A quantile‐based approach for relative efficiency measurement

Two popular approaches for efficiency measurement are a non‐stochastic approach called data envelopment analysis (DEA) and a parametric approach called stochastic frontier analysis (SFA). Both approaches have modeling difficulty, particularly for ranking firm efficiencies. In this paper, a new parametric approach using quantile statistics is developed. The quantile statistic relies less on the stochastic model than SFA methods, and accounts for a firm\u27s relationship to the other firms in the study by acknowledging the firm\u27s influence on the empirical model, and its relationship, in terms of similarity of input levels, to the other firms

Low temperature characterization of modulation doped SiGe grown on bonded silicon-on-insulator

Modulation doped pseudomorphic Si0.87Ge0.13 strained quantum wells were grown on bonded silicon-on-insulator (SOI) substrates. Comparison with similar structures grown on bulk Si(100) wafers shows that the SOI material has higher mobility at low temperatures with a maximum value of 16 810 cm 2/V s for 2.05 × 1011 cm – 2 carries at 298 mK. Effective masses obtained from the temperature dependence of Shubnikov–de Haas oscillations have a value of (0.27 ± 0.02) m0 compared to (0.23 ± 0.02) m0 for quantum wells on Si(100) while the cyclotron resonance effective masses obtained at higher magnetic fields without consideration for nonparabolicity effects have values between 0.25 and 0.29 m0. Ratios of the transport and quantum lifetimes, tau/tau q=2.13 ± 0.10, were obtained for the SOI material that are, we believe, the highest reported for any pseudomorphic SiGe modulation doped structure and demonstrates that there is less interface roughness or charge scattering in the SOI material than in metal–oxide–semiconductor field effect transistors or other pseudomorphic SiGe modulation doped quantum wells

Rainfall and Soils, Not Grazing Intensity, Determine the Composition and Productivity of Annual Plants in a Biodiverse Arid Winter Rainfall Region

Concentration of grazer activity around watering points and stock posts has led to well-documented vegetation impacts in arid and semi-arid rangelands. Effect of grazing and abiotic factors on perennial plant diversity have been reported in the bio-diverse winter rainfall vegetation of the Succulent Karoo in South Africa, but the impact on annuals had not been investigated. The aim of this study was to assess the effect of rainfall, soil nutrients, land forms and grazing on forage depletion, soil chemistry and the composition, diversity, richness and biomass production of annual plants in the Richtersveld National park, which is a contractual national park used by semi-nomadic pastoralists to herd goats and sheep. A grazing gradient away from stock posts at 100m, 500m and 1000m on sandy plains and rocky foothills at five study sites with different mean annual rainfall and vegetation types were used. Distance from stock posts corresponded to a gradient of forage depletion and resulted in changes in soil chemistry with distance. Biomass production, richness and diversity of annuals were correlated with rainfall but not significantly affected by landform or distance from stock posts. Rainfall and soil variables had a greater influence on species composition than grazing in this arid ecosystem. The decrease in perennial cover and richness near the stock posts was not accompanied by increase in biomass production or richness of annuals, which is expected to have adverse effects on overall plant diversity and forage availability. Keywords: Piosphere, Pastoralists, Rangeland, Succulent Karoo DOI: 10.7176/JNSR/12-10-04 Publication date:May 31st 202

Applying Machine Learning Techniques for Type2 Diabetes Readmission Prediction Based on Retrospective Data

Roughly 9.3% of US population suffer from diabetes and the 30 day readmission rate for diabetes patients range between 14.4 to 22.7%. Hence identifying the risk of readmission is a crucial information for the service providers to not only reduce the healthcare cost but also improve the quality of patient care. This paper models machine learning algorithms to compute probability of 30-day hospital readmission for type2 diabetes patients. Along with novel pre-processing techniques to identify the challenges of noisy and non-homogenized medical data, we used methods to downsize the feature vector size without sacrificing prediction accuracy. Our method has been implemented on a publicly available dataset from University of California Irvine at https://archive.ics.uci.edu/ml/datasets/diabetes+130-us+hospitals+for+years+1999-2008 which summarizes data from 130 US hospitals within span of 10 years with roughly 100,000 patients

