2,570 research outputs found

    Spanning forest polynomials and the transcendental weight of Feynman graphs

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    We give combinatorial criteria for predicting the transcendental weight of Feynman integrals of certain graphs in Ï•4\phi^4 theory. By studying spanning forest polynomials, we obtain operations on graphs which are weight-preserving, and a list of subgraphs which induce a drop in the transcendental weight.Comment: 30 page

    Instrumentation for Measurement of Gas Permeability of Polymeric Membranes

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    A mass spectrometric 'Dynamic Delta' method for the measurement of gas permeability of polymeric membranes has been developed. The method is universally applicable for measurement of the permeability of any gas through polymeric membrane materials. The usual large sample size of more than 100 square centimeters required for other methods is not necessary for this new method which requires a size less than one square centimeter. The new method should fulfill requirements and find applicability for industrial materials such as food packaging, contact lenses and other commercial materials where gas permeability or permselectivity properties are important

    Outcomes with As-Needed Ranibizumab after Initial Monthly Therapy: Long-Term Outcomes of the Phase III RIDE and RISE Trials.

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    PURPOSE: To determine whether the efficacy and safety achieved with monthly ranibizumab as treatment for diabetic macular edema (DME) can be maintained with less-than-monthly treatment. DESIGN: Open-label extension (OLE) phase of randomized, sham-controlled phase III trials: RIDE (NCT00473382) and RISE (NCT00473330). PARTICIPANTS: Five hundred of 582 adults who completed the 36-month randomized core studies elected to enter the OLE. METHODS: All patients participating in the OLE were eligible to receive 0.5 mg ranibizumab according to predefined re-treatment criteria: Treatment was administered when DME was identified by the investigator on optical coherence tomography or when best-corrected visual acuity (BCVA) worsened by ≥5 Early Treatment Diabetic Retinopathy Study letters versus month 36. Patients were observed at 30-, 60-, or 90-day intervals depending on the need for treatment. MAIN OUTCOME MEASURES: The incidence and severity of ocular and nonocular events, proportion of patients with ≥15-letter best-corrected visual acuity (BCVA) gain from baseline, mean BCVA change from month 36 (final core study visit), mean central foveal thickness (CFT), and mean CFT change from month 36. RESULTS: A mean of 4.5 injections were administered over a mean follow-up of 14.1 months. Approximately 25% of patients did not require further treatment based on protocol-defined re-treatment criteria. Mean BCVA was sustained or improved in these patients through the end of follow-up. Approximately 75% of patients received ≥1 criteria-based re-treatment; mean time to first re-treatment was approximately 3 months after the last masked-phase visit. Mean BCVA remained stable in re-treated patients; CFT was generally stable with a trend toward slight thickening in all patients when mandatory monthly therapy was relaxed. CONCLUSIONS: Vision gains achieved after 1 or 3 years of monthly ranibizumab therapy were maintained with a marked reduction in treatment frequency; some patients required no additional treatment. These observations are consistent with other studies evaluating induction followed by maintenance ranibizumab therapy for DME. Patients whose treatment was deferred by 2 years (randomized initially to sham) did not ultimately achieve the same BCVA gains as patients who received ranibizumab from baseline. Ranibizumab\u27s safety profile in the OLE appeared similar to that observed in the controlled core studies and other studies

    Optical Measurements at the Combustor Exit of the HIFiRE 2 Ground Test Engine

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    The development of optical techniques capable of measuring in-stream flow properties of air breathing hypersonic engines is a goal of the Aerospace Propulsion Division at AFRL. Of particular interest are techniques such as tunable diode laser absorption spectroscopy that can be implemented in both ground and flight test efforts. We recently executed a measurement campaign at the exit of the combustor of the HIFiRE 2 ground test engine during Phase II operation of the engine. Data was collected in anticipation of similar data sets to be collected during the flight experiment. The ground test optical data provides a means to evaluate signal processing algorithms particularly those associated with limited line of sight tomography. Equally important, this in-stream data was collected to compliment data acquired with surface-mounted instrumentation and the accompanying flowpath modeling efforts-both CFD and lower order modeling. Here we discuss the specifics of hardware and data collection along with a coarse-grained look at the acquired data and our approach to processing and analyzing it

