Palomar 13: a velocity dispersion inflated by binaries ?

Recently, combining radial velocities from Keck/HIRES echelle spectra with published proper motion membership probabilities, Cote et al (2002) observed a sample of 21 stars, probable members of Palomar 13, a globular cluster in the Galactic halo. Their projected velocity dispersion sigma_p = 2.2 +/-0.4 km/s gives a mass-to-light ratio M/L_V = 40 +24/-17, about one order of magnitude larger than the usual estimate for globular clusters. We present here radial velocities measured from three different CCD frames of commissioning observations obtained with the new ESO/VLT instrument FLAMES (Fibre Large Array Multi Element Spectrograph). From these data, now publicly available, we measure the homogeneous radial velocities of eight probable members of this globular cluster. A new projected velocity dispersion sigma_p = 0.6-0.9 +/-0.3 km/s implies Palomar 13 mass-to-light ratio M/L_V = 3-7, similar to the usual value for globular clusters. We discuss briefly the two most obvious reasons for the previous unusual mass-to-light ratio finding: binaries, now clearly detected, and more homogeneous data from the multi-fibre FLAMES spectrograph.Comment: 9 pages, 2 Postscript figure

Effect of feeding streptococcus faecium to artificially reared pigs

Two trials were conducted with a total of 112 artificially reared pigs to evaluate the effect feeding Streptococcus faecium. The areas studied were growth and feed efficiency, mortality rate, daily scour score, blood parameters (total leukocyte numbers and differentials), and in vivo determination of cell-mediated immunity. The results of the trial indicate that there was no significant advantage to feeding Streptococcus faecium to artificially reared pigs.; Swine Day, Manhattan, KS, November 10, 198

Cellular immune responses in artificially reared pigs

An experiment was conducted to determine the influence of artificial rearing on the cellular immune response of young pigs. Artificially reared pigs had lower cellular immune reactivity than sow-reared controls. These results indicate that artificial rearing may result in immunosuppression in young pigs.; Swine Day, Manhattan, KS, November 15, 198

Growing supermassive black holes in the late stages of galaxy mergers are heavily obscured

Mergers of galaxies are thought to cause significant gas inflows to the inner parsecs, which can activate rapid accretion onto supermassive black holes (SMBHs), giving rise to Active Galactic Nuclei (AGN). During a significant fraction of this process, SMBHs are predicted to be enshrouded by gas and dust. Studying 52 galactic nuclei in infrared-selected local Luminous and Ultra-luminous infrared galaxies in different merger stages in the hard X-ray band, where radiation is less affected by absorption, we find that the amount of material around SMBHs increases during the last phases of the merger. We find that the fraction of Compton-thick (CT, $N_{\rm\,H}\geq 10^{24}\rm\,cm^{-2}$) AGN in late merger galaxies is higher ($f_{\rm\,CT}=65^{+12}_{-13}\%$) than in local hard X-ray selected AGN ($f_{\rm\,CT}=27\pm 4\%$), and that obscuration reaches its maximum when the nuclei of the two merging galaxies are at a projected distance of $D_{12}\simeq0.4-10.8$ kiloparsecs ($f_{\rm\,CT}=77_{-17}^{+13}\%$). We also find that all AGN of our sample in late merger galaxies have $N_{\rm\,H}> 10^{23}\rm\,cm^{-2}$, which implies that the obscuring material covers $95^{+4}_{-8}\%$ of the X-ray source. These observations show that the material is most effectively funnelled from the galactic scale to the inner tens of parsecs during the late stages of galaxy mergers, and that the close environment of SMBHs in advanced mergers is richer in gas and dust with respect to that of SMBHs in isolated galaxies, and cannot be explained by the classical AGN unification model in which the torus is responsible for the obscuration.Comment: Final version matching the article published in MNRAS - 30 pages, 16 figure

Imaging Active Infection in vivo Using D-Amino Acid Derived PET Radiotracers.

