468 research outputs found

    Research on refurbishable thermostructural panels for manned lifting entry vehicles

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    Refurbishable composite thermostructural heat shield panels for manned lifting entry vehicle

    The Search Coil Magnetometer for THEMIS

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    International audienceTHEMIS instruments incorporate a tri-axial Search Coil Magnetometer (SCM) designed to measure the magnetic components of waves associated with substorm breakup and expansion. The three search coil antennas cover the same frequency bandwidth, from 0.1 Hz to 4 kHz, in the ULF/ELF frequency range. They extend, with appropriate Noise Equivalent Magnetic Induction (NEMI) and sufficient overlap, the measurements of the fluxgate magnetometers. The NEMI of the searchcoil antennas and associated pre-amplifiers is smaller than 0.76 pT/ p Hz at 10 Hz.The analog signals produced by the searchcoils and associated preamplifiers are digitized and processed inside the IDPU, together with data from the EFI instrument. Searchcoil telemetry includes waveform transmission, FFT processed data, and data from a filter bank. The frequency range covered in waveform depends on the available telemetry. The searchcoils and their three axis structures have been precisely calibrated in a quiet site, and the calibration of the transfer function is checked on board usually once per orbit. The tri-axial searchcoils implemented on the five THEMIS spacecraft are working nominally

    Hot and dry conditions predict shorter nestling telomeres in an endangered songbird:Implications for population persistence

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    Climate warming is increasingly exposing wildlife to sublethal high temperatures, which may lead to chronic impacts and reduced fitness. Telomere length (TL) may link heat exposure to fitness, particularly at early-life stages, because developing organisms are especially vulnerable to adverse conditions, adversity can shorten telomeres, and TL predicts fitness. Here, we quantify how climatic and environmental conditions during early life are associated with TL in nestlings of wild purple-crowned fairy-wrens (Malurus coronatus), endangered songbirds of the monsoonal tropics. We found that higher average maximum air temperature (range 31 to 45 °C) during the nestling period was associated with shorter early-life TL. This effect was mitigated by water availability (i.e., during the wet season, with rainfall), but independent of other pertinent environmental conditions, implicating a direct effect of heat exposure. Models incorporating existing information that shorter early-life TL predicts shorter lifespan and reduced fitness showed that shorter TL under projected warming scenarios could lead to population decline across plausible future water availability scenarios. However, if TL is assumed to be an adaptive trait, population viability could be maintained through evolution. These results are concerning because the capacity to change breeding phenology to coincide with increased water availability appears limited, and the evolutionary potential of TL is unknown. Thus, sublethal climate warming effects early in life may have repercussions beyond individual fitness, extending to population persistence. Incorporating the delayed reproductive costs associated with sublethal heat exposure early in life is necessary for understanding future population dynamics with climate change

    HerMES: the rest-frame UV emission and a lensing model for the z= 6.34 luminous dusty starburst galaxy HFLS3

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    We discuss the rest-frame ultraviolet emission from the starbursting galaxy HFLS3 at a redshift of 6.34. The galaxy was discovered in Herschel/SPIRE data due to its red color in the submillimeter wavelengths from 250 to 500 ÎŒm. Keck/NIRC2 K s -band adaptive optics imaging data showed two potential near-IR counterparts near HFLS3. Previously, the northern galaxy was taken to be in the foreground at z = 2.1, while the southern galaxy was assumed to be HFLS3's near-IR counterpart. The recently acquired Hubble/WFC3 and Advanced Camera for Surveys (ACS) imaging data show conclusively that both optically bright galaxies are in the foreground at z < 6. A new lensing model based on the Hubble imaging data and the millimeter-wave continuum emission yields a magnification factor of 2.2 ± 0.3, with a 95% confidence upper limit on the magnification of 3.5. When corrected for lensing, the instantaneous star formation rate is 1320 M ☉ yr–1, with the 95% confidence lower limit around 830 M ☉ yr–1. The dust and stellar masses of HFLS3 from the same spectral energy distribution (SED) models are at the level of 3 × 108 M ☉ and ~5 × 1010 M ☉, respectively, with large systematic uncertainties on assumptions related to the SED model. With Hubble/WFC3 images, we also find diffuse near-IR emission about 0.5 arcsec (~3 kpc) to the southwest of HFLS3 that remains undetected in the ACS imaging data. The emission has a photometric redshift consistent with either z ~ 6 or a dusty galaxy template at z ~ 2

    The STAFF-DWP wave instrument on the DSP equatorial spacecraft: description and first results

