Visser's Massive Gravity Bimetric Theory Revisited

A massive gravity theory was proposed by Visser in the late nineties. This theory, based on a backgroung metric $b_{\alpha \beta}$ and on an usual dynamical metric $g_{\alpha \beta}$ has the advantage of being free of ghosts as well as discontinuities present in other massive theories proposed in the past. In the present investigation, the equations of Visser's theory are revisited with a particular care on the related conservation laws.\ It will be shown that a multiplicative factor is missing in the graviton tensor originally derived by Visser, which has no incidence on the weak field approach but becomes important in the strong field regime when, for instance, cosmological applications are considered. In this case, contrary to some previous claims found in the literature, we conclude that a non-static background metric is required in order to obtain a solution able to mimic the $\Lambda$CDM cosmology.Comment: 10 pages - Accepted for publication in Physical Review

Determining Sneutrino Masses and Physical Implications

In some areas of supersymmetry parameter space, sneutrinos are lighter than the charginos and the next-to-lightest neutralino, and they decay into the invisible neutrino plus lightest-neutralino channel with probability one. In such a scenario they can be searched for in decays of charginos that are pair-produced in e+e- collisions, and in associated sneutrino-chargino production in photon-electron collisions. The sneutrino properties can be determined with high accuracy from the edges of the decay energy spectra in the first case and from threshold scans in the second. In the final part of the report we investigate the mass difference of sneutrinos and charged sleptons between the third and the first two generations in seesaw-type models of the neutrino/sneutrino sector. For a wide range these mass differences are sensitive to the seesaw scale.Comment: 20 p

Determination of phytoextraction potential of plant speciesfor toxic elements in soils of abandoned sulphide-mining areas

This study has determined contamination levels in soils and plants from the Sa˜o Domingos mining area, Portugal, by k0-INAA. Total concentrations of As, Sb, Cr, Hg, Cu, Zn and Fe in soils were very high, exceeding the maximum limits in Portuguese legislation. Concentrations of toxic elements like As, Sb and Zn were highest in roots of Erica andevalensis, Juncus acutus, Agrostis castellana and Nicotiana glauca. Additionally, As, Br, Cr, Fe, Sb and Zn in all organs of most plants were above toxicity levels. Those species that accumulated relatively high concentrations of toxic elements in roots (and tops) may be cultivated for phytostabilisation of similar areas

Effects of training on sand or hard surfaces on sprint and jump performance of team-sport players: a systematic review with meta-analysis

We examined the effectiveness of training on sand and compared the effects of sand and hard surface training programs on the sprint and jump performance of team-sport players. PubMed MEDLINE, SPORTDiscus, and Web of Science databases were used in the literature search. A total of 377 records were initially identified and six studies comprising 136 athletes were included in the meta-analysis. Pre- and post-comparisons showed that sand training interventions were effective at improving both jump and sprint capacities. When comparing sand and hard surfaces, no significant differences in favor of any of the interventions were observed. In summary, this review revealed that sand training is an efficient strategy to improve jump and sprint performances in team-sport players. Moreover, sand surfaces produced similar gains to those observed after hard surface training schemes. Strength and conditioning coaches and sport scientists who work with team-sports can use both sand and hard surface training programs as part of their regular training practices, during distinct phases of the season

Maximum strength, relative strength, and strength deficit: relationships with performance and differences between elite sprinters and professional rugby union players

Purpose: To test the relationships between maximum and relative strength (MS and RS), absolute and relative peak force (PF and RPF), and strength deficit (SDef), with sprint and jump performance, and to compare these mechanical variables between elite sprinters and professional rugby union players. Methods: Thirty-five male rugby union players and thirty male sprinters performed vertical jumps, 30-m sprint, and the half-squat one-repetition maximum (1RM) assessment, where these force-related parameters were collected. Pearson correlation coefficient was used to test the relationships among the variables. An independent t-test and magnitude-based inferences compared the mechanical variables between sprinters and rugby players. Results: Almost certain significant differences were observed for jump and sprint performance between the groups (P < 0.0001). Rugby union players demonstrated a likely significant higher MS (P = 0.03), but a very likely lower RS (P = 0.007) than sprinters. No significant differences were observed for PF between them. Sprinters exhibited an almost certain significant higher RPF than rugby players (P < 0.0001). Furthermore, rugby players demonstrated almost certain to likely significant higher SDef from 40 to 70% 1RM (P < 0.05) compared to sprinters. Overall, all strength-derived parameters were significantly related to functional performance. Conclusions: Elite sprinters present higher levels of RS and RPF, lower levels of SDef, and superior sprint and jump performance than professional rugby players. Relative strength-derived values (RS and RPF) and SDef are significantly associated with speed-power measures and may be used as effective and practical indicators of athletic performance

