A Metrizable Topology on the Contracting Boundary of a Group

The 'contracting boundary' of a proper geodesic metric space consists of equivalence classes of geodesic rays that behave like rays in a hyperbolic space. We introduce a geometrically relevant, quasi-isometry invariant topology on the contracting boundary. When the space is the Cayley graph of a finitely generated group we show that our new topology is metrizable.Comment: v1: 26 pages, 3 figures; v2: 44 pages, 6 figures, additional results; v3: 46 pages, 7 figures, minor change

Apparatus and method for aerodynamic levitation

An apparatus for the levitation of a liquid drop by a fluid flow comprising a profile generator, a fluid flow supply means operatively connected to the profile generator. The profile generator includes an elongate cylindrical shell in which is contained a profiling means for configuring the velocity profile of the fluid flow exiting the profile generator

Multicenter Validation of the Vasoactive-Ventilation-Renal Score as a Predictor of Prolonged Mechanical Ventilation After Neonatal Cardiac Surgery

Objectives: We sought to validate the Vasoactive-Ventilation-Renal score, a novel disease severity index, as a predictor of outcome in a multicenter cohort of neonates who underwent cardiac surgery. Design: Retrospective chart review. Setting: Seven tertiary-care referral centers. Patients: Neonates defined as age less than or equal to 30 days at the time of cardiac surgery. Interventions: Ventilation index, Vasoactive-Inotrope Score, serum lactate, and Vasoactive-Ventilation-Renal score were recorded for three postoperative time points: ICU admission, 6 hours, and 12 hours. Peak values, defined as the highest of the three measurements, were also noted. Vasoactive-Ventilation-Renal was calculated as follows: ventilation index + Vasoactive-Inotrope Score + Δ creatinine (change in creatinine from baseline × 10). Primary outcome was prolonged duration of mechanical ventilation, defined as greater than 96 hours. Receiver operative characteristic curves were generated, and abilities of variables to correctly classify prolonged duration of mechanical ventilation were compared using area under the curve values. Multivariable logistic regression modeling was also performed. Measurements and Main Results: We reviewed 275 neonates. Median age at surgery was 7 days (25th–75th percentile, 5–12 d), 86 (31%) had single ventricle anatomy, and 183 (67%) were classified as Society of Thoracic Surgeons-European Association for Cardio-Thoracic Surgery Congenital Heart Surgery Mortality Category 4 or 5. Prolonged duration of mechanical ventilation occurred in 89 patients (32%). At each postoperative time point, the area under the curve for prolonged duration of mechanical ventilation was significantly greater for the Vasoactive-Ventilation-Renal score as compared to the ventilation index, Vasoactive-Inotrope Score, and serum lactate, with an area under the curve for peak Vasoactive-Ventilation-Renal score of 0.82 (95% CI, 0.77–0.88). On multivariable analysis, peak Vasoactive-Ventilation-Renal score was independently associated with prolonged duration of mechanical ventilation, odds ratio (per 1 unit increase): 1.08 (95% CI, 1.04–1.12). Conclusions: In this multicenter cohort of neonates who underwent cardiac surgery, the Vasoactive-Ventilation-Renal score was a reliable predictor of postoperative outcome and outperformed more traditional measures of disease complexity and severity

On Infrared Excesses Associated With Li-Rich K Giants

Infrared (IR) excesses around K-type red giants (RGs) have previously been discovered using IRAS data, and past studies have suggested a link between RGs with overabundant Li and IR excesses, implying the ejection of circumstellar shells or disks. We revisit the question of IR excesses around RGs using higher spatial resolution IR data, primarily from WISE. Our goal was to elucidate the link between three unusual RG properties: fast rotation, enriched Li, and IR excess. We have 316 targets thought to be K giants, about 40% of which we take to be Li-rich. In 24 cases with previous detections of IR excess at low spatial resolution, we believe that source confusion is playing a role, in that either (a) the source that is bright in the optical is not responsible for the IR flux, or (b) there is more than one source responsible for the IR flux as measured in IRAS. We looked for IR excesses in the remaining sources, identifying 28 that have significant IR excesses by ~20 um (with possible excesses for 2 additional sources). There appears to be an intriguing correlation in that the largest IR excesses are all in Li-rich K giants, though very few Li-rich K giants have IR excesses (large or small). These largest IR excesses also tend to be found in the fastest rotators. There is no correlation of IR excess with the carbon isotopic ratio, 12C/13C. IR excesses by 20 um, though relatively rare, are at least twice as common among our sample of Li-rich K giants. If dust shell production is a common by-product of Li enrichment mechanisms, these observations suggest that the IR excess stage is very short-lived, which is supported by theoretical calculations. Conversely, the Li-enrichment mechanism may only occasionally produce dust, and an additional parameter (e.g., rotation) may control whether or not a shell is ejected.Comment: 73 pages, 21 figures (some of which substantially degraded to meet arXiv file size requirements), accepted to AJ. Full table 1 (and full-res figures) available upon request to the autho

