2,931 research outputs found

    Neurological sequelae of lightning injury

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    Man has been exposed to lightning ever since his appearance on earth. This is particularly so when he moves about in open spaces with the risk of being struck by lightning being about 30 times greater in rural areas than in cities. Lightning strikes are not rare and fortunately, the majority survive with no long term sequelae. Any part of the peripheral or central nervous system may be involved. Of crucial importance are the points of contact, and therefore the path of current flow.peer-reviewe

    L-lactate reduces ischemic white matter injury and modulates HCA1 oligodendrocyte expression in an in vivo mouse model of focal ischemia

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    L-lactate is a metabolite that is oxidized preferentially to glucose under conditions of high metabolic stress. The discovery and localization of the lactate receptor HCA1 in various brain regions suggests that lactate is additionally an important signaling molecule in the brain. Lactate is neuroprotective in various ischemia paradigms, reduces axonal injury in vitro and is avidly utilized by oligodendrocytes (OLs). The protective potential of L-lactate to reduce white matter (WM) injury in a mouse stroke model was investigated.N/

    The Job Crafting Questionnaire: A new scale to measure the extent to which employees engage in job crafting.

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    Empirical research on employee job crafting is scarce, probably because until recently scales with which the construct can be reliably and validly measured were not available. Although a general scale has recently been developed, the cognitive component of job crafting was omitted. The aim of the present study was to address this gap by developing and validating the 15-item Job Crafting Questionnaire (JCQ). The sample consisted of 334 employees who completed a battery of questionnaires, including the JCQ. Exploratory and confirmatory factor analyses both supported a three-factor structure that reflected the task, relational, and cognitive forms of job crafting originally presented by Wrzesniewski and Dutton (2001). Convergent analyses showed the JCQ correlated positively with indices of proactive behaviour (i.e., organisational citizenship behaviour, strengths use, and self-concordant goal setting), and positive work functioning (i.e., job satisfaction, work contentment, work enthusiasm, and positive affect). These analyses also showed the measure correlated inversely with negative affect. Reliability analyses indicated the measure has high internal consistency. Together, the analyses supported the reliability and validity of the JCQ and it shows good promise as a measure to progress research on job crafting.“Permission to use scale: The Job Crafting Questionnaire (JCQ) may be used for research as long as proper credit is given. Permission is not needed to use the JCQ and requests to use the scales will not be answered on an individual basis because permission is granted here. This article should be used as the citation for the JCQ, and this note provides evidence that permission to use the scale is granted.

    Fiscal consolidation in a low inflation environment: pay cuts versus lost jobs

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    We construct a model of a monetary union to study fiscal consolidation in the Periphery of the euro area, through cuts in public sector wages or hiring when the nominal interest rate is constrained at its lower bound. Consolidation induces a positive wealth effect that increases demand, as well as a reallocation of workers towards the private sector, which together boost private activity. However, in a low inflation environment, demand is suppressed and the private sector is not able to absorb the additional workers. Comparing the two instruments, cuts in public hiring increase unemployment persistently in this environment, while wage cuts reduce it. Regions with higher mobility of labour between the two sectors are able to consolidate more effectively. Price flexibility is also key at the zero lower bound: for a higher degree of price rigidity in the Periphery, consolidation becomes harder to achieve. Consolidations can be self-defeating when the public good is productive, or a complement to private consumption

    A study on the development of scaffold fabrication using citric acid polyester – nanohydroxyapatite composite

