The BMW Deep X-ray Cluster Survey

We briefly describe the main features of the Brera Multi-Wavelet (BMW) survey of serendipitous X-ray clusters, based on the still unexploited ROSAT-HRI archival observations. Cluster candidates are selected from the general BMW catalogue of 20,000 sources based exclusively on their X-ray extension. Contrary to common wisdom, a clever selection of the HRI energy channels allows us to significantly reduce the background noise, thus greatly improving the ability to detect low surface-brightness sources as clusters. The resulting sample of ~250 candidates shows a very good sky coverage down to a flux \~3x10^-14 erg/s/cm^2 ([0.5-2.0] keV band), i.e comparable to existing PSPC-based deep survey, with a particularly interesting area of ~100 sq.deg. around fluxes ~10^-13 erg/s/cm^2, i.e. where highly-luminous, rare systems at z~0.6-1 can be detected. At the same time, the superior angular resolution of the instrument should avoid biases against intrinsically small systems, while easing the identification process (e.g. by spotting blends and AGN contaminants). While about 20% of the candidates are already identified with groups/clusters at z<0.3 on the DSS2 images, we have started a deep CCD imaging campaign to observe all sources associated to "blank fields". First results from these observations reveal a distant (z>0.5) bonafide cluster counterpart for ~80% of the targets.Comment: 3 pages, 2 figures; to appear in Proc. of the ESO/ECF/STSCI workshop on "Deep Fields", Garching Oct 2000, (Publ: Springer

Field testing a novel high residence positioning system for monitoring the fine‐scale movements of aquatic organisms

1. Acoustic telemetry is an important tool for studying the behaviour of aquatic organisms in the wild. 2. VEMCO high residence (HR) tags and receivers are a recent introduction in the field of acoustic telemetry and can be paired with existing algorithms (e.g. VEMCO positioning system [VPS]) to obtain high‐resolution two‐dimensional positioning data. 3. Here, we present results of the first documented field test of a VPS composed of HR receivers (hereafter, HR‐VPS). We performed a series of stationary and moving trials with HR tags (mean HR transmission period = 1.5 s) to evaluate the precision, accuracy and temporal capabilities of this positioning technology. In addition, we present a sample of data obtained for five European perch Perca fluviatilis implanted with HR tags (mean HR transmission period = 4 s) to illustrate how this technology can estimate the fine‐scale behaviour of aquatic animals. 4. Accuracy and precision estimates (median [5th–95th percentile]) of HR‐VPS positions for all stationary trials were 5.6 m (4.2–10.8 m) and 0.1 m (0.02–0.07 m), respectively, and depended on the location of tags within the receiver array. In moving tests, tracks generated by HR‐VPS closely mimicked those produced by a handheld GPS held over the tag, but these differed in location by an average of ≈9 m. 5. We found that estimates of animal speed and distance travelled for perch declined when positional data for acoustically tagged perch were thinned to mimic longer transmission periods. These data also revealed a trade‐off between capturing real nonlinear animal movements and the inclusion of positioning error. 6. Our results suggested that HR‐VPS can provide more representative estimates of movement metrics and offer an advancement for studying fine‐scale movements of aquatic organisms, but high‐precision survey techniques may be needed to test these systems

Theoretical correlation between possible evidences of neutrino chiral oscillations and polarization measurements

Reporting about the formalism with the Dirac equation we describe the dynamics of chiral oscillations for a fermionic particle non-minimally coupling with an external magnetic field. For massive particles, the chirality and helicity quantum numbers represent different physical quantities of representative importance in the study of chiral interactions, in particular, in the context of neutrino physics. After solving the interacting Hamiltonian (Dirac) equation for the corresponding {\em fermionic} Dirac-{\em type} particle (neutrino) and quantifying chiral oscillations in the Dirac wave packet framework, we avail the possibility of determining realistic neutrino chirality conversion rates by means of (helicity) polarization measurements. We notice that it can become feasible for some particular magnetic field configurations with large values of {\boldmath$B$} orthogonal to the direction of the propagating particle.Comment: 12 pages, 2 figure

Estudos ecopatológicos das doenças respiratórias dos suínos: prevalência e impacto econômico em sistemas de produçao dos Estados de Santa Catarina, Rio Grande do Sul e Paraná.

