Bianchi I model as a prototype for a cyclical Universe

We analyze the dynamics of the Bianchi I model in the presence of stiff matter, an ultrarelativistic component and a small negative cosmological constant. We quantize this model in the framework of the polymer quantum mechanics, in order to introduce cut-off features in the minisuperspace dynamics. We then apply to the polymer Wheeler-DeWitt equation, emerging from the Dirac constraint, an adiabatic approximation a la Vilenkin, which treats the Universe volume as a quasi-classical variable, becoming de facto the dynamical clock for the pure quantum degrees of freedom, here identified in the Universe anisotropies. The main issue of the present analysis consists of determining a cyclical evolution for the Bianchi I model, oscillating between the Big-Bounce induced by the cut-off physics and the turning point due to the small cosmological constant. Furthermore, the mean value of the Universe anisotropy variables remains finite during the whole evolution, including the phase across the Big-Bounce. Such a feature, according to a suitable choice of the initial conditions makes the present cosmological paradigm, a viable scenario for the description of a possible primordial and late phases of the actual Universe.Comment: 12 pages, 6 figure

A Survey on Feedlot Performance of Purebred and Crossbred European Young Bulls and Heifers Managed Under Intensive Conditions in Veneto, Northeast Italy

This study, based on a nearly 10-year collection of performance data of young bulls and beef heifers, aimed to benchmark production traits of specialized fattening herds of northern Italy and to compare the performance of stock calves belonging to several European genetic types (GT). Data originated from 2806 batches (a group of stock calves homogeneous for GT, origin, finishing herd, fattening period, and diets), and concerned 188,891 animals of 10 GT herded in 44 farms of the Veneto region. For each batch, average body weight (BW) at arrival and at sale, duration of the fattening period, losses due to injury or death, purchase and sell price were collected, and average daily gain (ADG) and net sale gain (NSG) per head, per day of fattening, and per kg of BW gain were computed. Charolais and Limousine young bulls accounted for nearly 50% and 20%, respectively, of all animals, and over 90% of calves originated from France. Average BW at arrival and at slaughter approximated 370 and 650 kg, respectively, and ADG approached 1.30 kg/d, but variation due to GT was large (P<0.01). Charolais young bulls were the heaviest at slaughter and showed the greatest ADG, whereas Irish crosses produced the highest NSG per head and per day of fattening. Year affected all traits (P<0.01), but his magnitude was limited for BW at purchase or sale and for ADG, and slightly larger for NSG, even if this last trait did not evidence any long period congruent trend

Phenotypic characterisation of major mineral composition predicted by mid-infrared spectroscopy in cow milk

Population-level phenotyping is, for some traits, hardly achievable due to limitation of reference analyses. Mid-infrared spectroscopy (MIRS) is a quick and cost-effective laboratory technique allowing the prediction of innovative milk quality features on a large scale. The present study aimed at investigating factors associated with milk Ca, K, Mg, Na and P contents predicted by MIRS models on a large multi-breed spectral data set of 123,240 test-day records. Two dairy (Holstein–Friesian and Brown Swiss) and two dual-purpose (Simmental and Alpine Grey) cattle breeds were considered. Sources of variation of predicted milk mineral contents were studied using linear mixed models, including the fixed effects of breed, month of sampling, stage of lactation, parity and interactions between the main effects. Random factors were herd nested within breed, cow nested within breed and the residual. Calcium content was greater in milk of dual-purpose than dairy cattle breeds. Simmental cows produced milk with the greatest content of Ca and Na, and milk of Holstein-Friesian had the lowest P content. Variation of content of Ca, Mg, Na and P throughout lactations exhibited an opposite trend to that of milk yield, with the lowest values around the peak of lactation. On the other hand, K content mirrored the trend of milk yield. Multiparous cows had lower content of milk minerals, with the exception of Na, compared with first parity animals. Environmental factors identified in the present study can be considered for within-breed genetic evaluation to adjust records of milk mineral contents for these effects

PIXE characterization of CsI(Tl) scintillators used for particle detection in nuclear reactions

Particle-Induced X-ray Emission has been used to measure Thallium concentration in several CsI(Tl) scintillators from different manufacturers, in order to check their nominal declared values and correlate their behaviour with actual Tl concentration. Indeed, both Tl doping level and its uniformity affect light emission of these detectors, which are largely employed in nuclear physics experiments. In some of the examined crystals Tl concentration values from PIXE measurements came out to be quite different from those declared. This allowed us to explain apparent anomalies in the trend of their a/c-induced light yield ratio versus Tl content. In some cases, the presence of unexpected contaminants was also pointed out. 2008 Elsevier B.V. All rights reserved

Effects of Stearoyl-CoA Desaturase 1 and Sterol Regulatory Element Binding Protein Gene Polymorphisms on Milk Production, Composition and Coagulation Properties of Individual Milk of Brown Swiss Cows

Associations between stearoyl-CoA desaturase (SCD) and sterol regulatory element binding protein (SREBP-1) gene polymorphisms and milk production, composition (fat, protein, and casein content), acidity (pH and titratable acidity) and coagulation properties (MCP), namely rennet coagulation time (RCT, min) and curd firmness (a30, mm) were investigated on individual Brown Swiss milk. A total of 294 cows from 16 herds and progeny of 15 sires were milk-sampled once. Th e additive effects of SCD and SREBP-1 genotypes on the aforementioned traits were analyzed through Bayesian linear models. The SCD gene was associated with protein content, casein content and a30. Lower protein, casein and a30 was observed for milk yielded by SCD V than A cows, whereas for other traits the effect was trivial. Animals carrying the L allele of SREBP-1 showed higher fat content than animals carrying the S allele. These results suggest a possible use of these loci in gene-assisted selection programs for the improvement of milk quality traits and MCP in Brown Swiss cattle, although large scale studies in different breeds are required