Optical Maser Emission from Trivalent Praseodymium in Calcium Tungstate

Coherent emission at 1.047 µ from trivalent praseodymium in calcium tungstate was observed. This emission coincides with strong infrared fluorescence at the same wavelength and was found to be stimulated mostly by absorption of blue light by the 3P0, 3P1, and 3P2 bands. The emission corresponds to a 1G4-->3H4 transition with the terminal level 377 cm^–1 from the ground state. The oscillation threshold was the same at 4.2°, 20°, and 78°K. No stimulated emission was observed at room temperature. The lifetime of the metastable state 1G4 is 50×10^–3 sec. A new technique used to measure the lifetime is described

Curvature Effects and Flow Uniformity Optimization of a Blood Microchannel

An important field of study in microfluidics is in the realm of blood rheology in microdevices. Many types of geometries have been developed for different lab-on-chip applications for sampling and analysis. The majority of experimental and numerical studies have revolved around straight blood vessel geometries, but in recent years there have been more complex profiles analyzed, such as microbifurcations. Some devices are developed to study blood flow similar to the microvascular network, such as diverging and converging bifurcations to study arterioles, which form a closed network. Cell adhesion studies of microchannels are also common, where symmetric bifurcation and confluence has been examined. Since sharp turns as well as bifurcation and confluence are common, the hemodynamics should be examined for many different shapes and the effects of channel geometry to the adhesion phenomena should be looked at. Different devices have different goals, such as isolating circulating tumor cells from blood, separating leukocytes from blood and isolating circulating tumor cells from peripheral blood. Studies have been targeted in breast cancer, cervical cancer and smooth muscle cell applications. Some studies provide result as to the role that the hemodynamic forces have on the recruitment of the metastatic cancer cells to endothelial cells, but the effects of device geometry on adhesion isn’t typically discussed formally. It has been shown that more complex geometries exhibit more non-uniform cell adhesion, adding to the confusion in the results and that an improvement in the velocity uniformity has been shown to improve the uniformity of the cell adhesion in sharp turn devices

Materials Design using Correlated Oxides: Optical Properties of Vanadium Dioxide

Materials with strong electronic Coulomb interactions play an increasing role in modern materials applications. "Thermochromic" systems, which exhibit thermally induced changes in their optical response, provide a particularly interesting case. The optical switching associated with the metal-insulator transition of vanadium dioxide (VO2), for example, has been proposed for use in "intelligent" windows, which selectively filter radiative heat in hot weather conditions. In this work, we develop the theoretical tools for describing such a behavior. Using a novel scheme for the calculation of the optical conductivity of correlated materials, we obtain quantitative agreement with experiments for both phases of VO2. On the example of an optimized energy-saving window setup, we further demonstrate that theoretical materials design has now come into reach, even for the particularly challenging class of correlated electron systems.Comment: 4+x pages, 2 figure

The role of gamut, intuition and engagement in colour management in a design context

Colour management is ubiquitous in the digital world. However, despite the many advances in colour management over the last couple of decades, it remains an imperfect process. In the art and design community there is often a level of dissatisfaction and deep cynicism about colour management that can lead to lac of engagement with the process. This research explores colour management in a design context though three issues: the gamut issue, the intuitive issue and the engagement issue; each relates to areas where colour management could better connect with tacit design knowhow. The work focusses on the selection of colour in a digital context since for many users this is the first touch point that they have with colour management. Psychophysical studies have been carried out in both laboratory and design‐studio settings. It is shown that users can better predict the results from subtractive colour mixing than from additive colour mixing. The performance of various types of colour picker are explored and consequences for the design of user interfaces are discussed

Fractal Dimensions in Perceptual Color Space: A Comparison Study Using Jackson Pollock's Art

The fractal dimensions of color-specific paint patterns in various Jackson Pollock paintings are calculated using a filtering process which models perceptual response to color differences (\Lab color space). The advantage of the \Lab space filtering method over traditional RGB spaces is that the former is a perceptually-uniform (metric) space, leading to a more consistent definition of ``perceptually different'' colors. It is determined that the RGB filtering method underestimates the perceived fractal dimension of lighter colored patterns but not of darker ones, if the same selection criteria is applied to each. Implications of the findings to Fechner's 'Principle of the Aesthetic Middle' and Berlyne's work on perception of complexity are discussed.Comment: 21 pp LaTeX; two postscript figure

The intervention process in the European Fans in Training (EuroFIT) trial: a mixed method protocol for evaluation

