1,290 research outputs found

    Estimation of Sounding Uncertainty from Measurements of Water Mass Variability

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    Analysis techniques are introduced that allow for estimation of potential sounding uncertainty due to water mass variability from reconnaissance campaigns in which oceanographic parameters are measured at a high temporal and spatial resolution. The analysis techniques do not require sounding data, thus analyses can be tailored to match any survey system; this allows for pre-analysis campaigns to optimize survey instrumentation and sound speed profiling rates such that a desired survey specification can be maintained. Additionally, the output of the analysis methods can potentially provide a higher fidelity estimation of sounding uncertainty due to water mass variability than uncertainty models in common use.Se presentan análisis técnicos que permiten una estimación de posibles incertidumbres en los sondeos, debidas a la variabilidad de la masa de agua, procedentes de campañas de reconocimiento en las que los parámetros oceanográficos son medidos con una resolución temporal y espacial elevada. Los análisis técnicos no requieren los datos de sondeos, así pues dichos análisis pueden adaptarse a cualquier sistema hidrográfico. Esto permite campañas de análisis previos para optimizar la instrumentación hidrográfica y los niveles de descripción de la velocidad del sonido, para que pueda mantenerse una especificación hidrográfica deseada. Además, el resultado de los métodos analíticos puede proporcionar potencialmente una estimación de la fidelidad de las incertidumbres en los sondeos, debidas a una variabilidad de la masa de agua mayor que la de los modelos de incertidumbres que se utilizan corrientemente.Des techniques d’analyse sont introduites afin de permettre l’estimation de l’incertitude potentielle des sondes due à la variabilité de la masse d’eau à partir de campagnes de reconnaissance dans lesquelles les paramètres océanographiques sont mesurés avec une haute résolution temporelle et spatiale. Les techniques d’analyse ne nécessitant pas de données de sondes, les analyses peuvent donc être ajustées pour s’adapter à tout système de levés ; ceci permet aux campagnes de pré-analyse d’optimiser l’instrumentation hydrographique ainsi que les niveaux de profilage de la vitesse du son de manière à conserver une spécification de levé souhaitée. En outre, le résultat des méthodes d’analyse peut potentiellement fournir une estimation à plus haute fidélité, en ce qui concerne les incertitudes des sondes du fait de la variabilité de la masse d’eau, que les modèles d’incertitude en usage

    Comparing Cardiac Dynamics between Neonatal and Adult Rats

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    Background: Cardiovascular physiology studies have been largely limited to adult models; yet, significant developmental differences exist between the immature and adult heart. The field of pediatric research has largely been limited to immortalized cardiomyocyte cell lines, which lack physiologically relevant action potentials, and primary neonatal myocytes that have a limited life span and lack physiologically relevant automaticity. As a result, our understanding of developmental changes in ion channel expression, t-tubule development, and excitation-contraction coupling have been deduced from 2D simplified cell models. To fully understand cardiac development from neonate to adult, a physiologically-relevant 3D whole heart model is needed to monitor dynamic changes in electrical activity and excitation-contraction coupling. Objective: This study aimed to establish a pediatric research model to monitor developmental changes in electrical activity and excitation-contraction coupling, using both imaging tools and electrocardiograms. Methods/Design: Sprague-Dawley rat hearts (3 days – adult) were excised, the aorta was cannulated, and then the heart was transferred to a temperature-controlled constant pressure Langendorff-perfusion system. The perfusate was supplemented with 10 mM blebbistatin to reduce motion artifacts by mechanically uncoupling electrical and mechanical activity. Calcium (50 mg Rhod2-AM) and voltage (62 mg RH237) sensitive dyes were used to stain the heart, signals were acquired using a sCMOS camera (Andor, Zyla 4.2 Plus; \u3e500fps). Electrocardiograms were monitored continuously (lead II configuration) and analyzed using ecgAUTO. Results/Discussion: Initial results showed that compared to adult cohorts, neonatal rats displayed a longer action potential duration (APD80: adult= 85.9ms, neonatal=95.5ms, p=0.026), and a steeper Tau Fall (adults: 33.8ms, neonatal 69.9ms, p=.012) which are likely associated with delayed Ito expression. Calcium handling was also slower in the neonatal hearts (Cad80: Adults: 128.9ms, neonatal=138.8, p=.004), likely due to immature calcium handling and less robust calcium-induced calcium release. The developing excitation-contraction coupling machinery will be further probed using pharmacological tools to elucidate underlying mechanisms; and the newly developed pediatric model will be used for toxicological screening. Acknowledgements: The authors gratefully acknowledge Daniel McInerney for technical assistance. This work was supported by the National Institutes of Health (R00ES023477, R01HL139472), Children’s Research Institute and Children’s National Heart Institute

