1,908 research outputs found

    What’s a Federalist to Do? The Impending Clash Between Textualism and Federalism in State Congressional Redistricting Suits Under Article 1, Section 4

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    Nanofluids (NFs) are nanotechnology-based colloidal dispersion prepared by dispersing nanoparticles (NPs) in conventional liquids, as the base liquid. These advanced fluids have displayed potential to enhance the performance of conventional heat transfer fluids. This work aims at providing an insight to the field of NFs by investigating in detail the fabrication and evaluation of physico-chemical, thermo-physical and heat transfer characteristics of NFs for practical heat transfer applications. However, in order to utilize NFs as heat transfer fluids in real applications there are some challenges to overcome. Therefore, our goal is not only to optimize the thermo-physical properties of NFs with the highest thermal conductivity (TC) and minimal impact of NPs on viscosity, but also on preparing NFs with good stability and the best heat transfer performance. In the first stage, detailed studies were carried out to engineer NFs with good stability and optimal thermo-physical properties. In this work we investigated the most important factors, and the dependence of thermo-physical properties of NFs, including NP composition and concentration, NF stability, surface modifiers, particle size (NP size and particle with micron size), NF preparation method (two-step vs one-step method) and base liquid was studied. We also demonstrated, for the first time, the role of crystal structure, exemplified by alpha- and beta- SiC particles, on thermo-physical properties of NFs. For these purposes several NFs were fabricated using different nanostructured materials and various base liquids by one-step and two-step methods. An optimization procedure was designed to keep a suitable control in order to reach the ultimate aim where several stages were involved to check the desired characteristics of each NF system. Among several NFs systems studied in the first stage evaluation, a particular NF system with 9 wt% concentration, engineered by dispersing SiC NPs with alpha- crystal structure in water/ethylene glycol as based liquid exhibited the optimal thermo-physical properties. This NF was the only case which could pass the all criteria involved in the optimization procedure by exhibiting good stability, TC enhancements of ~20% with only 14% increase in viscosity at 20 oC. Therefore, this engineered NF was considered for next phase evaluation, where heat transfer coefficient (HTC) tests were designed and carried out to evaluate the thermal transport property of the selected alpha- SiC NF. A HTC enhancement of 5.5% at equal pumping power, as realistic comparison criteria, was obtained indicating the capability of this kind of NFs to be used in industrial heat transfer applications. These findings are among the few studies in the literature where the heat transfer characteristics of the NFs were noticeable, reproducible and based on a realistic situation with capability of commercializing as effective heat transfer fluid.  QC 20140416Nanohe

    Peptidases and the Renin-Angiotensin System: The Alternative Angiotensin-(1-7) Cascade

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    The renin-angiotensin system (RAS) constitutes a key hormonal system in the physiological regulation of blood pressure via peripheral and central mechanisms. Dysregulation of the RAS is considered a major factor in the development of cardiovascular pathologies, and pharmacologic blockades of this system by the inhibition of angiotensin-converting enzyme (ACE) or antagonism of the angiotensin type 1 receptor (AT1R) are effective therapeutic regimens. The RAS is now defined as a system composed of different angiotensin peptides with diverse biological actions mediated by distinct receptor subtypes. The classic RAS comprises the ACE-Ang II-AT1R axis that promotes vasoconstriction, water intake, sodium retention and increased oxidative stress, fibrosis, cellular growth, and inflammation. The nonclassical or alternative RAS is composed primarily of the ACE2-Ang-(1-7)-AT7R pathway that opposes the Ang II-AT1R axis. In lieu of the complex aspects of this system, the current review assesses the enzymatic cascade of the alternative Ang-(1-7) axis of the RAS

    A randomised controlled intervention trial evaluating the efficacy of a Mediterranean dietary pattern on cognitive function and psychological wellbeing in healthy older adults: the MedLey study

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    Background: The incidence of age-related cognitive decline is rising considerably around the world. There is evidence from a number of recent cross-sectional and prospective studies indicating positive associations between the Mediterranean dietary pattern (MedDiet) and improved cognitive outcomes among the elderly including, reduced age-related cognitive decline and enhanced age-related cognitive performance. However, to date no study has validated these associations in healthy older adult populations (≥65 years and above) with randomised evidence. The main aim of the present study is to provide justified evidence regarding the efficacy of a MedDiet approach to safely reduce the onset of cognitive decline, and promote optimal cognitive performance among healthy older adults using rigorous, randomised intervention methodology. Methods/Design: MedLey is a 6-month, randomised controlled 2-cohort parallel group intervention trial, with initial assessment at baseline and repeated every three months. A sample of 166 healthy Australian men and women aged 65 years and above, with normal cognitive function and proficient in English language were recruited from metropolitan Adelaide, South Australia for the study. Participants randomly allocated to the experimental group are required to maintain an intervention dietary pattern based from the traditional Cretan MedDiet (i.e. vegetables, fruits, olive oil, legumes, fish, whole grain cereals, nuts and seeds and low consumption of processed foods, dairy products, red meat and vegetable oils) for six months, while those participants allocated to the control group are asked to maintain their customary lifestyle and diet. The primary outcome of interest is the quantitative difference in age-related cognitive performance, as measured by latent variables (cognitive constructs) sensitive to normal ageing and diet (i.e. speed of processing, memory, attention, executive functions, visual spatial and visuomotor ability). Secondary outcomes include change in biomarkers of inflammation, oxidative stress, lipid metabolism, glucose, insulin, blood flow velocity, and psychological well-being factors (i.e. stress, sleep, anxiety, depression). Discussion: To our knowledge this will be one of the first randomised clinical trials worldwide to provide evidence for the cause-effect relationship between the MedDiet and age-related cognitive function in a healthy older adult population (≥65 years and over).Alissa Knight, Janet Bryan, Carlene Wilson, Jonathan Hodgson and Karen Murph

