170 research outputs found

    New Measurement of Parity Violation in Elastic Electron-Proton Scattering and Implications for Strange Form Factors

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    We have measured the parity-violating electroweak asymmetry in the elastic scattering of polarized electrons from the proton. The result is A = -15.05 +- 0.98(stat) +- 0.56(syst) ppm at the kinematic point theta_lab = 12.3 degrees and Q^2 = 0.477 (GeV/c)^2. The measurement implies that the value for the strange form factor (G_E^s + 0.392 G_M^s) = 0.025 +- 0.020 +- 0.014, where the first error is experimental and the second arises from the uncertainties in electromagnetic form factors. This measurement is the first fixed-target parity violation experiment that used either a `strained' GaAs photocathode to produce highly polarized electrons or a Compton polarimeter to continuously monitor the electron beam polarization.Comment: 8 pages, 4 figures, Tex, elsart.cls; revised version as accepted for Phys. Lett.

    Display of probability densities for data from a continuous distribution

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    Based on cumulative distribution functions, Fourier series expansion and Kolmogorov tests, we present a simple method to display probability densities for data drawn from a continuous distribution. It is often more efficient than using histograms.Comment: 5 pages, 4 figures, presented at Computer Simulation Studies XXIV, Athens, GA, 201

    Radio Emission from Ultra-Cool Dwarfs

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    The 2001 discovery of radio emission from ultra-cool dwarfs (UCDs), the very low-mass stars and brown dwarfs with spectral types of ~M7 and later, revealed that these objects can generate and dissipate powerful magnetic fields. Radio observations provide unparalleled insight into UCD magnetism: detections extend to brown dwarfs with temperatures <1000 K, where no other observational probes are effective. The data reveal that UCDs can generate strong (kG) fields, sometimes with a stable dipolar structure; that they can produce and retain nonthermal plasmas with electron acceleration extending to MeV energies; and that they can drive auroral current systems resulting in significant atmospheric energy deposition and powerful, coherent radio bursts. Still to be understood are the underlying dynamo processes, the precise means by which particles are accelerated around these objects, the observed diversity of magnetic phenomenologies, and how all of these factors change as the mass of the central object approaches that of Jupiter. The answers to these questions are doubly important because UCDs are both potential exoplanet hosts, as in the TRAPPIST-1 system, and analogues of extrasolar giant planets themselves.Comment: 19 pages; submitted chapter to the Handbook of Exoplanets, eds. Hans J. Deeg and Juan Antonio Belmonte (Springer-Verlag

    Physics of Neutron Star Crusts

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    The physics of neutron star crusts is vast, involving many different research fields, from nuclear and condensed matter physics to general relativity. This review summarizes the progress, which has been achieved over the last few years, in modeling neutron star crusts, both at the microscopic and macroscopic levels. The confrontation of these theoretical models with observations is also briefly discussed.Comment: 182 pages, published version available at <http://www.livingreviews.org/lrr-2008-10

    Discovery of Radio Emission from the Brown Dwarf LP944-20

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    Brown dwarfs are classified as objects which are not massive enough to sustain nuclear fusion of hydrogen, and are distinguished from planets by their ability to burn deuterium. Old (>10 Myr) brown dwarfs are expected to possess short-lived magnetic fields and, since they no longer generate energy from collapse and accretion, weak radio and X-ray emitting coronae. Several efforts have been undertaken in the past to detect chromospheric activity from the brown dwarf LP944-20 at X-ray and optical wavelengths, but only recently an X-ray flare from this object was detected. Here we report on the discovery of quiescent and flaring radio emission from this source, which represents the first detection of persistent radio emission from a brown dwarf, with luminosities that are several orders of magnitude larger than predicted from an empirical relation between the X-ray and radio luminosities of many stellar types. We show in the context of synchrotron emission, that LP944-20 possesses an unusually weak magnetic field in comparison to active dwarf M stars, which might explain the null results from previous optical and X-ray observations of this source, and the deviation from the empirical relations.Comment: Accepted to Natur

    Identification of symptom and functional domains that fibromyalgia patients would like to see improved: a cluster analysis