    Theology, News and Notes - Vol. 26, No. 03

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    Theology News & Notes was a theological journal published by Fuller Theological Seminary from 1954 through 2014.https://digitalcommons.fuller.edu/tnn/1068/thumbnail.jp

    Geographic and facility variation in initial use of non-tunneled catheters for incident maintenance hemodialysis patients

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    Abstract Background Non-tunneled (temporary) hemodialysis catheters (NTHCs) are the least-optimal initial vascular access for incident maintenance hemodialysis patients yet little is known about factors associated with NTHC use in this context. We sought to determine factors associated with NTHC use and examine regional and facility-level variation in NTHC use for incident maintenance hemodialysis patients. Methods We analyzed registry data collected between January 2001 and December 2010 from 61 dialysis facilities within 12 geographic regions in Canada. Multi-level models and intra-class correlation coefficients were used to evaluate variation in NTHC use as initial hemodialysis access across facilities and geographic regions. Facility and patient characteristics associated with the lowest and highest quartiles of NTHC use were compared. Results During the study period, 21,052 patients initiated maintenance hemodialysis using a central venous catheter (CVC). This included 10,183 patients (48.3 %) in whom the initial CVC was a NTHC, as opposed to a tunneled CVC. Crude variation in NTHC use across facilities ranged from 3.7 to 99.4 % and across geographic regions from 32.4 to 85.1 %. In an adjusted multi-level logistic regression model, the proportion of total variation in NTHC use explained by facility-level and regional variation was 40.0 % and 34.1 %, respectively. Similar results were observed for the subgroup of patients who received greater than 12 months of pre-dialysis nephrology care. Patient-level factors associated with increased NTHC use were male gender, history of angina, pulmonary edema, COPD, hypertension, increasing distance from dialysis facility, higher serum phosphate, lower serum albumin and later calendar year. Conclusions There is wide variation in NTHC use as initial vascular access for incident maintenance hemodialysis patients across facilities and geographic regions in Canada. Identifying modifiable factors that explain this variation could facilitate a reduction of NTHC use in favor of more optimal initial vascular access

    HDAC3 is a molecular brake of the metabolic switch supporting white adipose tissue browning.

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    White adipose tissue (WAT) can undergo a phenotypic switch, known as browning, in response to environmental stimuli such as cold. Post-translational modifications of histones have been shown to regulate cellular energy metabolism, but their role in white adipose tissue physiology remains incompletely understood. Here we show that histone deacetylase 3 (HDAC3) regulates WAT metabolism and function. Selective ablation of Hdac3 in fat switches the metabolic signature of WAT by activating a futile cycle of de novo fatty acid synthesis and β-oxidation that potentiates WAT oxidative capacity and ultimately supports browning. Specific ablation of Hdac3 in adipose tissue increases acetylation of enhancers in Pparg and Ucp1 genes, and of putative regulatory regions of the Ppara gene. Our results unveil HDAC3 as a regulator of WAT physiology, which acts as a molecular brake that inhibits fatty acid metabolism and WAT browning.Histone deacetylases, such as HDAC3, have been shown to alter cellular metabolism in various tissues. Here the authors show that HDAC3 regulates WAT metabolism by activating a futile cycle of fatty acid synthesis and oxidation, which supports WAT browning

    Opa vs Oper: Neutralization of /?/ and unstressed /a/ contrast in a perception and production study

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    The present study examined differences in production and perception of the German vowels /a/ and /?/ in word-final, unstressed position. In the first experiment, 3 male and 3 female speakers produced minimal pairs embedded in meaningful sentences and varied in prosodic environment. In the second experiment, the minimal pairs were extracted from the context and presented to 44 listeners for a forced-choice identification task. Results showed a better-than-chance performance that was, however, mainly driven by one male speaker. Temporal and spectral measures confirmed that only this speaker produced an acoustic difference between /a/ and /?/

    Conceptual learning : the priority for higher education

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    The common sense notion of learning as the all-pervasive acquisition of new behaviour and knowledge, made vivid by experience, is an incomplete characterisation, because it assumes that the learning of behaviour and the learning of knowledge are indistinguishable, and that acquisition constitutes learning without reference to transfer. A psychological level of analysis is used to argue that conceptual learning should have priority in higher education
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