2,313 research outputs found
Five day mission plan to investigate the geology of the Marius Hills region of the moon
Five-day mission plan to investigate geology of Marius Hills region of moo
The Optical Polarization Properties of X-ray Selected BL Lacertae Objects
We discuss the optical polarization properties of X-ray selected BL Lacertae
objects (XSBLs) as determined from three years of monitoring 37 BL Lac objects
and candidates. The observed objects include a complete X-ray flux limited
sample drawn from the EMS Survey. The majority of the XSBLs classi- fied solely
on the appearance of their spectra are members of the class of BL~Lacs since
they possess intrinsically polarized and variable continua. The duty cycle of
polarized emission from XSBLs is 40\%. The majority of XSBLs (\%)
have preferred polarization position angles on time scales as long as three
years. This reflects stability in the geometry of the region emitting the
polarized optical emission. We discuss the observed spectral dependence of the
degree of polarization and some of the possible mechanisms for producing the
observed characteristics. While dilution of the polarized emission by the host
galaxy starlight is present in some objects, we demon- strate that the average
polarization properties derived from our observations are not drastically
affected by this effect. The objects in our monitored sample did not display
the larger than one magnitude variations generally used to characterize the
optical variability of blazars in general.Comment: LaTex file, 21 pages, with tables appended as a poscript file.
Contact [email protected] for postscript figure files. Institute for Advanced
Study number AST 93/4
Distant radio galaxies in the near IR
We are carrying out a program of near IR imaging and spectroscopy of radio galaxies with redshifts of 1.5 and greater. One of its principal goals is to constrain the ages and star formation histories of massive galaxies at early epochs. The radio galaxies are drawn from the survey of 1Jy class sources by McCarthy et al (1989) and McCarthy (1990). The sample contains 18 radio galaxies with redshifts greater than 2 and an additional 10 objects with 1.5 less than z less than 2.0. The redshifts were obtained from long slit spectra with the CTIO 4 m. While the galaxies are quite faint (r approximately = 21-24.5) all have Lyman alpha emission with rest frame equivalent widths of 100 - 1000 A. Multicolor photometry in the g,r,i and J,H,K bands has been obtained with the 2.5-m Du Pont Telescope on Las Campanas and with the Hale 5 m telescope at Palomar. We have recently obtained near IR spectra, using the 4 m telescopes at KPNO and CTIO, of a few objects with the goal of determining the Lyman alpha/H-alpha ratio and hence the reddening
Study Protocol for Investigating Physician Communication Behaviours that Link Physician Implicit Racial Bias and Patient Outcomes in Black Patients with Type 2 Diabetes Using an Exploratory Sequential Mixed Methods Design
Introduction Patient-physician racial discordance is associated with Black patient reports of dissatisfaction and mistrust, which in turn are associated with poor adherence to treatment recommendations and underutilisation of healthcare. Research further has shown that patient dissatisfaction and mistrust are magnified particularly when physicians hold high levels of implicit racial bias. This suggests that physician implicit racial bias manifests in their communication behaviours during medical interactions. The overall goal of this research is to identify physician communication behaviours that link physician implicit racial bias and Black patient immediate (patient-reported satisfaction and trust) and long-term outcomes (eg, medication adherence, self-management and healthcare utilisation) as well as clinical indicators of diabetes control (eg, blood pressure, HbA1c and history of diabetes complication). Methods and analysis Using an exploratory sequential mixed methods research design, we will collect data from approximately 30 family medicine physicians and 300 Black patients with type 2 diabetes mellitus. The data sources will include one physician survey, three patient surveys, medical interaction videos, video elicitation interviews and medical chart reviews. Physician implicit racial bias will be assessed with the physician survey, and patient outcomes will be assessed with the patient surveys and medical chart reviews. In video elicitation interviews, a subset of patients (approximately 20–40) will watch their own interactions while being monitored physiologically to identify evocative physician behaviours. Information from the interview will determine which physician communication behaviours will be coded from medical interactions videos. Coding will be done independently by two trained coders. A series of statistical analyses (zero-order correlations, partial correlations, regressions) will be conducted to identify physician behaviours that are associated significantly with both physician implicit racial bias and patient outcomes
Pyramidal Cells in Prefrontal Cortex of Primates: Marked Differences in Neuronal Structure Among Species
The most ubiquitous neuron in the cerebral cortex, the pyramidal cell, is characterized by markedly different dendritic structure among different cortical areas. The complex pyramidal cell phenotype in granular prefrontal cortex (gPFC) of higher primates endows specific biophysical properties and patterns of connectivity, which differ from those in other cortical regions. However, within the gPFC, data have been sampled from only a select few cortical areas. The gPFC of species such as human and macaque monkey includes more than 10 cortical areas. It remains unknown as to what degree pyramidal cell structure may vary among these cortical areas. Here we undertook a survey of pyramidal cells in the dorsolateral, medial, and orbital gPFC of cercopithecid primates. We found marked heterogeneity in pyramidal cell structure within and between these regions. Moreover, trends for gradients in neuronal complexity varied among species. As the structure of neurons determines their computational abilities, memory storage capacity and connectivity, we propose that these specializations in the pyramidal cell phenotype are an important determinant of species-specific executive cortical functions in primates
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