    Probing the dynamics of O-GlcNAc glycosylation in the brain using quantitative proteomics

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    The addition of the monosaccharide beta-N-acetyl-D-glucosamine to proteins (O-GlcNAc glycosylation) is an intracellular, post-translational modification that shares features with phosphorylation. Understanding the cellular mechanisms and signaling pathways that regulate O-GlcNAc glycosylation has been challenging because of the difficulty of detecting and quantifying the modification. Here, we describe a new strategy for monitoring the dynamics of O-GlcNAc glycosylation using quantitative mass spectrometry-based proteomics. Our method, which we have termed quantitative isotopic and chemoenzymatic tagging (QUIC-Tag), combines selective, chemoenzymatic tagging of O-GlcNAc proteins with an efficient isotopic labeling strategy. Using the method, we detect changes in O-GlcNAc glycosylation on several proteins involved in the regulation of transcription and mRNA translocation. We also provide the first evidence that O-GlcNAc glycosylation is dynamically modulated by excitatory stimulation of the brain in vivo. Finally, we use electron-transfer dissociation mass spectrometry to identify exact sites of O-GlcNAc modification. Together, our studies suggest that O-GlcNAc glycosylation occurs reversibly in neurons and, akin to phosphorylation, may have important roles in mediating the communication between neurons

    A Comparative Astrochemical Study Of The High-Mass Protostellar Objects NGC 7538 IRS 9 and IRS 1

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    We report the results of a spectroscopic study of the high-mass protostellar object NGC 7538 IRS 9 and compare our observations to published data on the nearby object NGC 7538 IRS 1. Both objects originated in the same molecular cloud and appear to be at different points in their evolutionary histo- ries, offering an unusual opportunity to study the temporal evolution of envelope chemistry in objects sharing a presumably identical starting composition. Observations were made with the Texas Echelon Cross Echelle Spectrograph (TEXES), a sensitive, high spectral resolution (R = {\lambda}/{\Delta}{\lambda} \simeq 100,000) mid-infrared grating spectrometer. Forty-six individual lines in vibrational modes of the molecules C2H2, CH4, HCN, NH3 and CO were detected, including two isotopologues (13CO, 12C18O) and one combination mode ({\nu}4 + {\nu}5 C2H2). Fitting synthetic spectra to the data yielded the Doppler shift, excitation temperature, Doppler b parameter, column density and covering factor for each molecule observed; we also computed column density upper limits for lines and species not detected, such as HNCO and OCS. We find differences among spectra of the two objects likely attributable to their differing radiation and thermal environments. Temperatures and column densities for the two objects are generally consistent, while the larger line widths toward IRS 9 result in less saturated lines than those toward IRS 1. Finally, we compute an upper limit on the size of the continuum-emitting region (\sim2000 AU) and use this constraint and our spectroscopy results to construct a schematic model of IRS 9.Comment: 23 pages, 15 figures, 6 tables; accepted for publication in Ap

    Functional and Transcriptional Characterization of Human Embryonic Stem Cell-Derived Endothelial Cells for Treatment of Myocardial Infarction

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    BACKGROUND: Differentiation of human embryonic stem cells into endothelial cells (hESC-ECs) has the potential to provide an unlimited source of cells for novel transplantation therapies of ischemic diseases by supporting angiogenesis and vasculogenesis. However, the endothelial differentiation efficiency of the conventional embryoid body (EB) method is low while the 2-dimensional method of co-culturing with mouse embryonic fibroblasts (MEFs) require animal product, both of which can limit the future clinical application of hESC-ECs. Moreover, to fully understand the beneficial effects of stem cell therapy, investigators must be able to track the functional biology and physiology of transplanted cells in living subjects over time. METHODOLOGY: In this study, we developed an extracellular matrix (ECM) culture system for increasing endothelial differentiation and free from contaminating animal cells. We investigated the transcriptional changes that occur during endothelial differentiation of hESCs using whole genome microarray, and compared to human umbilical vein endothelial cells (HUVECs). We also showed functional vascular formation by hESC-ECs in a mouse dorsal window model. Moreover, our study is the first so far to transplant hESC-ECs in a myocardial infarction model and monitor cell fate using molecular imaging methods. CONCLUSION: Taken together, we report a more efficient method for derivation of hESC-ECs that express appropriate patterns of endothelial genes, form functional vessels in vivo, and improve cardiac function. These studies suggest that hESC-ECs may provide a novel therapy for ischemic heart disease in the future

    Net neutrality discourses: comparing advocacy and regulatory arguments in the United States and the United Kingdom

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    Telecommunications policy issues rarely make news, much less mobilize thousands of people. Yet this has been occurring in the United States around efforts to introduce "Net neutrality" regulation. A similar grassroots mobilization has not developed in the United Kingdom or elsewhere in Europe. We develop a comparative analysis of U.S. and UK Net neutrality debates with an eye toward identifying the arguments for and against regulation, how those arguments differ between the countries, and what the implications of those differences are for the Internet. Drawing on mass media, advocacy, and regulatory discourses, we find that local regulatory precedents as well as cultural factors contribute to both agenda setting and framing of Net neutrality. The differences between national discourses provide a way to understand both the structural differences between regulatory cultures and the substantive differences between policy interpretations, both of which must be reconciled for the Internet to continue to thrive as a global medium
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