52 research outputs found

    Evaluating Consistency of Snow Water Equivalent Retrievals from Passive Microwave Sensors over the North Central U. S.: SSM/I vs. SSMIS and AMSR-E vs. AMSR2

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    For four decades, satellite-based passive microwave sensors have provided valuable snow water equivalent (SWE) monitoring at a global scale. Before continuous long-term SWE records can be used for scientific or applied purposes, consistency of SWE measurements among different sensors is required. SWE retrievals from two passive sensors currently operating, the Special Sensor Microwave Imager Sounder (SSMIS) and the Advanced Microwave Scanning Radiometer 2 (AMSR2), have not been fully evaluated in comparison to each other and previous instruments. Here, we evaluated consistency between the Special Sensor Microwave/Imager (SSM/I) onboard the F13 Defense Meteorological Satellite Program (DMSP) and SSMIS onboard the F17 DMSP, from November 2002 to April 2011 using the Advanced Microwave Scanning Radiometer for Earth Observing System (AMSR-E) for continuity. Likewise, we evaluated consistency between AMSR-E and AMSR2 SWE retrievals from November 2007 to April 2016, using SSMIS for continuity. The analysis is conducted for 1176 watersheds in the North Central U.S. with consideration of difference among three snow classifications (Warm forest, Prairie, and Maritime). There are notable SWE differences between the SSM/I and SSMIS sensors in the Warm forest class, likely due to the different interpolation methods for brightness temperature (Tb) between the F13 SSM/I and F17 SSMIS sensors. The SWE differences between AMSR2 and AMSR-E are generally smaller than the differences between SSM/I and SSMIS SWE, based on time series comparisons and yearly mean bias. Finally, the spatial bias patterns between AMSR-E and AMSR2 versus SSMIS indicate sufficient spatial consistency to treat the AMSR-E and AMSR2 datasets as one continuous record. Our results provide useful information on systematic differences between recent satellite-based SWE retrievals and suggest subsequent studies to ensure reconciliation between different sensors in long-term SWE records

    Supervised Exercise Intervention and Overall Activity in CKD.

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    Introduction: Patients are often instructed to engage in multiple weekly sessions of exercise to increase physical activity. We aimed to determine whether assignment to a supervised exercise regimen increases overall weekly activity in individuals with chronic kidney disease (CKD). Methods: We performed a secondary analysis of a pilot randomized 2 × 2 factorial design trial examining the effects of diet and exercise (10%-15% reduction in caloric intake, 3 supervised exercise sessions/wk, combined diet restriction/exercise, and control). Activity was measured as counts detected by accelerometer. Counts data were collected on all days for which an accelerometer was worn at baseline, month 2, and month 4 follow-up. The primary outcome was a relative change from baseline in log-transformed counts/min. Generalized estimating equations were used to compare the primary outcome in individuals in the exercise group and the nonexercise group. Results: We examined 111 individuals randomized to aerobic exercise or usual activity (n = 48 in the exercise group and n = 44 controls). The mean age was 57 years, 42% were female, and 28% were black. Median overall adherence over all time was 73%. Median (25th, 75th percentile) counts/min over nonsupervised exercise days at months 2 and 4 were 237.5 (6.5, 444.4) for controls and 250.9 (7.7, 529.8) for the exercise group ( Conclusion: Engaging in a supervised exercise program does not increase overall weekly physical activity in individuals with stage 3 to 4 CKD

    Dual roles for potassium hydride in haloarene reduction : CSNAr and SET reduction via organic electron donors formed in benzene

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    Potassium hydride behaves uniquely and differently than sodium hydride towards aryl halides. Its reactions with a range of haloarenes, including designed 2,6-dialkylhaloarenes, were studied in THF and in benzene. In THF, evidence supports concerted nucleophilic aromatic substitution, CSNAr, and the mechanism originally proposed by Pierre et al. is now validated through DFT studies. In benzene, besides this pathway, strong evidence for single electron transfer chemistry is reported. Experimental observations and DFT studies lead us to propose organic super electron donor generation to initiate BHAS (base-promoted homolytic aromatic substitution) cycles. Organic donor formation originates from deprotonation of benzene by KH; attack on benzene by the resulting phenylpotassium generates phenylcyclohexadienylpotassium that can undergo (i) deprotonation to form an organic super electron donor or (ii) hydride loss to afford biphenyl. Until now, BHAS reactions have been triggered by reaction of a base, MOtBu (M = K, Na), with many different types of organic additive, all containing heteroatoms (N or O or S) that enhance their acidity and place them within range of MOtBu as a base. This paper shows that with the stronger base, KH, even a hydrocarbon (benzene) can be converted into an electron-donating initiator

