Tunable asymmetric reflectance in silver films near the percolation threshold

We report on the optical characterization of semicontinuous nanostructured silver films exhibiting tunable optical reflectance asymmetries. The films are obtained using a multi-step process, where a nanocrystalline silver film is first chemically deposited on a glass substrate and then subsequently coated with additional silver via thermal vacuum-deposition. The resulting films exhibit reflectance asymmetries whose dispersions may be tuned both in sign and in magnitude, as well as a universal, tunable spectral crossover point. We obtain a correlation between the optical response and charge transport in these films, with the spectral crossover point indicating the onset of charge percolation. Such broadband, dispersion-tunable asymmetric reflectors may find uses in future light-harvesting systems.Comment: 18 pages, 5 figures, accepted by Journal of Applied Physic

Ethical Concerns in the Business of Recreation and Leisure

Recreation professionals entering the world of business confront value conflicts and ethical dilemmas. Ethical decision-making traditionally has been guided by philosophical principles briefly outlined in this article. Some professionals find the classical approaches too abstract for dealing with the very concrete-situations of the business world. Others accuse classical ethical theory of a utopian, even anticapitalistic, bias. A number of business situations with potential value conflicts are described, including competition, truth in advertising; relations with employees, and relation with clients/customers. An anticipatory ethical approach is recommended, with business administrators providing ethical leadership at the policy level, and the individual recreation entrepreneur recognizing the responsibility to develop a personal framework for resolving ethical dilemmas in a reasoned and consistent way

Overshoots in stress strain curves: Colloid experiments and schematic mode coupling theory

The stress versus strain curves in dense colloidal dispersions under start-up shear flow are investigated combining experiments on model core-shell microgels, computer simulations of hard disk mixtures, and mode coupling theory. In dense fluid and glassy states, the transient stresses exhibit first a linear increase with the accumulated strain, then a maximum ('stress overshoot') for strain values around 5%, before finally approaching the stationary value, which makes up the flow curve. These phenomena arise in well-equilibrated systems and for homogeneous flows, indicating that they are generic phenomena of the shear-driven transient structural relaxation. Microscopic mode coupling theory (generalized to flowing states by integration through the transients) derives them from the transient stress correlations, which first exhibit a plateau (corresponding to the solid-like elastic shear modulus) at intermediate times, and then negative stress correlations during the final decay. We introduce and validate a schematic model within mode coupling theory which captures all of these phenomena and handily can be used to jointly analyse linear and large-amplitude moduli, flow curves, and stress-strain curves. This is done by introducing a new strain- and time-dependent vertex into the relation between the the generalized shear modulus and the transient density correlator.Comment: 21 pages, 13 figure

Detection of gravitational-wave bursts with chirplet-like template families

Gravitational Wave (GW) burst detection algorithms typically rely on the hypothesis that the burst signal is "locally stationary", that is it changes slowly with frequency. Under this assumption, the signal can be decomposed into a small number of wavelets with constant frequency. This justifies the use of a family of sine-Gaussian templates in the Omega pipeline, one of the algorithms used in LIGO-Virgo burst searches. However there are plausible scenarios where the burst frequency evolves rapidly, such as in the merger phase of a binary black hole and/or neutron star coalescence. In those cases, the local stationarity of sine-Gaussians induces performance losses, due to the mismatch between the template and the actual signal. We propose an extension of the Omega pipeline based on chirplet-like templates. Chirplets incorporate an additional parameter, the chirp rate, to control the frequency variation. In this paper, we show that the Omega pipeline can easily be extended to include a chirplet template bank. We illustrate the method on a simulated data set, with a family of phenomenological binary black-hole coalescence waveforms embedded into Gaussian LIGO/Virgo-like noise. Chirplet-like templates result in an enhancement of the measured signal-to-noise ratio.Comment: 8 pages, 6 figures. Submitted to Class. Quantum Grav. Special issue: Proceedings of GWDAW-14, Rome (Italy), 2010; fixed several minor issue

Clinically important differences in the intensity of chronic refractory breathlessness

Context: Clinically important differences in chronic refractory breathlessness are ill defined but important in clinical practice and trial design. Objectives: To estimate the clinical relevance of differences in breathlessness intensity using distribution and patient anchor methods. Methods: This was a retrospective data analysis from 213 datasets from four clinical trials for refractory breathlessness. Linear regression was used to explore the relationship between study effect size and change in breathlessness score (0-100 mm visual analogue scale) and to estimate the change in score equivalent to small, moderate, and large effect sizes. Pooled individual blinded patient preference data from three randomized controlled trials were analyzed. The difference between the mean change in Day 4 minus baseline scores between preferred and non-preferred arms was calculated. Results: There was a strong relationship between change in score and effect size (P = 0.001; R 2 = 0.98). Values for small, moderate, and large effects were -5.5, -11.3, and -18.2 mm. The participant preference change in score was -9 mm (95% CI, -15.8, -2.1) (P = 0.008). Conclusion: This larger dataset supports a clinically important difference of 10 mm. Studies should be powered to detect this difference

The rabbit as an animal model for the study of ovulation-inducing factor

Ovulation–inducing factor (OIF) is a seminal plasma protein that has been found in the ejaculate of different species. Evidence suggests that OIF and its function may be conserved among species. Our general objective was to develop a rabbit model for the study of OIF in seminal plasma. In the first study, we conducted two experiments to validate the use of ultrasound biomicroscopy as a method for assessing ovarian structures in rabbits, and to develop a method that permits serial noninvasive repetitive ultrasound evaluation of ovarian structures in vivo in rabbits. In Experiment 1, the number and size of follicles ≥ 0.6 mm and corpora lutea (CL) detected by ultrasound biomicroscopy (UBM) ex situ were correlated with those detected by histology in each pair of ovaries from 4 female New Zealand White rabbits (5-5.5 months old) given an ovulation-inducing treatment. In Experiment 2, we translocated the ovaries of female New Zealand white rabbits (n=12; 5 months old) to a subcutaneous position in order to develop a method that permits serial UBM evaluation of ovarian structures in vivo in rabbits. Results showed strong correlations (P < 0.05) between UBM and histology in all the ovarian variables evaluated in Experiment 1, and also showed that ovarian structures are easily identified using UBM in vivo in the rabbits submitted to the surgical approach performed in Experiment 2. In the second study, we conducted two experiments to test the hypothesis that llama and rabbit seminal plasma elicits a surge of LH release and is responsible for inducing ovulation in rabbits. In Experiment 1, we compared the effect of an intramuscular administration of saline, GnRH, llama or rabbit seminal plasma in female New Zealand White rabbits (n=4-6 per group, 5.5 months old) that were group-housed. In Experiment 2, we compared the effects of the same treatments in rabbits (n=5-7 per group, 5.5 months old) that were individually caged. Ovulation and CL formation occurred in most rabbits regardless of the treatment given when animals were group housed, while rabbits given similar treatment but individually housed did not ovulate. In the GnRH group, a surge in plasma LH concentrations was observed in all the rabbits, followed by CL formation and an increase in plasma progesterone concentrations. In summary, we developed a rabbit model for the study of OIF, where ovarian structures can be evaluated in vivo by UBM. Results did not support the hypothesis that OIF in seminal plasma elicits ovulation in rabbits. Further studies are needed to determine the effects of dose and route of administration of seminal plasma in rabbits