3,216 research outputs found

    Mobius Fermions: Improved Domain Wall Chiral Fermions

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    A new class of domain wall fermions is defined that interpolates between Shamir's and Bori\c{c}i's form without increasing the number of Dirac applications per CG iteration. This class represents a full (real) M\"obius transformation of the Wilson kernel. Simulations on quenched Wilson lattices with β=6.0\beta = 6.0 show that the number of lattice sites (LsL_s) in the fifth dimension can be reduced by a factor of 2 or more at fixed value of chiral symmetry violations measured by the residual mass (mresm_{res}).Comment: 3 pages, 1 figur

    Diabrotica virgifera virgifera LeConte, MOGUĆI UTJECAJ OKOLIŠNIH ČIMBENIKA I NAVODNJAVANJA KUKURUZA NA VELIČINU LIČINKI U SJEVEROZAPADNOJ ITALIJI

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    Western corn rootworm, Diabrotica virgifera virgifera LeConte, larvae were collected in different irrigated maize fields in Brescia Province in Northwestern Italy in 2006, 2007 and 2008. Head capsule widths, considered a valid indicator of larval instar stage, were measured for 2063 specimens and data for the three years were combined and grouped in increments of 20 µm width sizes. Frequency of larvae within each grouping was graphed as a histogram and three distinct peaks, interpreted to represent the peak frequency of the head capsule widths of the three larval instars, were observed. Assuming a normal distribution of head capsule widths, a multiple nonlinear Gaussian curve regression was applied to the frequency histogram. The peaks of the fitted normal curves were 227 ± 3 µm, 353 ± 6 µm, and 519 ± 3 µm for the first, second and third instars, respectively. These values are higher than those reported by other authors in similar studies. The possible impact of irrigation and other environmental factors is discussed.Ličinke kukuruzne zlatice, Diabrotica virgifera virgifera LeConte skupljane su u različito navodnjavanim poljima kukuruza provincije Brescia (SZ Italija) 2006., 2007. i 2008. godine. Širina glave smatra se valjanim pokazateljem razvojnih faza ličinki, stoga su obavljena mjerenja širine glave 2063 jedinki te vrste, a podatci trogodišnjih istraživanja spojeni su i rangirani u veličine od 20 μm širine. Frekvencija ličinki unutar istih rangiranja prikazana je grafički histogramom s tri vrha koji interpretiraju vrhove u frekvenciji širine glava ličinki triju različitih stadija razvoja. Za prikaz histograma frekvencija, uz pretpostavku normalne distribucije širine glave ličinki, korištena je višestruka nelinearna Gausova krivulja. Vrhovi normalnih krivulja bili su 227 ± 3 μm, 353 ± 6 μm i 519 ± 3 μm za prvu, drugu i treću fazu razvoja. Vrijednosti su veće od vrijednosti koje su opazili autori u sličnim studijama. Rad raspravlja o mogućem utjecaju navodnjavanja i ostalih čimbenika okoliša

    Air ambulance outcome measures using Institutes of Medicine and Donabedian quality frameworks: protocol for a systematic scoping review

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    Background: Dedicated air ambulance services provide a vital link for critically ill and injured patients to higherlevels of care. The recent developments of pre-hospital and retrieval medicine create an opportunity for airambulance providers and policy-makers to utilize a dashboard of quality performance measures to assess serviceperformance. The objective of this scoping systematic review will be to identify and evaluate the range of airambulance outcome measures reported in the literature and help to construct a quality dashboard based on ahealthcare quality framework. Methods: We will search PubMed, MEDLINE, CINAHL, Scopus, and Cochrane Database of Systematic Reviews (fromJanuary 2001 onwards). Complementary searches will be conducted in selected relevant journals. We will includesystematic reviews and observational studies (cohort, cross-sectional, interrupted time series) in critically ill orinjured patients published in English and focusing on air ambulance delivery and quality measures. Two reviewerswill independently screen all citations, full-text articles, and abstract data. The study methodological quality (or bias)will be appraised using appropriate tools. Analysis of the characteristics associated with outcome measure will bemapped and described according to the proposed healthcare quality framework. Discussion: This review will contribute to the development of an air ambulance quality dashboard designed tocombine multiple quality frameworks. Our findings will provide a basis for helping decision-making in healthplanning and policy

    ESTIMATING THE VALUE OF BT CORN: A MULTI-STATE COMPARISON

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    Bt corn offers a powerful tool to control European corn borers and some other pests. Because pest infestations and farming practices differ across the Corn Belt, economic benefits also differ. This research estimates the value of Bt corn across the Corn Belt. Results identify areas where Bt adoption is economically justified.Crop Production/Industries, Research and Development/Tech Change/Emerging Technologies,

