Origin Of the enhanced flexoelectricity of relaxor ferroelectrics

We have measured the bending-induced polarization of Pb(Mg1/3Nb2/3)O3-PbTiO3 single crystals with compositions at the relaxor-ferroelectric phase boundary. The crystals display very large flexoelectricity, with flexocoupling coefficients an order of magnitude bigger than the theoretical upper limit set by the theories of Kogan and Tagantsev. This enhancement persists in the paraphrase up to a temperature T* that coincides with the start of elastic softening in the crystals. Analysis of the temperature dependence and cross-correlation between flexoelectric, dielectric and elastic properties indicates that the large bendinginduced polarization of relaxor ferroelectrics is not caused by intrinsically giant flexoelectricity, but by the reorientation of polar nanotwins that become ferroelastically active below T*

Genetic structure and diversity of the selfing model grass Brachypodium stacei (Poaceae) in Western Mediterranean: out of the Iberian Peninsula and into the islands

Annual Mediterranean species of the genus Brachypodiurn are promising model plants for energy crops since their selfing nature and short-life cycles are an advantage in breeding programs. The false brome, B. distachyon, has already been sequenced and new genomic initiatives have triggered the de-novo genuine sequencing of its close relatives such as B. stacei, a species that was until recently mistaken for B. distachyon. However, the success of these initiatives hinges on detailed knowledge about the distribution of genetic variation within and among populations for the effective use of germplasm in la breeding program. Understanding population genetic diversity and genetic structure is also an important prerequisite for designing effective experimental populations for genomic wide studies. However, population genetic data are still limited in B. stacei. We therefore selected and amplified 10 nuclear microsatellite markers to depict patterns of population structure and genetic variation 13 among 181 individuals from 19 populations of B. stacei occurring in its predominant range, the western Mediterranean area: mainland Iberian Peninsula, continental Balearic Islands and oceanic Canary Islands. Our genetic results support the occurrence of a predominant selfing system with extremely high levels of homozygosity across the analyzed populations. Despite the low level of genetic variation found, two different genetic clusters were retrieved, one clustering all SE Iberian mainland populations and the island of Minorca and another one grouping all SE Iberian mainland populations, the Canary Islands and all Majorcan populations except one that clustered with the former group. These results, together with a high sharing of alleles (89%) suggest different colonization routes from the mainland Iberian Peninsula into the islands. A recent colonization scenario could explain the relatively low levels of genetic diversity and low number of alleles found in the Canary Islands populations while older colonization events are hypothesized to explain the high genetic diversity values found in the Majorcan populations. Our study provides widely applicable information about geographical patterns of genetic variation in B. stacei. Among others, the genetic pattern and the existence of local alleles will need to be adequately reflected in the germplasm collection of B. stacei for efficient genome wide association studies

Genetic relatedness and taxonomy in closely related species of Hedysarum (Fabaceae)

A multidisciplinary study, engaging morphological, carpological and molecular data, has been performed to investigate the genetic relatedness and taxonomic boundaries of the close species Hedysarum gmelinii, H. setigerum and H. chaiyrakanicum (Fabaceae) with overlapped distribution areas in southern Siberia. The diagnostic features of these legume species are analyzed and discussed, including their macro- and micromorphological characteristics, seed coat ornamentation and inter-simple sequence repeat (ISSR) profiles. The morphometric features, pod and seed microsculpture traits of H. chaiyrakanicum and the ISSR patterns of the three species have been determined for the first time. Sprout, leaf, calyx, corolla, and stem rachis measurements, leaflet indumentum type and ISSR patterns significantly discriminate H. chaiyrakanicum from the other two species, whereas plant height, lengths of stem and leaf, and length and width of leaflet show opposite ranges of variation for H. gmelinii and H. setigerum though none of them is reliable in species identification. Ornamentation of seed coat and ISSR patterns does not differ significantly in the species. Therefore, our study supports the separate taxonomic treatment of H. chaiyrakanicum and the subordination of the cryptic species H. setigerum within H. gmelinii

Análisis de rentabilidad de la inversión en mejoramiento genético de ganado bovino lechero bajo condiciones chilenas

Published by Asociación de Economistas Agrarios de ChileFarm Management, profitability index, genotype-environment interaction, semen price.,

Alternativas e consequências da debicagem em galinhas reprodutoras e poedeiras comerciais.

