Waveguide Fabrication In UV-Photocurable Sol–Gel Materials: Influence Of The Photoinitiating System

In this paper we identify and explain the different chemical interactions involved between a sol–gel matrix and photoinitiators used in the fabrication of optical waveguides. A well-established sol–gel matrix composed of 3-methacryloxypropyltrimethoxysilane, zirconium n-propoxide and methacrylic acid was developed, and two different photoinitiators (Irgacure® 819 and 1800) were added to the host matrix. Optical microscopy was used to characterise the structure of the waveguides as a function of the photoinitiator nature and concentration, and aging of the hybrid sol–gel material. It is clearly demonstrated that the width of the waveguides is strongly influenced by the sol aging. Furthermore, it is shown that degradation of photoinitiators occurs during the sol–gel process. Oxidation of the phosphonyl groups by the zirconium complex accounts for this results

Influence of the bias-voltage on the anchoring energy for nematic liquid crystals

The influence of the bias-voltage on the anisotropic part of the nematic surface energy is analyzed. The experimental data show a strong dependence of the anchoring strength on the bias-voltage when the electrodes of the nematic cell are covered with WO3. The observed dependence can be interpreted taking into account the ions dissolved in the liquid crystal. We propose a model in which the effect of the bias-voltage is to collect the ions near the electrodes, in a surface layer whose thickness is of the order of the Debye’s screening length. The surplus of electric field due to this ions confinement gives rise to an electrostatic contribution to the total energy that can be considered as a surface energy. The proposed model is in good agreement with the experimental data. The model is used to interpret the observed independence of the anchoring strength on the bias-voltage when the indium-oxide electrode is covered with a film of polyimide, or it is without any covering. The influence of a charge emission from the electrodes under the bias voltage on the anchoring energy is also analyzed. Possible applications of the observed phenomenon are discussed

Does undertaking rural placements add to place of origin as a predictor of where health graduates work?

Objective: To determine the work location (metropolitan, regional, rural and remote) of graduates in nursing, allied health and oral health disciplines who complete their professional training, end-to-end training, in a regional or rural area noting the potential inclusion of a metropolitan-based placement for speciality practice not available in rural or regional Victoria. Methods: We tracked the place of employment from the Australian Health Practitioners Regulation Agency (AHPRA) of all graduates from a regional/rural tertiary education provider. The student home address at enrolment, locations where they undertook all placements and their current place of work were described using an objective geographical model of access, the Modified Monash Model. Results: Seventy-five per cent of 5506 graduates were located in the AHPRA database. About one third of graduates were working in metropolitan areas, 1/3 in regional cities and 1/3 in rural areas. Students' origin accounted for 1/3 of variance in current workplace location. The more placement days students completed in regional/ rural areas was also a significant predictor of working in a regional or rural area. Conclusion: End-to-end training in regional/rural areas is an effective approach to retaining a regional/rural workforce. Student origin is a strong predictor of working rural or regionally, as is undertaking placements in rural areas. This suggests that priority for rural/ regional student placements should be given to students in end-to-end regional/ rural programs and students from a regional/ rural background

Spontaneous Learning of Visual Structures in Domestic Chicks

Effective communication crucially depends on the ability to produce and recognize structured signals, as apparent in language and birdsong. Although it is not clear to what extent similar syntactic-like abilities can be identified in other animals, recently we reported that domestic chicks can learn abstract visual patterns and the statistical structure defined by a temporal sequence of visual shapes. However, little is known about chicks’ ability to process spatial/positional information from visual configurations. Here, we used filial imprinting as an unsupervised learning mechanism to study spontaneous encoding of the structure of a configuration of different shapes. After being exposed to a triplet of shapes (ABC or CAB), chicks could discriminate those triplets from a permutation of the same shapes in different order (CAB or ABC), revealing a sensitivity to the spatial arrangement of the elements. When tested with a fragment taken from the imprinting triplet that followed the familiar adjacency-relationships (AB or BC) vs. one in which the shapes maintained their position with respect to the stimulus edges (AC), chicks revealed a preference for the configuration with familiar edge elements, showing an edge bias previously found only with temporal sequences

Young domestic chicks spontaneously represent the absence of objects

Absence is a notion that is usually captured by language-related concepts like zero or negation. Whether nonlinguistic creatures encode similar thoughts is an open question, as everyday behavior marked by absence (of food, of social partners) can be explained solely by expecting presence somewhere else. We investigated 8-day-old chicks' looking behavior in response to events violating expectations about the presence or absence of an object. We found different behavioral responses to violations of presence and absence, suggesting distinct underlying mechanisms. Importantly, chicks displayed an avian signature of novelty detection to violations of absence, namely a sex-dependent left-eye-bias. Follow-up experiments excluded accounts that would explain this bias by perceptual mismatch or by representing the object at different locations. These results suggest that the ability to spontaneously form representations about the absence of objects likely belongs to the initial cognitive repertoire of vertebrate species

Noxious stimulation induces self-protective behavior in bumblebees

It has been widely stated that insects do not show self-protective behavior towards noxiously-stimulated body parts, but this claim has never been empirically tested. Here, we tested whether an insect species displays a type of self-protective behavior: self-grooming a noxiously-stimulated site. We touched bumblebees (Bombus terrestris) on the antenna with a noxiously-heated (65°C) probe and found that, in the first two minutes after this stimulus, bees groomed their touched antenna more than their untouched antenna and more than bees that were touched with an unheated probe or not touched at all. Our results present evidence that bumblebees display self-protective behavior. We discuss the potential neural mechanisms of this behavior and the implications for the topic of insect pain