Occult bacterial infections represent a worldwide health problem. Differentiating active bacterial infection from sterile inflammation can be difficult using current imaging tools. Present clinically viable methodologies either detect morphologic changes (CT/ MR), recruitment of immune cells (111In-WBC SPECT), or enhanced glycolytic flux seen in inflammatory cells (18F-FDG PET). However, these strategies are often inadequate to detect bacterial infection and are not specific for living bacteria. Recent approaches have taken advantage of key metabolic differences between prokaryotic and eukaryotic organisms, allowing easier distinction between bacteria and their host. In this report, we exploited one key difference, bacterial cell wall biosynthesis, to detect living bacteria using a positron-labeled D-amino acid. After screening several 14C D-amino acids for their incorporation into E. coli in culture, we identified D-methionine as a probe with outstanding radiopharmaceutical potential. Based on an analogous procedure to that used for L-[methyl-11C]methionine ([11C] L-Met), we developed an enhanced asymmetric synthesis of D-[methyl-11C]methionine ([11C] D-Met), and showed that it can rapidly and selectively differentiate both E. coli and S. aureus infections from sterile inflammation in vivo. We believe that the ease of [11C] D-Met radiosynthesis, coupled with its rapid and specific in vivo bacterial accumulation, make it an attractive radiotracer for infection imaging in clinical practice

Análise das frequências alélicas e genotípicas de polimorfismos nos genes da calpaína e da calpastatina em bovinos de corte.

Trabalho 1

Enhanced tidal disruption rates from massive black hole binaries

"Hard" massive black hole (MBH) binaries embedded in steep stellar cusps can shrink via three-body slingshot interactions. We show that this process will inevitably be accompanied by a burst of stellar tidal disruptions, at a rate that can be several orders of magnitude larger than that appropriate for a single MBH. Our numerical scattering experiments reveal that: 1) a significant fraction of stars initially bound to the primary hole are scattered into its tidal disruption loss cone by gravitational interactions with the secondary hole, an enhancement effect that is more pronounced for very unequal-mass binaries; 2) about 25% (40%) of all strongly interacting stars are tidally disrupted by a MBH binary of mass ratio q=1/81 (q=1/243) and eccentricity 0.1; and 3) two mechanisms dominate the fueling of the tidal disruption loss cone, a Kozai non-resonant interaction that causes the secular evolution of the stellar angular momentum in the field of the binary, and the effect of close encounters with the secondary hole that change the stellar orbital parameters in a chaotic way. For a hard MBH binary of 10^7 solar masses and mass ratio 0.01, embedded in an isothermal stellar cusp of velocity dispersion sigma*=100 km/s, the tidal disruption rate can be as large as 1/yr. This is 4 orders of magnitude higher than estimated for a single MBH fed by two-body relaxation. When applied to the case of a putative intermediate-mass black hole inspiraling onto Sgr A*, our results predict tidal disruption rates ~0.05-0.1/yr.Comment: 5 pages, 3 figures, accepted for publication in the Astrophysical Journal Letter

Avaliação do polimorfismo CAST/Xmnl em bovinos de corte.

A utilização de testes de DNA para a identificação precoce de animais que apresentam potencial para produção de carne bovina de qualidade constitui uma importante ferramenta para viabilizar a seleção dos reprodutores e aumentar a qualidade da carne do rebanho comercial. Outro fator que contribui para o aumento da qualidade da carne são os cruzamentos utilizando raças das subespécies Bos taurus indicus e Bos taurus taurus, pois sabe-se que quanto maior a proporção de sangue zebuíno no rebanho, menores são os valores de maciez encontrados. Até o momento, vários genes relacionados com essa característica foram identificados, sendo um deles o gene CAST, que codifica a enzima calpastatina. Neste contexto, o objetivo deste trabalho foi avaliar as frequências alélicas e genotípicas do polimorfismo CAST/XmnI nas raças Bonsmara, Caracu e Senepol (taurinas adaptadas), Nelore (zebuína) e Angus (taurina não adaptada), visando orientar a escolha de uma raça taurina adaptada para produção de carne de qualidade em sistemas de cruzamento. Para a extração do DNA, foram obtidas amostras de sêmen e de sangue de 111 touros escolhidos de acordo com a genealogia e com o menor grau de parentesco possível. A genotipagem foi realizada pela técnica PCR-RFLP e as frequências alélicas e genotípicas foram comparadas utilizando o teste de Qui-quadrado. Houve diferença significativa nas frequências alélicas e genotípicas entre as raças (p<0,05), sendo que as raças Angus e Bonsmara apresentaram os maiores valores de frequência para o alelo A (88,6%). A raça Nelore foi a que apresentou maior frequência para o alelo B (54,2%), seguida pela Caracu (36,4%) e pela Senepol (28,6%). Esse marcador mostrou-se viável para seleção de bovinos, já que a alta frequência do alelo A, observada na população em estudo, permite que o teste seja aplicado, desde que confirmada a associação desse polimorfismo com a maciez da carne