The Anisoplanatic Point Spread Function in Adaptive Optics

The effects of anisoplanatism on the adaptive optics point spread function are investigated. A model is derived that combines observations of the guide star with an analytic formulation of anisoplanatism to generate predictions for the adaptive optics point spread function at arbitrary locations within the field of view. The analytic formulation captures the dependencies of anisoplanatism on aperture diameter, observing wavelength, angular offset, zenith angle and turbulence profile. The predictions of this model are compared to narrowband 2.12 um and 1.65 um images of a 21 arcsec binary (mV=7.3, 7.6) acquired with the Palomar Adaptive Optics System on the Hale 5 meter telescope. Contemporaneous measurements of the turbulence profile made with a DIMM/MASS unit are used together with images of the primary to predict the point spread function of the binary companion. Predicted companion Strehl ratios are shown to match measurements to within a few percent, whereas predictions based on the isoplanatic angle approximation are highly discrepant. The predicted companion point spread functions are shown to agree with observations to 10%. These predictions are used to measure the differential photometry between binary members to an accuracy of 1 part in 10^{3}, and the differential astrometry to an accuracy of 1 mas. Errors in the differential astrometry are shown to be dominated by differential atmospheric tilt jitter. These results are compared to other techniques that have been employed for photometry, astrometry, and high contrast imaging.Comment: 26 pages, 7 figure

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

Scintillator-based ion beam profiler for diagnosing laser-accelerated ion beams

Next generation intense, short-pulse laser facilities require new high repetition rate diagnostics for the detection of ionizing radiation. We have designed a new scintillator-based ion beam profiler capable of measuring the ion beam transverse profile for a number of discrete energy ranges. The optical response and emission characteristics of four common plastic scintillators has been investigated for a range of proton energies and fluxes. The scintillator light output (for 1 MeV > Ep < 28 MeV) was found to have a non-linear scaling with proton energy but a linear response to incident flux. Initial measurements with a prototype diagnostic have been successful, although further calibration work is required to characterize the total system response and limitations under the high flux, short pulse duration conditions of a typical high intensity laser-plasma interaction

An Adaptation To Life In Acid Through A Novel Mevalonate Pathway.

Extreme acidophiles are capable of growth at pH values near zero. Sustaining life in acidic environments requires extensive adaptations of membranes, proton pumps, and DNA repair mechanisms. Here we describe an adaptation of a core biochemical pathway, the mevalonate pathway, in extreme acidophiles. Two previously known mevalonate pathways involve ATP dependent decarboxylation of either mevalonate 5-phosphate or mevalonate 5-pyrophosphate, in which a single enzyme carries out two essential steps: (1) phosphorylation of the mevalonate moiety at the 3-OH position and (2) subsequent decarboxylation. We now demonstrate that in extreme acidophiles, decarboxylation is carried out by two separate steps: previously identified enzymes generate mevalonate 3,5-bisphosphate and a new decarboxylase we describe here, mevalonate 3,5-bisphosphate decarboxylase, produces isopentenyl phosphate. Why use two enzymes in acidophiles when one enzyme provides both functionalities in all other organisms examined to date? We find that at low pH, the dual function enzyme, mevalonate 5-phosphate decarboxylase is unable to carry out the first phosphorylation step, yet retains its ability to perform decarboxylation. We therefore propose that extreme acidophiles had to replace the dual-purpose enzyme with two specialized enzymes to efficiently produce isoprenoids in extremely acidic environments

Constraining anomalous Higgs interactions

The recently announced Higgs discovery marks the dawn of the direct probing of the electroweak symmetry breaking sector. Sorting out the dynamics responsible for electroweak symmetry breaking now requires probing the Higgs interactions and searching for additional states connected to this sector. In this work we analyze the constraints on Higgs couplings to the standard model gauge bosons using the available data from Tevatron and LHC. We work in a model--independent framework expressing the departure of the Higgs couplings to gauge bosons by dimension--six operators. This allows for independent modifications of its couplings to gluons, photons and weak gauge bosons while still preserving the Standard Model (SM) gauge invariance. Our results indicate that best overall agreement with data is obtained if the cross section of Higgs production via gluon fusion is suppressed with respect to its SM value and the Higgs branching ratio into two photons is enhanced, while keeping the production and decays associated to couplings to weak gauge bosons close to their SM prediction.Comment: v3: Added acknowledgment to FP7 ITN INVISIBLES (Marie Curie Actions PITN-GA-2011-289442). Nothing else changed with respect to v