783 research outputs found

    Characterizing flows with an instrumented particle measuring Lagrangian accelerations

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    We present in this article a novel Lagrangian measurement technique: an instrumented particle which continuously transmits the force/acceleration acting on it as it is advected in a flow. We develop signal processing methods to extract information on the flow from the acceleration signal transmitted by the particle. Notably, we are able to characterize the force acting on the particle and to identify the presence of a permanent large-scale vortex structure. Our technique provides a fast, robust and efficient tool to characterize flows, and it is particularly suited to obtain Lagrangian statistics along long trajectories or in cases where optical measurement techniques are not or hardly applicable.Comment: submitted to New Journal of Physic

    Ariel - Volume 10 Number 3

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    Executive Editors Madalyn Schaefgen David Reich Business Manager David Reich News Editors Medical College Edward Zurad CAHS John Guardiani World Mark Zwanger Features Editors Meg Trexler Jim O\u27Brien Editorials Editor Jeffrey Banyas Photography and Sports Editor Stuart Singer Commons Editor Brenda Peterso

    Hot Interstellar Gas and Stellar Energy Feedback in the Antennae Galaxies

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    We have analyzed Chandra archival observations of the Antennae galaxies to study the distribution and physical properties of its hot interstellar gas. Eleven distinct diffuse X-ray emission regions are selected according to their underlying interstellar structures and star formation activity. The X-ray spectra of these regions are used to determine their thermal energy contents and cooling timescales. Young star clusters in these regions are also identified and their photometric measurements are compared to evolutionary stellar population synthesis models to assess their masses and ages. The cluster properties are then used to determine the stellar wind and supernova energies injected into the ISM. Comparisons between the thermal energy in the hot ISM and the expected stellar energy input show that young star clusters are sufficient to power the X-ray-emitting gas in some, but not all, active star formation regions. Super-star clusters, with masses >= 1x10^5 M_sol, heat the ISM, but the yield of hot interstellar gas is not directly proportional to the cluster mass. Finally, there exist diffuse X-ray emission regions which do not show active star formation or massive young star clusters. These regions may be powered by field stars or low-mass clusters formed within the last ~100 Myr.Comment: 36 pages, 6 figures, 8 tables, 2 appendices, to appear in the Astrophysical Journal, April 20 issu

    Prevalence and factors associated with sleep disturbance in adult patients with psoriasis

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    Background: Sleep, which is crucial for restoring of physiological functions and health, is reportedly impaired in psoriasis. The role of different potential sleep confounding factors, including detailed pruritus characteristics, and the complex interplay between psychological variables (anxiety and depression), pruritus and sleep disturbance in psoriasis remain insufficiently investigated. Objectives: To investigate sleep characteristics and to identify clinical, demographic and psychological factors associated with sleep disturbance in psoriasis. Methods: This cross-sectional study included 334 psoriasis patients (response rate 86%) and 126 control subjects (response rate 82%). Measures included sleep quality [Pittsburgh Sleep Quality Index (PSQI)], psoriasis severity, pruritus characteristics, including average pruritus intensity [visual analogue scale (VAS)], severity of comorbidities, anxiety and depression (Hospital Anxiety and Depression Scale - HADS) and quality of life (Dermatology Life Quality Index - DLQI, and Short Form 12 - SF12). Results: Fifty-nine per cent of patients and 34% of control subjects (P 5). Patients slept 1 h less than control subjects (median 6 vs. 7 h, P < 0.001). Patients without pruritus had less impaired sleep (global PSQI) than patients with strong (P < 0.001) and very strong pruritus (P < 0.001). Anxiety (HADS-A) and depression (HADS-D) levels were the strongest predictors of sleep impairment, followed by pruritus exacerbation at night, age, female sex, pruritus exacerbation in the morning, average pruritus intensity (VAS), diagnosed depression and gastroesophageal reflux disease, altogether explaining 32%-37% of the variance in global sleep quality. Both anxiety (HADS-A) and depression (HADS-D) were significant mediators explaining the association between pruritus intensity (VAS) and sleep impairment in 42% and 37% respectively. Conclusions: Sleep disturbance in patients with psoriasis is highly prevalent. Patients with psoriasis should be assessed for sleep impairment, pruritus, anxiety and depression. Reduction in pruritus should be considered as an important therapeutic goal, along with therapies aimed at reducing anxiety and depression

    Exposure of patients to di(2-ethylhexy)phthalate (DEHP) and its metabolite MEHP during extracorporeal membrane oxygenation (ECMO) therapy

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    The plasticizer di(2-ethylhexyl)phthalate (DEHP) is often used for PVC medical devices, that are also largely used for intensive care medical treatments, like extracorporeal membrane oxygenation (ECMO) therapy. Due to the toxicological potential of DEHP, the inner exposure of patients with this plasticizer is a strong matter of concern as many studies have shown a high leaching potential of DEHP into blood. In this study, the inner DEHP exposure of patients undergoing ECMO treatment was investigated. The determined DEHP blood levels of ECMO patients and the patients of the control group ranged from 31.5 to 1009 ÎŒg/L (median 156.0 ÎŒg/L) and from 19.4 to 75.3 ÎŒg/L (median 36.4 ÎŒg/L), respectively. MEHP blood levels were determined to range from < LOD to 475 ÎŒg/L (median 15.9 ÎŒg/L) in ECMO patients and from < LOD to 9.9 ÎŒg/L (median 3.7 ÎŒg/L) in the control group patients, respectively. Increased DEHP exposure was associated with the number of cannulas and membranes of the ECMO setting, whereas residual diuresis decreased the exposure. Due to the suspected toxicological potential of DEHP, its use in medical devices should be further investigated, in particular for ICU patients with long-term exposure to PVC, like in ECMO therapy

    A comparison of the hypoglycemic effect of insulin with systemic venous and portal venous administration

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    The hyperglycemic effect of insulin by prolonged intraportal and systemic infusion was measured in unanesthetized dogs with a modified portacaval transposition. There was no significant difference in response with the two routes of administration. The relation of these results to research directed to surgical therapy of diabetes is discussed. © 1963 W. B. Saunders Company

    A perspective on using experiment and theory to identify design principles in dye-sensitized solar cells

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    Dye-sensitized solar cells (DSCs) have been the subject of wide-ranging studies for many years because of their potential for large-scale manufacturing using roll-to-roll processing allied to their use of earth abundant raw materials. Two main challenges exist for DSC devices to achieve this goal; uplifting device efficiency from the 12 to 14% currently achieved for laboratory-scale ‘hero’ cells and replacement of the widely-used liquid electrolytes which can limit device lifetimes. To increase device efficiency requires optimized dye injection and regeneration, most likely from multiple dyes while replacement of liquid electrolytes requires solid charge transporters (most likely hole transport materials – HTMs). While theoretical and experimental work have both been widely applied to different aspects of DSC research, these approaches are most effective when working in tandem. In this context, this perspective paper considers the key parameters which influence electron transfer processes in DSC devices using one or more dye molecules and how modelling and experimental approaches can work together to optimize electron injection and dye regeneration. This paper provides a perspective that theory and experiment are best used in tandem to study DSC device
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