Stable flies sense and behaviorally respond to the polarization of light

Insects use their polarization-sensitive photoreceptors in a variety of ecological contexts including host-foraging. Here, we investigated the effect of polarized light on host foraging by the blood-feeding stable fly, Stomoxys calcitrans, a pest of livestock. Electroretinogram recordings with chromatic adaptation demonstrated that the spectral sensitivity of stable flies resembles that of other calyptrate flies. Histological studies of the flies' compound eye revealed differences in microvillar arrangement of ommatidial types, assumed to be pale and yellow, with the yellow R7 and pale R8 photoreceptors having the greatest polarization sensitivity. In behavioural experiments, stable flies preferred to alight on horizontally polarized stimuli with a high degree of linear polarization. This preferential response disappeared when either ultraviolet (UV) or human-visible wavelengths were omitted from light stimuli. Removing specific wavelength bands further revealed that the combination of UV (330-400 nm) and blue (400-525 nm) wavelength bands was sufficient to enable polarized light discrimination by flies. These findings enhance our understanding of polarization vision and foraging behavior among hematophagous insects and should inform future trap designs.

Thermal Disorder in Finite-Length Carbon Nanowire

Enhancement in chemisorption is one of the active research areas in carbon materials. To remedy the thermally degraded chemisorption occurring at high temperatures, we report a comprehensive study of kink structures in free-standing monoatomic carbon nanowires upon heating. Our Monte Carlo simulation considers multi-monoatomic carbon chains laterally interacting by van der Waals forces. Our study reveals that carbon nanowires maintain their linearity regardless of chain length at low temperatures, but this is not the case at high temperatures. Disordered kink structure is observed in short carbon chains, especially above the Peierls transition temperature. A severe kink structure may increase the possibility of attaching negatively charged atoms, thereby contributing to the development of next-generation materials for chemisorption at high temperatures. We have also provided an important indication that any physical property of the finite-length carbon chain predicted by ab initio calculation should reconsider the atomic rearrangement due to thermal instability at high temperatures.

The relationship between maternal pre-pregnancy body mass index and exclusive breastfeeding initiation: Findings from an Australian obstetric cohort

BACKGROUND

To assess the type of infant nutrition at initiation of first feed in association with increasing maternal pre-pregnancy Body Mass Index in an Australian obstetric population.

METHODS

A retrospective cohort study from 2008 to 2013 was undertaken. Body Mass Index was available for 12,347 women categorised into groups according to: underweight (≤18 kg/m²); normal weight (19-24 kg/m²); overweight (25-29 kg/m²); obese class I (30-34 kg/m²); obese class II (35-39/kg²) and obese class III (40+ kg/m²). Type and initiation of infant feeding is routinely recorded in the study hospital's birthing outcomes system. Six body mass index categories and mode of infant feeding were examined using logistic regression. Confounding factors that were controlled for included smoking status, parity, country of birth and maternal age.

RESULTS

Within this cohort, 609 (4.93%) women were underweight, 6235 (50.50%) had a normal BMI, 3116 (25.24%) were overweight, 1314 (10.64%) were obese class I, 596 (4.83%) were obese class II and 477 (3.86%) were obese class III. In adjusted models', as BMI rose, women were significantly less likely to initiate exclusive breastfeeding and more likely to exclusively formula feed. Women with a BMI of 40+ kg/m² had an AOR of 2.91(CI 1.94-4.25) for initiating exclusive formula at the time of their infant's first feed.

CONCLUSIONS

Women who are overweight or obese are significantly less likely to initiate exclusive breastfeeding and more likely to give exclusive formula at the time of their newborn infants first feed. Effective breastfeeding interventions are required for these high-risk groups in the days leading up to and within the first hours after birth.

Control of the ductile and brittle behavior of titanium alloys in diamond cutting by applying a magnetic field

As a result of extensive investigations into deformation mechanisms of titanium alloys, it has been found that ductile and brittle behavior occurs during diamond cutting of the alloys. Other than implementing ductile regime machining for improving machining performances, in this study, an application of magnetic field in diamond cutting is proposed to enhance the machining performances in both ductile and brittle deformations in diamond cutting of titanium alloys. Results from the experiments showed that under the influence of a magnetic field, the cutting heat at the tool/titanium interface decreased, and surface damages induced from the brittle deformation were remarkably suppressed. The surface quality of both ductile and brittle deformation areas was enhanced in a presence of the magnetic field, which the surface profiles were less distortive with fewer cracks and defects in brittle deformation regions, and the cutting forces at the transition point became less fluctuant and much smoother. This study contributes enhancements of machining performances in ductile and brittle machining in diamond cutting of titanium alloys, increasing the precise level of machined components made with titanium alloys.

