Electromagnetic shielding with polypyrrole-coated fabrics

Several shielding applications, to protect human health and electronic devices against dangerous effects of electromagnetic radiation, require solutions that fabrics can suitably fulfill. Here, we will investigate the electromagnetic interference shielding effectiveness of polypyrrole-coated polyester textiles, in the frequency range 100-1000 MHz. Insertion losses for several conductive fabrics with different surface resistivity ranging from 40 Ohm till the very low value of 3 Ohm were evaluated with a dual-tem cell. Correlations between the shielding effectiveness and the conductivity of composites are also discussed.Comment: 6 pages, 6 figure

Meta-análise de parâmetros genéticos relacionados ao consumo alimentar residual e a suas características componentes em bovinos

O objetivo deste trabalho foi estimar, por meio de meta-análise, a herdabilidade (h²) e as correlações genética (r g) e fenotípica (r f) do consumo alimentar residual (CAR), e das suas características componentes, em bovinos de 19 raças ou grupamentos genéticos. Foram utilizados 22 trabalhos científicos publicados entre 1963 e 2011, de oito países, o que totalizou 52.637 bovinos com idades que variaram de 28 dias até a idade de abate. As estimativas de CAR, consumo de matéria seca (CMS), ganho médio diário (GMD) e peso metabólico (PV0, 75) foram ponderadas pelo inverso da variância amostral. A variação da h² de cada característica entre os estudos foi analisada por quadrados mínimos ponderados. Os efeitos de sexo, país e raça foram significativos para h² de CAR e explicaram 67% da variação entre os estudos. Para CMS, os efeitos de país e raça foram significativos e explicaram 96% da variação. As estimativas combinadas de h² foram: 0, 255±0, 008, 0, 278±0, 012, 0, 321±0, 015 e 0, 397±0, 032 para CAR, CMS, GMD e PV0, 75, respectivamente. As estimativas combinadas de correlação genética e fenotípica foram baixas entre CAR e GMD e entre CAR e PV0, 75 (de -0, 021±0, 034 a 0, 025±0, 035), e de média magnitude entre CAR e CMS (0, 636±0, 035 a 0, 698±0, 041) e entre CMS, GMD e PV0, 75 (0, 441±0, 062 a 0, 688±0, 032). O CAR apresenta estimativa de herdabilidade menor que a de suas características componentes

Correlations of visual scores, carcass traits, feed efficiency and retail product yield in Nellore cattle

The growing use of visual scores (VS) and ultrasound (US) for carcass evaluation in breeding programs, calls for a knowledge of the relationships between these traits and other relevant characteristics, such as feed efficiency and production of commercial cuts. The objective of this study was to evaluate correlations between body visual scores and carcass traits identified by ultrasound (US) and feed efficiency (FE), carcass weight (HCW), dressing percentage (DP) and retail product yield (RPY) in beef cattle. Nellore cattle (male), 42 non-castrated [NCAST] and 44 castrated [CAST]) were evaluated by both VS and US, at the postweaning (15-month old) and finishing phases (21-month old). Visual scores of conformation (C), precocity (P) and muscling (M) were assessed and the backfat thickness (UBFT), rump fat thickness (URFT) and ribeye area (UREA) were measured by ultrasound. Gain-to-feed (G:F) ratio and residual feed intake (RFI) were measured in feedlot. Hot carcass weight, DP and RPY were determined at harvest. Non-castrated cattle had greater HCW and RPY but lower UBFT and URFT than CAST. Postweaning VS and US were poorly correlated with FE in both sexual conditions. Finishing VS were negatively correlated with G:F in CAST and finishing URFT was negatively correlated with RPY in NCAST. The relationship of VS and US with feed efficiency and meat yield is affected by age at the date of evaluation and by castration. Feed efficiency is not related to the yield of meat cuts in Nellore cattl