    Enhanced deep-blue emission from Pt(II) complexes bound to 2-pyridyltetrazolate and an ortho-xylene-linked bis(NHC)cyclophane

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    The coordination of 2-pyridyltetrazolate and ortho-xylene-linked bis(NHC)cyclophane to Pt(II) yielded a novel complex characterised by enhanced pure deep-blue emission, whose intensity can be modulated via methylation of the tetrazole ring

    Reproductive Biology of Cobia, Rachycentron canadum, from Coastal Waters of the Southern United States

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    Reproductive biology of the cobia, Rachycentron canadum, is described from four coastal areas in the southern United States. Samples were obtained from recreational fishermen between December 1995 and November 1997 from the southeastern United States (Morehead City, NC, to Cape Canaveral, FL), the eastern Gulf of Mexico (Ft. Myers to Crystal River, FL), the north-central Gulf of Mexico (Destin, FL, to Chandeleur Islands, LA) and the western Gulf of Mexico (Port Aransas, TX). Histological evidence of spawning occurred from April through September in all areas. Some female cobia (17-32%) throughout the Gulf of Mexico had spent or regressed ovaries by July. Gonadosomatic index peaked between May and July throughout the region. Ovaries of females from all areas contained both postovulatory follicles (POF) and oocytes in final oocyte maturation (FOM) during all months of the reproductive season. Batch fecundity was calculated by using three different methods: oocytes \u3e700 pm were fixed in 1) Gilson\u27s fixative or 2) 10% neutral buffered formalin (NBF), and 3)oocytes undergoing FOM were sectioned for histological examination. Mean batch fecundity ranged from 377,000 +/- 64,500 to 1,980,500 +/- 1,598,500 eggs; there was no significant difference among methods. Batch fecundity calculated with the NBF method showed a positive relationship with fork length (P=0.021, r(2)=0.132) and ovary-free body weight (OFBW; P=0.016, r(2)=0.143). Relative batch fecundity was not significantly different among months during the spawning season and averaged 53.1 +/-9.4 eggs/g OFBW for the NBF method and 29.1 +/- 4.8 eggs/g OFBW for the FOM method. Although spawning frequencies were not significantly differ ent among areas (P=0.07), cobia from the southeastern United States and north-central Gulf of Mexico were estimated to spawn once every 5 days, whereas cobia from the western Gulf of Mexico were estimated to spawn once every 9 to 12 days

    Reproductive Biology of Cobia, \u3ci\u3eRachycentron canadum\u3c/i\u3e, from Coastal Waters of the Southern United States

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    Reproductive biology of the cobia, Rachycentron canadum, is described from four coastal areas in the southern United States. Samples were obtained from recreational fishermen between December 1995 and November 1997 from the southeastern United States (Morehead City, NC, to Cape Canaveral, FL), the eastern Gulf of Mexico (Ft. Myers to Crystal River, FL), the north-central Gulf of Mexico (Destin, FL, to Chandeleur Islands, LA) and the western Gulf of Mexico (Port Aransas, TX). Histological evidence of spawning occurred from April through September in all areas. Some female cobia (17-32%) throughout the Gulf of Mexico had spent or regressed ovaries by July. Gonadosomatic index peaked between May and July throughout the region. Ovaries of females from all areas contained both postovulatory follicles (POF) and oocytes in final oocyte maturation (FOM) during all months of the reproductive season. Batch fecundity was calculated by using three different methods: oocytes \u3e700 μm were fixed in 1) Gilson’s fixative or 2) 10% neutral buffered formalin (NBF), and 3) oocytes undergoing FOM were sectioned for histological examination. Mean batch fecundity ranged from 377,000 ± 64,500 to 1,980,500 ± 1,598,500 eggs; there was no significant difference among methods. Batch fecundity calculated with the NBF method showed a positive relationship with fork length (P = 0.021, r2 = 0.132) and ovary-free body weight (OFBW; P = 0.016, r2 = 0.143). Relative batch fecundity was not significantly different among months during the spawning season and averaged 53.1 ± 9.4 eggs/g OFBW for the NBF method and 29.1 ± 4.8 eggs/g OFBW for the FOM method. Although spawning frequencies were not significantly different among areas (P = 0.07), cobia from the southeastern United States and north-central Gulf of Mexico were estimated to spawn once every 5 days, whereas cobia from the western Gulf of Mexico were estimated to spawn once every 9 to 12 days

