1,562 research outputs found
Universe Models with Negative Bulk Viscosity
The concept of negative temperatures has occasionally been used in connection
with quantum systems. A recent example of this sort is reported in the paper of
S. Braun et al. [Science 339,52 (2013)], where an attractively interacting
ensemble of ultracold atoms is investigated experimentally and found to
correspond to a negative-temperature system since the entropy decreases with
increasing energy at the high end of the energy spectrum. As the authors
suggest, it would be of interest to investigate whether a suitable
generalization of standard cosmological theory could be helpful, in order to
elucidate the observed accelerated expansion of the universe usually explained
in terms of a positive tensile stress (negative pressure). In the present note
we take up this basic idea and investigate a generalization of the standard
viscous cosmological theory, not by admitting negative temperatures but instead
by letting the bulk viscosity take negative values. Evidently, such an approach
breaks standard thermodynamics, but may actually be regarded to lead to the
same kind of bizarre consequences as the standard approach of admitting the
equation-of-state parameter w to be less than -1. In universe models dominated
by negative viscosity we find that the fluid's entropy decreases with time, as
one would expect. Moreover, we find that the fluid transition from the
quintessence region into the phantom region (thus passing the phantom divide
w=-1) can actually be reversed. Also in generalizations of the LCDM-universe
models with a fluid having negative bulk viscosity we find that the viscosity
decreases the expansion of the universe.Comment: 7 pages latex, no figures, published electronically in Astrophys.
Space Sc
The Cosmic Causal Mass
In order to provide a better understanding of rotating universe models, and
in particular the G\"{o}del universe, we discuss the relationship between
cosmic rotation and perfect inertial dragging. In this connection, the concept
of \emph{causal mass} is defined in a cosmological context, and discussed in
relation to the cosmic inertial dragging effect. Then, we calculate the mass
inside the particle horizon of the flat CDM-model integrated along the
past light cone. The calculation shows that the Schwarzschild radius of this
mass is around three times the radius of the particle horizon. This indicates
that there is close to perfect inertial dragging in our universe. Hence, the
calculation provides an explanation for the observation that the swinging plane
of a Foucault pendulum follows the stars.Comment: 17 pages, 3 figure
Comment on "The Cosmic Time in Terms of the Redshift", by Carmeli et al
The time-redshift relation of Carmeli et al. differs from that of the
standard flat LambdaCDM model by more than 500 million years for 1 < z < 4.5.Comment: 2 pages, to appear Found. Phys. Let
FRW Universe Models in Conformally Flat Spacetime Coordinates. III: Universe models with positive spatial curvature
We deduce general expressions for the line element of universe models with
positive spatial curvature described by conformally flat spacetime coordinates.
Models with dust, radiation and vacuum energy are exhibited. Discussing the
existence of particle horizons we show that there is continual annihilation of
space, matter and energy in a dust and radiation dominated universe, and
continual creation in a LIVE domined universe when conformal time is used in
Friedmann-Robertson-Walker models with positive spatial curvature. A general
procedure is given for finding coordinates to be used in Penrose diagrams. We
also calculate the age and the redshift of some universe models using conformal
time.Comment: 22 pages, 9 figure
Legal Language and The Legal Translator
It is impossible to set up standards of translation performance and equivalence which will apply to any legal translation because the "languages of law" are as varied as the cases that reach the courts every day. Moreover, the translation of legal texts is often complicated by the lack of exact lexical equivalents in the TL's own legal system so that a transfer involves a high amount of "creative production". Obviously this production should be based on a profound extra-linguistic knowledge of both legal systems involved to avoid the pitfalls which the difference in conceptual meaning necessarily entails. Thus research into the TL's substantive law must be the first requirement in any legal translation context
World cinema beyond the periphery : developing film cultures in Bhutan, Mongolia, and Myanmar
According to UNESCO’s Universal Declaration on Cultural Diversity there exists a need in light of the “imbalances in flows and exchanges of cultural goods and services at the global level” to enable “all countries, especially developing countries and countries in transition, to establish cultural industries that are viable and competitive at a national and international level” (2001).
The dissertation explores ways in which viable cultural industries can be established in developing countries. More specifically, the focus is on the development of film industries in countries in transition. Three national film industries, examined in light of their historical development and contemporary situation, provide the empirical basis for the dissertation’s claims and arguments.
The three developing countries under investigation are Bhutan, Mongolia, and Myanmar, and in each case the study traces the historical trajectory of the relevant film industries leading to the mapping of the recent trends and tendencies. The examination of the individual cases foregrounds industrial and commercial challenges and solutions rather than the aesthetic or stylistic properties of specific films. That is, the study seeks to explore how educational practices, production modes, approaches to distribution and exhibition, and cultural policy measures have facilitated or thwarted the emergence of film industries in three developing countries in the Asian region.
The approach taken builds on the call for a more inclusive approach to the study of world cinema (Nagib 2006). Equally important is an analytical approach derived from the field of small national cinema studies, one that underscores the need to explore solutions to problems facing filmmakers in countries sharing similar developmental challenges (Hjort & Petrie 2007).
Following this conceptual perspective the study aims firstly, through its historical examination, to contribute to expanding the historiography of world cinema, where little to no attention is given to these largely unexplored national cinema cultures. Secondly, following the mapping of the contemporary situation of the institutional and organizational make-up of the film industries in question, the aim is to identify the systematic challenges and opportunities that are embedded in specific film sectors. The approach is applied with the intention of facilitating a constructive discussion that explores and compares proactive strategies. The point ultimately is to identify models that might be more generally relevant and thus transferable across national boundaries
Social Behaviour and Settlement Structure: Preliminary Results of a Distribution Analysis on Sites of the Maglemose Culture
Social Behaviour and Settlement Structure. Preliminary Results of a Distribution Analysis on Sites of the Maglemose Culture
Mammoth-hunter Camps in the Scandinavian North Sea Sector during the Late Weichselian?
Until recently, the general view of archaeologists was that southern Scandinavia was uninhabited during the last ice age, the Weichselian glaciation. It was thought that humans arriving from south would have met a wall of ice if they tried to penetrate into the area. Recent climate reconstructions and glaciological data, combined with recent faunal finds from the adjacent North Sea sector, promote the idea of a much more moderate and prosperous landscape with large, now submerged, plains accessible. Then this paper argues that large parts of the South Scandinavian North Sea sector were actually inhabitable during most of this glacial period, with extensive ice-free coastal zones even during the Last Glacial Maximum. It is difficult to believe that humans, already well-documented in the adjacent land areas, should not have known to inhabit and exploit such a rich resource zone. In addition to the paleoenvironmental data, ethnoarchaeological evidence is used to document that it was no problem for humans to kill large animals such as mammoths as some researchers have maintained. Furthermore, findings from excavations of mammoth-hunter sites, are used to argue that the large quantities of megafaunal remains fished up from the North Sea in recent years should be seriously considered as representing settlement material associated with mammoth-hunter camps dating from the second half of the Weichsel Glacial Stage. The central question is whether these North Sea faunal remains represent sites similar to the mammoth-hunter camps known from other parts of Europe and from Siberia? If that is the case, the Cultural Heritage management is confronted with a hitherto unrecognised problem
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