456 research outputs found

    Application of relativistic scattering theory of x rays to diffraction anomalous fine structure in Cu

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    We apply our recent first-principles formalism of magnetic scattering of circularly polarized x rays to a single Cu crystal. We demonstrate the ability of our formalism to interpret the crystalline environment related near-edge fine structure features in the resonant x-ray scattering spectra at the Cu K absorption edge. We find good agreement between the computed and measured diffraction anomalous fine structure features of the x-ray scattering spectra

    Composition, microstructure, and mechanical properties of Megalops atlanticus scales

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    In recent years, there has been an increased interest on understanding the mechanical behavior and microstructure of fish scales aiming at the development of bioinspired materials. This study presents a study of the composition, microstructure, and mechanical properties of the scales of Tarpon fish (Megalops atlanticus). Mechanical properties were evaluated in uniaxial tension as a function of positions along the length of the fish (head, midlength, and tail). Because of the possible anisotropy of the scales, additional tensile tests were performed on three different orientations (0°, 45°, and 90°). Examination of the fish scale microstructure and composition were performed by means of Scanning Electron Microscopy and RAMAN spectroscopy. The results showed that the scales are anisotropic with variation of the mechanical properties as a function of body position. Megalops atlantiticus scales are composed of fibrous collagen and hydroxyapatite crystals. The scales have a nonhomogenous distribution crosswise and lengthwise, providing multifunctional characteristics, which can be exploited on bioinspired materials

    Self-reported health problems and obesity predict sickness absence during a 12-month follow-up : a prospective cohort study in 21 608 employees from different industries

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    Objectives To study whether self-reported health problems predict sickness absence (SA) from work in employees from different industries. Methods The results of a health risk appraisal (HRA) were combined with archival data of SA of 21 608 employees (59% female, 56% clerical). Exposure variables were self-reported health problems, labelled as ' work disability (WD) risk factors' in the HRA, presence of problems with occupational well-being and obesity. Age, socioeconomic grading and the number of SA days 12 months before the survey were treated as confounders. The outcome measure was accumulated SA days during 12-month follow-up. Data were analysed separately for males and females. A Hurdle model with negative binomial response was used to analyse zero-inflated count data of SA. Results The HRA results predicted the number of accumulated SA days during the 12-month follow-up, regardless of occupational group and gender. The ratio of means of SA days varied between 2.7 and 4.0 among those with ' WD risk factors' and the reference category with no findings, depending on gender and occupational group. The lower limit of the 95% CI was at the lowest 2.0. In the Hurdle model, ' WD risk factors', SA days prior to the HRA and obesity were additive predictors for SA and/or the accumulated SA days in all occupational groups. Conclusion Self-reported health problems and obesity predict a higher total count of SA days in an additive fashion. These findings have implications for both management and the healthcare system in the prevention of WD. © Author(s) (or their employer(s)) 2019. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.Peer reviewe

    Immunohistochemical Expression of Somatostatin Receptor Subtypes in a Panel of Neuroendocrine Neoplasias

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    Neuroendocrine neoplasias (NENs) are known to express somatostatin receptors (SSTRs) 1-5, which are G-protein-coupled cell membrane receptors. Somatostatin receptor imaging and therapy utilizes the SSTR expression. Synthetic somatostatin analogs with radioligands are used to detect primary tumors, metastases, and recurrent disease. Receptor analogs are also used for treating NENs. Furthermore, commercially available SSTR antibodies can be used for the immunohistochemical (IHC) detection of SSTRs. We investigated different SSTR antibody clones applying diverse IHC protocol settings to identify reliable clones and feasible protocols for NENs. A tissue microarray including NENs from 12 different primary sites were stained. Only UMB clones were able to localize SSTR on the cell membranes of NENs. SSTR2 (UMB1) emerged as the most common subtype followed by SSTR5 (UMB4) and SSTR1 (UMB7). SSTR3 (UMB5) expression was mainly cytoplasmic. Yet, SSTR4 expression was weak and located primarily in the cytoplasm. Thus, appropriate IHC protocols, including proper positive and negative controls, represent requirements for high-quality NEN diagnostics and for planning personalized therapy.Peer reviewe

    Seasonal cycle and source analyses of aerosol optical properties in a semi-urban environment at Puijo station in Eastern Finland

