3,141 research outputs found

    Exploring hidden narratives: Conscript graffiti at the former military base of Kummersdorf

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    This article explores the cultural significance and interpretative potential of graffiti left by Soviet conscripts at Kummersdorf, a former military base in the German federal state of Brandenburg. The graffiti is framed as war art and its typology, distribution and content is studied in detail. In this way opportunities for further research are highlighted, as well as the potential for the graffiti to contribute to interpretative and conservation strategies. We demonstrate how the graffiti embodies multi-level interpretative narratives which can help to reveal hidden aspects of Soviet conscript life and cultural practices whilst alluding to global events and Soviet and Russian military policy. More generally, the article aims to promote the potential of graffiti and other forms of what is traditionally considered vandalism to contribute to the cultural significance and interpretation of heritage sites

    Solar electric propulsion for Mars transport vehicles

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    Solar electric propulsion (SEP) is an alternative to chemical and nuclear powered propulsion systems for both piloted and unpiloted Mars transport vehicles. Photovoltaic solar cell and array technologies were evaluated as components of SEP power systems. Of the systems considered, the SEP power system composed of multijunction solar cells in an ENTECH domed fresnel concentrator array had the least array mass and area. Trip times to Mars optimized for minimum propellant mass were calculated. Additionally, a preliminary vehicle concept was designed

    On Languages Accepted by P/T Systems Composed of joins

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    Recently, some studies linked the computational power of abstract computing systems based on multiset rewriting to models of Petri nets and the computation power of these nets to their topology. In turn, the computational power of these abstract computing devices can be understood by just looking at their topology, that is, information flow. Here we continue this line of research introducing J languages and proving that they can be accepted by place/transition systems whose underlying net is composed only of joins. Moreover, we investigate how J languages relate to other families of formal languages. In particular, we show that every J language can be accepted by a log n space-bounded non-deterministic Turing machine with a one-way read-only input. We also show that every J language has a semilinear Parikh map and that J languages and context-free languages (CFLs) are incomparable

    The Intrinsic Absorber in QSO 2359-1241: Keck and HST Observations

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    We present detailed analyses of the absorption spectrum seen in QSO 2359-1241 (NVSS J235953-124148). Keck HIRES data reveal absorption from twenty transitions arising from: He I, Mg I, Mg II, Ca II, and Fe II. HST data show broad absorption lines (BALs) from Al III 1857, C IV 1549, Si IV 1397, and N V 1240. Absorption from excited Fe II states constrains the temperature of the absorber to 2000K < T < 10,000K and puts a lower limit of 10^5 cm^{-3} on the electron number density. Saturation diagnostics show that the real column densities of He I and Fe II can be determined, allowing to derive meaningful constraints on the ionization equilibrium and abundances in the flow. The ionization parameter is constrained by the iron, helium and magnesium data to -3.0 < log(U) < -2.5 and the observed column densities can be reproduced without assuming departure from solar abundances. From comparison of the He I and Fe II absorption features we infer that the outflow seen in QSO 2359-1241 is not shielded by a hydrogen ionization front and therefore that the existence of low-ionization species in the outflow (e.g., Mg II, Al III, Fe II) does not necessitate the existence of such a front. We find that the velocity width of the absorption systematically increases as a function of ionization and to a lesser extent with abundance. Complementary analyses of the radio and polarization properties of the object are discussed in a companion paper (Brotherton et al. 2000).Comment: 30 pages, 9 figures, in press with the Ap

    Effective quantum gravity observables and locally covariant QFT

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    Perturbative algebraic quantum field theory (pAQFT) is a mathematically rigorous framework that allows to construct models of quantum field theories on a general class of Lorentzian manifolds. Recently this idea has been applied also to perturbative quantum gravity, treated as an effective theory. The difficulty was to find the right notion of observables that would in an appropriate sense be diffeomorphism invariant. In this article I will outline a general framework that allows to quantize theories with local symmetries (this includes infinitesimal diffeomorphism transformations) with the use of the BV (Batalin-Vilkovisky) formalism. This approach has been successfully applied to effective quantum gravity in a recent paper by R. Brunetti, K. Fredenhagen and myself. In the same paper we also proved perturbative background independence of the quantized theory, which is going to be discussed in the present work as well.Comment: 16 pages, based on a plenary talk given at the 14th Marcel Grossmann Meeting in Rome (July 2015

    Prognostic impact of systemic inflammatory diseases in elderly patients with congestive heart failure

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    Background and aims: Inflammation is part of the pathophysiology of congestive heart failure (CHF). However, little is known about the impact of the presence of systemic inflammatory disease (SID), defined as inflammatory syndrome with constitutional symptoms and involvement of at least two organs as co-morbidity on the clinical course and prognosis of patients with CHF. Methods and results: This is an analysis of all 622 patients included in TIME-CHF. After an 18 months follow-up, outcomes of patients with and without SID were compared. Primary endpoint was all-cause hospitalization free survival. Secondary endpoints were overall survival and CHF hospitalization free survival. At baseline, 38 patients had history of SID (6.1%). These patients had higher N-terminal pro brain natriuretic peptide and worse renal function than patients without SID. SID was a risk factor for adverse outcome [primary endpoint: hazard ratio (HR) = 1.73 (95% confidence interval: 1.18-2.55, P = 0.005); survival: HR = 2.60 (1.49-4.55, P = 0.001); CHF hospitalization free survival: HR = 2.3 (1.45-3.65, P < 0.001)]. In multivariate models, SID remained the strongest independent risk factor for survival and CHF hospitalization free survival. Conclusions: In elderly patients with CHF, SID is independently accompanied with adverse outcome. Given the increasing prevalence of SID in the elderly population, these findings are clinically important for both risk stratification and patient managemen

    Early school outcomes for extremely preterm infants with transient neurological abnormalities

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    AIM: To determine if transient neurological abnormalities (TNA) at 9 months corrected age predict cognitive, behavioral, and motor outcomes at 6 years of age in extremely preterm infants. METHOD: A cohort of 124 extremely preterm infants (mean gestational age 25.5wks; 55 males, 69 females), admitted to our unit between 2001 and 2003, were classified based on the Amiel-Tison Neurological Assessment at 9 months and 20 months corrected age as having TNA (n=17), normal neurological assessment (n=89), or neurologically abnormal assessment (n=18). The children were assessed at a mean age of 5 years 11 months (SD 4mo) on cognition, academic achievement, motor ability, and behavior. RESULTS: Compared with children with a normal neurological assessment, children with TNA had higher postnatal exposure to steroids (35% vs 9%) and lower adjusted mean scores on spatial relations (84 [standard error {SE} 5] vs 98 [SE 2]), visual matching (79 [SE 5] vs 91 [SE 2]), letter-word identification (97 [SE 4] vs 108 [SE 1]), and spelling (76 [SE 4] vs 96 [SE 2]) (all p<0.05). INTERPRETATION: Despite a normalized neurological assessment, extremely preterm children with a history TNA are at higher risk for lower cognitive and academic skills than those with normal neurological findings during their first year of school
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