    A community-based lifestyle and weight loss intervention promoting a Mediterranean-style diet pattern evaluated in the stroke belt of North Carolina: the Heart Healthy Lenoir Project

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    Abstract Background Because residents of the southeastern United States experience disproportionally high rates of cardiovascular disease (CVD), it is important to develop effective lifestyle interventions for this population. Methods The primary objective was to develop and evaluate a dietary, physical activity (PA) and weight loss intervention for residents of the southeastern US. The intervention, given in eastern North Carolina, was evaluated in a 2 year prospective cohort study with an embedded randomized controlled trial (RCT) of a weight loss maintenance intervention. The intervention included: Phase I (months 1–6), individually-tailored intervention promoting a Mediterranean-style dietary pattern and increased walking; Phase II (months 7–12), option of a 16-week weight loss intervention for those with BMI ≥ 25 kg/m2 offered in 2 formats (16 weekly group sessions or 5 group sessions and 10 phone calls) or a lifestyle maintenance intervention; and Phase III (months 13–24), weight loss maintenance RCT for those losing ≥ 8 lb with all other participants receiving a lifestyle maintenance intervention. Change in diet and PA behaviors, CVD risk factors, and weight were assessed at 6, 12, and 24 month follow-up. Results Baseline characteristics (N = 339) were: 260 (77 %) females, 219 (65 %) African Americans, mean age 56 years, and mean body mass index 36 kg/m2. In Phase I, among 251 (74 %) that returned for 6 month follow-up, there were substantial improvements in diet score (4.3 units [95 % CI 3.7 to 5.0]), walking (64 min/week [19 to 109]), and systolic blood pressure (−6.4 mmHg [−8.7 to −4.1]) that were generally maintained through 24 month follow-up. In Phase II, 138 (57 group only, 81 group/phone) chose the weight loss intervention and at 12 months, weight change was: −3.1 kg (−4.9 to −1.3) for group (N = 50) and −2.1 kg (−3.2 to −1.0) for group/phone combination (N = 75). In Phase III, 27 participants took part in the RCT. At 24 months, weight loss was −2.1 kg (−4.3 to 0.0) for group (N = 51) and −1.1 kg (−2.7 to 0.4) for combination (N = 72). Outcomes for African American and whites were similar. Conclusions The intervention yielded substantial improvement in diet, PA, and blood pressure, but weight loss was modest. Trial registration clinicaltrials.gov Identifier: NCT0143348

    The Astropy Problem

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    The Astropy Project (http://astropy.org) is, in its own words, "a community effort to develop a single core package for Astronomy in Python and foster interoperability between Python astronomy packages." For five years this project has been managed, written, and operated as a grassroots, self-organized, almost entirely volunteer effort while the software is used by the majority of the astronomical community. Despite this, the project has always been and remains to this day effectively unfunded. Further, contributors receive little or no formal recognition for creating and supporting what is now critical software. This paper explores the problem in detail, outlines possible solutions to correct this, and presents a few suggestions on how to address the sustainability of general purpose astronomical software

    Conduit artery structure and function in lowlanders and native highlanders: relationships with oxidative stress and role of sympathoexcitation

