125 research outputs found

    Hybrid Illinois Device for Research and Applications material analysis test-stand development for characterization of fusion plasma-material interactions

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    The Hybrid Illinois Device for Research and Applications (HIDRA) at the University of Illinois at Urbana-Champaign (UIUC) is the only tokamak-stellarator hybrid that is wholly dedicated to the study of material science, mainly research pertaining to fusion plasma facing components (PFCs). HIDRA’s long-pulse steady-state stellarator plasmas provide a unique plasma environment to test materials under the harsh conditions they will experience in a fusion device. To realize HIDRA’s potential to advance PFC research, the HIDRA-Material Analysis Test-stand (HIDRA-MAT) was designed and fabricated. HIDRA-MAT is an extension of HIDRA with the purpose of exposing materials to HIDRA stellarator plasmas and then performing in-vacuo surface characterization. HIDRA’s long-pulse plasmas emulate some environmental conditions samples will experience in larger fusion devices, which will help in PFC development by studying the plasma-material interactions. Sample preparation utilizes a high-linear shift mechanism with an attached UHV heater that is rotatable for sample positioning and diagnostic use. A liquid metal droplet injector (LMDI) allows for controlled in-vacuo liquid metal droplet creation and application to samples. HIDRA-MAT is equipped with a multitude of diagnostics capable of laser-induced breakdown spectroscopy (LIBS), laser-induced desorption spectroscopy (LIDS), thermal desorption spectroscopy (TDS), and He/D2 differentiation. Preliminary experimental data demonstrating the functionality of sample motion and rotation, the LMDI, and surface characterization diagnostics (LIBS, LIDS, and TDS), and He/D2 differentiation is reported. A ±5% error in He/D2 mixture concentration measurements has been demonstrated and the technique will be used to determine He and D2 retention in samples after plasma exposure. The LIBS system’s development and results are discussed describing how signal quality has been improved. Lithium peaks have been resolved in collected spectra and the implementation of dual-pulsed LIBS is expected to increase signal strength and allow for the identification of hydrogen and deuterium peaks. The LIBS system’s depth profiling capability has also been demonstrated. HIDRA and HIDRA-MAT together present a unique opportunity in the field of fusion PFC research and trailblazes the path for the accumulation of scientific knowledge on liquid metal-PFC-plasma interactions as liquid metals begin to showcase advantageous properties in fusion environments

    Aitchison's Compositional Data Analysis 40 Years On: A Reappraisal

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    The development of John Aitchison's approach to compositional data analysis is followed since his paper read to the Royal Statistical Society in 1982. Aitchison's logratio approach, which was proposed to solve the problematic aspects of working with data with a fixed sum constraint, is summarized and reappraised. It is maintained that the principles on which this approach was originally built, the main one being subcompositional coherence, are not required to be satisfied exactly -- quasi-coherence is sufficient, that is near enough to being coherent for all practical purposes. This opens up the field to using simpler data transformations, such as power transformations, that permit zero values in the data. The additional principle of exact isometry, which was subsequently introduced and not in Aitchison's original conception, imposed the use of isometric logratio transformations, but these are complicated and problematic to interpret, involving ratios of geometric means. If this principle is regarded as important in certain analytical contexts, for example unsupervised learning, it can be relaxed by showing that regular pairwise logratios, as well as the alternative quasi-coherent transformations, can also be quasi-isometric, meaning they are close enough to exact isometry for all practical purposes. It is concluded that the isometric and related logratio transformations such as pivot logratios are not a prerequisite for good practice, although many authors insist on their obligatory use. This conclusion is fully supported here by case studies in geochemistry and in genomics, where the good performance is demonstrated of pairwise logratios, as originally proposed by Aitchison, or Box-Cox power transforms of the original compositions where no zero replacements are necessary.Comment: 26 pages, 18 figures, plus Supplementary Material. This is a complete revision of the first version of this paper, placing the geochemical example upfront and adding a large section on CoDA of wide matrice

    Business and the Risk of Crime in China

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    The book analyses the results of a large scale victimisation survey that was conducted in 2005-06 with businesses in Hong Kong, Shanghai, Shenzhen and Xi’an. It also provides comprehensive background materials on crime and the criminal justice system in China. The survey, which measured common and non-conventional crime such as fraud, IP theft and corruption, is important because few crime victim surveys have been conducted with Chinese populations and it provides an understanding of some dimensions of crime in non-western societies. In addition, China is one of the fastest-growing economies in the world and it attracts a great amount of foreign investment; however, corruption and economic crimes are perceived by some investors as significant obstacles to good business practices. Key policy implications of the survey are discussed

    Resilience in American Indian and Alaska Native Public Health: An Underexplored Framework