Determining subpopulation methylation profiles from bisulfite sequencing data of heterogeneous samples using DXM

Epigenetic changes, such as aberrant DNA methylation, contribute to cancer clonal expansion and disease progression. However, identifying subpopulation-level changes in a heterogeneous sample remains challenging. Thus, we have developed a computational approach, DXM, to deconvolve the methylation profiles of major allelic subpopulations from the bisulfite sequencing data of a heterogeneous sample. DXM does not require prior knowledge of the number of subpopulations or types of cells to expect. We benchmark DXM\u27s performance and demonstrate improvement over existing methods. We further experimentally validate DXM predicted allelic subpopulation-methylation profiles in four Diffuse Large B-Cell Lymphomas (DLBCLs). Lastly, as proof-of-concept, we apply DXM to a cohort of 31 DLBCLs and relate allelic subpopulation methylation profiles to relapse. We thus demonstrate that DXM can robustly find allelic subpopulation methylation profiles that may contribute to disease progression using bisulfite sequencing data of any heterogeneous sample

Valuing seasonal climate forecasts in Australian agriculture: northern grains case study

Objective of this report This report focuses on the value of SCFs to the management of grains farms in the Grains Research and Development Corporation (GRDC) northern panel region. The key decision identified by industry was which summer crop to sow. Four potential options were considered, sorghum, cotton, mungbean and summer fallow. The timing of this decision was early October for a rainfall forecast from October to December. Rainfall over this period can have an important influence on crop production. A skilful seasonal climate forecast is potentially valuable if it helps farmers make a different summer cropping decision compared with the decision made based on historical average rainfall. Key findings A general finding was that forecasts that led to decisions that run contrary to the direction of conditions provided the most value. For example, a wet forecast under low initial soil moisture and high relative sorghum price was valuable as it triggered a change from mungbean to sorghum. This finding has some parallels with observations of Hirshleifer and Riley (1992) that the ‘news-worthiness’ of information is a critical determinant of its value. It is important to recognise that the decision investigated here represents only part of the risk grain growers manage. The case study necessarily only represented one site and one production system and other sites, systems and decisions may find different results. However, it is likely that the general findings around the circumstances for which forecast value was found will provide insights for the use and value of SCFs for grain growers more widely

Extubation Failure after Neonatal Cardiac Surgery: A Multicenter Analysis

Objectives To describe the epidemiology of extubation failure and identify risk factors for its occurrence in a multicenter population of neonates undergoing surgery for congenital heart disease. Study design We conducted a prospective observational study of neonates ≤30 days of age who underwent cardiac surgery at 7 centers within the US in 2015. Extubation failure was defined as reintubation within 72 hours of the first planned extubation. Risk factors were identified with the use of multivariable logistic regression analysis and reported as OR with 95% CIs. Multivariable logistic regression analysis was conducted to examine the relationship between extubation failure and worse clinical outcome, defined as hospital length of stay in the upper 25% or operative mortality. Results We enrolled 283 neonates, of whom 35 (12%) failed their first extubation at a median time of 7.5 hours (range 1-70 hours). In a multivariable model, use of uncuffed endotracheal tubes (OR 4.6; 95% CI 1.8-11.6) and open sternotomy of 4 days or more (OR 4.8; 95% CI 1.3-17.1) were associated independently with extubation failure. Accordingly, extubation failure was determined to be an independent risk factor for worse clinical outcome (OR 5.1; 95% CI 2-13). Conclusions In this multicenter cohort of neonates who underwent surgery for congenital heart disease, extubation failure occurred in 12% of cases and was associated independently with worse clinical outcome. Use of uncuffed endotracheal tubes and prolonged open sternotomy were identified as independent and potentially modifiable risk factors for the occurrence of this precarious complication