417 research outputs found

    The static spherically symmetric body in relativistic elasticity

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    In this paper is discussed a class of static spherically symmetric solutions of the general relativistic elasticity equations. The main point of discussion is the comparison of two matter models given in terms of their stored energy functionals, i.e., the rule which gives the amount of energy stored in the system when it is deformed. Both functionals mimic (and for small deformations approximate) the classical Kirchhoff-St.Venant materials but differ in the strain variable used. We discuss the behavior of the systems for large deformations.Comment: 19 pages, 8 figure

    Observable implications of geometrical and dynamical aspects of freeze-out in heavy ion collisions

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    Using an analytical parameterization of hadronic freeze-out in relativistic heavy ion collisions, we present a detailed study of the connections between features of the freeze-out configuration and physical observables. We focus especially on anisotropic freeze-out configurations (expected in general for collisions at finite impact parameter), azimuthally-sensitive HBT interferometry, and final-state interactions between non-identical particles. Model calculations are compared with data taken in the first year of running at RHIC; while not perfect, good agreement is found, raising the hope that a consistent understanding of the full freeze-out scenario at RHIC is possible, an important first step towards understanding the physics of the system prior to freeze-out.Comment: 36 pages, 56 figures, 2 tables; version accepted for publication in PRC: some figures, references and discussion added; now also discusses classical versus quantum statistic

    Targeting dsRNA-specific single-chain Fv antibody fragments to different cellular locations in Nicotiana tabacum L.

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    Expression of antibodies or antibody fragments in plants is a useful tool for producing active antibody derivatives for diagnostic or pharmaceutical purposes as well as for immunomodulation. We investigated the effect of cellular expression site on the stability and yield of double-stranded RNA (dsRNA)-specific single-chain Fv-fragments (scFv) in transgenic tobacco. Two antibodies (J2 and P6) belonging to the V23(J558) heavy chain variable gene family but differing in the light chain variable domain were used. scFvs were targeted to the cytoplasm – with or without anchoring them in the plasma membrane –, into the endoplasmic reticulum (ER) and to the apoplast. Although high mRNA concentrations were detected in all cases, scFv proteins accumulated only when scFvs were made ER-resident by appropriate signal sequences. When the ER retention signal was removed to allow scFv-secretion to the apoplast, no scFv-proteins were detected. Despite the strong homology of the VH-sequences of J2 and P6 antibodies, only P6 provided a stable scFv scaffold for intracytoplasmic expression. J2-scFv could not be stabilised neither by adding a C-terminal stabilisation signal nor by anchoring the protein at the cytoplasmic side of the plasma membrane (PM). It was found that dsRNA-specific J2-scFvs are active in vivo and enhance Potato Virus Y induced symptoms in infected tobacco. This is the first report describing the expression and biological effect of RNA-specific antibodies in plants

    Irreducible decomposition of Gaussian distributions and the spectrum of black-body radiation

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    It is shown that the energy of a mode of a classical chaotic field, following the continuous exponential distribution as a classical random variable, can be uniquely decomposed into a sum of its fractional part and of its integer part. The integer part is a discrete random variable (we call it Planck variable) whose distribution is just the Bose distribution yielding the Planck law of black-body radiation. The fractional part is the dark part (we call is dark variable) with a continuous distribution, which is, of course, not observed in the experiments. It is proved that the Bose distribution is infinitely divisible, and the irreducible decomposition of it is given. The Planck variable can be decomposed into an infinite sum of independent binary random variables representing the binary photons (more accurately photo-molecules or photo-multiplets) of energies 2^s*h*nu with s=0,1,2... . These binary photons follow the Fermi statistics. Consequently, the black-body radiation can be viewed as a mixture of statistically and thermodynamically independent fermion gases consisting of binary photons. The binary photons give a natural tool for the dyadic expansion of arbitrary (but not coherent) ordinary photon excitations. It is shown that the binary photons have wave-particle fluctuations of fermions. These fluctuations combine to give the wave-particle fluctuations of the original bosonic photons expressed by the Einstein fluctuation formula.Comment: 29 page

    Idylls of socialism : the Sarajevo Documentary School and the problem of the Bosnian sub-proletariat