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    Objective: To conduct a systematic literature review to assess the conceptualization, application, and measurement of resilience in American Indian and Alaska Native (AIAN) health promotion. Data Sources: We searched 9 literature databases to document how resilience is discussed, fostered, and evaluated in studies of AIAN health promotion in the United States. Study Inclusion and Exclusion Criteria: The article had to (1) be in English; (2) peer reviewed, published from January 1, 1980, to July 31, 2015; (3) identify the target population as predominantly AIANs in the United States; (4) describe a nonclinical intervention or original research that identified resilience as an outcome or resource; and (5) discuss resilience as related to cultural, social, and/or collective strengths. Data Extraction: Sixty full texts were retrieved and assessed for inclusion by 3 reviewers. Data were extracted by 2 reviewers and verified for relevance to inclusion criteria by the third reviewer. Data Synthesis: Attributes of resilience that appeared repeatedly in the literature were identified. Findings were categorized across the lifespan (age group of participants), divided by attributes, and further defined by specific domains within each attribute. Results: Nine articles (8 studies) met the criteria. Currently, resilience research in AIAN populations is limited to the identification of attributes and pilot interventions focused on individual resilience. Resilience models are not used to guide health promotion programming; collective resilience is not explored. Conclusion: Attributes of AIAN resilience should be considered in the development of health interventions. Attention to collective resilience is recommended to leverage existing assets in AIAN communities

    Recombinant antigens based on toxins A and B of Clostridium difficile that evoke a potent toxin-neutralising immune response

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    AbstractInfection with the bacterium Clostridium difficile causes symptoms ranging from mild to severe diarrhoea with life-threatening complications and remains a significant burden to healthcare systems throughout the developed world. Two potent cytotoxins, TcdA and TcdB are the prime mediators of the syndrome and rapid neutralisation of these would afford significant benefits in disease management. In the present study, a broad range of non-toxic, recombinant fragments derived from TcdA and TcdB were designed for soluble expression in E. coli and assessed for their capacity to generate a potent toxin-neutralising immune response as assessed by cell-based assays. Significant differences between the efficacies of isolated TcdA and TcdB regions with respect to inducing a neutralising immune response were observed. While the C-terminal repeat regions played the principal role in generating neutralising antibodies to TcdA, in the case of TcdB, the central region domains dominated the neutralising immune response. For both TcdA and TcdB, fragments which comprised domains from both the central and C-terminal repeat region of the toxins were found to induce the most potent neutralising immune responses. Generated antibodies neutralised toxins produced by a range of C. difficile isolates including ribotype 027 and 078 strains. Passive immunisation of hamsters with a combination of antibodies to TcdA and TcdB fragments afforded complete protection from severe CDI induced by a challenge of bacterial spores. The results of the study are discussed with respect to the development of a cost effective immunotherapeutic approach for the management of C. difficile infection

    Containment of socially optimal policies in multiple-facility Markovian queueing systems

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    We consider a Markovian queueing system with N heterogeneous service facilities, each of which has multiple servers available, linear holding costs, a fixed value of service and a first-come-first-serve queue discipline. Customers arriving in the system can be either rejected or sent to one of the N facilities. Two different types of control policies are considered, which we refer to as ‘selfishly optimal’ and ‘socially optimal’. We prove the equivalence of two different Markov Decision Process formulations, and then show that classical M/M/1 queue results from the early literature on behavioural queueing theory can be generalized to multiple dimensions in an elegant way. In particular, the state space of the continuous-time Markov process induced by a socially optimal policy is contained within that of the selfishly optimal policy. We also show that this result holds when customers are divided into an arbitrary number of heterogeneous classes, provided that the service rates remain non-discriminatory

    Associations between childhood maltreatment and psychiatric disorders: analysis from electronic health records in Hong Kong

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    There has been a lack of high-quality evidence concerning the association between childhood maltreatment and psychiatric diagnoses particularly for Axis II disorders. This study aimed to examine the association between childhood maltreatment exposure and Axis I and Axis II psychiatry disorders using electronic health records. In this study, the exposed group (n = 7473) comprised patients aged 0 to 19 years with a first-time record of maltreatment episode between January 1, 2001 and December 31, 2010, whereas the unexposed group (n = 26,834) comprised individuals of the same gender and age who were admitted into the same hospital in the same calendar year and month but had no records of maltreatment in the Hong Kong Clinical Data Analysis and Reporting System (CDARS). Data on their psychiatric diagnoses recorded from the date of admission to January 31, 2019 were extracted. A Cox proportional hazard regression model was fitted to estimate the hazard ratio (HR, plus 95% CIs) between childhood maltreatment exposure and psychiatric diagnoses, adjusting for age at index visit, sex, and government welfare recipient status. Results showed that childhood maltreatment exposure was significantly associated with subsequent diagnosis of conduct disorder/ oppositional defiant disorder (adjusted HR, 10.99 [95% CI 6.36, 19.01]), attention deficit hyperactivity disorder (ADHD) (7.28 [5.49, 9.65]), and personality disorders (5.36 [3.78, 7.59]). The risk of psychiatric disorders following childhood maltreatment did not vary by history of childhood sexual abuse, age at maltreatment exposure, and gender. Individuals with a history of childhood maltreatment are vulnerable to psychiatric disorders. Findings support the provision of integrated care within the primary health care setting to address the long-term medical and psychosocial needs of individuals with a history of childhood maltreatment

    Prehospital transdermal glyceryl trinitrate in patients with ultra-acute presumed stroke (RIGHT-2): an ambulance-based, randomised, sham-controlled, blinded, phase 3 trial