Background - EuroFIT is a gender-sensitised, health and lifestyle program targeting physical activity, sedentary time and dietary behaviours in men. The delivery of the program in football clubs, led by the clubs’ community coaches, is designed to both attract and engage men in lifestyle change through an interest in football or loyalty to the club they support. The EuroFIT program will be evaluated in a multicentre pragmatic randomised controlled trial (RCT), for which ~1000 overweight men, aged 30–65 years, will be recruited in 15 top professional football clubs in the Netherlands, Norway, Portugal and the UK. The process evaluation is designed to investigate how implementation within the RCT is achieved in the various football clubs and countries and the processes through which EuroFIT affects outcomes. Methods - This mixed methods evaluation is guided by the Medical Research Council (MRC) guidance for conducting process evaluations of complex interventions. Data will be collected in the intervention arm of the EuroFIT trial through: participant questionnaires (n = 500); attendance sheets and coach logs (n = 360); observations of sessions (n = 30); coach questionnaires (n = 30); usage logs from a novel device for self-monitoring physical activity and non-sedentary behaviour (SitFIT); an app-based game to promote social support for physical activity outside program sessions (MatchFIT); interviews with coaches (n = 15); football club representatives (n = 15); and focus groups with participants (n = 30). Written standard operating procedures are used to ensure quality and consistency in data collection and analysis across the participating countries. Data will be analysed thematically within datasets and overall synthesis of findings will address the processes through which the program is implemented in various countries and clubs and through which it affects outcomes, with careful attention to the context of the football club. Discussion - The process evaluation will provide a comprehensive account of what was necessary to implement the EuroFIT program in professional football clubs within a trial setting and how outcomes were affected by the program. This will allow us to re-appraise the program’s conceptual base, optimise the program for post-trial implementation and roll out, and offer suggestions for the development and implementation of future initiatives to promote health and wellbeing through professional sports clubs. Trial Registration - ISRCTN81935608. Registered on 16 June 2015

Facile control of silica nanoparticles using a novel solvent varying method for the fabrication of artificial opal photonic crystals

In this work, the Stöber process was applied to produce uniform silica nanoparticles (SNPs) in the meso-scale size range. The novel aspect of this work was to control the produced silica particle size by only varying the volume of the solvent ethanol used, whilst fixing the other reaction conditions. Using this one-step Stöber-based solvent varying (SV) method, seven batches of SNPs with target diameters ranging from 70 to 400 nm were repeatedly reproduced, and the size distribution in terms of the polydispersity index (PDI) was well maintained (within 0.1). An exponential equation was used to fit the relationship between the particle diameter and ethanol volume. This equation allows the prediction of the amount of ethanol required in order to produce particles of any target diameter within this size range. In addition, it was found that the reaction was completed in approximately 2 h for all batches regardless of the volume of ethanol. Structurally coloured artificial opal photonic crystals (PCs) were fabricated from the prepared SNPs by self-assembly under gravity sedimentation

A New, Bright, Short-Period, Emission Line Binary in Ophiuchus

The 11th magnitude star LS IV -08 3 has been classified previously as an OB star in the Luminous Stars survey, or alternatively as a hot subdwarf. It is actually a binary star. We present spectroscopy, spectroscopic orbital elements, and time series photometry, from observations made at the Kitt Peak National Observatory 2.1m, Steward Observatory 2.3m, MDM Observatory 1.3m and 2.4m, Hobby-Eberly 9.2m, and Michigan State University 0.6m telescopes. The star exhibits emission of varying strength in the cores of H and He I absorption lines. Emission is also present at 4686 Angstroms (He II) and near 4640/4650 Angstroms (N III/C III). Time-series spectroscopy collected from 2005 July to 2007 June shows coherent, periodic radial velocity variations of the H-alpha line, which we interpret as orbital motion with a period of 0.1952894(10) days. High-resolution spectra show that there are two emission components, one broad and one narrow, moving in antiphase, as might arise from an accretion disk and the irradiated face of the mass donor star. Less coherent, low-amplitude photometric variability is also present on a timescale similar to the orbital period. Diffuse interstellar bands indicate considerable reddening, which however is consistent with a distance of ~100-200 pc. The star is the likely counterpart of a weak ROSAT X-ray source, whose properties are consistent with accretion in a cataclysmic variable (CV) binary system. We classify LS IV -08 3 as a new member of the UX UMa subclass of CV stars.Comment: To be published in AJ, 16 pages, 6 figures. Uses AAS Late