307 research outputs found

    Qweak: A Precision Measurement of the Proton's Weak Charge

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    The Qweak experiment at Jefferson Lab aims to make a 4% measurement of the parity-violating asymmetry in elastic scattering at very low Q2Q^2 of a longitudinally polarized electron beam on a proton target. The experiment will measure the weak charge of the proton, and thus the weak mixing angle at low energy scale, providing a precision test of the Standard Model. Since the value of the weak mixing angle is approximately 1/4, the weak charge of the proton Qwp=14sin2θwQ_w^p = 1-4 \sin^2 \theta_w is suppressed in the Standard Model, making it especially sensitive to the value of the mixing angle and also to possible new physics. The experiment is approved to run at JLab, and the construction plan calls for the hardware to be ready to install in Hall C in 2007. The theoretical context of the experiment and the status of its design are discussed.Comment: 5 pages, 2 figures, LaTeX2e, to be published in CIPANP 2003 proceeding

    Are all beliefs equal? Implicit belief attributions recruiting core brain regions of theory of mind

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    Humans possess efficient mechanisms to behave adaptively in social contexts. They ascribe goals and beliefs to others and use these for behavioural predictions. Researchers argued for two separate mental attribution systems: an implicit and automatic one involved in online interactions, and an explicit one mainly used in offline deliberations. However, the underlying mechanisms of these systems and the types of beliefs represented in the implicit system are still unclear. Using neuroimaging methods, we show that the right temporo-parietal junction and the medial prefrontal cortex, brain regions consistently found to be involved in explicit mental state reasoning, are also recruited by spontaneous belief tracking. While the medial prefrontal cortex was more active when both the participant and another agent believed an object to be at a specific location, the right temporo-parietal junction was selectively activated during tracking the false beliefs of another agent about the presence, but not the absence of objects. While humans can explicitly attribute to a conspecific any possible belief they themselves can entertain, implicit belief tracking seems to be restricted to beliefs with specific contents, a content selectivity that may reflect a crucial functional characteristic and signature property of implicit belief attribution

    The Small Satellite-Based, Imaging X-Ray Polarimeter Explorer (IXPE) Mission

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    The Imaging X-ray Polarimeter Explorer (IXPE) focuses on high energy astrophysics in the 2—8 keV x-ray band. IXPE is designed to explore general relativistic and quantum physics effects of gravity, energy, electric and magnetic fields at extreme limits. IXPE, a NASA Small Explorer (SMEX) Mission, will add new dimensions to on-orbit x-ray science: polarization degree, polarization angle and extended object polarization imaging. Polarization uniquely probes physical anisotropies that are not otherwise measurable—ordered magnetic fields, aspheric matter distributions, or general relativistic coupling to black-hole spin. Detailed imaging enables the specific properties of extended x-ray sources to be differentiated. The IXPE Observatory consists of spacecraft and payload modules built up in parallel to form the Observatory during system integration and test. The payload includes three polarization-sensitive, x-ray detector arrays paired with three x-ray mirror module assemblies (MMA). A deployable boom provides the correct separation (focal length) between the detector units and MMAs. Currently, the boom has been delivered, all four detectors units (DU) are complete, the detectors service unit (DSU) is complete, instrument system testing has been completed (DSU with 3 DUs), three of four MMAs is built and all spacecraft components except the solar array have been delivered along with the spacecraft and payload structures. Payload and spacecraft integration and test (I&T) started in March 2020. This paper overviews the flight segment (the Observatory, payload, and spacecraft implementation concepts) with emphasis on the build status and summarizes the launch segment. Launch is planned to occur on a Falcon 9 launch vehicle during Summer 2021. The paper summarizes the impacts of switching from the ‘design-to baseline’ of Pegasus XL to the selected launch vehicle for flight, Falcon 9. COVID-19 impacts to the Project are also summarized. The paper will close with a summary of the mission development status. The Project is firmly into the build phase for both the spacecraft and payload and rapidly approaching Observatory I&T

    The burden of childhood atopic dermatitis in the primary care setting: a report from the Meta-LARC Consortium

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    Background: Little is known about the burden of AD encountered in U.S. primary care practices and the frequency and type of skin care practices routinely used in children. Objectives: To estimate the prevalence of AD and allergic comorbidities in children 0-5 years attending primary care practices in the U.S. and to describe routine skin care practices used in this population. Design: A cross-sectional survey study of a convenience sample of children under the age of 5 attending primary care practices for any reason. Setting: Ten primary care practices in five U.S. states.Results: Amongst 652 children attending primary care practices, the estimated prevalence of ever having AD was 24 % (95% CI= 21-28) ranging from 15% among those under the age of one to 38% among those aged 4- 5 years. The prevalence of comorbid asthma was higher among AD participants compared to those with no AD, 12% and 4%, respectively (p less than 0.001). Moisturizers with high water:oil ratios were most commonly used (i.e., lotions) in the non-AD population, whereas moisturizers with low water:oil content (i.e. ointments) most common when AD was present. Conclusions: Our study found a large burden of AD in the primary care practice setting in the U.S. The majority of households reported skin care practices in children without AD that may be detrimental to the skin barrier such as frequent bathing and the routine use of moisturizers with high water: oil ratios. Clinical trials are needed to identify which skin care practices are optimal for reducing the significant risk of AD in the community