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    <p>Abstract</p> <p>Background</p> <p>The purpose of this study was to determine whether some of the clinical features of fibromyalgia (FM) that patients would like to see improved aggregate into definable clusters.</p> <p>Methods</p> <p>Seven hundred and eighty-eight patients with clinically confirmed FM and baseline pain ≥40 mm on a 100 mm visual analogue scale ranked 5 FM clinical features that the subjects would most like to see improved after treatment (one for each priority quintile) from a list of 20 developed during focus groups. For each subject, clinical features were transformed into vectors with rankings assigned values 1-5 (lowest to highest ranking). Logistic analysis was used to create a distance matrix and hierarchical cluster analysis was applied to identify cluster structure. The frequency of cluster selection was determined, and cluster importance was ranked using cluster scores derived from rankings of the clinical features. Multidimensional scaling was used to visualize and conceptualize cluster relationships.</p> <p>Results</p> <p>Six clinical features clusters were identified and named based on their key characteristics. In order of selection frequency, the clusters were Pain (90%; 4 clinical features), Fatigue (89%; 4 clinical features), Domestic (42%; 4 clinical features), Impairment (29%; 3 functions), Affective (21%; 3 clinical features), and Social (9%; 2 functional). The "Pain Cluster" was ranked of greatest importance by 54% of subjects, followed by Fatigue, which was given the highest ranking by 28% of subjects. Multidimensional scaling mapped these clusters to two dimensions: Status (bounded by Physical and Emotional domains), and Setting (bounded by Individual and Group interactions).</p> <p>Conclusion</p> <p>Common clinical features of FM could be grouped into 6 clusters (Pain, Fatigue, Domestic, Impairment, Affective, and Social) based on patient perception of relevance to treatment. Furthermore, these 6 clusters could be charted in the 2 dimensions of Status and Setting, thus providing a unique perspective for interpretation of FM symptomatology.</p

    Comparative Omics-Driven Genome Annotation Refinement: Application across Yersiniae

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    Genome sequencing continues to be a rapidly evolving technology, yet most downstream aspects of genome annotation pipelines remain relatively stable or are even being abandoned. The annotation process is now performed almost exclusively in an automated fashion to balance the large number of sequences generated. One possible way of reducing errors inherent to automated computational annotations is to apply data from omics measurements (i.e. transcriptional and proteomic) to the un-annotated genome with a proteogenomic-based approach. Here, the concept of annotation refinement has been extended to include a comparative assessment of genomes across closely related species. Transcriptomic and proteomic data derived from highly similar pathogenic Yersiniae (Y. pestis CO92, Y. pestis Pestoides F, and Y. pseudotuberculosis PB1/+) was used to demonstrate a comprehensive comparative omic-based annotation methodology. Peptide and oligo measurements experimentally validated the expression of nearly 40% of each strain's predicted proteome and revealed the identification of 28 novel and 68 incorrect (i.e., observed frameshifts, extended start sites, and translated pseudogenes) protein-coding sequences within the three current genome annotations. Gene loss is presumed to play a major role in Y. pestis acquiring its niche as a virulent pathogen, thus the discovery of many translated pseudogenes, including the insertion-ablated argD, underscores a need for functional analyses to investigate hypotheses related to divergence. Refinements included the discovery of a seemingly essential ribosomal protein, several virulence-associated factors, a transcriptional regulator, and many hypothetical proteins that were missed during annotation

    Social Relationships and Mortality Risk: A Meta-analytic Review

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    In a meta-analysis, Julianne Holt-Lunstad and colleagues find that individuals' social relationships have as much influence on mortality risk as other well-established risk factors for mortality, such as smoking

    Persons living with AIDS in nurses' social representations: analysis of central, contranormative and attitudinal elements

