Meta-analysis of relationship between weaning age and daily weight gain of piglets in the farrowing and nursery phases

A systematic review of the literature was carried out to perform a meta-analysis to assess effects of age at weaning on the performance of piglets in the range of 14 to 42 days old. This step consisted in defining the databases and keywords to be employed in searching for papers for the meta-analysis. To that end, the databases Capes Publication Portal and Google Scholar were searched for researches published from 2001 to 2019. After the acceptance and exclusion criteria had been defined and applied, 28 papers were selected. The data were collected with Excel® software of Microsoft Office for later statistical analysis. Orthogonal polynomial contrasts were used and the linear and quadratic regression equations were fitted with hypotheses tested at the 5% significance level. The results confirmed the disadvantages of early weaning and the benefits of weaning at around 28 days old. In the farrowing phase, piglets weaned after 35 days had lower daily weight gain (DWG) (P =0.002) than those weaned at 27 days. The derivative of the regression of DWG while nursing on age revealed that a weaning age of 26.34 days yielded the maximum DWG among the ages assessed. After weaning, the maximum DWG was achieved by weaning piglets at 32.26 days. Given the performance of piglets in the farrowing and nursery phases, the results of this meta-analysis indicated the best weaning age was between 26 and 32 days

The DNA electronic specific heat at low temperature: The role of aperiodicity

AbstractThe electronic specific heat spectra at constant volume (CV) of a long-range correlated extended ladder model, mimicking a DNA molecule, is theoretically analyzed for a stacked array of a double-stranded structure made up from the nucleotides guanine G, adenine A, cytosine C and thymine T. The role of the aperiodicity on CV is discussed, considering two different nucleotide arrangements with increasing disorder, namely the Fibonacci and the Rudin–Shapiro quasiperiodic structures. Comparisons are made for different values of the band fillings, considering also a finite segment of natural DNA, as part of the human chromosome Ch22

Tidal Dwarf Galaxies at Intermediate Redshifts

We present the first attempt at measuring the production rate of tidal dwarf galaxies (TDGs) and estimating their contribution to the overall dwarf population. Using HST/ACS deep imaging data from GOODS and GEMS surveys in conjunction with photometric redshifts from COMBO-17 survey, we performed a morphological analysis for a sample of merging/interacting galaxies in the Extended Chandra Deep Field South and identified tidal dwarf candidates in the rest-frame optical bands. We estimated a production rate about 1.4 {\times} 10^{-5} per Gyr per comoving volume for long-lived TDGs with stellar mass 3 {\times} 10^{8-9} solar mass at 0.5<z<1.1. Together with galaxy merger rates and TDG survival rate from the literature, our results suggest that only a marginal fraction (less than 10%) of dwarf galaxies in the local universe could be tidally-originated. TDGs in our sample are on average bluer than their host galaxies in the optical. Stellar population modelling of optical to near-infrared spectral energy distributions (SEDs) for two TDGs favors a burst component with age 400/200 Myr and stellar mass 40%/26% of the total, indicating that a young stellar population newly formed in TDGs. This is consistent with the episodic star formation histories found for nearby TDGs.Comment: 9 pages, 5 figures, Accepted for publication in Astrophysics & Space Scienc