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Cluster Evolution in the ROSAT North Ecliptic Pole Survey

The deepest region of the ROSAT All-Sky Survey, at the North Ecliptic Pole, has been studied to produce a complete and unbiased X-ray selected sample of clusters of galaxies. This sample is used to investigate the nature of cluster evolution and explore potential implications for large-scale structure models. The survey is 99.6% optically identified. Spectroscopic redshifts have been measured for all the extragalactic identifications. In this Letter, first results on cluster evolution are presented based on a comparison between the number of the observed clusters in the North Ecliptic Pole survey and the number of expected clusters assuming no-evolution models. At z>0.3 there is a deficit of clusters with respect to the local universe which is significant at > 4.7sigma. The evolution appears to commence at L_{0.5-2.0} > 1.8x10^{44} erg s^{-1} in our data. The negative evolution goes in the same direction as the original EMSS result, the results from the 160 deg^{2} survey by Vikhlinin et al. (1998) and the recent results from the RDCS (Rosati et al. 2000). At lower redshifts there is no evidence for evolution, a result in agreement with these and other cluster surveys.Comment: 17 pages, 3 figures. Accepted for publication in ApJ Letter

The VIPERS Multi-Lambda Survey. II. Diving with massive galaxies in 22 square degrees since z = 1.5

We investigate the evolution of the galaxy stellar mass function (SMF) and stellar mass density from redshift z=0.2 to z=1.5 of a $K_{AB}$<22-selected sample with highly reliable photometric redshifts and over an unprecedentedly large area. Our study is based on NIR observations carried out with WIRCam at CFHT over the footprint of the VIPERS spectroscopic survey and benefits from the high quality optical photometry from the CFHTLS and UV observations with the GALEX satellite. The accuracy of our photometric redshifts is $\sigma_z$ < 0.03 and 0.05 for the bright ($i_{AB}$22.5) samples, respectively. The SMF is measured with ~760,000 galaxies down to $K_s$=22 and over an effective area of ~22.4 deg$^2$, the latter of which drastically reduces the statistical uncertainties (i.e. Poissonian error & cosmic variance). We point out the importance of a careful control of the photometric calibration, whose impact becomes quickly dominant when statistical uncertainties are reduced, which will be a major issue for future generation of cosmological surveys with, e.g. EUCLID or LSST. By exploring the rest-frame (NUV-r) vs (r-$K_s$) color-color diagram separating star-forming and quiescent galaxies, (1) we find that the density of very massive log($M_*/ M_{\odot}$) > 11.5 galaxies is largely dominated by quiescent galaxies and increases by a factor 2 from z~1 to z~0.2, which allows for additional mass assembly via dry mergers, (2) we confirm a scenario where star formation activity is impeded above a stellar mass log($M^*_{SF} / M_{\odot}$) = 10.64$\pm$0.01, a value that is found to be very stable at 0.2 < z < 1.5, (3) we discuss the existence of a main quenching channel that is followed by massive star-forming galaxies, and finally (4) we characterise another quenching mechanism required to explain the clear excess of low-mass quiescent galaxies observed at low redshift.Comment: 22 pages, 20 figures. Accepted for publication in A&A. Version to be publishe

Interrelationship of the kinin system, nitric oxide and eicosanoids in the antigen-induced arthritis in rabbits.

The aim of the present study was to investigate the interrelationship of the kinin system, nitric oxide and eicosanoids in the acute phase of antigen-induced arthritis (AIA) in rabbits. The arthritis was induced in immunized rabbits and the following parameters were evaluated 24 hours later: leukocyte influx (total and differential white cell count), vascular permeability (Evans's blue method), and synovial PMN cell infiltrate. PGE2 and LTB4 (radioimmunoassay) levels were quantified in the synovial fluid. The animals were pre-treated with 20mg/kg/day during 14 days with L-NAME or D-NAME and/or Enalapril (0.12 mg/kg/day-14 days), and/or the B2 antagonist of Bradykinin HOE 140 (0.9 mg/kg). Our results showed that L-NAME was effective in the prevention of AIA with reduction of all Inflammatory parameters analyzed. Enalapril partially reverted the L-NAME anti-inflammatory effects. The simultaneous treatment with HOE 140 abolished this reversion and returned the inflammatory parameters to the levels observed in L-NAME treated animals. Our results suggest that pressoric alterations induced by L-NAME could not account for all its anti-inflammatory action in this model of experimental arthritis. Additionally the contribution of the kinin system in AIA was characterized as well as its interaction with eicosanoids and nitric oxide

