Periodicity-Doubling Cascades: Direct Observation in Ferroelastic Materials.

Very sensitive responses to external forces are found near phase transitions. However, transition dynamics and preequilibrium phenomena are difficult to detect and control. We have observed that the equilibrium domain structure following a phase transition in ferroelectric and ferroelastic BaTiO_{3} is attained by halving of the domain periodicity multiple times. The process is reversible, with periodicity doubling as temperature is increased. This observation is reminiscent of the period-doubling cascades generally observed during bifurcation phenomena, and, thus, it conforms to the "spatial chaos" regime earlier proposed by Jensen and Bak [Phys. Scr. T 9, 64 (1985)PHSTER0281-184710.1088/0031-8949/1985/T9/009] for systems with competing spatial modulations.EPSR

Can the outcome of pelvic-floor rehabilitation in patients with fecal incontinence be predicted?

Purpose: Pelvic-floor rehabilitation does not provide the same degree of relief in all fecal incontinent patients. We aimed at studying prospectively the ability of tests to predict the outcome of pelvic-floor rehabilitation in patients with fecal incontinence. Materials and methods: Two hundred fifty consecutive patients (228 women) underwent medical history and a standardized series of tests, including physical examination, anal manometry, pudendal nerve latency testing, anal sensitivity testing, rectal capacity measurement, defecography, endoanal sonography, and endoanal magnetic resonance imaging. Subsequently, patients were referred for pelvic-floor rehabilitation. Outcome of pelvic-floor rehabilitation was quantified by the Vaizey incontinence score. Linear regression analyses were used to identify candidate predictors and to construct a multivariable prediction model for the posttreatment Vaizey score. Results: After pelvic-floor rehabilitation, the mean baseline Vaizey score (18, SD±3) was reduced with 3.2 points (p<0.001). In addition to the baseline Vaizey score, three elements from medical history were significantly associated with the posttreatment Vaizey score (presence of passive incontinence, thin stool consistency, primary repair of a rupture after vaginal delivery at childbed) (R2, 0.18). Th

A high resolution atlas of gene expression in the domestic sheep (Ovis aries)

Sheep are a key source of meat, milk and fibre for the global livestock sector, and an important biomedical model. Global analysis of gene expression across multiple tissues has aided genome annotation and supported functional annotation of mammalian genes. We present a large-scale RNA-Seq dataset representing all the major organ systems from adult sheep and from several juvenile, neonatal and prenatal developmental time points. The Ovis aries reference genome (Oar v3.1) includes 27,504 genes (20,921 protein coding), of which 25,350 (19,921 protein coding) had detectable expression in at least one tissue in the sheep gene expression atlas dataset. Network-based cluster analysis of this dataset grouped genes according to their expression pattern. The principle of 'guilt by association' was used to infer the function of uncharacterised genes from their co-expression with genes of known function. We describe the overall transcriptional signatures present in the sheep gene expression atlas and assign those signatures, where possible, to specific cell populations or pathways. The findings are related to innate immunity by focusing on clusters with an immune signature, and to the advantages of cross-breeding by examining the patterns of genes exhibiting the greatest expression differences between purebred and crossbred animals. This high-resolution gene expression atlas for sheep is, to our knowledge, the largest transcriptomic dataset from any livestock species to date. It provides a resource to improve the annotation of the current reference genome for sheep, presenting a model transcriptome for ruminants and insight into gene, cell and tissue function at multiple developmental stages

A transmission electron microscopy study of low-strain epitaxial BaTiO3 grown onto NdScO3

