4,536 research outputs found

    Vehicle Motions as Inferred from Radio-signal- Strength Records

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    Considerable data on various parameters of a satellite and its launching vehicle can be obtained from the received-signal-strength records at the various satellite receiver stations. The doppler shifts of the satellite can be used to determine the orbital characteristics quite accurately. (Ref. 1 discusses the rapid determination of these parameters.) Information concerning the velocity increment and direction of each stage can be obtained if doppler data are received by several stations during the high-speed staging. The variations in signal strength during launch can be used to find the spin rate of the satellite before, during, and after staging, and to find variations in attitude, including precession, during launch. With spin and precession frequencies available, any changes in the ratios of moments of inertia can be determined. In this paper the launchings of the Explorer satellites will be used as a basis for the generalized conclusions concerning utilization of radio-signal-strength records. The discussion includes a description of the Explorer launching system

    The role of feedback in shaping the structure of the interstellar medium

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    We present an analysis of the role of feedback in shaping the neutral hydrogen (H I) content of simulated disc galaxies. For our analysis, we have used two realizations of two separate Milky Way-like (similar to L star) discs - one employing a conservative feedback scheme (McMaster Unbiased Galaxy Survey), the other significantly more energetic [Making Galaxies In a Cosmological Context (MaGICC)]. To quantify the impact of these schemes, we generate zeroth moment (surface density) maps of the inferred H I distribution; construct power spectra associated with the underlying structure of the simulated cold interstellar medium, in addition to their radial surface density and velocity dispersion profiles. Our results are compared with a parallel, self-consistent, analysis of empirical data from The H I Nearby Galaxy Survey (THINGS). Single power-law fits (P proportional to k(gamma)) to the power spectra of the stronger feedback (MaGICC) runs (over spatial scales corresponding to similar to 0.5 to similar to 20 kpc) result in slopes consistent with those seen in the THINGS sample (gamma similar to -2.5). The weaker feedback (MUGS) runs exhibit shallower power-law slopes (gamma similar to -1.2). The power spectra of the MaGICC simulations are more consistent though with a two-component fit, with a flatter distribution of power on larger scales (i.e. gamma similar to -1.4 for scales in excess of similar to 2 kpc) and a steeper slope on scales below similar to 1 kpc (gamma similar to -5), qualitatively consistent with empirical claims, as well as our earlier work on dwarf discs. The radial H I surface density profiles of the MaGICC discs show a clear exponential behaviour, while those of the MUGS suite are essentially flat; both behaviours are encountered in nature, although the THINGS sample is more consistent with our stronger (MaGICC) feedback runs

    Experiences and perceptions of Spring Lane Sure Start Children's Centre

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    Spring Lane Sure Start Children’s Centre was designated in September 2007, and ‘officially opened’ in February 2009. The Centre is housed in refurbished premises within a nursery/school complex in the heart of Northampton and offers diverse health, childcare, early education and support services delivered by a multi-professional team. These services and activities are available to children aged 0-5 years old, and their parents/carers, residing within a catchment area comprising eight ‘Super Output Areas’ in the Castle and St. James ward of Northampton. In April 2009, the Centre for Children and Youth (CCY) – a research centre based at The University of Northampton – was commissioned by Spring Lane Sure Start Children’s Centre to collate and gather evaluative data regarding experiences and perceptions of the Children’s Centre during its first year of activitie

    Constraining sub-grid physics with high-redshift spatially-resolved metallicity distributions

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    Aims. We examine the role of energy feedback in shaping the distribution of metals within cosmological hydrodynamical simulations of L* disc galaxies. While negative abundance gradients today provide a boundary condition for galaxy evolution models, in support of inside-out disc growth, empirical evidence as to whether abundance gradients steepen or flatten with time remains highly contradictory. Methods. We made use of a suite of L* discs, realised with and without "enhanced" feedback. All the simulations were produced using the smoothed particle hydrodynamics code Gasoline, and their in situ gas-phase metallicity gradients traced from redshift z similar to 2 to the present-day. Present-day age-metallicity relations and metallicity distribution functions were derived for each system. Results. The "enhanced" feedback models, which have been shown to be in agreement with a broad range of empirical scaling relations, distribute energy and re-cycled ISM material over large scales and predict the existence of relatively "flat" and temporally invariant abundance gradients. Enhanced feedback schemes reduce significantly the scatter in the local stellar age-metallicity relation and, especially, the [O/Fe]-[Fe/H] relation. The local [O/Fe] distribution functions for our L* discs show clear bimodality, with peaks at [O/Fe] = -0.05 and +0.05 (for stars with [Fe/H] > -1), consistent with our earlier work on dwarf discs. Conclusions. Our results with "enhanced" feedback are inconsistent with our earlier generation of simulations realised with "conservative" feedback. We conclude that spatially-resolved metallicity distributions, particularly at high-redshift, offer a unique and under-utilised constraint on the uncertain nature of stellar feedback processes

    Macrophage activation syndrome triggered by coeliac disease: a unique case report

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    Background: Macrophage activation syndrome is described as a “clinical syndrome of hyperinflammation resulting in an uncontrolled and ineffective immune response” in the context of an autoinflammatory or rheumatic disease. Current associations of macrophage activation syndrome with autoimmune disease most notably include a host of rheumatological conditions and inflammatory bowel disease. Epidemiological studies have shown that macrophage activation syndrome is precipitated by autoimmune disease more commonly than previously thought. Diagnosing the precipitating factor is essential for effective treatment and prognosis. Case presentation: We report a case of a six year old girl with coeliac disease diagnosed after two episodes of secondary haemophagocytic lymphohistiocytosis. Her condition only responded to treatment once the patient was placed on a gluten free diet. Further immunological testing confirmed anti-transglutaminase and anti-endomysial antibodies, however histological biopsy was deemed inappropriate due to the severity of her condition. She has remained stable with no further episodes of macrophage activation syndrome since commencing a gluten free diet. Conclusion: This case report is the first literature that links macrophage activation syndrome to coeliac disease and highlights the challenge of diagnosing coeliac disease with unusual features such as associated prolonged fever. Clinicians should have a low threshold for screening children with other autoimmune diseases for coeliac disease
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