The stellar content of the infalling molecular clump G286.21+0.17

The early evolution during massive star cluster formation is still uncertain. Observing embedded clusters at their earliest stages of formation can provide insight into the spatial and temporal distribution of the stars and thus probe different star cluster formation models. We present near-infrared imaging of an 8'*13'(5.4pc*8.7pc) region around the massive infalling clump G286.21+0.17(also known as BYF73). The stellar content across the field is determined and photometry is derived in order to { obtain} stellar parameters for the cluster members. We find evidence for some sub-structure (on scales less than a pc diameter) within the region with apparently at least three different sub-clusters associated with the molecular clump based on differences in extinction and disk fractions. At the center of the clump we identify a deeply embedded sub-cluster. Near-infrared excess is detected for 39-44% in the two sub-clusters associated with molecular material and 27% for the exposed cluster. Using the disk excess as a proxy for age this suggests the clusters are very young. The current total stellar mass is estimated to be at least 200 Msun. The molecular core hosts a rich population of pre-main sequence stars. There is evidence for multiple events of star formation both in terms of the spatial distribution within the star forming region and possibly from the disk frequency.Comment: Submitted to A

On the Globular Cluster IMF below 1 Solar Mass

(Abridged) Accurate luminosity functions (LF) for a dozen globular clusters have now been measured at or just beyond their half-light radius using HST. They span almost the entire cluster main sequence below ~ 0.75 Msolar. All these clusters exhibit LF that rise continuously from an absolute I magnitude M_I ~ 6 to a peak at M_I ~ 8.5-9 and then drop with increasing M_I. Transformation of the LF into mass functions (MF) by means of the most recent mass luminosity relations that are consistent with all presently available data on the physical properties of low mass, low metallicity stars shows that all the LF observed so far can be obtained from MF having the shape of a log-normal distribution with characteristic mass m_c=0.33 +/- 0.03 Msolar and standard deviation sigma = 1.81 +/- 0.19. After correction for the effects of mass segregation, the variation of the ratio of the number of higher to lower mass stars with cluster mass or any simple orbital parameter or the expected time to disruption recently computed for these clusters shows no statistically significant trend over a range of this last parameter of more than a factor of 100. We conclude that the global MF of these clusters have not been measurably modified by evaporation and tidal interactions with the Galaxy and, thus, should reflect the initial distribution of stellar masses. Since the log-normal function that we find is also very similar to the one obtained independently for much younger clusters and to the form expected theoretically, the implication seems to be unavoidable that it represents the true stellar IMF for this type of stars in this mass range.Comment: Accepted for publication in The Astrophysical Journal. Contains 28 pages with 6 figure

Mass accretion rates from multiband photometry in the Carina Nebula: The case of Trumpler 14

open8siWe present a study of the mass accretion rates of pre-main sequence (PMS) stars in the cluster Trumpler 14 (Tr 14) in the Carina Nebula. Using optical multiband photometry we were able to identify 356 PMS stars showing Hα excess emission with equivalent width EW(Hα) > 20 Å. We interpret this observational feature as an indication that these objects are still actively accreting gas from their circumstellar medium. From a comparison of the HR diagram with PMS evolutionary models we derive ages and masses of the PMS stars. We find that most of the PMS objects are younger than 10 Myr with a median age of ~3 Myr. Surprisingly, we also find that ~20% of the mass accreting objects are older than 10 Myr. For each PMS star in Trumpler 14 we determine the mass accretion rate (Ṁacc) and discuss its dependence on mass and age. We finally combine the optical photometry with near-IR observations to build the spectral energy distribution (SED) for each PMS star in Tr 14. The analysis of the SEDs suggests the presence of transitional discs in which a large amount of gas is still present and sustains accretion onto the PMS object at ages older than 10 Myr. Our results, discussed in light of recent recent discoveries with Herschel of transitional discs containing a massive gas component around the relatively old PMS stars TW Hydrae, 49 Ceti, and HD 95086, support a new scenario n which old and evolved debris discs still host a significant amount of gas.openBeccari, G.; De Marchi, G.; Panagia, N.; Valenti, E.; Carraro, G.; Romaniello, M.; Zoccali, M.; Weidner, C.Beccari, G.; De Marchi, G.; Panagia, N.; Valenti, E.; Carraro, Giovanni; Romaniello, M.; Zoccali, M.; Weidner, C