    Insights into the Management of Emerging Infections: Regulating Variant Creutzfeldt-Jakob Disease Transfusion Risk in the UK and the US

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    BACKGROUND: Variant Creutzfeldt-Jakob disease (vCJD) is a human prion disease caused by infection with the agent of bovine spongiform encephalopathy. After the recognition of vCJD in the UK in 1996, many nations implemented policies intended to reduce the hypothetical risk of transfusion transmission of vCJD. This was despite the fact that no cases of transfusion transmission had yet been identified. In December 2003, however, the first case of vCJD in a recipient of blood from a vCJD-infected donor was announced. The aim of this study is to ascertain and compare the factors that influenced the motivation for and the design of regulations to prevent transfusion transmission of vCJD in the UK and US prior to the recognition of this case. METHODS AND FINDINGS: A document search was conducted to identify US and UK governmental policy statements and guidance, transcripts (or minutes when transcripts were not available) of scientific advisory committee meetings, research articles, and editorials published in medical and scientific journals on the topic of vCJD and blood transfusion transmission between March 1996 and December 2003. In addition, 40 interviews were conducted with individuals familiar with the decision-making process and/or the science involved. All documents and transcripts were coded and analyzed according to the methods and principles of grounded theory. Data showed that while resulting policies were based on the available science, social and historical factors played a major role in the motivation for and the design of regulations to protect against transfusion transmission of vCJD. First, recent experience with and collective guilt resulting from the transfusion-transmitted epidemics of HIV/AIDS in both countries served as a major, historically specific impetus for such policies. This history was brought to bear both by hemophilia activists and those charged with regulating blood products in the US and UK. Second, local specificities, such as the recall of blood products for possible vCJD contamination in the UK, contributed to a greater sense of urgency and a speedier implementation of regulations in that country. Third, while the results of scientific studies played a prominent role in the construction of regulations in both nations, this role was shaped by existing social and professional networks. In the UK, early focus on a European study implicating B-lymphocytes as the carrier of prion infectivity in blood led to the introduction of a policy that requires universal leukoreduction of blood components. In the US, early focus on an American study highlighting the ability of plasma to serve as a reservoir of prion infectivity led the FDA and its advisory panel to eschew similar measures. CONCLUSIONS: The results of this study yield three important theoretical insights that pertain to the global management of emerging infectious diseases. First, because the perception and management of disease may be shaped by previous experience with disease, especially catastrophic experience, there is always the possibility for over-management of some possible routes of transmission and relative neglect of others. Second, local specificities within a given nation may influence the temporality of decision making, which in turn may influence the choice of disease management policies. Third, a preference for science-based risk management among nations will not necessarily lead to homogeneous policies. This is because the exposure to and interpretation of scientific results depends on the existing social and professional networks within a given nation. Together, these theoretical insights provide a framework for analyzing and anticipating potential conflicts in the international management of emerging infectious diseases. In addition, this study illustrates the utility of qualitative methods in investigating research questions that are difficult to assess through quantitative means

    The deuteron: structure and form factors

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    A brief review of the history of the discovery of the deuteron in provided. The current status of both experiment and theory for the elastic electron scattering is then presented.Comment: 80 pages, 33 figures, submited to Advances in Nuclear Physic

    The Scottish Bladder Cancer Quality Performance Indicators Influencing Outcomes, Prognosis, and Surveillance (Scot BC Quality OPS) Clinical Project

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    The aim of the Scot BC Quality OPS clinical project is to create a reliable prospective data set for evaluating real-world effectiveness and efficiency consequent to standardisation and monitoring of bladder cancer treatment (through the national Quality Performance Indicator programme) and streamlined surveillance in Scotland. Several work packages have been created, reflecting wide clinical and research collaboration

    A Bronze Age Round Barrow Cemetery, Pit Alignments, Iron Age Burials, Iron Age Copper Working, and Later Activity at Four Crosses, Llandysilio, Powys.

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    Excavation undertaken at the Upper Severn valley round barrow cemetery at Four Crosses, Llandysilio between 2004 and 2006 has increased the known barrows and ring-ditches to some 26 monuments, and revealed additional burials. Based on limited dating evidence, and the data from earlier excavations, the majority of the barrows are thought to be constructed in the Bronze Age. The barrows are part of a larger linear cemetery and the landscape setting and wider significance of this linear barrow cemetery are explored within this report. Dating suggests two barrows were later, Iron Age additions. The excavation also investigated Iron Age and undated pit alignments, Middle Iron Age copper working and a small Romano-British inhumation cemetery and field systems. Much of this evidence reflects the continuing importance of the site for ritual and funerary activity

    The Imaging X-ray Polarimetry Explorer (IXPE): Technical Overview

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    The Imaging X-ray Polarimetry Explorer (IXPE) will expand the information space for study of cosmic sources, by adding linear polarization to the properties (time, energy, and position) observed in x-ray astronomy. Selected in 2017 January as a NASA Astrophysics Small Explorer (SMEX) mission, IXPE will be launched into an equatorial orbit in 2021. The IXPE mission will provide scientifically meaningful measurements of the x-ray polarization of a few dozen sources in the 2-8 keV band, including polarization maps of several x-ray-bright extended sources and phase-resolved polarimetry of many bright pulsating x-ray sources
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