5,054 research outputs found

    Familial vasculitides: granulomatosis with polyangitis and microscopic polyangitis in two brothers with differing anti-neutrophil cytoplasm antibody specificity

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    Anti-neutrophil cytoplasm antibody (ANCA)-associated vasculitis (AAV) is a group of rare autoimmune diseases. Although the aetiology of AAV is uncertain, it is likely that genetic and environmental factors contribute. We report the unusual case of two brothers presenting with AAV with differing clinical pictures and differing ANCA specificity. There is a recently identified difference in genetic risk factors associated with ANCA specificity, making it surprising that first-degree relatives develop AAV with differing clinical and serological features. Our report illustrates the complex aetiology of AAV and suggests that further research on the interaction of genetic and environmental factors is needed

    Phase and Intensity Distributions of Individual Pulses of PSR B0950+08

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    The distribution of the intensities of individual pulses of PSR B0950+08 as a function of the longitudes at which they appear is analyzed. The flux density of the pulsar at 111 MHz varies strongly from day to day (by up to a factor of 13) due to the passage of the radiation through the interstellar plasma (interstellar scintillation). The intensities of individual pulses can exceed the amplitude of the mean pulse profile, obtained by accumulating 770 pulses, by more than an order of magnitude. The intensity distribution along the mean profile is very different for weak and strong pulses. The differential distribution function for the intensities is a power law with index n = -1.1 +- 0.06 up to peak flux densities for individual pulses of the order of 160 Jy

    Solar and Heliospheric Physics with the Square Kilometre Array

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    The fields of solar radiophysics and solar system radio physics, or radio heliophysics, will benefit immensely from an instrument with the capabilities projected for SKA. Potential applications include interplanetary scintillation (IPS), radio-burst tracking, and solar spectral radio imaging with a superior sensitivity. These will provide breakthrough new insights and results in topics of fundamental importance, such as the physics of impulsive energy releases, magnetohydrodynamic oscillations and turbulence, the dynamics of post-eruptive processes, energetic particle acceleration, the structure of the solar wind and the development and evolution of solar wind transients at distances up to and beyond the orbit of the Earth. The combination of the high spectral, time and spatial resolution and the unprecedented sensitivity of the SKA will radically advance our understanding of basic physical processes operating in solar and heliospheric plasmas and provide a solid foundation for the forecasting of space weather events.Comment: 15 pages, Proceedings of Advancing Astrophysics with the Square Kilometre Array (AASKA14). 9 -13 June, 2014. Giardini Naxos, Italy. Online at http://pos.sissa.it/cgi-bin/reader/conf.cgi?confid=215, id.16

    Atomic spectrometry update : a review of advances in environmental analysis

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    This is the 31st annual review of the application of atomic spectrometry to the chemical analysis of environmental samples. This update refers to papers published approximately between August 2014 and July 2015 and continues the series of Atomic Spectrometry Updates (ASUs) in Environmental Analysis that should be read in conjunction with other related ASUs in the series, namely: clinical and biological materials, foods and beverages; advances in atomic spectrometry and related techniques; elemental speciation; X-ray spectrometry; and metals, chemicals and functional materials. In the field of air analysis, highlights within this review period included: the development of a new laser fluorescence instrument for the ultratrace determination of mercury vapour; single particle ICP-MS studies and the coupling of elemental analysers to mass spectrometers for the improved characterisation of carbonaceous aerosols. In the arena of water analysis, methods continue to be developed: for the extraction and preconcentration of elements, As, Cr, Hg and Sb species and determination of elemental constituents in colloidal and NP fractions. Emerging elements of interest include Gd derived from MRI agents discharged at low level from medical facilities in water courses. Instrumental developments reported included the use of MC-ICP-MS for isotopic tracer studies and a review of TXRF techniques and associated preconcentration procedures for trace element analysis. In the period covered by this update several articles have explored the analysis of soil extracts for geochemical prospecting. There has been widening interest in the use of CS-AAS and in the application of techniques capable of direct sample analysis such as slurry sampling ETAAS and ETV-ICP-AES. Portable XRF instrumentation is now being used in many disciplines to quantify trace elements in soils – bringing a need for better transfer of analytical knowledge to non-specialist users – and the growing use of portable XRF in proximal sensing is also noteworthy. Recent research indicates that geological applications still drive many of the instrumental and methodological advances in LA-ICP-MS. Fundamental studies continued to shed light on the processes involved and hence ways of improving the analysis of laser-produced aerosols and to minimise matrix and fractionation effects. A new technique LA-DOF-MS (distance of flight) was described. The utility of LIBS and portable XRF for in situ survey work continues to show promise but issues such as appropriate calibration regimes and data processing protocols will still need to be addressed