    Dual Labor Markets: A Theory of Labor Market Segmentation

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    A growing body of empirical research has documented persistent divisions among American workers: divisions by race, sex, educational credentials, industry grouping, and so forth (F. B. Weisskoff, B. Bluestone, S. Bowles and H. Gintis, D. Gordon, 1971 and 1972, B. Harrison, M. Reich, H. Wachtel and C. Betsey, and H. Zellner). These groups seem to operate in different labor markets, with different working conditions, different promotional opportunities, different wages, and different market institutions. These continuing labor market divisions pose anomalies for neoclassical economists. Orthodox theory assumes that profit-maximizing employers evaluate workers in terms of their individual characteristics and predicts that labor market differences among groups will decline over time because of competitive mechanisms (K. Arrow). But by most measures, the labor market differences among groups have not been disappearing (R. Edwards, M. Reich, and T. Weisskopf, chs. 5, 7, 8). The continuing importance of groups in the labor market thus is neither explained nor predicted by orthodox theory. Why is the labor force in general still so fragmented? Why are group characteristics repeatedly so important in the I labor market? In this paper, we summarize an emerging radical theory of labor market segmentation; we develop the full arguments in Reich, Gordon, and Edwards. The theory argues that political and economic forces within American capitalism have given rise to and perpetuated segmented labor markets, and that it is incorrect to view the sources of segmented markets as exogenous to the economic system

    Inhibition of the Aminopeptidase from \u3cem\u3eAeromonas proteolytica\u3c/em\u3e by Aliphatic Alcohols. Characterization of the Hydrophobic Substrate Recognition Site

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    Seven aliphatic and two aromatic alcohols were tested as reporters of the substrate selectivity of the aminopeptidase from Aeromonas proteolytica (AAP). This series of alcohols was chosen to systematically probe the effect of carbon chain length, steric bulk, and inhibitor shape on the inhibition of AAP. Initially, however, the question of whether AAP is denatured in the presence of aliphatic alcohols was addressed. On the basis of circular dichroism (CD), electronic absorption, and fluorescence spectra, the secondary structure of AAP, with and without added aliphatic alcohols, was unchanged. These data clearly indicate that AAP is not denatured in aliphatic alcohols, even up to concentrations of 20% (v/v). All of the alcohols studied were competitive inhibitors of AAP with Ki values between 860 and 0.98 mM. The clear trend in the data was that as the carbon chain length increases from one to four, the Ki values increase. Branching of the carbon chains also increases the Ki values, but large bulky groups, such as that found in tert-butyl alcohol, do not inhibit AAP as well as leucine analogues, such as 3-methyl-1-butanol. The competitive nature of the inhibition indicates that the substrate and each alcohol studied are mutually exclusive due to binding at the same site on the enzyme. On the basis of EPR and electronic absorption data for Co(II)-substituted AAP, none of the alcohols studied binds to the dinuclear metallo-active site of AAP. Thus, reaction of the inhibitory alcohols with the catalytic metal ions cannot constitute the mechanism of inhibition. Combination of these data suggests that each of these inhibitors bind only to the hydrophobic pocket of AAP and, consequently, block the binding of substrate. Thus, the first step in peptide hydrolysis is the recognition of the N-terminal amino acid side chain by the hydrophobic pocket adjacent to the dinuclear active site of AAP

    Mechanistic Studies on the Aminopeptidase from \u3cem\u3eAeromonas proteolytica\u3c/em\u3e:  A Two-Metal Ion Mechanism for Peptide Hydrolysis

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    The aminopeptidase from Aeromonas proteolytica (AAP) is uncompetitively inhibited by fluoride ion at pH 8.0 with an inhibition constant (Ki) of 30 mM. Thus, fluoride inactivates AAP only after substrate binding, and only a single fluoride ion binds to AAP. On the other hand, chloride ion does not inhibit AAP up to concentrations of 2 M at pH 8.0. The pH dependence of fluoride inhibition of AAP was measured over the pH range 6.0−9.5. Between pH values of 6.0 and 9.0, fluoride ion acts as a pure uncompetitive inhibitor of AAP, and the Ki increases from 1.2 to 370 mM. From a plot of pKi vs pH, a pKa value of 7.0 ± 0.3 was extracted which corresponds to a single deprotonation process. At pH values higher than 9.0, the fluoride inhibition pattern changes to competitive. This change in inhibition pattern was attributed to a change in ionic strength or perhaps pH of the solution since fluoride ion was also found to become a competitive inhibitor of AAP at pH 8.0 in the presence of 2 M NaCl. These data, taken together with previous kinetic studies of mono- and dinuclear hydrolases with fluoride ion, suggest that a Zn(II)-bound water/hydroxide exists at the dimetal active site of AAP with a pKa of 7.0 and that this water/hydroxide acts as the active site nucleophile. The hydrolysis of l-leucine-p-nitroanilide was measured spectrophotometrically in triplicate between 25 and 85 °C at eight substrate concentrations ranging from 5 to 800 μM. From these data, Km values were derived at each temperature studied and were found to increase exponentially with increasing temperature. Moreover, the calculated Vmax values were also found to increase over this temperature range, mimicking the Km values. An Arrhenius plot was constructed from kcat values and was found to be linear over the temperature range 25−85 °C, indicating that the rate-limiting step in AAP peptide hydrolysis is product formation and does not change as a function of temperature. From the slope of the line, the activation energy (Ea) was calculated to be 36.5 kJ/mol. The enthalpy and entropy of activation at 25 °C calculated over the temperature range 298−358 K were found to be 34.0 kJ/mol and −94.2 J/(mol·K), respectively. The free energy of activation at 25 °C was found to be 62.1 kJ/mol. Combination of the available X-ray crystallographic data with the present kinetic and thermodynamic results, as well as the previously reported kinetic and spectroscopic data, has allowed a detailed catalytic mechanism for AAP to be proposed
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