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Strain gradient induced polarization in SrTiO3 single crystals

Piezoelectricity is inherent only in noncentrosymmetric materials, but a piezoelectric response can also be obtained in centrosymmetric crystals if subjected to inhomogeneous deformation. This phenomenon, known as flexoelectricity, affects the functional properties of insulators, particularly thin films of high permittivity materials. We have measured strain-gradient-induced polarization in single crystals of paraelectric SrTiO$_3$ as a function of temperature and orientation down to and below the 105 K phase transition. Estimates were obtained for all the components of the flexoelectric tensor, and calculations based on these indicate that local polarization around defects in SrTiO$_3$ may exceed the largest ferroelectric polarizations. A sign reversal of the flexoelectric response detected below the phase transition suggests that the ferroelastic domain walls of SrTiO$_3$ may be polar.Comment: 4 pages, 3 figures, 1 tabl

Lesão por pododermatite em frangos de corte alojados em diferentes densidades.

A criação avícola com uma maior densidade visa o aumento da produção, com o mínimo de investimentos em construções e otimização dos custos fixos. Em consequência, a pressão para redução dos custos na criação de frangos de corte levou ao aumento da densidade das aves que promove maior produção de peso vivo/m2 (2). Além disso, a piora na qualidade da cama, principalmente pela compactação decorrente de aumento de umidade, determina o aparecimento de lesões na pele, pododermatites, calo de peito e hematomas (4). As pododermatites de contato são lesões erosivas da pele, predominantes na superfície plantar das patas dos frangos de corte. A etiologia apresenta uma inflamação da pele devido a uma combinação de umidade e fatores cáusticos presentes na cama, sendo a excreta das aves, que é composta de ácido úrico, um agente importante na formação do problema (1). As pododermatites em frangos de corte passaram a ter maior relevância nos últimos anos devido à exportação dos pés dos frangos para os mercados da Ásia. Objetivou-se com este trabalho avaliar o efeito do aumento da densidade em aviário convencional sobre a frequência de lesões por pododermatite em frangos de corte

Efeito da composição da dieta e suplementação com fitase sobre aspectos físicos da tíbia em frangos de corte.

Para avaliar o efeito do farelo de trigo e a suplementação de fitase sobrea resistência óssea, rigidez e flexibilidade da tíbia foram alojados em gaiolas metabólicas 384 pintos de corte, machos da linhagem Cobb, distribuídos em quatro tratamentos em um arranjo fatorial 2x2 em delineamento de blocos casualizados com oito repetições e 12 aves por unidade experimental. Os tratamentos foram: T1 -dieta basal (milho e farelo soja) sem fitase; T2 ?dieta basal com 500 FTU/kg de fitase; T3?20% farelo de trigo, sem fitase; T4 ?20% farelo de trigo, com 500 FTU/kg de fitase. Aos 22 e 32 dias de idade foram abatidas duas aves por unidade experimental para a retirada da tíbia e posterior análise. Aos 22 dias de idade os ossos apresentaram maior rigidez em aves alimentadas com dieta basal com e sem fitase. Maior resistência a quebra e flexibilidade foram encontradas somente para as aves que receberam dieta basal sem fitase. Aos 32 dias de idade as aves que receberam farelo de trigo apresentaram tíbias com maior rigidez que as aves que receberam dieta a base de farelo de soja e milho. To evaluate the effect of wheat meal and phytase supplementation on break strength, flexibility and rigidity of the tibia 384 broiler chicks, Cobb males were housed in metabolic cages and allotted to four treatments in a 2x2 factorial arrangement using a randomized block design with eight replicates of 12 birds per experimental unit. The treatments were: T1 -basal diet (corn and soybean meal without phytase), T2 -basal diet with 500 FTU/kg of phytase), T3 - 20% wheat meal without phytase and T4 - 20% wheat meal with 500 FTU/kg of phytase. At 22 and 32 days of age two birds per experimental unit were slaughtered for the withdrawal of the tibia for subsequent analysis. At 22 days of age, birds fed basal diet with and without phytase showed higher bone stiffness. Greater breaking strength and flexibility were found only for those birds receiving the basal diet without phytate. At 32days of age birds receiving 20% of wheat meal shown greater tibia rigidity than birds fed a corn-soybean meal -based diet