Ductile and brittle transition behavior of titanium alloys in ultra-precision machining

Titanium alloys are extensively applied in biomedical industries due to their excellent material properties. However, they are recognized as difficult to cut materials due to their low thermal conductivity, which induces a complexity to their deformation mechanisms and restricts precise productions. This paper presents a new observation about the removal regime of titanium alloys. The experimental results, including the chip formation, thrust force signal and surface profile, showed that there was a critical cutting distance to achieve better surface integrity of machined surface. The machined areas with better surface roughness were located before the clear transition point, defining as the ductile to brittle transition. The machined area at the brittle region displayed the fracture deformation which showed cracks on the surface edge. The relationship between depth of cut and the ductile to brittle transaction behavior of titanium alloys in ultra-precision machining(UPM) was also revealed in this study, it showed that the ductile to brittle transaction behavior of titanium alloys occurred mainly at relatively small depth of cut. The study firstly defines the ductile to brittle transition behavior of titanium alloys in UPM, contributing the information of ductile machining as an optimal machining condition for precise productions of titanium alloys.

Use of EBSD to study electropulsing induced reverse phase transformations in a Zn-Al alloy (ZA22)

Multi-phase identification and phase transformations in electropulsing treated Zn-Al based alloy wire specimens were studied using electron back-scattered diffraction, back-scattered scanning electron microscopy and X-ray diffraction techniques. By using electron back-scattered diffraction, two phases: η'(S) and η'(T) with a small difference of about 1% in lattice parameters (c(0)/a(0) ) were identified, based on the determined lattice parameters of the phases, and the reverse eutectoid phase transformations: η'(T) +ɛ'(T) +α'(T) →η'(S) and ɛ+α→T'+η were successfully detected. Electron back-scattered diffraction appeared to be an effective technique for studying complex electropulsing induced phase transformations.

Epigenetic Control of Estrogen Synthesis in Human Preadipocytes and Breast Cancer Cells

Estrogen plays a significant role in the development and progression of breast cancer (BC). Cytochrome aromatase p450, encoded by the gene CYP19, is the key enzyme catalyzing the synthesis of estrogens from androgens. In post-menopausal women, adipose tissue becomes the major site for estrogen production and an increase in CYP19 expression in mammary adipose is strongly linked to the hormone-dependent progression of BC. Therefore, understanding CYP19 regulation in BC is critical for the development of therapeutic measures. Previous studies of CYP19 regulation in BC have mainly focussed on hormone-induced regulation of transcription via upstream tissue- and promoter-specific regulatory regions. While this is clearly important, it is increasingly evident that epigenetic regulation of expression, such as DNA methylation, is also a common factor in the progression of cancers. The aim of this study was to investigate whether CYP19 expression is under epigenetic regulation and to determine if such mechanisms contribute to the tissue- and promoter-specific expression of CYP19 observed in BC.CYP19 transcripts in cancer-free primary human breast adipose fibroblasts (BAFs) stimulated with cytokines and glucocorticoids (e.g. TNFα and dexamethasone) are derived from the distal promoter 1.4, whereas breast tumour-derived factors (e.g. prostaglandin E2) induce a regulatory switch to proximal promoters 1.3 and II. DNA from BAFs maintained under these two conditions was treated with sodium bisulfite allowing for methylation analysis of CpG dinucleotides. Methylation mapping revealed a stochastic heterogeneous level of methylation among 9 CpG sites (promoter 1.4) and 11 CpG sites (promoters 1.3 and II) in untreated BAFs.No correlation was observed between promoter methylation and promoter activation after response to stimuli. However, treatment of BAFs with 5-aza-2'-deoxycytidine, a DNA methylation inhibitor, increased total CYP19 mRNA expression up to 40-fold, primarily via promoter 1.4 thorugh up-regulation of trans-acting factors, suggesting CYP19 is under tonic inhibition by methylation in BAFs. Similar results were also obtained in four BC cell lines. Ongoing work has elucidated trans-acting factors of CYP19 epigenetically silenced in BAFs. These studies uncover a new layer of complexity in the regulation of aromatase expression in BC and may identify new targets for epigenetic therapy, including DNA methylation inhibitors. These findings will translate to BC by determining the methylation state of CYP19 in clinical BC specimens, and by correlation with clinicopathological parameters such as steroid receptor status, grade and stage.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 1147.

Use of EBSD to identify phases in interdendrite region of a cast Zn-Al-based alloy (ZA27)

Electron backscattered Kikuchi diffraction methodology was used to identify phases in the interdendrite region of an alloy ZA27. Two Zn-rich hexagonal close-packed structure phases eta and epsilon phases were distinguished using predetermined lattice parameters of the phases. In relation to studies of scanning electron microscopy and X-ray diffraction, electron backscattered diffraction results revealed that the Al-rich precipitates of the alpha phase were from decomposition of the eta'(T), and the four-phase transformation: alpha+epsilon--> T'+eta, had occurred in the epsilon phase after ageing at 150 degrees C for 8 h.