323 research outputs found
Newtonian limit of the singular f(R) gravity in the Palatini formalism
Recently D. Vollick [Phys. Rev. D68, 063510 (2003)] has shown that the
inclusion of the 1/R curvature terms in the gravitational action and the use of
the Palatini formalism offer an alternative explanation for cosmological
acceleration. In this work we show not only that this model of Vollick does not
have a good Newtonian limit, but also that any f(R) theory with a pole of order
n in R=0 and its second derivative respect to R evaluated at Ro is not zero,
where Ro is the scalar curvature of background, does not have a good Newtonian
limit.Comment: 9 page
Stellar explosion in the weak field approximation of the Brans-Dicke theory
We treat a very crude model of an exploding star, in the weak field
approximation of the Brans-Dicke theory, in a scenario that resembles some
characteristics data of a Type Ia Supernova. The most noticeable feature, in
the electromagnetic component, is the relationship between the absolute
magnitude at maximum brightness of the star and the decline rate in one
magnitude from that maximum. This characteristic has become one of the most
accurate method to measure luminosity distances to objects at cosmological
distances. An interesting result is that the active mass associated with the
scalar field is totally radiated to infinity, representing a mass loss in the
ratio of the "tensor" component to the scalar component of 1 to ( is the Brans-Dicke parameter), in agreement with a general result
of Hawking. Then, this model shows explicitly, in a dynamical case, the
mechanism of radiation of scalar field, which is necessary to understand the
Hawking result.Comment: 11 pages, no figures. Published in Class. Quantum Gravity V22 (2005
TTF-1/p63-positive poorly differentiated NSCLC: A histogenetic hypothesis from the basal reserve cell of the terminal respiratory unit
TTF-1 is expressed in the alveolar epithelium and in the basal cells of distal terminal bronchioles. It is considered the most sensitive and specific marker to define the adenocarcinoma arising from the terminal respiratory unit (TRU). TTF-1, CK7, CK5/6, p63 and p40 are useful for typifying the majority of non-small-cell lung cancers, with TTF and CK7 being typically expressed in adenocarcinomas and the latter three being expressed in squamous cell carcinoma. As tumors with coexpression of both TTF-1 and p63 in the same cells are rare, we describe different cases that coexpress them, suggesting a histogenetic hypothesis of their origin. We report 10 cases of poorly differentiated non-small-cell lung carcinoma (PD-NSCLC). Immunohistochemistry was performed by using TTF-1, p63, p40 (âNp63), CK5/6 and CK7. EGFR and BRAF gene mutational analysis was performed by using real-time PCR. All the cases showed coexpression of p63 and TTF-1. Six of them showing CK7+ and CK5/6â immunostaining were diagnosed as âTTF-1+ p63+ adenocarcinomaâ. The other cases of PD-NSCLC, despite the positivity for CK5/6, were diagnosed as âadenocarcinoma, solid variantâ, in keeping with the presence of TTF-1 expression and p40 negativity. A âwild typeâ genotype of EGFR was evidenced in all cases. TTF1 stained positively the alveolar epithelium and the basal reserve cells of TRU, with the latter also being positive for p63. The coexpression of p63 and TTF-1 could suggest the origin from the basal reserve cells of TRU and represent the capability to differentiate towards different histogenetic lines. More aggressive clinical and morphological features could characterize these âbasal-type tumorsâ like those in the better known âbasal-likeâ cancer of the breast
Equilibrium hydrostatic equation and Newtonian limit of the singular f(R) gravity
We derive the equilibrium hydrostatic equation of a spherical star for any
gravitational Lagrangian density of the form . The Palatini
variational principle for the Helmholtz Lagrangian in the Einstein gauge is
used to obtain the field equations in this gauge. The equilibrium hydrostatic
equation is obtained and is used to study the Newtonian limit for
. The same procedure is carried out for the more
generally case giving a good
Newtonian limit.Comment: Revised version, to appear in Classical and Quantum Gravity
The Grass is Always Greener: Surviving Mergers and Acquisitions, No Matter Your Side of the Fence.
The Information-Seeking Behaviors of Pediatricians regarding Treatment Benefits and Harms at Lehigh Valley Health Network (LVHN).
Vino e Ambiente: sostenibilitĂ e qualitĂ primaria nel sottobacino Iudeo-Bucari (TP).
In questa raccolta di scritti, vengono riportati i risultati dellâattivitĂ di ricerca realizzata con la collaborazione della cantina UVAM e dellâIstituto Regionale Vino e Olio di Sicili
The Information Seeking Behaviors of Providers Regarding Benefits/Harms of Treatments at Lehigh Valley Health Network-A Pilot Study
HEREDITARY BREAST AND OVARIAN CANCER SYNDROME: FREQUENCY AND DISTRIBUTION OF BRCA1/2 PATHOGENIC VARIANTS IN SICILIAN POPULATION
- âŠ