Measuring Gravitational Lensing Flexions in Abell 1689 Using an Analytic Image Model

Measuring dark matter substructure within galaxy cluster haloes is a fundamental probe of the Lambda-CDM model of structure formation. Gravitational lensing is a technique for measuring the total mass distribution which is independent of the nature of the gravitating matter, making it a vital tool for studying these dark-matter dominated objects. We present a new method for measuring weak gravitational lensing flexions, the gradients of the lensing shear field, to measure mass distributions on small angular scales. While previously published methods for measuring flexions focus on measuring derived properties of the lensed images, such as shapelet coefficients or surface brightness moments, our method instead fits a mass-sheet-transformation-invariant Analytic Image Model (AIM) to the each galaxy image. This simple parametric model traces the distortion of lensed image isophotes and constrains the flexion fields. We test the AIM method using simulated data images with realistic noise and a variety of unlensed image properties, and show that it successfully reproduces the input flexion fields. We also apply the AIM method for flexion measurement to Hubble Space Telescope observations of Abell 1689, and detect mass structure in the cluster using flexions measured with the AIM method.Comment: 44 pages, 4 figures, 3 tables. Accepted to ApJ. V2 (published version) has minor changes from V1; ApJ 736 (2011

The TREC2001 video track: information retrieval on digital video information

The development of techniques to support content-based access to archives of digital video information has recently started to receive much attention from the research community. During 2001, the annual TREC activity, which has been benchmarking the performance of information retrieval techniques on a range of media for 10 years, included a ”track“ or activity which allowed investigation into approaches to support searching through a video library. This paper is not intended to provide a comprehensive picture of the different approaches taken by the TREC2001 video track participants but instead we give an overview of the TREC video search task and a thumbnail sketch of the approaches taken by different groups. The reason for writing this paper is to highlight the message from the TREC video track that there are now a variety of approaches available for searching and browsing through digital video archives, that these approaches do work, are scalable to larger archives and can yield useful retrieval performance for users. This has important implications in making digital libraries of video information attainable

Access to care issues adversely affect breast cancer patients in Mexico: oncologists’ perspective

Background: Despite recently implemented access to care programs, Mexican breast cancer (BC) mortality rates remain substantially above those in the US. We conducted a survey among Mexican Oncologists to determine whether practice patterns may be responsible for these differences. Methods: A web-based survey was sent to 851 oncologists across Mexico using the Vanderbilt University REDCap database. Analyses of outcomes are reported using exact and binomial confidence bounds and tests. Results: 138 participants (18.6% of those surveyed) from the National capital and 26 Mexican states, responded. Respondents reported that 58% of newly diagnosed BC patients present with stage III-IV disease; 63% undergo mastectomy, 52% axillary lymph node dissection (ALND) and 48% sentinel lymph node biopsy (SLNB). Chemotherapy is recommended for tumors > 1 cm (89%), positive nodes (86.5%), triple-negative (TN) (80%) and HER2 positive tumors (58%). Trastuzumab is prescribed in 54.3% and 77.5% for HER2 1 cm tumors, respectively. Tamoxifen is indicated for premenopausal hormone receptor (HR) positive tumors in 86.5% of cases and aromatase inhibitors (AI’s) for postmenopausal in 86%. 24% of physicians reported treatment limitations, due to delayed or incomplete pathology reports and delayed or limited access to medications. Conclusions: Even though access to care programs have been recently applied nationwide, women commonly present with advanced BC, leading to increased rates of mastectomy and ALND. Mexican physicians are dissatisfied with access to appropriate medical care. Our survey detects specific barriers that may impact BC outcomes in Mexico and warrant further investigation. Electronic supplementary material The online version of this article (doi:10.1186/1471-2407-14-658) contains supplementary material, which is available to authorized users

Comparative efficacy of ultrasound-guided and stimulating popliteal-sciatic perineural catheters for postoperative analgesia

Perineural catheter insertion using ultrasound guidance alone is a relatively new approach. Previous studies have shown that ultrasound-guided catheters take less time to place with high placement success rates, but the analgesic efficacy compared with the established stimulating catheter technique remains unknown. We tested the hypothesis that popliteal-sciatic perineural catheter insertion relying exclusively on ultrasound guidance results in superior postoperative analgesia compared with stimulating catheters. Preoperatively, subjects receiving a popliteal-sciatic perineural catheter for foot or ankle surgery were assigned randomly to either ultrasound guidance (bolus via needle with non-stimulating catheter insertion) or electrical stimulation (bolus via catheter). We used 1.5% mepivacaine 40 mL for the primary surgical nerve block and 0.2% ropivacaine (basal 8 mL·hr−1; bolus 4 mL; 30 min lockout) was infused postoperatively. The primary outcome was average surgical pain on postoperative day one. Forty of the 80 subjects enrolled were randomized to each treatment group. One of 40 subjects (2.5%) in the ultrasound group failed catheter placement per protocol vs nine of 40 (22.5%) in the stimulating catheter group (P = 0.014). The difference in procedural duration (mean [95% confidence interval (CI)]) was −6.48 (−9.90 - −3.05) min, with ultrasound requiring 7.0 (4.0-14.1) min vs stimulation requiring 11.0 (5.0-30.0) min (P < 0.001). The average pain scores of subjects who provided data on postoperative day one were somewhat higher for the 33 ultrasound subjects than for the 26 stimulation subjects (5.0 [1.0-7.8] vs 3.0 [0.0-6.5], respectively; P = 0.032), a difference (mean [95%CI]) of 1.37 (0.03-2.71). For popliteal-sciatic perineural catheters, ultrasound guidance takes less time and results in fewer placement failures compared with stimulating catheters. However, analgesia may be mildly improved with successfully placed stimulating catheters. Clinical trial registration number NCT00876681