Comparing profitability of Burlina and Holstein Friesian cattle breeds

Aim of this study was to compare profitability of Burlina and Holstein Friesian cows in northern Italy. Cow's profitability was calculated for each breed, with consideration of economic incentive programs and alternative milk pricing scenarios. The difference in annual profitability between Burlina and Holstein Friesian ranged from −€719 to −€274 per cow per year. In a low-input management level with a cow's incentive payment and a specific cheese market strategy the low milk yield of Burlina can be compensate respect to Holstein Friesian

Genetic characterization of local Italian breeds of chickens undergoing in situ conservation

The objectives of this study were to determine genetic variation and to analyze population structure of 6 Italian local chicken breeds involved in a conservation program. Twenty microsatellite markers were investigated in 337 birds belonging to 6 breeds: Ermellinata di Rovigo, Robusta Maculata, Robusta Lionata, Pepoi, Padovana, and Polverara; a commercial layer cross was used as reference. One hundred twelve alleles were detected in the overall population, with a mean number of 5.6 +/- 2.1 alleles per locus. For the local breeds, the observed and expected heterozygosity ranged from a minimum of 0.240 to a maximum of 0.413 and from 0.243 to 0.463 for the Pepoi and Polverara breeds, respectively. Deviation from Hardy-Weinberg equilibrium was observed in 5 breeds and in the commercial cross. The overall population heterozygote deficiency was 0.427, the average inbreeding coefficient was 0.097, and the heterozygote deficiency due to breed subdivisions was 0.437. Reynolds' distances were used to draw an unrooted neighbor-joining tree, which topology gave information on the genetic origin of these breeds and confirmed their known history. The estimated molecular kinship within a breed ranged from 0.559 to 0.769, evidencing high coancestry. Structure analysis was performed to detect the presence of population substructures. Inferred clusters corresponded to the different breeds, without presence of admixture. The exception was the Polverara breed, for which a more complex genetic structure was found. The results supported the decision of safeguarding these breeds as an important reservoir of genetic diversity and confirmed the usefulness of microsatellite markers to characterize and to monitor genetic variability in local chicken breeds

genetic variation and population structure of italian native sheep breeds undergoing in situ conservation

The genetic variability and presence of population substructures in 4 native Northern Italian sheep breeds, Alpagota, Brogna, Foza, and Lamon, un- dergoing in situ conservation, and 1 widespread Italian breed, Bergamasca, were studied by investigating 19 microsatellite markers. The breeds showed considerable genetic variability in terms of number of alleles and heterozygosity, with the exception of Alpagota, which was the least variable (0.607). Nevertheless, a signifi- cant deficit of heterozygotes was observed in each breed due to rather increased levels of inbreeding or to the presence of population substructures, probably caused by increased genetic variation in the founder popula- tions. The analyses evidenced clear genetic differentia- tion (FST = 0.085), reduced levels of admixture, and presence of private alleles among the breeds, confirm- ing their genetic uniqueness. In particular, according to Reynolds genetic distances, Alpagota was the most differentiated, perhaps because it had been bred mostly in a rather isolated area. Loss of any of the investi- gated breeds would result in a loss of genetic diversity ranging from 0.5 to 1.6% of the total observed gene diversity. Results supported the decision to safeguard these breeds as important reservoirs of genetic diver- sity and suggested breeding and mating practices to maintain variability and to overcome within-breed sub- structures

Eficiência e viabilidade econômica da aplicação de fungicidas no controle da ferrugem asiática da soja em Campo Grande, MS.

