Chromatic nearest neighbor searching: A query sensitive approach☆☆A preliminary version of this paper appeared in the Proceedings of the 7th Canadian Conference on Computational Geometry, 1995, pp. 261–266.

AbstractThe nearest neighbor problem is that of preprocessing a set P of n data points in Rd so that, given any query point q, the closest point in P to q can be determined efficiently. In the chromatic nearest neighbor problem, each point of P is assigned a color, and the problem is to determine the color of the nearest point to the query point. More generally, given k⩾1, the problem is to determine the color occurring most frequently among the k nearest neighbors. The chromatic version of the nearest neighbor problem is used in many applications in pattern recognition and learning. In this paper we present a simple algorithm for solving the chromatic k nearest neighbor problem. We provide a query sensitive analysis, which shows that if the color classes form spatially well separated clusters (as often happens in practice), then queries can be answered quite efficiently. We also allow the user to specify an error bound ε⩾0, and consider the same problem in the context of approximate nearest neighbor searching. We present empirical evidence that for well clustered data sets, this approach leads to significant improvements in efficiency

On the Area of Overlap of Translated Polygons

(Also cross-referenced as CAR-TR-699) Given two simple polygons P and Q in the plane and a translation vector t E R2, the area-oJ-overlap function of P and Q is the function Ar(t) = Area(P n (t + Q)), where t + Q denotes Q translated by t. This function has a number of applications in areas such as motion planning and object recognition. We present a number of mathematical results regarding this function. We also provide efficient algorithms for computing a representation of this function, and for tracing contour curves of constant area of o verlap

Active Galactic Nuclei in Groups and Clusters of Galaxies: Detection and Host Morphology

The incidence and properties of Active Galactic Nuclei (AGN) in the field, groups, and clusters can provide new information about how these objects are triggered and fueled, similar to how these environments have been employed to study galaxy evolution. We have obtained new XMM-Newton observations of seven X-ray selected groups and poor clusters with 0.02 < z < 0.06 for comparison with previous samples that mostly included rich clusters and optically-selected groups. Our final sample has ten groups and six clusters in this low-redshift range (split at a velocity dispersion of $\sigma = 500$ km/s). We find that the X-ray selected AGN fraction increases from $f_A(L_X>10^{41}; M_R<M_R^*+1) = 0.047^{+0.023}_{-0.016}$ in clusters to $0.091^{+0.049}_{-0.034}$ for the groups (85% significance), or a factor of two, for AGN above an 0.3-8keV X-ray luminosity of $10^{41}$ erg/s hosted by galaxies more luminous than $M_R^*+1$. The trend is similar, although less significant, for a lower-luminosity host threshold of $M_R = -20$ mag. For many of the groups in the sample we have also identified AGN via standard emission-line diagnostics and find that these AGN are nearly disjoint from the X-ray selected AGN. Because there are substantial differences in the morphological mix of galaxies between groups and clusters, we have also measured the AGN fraction for early-type galaxies alone to determine if the differences are directly due to environment, or indirectly due to the change in the morphological mix. We find that the AGN fraction in early-type galaxies is also lower in clusters $f_{A,n>2.5}(L_X>10^{41}; M_R<M_R^*+1) = 0.048^{+0.028}_{-0.019}$ compared to $0.119^{+0.064}_{-0.044}$ for the groups (92% significance), a result consistent with the hypothesis that the change in AGN fraction is directly connected to environment.Comment: 18 pages, 9 figures; accepted by The Astrophysical Journal; for higher-resolution versions of some figures, see http://u.arizona.edu/~tjarnold/Arnold09

Cluster randomized controlled trial protocol: addressing reproductive coercion in health settings (ARCHES)

Background\ud Women ages 16–29 utilizing family planning clinics for medical services experience higher rates of intimate partner violence (IPV) and reproductive coercion (RC) than their same-age peers, increasing risk for unintended pregnancy and related poor reproductive health outcomes. Brief interventions integrated into routine family planning care have shown promise in reducing risk for RC, but longer-term intervention effects on partner violence victimization, RC, and unintended pregnancy have not been examined.\ud \ud Methods/Design\ud The ‘Addressing Reproductive Coercion in Health Settings (ARCHES)’ Intervention Study is a cluster randomized controlled trial evaluating the effectiveness of a brief, clinician-delivered universal education and counseling intervention to reduce IPV, RC and unintended pregnancy compared to standard-of-care in family planning clinic settings. The ARCHES intervention was refined based on formative research. Twenty five family planning clinics were randomized (in 17 clusters) to either a three hour training for all family planning clinic staff on how to deliver the ARCHES intervention or to a standard-of-care control condition. All women ages 16–29 seeking care in these family planning clinics were eligible to participate. Consenting clients use laptop computers to answer survey questions immediately prior to their clinic visit, a brief exit survey immediately after the clinic visit, a first follow up survey 12–20 weeks after the baseline visit (T2), and a final survey 12 months after the baseline (T3). Medical record chart review provides additional data about IPV and RC assessment and disclosure, sexual and reproductive health diagnoses, and health care utilization. Of 4009 women approached and determined to be eligible based on age (16–29 years old), 3687 (92 % participation) completed the baseline survey and were included in the sample.\ud \ud Discussion\ud The ARCHES Intervention Study is a community-partnered study designed to provide arigorous assessment of the short (3-4 months) and long-term (12 months) effects of a brief, clinician-delivered universal education and counseling intervention to reduce IPC, RC and unintended pregnancy in family planning clinic settings. The trial features a cluster randomized controlled trial design, a comprehensive data collection schedule and a large sample size with excellent retention.\ud \ud Trial Registration\ud ClinicialTrials.gov NCT01459458. Registered 10 October 2011

Massive Galaxies in COSMOS: Evolution of Black hole versus bulge mass but not versus total stellar mass over the last 9 Gyrs?