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    The STAFF-DWP wave instrument on board the equatorial spacecraft (TC1) of the Double Star Project consists of a combination of 2&amp;nbsp;instruments which are a heritage of the Cluster mission: the Spatio-Temporal Analysis of Field Fluctuations (STAFF) experiment and the Digital Wave-Processing experiment (DWP). On DSP-TC1 STAFF consists of a three-axis search coil magnetometer, used to measure magnetic fluctuations at frequencies up to 4 kHz and a waveform unit, up to 10 Hz, plus snapshots up to 180 Hz. DWP provides several onboard analysis tools: a complex FFT to fully characterise electromagnetic waves in the frequency range 10 Hz-4 kHz, a particle correlator linked to the PEACE electron experiment, and compression of the STAFF waveform data. The complementary Cluster and TC1 orbits, together with the similarity of the instruments, permits new multi-point studies. The first results show the capabilities of the experiment, with examples in the different regions of the magnetosphere-solar wind system that have been encountered by DSP-TC1 at the beginning of its operational phase. An overview of the different kinds of electromagnetic waves observed on the dayside from perigee to apogee is given, including the different whistler mode waves (hiss, chorus, lion roars) and broad-band ULF emissions. The polarisation and propagation characteristics of intense waves in the vicinity of a bow shock crossing are analysed using the dedicated PRASSADCO tool, giving results compatible with previous studies: the broad-band ULF waves consist of a superimposition of different wave modes, whereas the magnetosheath lion roars are right-handed and propagate close to the magnetic field. An example of a combined Cluster DSP-TC1 magnetopause crossing is given. This first case study shows that the ULF wave power intensity is higher at low latitude (DSP) than at high latitude (Cluster). On the nightside in the tail, a first wave event comparison - in a rather quiet time interval - is shown. It opens the doors to future studies, such as event timing during substorms, to possibly determine their onset location

    Social movements, the European crisis, and EU political opportunities

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    Social movements in the wake of the financial crisis have shifted from the counter-summits and world social forums of the global justice movement to the camps of the anti-austerity mobilizations, and from a clear focus on building ‘another Europe’ to more domestically embedded issues. Among other reasons, this turn away from the EU can be linked to contracting political opportunities for social justice movements at the European level. This article addresses the closure of opportunities at the EU level for the work of social movement groups campaigning on specific EU policies. We reflect on the complexity of the EU’s political opportunity structure prior to the financial crisis, before examining changes to the EU’s architecture effected through responses to the crises and outlining arguments on how EU level opportunities around socio-economic issues in particular have shrunk as a result. We then show how the perception of other political opportunities at the EU level is affected by the austerity response by drawing on campaigns that sought to exploit new opportunities included in the Lisbon Treaty and designed to increase citizens’ input. Opportunities introduced by changes made in the Lisbon Treaty are perceived through the prism of contracted opportunities flowing from power shifts caused by the response to the financial crisis

    Human and Organizational Issues for Resilient Communications

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    Human and organizational issues are able to create both vulnerabilities and resilience to threats. In this chapter, we investigate human and organizational factors, conducted through ethnographic studies of operators and sets of interviews with staff responsible for security, reliability and quality in two different organizations, which own and operate utility networks. Ethnography is a qualitative orientation to research that emphasizes the detailed observation and interview of people in naturally occurring settings. Our findings indicate that 'human error' forms the biggest threat to cyber-security and that there is a need for Security Operational Centres to document all cyber-security accidents. Also, we conclude that it will always be insufficient to assess mental security models in terms of their technical correctness, as it is sometimes more important to know how well they represent prevailing social issues and requirements. As a practical recommendation from this work, we suggest that utility organizations engage in penetration testing and perhaps other forms of vulnerability analysis, not only to discover specific vulnerabilities but also to learn more about the mental models they use

    “A few sparks of inspiration”?: Analysing the outcomes of European Union cultural policy coordination

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    This article examines the outcomes of cultural policy coordination in the European Union using a case study of one policy priority in the 2011–2014 Work Plan for Culture. The Open Method of Coordination brings Member States together to exchange and cooperate on key policy priorities. Drawing on interviews with key actors as well as participant observation material, the article demonstrates the limited influence of the culture OMC on domestic policy, showing that domestic usage tends to be on the scale of individuals and organisations rather than Member State-wide. The article finishes by contextualising the outcomes, highlighting the constraints and challenges of intergovernmental coordination in fields where the EU holds a supporting competence

    Prognostic value of galectin-3, a novel marker of fibrosis, in patients with chronic heart failure: data from the DEAL-HF study

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    Biomarkers are increasingly being used in the management of patients with chronic heart failure (HF). Galectin-3 is a recently developed biomarker associated with fibrosis and inflammation, and it may play a role in cardiac remodeling in HF. We determined its prognostic value in patients with chronic HF. Patients with chronic HF (New York Heart Association functional class III or IV) who participated in the Deventer-Alkmaar heart failure study were studied. Galectin-3 levels were determined at baseline using a novel optimized enzyme-linked immunosorbent assay. Univariate and multivariate analyses were used to determine the prognostic value of this biomarker. We studied 232 patients; their mean age was 71 +/- A 10 years, 72% were male, and 96% were in NYHA class III. During a follow-up period of 6.5 years, 98 patients died. Galectin-3 was a significant predictor of mortality risk after adjustment for age and sex, and severity of HF and renal dysfunction, as assessed by NT-proBNP and estimated glomerular filtration rate, respectively (hazard ratio per standard deviation 1.24, 95% CI 1.03-1.50, P = 0.026). Plasma galectin-3 is a novel prognostic marker in patients with chronic HF. Its prognostic value is independent of severity of HF, as assessed by NT-proBNP levels, and it may potentially be used in the management of such patients
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