Measurement of the LCG2 and glite file catalogue's performance

When the Large Hadron Collider (LHC) begins operation at CERN in 2007 it will produce data in volumes never before seen. Physicists around the world will manage, distribute and analyse petabytes of this data using the middleware provided by the LHC Computing Grid. One of the critical factors in the smooth running of this system is the performance of the file catalogues which allow users to access their files with a logical filename without knowing their physical location. This paper presents a detailed study comparing the performance and respective merits and shortcomings of two of the main catalogues: the LCG File Catalogue and the gLite FiReMan catalogue

Detecting transit signatures of exoplanetary rings using SOAP3.0

CONTEXT. It is theoretically possible for rings to have formed around extrasolar planets in a similar way to that in which they formed around the giant planets in our solar system. However, no such rings have been detected to date. AIMS: We aim to test the possibility of detecting rings around exoplanets by investigating the photometric and spectroscopic ring signatures in high-precision transit signals. METHODS: The photometric and spectroscopic transit signals of a ringed planet is expected to show deviations from that of a spherical planet. We used these deviations to quantify the detectability of rings. We present SOAP3.0 which is a numerical tool to simulate ringed planet transits and measure ring detectability based on amplitudes of the residuals between the ringed planet signal and best fit ringless model. RESULTS: We find that it is possible to detect the photometric and spectroscopic signature of near edge-on rings especially around planets with high impact parameter. Time resolution $\leq$ 7 mins is required for the photometric detection, while 15 mins is sufficient for the spectroscopic detection. We also show that future instruments like CHEOPS and ESPRESSO, with precisions that allow ring signatures to be well above their noise-level, present good prospects for detecting rings.Comment: 13 pages, 16 figures, 2 tables , accepted for publication in A&

Are Stars with Planets Polluted?

We compare the metallicities of stars with radial velocity planets to the metallicity of a sample of field dwarfs. We confirm recent work indicating that the stars-with-planet sample as a whole is iron rich. However, the lowest mass stars tend to be iron poor, with several having [Fe/H]<-0.2, demonstrating that high metallicity is not required for the formation of short period Jupiter-mass planets. We show that the average [Fe/H] increases with increasing stellar mass (for masses below 1.25 solar masses) in both samples, but that the increase is much more rapid in the stars-with-planet sample. The variation of metallicity with stellar age also differs between the two samples. We examine possible selection effects related to variations in the sensitivity of radial velocity surveys with stellar mass and metallicity, and identify a color cutoff (B-V>0.48) that contributes to but does not explain the mass-metallicity trend in the stars-with-planets sample. We use Monte Carlo models to show that adding an average of 6.5 Earth masses of iron to each star can explain both the mass-metallicity and the age-metallicity relations of the stars-with-planets sample. However, for at least one star, HD 38529, there is good evidence that the bulk metallicity is high. We conclude that the observed metallicities and metallicity trends are the result of the interaction of three effects; accretion of about 6 Earth masses of iron rich material, selection effects, and in some cases, high intrinsic metallicity.Comment: 19 pages 11 figure

Dynamical control of electron spin coherence in a quantum dot

We investigate the performance of dynamical decoupling methods at suppressing electron spin decoherence from a low-temperature nuclear spin reservoir in a quantum dot. The controlled dynamics is studied through exact numerical simulation, with emphasis on realistic pulse delays and long-time limit. Our results show that optimal performance for this system is attained by a periodic protocol exploiting concatenated design, with control rates substantially slower than expected from the upper spectral cutoff of the bath. For a known initial electron spin state, coherence can saturate at long times, signaling the creation of a stable ``spin-locked'' decoherence-free subspace. Analytical insight on saturation is obtained for a simple echo protocol, in good agreement with numerical results.Comment: 4 pages, 4 figures with 3 of them in colo

Uso de promotores de crescimento para cabritos leiteiros, fase de aleitamento.

A fase de aleitamento de cabritos leiteiros esta inserida no periodo de seu maior potencial de crescimento. Nesta fase, os animais sao susceptiveis as enterites (diarreias) de origem alimentar e/ou infecciosa, consideradas como a principais causas de baixo desempenho de cabritos. Assim, este experimento foi conduzido para avaliar o efeito de promotores de crescimento sobre o desempenho de cabritos leiteiros, na fase de aleitamento. Foram utilizados 30 crias, femeas, sendo 15 da raca Saanen e 15 da raca Anglo-Nubiana. Os animais foram aleitados com leite de vaca durante todo o periodo experimental e receberam capim elefante e concentrado ad libitum a partir de 15 dias de idade. Os tratamentos foram: T1= leite de vaca, T2= leite de vaca+salinomicina e T3= leite de vaca+probiotico. Os resultados mostraram que nao houve diferenca (P>0,05) entre tratamentos. Os valores encontrados para ganho de peso (g/animal/dia) e para peso ao desaleitamento (Kg) foram: 126,5 126,8, 122,4 e 10,2, 10,4 e 10,0, respectivamente. Nao foi observado ocorrencia de enterite nos animais. Entre raca, tambem, nao foi detectada diferenca (P>0,05) significativa. [Use of growth promotors for dairy kids, at the suckling phase]. The suckling phase of dairy kids is the period of higher potential for growth. In this phase, the animals are susceptible to the alimentary and infectious enteritis. These types of enteritis are the principal cause of low kid's performance. So, this experiment was carried out to evaluate the effect of growth promoters on performance of dairy kids during the suckling phase. Thirty females kids of the Anglo-nubiana breed (15) and of the Saanen breed (15) were used. The animals were artificially reared with cow milk, during the trial and they received napiergrass (Pennisetum purpureum) and concentrate ad libitum after 15 days of age. The treatments were T1 - cow milk, T2 - cow milk + salinomicine T3 - cow milk + probiotic. The results showed that there was no significant difference (P>0.05) among treatments and breed. The values to weight gain (g/animal/day) and wean weight (kg/animal) were 126.5, 126.8, 122.4 e 10.2, 10.4 e 10.0, respectively. There was not enteritis in animals

The CORALIE survey for southern extra-solar planets. X. A Hot Jupiter orbiting HD73256

Recent radial-velocity measurements obtained with the CORALIE spectrograph on the 1.2-m Euler Swiss telescope at La Silla unveil the presence of a new Jovian-mass Hot Jupiter around HD 73256. The 1.85-M_Jup planet moves on an extremely short-period (P=2.5486 d), quasi-circular orbit. The best Keplerian orbital solution is presented together with an unsuccessful photometric planetary-transit search performed with the SAT Danish telescope at La Silla. Over the time span of the observations, the photometric follow-up of the candidate has nevertheless revealed a P=14-d photometric periodicity corresponding to the rotational period of the star. This variation as well as the radial-velocity jitter around the Keplerian solution are shown to be related to the fair activity level known for HD 73256.Comment: 7 pages, 7 figures. Accepted in A&