Two-electron temperature model of a laser-driven implosion

The plasma ejected by a pellet irradiated with moderately intense laser light (Icrλ2 ∼1015 W cm−2 μm2, Icr and λ being intensity and wavelength) is analyzed. Both hot electrons caused by resonant absorption, and cold or thermal electrons are considered; no appeal is made to heat‐flux saturation. The cold (hot) population controls the overdense (underdense) plasma flow. Ingoing hot electrons at the critical surface are found to thermalize before reaching the ablation surface. Results obtained are compared with a model that assume one electron temperature, and a saturated flux; agreement requires using a range of saturation factors: 0.1≲f≲0.3. The validity of the model is discussed

Symptom profiles and accuracy of clinical case definitions for COVID-19 in a community cohort: results from the Virus Watch study

Background: Understanding symptomatology and accuracy of clinical case definitions for community COVID-19 cases is important for Test, Trace and Isolate (TTI) and future targeting of early antiviral treatment. Methods: Community cohort participants prospectively recorded daily symptoms and swab results (mainly undertaken through the UK TTI system). We compared symptom frequency, severity, timing, and duration in test positive and negative illnesses. We compared the test performance of the current UK TTI case definition (cough, high temperature, or loss of or altered sense of smell or taste) with a wider definition adding muscle aches, chills, headache, or loss of appetite. Results: Among 9706 swabbed illnesses, including 973 SARS-CoV-2 positives, symptoms were more common, severe and longer lasting in swab positive than negative illnesses. Cough, headache, fatigue, and muscle aches were the most common symptoms in positive illnesses but also common in negative illnesses. Conversely, high temperature, loss or altered sense of smell or taste and loss of appetite were less frequent in positive illnesses, but comparatively even less frequent in negative illnesses. The current UK definition had 81% sensitivity and 47% specificity versus 93% and 27% respectively for the broader definition. 1.7-fold more illnesses met the broader case definition than the current definition. Conclusions: Symptoms alone cannot reliably distinguish COVID-19 from other respiratory illnesses. Adding additional symptoms to case definitions could identify more infections, but with a large increase in the number needing testing and the number of unwell individuals and contacts self-isolating whilst awaiting results

Strengthening organizational performance through accreditation research - a framework for twelve interrelated studies: the ACCREDIT project study protocol

Background: Service accreditation is a structured process of recognising and promoting performance and adherence to standards. Typically, accreditation agencies either receive standards from an authorized body or develop new and upgrade existing standards through research and expert views. They then apply standards, criteria and performance indicators, testing their effects, and monitoring compliance with them. The accreditation process has been widely adopted. The international investments in accreditation are considerable. However, reliable evidence of its efficiency or effectiveness in achieving organizational improvements is sparse and the value of accreditation in cost-benefit terms has yet to be demonstrated. Although some evidence suggests that accreditation promotes the improvement and standardization of care, there have been calls to strengthen its research base. In response, the ACCREDIT (Accreditation Collaborative for the Conduct of Research, Evaluation and Designated Investigations through Teamwork) project has been established to evaluate the effectiveness of Australian accreditation in achieving its goals. ACCREDIT is a partnership of key researchers, policymakers and agencies.FindingsWe present the framework for our studies in accreditation. Four specific aims of the ACCREDIT project, which will direct our findings, are to: (i) evaluate current accreditation processes; (ii) analyse the costs and benefits of accreditation; (iii) improve future accreditation via evidence; and (iv) develop and apply new standards of consumer involvement in accreditation. These will be addressed through 12 interrelated studies designed to examine specific issues identified as a high priority. Novel techniques, a mix of qualitative and quantitative methods, and randomized designs relevant for health-care research have been developed. These methods allow us to circumvent the fragmented and incommensurate findings that can be generated in small-scale, project-based studies. The overall approach for our research is a multi-level, multi-study design.DiscussionThe ACCREDIT project will examine the utility, reliability, relevance and cost effectiveness of differing forms of accreditation, focused on general practice, aged care and acute care settings in Australia. Empirically, there are potential research gains to be made by understanding accreditation and extending existing knowledge; theoretically, this design will facilitate a systems view of accreditation of benefit to the partnership, international research communities, and future accreditation designers