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    We introduce a four-year (in 2006–2010) continuous data set of aerosol optical properties at Puijo in Kuopio, Finland. We study the annual and diurnal variation of the aerosol scattering and absorption coefficients, hemispheric backscattering fraction, scattering Ångström exponent, and single scattering albedo, whose median values over this period were 7.2 Mm<sup>−1</sup> (at 550 nm), 1.0 Mm<sup>−1</sup> (at 637 nm), 0.15, 1.93 (between 450 and 550 nm), and 0.85, respectively. The scattering coefficient peaked in the spring and autumn, being 2–4 times those in the summer and winter. An exception was the summer of 2010, when the scattering coefficient was elevated to ~300 Mm<sup>−1</sup> by plumes from forest fires in Russia. The absorption coefficient peaked in the winter when soot-containing particles derived from biomass burning were present. The higher relative absorption coefficients resulted in lower single scattering albedo in winter. The optical properties varied also with wind direction and time of the day, indicating the effect of the local pollutant sources and the age of the particles. Peak values in the single scattering albedo were observed when the wind blew from a paper mill and from the sector without local pollutant sources. These observations were linked, respectively, to the sulphate-rich aerosol from the paper mill and the oxygenated organics in the aged aerosol, which both are known to increase the scattering characteristics of aerosols. Decreases in the single scattering albedo in the morning and afternoon, distinct in the summertime, were linked to the increased traffic density at these hours. The scattering and absorption coefficients of residential and long-range transported aerosol (two separate cloud events) were found to be decreased by clouds. The effect was stronger for the scattering than absorption, indicating preferential activation of the more hygroscopic aerosol with higher scattering characteristics

    Relativistic theory of magnetic scattering of x rays: Application to ferromagnetic iron

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    We present a detailed description of a first-principles formalism for magnetic scattering of circularly polar- ized x rays from solids in the framework of the fully relativistic spin-polarized multiple-scattering theory. The scattering amplitudes are calculated using a standard time-dependent perturbation theory to second order in the electron-photon interaction vertex. Particular attention is paid to understanding the relative importance of the positive- and negative-energy solutions of the Dirac equation to the scattering amplitude. The advantage of the present theory as compared with other recent works on magnetic x-ray scattering is that, being fully relativistic, spin-orbit coupling and spin-polarization effects are treated on an equal footing. Second, the electron Green’s function expressed in terms of the path operators in the multiple-scattering theory allows us to include the contribution of the crystalline environment to the scattering amplitude. To illustrate the use of the method we have done calculations on the anomalous magnetic scattering at the K , L_II , and L_III absorption edges of ferromagnetic iron

    Histologically Verified Biliary Invasion was Associated with Impaired Liver Recurrence-Free Survival in Resected Colorectal Cancer Liver Metastases

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    Background and Aims: The impact of biliary invasion on recurrence and survival, after resection of colorectal cancer liver metastases, is not well known as publications are limited to small patient series. The aim was to investigate if biliary invasion in liver resected patients associated with liver relapses and recurrence-free survival. Secondary endpoints included association with other prognostic factors, disease-free survival and overall survival. Materials and Methods: All patients with histologically verified biliary invasion (n = 31, 9%) were identified among 344 patients with liver resection between January 2009 and March 2015. Controls (n = 78) were selected from the same time period and matched for, among others, size and number of colorectal cancer liver metastasis. Results: Median liver recurrence-free survival was significantly shorter in patients with biliary invasion than in controls (15.3 months versus not reached; p = 0.031) and more relapses were noted in the liver (61.3% versus 33.3%; p = 0.010), respectively. In univariate analyses for liver recurrence-free survival, biliary invasion was the only significant prognostic factor; p = 0.034. There were no statistical differences in disease-free and overall survival between the groups. Conclusion: Biliary invasion was associated with higher liver recurrence rates and shorter liver recurrence-free survival in patients with resected colorectal cancer liver metastasis.Peer reviewe

    Band offset determination of the GaAs/GaAsN interface using the DFT method

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    The GaAs/GaAsN interface band offset is calculated from first principles. The electrostatic potential at the core regions of the atoms is used to estimate the interface potential and align the band structures obtained from respective bulk calculations. First, it is shown that the present method performs well on the well-known conventional/conventional AlAs/GaAs (001) superlattice system. Then the method is applied to a more challenging nonconventional/conventional GaAsN/GaAs (001) system, and consequently type I band lineup and valence-band offset of about 35 meV is obtained for nitrogen concentration of about 3 %, in agreement with the recent experiments. We also investigate the effect of strain on the band lineup. For the GaAsN layer longitudinally strained to the GaAs lattice constant, the type II lineup with a nearly vanishing band offset is found, suggesting that the anisotropic strain along the interface is the principal cause for the often observed type I lineup
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