1,127 research outputs found
A Different Level of Caring: Navigating the Intersections of Perception of Care in Teaching
This study sought to predict teacherâs perceptions of caring. We surveyed 457 educators using the Caring Abilities Inventory (Nkongho, 1990). Due to the ever increasing diversity of American classrooms, it is critical to determine how to best recognize, recruit, and prepare the next generation of teachers. Findings indicated differences in caring among gender and race. Implications for teacher preparation programs could be a need to gain insight into gendered and racial notions of care
Nuclear Reaction Rates in a Plasma
The problem of determining the effects of the surrounding plasma on nuclear
reaction rates in stars is formulated ab initio, using the techniques of
quantum statistical mechanics. We derive a result that expresses the complete
effects of Coulomb barrier penetration and of the influence of the surrounding
plasma in terms of matrix elements of well defined operators. We find that
possible "dynamical screening" effects that have been discussed in the
literature are absent. The form of our results suggests that an approach that
relies on numerical calculations of the correlation functions in a classical
Coulomb gas, followed by construction of an effective two body potential and a
quantum barrier penetration calculation, will miss physics that is as important
as the physics that it includes.Comment: 66 pages, revtex, Errors Fixed, Explanation Adde
Sandfly saliva of Lutzomyia ovallesi (Diptera: Psychodidae) as a possible marker for the transmission of Leishmania in Venezuela Andes region
Background & objectives: The saliva of the Phlebotominae is highly immunogenic to the vertebrate host and isa determining factor in the Leishmania infection. The aim of this work was to study the saliva of Lutzomyiaovallesi as a possible risk marker for the transmission of Leishmania.Methods: Two populations of L. ovallesi from different geographical areas and subjected to different environmentalconditions were compared by geometric morphometry of the wings, by protein profile analysis of salivary glandsand by assessing the presence of anti-saliva protein in human sera confronted with laboratory L. ovallesi saliva.Results: The results showed differences in the isometric size and structure of the wings but no allometric effects.Protein profiles of salivary glands of both the L. ovallesi populations studied were found to be similar, based on11 protein bands with molecular weights ranging from 16 to 99 kDa. Anti-saliva antibodies were present inhuman sera, but human sera infected and uninfected with leishmaniasis could not be differentiated.Interpretation & conclusion: We conclude that the saliva of laboratory-reared L. ovallesi is representative ofthat of the wild population. It is suggested to study the presence of anti-saliva antibodies in other species ofsandflies and mosquitoe
Anomalous reactivity of supported V2O5 nanoparticles for propane oxidative dehydrogenation: influence of the vanadium oxide precursor
Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugĂ€nglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.The oxidative dehydrogenation (ODH) of propane to propylene by supported vanadia catalysts has received much attention in recent years, but different reactivity trends have been reported for this catalytic reaction system. In the present investigation, the origin of these differing trends are investigated with synthesis of supported V/SiO2, V/TiO2, and V/Al2O3 catalysts prepared with three different vanadium oxide precursors (2-propanol/vanadyl triisopropoxide [VO(O-Pri)3] (VTI), oxalic acid/ammonium metavanadate [NH4VO3] (AMV), and toluene/vanadyl acetylacetonate [VO(C5H7O2)2] (VAA)) in order to elucidate the influence of the precursor on supported vanadia phase and propane ODH activity. In situ Raman spectroscopy revealed that the choice of vanadium precursor does not affect the dispersion of the supported vanadium oxide phase below 4 V nmâ2 (0.5 monolayer coverage), where only isolated and oligomeric surface VO4 species are present, and only the AMV precursor favors crystalline V2O5 nanoparticle (NP) formation below monolayer coverage (8 V nmâ2). The propane ODH specific reactivity trend demonstrated that there is no significant difference in TOF for the isolated and oligomeric surface VO4 sites. Surprisingly, V2O5 NPs in the âŒ1â2 nm range exhibit anomalously high propane ODH TOF values for the supported vanadia catalysts. This was found for all supported vanadium oxide catalysts examined. This comparative study with different V-precursors and synthesis methods and oxide supports finally resolves the debate in the catalysis literature about the dependence of TOF on the surface vanadium density that is related to the unusually high reactivity of small V2O5 NPs.DFG, SFB 546, Struktur, Dynamik und ReaktivitĂ€t von Ăbergangsmetalloxid-Aggregate
Environmental and Economic Water Management in Shale Gas Extraction
This paper introduces a comprehensive study of the Life Cycle Impact Assessment (LCIA) of water management in shale gas exploitation. First, we present a comprehensive study of wastewater treatment in the shale gas extraction, including the most common technologies for the pretreatment and three different desalination technologies of recent interest: Single and Multiple-Effect Evaporation with Mechanical Vapor Recompression and Membrane Distillation. The analysis has been carried out through a generic Life Cycle Assessment (LCA) and the ReCiPe metric (at midpoint and endpoint levels), considering a wide range of environmental impacts. The results show that among these technologies Multiple-Effect Evaporation with Mechanical Vapor Recompression (MEE-MVR) is the most suitable technology for the wastewater treatment in shale gas extraction, taking into account its reduced environmental impact, the high water recovery compared to other alternatives as well as the lower cost of this technology. We also use a comprehensive water management model that includes previous results that takes the form of a new Mixed-Integer Linear Programming (MILP) bi-criterion optimization model to address the profit maximization and the minimization Life Cycle Impact Assessment (LCIA), based on its results we discuss the main tradeoffs between optimal operation from the economic and environmental points of view.This project has received funding from the Spanish «Ministerio de EconomĂa, Industria y Competitividad» under the projects CTQ2016-77968-C3-1-P and CTQ2016-77968-C3-2-P (FEDER, UE)