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    This historical overview of the Sarajevo Documentary School considers the films, in the light of their recent re-emergence, as indicative of both the legacy of socialist realism (even in the context of Yugoslav media) and attempted social engineering in the Bosnia of the 1960s and 1970s. The argument is made that the documentaries, despite their questionable aesthetic status (in respect of cinma-vrit and ethnography) and problematic ideological strategies and attempted interventions, document a history and offer insights that counter the prevailing revisionist trends in the presentation of Eastern and Central European history

    Crime or social harm? A dialectical perspective

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    This paper proposes to examine some of the core philosophical issues to have arisen out of the recent calls to move "beyond criminology". It will be claimed that the dismissal of crime as a "fictive event" is premature, as crime does indeed have an "ontological reality". Nevertheless, it will be asserted that the relation between harm and crime is contingent rather than necessary. Accordingly, this paper will argue that there is merit to the claim that we should unify research on social harm through the creation of a new field, a step which would have the added benefit of constructing an alternative venue for crimes of the powerful scholars who wish to explore the destructive practices of states and corporations unconstrained. This paper, therefore, will also offer a dialectical definition of social harm based upon classical Marxist strains of ontological thought

    History and Class Consciousness 2.0: Georg Lukács in the age of digital capitalism and big data

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    This paper discusses the relevance of Georg Lukács’ 1923 book History and Class Consciousness in the context of digital capitalism. It does so by analysing how Lukács’ concepts of the dialectic of subject and object, ideology, reification, reified consciousness matter today in the context of big data and digital capitalism. The essay shows that History and Class Consciousness’ critique of reification, ideology, and reified consciousness remains highly topical in the age of digital capitalism and big data. Lukács’ analysis allows us to critically analyse how social media, big data, and various other Internet technologies are used as tools of reification. At the same time, Lukács reminds us that only human praxis can establish alternatives

    Meat production and maintaining biodiversity: Grazing by traditional breeds and crossbred beef cattle in marshes and grasslands

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    Questions: Sustainable rangeland utilization considering traditions and economic reasons is compulsory for harmonising the needs of the agricultural and nature conservation sectors. For proper rangeland management it is crucial to compare the grazing effects of traditional breeds and crossbred animals of the same species that might have different effects on the rangelands. To fill this knowledge gap, in a grazing experiment, we investigated the effect of cattle breeds on the vegetation to test the effects on nature conservation value and agricultural production value. We hypothesized that the effects of cattle grazing on habitat conservation values and forage quality depend on the grazing breed, because breeds differ in selectivity, body size and trampling effect. Location: Marshes and alkaline wet grasslands in Hortobágy National Park, Hungary. Methods: We recorded the percentage cover of vascular plants in three consecutive years in a total of 60 plots in 12 areas grazed by traditional (0.61 AU/ha) and largesized crossbred beef cattle (0.68 AU/ha). Results: We found that the effect of cattle breed on the habitat conservation values and forage quality is dependent on the habitat type. The traditional breed maintained a significantly higher species number and Shannon diversity in marshes than the crossbred beef cattle. Grazing of crossbred cattle led to decreasing moisture indicator values in marsh habitats. Conclusions: Our findings revealed that traditional breeds should be prioritized in the management of wet alkaline grasslands and marshes. Crossbred beef cattle might be a substitute but only in case traditional breeds are not available for the management of alkaline wet grasslands. In marshes, however, we recommend prioritizing the traditional breeds as they maintain higher diversity compared to crossbred beef cattle

    Stringy Robinson-Trautman Solutions

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    A class of solutions of the low energy string theory in four dimensions is studied. This class admits a geodesic, shear-free null congruence which is non-twisting but in general diverging and the corresponding solutions in Einstein's theory form the Robinson-Trautman family together with a subset of the Kundt's class. The Robinson-Trautman conditions are found to be frame invariant in string theory. The Lorentz Chern-Simons three form of the stringy Robinson-Trautman solutions is shown to be always closed. The stringy generalizations of the vacuum Robinson-Trautman equation are obtained and three subclasses of solutions are identified. One of these subclasses exists, among all the dilatonic theories, only in Einstein's theory and in string theory. Several known solutions including the dilatonic black holes, the pp- waves, the stringy C-metric and certain solutions which correspond to exact conformal field theories are shown to be particular members of the stringy Robinson-Trautman family. Some new solutions which are static or asymptotically flat and radiating are also presented. The radiating solutions have a positive Bondi mass. One of these radiating solutions has the property that it settles down smoothly to a black hole state at late retarded times.Comment: Latex, 30 Pages, 1 Figure; to appear in Phys. Rev.
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