    Substance Use, Mental Disorders and Physical Health of Caribbeans at-Home Compared to Those Residing in the United States

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    This study compares the health conditions of domestic Caribbeans with those living in the United States to explore how national context and migration experiences might influence substance use (i.e., alcohol or drug) and other mental and physical health conditions. The study is based upon probability samples of non-institutionalized Caribbeans living in the United States (1621), Jamaica (1216) and Guyana (2068) 18 years of age and over. Employing descriptive statistics and multivariate analytic procedures, the results revealed that substance use and other physical health conditions and major depressive disorder and mania vary by national context, with higher rates among Caribbeans living in the United States. Context and generation status influenced health outcomes. Among first generation black Caribbeans, residing in the United States for a longer length of time is linked to poorer health outcomes. There were different socio-demographic correlates of health among at-home and abroad Caribbeans. The results of this study support the need for additional research to explain how national context, migratory experiences and generation status contribute to understanding substance use and mental disorders and physical health outcomes among Caribbean first generation and descendants within the United States, compared to those remaining in the Caribbean region

    Standardising Costs or Standardising Care? Qualitative Evaluation of the Implementation and Impact of a Hospital Funding Reform in Ontario, Canada

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    Background  Since 2011, the Government of Ontario, Canada, has phased in hospital funding reforms hoping to encourage standardised, evidence-based clinical care processes to both improve patient outcomes and reduce system costs. One aspect of the reform – quality-based procedures (QBPs) – replaced some of each hospital’s global budget with a pre-set price per episode of care for patients with specific diagnoses or procedures. The QBP initiative included publication and dissemination of a handbook for each of these diagnoses or procedures, developed by an expert technical group. Each handbook was intended to guide hospitals in reducing inappropriate variation in patient care and cost by specifying an evidence-based episode of care pathway. We explored whether, how and why hospitals implemented these episode of care pathways in response to this initiative. Methods  We interviewed key informants at three levels in the healthcare system, namely individuals who conceived and designed the QBP policy, individuals and organisations supporting QBP adoption, and leaders in five case-study hospitals responsible for QBP implementation. Analysis involved an inductive approach, incorporating framework analysis to generate descriptive and explanatory themes from data. Results  The 46 key informants described variable implementation of best practice episode of care pathways across QBPs and across hospitals. Handbooks outlining evidence-based clinical pathways did not address specific barriers to change for different QBPs nor differences in hospitals’ capacity to manage change. Hospitals sometimes found it easier to focus on containing and standardising costs of care than on implementing standardised care processes that adhered to best clinical practices. Conclusion  Implementation of QBPs in Ontario’s hospitals depended on the interplay between three factors, namely complexity of changes required, internal capacity for organisational change, and availability and appropriateness of targeted external facilitators and supports to manage change. Variation in these factors across QBPs and hospitals suggests the need for more tailored and flexible implementation supports designed to fit all elements of the policy, rather than one-size-fits-all handbooks alone. Without such supports, hospitals may enact quick fixes aimed mainly at preserving budgets, rather than pursue evidence- and value-based changes in care management. Overestimating hospitals’ change management capacity increases the risk of implementation failure
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