    Self-replication and evolution of DNA crystals

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    Is it possible to create a simple physical system that is capable of replicating itself? Can such a system evolve interesting behaviors, thus allowing it to adapt to a wide range of environments? This paper presents a design for such a replicator constructed exclusively from synthetic DNA. The basis for the replicator is crystal growth: information is stored in the spatial arrangement of monomers and copied from layer to layer by templating. Replication is achieved by fragmentation of crystals, which produces new crystals that carry the same information. Crystal replication avoids intrinsic problems associated with template-directed mechanisms for replication of one-dimensional polymers. A key innovation of our work is that by using programmable DNA tiles as the crystal monomers, we can design crystal growth processes that apply interesting selective pressures to the evolving sequences. While evolution requires that copying occur with high accuracy, we show how to adapt error-correction techniques from algorithmic self-assembly to lower the replication error rate as much as is required

    The COVID-19 pandemic and international students: Consequences for researchers, stakeholders and policymakers in the mobility field

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    Since the early months of 2020, COVID-19 has had a profound impact on societies, transforming social, economic and political life throughout the European Union. This resulted in dramatic change in a central aspect of life for many Europeans: the freedom to circulate between countries for non-essential purposes, including tertiary education. This loss has created problems for EU citizens and others from third-party countries, who have found themselves cut off from essential support or the means to return home in a safe and timely manner. In this chapter, we take a look at this situation, with our research questions considering some of the most prominent impacts of the pandemic on internationalised learning for both intra-EU exchange students and extra-EU educational migrants. To illustrate the emerging challenges, we have conducted research with international students in Portugal during the initial months of the public health emergency, from which we were able to identify issues that may be of concern to researchers, stakeholders and policymakers in the mobility field.info:eu-repo/semantics/publishedVersio

    Simulations of Electron Acceleration at Collisionless Shocks: The Effects of Surface Fluctuations

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    Energetic electrons are a common feature of interplanetary shocks and planetary bow shocks, and they are invoked as a key component of models of nonthermal radio emission, such as solar radio bursts. A simulation study is carried out of electron acceleration for high Mach number, quasi-perpendicular shocks, typical of the shocks in the solar wind. Two dimensional self-consistent hybrid shock simulations provide the electric and magnetic fields in which test particle electrons are followed. A range of different shock types, shock normal angles, and injection energies are studied. When the Mach number is low, or the simulation configuration suppresses fluctuations along the magnetic field direction, the results agree with theory assuming magnetic moment conserving reflection (or Fast Fermi acceleration), with electron energy gains of a factor only 2 - 3. For high Mach number, with a realistic simulation configuration, the shock front has a dynamic rippled character. The corresponding electron energization is radically different: Energy spectra display: (1) considerably higher maximum energies than Fast Fermi acceleration; (2) a plateau, or shallow sloped region, at intermediate energies 2 - 5 times the injection energy; (3) power law fall off with increasing energy, for both upstream and downstream particles, with a slope decreasing as the shock normal angle approaches perpendicular; (4) sustained flux levels over a broader region of shock normal angle than for adiabatic reflection. All these features are in good qualitative agreement with observations, and show that dynamic structure in the shock surface at ion scales produces effective scattering and can be responsible for making high Mach number shocks effective sites for electron acceleration.Comment: 26 pages, 12 figure

    Consequences of sexual harassment in sport for female athletes

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    Sexual harassment research was first undertaken in the workplace and educational settings. Research on sexual harassment in sport is scarce but has grown steadily since the mid-1980s. Even so, very little is known about the causes and/or characteristics and/or consequences of sexual harassment in sport settings. This article reports on the findings from interviews with 25 elite female athletes in Norway who indicated in a prior survey (N =572) that they had experienced sexual harassment from someone in sport. The consequences of the incidents of sexual harassment that were reported were mostly negative, but some also reported that their experiences of sexual harassment had had no consequences for them. “Thinking about the incidents”, a “destroyed relationship to the coach”, and “more negative view of men in general” were the most often negative consequences mentioned. In addition, a surprising number had chosen to move to a different sport or to drop out of elite sport altogether because of the harassment
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