Building a community of practice to address alcohol harms in Canada: Experience from the Canadian Alcohol Policy Evaluation project.

Setting: Alcohol is a major cause of health and social costs and harms in Canada. While research and awareness of harms caused by alcohol are on the rise, few transdisciplinary platforms exist that are committed to facilitating bold alcohol policy change to reduce health inequities and improve lives.

Intervention: In response to feedback heard during engagement for the Canadian Alcohol Policy Evaluation project, an alcohol policy-focused community of practice (CoP) was launched in January 2022.

Polyglutamine-expanded ATXN7 alters a specific epigenetic signature underlying photoreceptor identity gene expression in SCA7 mouse retinopathy.

Background: Spinocerebellar ataxia type 7 (SCA7) is a neurodegenerative disorder that primarily affects the cerebellum and retina. SCA7 is caused by a polyglutamine expansion in the ATXN7 protein, a subunit of the transcriptional coactivator SAGA that acetylates histone H3 to deposit narrow H3K9ac mark at DNA regulatory elements of active genes. Defective histone acetylation has been presented as a possible cause for gene deregulation in SCA7 mouse models.

Gene Deregulation and Underlying Mechanisms in Spinocerebellar Ataxias With Polyglutamine Expansion.

Polyglutamine spinocerebellar ataxias (polyQ SCAs) include SCA1, SCA2, SCA3, SCA6, SCA7, and SCA17 and constitute a group of adult onset neurodegenerative disorders caused by the expansion of a CAG repeat sequence located within the coding region of specific genes, which translates into polyglutamine tract in the corresponding proteins. PolyQ SCAs are characterized by degeneration of the cerebellum and its associated structures and lead to progressive ataxia and other diverse symptoms. In recent years, gene and epigenetic deregulations have been shown to play a critical role in the pathogenesis of polyQ SCAs.

Laser beam diffraction at the edge of a film and application to thin film metrology.

The thickness change of a film is measured optically using self-interference of a single laser beam incident at the edge of the film. Theory suggests that when a half-plane phase shift is applied to a Gaussian laser beam, interference fringes appear in the near and far field, in which position varies with the amount of phase shift. By measuring fringe pattern displacement, we demonstrate detection of thickness changes in chitosan films induced by temperature rises of a few degrees centigrade.

Mid-IR laser beam quality measurement through vanadium dioxide optical switching.

We present a beam characterization system for infrared lasers which can measure both wavefront and beam profile with visible detectors. While previous studies demonstrated the conversion from the visible to the near infrared, this device exploits the wavelength conversion from the infrared to the visible, which is based on the refractive index change because of the optical switching of a vanadium dioxide layer. This technique can be applied over a broad spectral range from the visible to the infrared and potentially to the terahertz.

Continuously variable, electrically addressed beam splitter based on vanadium dioxide.

Vanadium dioxide (VO(2)) is used to implement an electrically addressable beam splitter with continuously variable splitting ratios. The electrical control of temperature in a thin VO(2) layer is used to vary its transmission/reflection behavior. The technique is characterized for various incidence angles, s- and p-polarizations, and the wavelength range of 400-2000 nm.

Surface heating by optical beams and application to mid-infrared imaging.

Heating of surfaces by optical beams is investigated theoretically and compared with experimental results in the context of infrared imaging with vanadium dioxide thin films. Using known solutions for the diffusion of point heat sources at the interface between two semi-infinite media, the theory is extended to beams of Gaussian and flat profiles, for steady-state and dynamic regimes. Parameters relevant to imaging, such as spatial resolution and response time, are linked to thermal diffusivity, beam dimensions, and intensity.

Single laser beam measurement of thermal diffusivity.

Thermal diffusion properties of interfaces are measured using self-induced surface thermal lensing with a single laser beam. The time evolution of the reflected beam reveals information on heat diffusion away from the interface. Unambiguous correlation between measured signal and thermal diffusivity is shown, theoretically and experimentally, from which calibration curves are obtained.

Observation of discrete surface solitons.

We report the first observation of discrete optical surface solitons at the interface between a nonlinear self-focusing waveguide lattice and a continuous medium. The effect of power on the localization process of these optical self-trapped states at the edge of an AlGaAs waveguide array is investigated in detail. Our experimental results are in good agreement with theoretical predictions.

Discrete surface solitons.

It is theoretically shown that discrete nonlinear surface waves are possible in waveguide lattices. These self-trapped states are located at the edge of the array and can exist only above a certain power threshold. The excitation characteristics and stability properties of these surface waves are systematically investigated.

Effect of protein : energy ratio in milk replacers on growth performance of goat kids.

Two separate experiments were carried out to establish the effects of the protein:energy ratio in milk replacers on growth performance, plasma lipid concentrations and fatty acid composition in adipose tissue of male goat kids. In the first experiment there were 211 3-day- old goat kids and in the second experiment there were 121 kids aged 3-7 days. The animals were fed ad libitum for a period of 4 weeks on milk replacers containing either 11.

Time evolution of reflective thermal lenses and measurement of thermal diffusivity in bulk solids.

A simple method for optically measuring the thermal diffusivity of solids is demonstrated. The thermal displacement created on a substrate by a focused laser beam is determined from the divergence that it induces in a weak probe beam. The dynamics of the surface lens and the amplitude of the probe beam's divergence are then used to determine the thermal diffusivity of the substrate.

Passive system with tunable group velocity for propagating electrical pulses from sub- to superluminal velocities.

We report an observation of tunable group velocity from sub-luminal to superluminal in a completely passive system. Electric pulses are sent along a spatially periodic conducting medium containing a punctual nonlinearity, and the resulting amplitude-dependent phase shift allows us to control dispersion and the propagation velocity at the stop band frequency.

Anomalous dispersion and superluminal group velocity in a coaxial photonic crystal: theory and experiment.

We demonstrate that coaxial cables with a periodic impedance exhibit dispersion properties specific to photonic crystals, albeit on a much lower frequency scale. Highly superluminal (>2c) pulse propagation is observed near the photonic band gap at 10 MHz. The influence of group velocity dispersion and crystal length on the traveling speed and shape of a Gaussian pulse are discussed.

Generation of high-repetition-rate femtosecond pulses from 8 to 18 microm.

We generated subpicosecond pulses from 8 to 18 mum by difference-frequency mixing in a 1-mm-thick AgGaSe(2) crystal, the 130- and 180-fs output pulses (1.45 < lambda < 1.85 mum) from an 84-MHz-repetition-rate optical parametric oscillator.

A structural model for the interaction of haem with unsaturated fatty acids explaining its quasi-lipoxygenase activity. Quantum chemical calculations.

The quasi-lipoxygenase activity of haemoglobin differs in many respects from the well-known haemin-catalyzed lipid peroxidation (1-4), especially in its high substrate specificity for unsaturated fatty acids containing one 1,4-pentadiene system (dienoic fatty acids). In this report a structural model for the fatty acid haem interaction based on quantum-chemical calculations is presented which show that only dienoic fatty acids are bound to the haem in such a way that the initial hydrogen abstraction that is necessary for the over-all reaction, is favoured sterically and energetically.