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    OBJECTIVES: to describe and analyze the centrality, the mute zone and the attitudes expressed in nurses' social representations of people with Human Immunodeficiency Virus. METHOD: the subjects were 30 nurses from a university hospital in Rio de Janeiro. The data was collected using a Likert scale. RESULTS: the data pointed to a process of representational change regarding Human Immunodeficiency Virus / Acquired Immunodeficiency Syndrome, with the assumption of a more positive attitude regarding living with this health issue. The hypothesis of the existence of a mute zone in the representation, comprising elements with a contranormative character, was strengthened. CONCLUSION: the influence of the dynamics of social normativity on how the social representations studied are expressed may contribute to a better understanding of its structuring process. It also helps in the analysis of possible gaps among the nurses' discourses and practices in relation to Human Immunodeficiency Virus / Acquired Immunodeficiency Syndrome.OBJETIVOS: describir y analizar la centralidad, la zona muda y las actitudes expresas en las representaciones sociales de enfermeros acerca de la persona con Virus de la Inmunodeficiencia Humana. MÉTODO: los sujetos fueron 30 enfermeros de un hospital universitario de Rio de Janeiro. Los datos fueron colectados utilizando escala tipo likert. RESULTADOS: indicaron un proceso de cambio representacional sobre el Virus de la Inmunodeficiencia Humana/Síndrome da Inmunodeficiencia Adquirida, con la Asunción de actitud más positiva sobre la convivencia con éste agravo. Fue reforzada hipótesis de existencia de zona muda en la representación compuesta por elementos de carácter contra normativo. CONCLUSIÓN: la influencia de la dinámica de normatividad social sobre el modo de expresión de las representaciones sociales estudiadas puede aportar para una mejor comprensión de su proceso de estructuración. Auxilia, también, en el análisis de eventuales desfases entre los discursos y las prácticas de los enfermeros con relación al Virus de la Inmunodeficiencia Humana/Síndrome da Inmunodeficiencia Adquirida.OBJETIVOS: descrever e analisar a centralidade, a zona muda e as atitudes expressas nas representações sociais de enfermeiros, acerca da pessoa com vírus da imunodeficiência humana. MÉTODO: os sujeitos foram 30 enfermeiros de um hospital universitário do Rio de Janeiro. Os dados foram coletados utilizando escala tipo Likert. RESULTADOS: os resultados indicaram um processo de mudança representacional sobre o vírus da imunodeficiência humana/síndrome da imunodeficiência adquirida, com a assunção de atitude mais positiva sobre a convivência com esse agravo. Foi reforçada a hipótese da existência de zona muda na representação composta por elementos de caráter contranormativo. CONCLUSÃO: a influência da dinâmica de normatividade social sobre o modo de expressão das representações sociais estudadas pode contribuir para melhor compreensão do seu processo de estruturação. Auxilia, também, na análise de eventuais defasagens entre os discursos e as práticas dos enfermeiros em relação ao vírus da imunodeficiência humana/síndrome da imunodeficiência adquirida

    A mixed methods pilot study with a cluster randomized control trial to evaluate the impact of a leadership intervention on guideline implementation in home care nursing

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    Abstract Background Foot ulcers are a significant problem for people with diabetes. Comprehensive assessments of risk factors associated with diabetic foot ulcer are recommended in clinical guidelines to decrease complications such as prolonged healing, gangrene and amputations, and to promote effective management. However, the translation of clinical guidelines into nursing practice remains fragmented and inconsistent, and a recent homecare chart audit showed less than half the recommended risk factors for diabetic foot ulcers were assessed, and peripheral neuropathy (the most significant predictor of complications) was not assessed at all. Strong leadership is consistently described as significant to successfully transfer guidelines into practice. Limited research exists however regarding which leadership behaviours facilitate and support implementation in nursing. The purpose of this pilot study is to evaluate the impact of a leadership intervention in community nursing on implementing recommendations from a clinical guideline on the nursing assessment and management of diabetic foot ulcers. Methods Two phase mixed methods design is proposed (ISRCTN 12345678). Phase I: Descriptive qualitative to understand barriers to implementing the guideline recommendations, and to inform the intervention. Phase II: Matched pair cluster randomized controlled trial (n = 4 centers) will evaluate differences in outcomes between two implementation strategies. Primary outcome: Nursing assessments of client risk factors, a composite score of 8 items based on Diabetes/Foot Ulcer guideline recommendations. Intervention: In addition to the organization's 'usual' implementation strategy, a 12 week leadership strategy will be offered to managerial and clinical leaders consisting of: a) printed materials, b) one day interactive workshop to develop a leadership action plan tailored to barriers to support implementation; c) three post-workshop teleconferences. Discussion This study will provide vital information on which leadership strategies are well received to facilitate and support guideline implementation. The anticipated outcomes will provide information to assist with effective management of foot ulcers for people with diabetes. By tracking clinical outcomes associated with guideline implementation, health care administrators will be better informed to influence organizational and policy decision-making to support evidence-based quality care. Findings will be useful to inform the design of future multi-centered trials on various clinical topics to enhance knowledge translation for positive outcomes. Trial Registration Current Control Trials ISRCTN0691089
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