2,724 research outputs found

    Pressure Effects in Supercooled Water: Comparison between a 2D Model of Water and Experiments for Surface Water on a Protein

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    Experiments in bulk water confirm the existence of two local arrangements of water molecules with different densities, but, because of inevitable freezing at low temperature TT, can not ascertain whether the two arrangements separate in two phases. To avoid the freezing, new experiments measure the dynamics of water at low TT on the surface of proteins, finding a crossover from a non-Arrhenius regime at high TT to a regime that is approximately Arrhenius at low TT. Motivated by these experiments, Kumar et al. [Phys. Rev. Lett. 100, 105701 (2008)] investigated, by Monte Carlo simulations and mean field calculations, the relation of the dynamic crossover with the coexistence of two liquid phases in a cell model for water and predict that: (i) the dynamic crossover is isochronic, i.e. the value of the crossover time Ļ„L\tau_{\rm L} is approximately independent of pressure PP; (ii) the Arrhenius activation energy EA(P)E_{\rm A}(P) of the low-TT regime decreases upon increasing PP; (iii) the temperature Tāˆ—(P)T^*(P) at which Ļ„\tau reaches a fixed macroscopic time Ļ„āˆ—ā‰„Ļ„L\tau^*\geq \tau_{\rm L} decreases upon increasing PP; in particular, this is true also for the crossover temperature TL(P)T_{\rm L}(P) at which Ļ„=Ļ„L\tau=\tau_{\rm L}. Here, we compare these predictions with recent quasi elastic neutron scattering (QENS) experiments performed by X.-Q. Chu {\it et al.} on hydrated proteins at different values of PP. We find that the experiments are consistent with these three predictions.Comment: 18 pages, 5 figures, to appear on J. Phys.: Cond. Ma

    Swim Instructor Beliefs About Toddler and Pre-School Swimming and Water Safety Education

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    To study the teacher component of the parent-teacher-learner triad in preschool aquatics and explore compatibility of instructor messages with current drowning prevention beliefs, 133 preschool aquatics instructors were surveyed. Instructors with basic swim teacher accreditation and those with a preschool/infant instructor extension (ā€œExtensionā€) were compared. More Extension instructors selected ā€œsafetyā€ as an important outcome (Ļ‡2 = 7.907, df = 3, p = 0.048). Both instructor groups considered parental education important but Extension instructors held this view more strongly. Disturbingly, more Extension instructors disagreed that increased toddler confidence following lessons necessitates greater supervision around water (Ļ‡2 = 4.141, df = 1, p = 0.042). To avoid such messages, instructor education should place even greater emphasis on close and constant adult supervision and counter the misconception that early age lessons protect children from drowning

    Diminished Antioxidant Activity of High-Density Lipoproteinā€“Associated Proteins in Systolic Heart Failure

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    Backgroundā€” Diminished serum arylesterase activity, catalyzed by the high-density lipoproteinā€“associated paraoxonase-1, is associated with heightened systemic oxidative stress and atherosclerosis risk. In the present study, we sought to determine the prognostic role of serum arylesterase activity in subjects with systolic heart failure, particularly in relation to established cardiac biomarkers. Methods and Resultsā€” We measured serum arylesterase activity in 760 subjects with impaired left ventricular systolic function (left ventricular ejection fraction \u3c50%), and prospectively followed major adverse cardiac events (including death, nonfatal myocardial infarction, and stroke) for 3 years. In our study cohort (mean age, 64Ā±11 years; 74% men; median left ventricular ejection fraction, 35%; median creatinine clearance, 96 mg/dL), mean serum arylesterase activity (98Ā±25 Ī¼mol/L/min/mL) was lower compared with that in healthy control subjects (mean, 115Ā±26 Ī¼mol/L/min/mL, P\u3c0.01) but higher compared with advanced decompensated heart failure subjects (mean, 69Ā±22 Ī¼mol/L/min/mL, P\u3c0.01). Within our cohort, there was modest correlation between serum arylesterase activity and high-density lipoprotein cholesterol (r=0.33, P\u3c0.01) as well as B-type natriuretic peptide (r=āˆ’0.23, P\u3c0.01). Lower serum arylesterase activity was a strong predictor of poorer outcomes (hazard ratio, 2.94; 95% confidence interval, 1.54, 5.62; P\u3c0.001). After adjusting for traditional risk factors, medication use, B-type natriuretic peptide, and creatinine clearance, lower serum arylesterase still conferred an increased risk of major adverse cardiac events at 3 years (hazard ratio, 2.69; 95% confidence interval, 1.37 to 5.28; P=0.004). Conclusionsā€” In patients with systolic heart failure, decreased serum arylesterase activity, a measure of diminished antioxidant properties of high-density lipoprotein, predicts higher risk of incident long-term adverse cardiac event independent of established clinical and biochemical risk factors

