Spontaneous formation of macroscopic chiral domains in a fluid smectic phase of achiral molecules

A smectic liquid-crystal phase made from achiral molecules with bent cores was found to have fluid layers that exhibit two spontaneous symmetry-breaking instabilities: polar molecular orientational ordering about the layer normal and molecular tilt. These instabilities combine to form a chiral layer structure with a handedness that depends on the sign of the tilt. The bulk states are either antiferroelectric-racemic, with the layer polar direction and handedness alternating in sign from layer to layer, or antiferroelectric-chiral, which is of uniform layer handedness. Both states exhibit an electric field-induced transition from antiferroelectric to ferroelectric.     

Toll‐like receptor and related cytokine mRNA expression in bovine corpora lutea during the oestrous cycle and pregnancy

Improving our understanding of the mechanisms controlling the corpus luteum (CL) and its role in regulating the reproductive cycle should lead to improvements in the sustainability of today's global animal industry. The corpus luteum (CL) is a transient endocrine organ composed of a heterogeneous mixture steroidogenic, endothelial and immune cells, and it is becoming clear that immune mechanisms play a key role in CL regulation especially in luteolysis. Toll‐like receptors (TLR) mediate innate immune mechanisms via the production of pro‐inflammatory cytokines, especially within various tissues, although the role of TLR within CL remains unknown. Thus, the objectives of this study were to characterize TLR mRNA expression in the CL during the oestrous cycle and in pregnancy (day 30–50), and to examine the role of TLR signalling in luteal cells. Corpora lutea were collected at various stages of the cycle and pregnancy and analysed for TLR and cytokine mRNA expression. In addition, luteal cells were cultured with the TLR4 ligand (lipopolysaccharide, LPS) for 24 h to evaluate the role of TLR4 in regulating luteal function. Toll‐like receptors 1, 2, 4, 6, tumour necrosis factor alpha (TNF), interferon gamma (IFN‐G), and interleukin (IL)‐12, mRNA expressions were greatest in regressing CL compared with earlier stages (p < .05), whereas no change was observed for IL‐6 mRNA expression. Cytokine mRNA expression in cultured luteal cells was not altered by LPS. Based on these data, one or more of the TLRs found within the CL may play a role in luteolysis, perhaps via pro‐inflammatory cytokine mRNA expression.     

Systemic antibacterial drug use in dogs in Australia

A survey of veterinarians' use of antibacterial drugs was conducted by distributing a questionnaire to Australian practitioners. Respondents were asked to indicate their general patterns of use of various systemic antibacterial drugs and drug combinations in dogs and their approach to certain specified clinical disorders. Overall, antibacterials of the p-lactam type (penicillins and cephalosporins) were most commonly used. Other antibacterials with substantial use were doxycycline, sulphonamide-trimethoprim, metronidazole, fluoroquinolones and clindamycin. Drug selection for different disorders was generally appropriate when compared with recommendations in recent texts, although inappropriate use was evident in some circumstances.     

Strong regularities in world wide web surfing

One of the most common modes of accessing information in the World Wide Web is surfing from one document to another along hyperlinks. Several large empirical studies have revealed common patterns of surfing behavior. A model that assumes that users make a sequence of decisions to proceed to another page, continuing as long as the value of the current page exceeds some threshold, yields the probability distribution for the number of pages that a user visits within a given Web site. This model was verified by comparing its predictions with detailed measurements of surfing patterns. The model also explains the observed Zipf-like distributions in page hits observed at Web sites.     

Reconstruction of Current Flow and Imaging of Current-Limiting Defects in Polycrystalline Superconducting Films

Magneto-optical imaging was used to visualize the inhomogeneous penetration of magnetic flux into polycrystalline TlBa2Ca2Cu3Ox films with high critical current densities, to reconstruct the local two-dimensional supercurrent flow patterns and to correlate inhomogeneities in this flow with the local crystallographic misorientation. The films have almost perfect c-axis alignment and considerable local a- and b-axis texture because the grains tend to form colonies with only slightly misaligned a and b axes. Current flows freely over these low-angle grain boundaries but is strongly reduced at intermittent colony boundaries of high misorientation. The local (<10-micrometer scale) critical current density Jc varies widely, being up to 10 times as great as the transport Jc (scale of approximately 1 millimeter), which itself varies by a factor of about 5 in different sections of the film. The combined experiments show that the magnitude of the transport Jc is largely determined by a few high-angle boundaries.     

Efficiency of Two Enucleation Methods Connected to Handmade Cloning to Produce Transgenic Porcine Embryos

The purpose of our work was to establish an efficient-oriented enucleation method to produce transgenic embryos with handmade cloning (HMC). After 41–42 h oocytes maturation, the oocytes were further cultured with or without 0.4 μg/ml demecolcine for 45 min [chemically assisted handmade enucleation (CAHE) group vs polar body (PB) oriented handmade enucleation (OHE) group respectively]. After removal of the cumulus cells and partial digestion of the zona pellucida, oocytes with visible extrusion cones and/or polar bodies attached to the surface were subjected to oriented bisection. Putative cytoplasts without extrusion cones or PB were selected as recipients. Two cytoplasts were electrofused with one transgenic fibroblasts expressing green fluorescent protein (GFP), while non-transgenic fibroblasts were used as controls. Reconstructed embryos were cultured in Well of Wells (WOWs) with porcine zygote medium 3 (PZM-3) after activation. Cleavage and blastocyst rates were registered on day 2 and day 7 of in vitro culture respectively. Meanwhile, the total blastocyst cell number was counted on day 7. We found that the difference was only observed between blastocyst rates (38.6 ± 2% vs 48.1 ± 3%) of cloned embryos with GFP transgenic fibroblast cells after CAHE vs OHE. With adjusted time-lapse for zonae-free cloned embryos cultured in WOWs with PZM-3, it was obvious that in vitro developmental competence after CAHE was compromised when compared with the OHE method. OHE enucleation method seems to be a potential superior alternative method used for somatic cell nuclear transfer (SCNT) with transgenic fibroblast cells.