61 research outputs found

    Resonances in alpha-nuclei interaction

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    Tunnelling of α particles through the Coulomb barrier is considered. The main attention is given to the effect of sharp peaks arising in the case of coincidence of the α energy with that of a quasistaionary state within the barrier. The question of the α-nucleus potential is discussed in this light. The method is applied to the α decay of a compound nucleus of 135Pr. The appearance of the peaks in the spectrum of emitted particles is predicted. They can give rise to ‘anomalous’ properties of some neutron resonances. The peaks can also be observed in the incoming α-nucleus channel. Observation of the peaks would give unique information about the α-nucleus potential

    Examination of isospin effects in multi-dimensional Langevin fission dynamics

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    One-dimensional and three-dimensional dynamical fission calculations based on Langevin equations are performed for the compound nuclei Pb-194, Pb-200, Pb-206, Hg-182, and Hg-204 to investigate the influence of the compound nucleus isospin on the prescission particle multiplicities and oil the fission fragment mass-energy distribution It is found that the prescission neutron, proton, and alpha particle multiplicities have approximately the same sensitivity to the dissipation strength for a given nucleus This is at variance with Conclusions of recent papers The sensitivity of the calculated prescission particle Multiplicities to the dissipation strength becomes higher with decreasing isospin of fissioning compound nucleus, and the increase of prescission particle multiplicities could reach 200%, when the reduction coefficient of one-body viscosity k(s) increases from 0 1 to 1, for the most neutron deficient nuclei considered The variances of fission fragment mass and kinetic energy distributions are less sensitive to the change of dissipation strength than the prescission light particle multiplicities A comparison to experimental data concerning Pb-200 nucleus is also presented

    Outcomes from elective colorectal cancer surgery during the SARS-CoV-2 pandemic

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    This study aimed to describe the change in surgical practice and the impact of SARS-CoV-2 on mortality after surgical resection of colorectal cancer during the initial phases of the SARS-CoV-2 pandemic

    Mortality and pulmonary complications in patients undergoing surgery with perioperative SARS-CoV-2 infection: an international cohort study

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    Background: The impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on postoperative recovery needs to be understood to inform clinical decision making during and after the COVID-19 pandemic. This study reports 30-day mortality and pulmonary complication rates in patients with perioperative SARS-CoV-2 infection. Methods: This international, multicentre, cohort study at 235 hospitals in 24 countries included all patients undergoing surgery who had SARS-CoV-2 infection confirmed within 7 days before or 30 days after surgery. The primary outcome measure was 30-day postoperative mortality and was assessed in all enrolled patients. The main secondary outcome measure was pulmonary complications, defined as pneumonia, acute respiratory distress syndrome, or unexpected postoperative ventilation. Findings: This analysis includes 1128 patients who had surgery between Jan 1 and March 31, 2020, of whom 835 (74·0%) had emergency surgery and 280 (24·8%) had elective surgery. SARS-CoV-2 infection was confirmed preoperatively in 294 (26·1%) patients. 30-day mortality was 23·8% (268 of 1128). Pulmonary complications occurred in 577 (51·2%) of 1128 patients; 30-day mortality in these patients was 38·0% (219 of 577), accounting for 81·7% (219 of 268) of all deaths. In adjusted analyses, 30-day mortality was associated with male sex (odds ratio 1·75 [95% CI 1·28–2·40], p\textless0·0001), age 70 years or older versus younger than 70 years (2·30 [1·65–3·22], p\textless0·0001), American Society of Anesthesiologists grades 3–5 versus grades 1–2 (2·35 [1·57–3·53], p\textless0·0001), malignant versus benign or obstetric diagnosis (1·55 [1·01–2·39], p=0·046), emergency versus elective surgery (1·67 [1·06–2·63], p=0·026), and major versus minor surgery (1·52 [1·01–2·31], p=0·047). Interpretation: Postoperative pulmonary complications occur in half of patients with perioperative SARS-CoV-2 infection and are associated with high mortality. Thresholds for surgery during the COVID-19 pandemic should be higher than during normal practice, particularly in men aged 70 years and older. Consideration should be given for postponing non-urgent procedures and promoting non-operative treatment to delay or avoid the need for surgery. Funding: National Institute for Health Research (NIHR), Association of Coloproctology of Great Britain and Ireland, Bowel and Cancer Research, Bowel Disease Research Foundation, Association of Upper Gastrointestinal Surgeons, British Association of Surgical Oncology, British Gynaecological Cancer Society, European Society of Coloproctology, NIHR Academy, Sarcoma UK, Vascular Society for Great Britain and Ireland, and Yorkshire Cancer Research

    Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

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    Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

    Unexpected Large Deformations In Ni-60 Nuclei Produced In the Reaction 120 Mev Si-30+si-30

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    Alpha energy spectra and angular distribution have been measured for the reaction 120 MeV 30Si+30Si and compared to statistical model calculations. Emission from spherical nuclei cannot account for the shapes of the measured spectra. Reductions are required in both emission barrier and entrance channel spin. A simulation of alpha evaporation from deformed nuclei has been carried out using an equivalent one-step code. Average values of mass, charge, spin, and excitation energy of the emitter were evaluated by a multistep evaporative code. The very large deformation required to reproduce the experimental data agrees with previous results which have suggested a need for new physics in statistical models

    Reaction mechanism coexistence in the 123 MeV 19F+56Fe reaction

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    Mass and charge identified ejectiles, spanning from B-11 to Ne-22, have been detected in the 123 MeV F-19+ Fe-56 reaction. The coexistence of deep inelastic collision (DIC) and incomplete fusion (IF) mechanisms has been observed. The shape of the energy spectra and their behavior with angle allowed us to identify two components: The less dissipative one was dominating near the grazing angle. For both components experimental optimum Q values were derived. Two approaches based on the sum rule (SR) model of Wilczynski were used to calculate DIC and IF contributions to the complex fragment cross sections. Both prescriptions fit reasonably well experimental ejectile cross sections and Q optimum values. Results of the present investigation support the idea that the DIC can be treated on, the same footing as IF in the SR model once the first process is confined in an inner angular momentum window, starting from the maximum fusion angular momentum, with respect to quasielastic processes
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