Genomic epidemiology of SARS-CoV-2 in a UK university identifies dynamics of transmission

AbstractUnderstanding SARS-CoV-2 transmission in higher education settings is important to limit spread between students, and into at-risk populations. In this study, we sequenced 482 SARS-CoV-2 isolates from the University of Cambridge from 5 October to 6 December 2020. We perform a detailed phylogenetic comparison with 972 isolates from the surrounding community, complemented with epidemiological and contact tracing data, to determine transmission dynamics. We observe limited viral introductions into the university; the majority of student cases were linked to a single genetic cluster, likely following social gatherings at a venue outside the university. We identify considerable onward transmission associated with student accommodation and courses; this was effectively contained using local infection control measures and following a national lockdown. Transmission clusters were largely segregated within the university or the community. Our study highlights key determinants of SARS-CoV-2 transmission and effective interventions in a higher education setting that will inform public health policy during pandemics.</jats:p

Global, regional, and national burden of disorders affecting the nervous system, 1990–2021: a systematic analysis for the Global Burden of Disease Study 2021

BackgroundDisorders affecting the nervous system are diverse and include neurodevelopmental disorders, late-life neurodegeneration, and newly emergent conditions, such as cognitive impairment following COVID-19. Previous publications from the Global Burden of Disease, Injuries, and Risk Factor Study estimated the burden of 15 neurological conditions in 2015 and 2016, but these analyses did not include neurodevelopmental disorders, as defined by the International Classification of Diseases (ICD)-11, or a subset of cases of congenital, neonatal, and infectious conditions that cause neurological damage. Here, we estimate nervous system health loss caused by 37 unique conditions and their associated risk factors globally, regionally, and nationally from 1990 to 2021.MethodsWe estimated mortality, prevalence, years lived with disability (YLDs), years of life lost (YLLs), and disability-adjusted life-years (DALYs), with corresponding 95% uncertainty intervals (UIs), by age and sex in 204 countries and territories, from 1990 to 2021. We included morbidity and deaths due to neurological conditions, for which health loss is directly due to damage to the CNS or peripheral nervous system. We also isolated neurological health loss from conditions for which nervous system morbidity is a consequence, but not the primary feature, including a subset of congenital conditions (ie, chromosomal anomalies and congenital birth defects), neonatal conditions (ie, jaundice, preterm birth, and sepsis), infectious diseases (ie, COVID-19, cystic echinococcosis, malaria, syphilis, and Zika virus disease), and diabetic neuropathy. By conducting a sequela-level analysis of the health outcomes for these conditions, only cases where nervous system damage occurred were included, and YLDs were recalculated to isolate the non-fatal burden directly attributable to nervous system health loss. A comorbidity correction was used to calculate total prevalence of all conditions that affect the nervous system combined.FindingsGlobally, the 37 conditions affecting the nervous system were collectively ranked as the leading group cause of DALYs in 2021 (443 million, 95% UI 378–521), affecting 3·40 billion (3·20–3·62) individuals (43·1%, 40·5–45·9 of the global population); global DALY counts attributed to these conditions increased by 18·2% (8·7–26·7) between 1990 and 2021. Age-standardised rates of deaths per 100 000 people attributed to these conditions decreased from 1990 to 2021 by 33·6% (27·6–38·8), and age-standardised rates of DALYs attributed to these conditions decreased by 27·0% (21·5–32·4). Age-standardised prevalence was almost stable, with a change of 1·5% (0·7–2·4). The ten conditions with the highest age-standardised DALYs in 2021 were stroke, neonatal encephalopathy, migraine, Alzheimer's disease and other dementias, diabetic neuropathy, meningitis, epilepsy, neurological complications due to preterm birth, autism spectrum disorder, and nervous system cancer.InterpretationAs the leading cause of overall disease burden in the world, with increasing global DALY counts, effective prevention, treatment, and rehabilitation strategies for disorders affecting the nervous system are needed

Global burden of 288 causes of death and life expectancy decomposition in 204 countries and territories and 811 subnational locations, 1990–2021: a systematic analysis for the Global Burden of Disease Study 2021