Direct entropy determination and application to artificial spin ice

From thermodynamic origins, the concept of entropy has expanded to a range of statistical measures of uncertainty, which may still be thermodynamically significant. However, laboratory measurements of entropy continue to rely on direct measurements of heat. New technologies that can map out myriads of microscopic degrees of freedom suggest direct determination of configurational entropy by counting in systems where it is thermodynamically inaccessible, such as granular and colloidal materials, proteins and lithographically fabricated nanometre-scale arrays. Here, we demonstrate a conditional-probability technique to calculate entropy densities of translation-invariant states on lattices using limited configuration data on small clusters, and apply it to arrays of interacting nanometre-scale magnetic islands (artificial spin ice). Models for statistically disordered systems can be assessed by applying the method to relative entropy densities. For artificial spin ice, this analysis shows that nearest-neighbour correlations drive longer-range ones.Comment: 10 page

Interactions between downslope flows and a developing cold-air pool

A numerical model has been used to characterize the development of a region of enhanced cooling in an alpine valley with a width of order (Formula presented.) km, under decoupled stable conditions. The region of enhanced cooling develops largely as a region of relatively dry air which partitions the valley atmosphere dynamics into two volumes, with airflow partially trapped within the valley by a developing elevated inversion. Complex interactions between the region of enhanced cooling and the downslope flows are quantified. The cooling within the region of enhanced cooling and the elevated inversion is almost equally partitioned between radiative and dynamic effects. By the end of the simulation, the different valley atmospheric regions approach a state of thermal equilibrium with one another, though this cannot be said of the valley atmosphere and its external environment.Peer reviewe

Factors influencing quality of life following lower limb amputation for peripheral arterial occlusive disease: a systematic review of the literature

Background: The majority of lower limb amputations are undertaken in people with peripheral arterial occlusive disease,\ud and approximately 50% have diabetes. Quality of life is an important outcome in lower limb amputations; little is known\ud about what influences it, and therefore how to improve it.\ud Objectives: The aim of this systematic review was to identify the factors that influence quality of life after lower limb\ud amputation for peripheral arterial occlusive disease.\ud Methods: MEDLINE, EMBASE, CINAHL, PsycINFO, Web of Science and Cochrane databases were searched to identify\ud articles that quantitatively measured quality of life in those with a lower limb amputation for peripheral arterial occlusive\ud disease. Articles were quality assessed by two assessors, evidence tables summarised each article and a narrative\ud synthesis was performed.\ud Study design: Systematic review.\ud Results: Twelve articles were included. Study designs and outcome measures used varied. Quality assessment scores\ud ranged from 36% to 92%. The ability to walk successfully with a prosthesis had the greatest positive impact on quality\ud of life. A trans-femoral amputation was negatively associated with quality of life due to increased difficulty in walking\ud with a prosthesis. Other factors such as older age, being male, longer time since amputation, level of social support and\ud presence of diabetes also negatively affected quality of life.\ud Conclusion: Being able to walk with a prosthesis is of primary importance to improve quality of life for people with lower\ud limb amputation due to peripheral arterial occlusive disease. To further understand and improve the quality of life of this\ud population, there is a need for more prospective longitudinal studies, with a standardised outcome measure

Novel Association of HK1 with Glycated Hemoglobin in a Non-Diabetic Population: A Genome-Wide Evaluation of 14,618 Participants in the Women's Genome Health Study

Type 2 diabetes is a leading cause of morbidity and mortality. While genetic variants have been found to influence the risk of type 2 diabetes mellitus, relatively few studies have focused on genes associated with glycated hemoglobin, an index of the mean blood glucose concentration of the preceding 8–12 weeks. Epidemiologic studies and randomized clinical trials have documented the relationship between glycated hemoglobin levels and the development of long-term complications in diabetes; moreover, higher glycated hemoglobin levels in the subdiabetic range have been shown to predict type 2 diabetes risk and cardiovascular disease. To examine the common genetic determinants of glycated hemoglobin levels, we performed a genome-wide association study that evaluated 337,343 SNPs in 14,618 apparently healthy Caucasian women. The results show that glycated hemoglobin levels are associated with genetic variation at the GCK (rs730497; P = 2.8×10−12), SLC30A8 (rs13266634; P = 9.8×10−8), G6PC2 (rs1402837; P = 6.8×10−10), and HK1 (rs7072268; P = 6.4×10−9) loci. While associations at the GCK, SLC30A8, and G6PC2 loci are confirmatory, the findings at HK1 are novel. We were able to replicate this novel association in an independent validation sample of 455 additional non-diabetic men and women. HK1 encodes the enzyme hexokinase, the first step in glycolysis and a likely candidate for the control of glucose metabolism. This observed genetic association between glycated hemoglobin levels and HK1 polymorphisms paves the way for further studies of the role of HK1 in hemoglobin glycation, glucose metabolism, and diabetes