3,305 research outputs found

    Self-similar states and projections in noncommutative metric spaces

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    We present a generalisation of the theory of iterated function systems and associated fractals to the setting of noncommutative geometry. Along the way, we discuss some ideas surrounding locally compact noncommutative metric spaces

    Habitat selection by the relict leopard frog (Rana onca): Assessment of vegetation use at two scales

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    In recent years, two populations of the rare Relict Leopard Frog (Rana onca) have gone extinct. These population extinctions occurred concomitantly with the encroachment of native emergent vegetation into pools in which frogs were usually observed. In order to determine if adult Rana onca prefer more vegetatively open habitats, a radio-telemetry study was conducted. A total of 809 radio telemetry observations were made on 34 frogs from April 2 through December 7, 2004. Binary Logistic Regression was used with both macrohabitat and microhabitat data to compare habitat characteristics between low-use and high-use segments of the spring. A more traditional multiple analysis of variance (MANOVA) approach was also used at the macrohabitat scale to compare used segments to non-used segments. Both of these analyses supported the hypothesis that adult Rana onca select for areas with less vegetative cover

    Near infrared lymphatic mapping in thoracic malignancies

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    Thesis (M.A.)--Boston UniversityLung cancer is the leading cause of all cancer deaths in men and women combined, killing more than 150,000 patients per year. Lymph node status is the best predictor of survival in patients with surgically resectable lung cancer. The 5 year survival rates for node negative (N0), hilar node positive (N1), and mediastinal node positive (N2) disease is 53.8%, 26.3%, and 20.8%, respectively. Accurate staging of the disease will lead to the most effective adjuvant therapy strategy. However, routine pathologic analysis of sampled lymph nodes underestimates the prevalence of metastatic disease. Patients with missed metastatic disease do not receive proper treatment which likely contributes to the high recurrence rate and poor 5 year survival of lung cancer patients. Detection of lymph nodes at highest risk for harboring metastatic disease (i.e. sentinel lymph nodes (SLN)) may permit more intensive histologic analysis to detect occult disease. Presently there is no safe and reliable method for detecting SLNs. The overall objective of this project was to identify the SLNs and treat them. To do this, we looked at the feasibility of using indocyanine green (ICG) and near infrared (NIR) imaging in a minimally invasive video assisted thoracic surgery procedure to identify the SLNs in patients with suspected Stage I/II non small cell lung cancer (NSCLC). Previous attempts at SLN identification in patients with NSCLC using radioisotopes and blue dyes have been ineffective. ICG and NIR imaging for identification of SLNs has become standard of care in both melanoma and breast cancer. We looked to extend this technology to NSCLC. Patients were given an intraparenchymal, peritumoral injection of ICG and imaged with a NIR camera noting lymphatic migration, time to SLN identification, number of SLNs, and lymph node station. Our results demonstrated the increased rate of SLN identification over the previous studies. [TRUNCATED

    The Globular Cluster Systems in the Coma Ellipticals. III: The Unique Case of IC 4051

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    Using archival \hst WFPC2 data, we derive the metallicity distribution, luminosity function, and spatial structure of the globular cluster system around IC 4051, a giant E galaxy on the outskirts of the Coma cluster core. The metallicity distribution derived from the (V-I) colors has a mean [Fe/H] = -0.3, a near-complete lack of metal-poor clusters, and only a small metallicity gradient with radius; it may, however, have two roughly equal metallicity subcomponents, centered at [Fe/H] ~ 0.0 and -1.0. The luminosity distribution (GCLF) has the Gaussian-like form observed in all other giant E galaxies, with a peak (turnover) at V = 27.8, consistent with a Coma distance of 100 Mpc. The radial profiles of both the GCS and the halo light show an unusually steep falloff which may indicate that the halo of this galaxy has been tidally truncated. Lastly, the specific frequency of the GCS is remarkably large: we find S_N = 11 +- 2, resembling the central cD-type galaxies even though IC 4051 is not a cD or brightest cluster elliptical. A formation model consistent with most of the observations would be that this galaxy was subjected to removal of a large fraction of its protogalactic gas shortly after its main phase of globular cluster formation, probably by its first passage through the Coma core. Since then, no significant additions due to accretions or mergers have taken place.Comment: 24 pp. plus 13 Figures. Postscript file for the complete paper can also be downloaded from http://www.physun.mcmaster.ca/~harris/WEHarris.html. Astron.J., in pres

    Obesity prevalence and associated risk factors in outdoor living domestic horses and ponies

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    Reasons for performing study. The prevalence of obesity in companion animals, including horses and ponies has risen drastically in recent years and risk factors have been little investigated. Horses are unique amongst companion animals in that many are outdoor-living and forage independently on pasture; they also have a dual utility and companionship role. The body condition of wild and free-living equines is known to vary seasonally, yet previous estimates of the prevalence of obesity and associated risk factors in domestic animals do not consider this. Most previous studies were conducted during the summer months when pasture quality is greater and obesity prevalence is likely to be highest. In addition, many previous estimates do not use validated body condition scoring methods and rely on owner reporting.Objectives. To examine the prevalence and risk factors predictive of equine obesity at both the end of winter and the end of summer, in a domestic population of leisure horses with daily access to pasture. Using validated body condition scoring methods and a single, trained observer.Methods. Body condition and belly girth measurements were taken at the end of winter and during the summer in a population of leisure horses (n = 96) with outdoor pasture access for β‰₯6 h per day. Risk factor information was obtained by two owner questionnaires and analysed statistically using a mixed effects logistic regression model. The dependent variable was obese (BCS β‰₯ 7/9) or non-obese (BCS < 7/9). Risk factors associated with seasonal change in belly girth were also explored using a mixed effects linear regression model.Results. Obesity prevalence rose significantly from 27.08% at the end of winter to 35.41% during summer (p < 0.001). Breed was the risk factor most strongly associated with obesity (p < 0.001). Supplementary feed was not a strong predictor and there was no association with low intensity structured exercise. As winter BCS increased, the percentage seasonal change in belly girth decreased.Conclusions. Obesity prevalence differed between winter and summer in domestic equines. Supplementary feed and low intensity structured exercise in equines living outdoors for β‰₯6 h per day had limited or no effect on obesity levels. Seasonal variation in body condition was lower in obese equines.Potential relevance. It is important to consider season when studying equine obesity and obesity-associated disorders. Risk factor analysis suggests preventative measures may need to be breed specific. The metabolic implications of a lessened seasonal change in body condition in obese animals, warrants investigation

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