1,035 research outputs found

    Microscopic Calculations of Weak Interaction Rates of Nuclei in Stellar Environment for A = 18 to 100

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    We report here the microscopic calculation of weak interaction rates in stellar matter for 709 nuclei with A = 18 to 100 using a generalized form of proton-neutron quasiparticle RPA model with separable Gamow-Teller forces. This is the first ever extensive microscopic calculation of weak rates calculated over a wide temperature-density grid which includes 10^7 \leq T(K) \leq 30 \times 10^9 and 10 \leq \rho Y_{e} (gcm^{-3}) \leq 10^{11}, and over a larger mass range. Particle emission processes from excited states, previously ignored, are taken into account, and are found to significantly affect some β\beta decay rates. The calculated capture and decay rates take into consideration the latest experimental energy levels and ftft value compilations. Our calculation of electron capture and β\beta-decay rates, in the fpfp-shell, show considerable differences with a recently reported shell model diagonalization approach calculation.Comment: 9 page

    rp-Process weak-interaction mediated rates of waiting-point nuclei

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    Electron capture and positron decay rates are calculated for neutron-deficient Kr and Sr waiting point nuclei in stellar matter. The calculation is performed within the framework of pn-QRPA model for rp-process conditions. Fine tuning of particle-particle, particle-hole interaction parameters and a proper choice of the deformation parameter resulted in an accurate reproduction of the measured half-lives. The same model parameters were used to calculate stellar rates. Inclusion of measured Gamow-Teller strength distributions finally led to a reliable calculation of weak rates that reproduced the measured half-lives well under limiting conditions. For the rp-process conditions, electron capture and positron decay rates on 72^{72}Kr and 76^{76}Sr are of comparable magnitude whereas electron capture rates on 78^{78}Sr and 74^{74}Kr are 1--2 orders of magnitude bigger than the corresponding positron decay rates. The pn-QRPA calculated electron capture rates on 74^{74}Kr are bigger than previously calculated. The present calculation strongly suggests that, under rp-process conditions, electron capture rates form an integral part of weak-interaction mediated rates and should not be neglected in nuclear reaction network calculations as done previously.Comment: 13 pages, 4 figures, 4 tables; Astrophysics and Space Science (2012

    Sleep disorders in children with chronic kidney disease

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    AbstractBackground and ObjectivesThis case-control study assessed the prevalence of sleep disorders among Egyptian children with chronic kidney disease (CKD), either maintained or not maintained on hemodialysis (HD), and compared them with healthy age and sex-matched children.Patients and methodsThe total study population included 95 children, 54 of whom were CKD patients, 22 maintained on HD and 32 not maintained on HD; 41 healthy children of matched age and sex composed the control group.Subjective impairment of sleep quality was assessed using the Arabic version of the Children's Sleep Habits Questionnaire (CSHQ). Daytime sleepiness and restless leg syndrome (RLS) were assessed using a pediatric modification of the Epworth sleepiness scale (ESS) and RLS Questionnaire, respectively.ResultsSleep disturbances were detected in 75.9% of the studied children with CKD: 81.8% in children with CKD undergoing dialysis, and 71.8% in children with CKD not on dialysis. Excessive daytime sleepiness (EDS) and RLS symptoms were reported in 22% and 20.4% of the studied children with CKD, respectively.ConclusionsSleep disturbances are very common among children with CKD. Sleep disturbances in patients with CKD include restless legs syndrome (RLS), excessive daytime sleepiness (EDS), sleep-disordered breathing (SDB), behavioral insomnias, and parasomnias

    ASSESSMENT OF TEMPORAL FLOW VARIABILITY OF THE KABUL RIVER

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    Water resources estimation under changing flow regimes is required for planning and smooth distribution of water to provinces. Since the hydrological parameters are changing significantly due to climate change, the changes in the pattern of flow regimes are definite. The objective of present study was to assess the spatial and temporal hydro variability of Indus basin. The data of Kabul river at Nowshera before its confluence with Indus river were collected from Surface water Hydrology Project (SWHP), WAPDA. The seasons were divided as three and six month keeping in view the hydrological cycle. Trends and variation were investigated by applying the Mann-Kendall test and Sen’s method. The presence of trends tested at different significant level, 99.9%, 95% and 90%. The overall analysis indicates that there is more flow variation on seasonal basis as compared to the annual basis. The Kabul river showed decreasing trend in the maximum mean annual discharge, whereas the minimum mean annual discharge showed increasing trend. It was concluded that Kabul river showed decreasing trend in annual mean and maximum discharge, whereas annual minimum discharge showed increasing trend. It was also noticed that Kabul river mean minimum discharge time series decreased during 1961-1985, whereas it increased during 1986-2010. It was also found that annual mean and maximum discharge decreasing rate was greater during 1986-2010. It was further concluded that each decade experienced one or two years of both dry and wet periods and that 2000-2004 was the driest period in the history of Kabul River