    Diminished Antioxidant Activity of High-Density Lipoproteinā€“Associated Proteins in Systolic Heart Failure

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    Backgroundā€” Diminished serum arylesterase activity, catalyzed by the high-density lipoproteinā€“associated paraoxonase-1, is associated with heightened systemic oxidative stress and atherosclerosis risk. In the present study, we sought to determine the prognostic role of serum arylesterase activity in subjects with systolic heart failure, particularly in relation to established cardiac biomarkers. Methods and Resultsā€” We measured serum arylesterase activity in 760 subjects with impaired left ventricular systolic function (left ventricular ejection fraction \u3c50%), and prospectively followed major adverse cardiac events (including death, nonfatal myocardial infarction, and stroke) for 3 years. In our study cohort (mean age, 64Ā±11 years; 74% men; median left ventricular ejection fraction, 35%; median creatinine clearance, 96 mg/dL), mean serum arylesterase activity (98Ā±25 Ī¼mol/L/min/mL) was lower compared with that in healthy control subjects (mean, 115Ā±26 Ī¼mol/L/min/mL, P\u3c0.01) but higher compared with advanced decompensated heart failure subjects (mean, 69Ā±22 Ī¼mol/L/min/mL, P\u3c0.01). Within our cohort, there was modest correlation between serum arylesterase activity and high-density lipoprotein cholesterol (r=0.33, P\u3c0.01) as well as B-type natriuretic peptide (r=āˆ’0.23, P\u3c0.01). Lower serum arylesterase activity was a strong predictor of poorer outcomes (hazard ratio, 2.94; 95% confidence interval, 1.54, 5.62; P\u3c0.001). After adjusting for traditional risk factors, medication use, B-type natriuretic peptide, and creatinine clearance, lower serum arylesterase still conferred an increased risk of major adverse cardiac events at 3 years (hazard ratio, 2.69; 95% confidence interval, 1.37 to 5.28; P=0.004). Conclusionsā€” In patients with systolic heart failure, decreased serum arylesterase activity, a measure of diminished antioxidant properties of high-density lipoprotein, predicts higher risk of incident long-term adverse cardiac event independent of established clinical and biochemical risk factors

    A retrospective study of the impact of 21-gene recurrence score assay on treatment choice in node positive micrometastatic breast cancer.

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    To assess clinical utility of the 21-gene assay (Oncotype DXĀ® Recurrence ScoreĀ®), we determined whether women with HER2(āˆ’)/ER+ pN1mi breast cancer with low ( vs. 57.9% in the intermediate-risk group and 100% in the high-risk group (p \u3c 0.001). A total of 80.2% of the low-risk group were recommended endocrine therapy alone, while 77.8% of the high-risk group were recommended both endocrine and chemotherapy (p \u3c 0.001). The Oncotype DX Recurrence Score result provides actionable information that can be incorporated into treatment planning for women with HER2(āˆ’)/ER+ pN1mi breast cancer. The Recurrence Score result has clinical utility in treatment planning for HER2(āˆ’)/ER+ pN1mi breast cancer patients

    Cluster Monte Carlo and numerical mean field analysis for the water liquid--liquid phase transition

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    By the Wolff's cluster Monte Carlo simulations and numerical minimization within a mean field approach, we study the low temperature phase diagram of water, adopting a cell model that reproduces the known properties of water in its fluid phases. Both methods allows us to study the water thermodynamic behavior at temperatures where other numerical approaches --both Monte Carlo and molecular dynamics-- are seriously hampered by the large increase of the correlation times. The cluster algorithm also allows us to emphasize that the liquid--liquid phase transition corresponds to the percolation transition of tetrahedrally ordered water molecules.Comment: 6 pages, 3 figure

    Swim instructor beliefs about toddler and preschool swimming and water safety education

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    To study the teacher component of the parent-teacher-learner triad in preschool aquatics and explore compatibility of instructor messages with current drowning prevention beliefs, 133 preschool aquatics instructors were surveyed. Instructors with basic swim teacher accreditation and those with a preschool/infant instructor extension ("Extension") were compared. More Extension instructors selected "safety" as an important outcome

    Intestinal Microbiota-Dependent Phosphatidylcholine Metabolites, Diastolic Dysfunction, and Adverse Clinical Outcomes in Chronic Systolic Heart Failure