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    Research detailing the normal vascular adaptions to high altitude is minimal and often confounded by pathology (e.g. chronic mountain sickness) and methodological issues. We examined vascular function and structure in: (1) healthy lowlanders during acute hypoxia and prolonged ( 2 weeks) exposure to high altitude, and (2) high-altitude natives at 5050 m (highlanders). In 12 healthy lowlanders (aged 32 ± 7 years) and 12 highlanders(Sherpa; 33 ± 14 years) we assessed brachial endothelium-dependent flow-mediated dilatation(FMD), endothelium-independent dilatation (via glyceryl trinitrate; GTN), common carotid intima–media thickness (CIMT) and diameter (ultrasound), and arterial stiffness via pulse wave velocity (PWV; applanation tonometry). Cephalic venous biomarkers of free radical-mediated lipid peroxidation (lipid hydroperoxides, LOOH), nitrite (NO2 –) and lipid soluble antioxidants were also obtained at rest. In lowlanders, measurements were performed at sea level (334 m) and between days 3–4 (acute high altitude) and 12–14 (chronic high altitude) following arrival to 5050 m. Highlanders were assessed once at 5050 m. Compared with sea level, acute high altitude reduced lowlanders’ FMD (7.9 ± 0.4 vs. 6.8 ± 0.4%; P = 0.004) and GTN-induced dilatation (16.6 ± 0.9 vs. 14.5 ± 0.8%; P = 0.006), and raised central PWV (6.0 ± 0.2 vs. 6.6 ± 0.3 m s−1; P = 0.001). These changes persisted at days 12–14, and after allometricallyscaling FMD to adjust for altered baseline diameter. Compared to lowlanders at sea level and high altitude, highlanders had a lower carotid wall:lumen ratio ( 19%, P 0.04), attributable to a narrower CIMT and wider lumen. Although both LOOH and NO2 – increased with high altitude in lowlanders, only LOOH correlated with the reduction in GTN-induced dilatation evident during acute (n = 11, r=−0.53) and chronic (n = 7, r=−0.69; P 0.01) exposure to 5050 m. In a follow-up, placebo-controlled experiment (n=11 healthy lowlanders) conducted in a normobaric hypoxic chamber (inspiredO2 fraction (FIO2 )=0.11; 6 h), a sustained reduction in FMD was evident within 1 h of hypoxic exposure when compared to normoxic baseline (5.7±1.6 vs. 8.0 ±1.3%; P < 0.01); this decline in FMD was largely reversed following α1-adrenoreceptor blockade. In conclusion, high-altitude exposure in lowlanders caused persistent impairment in vascular function, which was mediated partially via oxidative stress and sympathoexcitation. Although a lifetime of high-altitude exposure neither intensifies nor attenuates the impairments seen with short-term exposure, chronic high-altitude exposure appears to be associated with arterial remodelling

    Large expert-curated database for benchmarking document similarity detection in biomedical literature search

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    Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe

    2015 American Thyroid Association Management Guidelines for Adult Patients with Thyroid Nodules and Differentiated Thyroid Cancer: The American Thyroid Association Guidelines Task Force on Thyroid Nodules and Differentiated Thyroid Cancer

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    Thyroid nodules are a common clinical problem, and differentiated thyroid cancer is becoming increasingly prevalent. Since the American Thyroid Association's (ATA's) guidelines for the management of these disorders were revised in 2009, significant scientific advances have occurred in the field. The aim of these guidelines is to inform clinicians, patients, researchers, and health policy makers on published evidence relating to the diagnosis and management of thyroid nodules and differentiated thyroid cancer

    Intercomparison of snow water equivalent observations in the Northern Great Plains

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    In the Northern Great Plains, melting snow is a primary driver of spring flooding, but limited knowledge of the magnitude and spatial distribution of snow water equivalent (SWE) hampers flood forecasting. Passive microwave remote sensing has the potential to enhance operational river flow forecasting but is not routinely incorporated in operational flood forecasting. We compare satellite passive microwave estimates from the Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR‐E) to the National Oceanic and Atmospheric Administration Office of Water Prediction (OWP) airborne gamma radiation snow survey and U.S. Army Corps of Engineers (USACE) ground snow survey SWE estimates in the Northern Great Plains from 2002 to 2011. AMSR‐E SWE estimates compare favourably with USACE SWE measurements in the low relief, low vegetation study area (mean difference = −3.8 mm, root mean squared difference [RMSD] = 34.7 mm), but less so with OWP airborne gamma SWE estimates (mean difference = −9.5 mm, RMSD = 42.7 mm). An error simulation suggests that up to half of the error in the former comparison is potentially due to subpixel scale SWE variability, limiting the maximum achievable RMSD between ground and satellite SWE to approximately 26–33 mm in the Northern Great Plains. The OWP gamma versus AMSR‐E SWE comparison yields larger error than the point‐scale USACE versus AMSR‐E comparison, despite a larger measurement footprint (5–7 km2 vs. a few square centimetres, respectively), suggesting that there are unshared errors between the USACE and OWP gamma SWE data
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