Enhanced solar anti-neutrino flux in random magnetic fields

We discuss the impact of the recent KamLAND constraint on the solar anti-neutrino flux on the analysis of solar neutrino data in the presence of Majorana neutrino transition magnetic moments and solar magnetic fields. We consider different stationary solar magnetic field models, both regular and random, highlighting the strong enhancement in the anti-neutrino production rates that characterize turbulent solar magnetic field models. Moreover, we show that for such magnetic fields inside the Sun, one can constrain the intrinsic neutrino magnetic moment down to the level of mu_nu lessthan few times 10^-12 x mu_B irrespective of details of the underlying turbulence model. This limit is more stringent than all current experimental sensitivities, and similar to the most stringent bounds obtained from stellar cooling. We also comment on the robustness of this limit and show that at most it might be weakened by one order of magnitude, under very unlikely circumstances.Comment: 25 pages, 5 figures; final version to appear in Phys. Rev.

Global Analysis of the post-SNO Solar Neutrino Data for Standard and Non-Standard Oscillation Mechanisms

What can we learn from solar neutrino observations? Is there any solution to the solar neutrino anomaly which is favored by the present experimental panorama? After SNO results, is it possible to affirm that neutrinos have mass? In order to answer such questions we analyze the current available data from the solar neutrino experiments, including the recent SNO result, in view of many acceptable solutions to the solar neutrino problem based on different conversion mechanisms, for the first time, using the same statistical procedure. This allows us to do a direct comparison of the goodness of the fit among different solutions, from which we can discuss and conclude on the current status of each proposed dynamical mechanism. These solutions are based on different assumptions: (a) neutrino mass and mixing, (b) non-vanishing neutrino magnetic moment, (c) the existence of non-standard flavor-changing and non-universal neutrino interactions and (d) the tiny violation of the equivalence principle. We investigate the quality of the fit provided by each one of these solutions not only to the total rate measured by all the solar neutrino experiments but also to the recoil electron energy spectrum measured at different zenith angles by the Super-Kamiokande collaboration. We conclude that several non-standard neutrino flavor conversion mechanisms provide a very good fit to the experimental data which is comparable with (or even slightly better than) the most famous solution to the solar neutrino anomaly based on the neutrino oscillation induced by mass.Comment: Minor changes in the solar magnetic field profile used, and some refferences added. Final version to appear in PR

Estudo da suscetibilidade ao escurecimento por radiação gama de quartzo róseo-leitoso da província pegmatítica da Borborema

Este estudo considera as transformações induzidas pela radiação γ sobre os defeitos estruturais em quartzo róseo e leitoso da Província Pegmatítica da Borborema (Paraíba e Rio Grande do Norte, Brasil). Amostras de coloração rósea e leitosa foram irradiadas com doses de raios γ (60Co) entre 0,5 e 96 kGy. Defeitos pontuais relacionados às impurezas de Al, Ge, Li e grupos OH foram caracterizados por espectroscopias ultravioleta visível e infravermelha e ressonância paramagnética eletrônica, antes e após a irradiação. A espectrometria de massa com plasma indutivamente acoplado foi empregada para quantificar as concentrações de Al, Li, Ge, Fe, Ti e outras impurezas em fragmentos de diferentes tonalidades. Constatou-se que os defeitos [AlO4]0, [AlO4/H]0 e [GeO4/Li]0 são formados pela dissociação dos defeitos [AlO4/Li]0 e [Li-OH], a partir de doses de 0,5 kGy. A diminuição do sinal da ressonância paramagnética eletrônica do centro [GeO4/Li]0 e a formação de centros E'1 perturbados por Ge para doses acima de 8 kGy confirmou a grande mobilidade dos íons Li+ pela estrutura do quartzo. O aumento da população de defeitos [AlO4]0 e o consequente escurecimento das amostras foi semelhante para ambos os tipos de quartzo. Análises preliminares por microscopia eletrônica mostraram a presença de fibras nanométricas apenas no resíduo da digestão ácida de amostras róseas, indicando que a coloração rósea do quartzo da Província Pegmatítica da Borborema está provavelmente relacionada às inclusões de dumortierita