601 research outputs found

    Double ionization of helium by electron-impact: complete pictures of the four-body breakup dynamics

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    The dynamics of He double ionization by 2 keV electron impact is studied experimentally for a momentum transfer of 0.6 a.u. at excess energies of 10 and 40 eV. Complete sets of fivefold differential cross sections are presented for all electron emission angles in coplanar geometry. Contributions beyond the first Born approximation are identified comparing experimental data with first order convergent close-coupling calculations which are in considerably better agreement with the present experiment than with the earlier measurement of Kheifets et al. [J. Phys. B 32, 5047 (1999)]

    Conflicts of interest in dermatology

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    Conflicts of interest exist in dermatology when professional judgement concerning a primary interest, such as research validity, may be influenced by a secondary interest, such as financial gain from a for-profit organization. Conflict of interest is a condition and not a behaviour, although there is clear evidence that gifts influence behaviour. Little has been written about conflicts of interest in dermatology. This series of papers raises awareness of the subject by exploring it in greater depth from the perspective of a dermatology researcher, an industry researcher, a dermatology journal editor, a health services researcher and a patient representative. Collectively, they illustrate the many ways in which conflicts can pervade the world of dermatology publications and patient support group activities

    Appearance and disappearance of the second Born effects in the (e,3e) reaction in He

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    We demonstrate, both experimentally and theoretically, clear manifestation of the second Born effects in the angular distributions of two ejected electrons produced by a 500 eV electron impact on the He atom in the so-called (e,3e) reaction. The second Born contribution, due to subsequent interaction of the projectile with the target, is most prominent for glancing collisions with small momentum transfer. However, these effects are absent for hard knock-out collisions with large momentum transfer

    Cyclosporin A and steroid therapy in sixty-six cadaver kidney recipients

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    From nine to 18 months ago, 66 patients were given 67 randomly matched cadaveric kidneys with cyclosporin A and steroid therapy. Nine of the recipients were undergoing retransplantation. The over-all kidney survival rate to date has been 77.6 per cent, and 78.8 per cent of the recipients are dialysis-free. The patient mortality in this learning phase was 13.3 per cent. Nephrotoxicity, hepatotoxicity and other side-effects of cyclosporin A could usually be dealt with by dosage adjustments, making feasible the chronic use of this agent. One B-cell immunoblastic sarcoma was encountered which was monoclonal. It was not responsible for death. Another patient had a perforation of the intestine from a lymphoproliferative reaction in which the B cells were polyclonal. After jejunal resection a year ago, there were no further complications. This lesion was not classified as a lymphoma. Both lymphoproliferative lesions were associated with a rise in antibody to viral capsid antigen of Epstein-Barr virus. Results of this study have verified the effectiveness and relative safety of cyclosporin A with steroids for immunosuppression in human recipients of cadaveric kidneys

    Assessing changes in airflow and energy loss in a progressive tracheal compression before and after surgical correction

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    The energy needed to drive airflow through the trachea normally constitutes a minor component of the work of breathing. However, with progressive tracheal compression, patient subjective symptoms can include severe breathing difficulties. Many patients suffer multiple respiratory co-morbidities and so it is important to assess compression effects when evaluating the need for surgery. This work describes the use of computational prediction to determine airflow resistance in compressed tracheal geometries reconstructed from a series of CT scans. Using energy flux analysis, the regions that contribute the most to airway resistance during inhalation are identified. The principal such region is where flow emerging from the zone of maximum constriction undergoes breakup and turbulent mixing. Secondary regions are also found below the tongue base and around the glottis, with overall airway resistance scaling nearly quadratically with flow rate. Since the anatomical extent of the imaged airway varied between scans - as commonly occurs with clinical data and when assessing reported differences between research studies - the effect of sub-glottic inflow truncation is considered. Analysis shows truncation alters the location of jet breakup and weakly influences the pattern of pressure recovery. Tests also show that placing a simple artificial glottis in the inflow to a truncated model can replicate patterns of energy loss in more extensive models, suggesting a means to assess sensitivity to domain truncation in tracheal airflow simulations

    Are reviewers suggested by authors as good as those chosen by editors? Results of a rater-blinded, retrospective study