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    Background: High blood pressure is common in acute stroke and is a predictor of poor outcome; however, large trials of lowering blood pressure have given variable results, and the management of high blood pressure in ultra-acute stroke remains unclear. We investigated whether transdermal glyceryl trinitrate (GTN; also known as nitroglycerin), a nitric oxide donor, might improve outcome when administered very early after stroke onset. Methods: We did a multicentre, paramedic-delivered, ambulance-based, prospective, randomised, sham-controlled, blinded-endpoint, phase 3 trial in adults with presumed stroke within 4 h of onset, face-arm-speech-time score of 2 or 3, and systolic blood pressure 120 mm Hg or higher. Participants were randomly assigned (1:1) to receive transdermal GTN (5 mg once daily for 4 days; the GTN group) or a similar sham dressing (the sham group) in UK-based ambulances by paramedics, with treatment continued in hospital. Paramedics were unmasked to treatment, whereas participants were masked. The primary outcome was the 7-level modified Rankin Scale (mRS; a measure of functional outcome) at 90 days, assessed by central telephone follow-up with masking to treatment. Analysis was hierarchical, first in participants with a confirmed stroke or transient ischaemic attack (cohort 1), and then in all participants who were randomly assigned (intention to treat, cohort 2) according to the statistical analysis plan. This trial is registered with ISRCTN, number ISRCTN26986053. Findings: Between Oct 22, 2015, and May 23, 2018, 516 paramedics from eight UK ambulance services recruited 1149 participants (n=568 in the GTN group, n=581 in the sham group). The median time to randomisation was 71 min (IQR 45–116). 597 (52%) patients had ischaemic stroke, 145 (13%) had intracerebral haemorrhage, 109 (9%) had transient ischaemic attack, and 297 (26%) had a non-stroke mimic at the final diagnosis of the index event. In the GTN group, participants' systolic blood pressure was lowered by 5·8 mm Hg compared with the sham group (p<0·0001), and diastolic blood pressure was lowered by 2·6 mm Hg (p=0·0026) at hospital admission. We found no difference in mRS between the groups in participants with a final diagnosis of stroke or transient ischaemic stroke (cohort 1): 3 (IQR 2–5; n=420) in the GTN group versus 3 (2–5; n=408) in the sham group, adjusted common odds ratio for poor outcome 1·25 (95% CI 0·97–1·60; p=0·083); we also found no difference in mRS between all patients (cohort 2: 3 [2–5]; n=544, in the GTN group vs 3 [2–5]; n=558, in the sham group; 1·04 [0·84–1·29]; p=0·69). We found no difference in secondary outcomes, death (treatment-related deaths: 36 in the GTN group vs 23 in the sham group [p=0·091]), or serious adverse events (188 in the GTN group vs 170 in the sham group [p=0·16]) between treatment groups. Interpretation: Prehospital treatment with transdermal GTN does not seem to improve functional outcome in patients with presumed stroke. It is feasible for UK paramedics to obtain consent and treat patients with stroke in the ultra-acute prehospital setting

    Association of early nutritional status With child development in the Asia Pacific region

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    Importance: Stunting was used as a proxy for underdevelopment in early childhood in previous studies, but the associations between child development and other growth and body composition parameters were rarely studied. Objective: To estimate the association between malnutrition and early child development (ECD) at an individual level. Design, Setting, and Participants: This population-based, cross-sectional study used data from the East Asia Pacific Early Child Development Scales, a population-representative survey of children aged 3 to 5 years old, conducted in 2012 to 2014 in communities in Cambodia, China, Mongolia, Papua New Guinea, and Vanuatu. Data analysis was performed from November 2019 to April 2021. Exposures: Stunting (height-for-age [HFA] z score less than −2), wasting (weight-for-height z score less than −2), overweight (weight-for-height z score greater than 2), body mass index (BMI)–for-age z score, and body fat proportion based on existing growth standard and formula. Main Outcomes and Measures: ECD directly assessed using the validated East Asia–Pacific ECD Scales. Results: A total of 7108 children (3547 girls; mean [SD], age 4.48 [0.84] years) were included in this study. The prevalence of stunting was 27.1% (range across countries, 1.2%-55.0%), that of wasting was 13.7% (range, 5.4%-35.9%), and that of overweight was 15.9% (range, 2.2%-53.7%). Adjusted for country variations, age, sex, urbanicity, family socioeconomic status, and body fat proportion, ECD was linearly associated with HFA (β, 1.57; 95% CI, 1.35-1.80) and BMI-for-age (β, 0.64; 95% CI, 0.45-0.82). After adjustment for BMI and height, better ECD was associated with low body fat proportion (β, 0.93; 95% CI, 0.45-1.42). The association of HFA was more pronounced in Southeast Asia and the Pacific region than in East Asia, and the association of fat proportion was specific to children living in urban environments. Conclusions and Relevance: HFA, BMI-for-age, and body fat proportion were independently associated with ECD, and these findings suggest that future studies should consider using these parameters to estimate the prevalence of child underdevelopment; nutritional trials should examine to what extent the associations are causal
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