Growth of single and multilayer sesquioxide crystal films for lasing applications via pulsed laser deposition

Sesquioxides, materials of the form RE2O3 (RE: rare earth), are of great interest for lasing applications. These materials offer high thermal conductivities, are mechanically stable, can easily be doped with various rare earth ions and are optically isotropic. Members of the sesquioxide family have the same crystal structure but differing refractive indices, and hence are ideal candidates for multilayer as well as single film growth. Sesquioxides can be challenging to grow from the melt, however, due to their high melting points (>2400 °C)

Imaging Pulsed Laser Deposition oxide growth by in-situ Atomic Force Microscopy

To visualize the topography of thin oxide films during growth, thereby enabling to study its growth behavior quasi real-time, we have designed and integrated an atomic force microscope (AFM) in a pulsed laser deposition (PLD) vacuum setup. The AFM scanner and PLD target are integrated in a single support frame, combined with a fast sample transfer method, such that in-situ microscopy can be utilized after subsequent deposition pulses. The in-situ microscope can be operated from room temperature (RT) up to 700$^\circ$C and at (process) pressures ranging from the vacuum base pressure of 10$^{-6}$ mbar up to 1 mbar, typical PLD conditions for the growth of oxide films. The performance of this instrument is demonstrated by resolving unit cell height surface steps and surface topography under typical oxide PLD growth conditions.Comment: 8 pages, 8 figure

Spatiotemporal variability in Swedish lake ecosystems

Studying ecosystem dynamics is critical to monitoring and managing linked systems of humans and nature. Due to the growth of tools and techniques for collecting data, information on the condition of these systems is more widely available. While there are a variety of approaches for mining and assessing data, there is a need for methods to detect latent characteristics in ecosystems linked to temporal and spatial patterns of change. Resiliencebased approaches have been effective at not only identifying environmental change but also providing warning in advance of critical transitions in social-ecological systems (SES). In this study, we examine the usefulness of one such method, Fisher Information (FI) for spatiotemporal analysis. FI is used to assess patterns in data and has been established as an effective tool for capturing complex system dynamics to include regimes and regime shifts. We employed FI to assess the biophysical condition of eighty-five Swedish lakes from 1996–2018. Results showed that FI captured spatiotemporal changes in the Swedish lakes and identified distinct spatial patterns above and below the Limes Norrlandicus, a hard ecotone boundary which separates northern and southern ecoregions in Sweden. Further, it revealed that spatial variance changed approaching this boundary. Our results demonstrate the utility of this resilience-based approach for spatiotemporal and spatial regimes analyses linked to monitoring and managing critical watersheds and waterbodies impacted by accelerating environmental change

Characterisation of the porous structure of Gilsocarbon graphite using pycnometry, cyclic porosimetry and void-network modeling

file: :C$$:/pdf/1-s2.0-S000862231400164X-main.pdf:pdfThe cores of the fourteen Advanced Gas-cooled nuclear Reactors (AGRs) within the UK comprise Gilsocarbon graphite, a manufactured material surrounded predominantly by CO2 at high pressure and temperature to provide heat exchange. The intense ionising radiation within the reactors causes radiolytic oxidation, and the resulting mass loss is a primary factor in determining reactor lifetime. The void structure of the porous Gilsocarbon graphite affects the permeability and diffusion of the carbon dioxide, and the sites of oxidation. To model this void structure, the porosities and densities of ten virgin Gilsocarbon graphite samples have been measured by powder and helium pycnometry. For comparison, results are also presented for highly ordered pyrolytic graphite (HOPG), and a fine-grained Ringsdorff graphite. Samples have been examined at a range of magnifications by electron microscopy. Total porosities and percolation characteristics have been measured by standard and cyclic mercury porosimetry up to an applied mercury pressure of 400MPa. Inverse modelling of the cyclic intrusion curves produces simulated void structures with characteristics which closely match those of experiment. Void size distributions of the structures are presented, together with much Supplementary Information. The simulated void networks provide the bases for future simulations of the radiolytic oxidation process itself

Apparatus to control and visualize the impact of a high-energy laser pulse on a liquid target