BACKGROUND Regular, detailed reporting on population health by underlying cause of death is fundamental for public health decision making. Cause-specific estimates of mortality and the subsequent effects on life expectancy worldwide are valuable metrics to gauge progress in reducing mortality rates. These estimates are particularly important following large-scale mortality spikes, such as the COVID-19 pandemic. When systematically analysed, mortality rates and life expectancy allow comparisons of the consequences of causes of death globally and over time, providing a nuanced understanding of the effect of these causes on global populations. METHODS The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2021 cause-of-death analysis estimated mortality and years of life lost (YLLs) from 288 causes of death by age-sex-location-year in 204 countries and territories and 811 subnational locations for each year from 1990 until 2021. The analysis used 56 604 data sources, including data from vital registration and verbal autopsy as well as surveys, censuses, surveillance systems, and cancer registries, among others. As with previous GBD rounds, cause-specific death rates for most causes were estimated using the Cause of Death Ensemble model-a modelling tool developed for GBD to assess the out-of-sample predictive validity of different statistical models and covariate permutations and combine those results to produce cause-specific mortality estimates-with alternative strategies adapted to model causes with insufficient data, substantial changes in reporting over the study period, or unusual epidemiology. YLLs were computed as the product of the number of deaths for each cause-age-sex-location-year and the standard life expectancy at each age. As part of the modelling process, uncertainty intervals (UIs) were generated using the 2·5th and 97·5th percentiles from a 1000-draw distribution for each metric. We decomposed life expectancy by cause of death, location, and year to show cause-specific effects on life expectancy from 1990 to 2021. We also used the coefficient of variation and the fraction of population affected by 90% of deaths to highlight concentrations of mortality. Findings are reported in counts and age-standardised rates. Methodological improvements for cause-of-death estimates in GBD 2021 include the expansion of under-5-years age group to include four new age groups, enhanced methods to account for stochastic variation of sparse data, and the inclusion of COVID-19 and other pandemic-related mortality-which includes excess mortality associated with the pandemic, excluding COVID-19, lower respiratory infections, measles, malaria, and pertussis. For this analysis, 199 new country-years of vital registration cause-of-death data, 5 country-years of surveillance data, 21 country-years of verbal autopsy data, and 94 country-years of other data types were added to those used in previous GBD rounds. FINDINGS The leading causes of age-standardised deaths globally were the same in 2019 as they were in 1990; in descending order, these were, ischaemic heart disease, stroke, chronic obstructive pulmonary disease, and lower respiratory infections. In 2021, however, COVID-19 replaced stroke as the second-leading age-standardised cause of death, with 94·0 deaths (95% UI 89·2-100·0) per 100 000 population. The COVID-19 pandemic shifted the rankings of the leading five causes, lowering stroke to the third-leading and chronic obstructive pulmonary disease to the fourth-leading position. In 2021, the highest age-standardised death rates from COVID-19 occurred in sub-Saharan Africa (271·0 deaths [250·1-290·7] per 100 000 population) and Latin America and the Caribbean (195·4 deaths [182·1-211·4] per 100 000 population). The lowest age-standardised death rates from COVID-19 were in the high-income super-region (48·1 deaths [47·4-48·8] per 100 000 population) and southeast Asia, east Asia, and Oceania (23·2 deaths [16·3-37·2] per 100 000 population). Globally, life expectancy steadily improved between 1990 and 2019 for 18 of the 22 investigated causes. Decomposition of global and regional life expectancy showed the positive effect that reductions in deaths from enteric infections, lower respiratory infections, stroke, and neonatal deaths, among others have contributed to improved survival over the study period. However, a net reduction of 1·6 years occurred in global life expectancy between 2019 and 2021, primarily due to increased death rates from COVID-19 and other pandemic-related mortality. Life expectancy was highly variable between super-regions over the study period, with southeast Asia, east Asia, and Oceania gaining 8·3 years (6·7-9·9) overall, while having the smallest reduction in life expectancy due to COVID-19 (0·4 years). The largest reduction in life expectancy due to COVID-19 occurred in Latin America and the Caribbean (3·6 years). Additionally, 53 of the 288 causes of death were highly concentrated in locations with less than 50% of the global population as of 2021, and these causes of death became progressively more concentrated since 1990, when only 44 causes showed this pattern. The concentration phenomenon is discussed heuristically with respect to enteric and lower respiratory infections, malaria, HIV/AIDS, neonatal disorders, tuberculosis, and measles. INTERPRETATION Long-standing gains in life expectancy and reductions in many of the leading causes of death have been disrupted by the COVID-19 pandemic, the adverse effects of which were spread unevenly among populations. Despite the pandemic, there has been continued progress in combatting several notable causes of death, leading to improved global life expectancy over the study period. Each of the seven GBD super-regions showed an overall improvement from 1990 and 2021, obscuring the negative effect in the years of the pandemic. Additionally, our findings regarding regional variation in causes of death driving increases in life expectancy hold clear policy utility. Analyses of shifting mortality trends reveal that several causes, once widespread globally, are now increasingly concentrated geographically. These changes in mortality concentration, alongside further investigation of changing risks, interventions, and relevant policy, present an important opportunity to deepen our understanding of mortality-reduction strategies. Examining patterns in mortality concentration might reveal areas where successful public health interventions have been implemented. Translating these successes to locations where certain causes of death remain entrenched can inform policies that work to improve life expectancy for people everywhere. FUNDING Bill & Melinda Gates Foundation