Outflows in the Narrow Line Region of Bright Seyfert Galaxies - I: GMOS-IFU Data

We present two-dimensional maps of emission-line fluxes and kinematics, as well as of the stellar kinematics of the central few kpc of five bright nearby Seyfert galaxies -- Mrk\,6, Mrk\,79, Mrk\,348, Mrk\,607 and Mrk\,1058 -- obtained from observations with the Gemini Multi-Object Spectrograph (GMOS) Integral Field Unit (IFU) on the Gemini North Telescope. The data cover the inner 3\farcs5$\times$5\farcs0 -- corresponding to physical scales in the range 0.6$\times$0.9 to 1.5$\times$2.2\,kpc$^2$ -- at a spatial resolution ranging from 110 to 280 pc with a spectral coverage of 4300 -- 7100\,\AA\ and velocity resolution of $\approx$ 90\,km\,s$^{-1}$. The gas excitation is Seyfert like everywhere but show excitation, but show excitation gradients that are correlated with the gas kinematics, reddening and/or the gas density. The gas kinematics show in all cases two components: a rotation one similar to that observed in the stellar velocity field, and an outflow component. In the case of Mrk607, the gas is counter-rotating relative to the stars. Enhanced gas velocity dispersion is observed in association to the outflows according to two patterns: at the locations of the highest outflow velocities along the ionization axis or perpendicularly to it in a strip centered at the nucleus that we attribute to an equatorial outflow. Bipolar outflows are observed in Mrk\,348 and Mrk\,79, while in Mrk\,1058 only the blueshifted part is clearly observed, while in the cases of Mrk\,6 and Mrk\,607 the geometry of the outflow needs further constraints from modeling to be presented in a forthcoming study, where the mass flow rate and powers will also be obtained.Comment: 20 pages, accepted by MNRA

Association of ADAMTS7 gene polymorphism with cardiovascular survival in coronary artery disease

Recent genetic studies have revealed an association between polymorphisms at the ADAMTS7 gene locus and coronary artery disease (CAD) risk. Functional studies have shown that a CAD-associated polymorphism (rs3825807) affects ADAMTS7 maturation and vascular smooth muscular cell (VSMC) migration. Here, we tested whether ADAMTS7 (A/G) SNP is associated with cardiovascular (CV) survival in patients with established CAD. A cohort of 1,128 patients with angiographic proven CAD, who were followed up prospectively for a mean follow-up period of 63 (range 6-182) mo, were genotyped for rs3825807 A/G. Survival statistics (Cox regression) compared heterozygous (AG) and wild-type (AA) with the reference homozygous GG. Kaplan-Meier (K-M) survival curves were performed according to ADAMTS7 genotypes for CV mortality. Results showed that 47.3% of patients were heterozygous (AG), 36.5% were homozygous for the wild-type allele (AA) and only 16.2% were homozygous for the GG genotype. During the follow-up period, 109 (9.7%) patients died, 77 (6.8%) of CV causes. Survival analysis showed that AA genotype was an independent risk factor for CV mortality compared with reference genotype GG (HR = 2.7, P = 0.025). At the end of follow-up, the estimated survival probability (K-M) was 89.8% for GG genotype, 82.2% for AG and 72.3% for AA genotype (P = 0.039). Carriage of the mutant G allele of the ADAMTS7 gene was associated with improved CV survival in patients with documented CAD. The native overfunctional ADAMTS7 allele (A) may accelerate VSMC migration and lead to neointimal thickening, atherosclerosis progression and acute plaque events. ADAMTS7 gene should be further explored in CAD for risk prediction, mechanistic and therapeutic goals.info:eu-repo/semantics/publishedVersio