The impact of the physical environment on depressive symptoms of older residents living in care homes : a mixed methods study

Background and Objectives: Forty percent of residents living in care homes in the United Kingdom have significant depressive symptoms. Care homes can appear to be depressing places, but whether the physical environment of homes directly affects depression in care home residents is unknown. This study explores the relationship between the physical environment and depressive symptoms of older people living in care homes. Research Design and Methods: In a prospective cohort study the physical environment of 50 care homes were measured using the Sheffield Care Environment Assessment Matrix (SCEAM) and depressive symptoms of 510 residents measured using the Geriatric Depression Scale (GDS-15). The study was supplemented with semi-structured interviews with residents living in the care homes. Quantitative data were analyzed using multi-level modeling, and qualitative data analyzed using a thematic framework approach. Results: The overall physical environment of care homes (overall SCEAM score) did not predict depressive symptoms. Controlling for dependency, social engagement, and home type, having access to outdoor space was the only environmental variable to significantly predict depressive symptoms. Residents interviewed reported that access to outdoor space was restricted in many ways: locked doors, uneven foot paths, steep steps, and needing permission or assistance to go outside. Discussion and Implications: We provide new evidence to suggest that access to outdoor space predicts depressive symptoms in older people living in care home. Interventions aimed at increasing access to outdoor spaces could positively affect depressive symptoms in older people

NMR Study of Ion Dynamics and Charge Storage in Ionic Liquid Supercapacitors.

Ionic liquids are emerging as promising new electrolytes for supercapacitors. While their higher operating voltages allow the storage of more energy than organic electrolytes, they cannot currently compete in terms of power performance. More fundamental studies of the mechanism and dynamics of charge storage are required to facilitate the development and application of these materials. Here we demonstrate the application of nuclear magnetic resonance spectroscopy to study the structure and dynamics of ionic liquids confined in porous carbon electrodes. The measurements reveal that ionic liquids spontaneously wet the carbon micropores in the absence of any applied potential and that on application of a potential supercapacitor charging takes place by adsorption of counterions and desorption of co-ions from the pores. We find that adsorption and desorption of anions surprisingly plays a more dominant role than that of the cations. Having elucidated the charging mechanism, we go on to study the factors that affect the rate of ionic diffusion in the carbon micropores in an effort to understand supercapacitor charging dynamics. We show that the line shape of the resonance arising from adsorbed ions is a sensitive probe of their effective diffusion rate, which is found to depend on the ionic liquid studied, as well as the presence of any solvent additives. Taken as whole, our NMR measurements allow us to rationalize the power performances of different electrolytes in supercapacitors.A.C.F., J.M.G., C.M., P.M.B., H.W., and C.P.G. acknowledge the Sims Scholarship (A.C.F), EPSRC (via the Supergen consortium, J.M.G.), The School of Physical Sciences (University of Cambridge) for funding through an Oppen- heimer Research Fellowship (C.M.), The Marie Curie FP7 International Incoming Fellowship (P.M.B.), and the EU ERC (via an Advanced Fellowship to C.P.G.) for funding. A.C.F. and J.M.G. thank the NanoDTC Cambridge for travel funding. P.S. acknowledges support from the European Research Council (ERC, Advanced Grant, ERC-2011-AdG, Project 291543−IONACES).This is the final version. It first appeared at http://pubs.acs.org/doi/abs/10.1021/jacs.5b03958

A multi-bacteriocin cheese starter system comprising nisin and lacticin 3147 in Lactococcus lactis, in combination with plantaricin from Lactobacillus plantarum