Objetivou-se avaliar a eficiência e a viabilidade econômica da aplicação de fungicidas no controle da ferrugem asiática da soja, Phakopsora packyrhizi, em Campo Grande, MS. O ensaio foi conduzido em na safra 2007-2008. Foram avaliados os fungicidas (g i.a./ha): picoxistrobina + ciproconazole (40 + 16, 50 + 20 e 60 + 24) + nimbus 0,25% (v/v), piraclostrobina + epoxiconazole (66,5 + 25); azoxistrobina + ciproconazole (60 + 24) + nimbus 0,25% (v/v); trifloxistrobina + tebuconazole (50 + 100) + auero 0,13% (v/v) e trifloxistrobina + ciproconazole (56,25 + 24) + aureo 0,13% (v/v). Três aplicações foram realizadas, quinzenalmente, a partir do estádio fenológico R2. Foram realizadas 10 avaliações da severidade da doença (terços inferior e superior da planta) e três da desfolha (a partir do estádio R7), com intervalos de sete dias. Após plotagem das curvas de progresso (CP), foram calculadas as áreas abaixo das CP para a severidade da doença (AACPD) e desfolha (AACPDes). Ao final do ensaio, avaliou-se o rendimento de grãos (Rend - kg/ha), a massa de 1.000 grãos (MMG - g) e a viabilidade econômica do controle da doença. O clima durante a condução do ensaio foi favorável ao desenvolvimento da ferrugem asiática, constatando-se relação positiva entre a precipitação e a severidade da doença. Todos os fungicidas apresentaram valores de AACPD inferiores ao da testemunha, com destaque para picoxistrobina + ciproconazole (maior dose). Esse tratamento também apresentou o menor índice de AACPDes. Os fungicidas apresentaram índices semelhantes de Rend, embora superiores à testemunha. Quanto a MMG, maior índice foi atribuído a azoxistrobina + ciproconazole. A mistura trifloxistrobina + tebuconazole apresentou a menor eficiência de controle da ferrugem asiática. Com base na severidade da doença, rendimento de grãos e nos benefícios econômico gerados pela aplicação de fungicidas, identificou-se os fungicidas picoxistrobina + ciproconazole (60 + 24), azoxistrobina + ciproconazole e trifloxistrobina + ciproconazole como os mais promissores para o controle de P. packyrhizi

The Evolution of Globular Clusters in the Galaxy

We investigate the evolution of globular clusters using N-body calculations and anisotropic Fokker-Planck (FP) calculations. The models include a mass spectrum, mass loss due to stellar evolution, and the tidal field of the parent galaxy. Recent N-body calculations have revealed a serious discrepancy between the results of N-body calculations and isotropic FP calculations. The main reason for the discrepancy is an oversimplified treatment of the tidal field employed in the isotropic FP models. In this paper we perform a series of calculations with anisotropic FP models with a better treatment of the tidal boundary and compare these with N-body calculations. The new tidal boundary condition in our FP model includes one free parameter. We find that a single value of this parameter gives satisfactory agreement between the N-body and FP models over a wide range of initial conditions. Using the improved FP model, we carry out an extensive survey of the evolution of globular clusters over a wide range of initial conditions varying the slope of the mass function, the central concentration, and the relaxation time. The evolution of clusters is followed up to the moment of core collapse or the disruption of the clusters in the tidal field of the parent galaxy. In general, our model clusters, calculated with the anisotropic FP model with the improved treatment for the tidal boundary, live longer than isotropic models. The difference in the lifetime between the isotropic and anisotropic models is particularly large when the effect of mass loss via stellar evolution is rather significant. On the other hand the difference is small for relaxation- dominated clusters which initially have steep mass functions and high central concentrations.Comment: 36 pages, 11 figures, LaTeX; added figures and tables; accepted by Ap