes included trends and future projections in cardiovascular disease (in the United States and internationally), the evolving obesity and diabetes epidemics, and harnessing emerging and innovative opportunities to preserve and promote cardiovascular health and prevent cardiovascular disease. In addition, participant-led discussion explored the challenges and barriers in promoting cardiovascular health across the lifespan and established a potential framework for observational research and interventions that would begin in early childhood (or ideally in utero). This report summarizes the relevant research, policy, and practice opportunities discussed at the symposium

Mean value Bézier surfaces

Bézier surfaces are an important design tool in Computer Aided Design. They are parameterized surfaces where the parameterization can be represented as a homogeneous polynomial in barycentric coordinates. Usually, Wachspress coordinates are used to obtain tensor product Bézier surfaces over rectangular domains. Recently, Floater introduced mean value coordinates as an alternative to Wachspress coordinates. When used to construct Bézier patches, they offer additional control points without raising the polynomial degree. We investigate the potential of mean value coordinates to design mean value Bézier surfaces

Recent Advances in Mesh Morphing

Meshes have become a widespread and popular representation of models in computer graphics. Morphing techniques aim at transforming a given source shape into a target shape. Morphing techniques have various applications ranging from special effects in television and movies to medical imaging and scientific visualization. Not surprisingly, morphing techniques for meshes have received a lot of interest lately