10,345 research outputs found
Black holes in the Brans-Dicke-Maxwell theory
The black hole solutions in the higher dimensional Brans-Dicke-Maxwell theory
are investigated. We find that the presence of the nontrivial scalar field
depends on the spacetime dimensions (D). When D=4, the solution corresponds to
the Reissner-Nordstr\"{o}m black hole with a constant scalar field. In higher
dimensions (D>4), one finds the charged black hole solutions with the
nontrivial scalar field. The thermal properties of the charged black holes are
discussed and the reason why the nontrivial scalar field exists are explained.
Also the solutions for higher dimensional Brans-Dicke theory are given for
comparison.Comment: Revtex, 5 pages, no figures, contents were rewritten and new
references were adde
Quantum systems in weak gravitational fields
Fully covariant wave equations predict the existence of a class of
inertial-gravitational effects that can be tested experimentally. In these
equations inertia and gravity appear as external classical fields, but, by
conforming to general relativity, provide very valuable information on how
Einstein's views carry through in the world of the quantum.Comment: 22 pages. To be published in Proceedings of the 17th Course of the
International School of Cosmology and Gravitation "Advances in the interplay
between quantum and gravity physics" edited by V. De Sabbata and A.
Zheltukhin, Kluwer Academic Publishers, Dordrech
The role of flower pollen extract in managing patients affected by chronic prostatitis/chronic pelvic pain syndrome. a comprehensive analysis of all published clinical trials
Background: Chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) is still a challenge to manage for all physicians. We feel that a summary of the current literature and a systematic review to evaluate the therapeutic efficacy of flower pollen extract would be helpful for physicians who are considering a phytotherapeutic approach to treating patients with CP/CPPS. Methods: A comprehensive search of the PubMed and Embase databases up to June 2016 was performed. This comprehensive analysis included both pre-clinical and clinical trials on the role of flower pollen extract in CP/CPPS patients. Moreover, a meta-analysis of available randomized controlled trials (RCTs) was performed. The NIH Chronic Prostatitis Symptom Index (NIH-CPSI) and Quality of Life related questionnaires (QoL) were the most commonly used tools to evaluate the therapeutic efficacy of pollen extract. Results: Pre-clinical studies demonstrated the anti-inflammatory and anti-proliferative role of pollen extract. 6 clinical, non-controlled studies including 206 patients, and 4 RCTs including 384 patients were conducted. The mean response rate in non-controlled studies was 83.6% (62.2%-96.0%). The meta-analysis revealed that flower pollen extract could significantly improve patients’ quality of life [OR 0.52 (0.34-.0.81); p = 0.02]. No significant adverse events were reported. Conclusion: Most of these studies presented encouraging results in terms of variations in NIH-CPSI and QoL scores. These studies suggest that the use of flower pollen extract for the management of CP/CPPS patients is beneficial. Future publications of robust evidence from additional RCTs and longer-term follow-up would provide more support encouraging the use of flower pollen extracts for CP/CPPS patients
Bonding trends within ternary Isocoordinate chalcogenide glasses GeAsSe
A structural study is presented of ab-initio molecular dynamics simulations
of Ge-As-Se calcogenide glasses performed at the same mean coordination number
but differing stoichiometry ranging between Se rich and Se poor glasses.
Starting configurations are generated via Reverse Monte Carlo (RMC) simulations
of Extended X-ray Absorption Fine Structure (EXAFS) measurements of
experimental samples. Structural analysis is presented illustrating the bonding
trends found with changing stoichiometry.Comment: 26 pages, 9 figures. Submitted to Physical Review
Recommended from our members
A shared neural ensemble links distinct contextual memories encoded close in time.
Recent studies suggest that a shared neural ensemble may link distinct memories encoded close in time. According to the memory allocation hypothesis, learning triggers a temporary increase in neuronal excitability that biases the representation of a subsequent memory to the neuronal ensemble encoding the first memory, such that recall of one memory increases the likelihood of recalling the other memory. Here we show in mice that the overlap between the hippocampal CA1 ensembles activated by two distinct contexts acquired within a day is higher than when they are separated by a week. Several findings indicate that this overlap of neuronal ensembles links two contextual memories. First, fear paired with one context is transferred to a neutral context when the two contexts are acquired within a day but not across a week. Second, the first memory strengthens the second memory within a day but not across a week. Older mice, known to have lower CA1 excitability, do not show the overlap between ensembles, the transfer of fear between contexts, or the strengthening of the second memory. Finally, in aged mice, increasing cellular excitability and activating a common ensemble of CA1 neurons during two distinct context exposures rescued the deficit in linking memories. Taken together, these findings demonstrate that contextual memories encoded close in time are linked by directing storage into overlapping ensembles. Alteration of these processes by ageing could affect the temporal structure of memories, thus impairing efficient recall of related information
Inflationary Attractors in Gravity
In this letter we shall demonstrate that the viable gravities can be
classified mainly into two classes of inflationary attractors, either the
attractors or the -attractors. To show this, we shall derive the most
general relation between the tensor-to-scalar ratio and the spectral index
of primordial curvature perturbations , namely the relation, by
assuming that the slow-roll condition constrains the values of the slow-roll
indices. As we show, the relation between the tensor-to-scalar ratio and the
spectral index of the primordial curvature perturbations has the form , where the dimensionless parameter contains
higher derivatives of the gravity function with respect to the Ricci
scalar, and it is a function of the -foldings number and may also be a
function of the free parameters of the various gravity models. For
gravities which have a spectral index compatible with the observational
data and also yield , these belong to the -type of attractors,
with , and these are viable theories. Moreover, in the case
that takes larger values in specific ranges and is constant for a given
gravity, the resulting relation has the form , where is a constant. Thus we conclude that the viable
gravities may be classified into two limiting types of
relations, one identical to the model at leading order in , and one
similar to the -attractors relation, for the gravity
models that yield constant. Finally, we also discuss the case that is
not constant.Comment: PLB Accepte
Dark energy interacting with two fluids
A cosmological model of dark energy interacting with dark matter and another
general component of the universe is investigated. We found general constraints
on these models imposing an accelerated expansion. The same is also studied in
the case for holographic dark energy
- …