Ferroelectric materials exhibit a strong coupling between strain and electrical polarization. In epitaxial thin films, the strain induced by the substrate can be used to tune the domain structure. Substrates of rare-earth scandates are sometimes selected for the growth of ferroelectric oxides because of their close lattice match, which allows the growth of low-strain dislocation-free layers. Transmission electron microscopy (TEM) is a frequently used technique for investigating ferroelectric domains at the nanometer-scale. However, it requires to thin the specimen down to electron transparency, which can modify the strain and the electrostatic boundary conditions. Here, we have investigated a 320 nm thick epitaxial layer of BaTiO3 grown onto an orthorhombic substrate of NdScO3 with interfacial lattice strains of -0.45% and -0.05% along the two in-plane directions. We show that the domain structure of the layer can be significantly altered by TEM sample preparation depending on the orientation and the geometry of the lamella. In the as-grown state, the sample shows an anisotropic a/c ferroelastic domain pattern in the direction of largest strain. If a TEM lamella is cut perpendicular to this direction so that strain is released, a new domain pattern is obtained, which consists of bundles of thin horizontal stripes parallel to the interfaces. These stripe domains correspond to a sheared crystalline structure (orthorhombic or monoclinic) with inclined polarization vectors and with at least four variants of polarization. The stripe domains are distributed in triangular-shaped 180° domains where the average polarization is parallel to the growth direction. The influence of external electric fields on this domain structure was investigated using in situ biasing and dark-field imaging in TEM

A transmission electron microscopy study of low-strain epitaxial BaTiO 3 grown onto NdScO 3

Ferroelectric materials exhibit a strong coupling between strain and electrical polarization. In epitaxial thin films, the strain induced by the substrate can be used to tune the domain structure. Substrates of rare-earth scandates are sometimes selected for the growth of ferroelectric oxides because of their close lattice match, which allows the growth of low-strain dislocation-free layers. Transmission electron microscopy (TEM) is a frequently used technique for investigating ferroelectric domains at the nanometer-scale. However, it requires to thin the specimen down to electron transparency, which can modify the strain and the electrostatic boundary conditions. Here, we have investigated a 320 nm thick epitaxial layer of BaTiO3 grown onto an orthorhombic substrate of NdScO3 with interfacial lattice strains of −0.45% and −0.05% along the two in-plane directions. We show that the domain structure of the layer can be significantly altered by TEM sample preparation depending on the orientation and the geometry of the lamella. In the as-grown state, the sample shows an anisotropic a/c ferroelastic domain pattern in the direction of largest strain. If a TEM lamella is cut perpendicular to this direction so that strain is released, a new domain pattern is obtained, which consists of bundles of thin horizontal stripes parallel to the interfaces. These stripe domains correspond to a sheared crystalline structure (orthorhombic or monoclinic) with inclined polarization vectors and with at least four variants of polarization. The stripe domains are distributed in triangular-shaped 180° domains where the average polarization is parallel to the growth direction. The influence of external electric fields on this domain structure was investigated using in situ biasing and dark-field imaging in TEM

Local deformation gradients in epitaxial Pb(Zr0.2Ti0.8)O-3 layers investigated by transmission electron microscopy

Lead zirconate titanate samples are used for their piezoelectric and ferroelectric properties in various types of micro-devices. Epitaxial layers of tetragonal perovskites have a tendency to relax by forming 90 degrees ferroelastic domains. The accommodation of the a/c/a/c polydomain structure on a flat substrate leads to nanoscale deformation gradients which locally influence the polarization by flexoelectric effect. Here, we investigated the deformation fields in epitaxial layers of Pb(Zr0.2Ti0.8)O-3 grown on SrTiO3 substrates using transmission electron microscopy (TEM). We found that the deformation gradients depend on the domain walls inclination (+45 degrees or -45 degrees to the substrate interface) of the successive 90 degrees domains and we describe three different a/c/a domain configurations: one configuration with parallel a-domains and two configurations with perpendicular a-domains (V-shaped and hat-Lambda-shaped). In the parallel configuration, the c-domains contain horizontal and vertical gradients of out-of-plane deformation. In the V-shaped and hat-Lambda-shaped configurations, the c-domains exhibit a bending deformation field with vertical gradients of in-plane deformation. Each of these configurations is expected to have a different influence on the polarization and so the local properties of the film. The deformation gradients were measured using dark-field electron holography, a TEM technique, which offers a good sensitivity (0.1%) and a large field-of-view (hundreds of nanometers). The measurements are compared with finite element simulations