A dense Bose fluid at zero temperature: condensation and clusters in liquid He-4

We present a full set of wave equations describing a dense Bose fluid, applicable both to non- ideal gases and to liquid 4He. The phonon spectrum in liquid 4He is found and the fraction of condensed particles is calculated at zero temperature for a wide range of densities. The theory also yields the ground-state energy for the quantum liquid 4He in agreement to high accuracy with Monte Carlo simulations and experimental data at low pressure. We also present the derivation of a generalized Hartree-Fock equation describing roton clusters in low temperature liquid 4He, allowing us to confirm that, at low enough temperatures and for a wide range of pressures, the stable clusters consist of 13 bound atoms.Comment: 16 pages, 7 figure

Input-output relations for multiport ring cavities

Quantum input-output relations for a generic $n$-port ring cavity are obtained by modeling the ring as a cascade of $n$ interlinked beam splitters. Cavity response to a beam impinging on one port is studied as a function of the beam-splitter reflectivities and the internal phase-shifts. Interferometric sensitivity and stability are analyzed as a function of the number of ports.Comment: 6 pages, 5 figures (low-res

The Effects of Patient Characteristics on Clinician’s Adherence to Preventive Practice Guidelines

ABSTRACT BACKGROUND: The existence of health disparities confirms that not all patients, regardless of differences in patient demographics, are provided quality healthcare (Agency of Health Care Research and Quality, 2003). Moreover, research suggests that health disparities may be present due to the inadequate delivery of medical services (S. Haist, J. Wilson, M. Lineberry, & C. Griffith, 2007; Van Ryn, Burgess, Malat, & Griffin, 2006). The differences in the delivery of care and services to ethnic minorities and those of low socioeconomic status warrant examining the role healthcare providers play in the causation of these health disparities (Smedley, Stith, & Nelson, 2003). OBJECTIVE: The purpose of the study is to identify differences in routine screening practices of Physician Assistants and determine if such differences are associated with patients’ race and socioeconomic status. DESIGN: One hundred and twelve (N = 112) practicing Physician Assistants (N = 142) in Kentucky were surveyed and randomly assigned to receive one of four clinical vignettes. The likelihood of offering different routine screening recommendations was examined based on patient race and socioeconomic status. MAIN MEASURES: We investigated the mean differences of selected preventative care recommendation options for vignette patients as a function of patient race and socioeconomic status. KEY RESULTS: A multivariate analysis revealed that the race of a patient had a statistically significant multivariate effect on differences in screening recommendation, (p =.017) for hypertension (HTN), p=.017, immunization, p=.002. Univariate analysis showed statistically significant differences, with the African American patient were significantly less likely to receive screening for hypertension (HTN), (M = 3.42), 95% CI [3.24, 3.59], or immunizations (M = 2.45), 95% CI [2.21, 2.69] when compared to Caucasian women (M = 3.71, 2.98), 95% CIs [3.55, 3.88], [2.76, 3.23], respectively. CONCULSION: The findings suggest that the race of the patient in the vignette influenced the likelihood of receiving screening recommendations. The findings show that care delivered by Physician Assistants (PAs), are a possible source of healthcare disparities between patients from racial/ethnic minority backgrounds and their Caucasian counterparts. Keywords: disparities, health education, race & ethnicity, socioeconomic, preventive car

Scanning Electron Microscopy: A Review and Report of Research in Wood Science

Scanning electron microscopy is discussed in light of its principles, advantages, and applications. Comparisons of this system are made with the light microscopic and transmission electron systems. A cross section of pertinent literature on the scanning electron microscope, its development and use, has been integrated into the initial sections to provide a reference base for this general field. A detailed literature view on the use of this system in the field of wood science has also been included.The result of the author's research on wood through use of the scanning electron microscope is reported. Effect of techniques used to prepare specimens for viewing by this method and the effect of the environment inside the microscope itself were determined. A means for preserving original green structure of wood was determined by studying the bordered pit structure in redwood. Finally, 3/8-inch plywood was used in exploring means for improving image contrast at the wood-adhesive interface. Use of much reduced incident electron-beam voltage on uncoated specimens showed promise as a means of studying distribution patterns in wood containing materials of different conductivity

A model of ant route navigation driven by scene familiarity

In this paper we propose a model of visually guided route navigation in ants that captures the known properties of real behaviour whilst retaining mechanistic simplicity and thus biological plausibility. For an ant, the coupling of movement and viewing direction means that a familiar view specifies a familiar direction of movement. Since the views experienced along a habitual route will be more familiar, route navigation can be re-cast as a search for familiar views. This search can be performed with a simple scanning routine, a behaviour that ants have been observed to perform. We test this proposed route navigation strategy in simulation, by learning a series of routes through visually cluttered environments consisting of objects that are only distinguishable as silhouettes against the sky. In the first instance we determine view familiarity by exhaustive comparison with the set of views experienced during training. In further experiments we train an artificial neural network to perform familiarity discrimination using the training views. Our results indicate that, not only is the approach successful, but also that the routes that are learnt show many of the characteristics of the routes of desert ants. As such, we believe the model represents the only detailed and complete model of insect route guidance to date. What is more, the model provides a general demonstration that visually guided routes can be produced with parsimonious mechanisms that do not specify when or what to learn, nor separate routes into sequences of waypoints

The effects of velocities and lensing on moments of the Hubble diagram

We consider the dispersion on the supernova distance-redshift relation due to peculiar velocities and gravitational lensing, and the sensitivity of these effects to the amplitude of the matter power spectrum. We use the MeMo lensing likelihood developed by Quartin, Marra & Amendola (2014), which accounts for the characteristic non-Gaussian distribution caused by lensing magnification with measurements of the first four central moments of the distribution of magnitudes. We build on the MeMo likelihood by including the effects of peculiar velocities directly into the model for the moments. In order to measure the moments from sparse numbers of supernovae, we take a new approach using Kernel Density Estimation to estimate the underlying probability density function of the magnitude residuals. We also describe a bootstrap re-sampling approach to estimate the data covariance matrix. We then apply the method to the Joint Light-curve Analysis (JLA) supernova catalogue. When we impose only that the intrinsic dispersion in magnitudes is independent of redshift, we find $\sigma_8=0.44^{+0.63}_{-0.44}$ at the one standard deviation level, although we note that in tests on simulations, this model tends to overestimate the magnitude of the intrinsic dispersion, and underestimate $\sigma_8$. We note that the degeneracy between intrinsic dispersion and the effects of $\sigma_8$ is more pronounced when lensing and velocity effects are considered simultaneously, due to a cancellation of redshift dependence when both effects are included. Keeping the model of the intrinsic dispersion fixed as a Gaussian distribution of width 0.14 mag, we find $\sigma_8 = 1.07^{+0.50}_{-0.76}$.Comment: 16 pages, updated to match version accepted in MNRA