Tests of flavor symmetry in J/psi decays

We use SU(3) flavor symmetry to analyze the $PP', VP$ and baryon-antibaryon decays of $J/\psi$. Both, the SU(3)-invariant and -violating contributions are considered. Particular attention is paid to the interference of the electromagnetic and strong amplitudes.Comment: 8 pages, latex. Talk given at CAM-94 Physics Meetin

Sheep Grazing Patterns for Better Land Management: Adjusting GPS Tracking Protocol

Small ruminant livestock systems in northeast Portugal are an extensive activity based on daily grazing paths across the landscape. The flocks use multiple patches of multiple land cover types in different ways throughout the year. Shepherd and flock interactions determine the resting and feeding spots utilized by sheep and goats according to the biotic and abiotic conditions. Information about the herding home range is central to managing the land use and vegetation cover and optimizing sheep and goats\u27 productivity in traditional systems. This study\u27s main objective is to contribute to calibrate a shepherding GPS protocol to monitor sheep flocks based on fieldwork in Vimieiro (Mirandela) on a protected area of the European Natura 2000 network. We answer two farmers\u27 and breeders\u27 requests for using GPS collars to monitor the landscape usage by sheep: (1) How closely do collared sheep remain within the flock? (2) How do the collars perform on different logging frequencies to estimate patch occupancy? We analyzed the grazing paths based on three collars\u27 5-minute GPS positions from winter to summer solstices. We investigated the differences in extent, duration, and frequency data of each collar throughout the season change based on spatial regressions. Results show no significant differences among the three collars ranges. It also indicates that positions collected every 15 and 30 minutes could be adequate. It means that a flock monitoring low cost can be generalized, providing accurate information to manage the pastoral territory and increase the small ruminant\u27s productivit

Solid flow drives surface nanopatterning by ion-beam irradiation

Ion Beam Sputtering (IBS) is known to produce surface nanopatterns over macroscopic areas on a wide range of materials. However, in spite of the technological potential of this route to nanostructuring, the physical process by which these surfaces self-organize remains poorly under- stood. We have performed detailed experiments of IBS on Si substrates that validate dynamical and morphological predictions from a hydrodynamic description of the phenomenon. Our results elucidate flow of a nanoscopically thin and highly viscous surface layer, driven by the stress created by the ion-beam, as a description of the system. This type of slow relaxation is akin to flow of macroscopic solids like glaciers or lead pipes, that is driven by defect dynamics.Comment: 12 pages, 4 figure

CCD Photometry of Delta Scuti stars 7 Aql and 8 Aql

As a continuation of the study of the Delta Scuti stars 7 Aql and 8 Aql; new CCD photometric data were acquired in 2007. We present a period analysis on these data that confirm the dominant modes detected in each star in the framework of the STEPHI XII campaign in 2003.Comment: 9 pages, 7 figures, 2 tables; Accepted for publication in Communications in Asteroseismology, Vol 153, 200

Interferometric observations of SiO thermal emission in the inner wind of M-type AGB stars IK Tauri and IRC+10011

Context. AGB stars go through a process of strong mass-loss that involves pulsations of the atmosphere, which extends to a region where the conditions are adequate for dust grains to form. Radiation pressure acts on these grains which, coupled to the gas, drive a massive outflow. The details of this process are not clear, including which molecules are involved in the condensation of dust grains. Aims. To study the role of the SiO molecule in the process of dust formation and mass-loss in M-type AGB stars. Methods. Using the IRAM NOEMA interferometer we observed the $^{28}$SiO and $^{29}$SiO $J=3-2$, $v=0$ emission from the inner circumstellar envelope of the evolved stars IK Tau and IRC+10011. We computed azimuthally averaged emission profiles to compare the observations to models using a molecular excitation and ray-tracing code for SiO thermal emission. Results. We observed circular symmetry in the emission distribution. We also found that the source diameter varies only marginally with radial velocity, which is not the expected behavior for envelopes expanding at an almost constant velocity. The adopted density, velocity, and abundance laws, together with the mass-loss rate, which best fit the observations, give us information on the chemical behavior of the SiO molecule and its role in the dust formation process. Conclusions. The results indicate that there is a strong coupling between the depletion of gas phase SiO and gas acceleration in the inner envelope. This could be explained by the condensation of SiO into dust grains

Accurate fundamental parameters and distance to a massive early-type eclipsing binary in the Danks 2 cluster

We present a study of the properties of the O-type, massive eclipsing binary 2MASS J13130841-6239275 located in the outskirts of the Danks 2 cluster in the G305 star-forming complex, using near-infrared spectroscopy from VLT/ISAAC. We derive the masses and radii to be 24.5$\pm$0.9 M$_{\odot}$ and 9.2$\pm$0.1 R$_{\odot}$ for the primary and 21.7$\pm$0.8 M$_{\odot}$ and 8.7$\pm$0.1 R$_{\odot}$ for the secondary component. In addition, we evaluate the sensitivity of our parameters to the choice of the spectral features used to determine the radial velocities. Both components appear to be main-sequence O6.5$-$O7 type stars at an age of $\sim$5 Myr, which is in agreement with the age of the cluster. A high visual extinction of A$_{5495}$=11.9$\pm$0.1 mag is reported, which is likely attributed to the cold molecular gas contaminating the north-east region of the cluster. By fitting the spectral energy distribution of the system to the available $BVI_{c}JHK_{s}$ photometry, we determine a distance to the system of 3.52$\pm$0.08 kpc with a precision of 2$\%$, which is the most well-determined distance to the Danks 2 cluster and the host complex reported in the literature.Comment: 13 pages, 9 figures, 6 tables. Accepted for publication in A&