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    Background: Trimethylamine-N-oxide (TMAO) has been linked to increased cardiovascular risk. We aimed to determine the prognostic value of TMAO and its dietary precursors, choline and betaine, in heart failure (HF). Methods and Results: In 112 patients with chronic systolic HF with comprehensive echocardiographic evaluation, we measured plasma TMAO, choline, and betaine by mass spectrometry. Median (interquartile range) TMAO levels, choline, and betaine levels were 5.8 (3.6ā€“12.1) Ī¼mol/L, 10.9 (8.4ā€“14.0) Ī¼mol/L, and 43.8 (37.1ā€“53.0) Ī¼mol/L, respectively, and were correlated with each other (all P \u3c .0001 for both). TMAO levels were significantly higher in patients with diabetes mellitus (9.4 [4.9ā€“13.2] vs 4.8 [3.4ā€“9.8] Ī¼mol/L; P = .005) and in subjects with New York Heart Association functional class III or greater (7.0 [4.7ā€“14.8] vs 4.7 [3.4ā€“11.3] Ī¼mol/L; P = .02). Elevated TMAO, choline, and betaine levels were each associated with higher plasma N-terminal proā€“B-type natriuretic peptide (NT-proBNP) levels and more advanced left ventricular diastolic dysfunction, but not systolic dysfunction or inflammatory and endothelial biomarkers. Higher choline (hazard ratio [HR] 1.64, 95% CI 1.22ā€“2.20; P = .001), betaine (HR 1.51, 95% CI 1.10ā€“2.08; P = .01), and TMAO (HR 1.48, 95% CI 1.10ā€“1.96; P = .01) predicted increased risk for 5-year adverse clinical events (death/transplantation). Only higher TMAO levels predicted incident adverse clinical events independently from age, estimated glomerular filtration rate, mitral E/septal Ea, and NT-proBNP levels (HR 1.46, 95% CI 1.03ā€“2.14; P = .03). Conclusion: Elevated plasma TMAO, choline, and betaine levels are each associated with more advanced left ventricular diastolic dysfunction and portend poorer long-term adverse clinical outcomes in chronic systolic HF. However, only higher plasma TMAO was associated with poor prognosis after adjustment for cardiorenal indices

    Integrating cumulative context into computer games

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    In this paper, we describe a cumulative context computer game, where accumulated contextual information of the players ā€Ÿ activity levels, obtained through mobile sensors, is used to modify game state. Our implementation used a statistic-based, real-time version of the classic game of chess, where the statistics of the pieces depended on the activity of the users and the environment in which they performed the activity. Users found the game engaging and fun, and almost all of the participants altered their behaviors to enhance their performance in the game. This work provides a platform for further research into meaningful integration of cumulative context in games

    Project ATLANTA (ATlanta Land-use ANalysis: Temperature and Air quality): A Study of how the Urban Landscape Affects Meteorology and Air Quality Through Time

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    It is our intent through this investigation to help facilitate measures that can be Project ATLANTA (ATlanta Land-use ANalysis: applied to mitigate climatological or air quality Temperature and Air-quality) is a NASA Earth degradation, or to design alternate measures to sustain Observing System (EOS) Interdisciplinary Science or improve the overall urban environment in the future. investigation that seeks to observe, measure, model, and analyze how the rapid growth of the Atlanta. The primary objectives for this research effort are: 1) To In the last half of the 20th century, Atlanta, investigate and model the relationship between Atlanta Georgia has risen as the premier commercial, urban growth, land cover change, and the development industrial, and transportation urban area of the of the urban heat island phenomenon through time at southeastern United States. The rapid growth of the nested spatial scales from local to regional; 2) To Atlanta area, particularly within the last 25 years, has investigate and model the relationship between Atlanta made Atlanta one of the fastest growing metropolitan urban growth and land cover change on air quality areas in the United States. The population of the through time at nested spatial scales from local to Atlanta metropolitan area increased 27% between 1970 regional; and 3) To model the overall effects of urban and 1980, and 33% between 1980-1990 (Research development on surface energy budget characteristics Atlanta, Inc., 1993). Concomitant with this high rate of across the Atlanta urban landscape through time at population growth, has been an explosive growth in nested spatial scales from local to regional. Our key retail, industrial, commercial, and transportation goal is to derive a better scientific understanding of how services within the Atlanta region. This has resulted in land cover changes associated with urbanization in the tremendous land cover change dynamics within the Atlanta area, principally in transforming forest lands to metropolitan region, wherein urbanization has urban land covers through time, has, and will, effect consumed vast acreas of land adjacent to the city local and regional climate, surface energy flux, and air proper and has pushed the rural/urban fringe farther quality characteristics. Allied with this goal is the and farther away from the original Atlanta urban core. prospect that the results from this research can be An enormous transition of land from forest and applied by urban planners, environmental managers agriculture to urban land uses has occurred in the and other decision-makers, for determining how Atlanta area in the last 25 years, along with subsequent urbanization has impacted the climate and overal
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