We constrain the ratio of black hole (BH) mass to total stellar mass of type-1 AGN in the COSMOS survey at 1<z<2. For 10 AGN at mean redshift z~1.4 with both HST/ACS and HST/NICMOS imaging data we are able to compute total stellar mass M_(*,total), based on restframe UV-to-optical host galaxy colors which constrain mass-to-light ratios. All objects have virial BH mass-estimates available from the COSMOS Magellan/IMACS and zCOSMOS surveys. We find zero difference between the M_BH--M_(*,total)-relation at z~1.4 and the M_BH--M_(*,bulge)-relation in the local Universe. Our interpretation is: (a) If our objects were purely bulge-dominated, the M_BH--M_(*,bulge)-relation has not evolved since z~1.4. However, (b) since we have evidence for substantial disk components, the bulges of massive galaxies (logM_(*,total)=11.1+-0.25 or logM_BH~8.3+-0.2) must have grown over the last 9 Gyrs predominantly by redistribution of disk- into bulge-mass. Since all necessary stellar mass exists in the galaxy at z=1.4, no star-formation or addition of external stellar material is required, only a redistribution e.g. induced by minor and major merging or through disk instabilities. Merging, in addition to redistributing mass in the galaxy, will add both BH and stellar/bulge mass, but does not change the overall final M_BH/M_(*,bulge) ratio. Since the overall cosmic stellar and BH mass buildup trace each other tightly over time, our scenario of bulge-formation in massive galaxies is independent of any strong BH-feedback and means that the mechanism coupling BH and bulge mass until the present is very indirect.Comment: Published in ApJL; 7 pages, 2 figures; updated to accepted version (methods changed, results unchanged

Stop Atherosclerosis in Native Diabetics Study (SANDS): Baseline Characteristics of the Randomized Cohort

Objectives: To present baseline characteristics of American Indians in the Stop Atherosclerosis in Native Diabetics Study (SANDS) and compare them with population-based data from American Indians and other ethnic groups. Design: 499 people with type 2 diabetes ≥ age 40, without known CVD, were recruited for a randomized 3-year trial to evaluate treatment targets for LDL-C (70 vs. 100 mg/dL) and systolic blood pressure (BP) (115 vs. 130 mmHg). Baseline evaluations included physical exam, collection of blood and urine samples, and carotid ultrasound and echocardiographic measures. Results: Mean age was 56 years; 66% were female. Average BMI was 33 kg/m2. Average duration of both hypertension and diabetes was 10 years, average A1c was 8.0 %, and mean LDL-C was 104 mg/dL. Participants in the conventional treatment group had slightly higher systolic BPs than participants in the aggressive treatment group (133 mm Hg vs. 128 mm Hg, p \u3c 0.002). Compared with the population-based cohorts of the Strong Heart Study (SHS), NHANES, and the TRIAD registry, SANDS participants had similar values for lipids, BP, and CRP, as well as degree of obesity, smoking rates, and renal function as indicated by estimated glomerular filtration rate. Conclusions: The baseline characteristics of the SANDS cohort are similar to those of a population-based sample of American Indian diabetic men and women and closely resemble diabetic men and women of other ethnic groups. Results from this study can be used to identify appropriate targets for LDL-C and BP lowering in diabetic American Indians and diabetic patients in other ethnic groups

A video-based educational intervention for providers regarding colorectal cancer screening

Methods: Email sent to providers asking them to complete a 7 question survey regarding knowledge and self-reported comfort in screening for colorectal cancer using a shared decision-making approach.https://jdc.jefferson.edu/patientsafetyposters/1045/thumbnail.jp

The zCOSMOS 10k-Bright Spectroscopic Sample

We present spectroscopic redshifts of a large sample of galaxies with I_(AB) < 22.5 in the COSMOS field, measured from spectra of 10,644 objects that have been obtained in the first two years of observations in the zCOSMOS-bright redshift survey. These include a statistically complete subset of 10,109 objects. The average accuracy of individual redshifts is 110 km s^(–1), independent of redshift. The reliability of individual redshifts is described by a Confidence Class that has been empirically calibrated through repeat spectroscopic observations of over 600 galaxies. There is very good agreement between spectroscopic and photometric redshifts for the most secure Confidence Classes. For the less secure Confidence Classes, there is a good correspondence between the fraction of objects with a consistent photometric redshift and the spectroscopic repeatability, suggesting that the photometric redshifts can be used to indicate which of the less secure spectroscopic redshifts are likely right and which are probably wrong, and to give an indication of the nature of objects for which we failed to determine a redshift. Using this approach, we can construct a spectroscopic sample that is 99% reliable and which is 88% complete in the sample as a whole, and 95% complete in the redshift range 0.5 < z < 0.8. The luminosity and mass completeness levels of the zCOSMOS-bright sample of galaxies is also discussed