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    BACKGROUND: BioMed Central (BMC) requires authors to suggest four reviewers when making a submission. Editors searching for reviewers use these suggestions as a source. The review process of the medical journals in the BMC series is open – authors and reviewers know each other's identity – although reviewers can make confidential comments to the editor. Reviews are published alongside accepted articles so readers may see the reviewers' names and recommendations. Our objective was to compare the performance of author-nominated reviewers (ANR) with that of editor-chosen reviewers (ECR) in terms of review quality and recommendations about submissions in an online-only medical journal. METHODS: Pairs of reviews from 100 consecutive submissions to medical journals in the BMC series (with one author-nominated and one editor-chosen reviewer and a final decision) were assessed by two raters, blinded to reviewer type, using a validated review quality instrument (RQI) which rates 7 items on 5-point Likert scales. The raters discussed their ratings after the first 20 pairs (keeping reviewer type masked) and resolved major discrepancies in scoring and interpretation to improve inter-rater reliability. Reviewers' recommendations were also compared. RESULTS: Reviewer source had no impact on review quality (mean RQI score (± SD) 2.24 ± 0.55 for ANR, 2.34 ± 0.54 for ECR) or tone (mean scores on additional question 2.72 ANR vs 2.82 ECR) (maximum score = 5 in both cases). However author-nominated reviewers were significantly more likely to recommend acceptance (47 vs 35) and less likely to recommend rejection (10 vs 23) than editor-chosen reviewers after initial review (p < 0.001). However, by the final review stage (i.e. after authors had responded to reviewer comments) ANR and ECR recommendations were similar (65 vs 66 accept, 10 vs 14 reject, p = 0.47). The number of reviewers unable to decide about acceptance was similar in both groups at both review stages. CONCLUSION: Author-nominated reviewers produced reviews of similar quality to editor-chosen reviewers but were more likely to recommend acceptance during the initial stages of peer review

    Is there plagiarism in the most influential publications in the field of andrology?

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    Plagiarism is a common form of academic misconduct that extensively jeopardises the quality of scientific publication. The purpose of this study is to determine the extent of plagiarism in the most influential andrology articles. A total of 77 highly cited andrology articles were analysed for their similarity index using iThenticate and Turnitin. The articles were categorised based on the year (before and on/after 2000) and type of publication (review and research articles), and the similarity indices were compared. Furthermore, the analysed articles were categorised based on the level of similarity using an arbitrary similarity index range (low: ≤10, moderate: 11–20, high: 21–50 and very high: >50) and average incidence rate (%) was determined. Our analysis revealed a higher percentage of the similarity indices for reviews than research articles. We noticed a higher similarity index for articles published on/after 2000 than those published before. The majority of the influential articles in the field of andrology showed a low similarity index, while some articles exhibited moderate to high levels of similarity. These findings support the need for the development of similarity index guidelines as a major pre‐requisite for establishing a more transparent and efficient system to address plagiarism in scientific publications

    Herd-level animal management factors associated with the occurrence of bovine neonatal pancytopenia in calves in a multicountry study

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    Since 2007, mortality associated with a previously unreported haemorrhagic disease has been observed in young calves in several European countries. The syndrome, which has been named ‘bovine neonatal pancytopenia’ (BNP), is characterised by thrombocytopenia, leukocytopenia and a panmyelophthisis. A herd-level case-control study was conducted in four BNP affected countries (Belgium, France, Germany and the Netherlands) to identify herd management risk factors for BNP occurrence. Data were collected using structured face-to-face and telephone interviews of farm managers and their local veterinarians. In total, 363 case farms and 887 control farms were included in a matched multivariable conditional logistic regression analysis. Case-control status was strongly associated with the odds of herd level use of the vaccine PregSure® BVD (PregSure, Pfizer Animal Health) (matched adjusted odds ratio (OR) 107.2; 95% CI: 41.0–280.1). This was also the case for the practices of feeding calves colostrum from the calf’s own dam (OR 2.0; 95% CI: 1.1–3.4) or feeding pooled colostrum (OR 4.1; 95% CI: 1.9–8.8). Given that the study had relatively high statistical power and represented a variety of cattle production and husbandry systems, it can be concluded with some confidence that no other herd level management factors are competent causes for a sufficient cause of BNP occurrence on herd level. It is suggested that genetic characteristics of the dams and BNP calves should be the focus of further investigations aimed at identifying the currently missing component causes that together with PregSure vaccination and colostrum feeding represent a sufficient cause for occurrence of BNP in calves

    Influence of orbital symmetry on diffraction imaging with rescattering electron wave packets

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    Citation: Pullen, M. G., Wolter, B., Le, A. T., Baudisch, M., Sclafani, M., Pires, H., . . . Biegert, J. (2016). Influence of orbital symmetry on diffraction imaging with rescattering electron wave packets. Nature Communications, 7, 6. doi:10.1038/ncomms11922The ability to directly follow and time-resolve the rearrangement of the nuclei within molecules is a frontier of science that requires atomic spatial and few-femtosecond temporal resolutions. While laser-induced electron diffraction can meet these requirements, it was recently concluded that molecules with particular orbital symmetries (such as pi(g)) cannot be imaged using purely backscattering electron wave packets without molecular alignment. Here, we demonstrate, in direct contradiction to these findings, that the orientation and shape of molecular orbitals presents no impediment for retrieving molecular structure with adequate sampling of the momentum transfer space. We overcome previous issues by showcasing retrieval of the structure of randomly oriented O-2 and C2H2 molecules, with pi(g) and pi(u) symmetries, respectively, and where their ionization probabilities do not maximize along their molecular axes. While this removes a serious bottleneck for laser-induced diffraction imaging, we find unexpectedly strong backscattering contributions from low-Z atoms
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