162,925 research outputs found
Geometry, EFE's and Foundations for Brane Cosmology
I argue that GR Cauchy and Initial Value Problem mathematics is a valuable
source of ideas for braneworlds based on higher-dimensional Einstein field
equations.Comment: 2 pages, to appear in Proceedings of Rio de Janeiro 2003 Marcel
Grossmann Meetin
Relational particle models as toy models for quantum gravity and quantum cosmology
It is argued that substantial portions of both Newtonian particle mechanics
and general relativity can be viewed as relational (rather than absolute)
theories. I furthermore use the relational particle models as toy models to
investigate the problem of time in closed-universe canonical quantum general
relativity. I consider thus in particular the internal time, semiclassical and
records tentative resolutions of the problem of time.Comment: Talk at Einstein centenary conference, Paris. Minor update with
reference
Hydraulic expansion process shapes large metal sheets
Process imparts dome shape to titanium sheets and is applicable to shaping other metals. Method is of interest to automobile and aircraft body manufacturers
Criminal Minded? : Mixtape DJs, The Piracy Paradox, and Lessons for the Recording Industry
For at least the past three years, leading American fashion designers have lobbied for passage of copyright-like protection for the design aspects of their apparel creations. For at least as long, the recorded music industry has been engaged in an aggressive campaign to enforce its copyrights in recorded music against a number of technology-enabled and/or culturally sympathetic alleged infringers, including twelve year-olds and grandmothers. Although the record labels already have protection under the copyright law while the fashion houses seek it, they have at least one thing in common: some portion of the piracy that they seek to eradicate is more valuable to them than they publicly let on. In their recent article The Piracy Paradox: Innovation and Intellectual Property in Fashion Design, Kal Raustiala and Chris Sprigman explore the low-IP equilibrium of the fashion design industry, as well as the unexpected value created by a low-protection regime.
One might ask whether there is anything wrong with chilling an unlawful activity such as large-scale copyright infringement. The article argues that there is something wrong with such a result, but that the owners of the copyright in the recordings either fail to appreciate the problem or fail to account for the problem in executing their enforcement strategy. Hip-hop mixtape DJs are engaged in productive infringement â infringing activity or improper appropriation that adds value to the infringed asset, rather than leading to losses for the copyright owner. Dealing with such infringement requires an approach different from typical recording industry tactics. This article argues that, in order to preserve and enhance the value of their own assets, the record labels should practice strategic forbearance
Risky drinking patterns are being continued into pregnancy: a prospective cohort study
Background: Risky patterns of alcohol use prior to pregnancy increase the risk of alcohol-exposed pregnancies and subsequent adverse outcomes. It is important to understand how consumption changes once women become pregnant.
Objective: The aim of this study was to describe the characteristics of women that partake in risky drinking patterns before pregnancy and to examine how these patterns change once they become pregnant.
Methods: A sample of 1577 women from the 1973â78 cohort of the Australian Longitudinal Study on Womenâs Health were included if they first reported being pregnant in 2000, 2003, 2006, 2009 and reported risky drinking patterns prior to that pregnancy. Multinomial logistic regression was used to determine which risky drinking patterns were most likely to
continue into pregnancy.
Results: When reporting risky drinking patterns prior to pregnancy only 6% of women reported weekly drinking only,
whereas 46% reported binge drinking only and 48% reported both. Women in both binge categories were more likely to
have experienced financial stress, not been partnered, smoked, used drugs, been nulliparous, experienced a violent
relationship, and were less educated. Most women (46%) continued these risky drinking patterns into pregnancy, with 40% reducing these behaviors, and 14% completely ceasing alcohol consumption. Once pregnant, women who binged only prior to pregnancy were more likely to continue (55%) rather than reduce drinking (29%). Of the combined drinking group 61% continued to binge and 47% continued weekly drinking. Compared with the combined drinking group, binge only drinkers prior to pregnancy were less likely to reduce rather than continue their drinking once pregnant (OR = 0.37, 95% CI = 0.29, 0.47).
Conclusions: Over a third of women continued risky drinking into pregnancy, especially binge drinking, suggesting a need
to address alcohol consumption prior to pregnancy.
Alexis J. Hure, Peta M. Forder, Jennifer Powers, Frances J. Kay-Lambkin, Deborah J. Loxto
Quantum Cosmological Relational Model of Shape and Scale in 1-d
Relational particle models are useful toy models for quantum cosmology and
the problem of time in quantum general relativity. This paper shows how to
extend existing work on concrete examples of relational particle models in 1-d
to include a notion of scale. This is useful as regards forming a tight analogy
with quantum cosmology and the emergent semiclassical time and hidden time
approaches to the problem of time. This paper shows furthermore that the
correspondence between relational particle models and classical and quantum
cosmology can be strengthened using judicious choices of the mechanical
potential. This gives relational particle mechanics models with analogues of
spatial curvature, cosmological constant, dust and radiation terms. A number of
these models are then tractable at the quantum level. These models can be used
to study important issues 1) in canonical quantum gravity: the problem of time,
the semiclassical approach to it and timeless approaches to it (such as the
naive Schrodinger interpretation and records theory). 2) In quantum cosmology,
such as in the investigation of uniform states, robustness, and the qualitative
understanding of the origin of structure formation.Comment: References and some more motivation adde
- âŚ