574 research outputs found

    Microstructural control and optimization of Haynes 282 manufactured through laser powder bed fusion

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    The microstructure and properties of alloy Haynes 282 produced through laser powder bed fusion were investigated as a function of the post-deposition heat-treatment. Scanning electron microscopy and X-ray diffraction were utilized to characterize the microstructure, whilst electro-thermal mechanical testing was used to evaluate the tensile and creep properties at 900 °C. In the as-deposited state, the initial microstructure consisted of the γ and γʹ phases along with M6C and M23C6 carbides. These carbides were observed to govern the recrystallization behaviour of the material and resulted in a minimum recrystallization temperature of 1240 °C. Following post-deposition heat-treatments, the microstructures consisted of a monomodal distribution of γʹ with M6C and M23C6 carbides along the grain boundaries. Tertiary γʹ particles were found to form in the vicinity of carbides in samples that employed a γʹ super-solvus step prior to ageing at 788 °C. The tensile properties were found to be similar in all heat-treated states, consistent with the minimal differences observed in the microstructures. In contrast, significant differences in the creep behaviour of the alloy were observed following the different heat-treatments, although no correlation with the microstructures was observed

    An Early-warning System for Electromagnetic Follow-up of Gravitational-wave Events

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    Binary neutron stars (BNSs) will spend ≃10–15 minutes in the band of Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO) and Virgo detectors at design sensitivity. Matched-filtering of gravitational-wave (GW) data could in principle accumulate enough signal-to-noise ratio (S/N) to identify a forthcoming event tens of seconds before the companions collide and merge. Here we report on the design and testing of an early-warning GW detection pipeline. Early-warning alerts can be produced for sources that are at low enough redshift so that a large enough S/N accumulates ~10–60 s before merger. We find that about 7% (49%) of the total detectable BNS mergers will be detected 60 s (10 s) before the merger. About 2% of the total detectable BNS mergers will be detected before merger and localized to within 100 deg² (90% credible interval). Coordinated observing by several wide-field telescopes could capture the event seconds before or after the merger. LIGO–Virgo detectors at design sensitivity could facilitate observing at least one event at the onset of merger

    Multiple and Multidimensional life transitions in the context of life-limiting health conditions:Longitudinal study focussing on perspectives of Young Adults, Families and Professionals

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    Background: There is a dearth of literature that investigates life transitions of young adults (YAs) with life-limiting conditions, families and professionals. The scant literature that is available has methodological limitations, including not listening to the voice of YAs, collecting data retrospectively, at one time point, from one group’s perspective and single case studies. The aim of this study was to address the gaps found in our literature review and provide a clearer understanding of the multiple and multi-dimensional life transitions experienced by YAs and significant others, over a period of time. Methods: This qualitative study used a longitudinal design and data were collected using semi-structured interviews over a 6-month period at 3 time points. Participants included 12 YAs with life-limiting conditions and their nominated significant others (10 family members and 11 professionals). Data were analysed using a thematic analysis approach. Results: Life transitions of YA and significant others are complex; they experience multiple and multi-dimensional transitions across several domains. The findings challenge the notion that all life transitions are triggered by health transitions of YAs, and has highlighted environmental factors (attitudinal and systemic) that can be changed to facilitate smoother transitions in various aspects of their lives. Conclusions: This study makes a unique and significant contribution to literature. It provides evidence and rich narratives for policy makers and service providers to change policies and practices that are in line with the needs of YAs with life-limiting conditions as they transition to adulthood. Families and professionals have specific training needs that have not yet been met fully

    An early warning system for electromagnetic follow-up of gravitational-wave events