Functional starter cultures demonstrating superior technological and food safety properties are advantageous to the food fermentation industry. We evaluated the efficacy of single and double bacteriocin-producing starters of Lactococcus lactis capable of producing the Class I bacteriocins, nisin A and/or lacticin 3147 in terms of starter performance. Single producers were generated by mobilising the conjugative, bacteriophage resistance plasmid pMRC01, encoding lacticin genetic determinants, or the conjugative transposon Tn5276, encoding nisin genetic determinants, to the commercial starter L. lactis CSK2775. The effect of bacteriocin co-production was examined by superimposing pMRC01 into the newly constructed nisin transconjugant. Transconjugants were improved with regard to antimicrobial activity and bacteriophage insensitivity when compared to the recipient strain and the double producer was immune to both bacteriocins. Bacteriocin production in the starter was stable, although the recipient strain proved to be a more efficient acidifier than transconjugant derivatives. Overall, combining Class I bacteriocins (the double-producer or a combination of single producers) proved as effective as individual bacteriocins for controlling Listeria innocua growth in laboratory-scale cheeses. However, using the double producer in combination with the Class II bacteriocin producer Lactobacillus plantarum, or the lacticin producer with the Class II producer, proved most effective for reducing bacterial load. As emergence of bacteriocin tolerance was reduced 10-fold in the presence of nisin and lacticin, we suggest that the double producer in conjunction with the Class II producer could serve as a protective culture providing a food-grade, multi-hurdle approach to control pathogenic growth in a variety of industrial applications. IMPORTANCE: We generated a suite of single and double-bacteriocin producing starter cultures capable of generating the Class I bacteriocins lacticin 3147 or nisin or both bacteriocins simultaneously via conjugation. The transconjugants exhibited improved bacteriophage resistance and antimicrobial activity. The single producers proved as effective as the double-bacteriocin producer at reducing Listeria numbers in laboratory-scale cheese. However, combining the double producer or the lacticin producing starter with a Class II bacteriocin producer, Lactobacillus plantarum LMG P-26358, proved most effective at reducing Listeria numbers, and was significantly better than a combination of the three bacteriocin producing strains, as the double producer is not inhibited by either of the Class I bacteriocins. Since the simultaneous use of lacticin and nisin should reduce the emergence of bacteriocin tolerant derivatives this study suggests that a protective starter system produced by bacteriocin stacking is a worthwhile multi-hurdle approach for food safety applications

ACCEPTED MANUSCRIPT Bias in Markov Models of Disease

Abstract We examine bias in Markov models of diseases, including both chronic and infectious diseases. We consider two common types of Markov disease models: ones where disease progression changes by severity of disease, and ones where progression of disease changes in time or by age. We find sufficient conditions for bias to exist in models with aggregated transition probabilities when compared to models with state/time dependent transition probabilities. We also find that when aggregating data to compute transition probabilities, bias increases with the degree of data aggregation. We illustrate by examining bias in Markov models of Hepatitis C, Alzheimer's disease, and lung cancer using medical data and find that the bias is significant depending on the method used to aggregate the data. A key implication is that by not incorporating state/time dependent transition probabilities, studies that use Markov models of diseases may be significantly overestimating or underestimating disease progression. This could potentially result in incorrect recommendations from cost-effectiveness studies and incorrect disease burden forecasts

High Temperature Microwave Dielectric Properties of JSC-1AC Lunar Simulant

Microwave heating has many potential lunar applications including sintering regolith for lunar surface stabilization and heating regolith for various oxygen production reactors. The microwave properties of lunar simulants must be understood so this technology can be applied to lunar operations. Dielectric properties at microwave frequencies for a common lunar simulant, JSC-1AC, were measured up to 1100 C, which is approximately the melting point. The experimentally determined dielectric properties included real and imaginary permittivity (epsilon', epsilon"), loss tangent (tan delta), and half-power depth, the di stance at which a material absorbs 50% of incident microwave energy. Measurements at 2.45 GHz revealed tan delta of JSC-1A increases from 0.02 at 25 C to 0.31 at 110 C. The corresponding half-power depth decreases from a peak of 286 mm at 110 C, to 13 mm at 1100 C. These data indicate that JSC-1AC becomes more absorbing, and thus a better microwave heater as temperature increases. A half-power depth maximum at 100-200 C presents a barrier to direct microwave heating at low temperatures. Microwave heating experiments confirm the sluggish heating effect of weak absorption below 200 C, and increasingly strong absorption above 200 C, leading to rapid heating and melting of JSC-1AC