3,342 research outputs found

    Characteristics of a turbulent boundary layer perturbed by spatially-impulsive dynamic roughness

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    Statistical and spectral analyses of the manipulation of a canonical zero pressure gradient turbulent boundary layer using static roughness and low-frequency dynamic roughness patches are presented. A shift of spectral energy away from the wall downstream of the roughness patch is observed. The dynamic roughness is shown to disrupt the structure of the boundary layer, while embedding its periodic signature in an extensive stretch of the downstream flow field

    Versatile toolbox for high throughput biochemical and functional studies with fluorescent fusion proteins

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    Fluorescent fusion proteins are widely used to study protein localization and interaction dynamics in living cells. However, to fully characterize proteins and to understand their function it is crucial to determine biochemical characteristics such as enzymatic activity and binding specificity. Here we demonstrate an easy, reliable and versatile medium/high-throughput method to study biochemical and functional characteristics of fluorescent fusion proteins. Using a new system based on 96-well micro plates comprising an immobilized GFP-binding protein (GFP-mulitTrap), we performed fast and efficient one-step purification of different GFP- and YFP-fusion proteins from crude cell lysate. After immobilization we determined highly reproducible binding ratios of cellular expressed GFP-fusion proteins to histone-tail peptides, DNA or selected RFP-fusion proteins. In particular, we found Cbx1 preferentially binding to di-and trimethylated H3K9 that is abolished by phosphorylation of the adjacent serine. DNA binding assays showed, that the MBD domain of MeCP2 discriminates between fully methylated over unmethylated DNA and protein-protein interactions studies demonstrate, that the PBD domain of Dnmt1 is essential for binding to PCNA. Moreover, using an ELISA-based approach, we detected endogenous PCNA and histone H3 bound at GFP-fusions. In addition, we quantified the level of H3K4me2 on nucleosomes containing different histone variants. In summary, we present an innovative medium/high-throughput approach to analyse binding specificities of fluroescently labeled fusion proteins and to detect endogenous interacting factors in a fast and reliable manner in vitro

    Multiple Reentrant Phase Transitions and Triple Points in Lovelock Thermodynamics

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    We investigate the effects of higher curvature corrections from Lovelock gravity on the phase structure of asymptotically AdS black holes, treating the cosmological constant as a thermodynamic pressure. We examine how various thermodynamic phenomena, such as Van der Waals behaviour, reentrant phase transitions (RPT), and tricritical points are manifest for U(1) charged black holes in Gauss-Bonnet and 3rd-order Lovelock gravities. We furthermore observe a new phenomenon of "multiple RPT" behaviour, in which for fixed pressure the small/large/small/large black hole phase transition occurs as the temperature of the system increases. We also find that when the higher-order Lovelock couplings are related in a particular way, a peculiar isolated critical point emerges for hyperbolic black holes and is characterized by non-standard critical exponents.Comment: 50 pages, 28 Figures v2: minor corrections, references adde

    Maternal urinary bisphenol a during pregnancy and maternal and neonatal thyroid function in the CHAMACOS study.

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    BackgroundBisphenol A (BPA) is widely used in the manufacture of polycarbonate plastic bottles, food and beverage can linings, thermal receipts, and dental sealants. Animal and human studies suggest that BPA may disrupt thyroid function. Although thyroid hormones play a determinant role in human growth and brain development, no studies have investigated relations between BPA exposure and thyroid function in pregnant women or neonates.ObjectiveOur goal was to evaluate whether exposure to BPA during pregnancy is related to thyroid hormone levels in pregnant women and neonates.MethodsWe measured BPA concentration in urine samples collected during the first and second half of pregnancy in 476 women participating in the CHAMACOS (Center for the Health Assessment of Mothers and Children of Salinas) study. We also measured free thyroxine (T4), total T4, and thyroid-stimulating hormone (TSH) in women during pregnancy, and TSH in neonates.ResultsAssociations between the average of the two BPA measurements and maternal thyroid hormone levels were not statistically significant. Of the two BPA measurements, only the one taken closest in time to the TH measurement was significantly associated with a reduction in total T4 (β = -0.13 µg/dL per log2 unit; 95% CI: -0.25, 0.00). The average of the maternal BPA concentrations was associated with reduced TSH in boys (-9.9% per log2 unit; 95% CI: -15.9%, -3.5%) but not in girls. Among boys, the relation was stronger when BPA was measured in the third trimester of pregnancy and decreased with time between BPA and TH measurements.ConclusionResults suggest that exposure to BPA during pregnancy is related to reduced total T4 in pregnant women and decreased TSH in male neonates. Findings may have implications for fetal and neonatal development

    Status Report on Principles of International and Human Rights Law Relevant to Climate Change

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    The report aims to provide high-level guidance on the legal issues to be analyzed by the ICJ on the advisory opinion request on climate change. The status report addresses (i) advisory proceedings before the ICJ, including the Court’s jurisdiction and procedure (Section II), and (ii) key legal principles relevant to the request for an advisory opinion, including principles of international environmental law and international human rights law (Section III). The report identified, in a non-exhaustive manner, key relevant principles of international environmental law, key relevant principles of international human rights law, and issues of intergenerational equities that apply to the questions posed to the ICJ. The status report is part of the Youth Climate Justice Handbook, organized by the World’s Youth for Climate Justice and the Pacific Students Fighting Climate Change. The Handbook, which will be launched in early May, consists of three parts: (1) The Summary for Policymakers, (2) The Legal Memorandum, and (3) the Status Report

    Electronic vs. Print Resources: A Survey of Perception, Usage and Preferences Among Central University Undergraduate Students

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    The study adopted a cross-sectional survey approach to examine the perception, usage and preferences of electronic and print resources among University Students. The study sought to determine the knowledge of students on electronic library resources, their value for electronic and print resources, ascertain the perceived usefulness, perceived ease of use, and intended use these resources. Results from the study indicated that majority 134(57.0%) of the respondents always preferred print resources format for their academic work while 101(43%) occasionally preferred the electronic resource format for academic work. The findings of the study are critical to the implementation of policies and procedures geared toward sensitizing students, faculty and other stakeholders to the benefits of increasing students’ knowledge and use of electronic library resources. The study is envisaged to aid in strategic planning and investments pertaining to these resources and provide recommendations to improve knowledge and use of these resources within university
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