We present an experimental apparatus to control and visualize the response of a liquid target to a laser-induced vaporization. We use a millimeter-sized drop as target and present two liquid-dye solutions that allow a variation of the absorption coefficient of the laser light in the drop by seven orders of magnitude. The excitation source is a Q-switched Nd:YAG laser at its frequency-doubled wavelength emitting nanosecond pulses with energy densities above the local vaporization threshold. The absorption of the laser energy leads to a large-scale liquid motion at timescales that are separated by several orders of magnitude, which we spatiotemporally resolve by a combination of ultra-high-speed and stroboscopic high-resolution imaging in two orthogonal views. Surprisingly, the large-scale liquid motion at upon laser impact is completely controlled by the spatial energy distribution obtained by a precise beam-shaping technique. The apparatus demonstrates the potential for accurate and quantitative studies of laser-matter interactions.Comment: Submitted to Review of Scientific Instrument

Spatiotemporal variability in Swedish lake ecosystems

Studying ecosystem dynamics is critical to monitoring and managing linked systems of humans and nature. Due to the growth of tools and techniques for collecting data, information on the condition of these systems is more widely available. While there are a variety of approaches for mining and assessing data, there is a need for methods to detect latent characteristics in ecosystems linked to temporal and spatial patterns of change. Resilience-based approaches have been effective at not only identifying environmental change but also providing warning in advance of critical transitions in social-ecological systems (SES). In this study, we examine the usefulness of one such method, Fisher Information (FI) for spatiotemporal analysis. FI is used to assess patterns in data and has been established as an effective tool for capturing complex system dynamics to include regimes and regime shifts. We employed FI to assess the biophysical condition of eighty-five Swedish lakes from 1996-2018. Results showed that FI captured spatiotemporal changes in the Swedish lakes and identified distinct spatial patterns above and below the Limes Norrlandicus, a hard ecotone boundary which separates northern and southern ecoregions in Sweden. Further, it revealed that spatial variance changed approaching this boundary. Our results demonstrate the utility of this resilience-based approach for spatiotemporal and spatial regimes analyses linked to monitoring and managing critical watersheds and waterbodies impacted by accelerating environmental change

Working Hours, Sleep, and Burnout Among Athletic Trainers Employed in College Athletics: A Cross-Sectional Study

Purpose: Burnout continues to be an important concern for athletic trainers working in the collegiate sport setting. The purpose of the study was to examine the relationships between working hours, sleep, and burnout among athletic trainers providing patient care in the collegiate setting. Methods: A web-based (Qualtrics, Provo, UT) cross-sectional study using a self-reported questionnaire was used to collect demographics and data on working hours, sleep, and burnout. The Copenhagen Burnout Inventory (CBI) was used to determine burnout. Results: The mean age of our participants (n=1006) was 33 ∓ 9 years; 37.6% (n=378) were male, 61.5% (619), and 1.1% (n=9) chose not to identify. Participants reported moderate burnout (61.55 ± 12.59) on the CBI, additionally a mean score of 66.41 (± 13.42) on the personal-related subscale, 63.91 (± 13.35) on the work-related subscale, and 53.94 (± 19.75) on the client-related subscale. Working more than 50 hours per a week caused collegiate athletic trainers to experience higher levels of personal and work-related burnout (67.34 (± 13.30) and 64.86 (± 13.64) respectively) as compared to those who worked less than 49 hours per week (63.54 (± 13.40) and 60.95 (± 11.96) respectively). Participants report an average of 6.77 (± .95) hours of sleep per night. Those who report less than 6.9 hours of sleep per night scored a mean of 70.48 (± 13.58) on the personal-related subscale, whereas those who report more than 7 hours of sleep per night scored a mean of 63.97 (± 12.71). Conclusions: Overall, athletic trainers in the collegiate setting are experiencing moderate levels of burnout. Athletic trainers who worked over 40 hours a week and slept less than 7 hours per night had higher levels of burnout. Sleep is an important factor in recovery and likely a strategy to prevent burnout

Ultraviolet writing of channel waveguides in proton-exchanged LiNbO₃

We report on a direct ultraviolet (UV) writing method for the fabrication of channel waveguides at 1.55 µm in LiNbO3 through UV irradiation of surface and buried planar waveguides made by annealed proton exchange and reverse proton exchange. A systematic study of the guidance properties as a function of the UV writing conditions is presented