1,057 research outputs found

    An Experiment to Evaluate Skylab Earth Resources Sensors for Detection of the Gulf Stream

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    The author has identified the following significant results. An experiment to evaluate the Skylab earth resources package for observing ocean currents was performed in the Straits of Florida in January 1974. Data from the S190 photographic facility, S191 spectroradiometer and S192 multispectral scanner, were compared with surface observations. The anticyclonic edge of the Gulf Stream could be identified in the Skylab S190A and B photographs, but the cyclonic edge was obscured by clouds. The aircraft photographs were judged not useful for spectral analysis because vignetting caused the blue/green ratios to be dependent on the position in the photograph. The spectral measurement technique could not identify the anticyclonic front, but mass of Florida Bay water which was in the process of flowing into the Straits could be identified and classified. Monte Carlo simulations of the visible spectrum showed that the aerosol concentration could be estimated and a correction technique was devised

    Development of the mathematical model of catalytic cracking: identification of hydrocarbon of the vacuum distillate usin chromatomass- spectrometry

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    Information about composition of catalytic cracking raw materials and products is required fordevelopment of mathematical model of catalytic cracking. The results of laboratory investigation ondetermination of the composition of catalytic cracking vacuum distillate were performed in this work. Groupcomposition of the catalytic cracking raw materials was defined using liquid-adsorption chromatographicseparation on silica gel. Paraffin-naphthenic and aromatic fraction was indefined by chromato-massspectrometry

    Applying the extended molecule approach to correlated electron transport: important insight from model calculations

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    Theoretical approaches of electronic transport in correlated molecules usually consider an extended molecule, which includes, in addition to the molecule itself, parts of electrodes. In the case where electron correlations remain confined within the molecule, and the extended molecule is sufficiently large, the current can be expressed by means of Laudauer-type formulae. Electron correlations are embodied into the retarded Green function of a sufficiently large but isolated extended molecule, which represents the key quantity that can be accurately determined by means of ab initio quantum chemical calculations. To exemplify these ideas, we present and analyze numerical results obtained within full CI calculations for an extended molecule described by the interacting resonant level model. Based on them, we argue that for organic electrodes the transport properties can be reliably computed, because the extended molecule can be chosen sufficiently small to be tackled within accurate ab initio methods. For metallic electrodes, larger extended molecules have to be considered in general, but a (semi-)quantitative description of the transport should still be possible particularly in the typical cases where electron transport proceeds by off-resonant tunneling. Our numerical results also demonstrate that, contrary to the usual claim, the ratio between the characteristic Coulomb strength and the level width due to molecule-electrode coupling is not the only quantity needed to assess whether electron correlation effects are strong or weak

    A polarized version of the CCFM equation for gluons

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    A derivation for a polarized CCFM evolution equation which is suitable to describe the scaling behavior of the the unintegrated polarized gluon density is given. We discuss the properties of this polarized CCFM equation and compare it to the standard CCFM equation in the unpolarized case.Comment: 15 pages, 6 figures, RevTeX, some minor typos corrected, version to appear in Phys. Rev.

    Effects of COVID-19 Lockdown on Melanoma Diagnosis in Switzerland: Increased Tumor Thickness in Elderly Females and Shift towards Stage IV Melanoma during Lockdown.

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    At the early stages of the COVID-19 outbreak in 2020, Switzerland was among the countries with the highest number of SARS-CoV2-infections per capita in the world. Lockdowns had a remarkable impact on primary care access and resulted in postponed cancer screenings. The aim of this study was to investigate the effects of the COVID-19 lockdown on the diagnosis of melanomas and stage of melanomas at diagnosis. In this retrospective, exploratory cohort study, 1240 patients with a new diagnosis of melanoma were analyzed at five tertiary care hospitals in German-speaking Switzerland over a period of two years and three months. We compared the pre-lockdown (01/FEB/19-15/MAR/20, n = 655) with the lockdown (16/MAR/20-22/JUN/20, n = 148) and post-lockdown period (23/JUN/20-30/APR/21, n = 437) by evaluating patients' demographics and prognostic features using Breslow thickness, ulceration, subtype, and stages. We observed a short-term, two-week rise in melanoma diagnoses after the major lift of social lockdown restrictions. The difference of mean Breslow thicknesses was significantly greater in older females during the lockdown compared to the pre-lockdown (1.9 ± 1.3 mm, p = 0.03) and post-lockdown period (1.9 ± 1.3 mm, p = 0.048). Thickness increase was driven by nodular melanomas (2.9 ± 1.3 mm, p = 0.0021; resp. 2.6 ± 1.3 mm, p = 0.008). A proportional rise of advanced melanomas was observed during lockdown (p = 0.047). The findings provide clinically relevant insights into lockdown-related gender- and age-dependent effects on melanoma diagnosis. Our data highlight a stable course in new melanomas with a lower-than-expected increase in the post-lockdown period. The lockdown period led to a greater thickness in elderly women driven by nodular melanomas and a proportional shift towards stage IV melanoma. We intend to raise awareness for individual cancer care in future pandemic management strategies
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