The standard of healthcare accreditation standards: a review of empirical research underpinning their development and impact

Abstract Background Healthcare accreditation standards are advocated as an important means of improving clinical practice and organisational performance. Standard development agencies have documented methodologies to promote open, transparent, inclusive development processes where standards are developed by members. They assert that their methodologies are effective and efficient at producing standards appropriate for the health industry. However, the evidence to support these claims requires scrutiny. The study’s purpose was to examine the empirical research that grounds the development methods and application of healthcare accreditation standards. Methods A multi-method strategy was employed over the period March 2010 to August 2011. Five academic health research databases (Medline, Psych INFO, Embase, Social work abstracts, and CINAHL) were interrogated, the websites of 36 agencies associated with the study topic were investigated, and a snowball search was undertaken. Search criteria included accreditation research studies, in English, addressing standards and their impact. Searching in stage 1 initially selected 9386 abstracts. In stage 2, this selection was refined against the inclusion criteria; empirical studies (n = 2111) were identified and refined to a selection of 140 papers with the exclusion of clinical or biomedical and commentary pieces. These were independently reviewed by two researchers and reduced to 13 articles that met the study criteria. Results The 13 articles were analysed according to four categories: overall findings; standards development; implementation issues; and impact of standards. Studies have only occurred in the acute care setting, predominately in 2003 (n = 5) and 2009 (n = 4), and in the United States (n = 8). A multidisciplinary focus (n = 9) and mixed method approach (n = 11) are common characteristics. Three interventional studies were identified, with the remaining 10 studies having research designs to investigate clinical or organisational impacts. No study directly examined standards development or other issues associated with their progression. Only one study noted implementation issues, identifying several enablers and barriers. Standards were reported to improve organisational efficiency and staff circumstances. However, the impact on clinical quality was mixed, with both improvements and a lack of measurable effects recorded. Conclusion Standards are ubiquitous within healthcare and are generally considered to be an important means by which to improve clinical practice and organisational performance. However, there is a lack of robust empirical evidence examining the development, writing, implementation and impacts of healthcare accreditation standards.</p

Profiling health-care accreditation organizations : an international survey

Objective. To describe global patterns among health-care accreditation organizations (AOs) and to identify determinants of sustainability and opportunities for improvement. Design. Web-based questionnaire survey. Participants. Organizations offering accreditation services nationally or internationally to health-care provider institutions or networks at primary, secondary or tertiary level in 2010. Main Outcome Measure(s). External relationships, scope and activity public information. Results. Forty-four AOs submitted data, compared with 33 in a survey 10 years earlier. Of the 30 AOs that reported survey activity in 2000 and 2010, 16 are still active and stable or growing. New and old programmes are increasingly linked to public funding and regulation. Conclusions. While the number of health-care AOs continues to grow, many fail to thrive. Successful organizations tend to complement mechanisms of regulation, health-care funding or governmental commitment to quality and health-care improvement that offer a supportive environment. Principal challenges include unstable business (e.g. limited market, low uptake) and unstable politics. Many organizations make only limited information available to patients and the public about standards, procedures or results.10 page(s