    Risk-stratified breast cancer screening incorporating a polygenic risk score: a survey of UK General Practitioners’ knowledge and attitudes

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    A polygenic risk score (PRS) quantifies the aggregated effects of common genetic variants in an individual. A ‘personalised breast cancer risk assessment’ combines PRS with other genetic and nongenetic risk factors to offer risk-stratified screening and interventions. Large-scale studies are evaluating the clinical utility and feasibility of implementing risk-stratified screening; however, General Practitioners’ (GPs) views remain largely unknown. This study aimed to explore GPs’: (i) knowledge of risk-stratified screening; (ii) attitudes towards risk-stratified screening; and (iii) preferences for continuing professional development. A cross-sectional online survey of UK GPs was conducted between July–August 2022. The survey was distributed by the Royal College of General Practitioners and via other mailing lists and social media. In total, 109 GPs completed the survey; 49% were not familiar with the concept of PRS. Regarding risk-stratified screening pathways, 75% agreed with earlier and more frequent screening for women at high risk, 43% neither agreed nor disagreed with later and less screening for women at lower-than-average risk, and 55% disagreed with completely removing screening for women at much lower risk. In total, 81% felt positive about the potential impact of risk-stratified screening towards patients and 62% felt positive about the potential impact on their practice. GPs selected training of healthcare professionals as the priority for future risk-stratified screening implementation, preferring online formats for learning. The results suggest limited knowledge of PRS and risk-stratified screening amongst GPs. Training—preferably using online learning formats—was identified as the top priority for future implementation. GPs felt positive about the potential impact of risk-stratified screening; however, there was hesitance and disagreement towards a low-risk screening pathway

    Understanding Collaboration Requirements for Modular Construction and their Cascading Failure Impact on Project Performance

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    Effective Implementation of Modularization Demands Close Collaboration among the Various Project Stakeholders Due to the Distinct and Complex Needs of Such Construction Method. in Fact, Lack of Adequate Collaboration is One of the Main Factors Impacting Modular Construction Performance. Despite that, No Previous Study Has Yet Addressed Collaboration Requirements in Modular Construction and their Cascading Failure Impact on Project Performance. This Paper Fills Such a knowledge Gap. to This End, the Authors Followed a Multistep Research Methodology. First, Systematic Literature Analysis Was Performed to Identify the Factors Impacting Collaboration and the Impacted Modular Risks as Well as their Cause-Effect Relationships. Second, Two Surveys Were Distributed to Collect (1) Importance Weights and Failure Probabilities for the Collaboration Factors; and (2) Failure Probabilities and Performance Impacts for the Modular Risks. Third, Network Analysis Was Conducted using In- and Out-Degree Centralities to Determine the Most Influential and Sensitive Aspects in Terms of Collaboration. Fourth, Independent Cascade Modeling Was Performed to Capture the Cascading Failure Effect of Various Collaboration Aspects on Project Performance. Ultimately, a Total of 25 Factors Were Found to Impact Collaboration Categorized under Four Themes, Including (1) Project Organization and Control, (2) Stakeholders\u27 Relationships and Characteristics, (3) Information Sharing, Documentation, and Technologies, and (4) Design and Construction Planning. Furthermore, 10 Modular Operation Risks Were Found to Be Impacted by Collaboration in Construction Projects. Although the Most Influential Factors Were Related to Information Sharing, Documentation, and Technologies, the Most Sensitive Factors Fell within the Design and Construction Planning. Most Importantly, Results Show that Inadequate Collaboration during Design and Construction Planning Can Lead to 70.6% Direct Growth in Schedule and Cost of Modularized Projects. This Paper Contributes to the Body of Knowledge by Offering an Unprecedented Framework that Investigates Collaboration Requirements in Modular Construction and their Interdependencies
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