572 research outputs found
Pronouncing French Names in New Orleans
This article, based on 984 interviews with bearers of French names in the city of New Orleans, investigates the use of the notion of pronunciation as a device by which speakers manage their talk. The investigation proceeded primarily by eliciting ways in which people employ devices for talking about talk in everyday communicative interactions, as a means to manage various types of communicational phenomena and to deal with communication difficulties emerging from a clash of phonetic traditions. The result is a definition of pronunciation in terms which are used by a majority of speakers. An appendix gives a list of names, with comments by their bearers concerning ways in which those bearers would attempt to convey to mispronouncers the correct pronunciation of their names
Cosmological Scaling Solutions with Tachyon:Modified Gravity Model
Modifying the Einstein's gravity at large distance scales is one of the
interesting proposals to explain the late time acceleration of the universe. In
this paper, we analyse scaling solutions in modified gravity models where the
universe is sourced by a background matter fluid together with a tachyon type
scalar field. We describe a general prescription to calculate the scaling
potential in such models. Later on, we consider specific examples of
modifications and apply our method to calculate the scaling potential and the
scale factor. Our method can be applied to any modified gravity model, in
presence of a tachyon field.Comment: 6 pages, latex style, modified version, two new figures included, new
refernces added, Accepted for publication in Physics Letters
Quantum singularities in a model of f(R) Gravity
The formation of a naked singularity in a model of f(R) gravity having as
source a linear electromagnetic field is considered in view of quantum
mechanics. Quantum test fields obeying the Klein-Gordon, Dirac and Maxwell
equations are used to probe the classical timelike naked singularity developed
at r=0. We prove that the spatial derivative operator of the fields fails to be
essentially self-adjoint. As a result, the classical timelike naked singularity
remains quantum mechanically singular when it is probed with quantum fields
having different spin structures.Comment: 12 pages, final version. Accepted for publication in EPJ
Long-Term Effects of Neonatal Exposure to Hydroxylated Polychlorinated Biphenyls in the BALB/cCrgl Mouse
The neonatal mouse model has been a valuable tool in determining the long-term effects of early exposure to estrogenic agents in mammals. Using this model, we compared the effects of 2′,4′,6′-trichloro-4-biphenylol (OH-PCB-30) and 2′,3′,4′,5′-tetrachloro-4-biphenylol (OH-PCB-61) as prototype estrogenic hydroxylated PCBs (OH-PCBs) because they are reported to exhibit relatively high estrogenic activity both in vivo and in vitro. The purpose of this study was to examine the relationship between estrogenicity and carcinogenicity of OH-PCB congeners. The OH-PCBs were tested individually and in combination to determine whether effects of combined OH-PCBs differed from those of these OH-PCBs alone. We evaluated the long-term effects of neonatal exposure to OH-PCBs with treatment doses that were based on the reported binding affinity of specific OH-PCB congeners to estrogen receptor α. BALB/cCrgl female mice were treated within 16 hr after birth by subcutaneous injections every 24 hr, for 5 days. The mice treated with OH-PCB-30 (200 μg/day) or 17β-estradiol (5 μg/day) showed similar increased incidences of cervicovaginal (CV) tract carcinomas (43% and 47%, respectively). In addition, when mice were treated with OH-PCBs as a mixture, a change in the type of CV tract tumor was observed, shifting from predominantly squamous cell carcinomas to adenosquamous cell carcinoma. From our results, we conclude that the individual OH-PCBs tested were estrogenic and tumorigenic in mice when exposed during development of the reproductive tract. These data support the hypothesis that mixtures may act differently and unexpectedly than do individual compounds
Cosmological models in scalar tensor theories of gravity and observations: a class of general solutions
We consider cosmological models in scalar tensor theories of gravity that
describe an accelerating universe, and we study a family of inverse power law
potentials, for which exact solutions of the Einstein equations are known. We
also compare theoretical predictions of our models with observations. For this
we use the following data: the publicly available catalogs of type Ia
supernovae and high redshift Gamma Ray Bursts, the parameters of large scale
structure determined by the 2-degree Field Galaxy Redshift Survey (2dFGRS), and
measurements of cosmological distances based on the Sunyaev-Zel'dovich effect,
among others.Comment: 26 pages,23 figures, accepted for publication in A&
Modified Gravity and Cosmology
In this review we present a thoroughly comprehensive survey of recent work on
modified theories of gravity and their cosmological consequences. Amongst other
things, we cover General Relativity, Scalar-Tensor, Einstein-Aether, and
Bimetric theories, as well as TeVeS, f(R), general higher-order theories,
Horava-Lifschitz gravity, Galileons, Ghost Condensates, and models of extra
dimensions including Kaluza-Klein, Randall-Sundrum, DGP, and higher
co-dimension braneworlds. We also review attempts to construct a Parameterised
Post-Friedmannian formalism, that can be used to constrain deviations from
General Relativity in cosmology, and that is suitable for comparison with data
on the largest scales. These subjects have been intensively studied over the
past decade, largely motivated by rapid progress in the field of observational
cosmology that now allows, for the first time, precision tests of fundamental
physics on the scale of the observable Universe. The purpose of this review is
to provide a reference tool for researchers and students in cosmology and
gravitational physics, as well as a self-contained, comprehensive and
up-to-date introduction to the subject as a whole.Comment: 312 pages, 15 figure
- …