Stochastic frontier regression is used to examine the effect of introducing prevailing wage legislation on public school construction efficiency in British Columbia. Prior to the legislation, public school projects were from 16% to 19% smaller, in terms of square feet, than comparable private structures. However, likelihood ratio tests consistently indicate that the coefficients measuring the effect of the policy on the size differential between covered and uncovered projects are not statistically different from zero. These results suggest that construction wage requirements did not alter input utilisation in a way that significantly affected construction output. Average inefficiency for school construction in British Columbia over the period of the study is 12.1%. 相似文献
A pressurized melt gyration process has been used for the first time to generate poly(ε‐caprolactone) (PCL) fibers. Gyration speed, working pressure, and melt temperature are varied and these parameters influence the fiber diameter and the temperature enabled changing the surface morphology of the fibers. Two types of nonwoven PCL fiber constructs are prepared. First, Ag‐doped PCL is studied for antibacterial activity using Gram‐negative Escherichia coli and Pseudomonas aeruginosa microorganisms. The melt temperature used to make these constructs significantly influences antibacterial activity. Neat PCL nonwoven scaffolds are also prepared and their potential for application in muscular tissue engineering is studied with myoblast cells. Results show significant cell attachment, growth, and proliferation of cells on the scaffolds.
This paper examines how Wellbeing Toronto (WT)—a free, open data, GIS tool that allows users to map information—has evolved into an extensive data repository with robust data analysis capabilities. Explored is the progress of open data scholarship in relation to municipal government and civic participation. Based on this, the authors note the following: (1) as open data becomes increasingly prevalent, a more varied understanding of the organization and structure of municipal government may emerge. (2) There is a need for measures of civic engagement to move beyond data co-production towards an organization-based interactive approach. 相似文献
The accurate establishment and maintenance of DNA methylation patterns is vital for mammalian development and disruption to these processes causes human disease. Our understanding of DNA methylation mechanisms has been facilitated by mathematical modelling, particularly stochastic simulations. Megabase-scale variation in DNA methylation patterns is observed in development, cancer and ageing and the mechanisms generating these patterns are little understood. However, the computational cost of stochastic simulations prevents them from modelling such large genomic regions. Here, we test the utility of three different mean-field models to predict summary statistics associated with large-scale DNA methylation patterns. By comparison to stochastic simulations, we show that a cluster mean-field model accurately predicts the statistical properties of steady-state DNA methylation patterns, including the mean and variance of methylation levels calculated across a system of CpG sites, as well as the covariance and correlation of methylation levels between neighbouring sites. We also demonstrate that a cluster mean-field model can be used within an approximate Bayesian computation framework to accurately infer model parameters from data. As mean-field models can be solved numerically in a few seconds, our work demonstrates their utility for understanding the processes underpinning large-scale DNA methylation patterns. 相似文献
Lysophosphatidic acid (lysoPtdOH) levels have previously been reported to decrease in rodents with short-term fasting. We investigated whether a 16 h fast would change expression of autotaxin, the predominant phospholipase D responsible for adipose-derived lysoPtdOH synthesis, or any of the lysophosphatidic acid receptors (1–6) in four white adipose tissue (WAT) depots and interscapular brown adipose tissue (BAT) in male C57Bl/6J mice fed ad libitum, or fasted for 16 h. Aside from small inductions of Lpar1 in epididymal WAT and Lpar2 in epididymal and inguinal WAT, no significant changes were observed in expression of the Lpar family members, or autotaxin in perirenal, retroperitoneal, epididymal, or inguinal WAT or BAT with fasting. Comparison of the relative expression of Lpar1-6 in various depots showed that Lpar6 was the predominant Lpar in both WAT and BAT, and suggests that further work on the adipose-specific role of Lpar6 is warranted. 相似文献
The effect of micro-architectural structure of cabbage (Brassica oleracea var. capitata L.) substratum and or background bacterial flora on the growth of Listeria monocytogenes as a function of incubation temperature was investigated. A cocktail mixture of Pseudomonas fluorescens, Pantoea agglomerans and Lactobacillus plantarum was constituted to a population density of approximately 5 log CFU/ml in order to pseudo-simulate background bacterial flora of fresh-cut cabbage. This mixture was co-inoculated with L. monocytogenes (approximately 3 log CFU/ml) on fresh-cut cabbage or in autoclaved cabbage juice followed by incubation at different temperatures (4-30 degrees C). Data on growth of L. monocytogenes were fitted to the primary growth model of Baranyi in order to generate the growth kinetic parameters of the pathogen. During storage, microbial ecology was dominated by P. fluorescens and L. plantarum at refrigeration and abuse temperature, respectively. At all temperatures investigated, lag duration (lambda, h), maximum specific growth rate (micro(max), h(-1)) and maximum population density (MPD, log CFU/ml) of L. monocytogenes were only affected by medium micro-architectural structure, except at 4 degrees C where it had no effect on the micro(max) of the pathogen. Comparison of observed values of micro(max) with those obtained from the Pathogen Modelling Program (PMP), showed that PMP overestimated the growth rate of L. monocytogenes on fresh-cut cabbage and in cabbage juice, respectively. Temperature dependency of micro(max) of L. monocytogenes, according to the models of Ratkowsky and Arrhenius, showed linearity for temperature range of 4-15 degrees C, discontinuities and linearity again for temperature range of 20-30 degrees C. The results of this experiment have shown that the constituted background bacterial flora had no effect on the growth of L. monocytogenes and that micro-architectural structure of the vegetable was the primary factor that limited the applicability of PMP model for predicting the growth of L. monocytogenes on fresh-cut cabbage. A major limitation of this study however is that nutrient profile of the autoclaved cabbage juice may be different from that of the raw juice thus compromising realistic comparison of the behaviour of L. monocytogenes as affected by micro-architectural structure. 相似文献