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    Binary neutron stars (BNSs) will spend 10\simeq 10 -- 15 minutes in the band of Advanced LIGO and Virgo detectors at design sensitivity. Matched-filtering of gravitational-wave (GW) data could in principle accumulate enough signal-to-noise ratio (SNR) to identify a forthcoming event tens of seconds before the companions collide and merge. Here we report on the design and testing of an early warning gravitational-wave detection pipeline. Early warning alerts can be produced for sources that are at low enough redshift so that a large enough SNR accumulates 1060s\sim 10 - 60\,\rm s before merger. We find that about 7% (respectively, 49%) of the total detectable BNS mergers will be detected 60s60\, \rm s (10s10\, \rm s) before the merger. About 2% of the total detectable BNS mergers will be detected before merger and localized to within 100deg2100\, \rm \text{deg}^2 (90% credible interval). Coordinated observing by several wide-field telescopes could capture the event seconds before or after the merger. LIGO-Virgo detectors at design sensitivity could facilitate observing at least one event at the onset of merger.Comment: small update in numbers caused by using a more updated local BNS rate estimat

    Chinese Americans’ Views and Use of Family Health History: A Qualitative Study

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    Objective Family health history (FHH) plays a significant role in early disease detection and preven- tion. Although Asian Americans are the fastest growing U.S. immigrant group, no data exists regarding Chinese Americans’ (the largest Asian subgroup) views and use of FHH. This study examines this important issue. Methods Forty-nine adults from southern U.S. Chinese American communities participated in this qualitative, semi-structured, in-depth interview study. Interviews were audio recorded, tran- scribed, and analyzed with a content analysis approach. Results Although the majority of participants perceived the importance of collecting FHH, most lacked FHH knowledge and failed to collect FHH information. Barriers affecting FHH collec- tion and discussion among family members included long-distance separation from family members, self-defined “healthy family,� and Chinese cultural beliefs. Lack of doctors’ inqui- ries, never/rarely visiting physicians, self-defined “healthy family,� perceived insignificance of discussing FHH with doctors, and Chinese cultural beliefs were the obstacles in commu- nicating FHH with physicians. Conclusions Chinese Americans had limited usage of their FHH and faced cultural, distance, knowl- edge-, and healthcare system-related barriers that influenced their FHH use. Developing FHH education programs for Chinese Americans is highly recommended

    Identifying the Age Cohort Responsible for Transmission in a Natural Outbreak of Bordetella bronchiseptica

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    Identifying the major routes of disease transmission and reservoirs of infection are needed to increase our understanding of disease dynamics and improve disease control. Despite this, transmission events are rarely observed directly. Here we had the unique opportunity to study natural transmission of Bordetella bronchiseptica – a directly transmitted respiratory pathogen with a wide mammalian host range, including sporadic infection of humans – within a commercial rabbitry to evaluate the relative effects of sex and age on the transmission dynamics therein. We did this by developing an a priori set of hypotheses outlining how natural B. bronchiseptica infections may be transmitted between rabbits. We discriminated between these hypotheses by using force-of-infection estimates coupled with random effects binomial regression analysis of B. bronchiseptica age-prevalence data from within our rabbit population. Force-of-infection analysis allowed us to quantify the apparent prevalence of B. bronchiseptica while correcting for age structure. To determine whether transmission is largely within social groups (in this case litter), or from an external group, we used random-effect binomial regression to evaluate the importance of social mixing in disease spread. Between these two approaches our results support young weanlings – as opposed to, for example, breeder or maternal cohorts – as the age cohort primarily responsible for B. bronchiseptica transmission. Thus age-prevalence data, which is relatively easy to gather in clinical or agricultural settings, can be used to evaluate contact patterns and infer the likely age-cohort responsible for transmission of directly transmitted infections. These insights shed light on the dynamics of disease spread and allow an assessment to be made of the best methods for effective long-term disease control

    Gene Expression Studies in Major Depression

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    The dramatic technical advances in methods to measure gene expression on a genome-wide level thus far have not been paralleled by breakthrough discoveries in psychiatric disorders—including major depression (MD)—using these hypothesis-free approaches. In this review, we first describe the methodologic advances made in gene expression analysis, from quantitative polymerase chain reaction to next-generation sequencing. We then discuss issues in gene expression experiments specific to MD, ranging from the choice of target tissues to the characterization of the case group. We provide a synopsis of the gene expression studies published thus far for MD, with a focus on studies using mRNA microarray methods. Finally, we discuss possible new strategies for the gene expression studies in MD that circumvent some of the addressed issues

    Finishing the euchromatic sequence of the human genome

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    The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead
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