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    ABSTRACT. Nano hydroxyapatite (n-HAp) and its composites have shown a great development in the field of tissue regeneration and in controlled drug delivery due to its good biocompatibility and bioactivity behavior. Furthermore, HAp-based nanocomposites enhance mechanical properties. These synthetic HAp nanocomposites can also be tailored to fabricate scaffold with controlled porosity which facilitate the growth of the cell in the field of tissue engineering. In this paper, we focus on the synthesis of nano hydroxyapatite (n-HAp) by sol-gel method. The synthesized nano powders were calcined at 500 oC and characterized by FT-IR, XRD and TEM. We have also described the synthesis of citric acid-based polyester by melt polycondensation method without adding catalyst. The monomers used were citric acid, 1,6-hexane diol and sebacic acid. The corresponding synthesized n-HAp/polyester composite have potential application in soft tissue engineering. The structures of polyester and its nanocomposite were studied by FT-IR and 1H NMR spectral studies. The thermal and mechanical properties of polyester, composites and cytotoxicity activity (MTT assay) using vero cells were also studied. Porous scaffold of the nano HAp/Polyester was fabricated by solvent-casting particulate leaching technique which is useful in the development of tissue engineering applications. SEM and TEM studies were carried out for nano HAp, polyester, composites and scaffold.   KEY WORDS: Cytotoxicity, Polycondensation, Sol-gel, Solvent-casting, Tissue engineering Bull. Chem. Soc. Ethiop. 2022, 36(4), 923-934.                                                                DOI: https://dx.doi.org/10.4314/bcse.v36i4.17                                                     &nbsp

    The nascent coffee ring with arbitrary droplet contact set: an asymptotic analysis

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    We consider the effect of droplet geometry on the early-stages of coffee ring formation during the evaporation of a thin droplet with an arbitrary simple, smooth, pinned contact line. We perform a systematic matched asymptotic analysis of the small-capillary number, large-solutal Peclet number limit for two evaporative models: a kinetic model, in which the evaporative flux is constant across the droplet, and a diffusive model, in which the evaporative flux is singular at the contact line. For both evaporative models, solute is transported to the contact line by a capillary flow while, local to the contact line, solute diffusion counters advection. The resulting interplay leads to the formation of the nascent coffee ring. By exploiting a coordinate system embedded in the contact line, we solve explicitly the local leading-order problem, deriving a similarity profile (in the form of a gamma distribution) that describes the coffee ring profile in its early stages. Notably, the ring characteristics change due to the concomitant asymmetry in the shape of the droplet free surface, the evaporative flux (in the diffusive evaporative regime) and the mass flux into the contact line. We utilize the asymptotic model to determine the effects of geometry on the growth of the coffee ring for a droplet with an elliptical contact set. Our results offer mechanistic insight into the effect of contact-line curvature on the development of the coffee-ring from deposition up to jamming of the solute; moreover our model predicts when finite concentration effects become relevant

    Excitonic coupling dominates the homogeneous photoluminescence excitation linewidth in semicrystalline polymeric semiconductors

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    We measure the homogeneous excitation linewidth of regioregular poly(3-hexylthiophene), a model semicrystalline polymeric semiconductor, by means of two-dimensional coherent photoluminescence excitation spectroscopy. At a temperature of 8\,K, we find a linewidth that is always ≳110\gtrsim 110\,meV full-width-at-half-maximum, which is a significant fraction of the total linewidth. It displays a spectral dependence and is minimum near the 0--0 origin peak. We interpret this spectral dependence of the homogeneous excitation linewidth within the context of a weakly coupled aggregate model.Comment: 13 pages, 4 figures, Supplementary Materia

    A prototypical model for tensional wrinkling in thin sheets

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    The buckling and wrinkling of thin films has recently seen a surge of interest among physicists, biologists, mathematicians and engineers. This has been triggered by the growing interest in developing technologies at ever decreasing scales and the resulting necessity to control the mechanics of tiny structures, as well as by the realization that morphogenetic processes, such as the tissue-shaping instabilities occurring in animal epithelia or plant leaves, often emerge from mechanical instabilities of cell sheets. While the most basic buckling instability of uniaxially compressed plates was understood by Euler more than 200 years ago, recent experiments on nanometrically thin (ultrathin) films have shown significant deviations from predictions of standard buckling theory. Motivated by this puzzle, we introduce here a theoretical model that allows for a systematic analysis of wrinkling in sheets far from their instability threshold. We focus on the simplest extension of Euler buckling that exhibits wrinkles of finite length - a sheet under axisymmetric tensile loads. This geometry, whose first study is attributed to Lam´e, allows us to construct\ud a phase diagram that demonstrates the dramatic variation of wrinkling patterns from near-threshold to far-from-threshold conditions. Theoretical arguments and comparison to experiments show that for thin sheets the far-from-threshold regime is expected to emerge under extremely small compressive loads, emphasizing the relevance of our analysis for nanomechanics applications
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