La Actualidad de âRealidad y Serâ en Xavier Zubiri
Nuestro propĂłsito es examinar quĂ© entiende Xavier ZubirĂ por âRealidad y Serâ en su obra Estructura DinĂĄmica de la Realidad con el objetivo de determinar su alcance y su consistencia. Para ello vamos a analizar dicha concepciĂłn del Ser desde una lectura tomista, luego analizaremos realidad y Ser siguiendo al efecto una lectura scotista, despuĂ©s haremos una reflexiĂłn de la actualidad de Zubiri a partir del pensamiento de Juan David GarcĂa Bacca y Gilles Deleuze y Felix Guattari y finalmente, examinaremos quĂ© nos depara la orientaciĂłn de estos conceptos teniendo presente los desafĂos que presenta la metafĂsica en la actualidad
Mechanochemically synthesized Pb-free halide perovskite-based Cs2AgBiBr6âCuâRGO nanocomposite for photocatalytic CO2 reduction
Pb-based halide perovskites have recently showed great potential in various applications such as solar cells, optoelectronics and photocatalysis. Despite their high performance, the Pb2+ toxicity along with poor stability hinders long term applications in photocatalysis. Herein, we report mechanochemically prepared Pb-free Cs2AgBiBr6 double perovskite nanoplates and their heterostructure with Cu-loaded reduced graphene oxide (CuâRGO) for gas-phase photocatalytic CO2 reduction using water vapor as the proton source in the absence of a hole scavenger. The resulting Cs2AgBiBr6âCuâRGO nanocomposite shows significant photocatalytic activity of 10.7 (±0.6) ÎŒmol CH4 gâ1 hâ1, 1.9 (±0.3) ÎŒmol CO gâ1 hâ1 and 1.0 (±0.2) ÎŒmol H2 gâ1 hâ1, with a CH4 selectivity of 93.0 (±0.5)% on an electron basis with 1 sun and a remarkable apparent quantum efficiency of 0.89 (±0.21)% at 590 nm. A further 32% enhancement in photocatalytic activity on an electron basis is achieved when the light intensity is doubled (2 suns). The high performance was attributed to their improved charge separation and suppressed electronâhole recombination, along with extended visible light absorption, better stability in a humid environment and improved CO2 adsorption. These findings support Cs2AgBiBr6 as a potential Pb-free alternative to conventional halide perovskites for photocatalytic solar-to-fuel conversion and CO2 utilization
Cardiovascular disease risk assessment in patients with familial Mediterranean fever related renal amyloidosis
Chronic inflammation and proteinuria is a risk factor for cardiovascular disease (CVD) in patients with chronic kidney diseases and rheumatologic disorders. Our aim was to investigate the CVD events (CVDEs) and survival between the patients with FMF-related AA amyloidosis and glomerulonephropathies (GN) to define possible predictors for CVDEs. A prospective follow-up study with FMF-amyloidosis and glomerulonephropathy (GN) was performed and patients were followed for CVDEs. Flow-mediated dilatation (FMD), FGF-23, serum lipid, hsCRP levels, BMI and HOMA were assessed. A Cox regression analysis was performed to evaluate the risk factors for CVDEs. There were 107 patients in the FMF-amyloidosis group and 126 patients with GN group. Forty-seven CVDEs were observed during the 4.2-years follow up; all 28 patients in the FMF-amyloidosis group and 14/19 patients with GN developed CVDEs before the age of 40 (pâ=â0.002). CVD mortality was 2.8 times higher (95% CI 1.02â7.76) in patients with FMF-amyloidosis. Across both groups, FMD and FGF23 (pâ<â0.001) levels were independently associated with the risk of CVDEs. Patients with FMF-amyloidosis are at increased risk of early CVDEs with premature mortality age. FGF 23, FMD and hsCRP can stratify the risk of early CVD in patients with FMF-related AA amyloidosis
Listeriolysin O Is Strongly Immunogenic Independently of Its Cytotoxic Activity
The presentation of microbial protein antigens by Major Histocompatibility Complex (MHC) molecules is essential for the development of acquired immunity to infections. However, most biochemical studies of antigen processing and presentation deal with a few relatively inert non-microbial model antigens. The bacterial pore-forming toxin listeriolysin O (LLO) is paradoxical in that it is cytotoxic at nanomolar concentrations as well as being the source of dominant CD4 and CD8 T cell epitopes following infection with Listeria monocytogenes. Here, we examined the relationship of LLO toxicity to its antigenicity and immunogenicity. LLO offered to antigen presenting cells (APC) as a soluble protein, was presented to CD4 T cells at picomolar to femtomolar concentrations- doses 3000â7000-fold lower than free peptide. This presentation required a dose of LLO below the cytotoxic level. Mutations of two key tryptophan residues reduced LLO toxicity by 10â100-fold but had no effect on its presentation to CD4 T cells. Thus there was a clear dissociation between the cytotoxic properties of LLO and its very high antigenicity. Presentation of LLO to CD8 T cells was not as robust as that seen in CD4 T cells, but still occurred in the nanomolar range. APC rapidly bound and internalized LLO, then disrupted endosomal compartments within 4 hours of treatment, allowing endosomal contents to access the cytosol. LLO was also immunogenic after in vivo administration into mice. Our results demonstrate the strength of LLO as an immunogen to both CD4 and CD8 T cells
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