1,356 research outputs found
Social inclusion implications of park-and-ride
Park and ride (P&R) schemes are often promoted as an efficient means of extending the effective catchment of public transport networks into car-dependent areas with low population densities, such as rural districts. However, using P&R typically requires the traveller to have access to a car. As car ownership is often used as an indicator of social inclusion, providing P&R for motorists is not an obvious means of reducing exclusion from travel opportunities. Nonetheless, the present article argues that policies to promote interchange from cars to bus or rail can act as a force for either greater or less social exclusion, depending on who can access the services and what the alternative options would be in the absence of P&R being provided. The conditions under which inclusion is most likely to be promoted are reviewed. Key findings are that P&R facilities should not be developed at the expense of investment in conventional public transport and that the services should not be exclusively aimed at motorists. A particular situation in which motorists on relatively low incomes might benefit from P&R provision is where they would otherwise face high access charges to urban areas, in the form of road tolls or parking fees
The Influence of Positive and Negative Framed Information Load: An Experimental Investigation
The purpose of this paper is to test the effect of three information attributesāthe framing of information as positive or negative, the symmetry and non-symmetry of information sets, and the quantity of information on individual choicesāwhen choosing between two lotteries. The main effects from a random effects probit model indicate that the quantity of information and symmetry of information influence individual choices over lotteries. When presented with negative information, individuals exhibit less switching behavior between two lotteries. One possible explanation for our result is that a negativity bias is present when information is framed negative which causes individuals to behave differently across lotteries regardless of the quantity of information
Synthesis of poly(sulfonate ester)s by ADMET polymerization
Many hydrocarbon polymers containing heteroatom defects in the main chain have been investigated as degradable polyethylene-like materials, including aliphatic polyesters. Here, acyclic diene metathesis (ADMET) polymerization was used for the synthesis of aliphatic poly(sulfonate ester)s. The requisite sulfonate ester containing Ī±,Ļ-diene monomers with varying numbers of methylene groups were synthesized, and their polymerization in the presence of ruthenium-N-heterocyclic (Ru-NHC) alkylidene catalysts was studied. A clear negative neighboring group effect (NNGE) was observed for shorter dienes, either inhibiting polymerization or resulting in low- molecular-weight oligomers. The effect was absent when undec-10-en-1-yl undec-10- ene-1-sulfonate was employed as the monomer, and its ADMET polymerization afforded polymers with appreciable number-average molecular weights of up to 37,000 g/mol and a dispersity Ä of 1.8. These polymers were hydrogenated to afford the desired polyethylene-like systems. The thermal and morphological properties of both saturated and unsaturated polymers were investigated. The incorporation of sulfonate ester groups in the polymer backbone offers an interesting alternative to other heteroatoms and helps further the understanding of the effects of these defects on the overall polymer properties
USING NONLINEAR FIXED AND MIXED MODELS WITH SWITCHING FUNCTIONS TO ALLOW FOR HORMESIS IN GROWTH OF ESCHERICHIA COLI
Individual Escherichia coli (E. coli) strains can be characterized by measuring growth rate. Strains better adapted to the environment are expected to grow faster. Classic bacterial growth curves display an increase in optical density over time. In this paper, we use the logistic function to model growth in optical density of E. coli over time. We examine 16 curves for 8 E. coli strains originally isolated from cattle and found many curves have a paradoxical dip at the beginning that is indicative of hormesis (an initial contrarian response showing, stimulation or suppression of growth). We examine several switching functions that allow for the effect of hormesis and compare the ability of nonlinear fixed and mixed models to detect the presence of hormesis
MODELING THE BODY TEMPERATURE OF HEAT STRESSED HOLSTEIN LYING COWS UNDER TWO DIFFERENT COOLING PROCESSES
Heat stressed cows produce less milk. Thus, a major challenge during hot summer months is to keep the dairy barn at a comfortable temperature. Use of fans is an economical solution but the combination of both spray and fans appears to be an even more effective way to cool cows and improve the milk production than using fans alone. The goal of this study is to recommend an appropriate method for comparing the dynamics of the cooling processes. The first step is to develop a nonlinear model to characterize the thermoregulatory responses of heat stressed dairy cows when they are lying down. The next step is to evaluate methods of comparing treatment effects such as mixed model analysis of the parameter estimates, nonlinear fixed effects analysis, and nonlinear mixed effects analysis. The final step is to illustrate the recommended analysis
NONLINEAR MIXED MODELS TO EVALUATE EFFECTS OF ENVIRONMENT CONDITIONS, HAIR COAT, AND ANCHOR LENGTH ON BODY TEMPERATURE DURING AFTERNOON MILKING OF HOLSTEIN COWS IN HAWAII
A hot thermal environment is one factor that causes loss of activity, productivity and even death in cows. One reason may be the effect of hair coat (black or white) on body temperature during different activities and environment conditions. In this study, we attempt to characterize the relationship between body temperature over time using activity, physiological and environmental effects with a nonlinear regression model. The fixed and mixed versions of models are examined. We also examine the effect of the measuring device, anchor length (long or short). Environmental effects, such as, air temperature, thermal heat index (THI), relative humidity, solar radiation, and wind speed, For PM Milking activity, differences in hair coat and anchor length tested as treatment effects. We present a detailed approach focusing on the rate of change in animal body temperature using the nonlinear regression model and investigate how the dynamics between the random-effects changes
ESTIMATING RHEOLOGICAL PROPERTIES OF YOGURT USING DIFFERENT VERSIONS OF THE FREUNDLICH MODEL AND DESIGN MATRICES
The rheological properties described by the consistency coefficient and flow behavior index can be estimated from the relationship between shear stress and shear strain rate following a Freundlich model. An additional rheological property of concern to food scientists studying yogurt is yield stress. They extend the Freundlich model to include a three-parameter model called the Herschel-Bulkley model. In addition, the Herschel-Bulkley model is often linearized by taking logarithms of both sides. An additional complication is the viscometer limits the range of shear strain rates. The objectives of this study are to compare parameter estimates from the three models and to investigate the effects of different designs on the models
USING A NONLINEAR CROSSED RANDOM EFFECTS MODEL WITH THREE-WAY TREATMENT STRUCTURE FOR DESCRIBING CIRCADIAN PATTERNS OF SERUM PROLACTIN CONCENTRATIONS IN HEAT STRESSED HOLSTEINS
A modified Gaussian model with three-level crossed and nested random effects is used to describe circadian patterns of serum prolactin concentrations in a crossover experiment. Testing of three-way treatment effects and carryover effects are incorporated with the model building process as is the within-group correlation. We found that the interaction between environment and parity had significant effect (p\u3c0.05) on both initial serum prolactin concentration and range of the prolactin concentration. There was no significant effect of recombinant bovine somatotropin (rbST) on either the initial value or concentration of serum prolactin. The inclusion of carryover effects in the model significantly improves the fit of the multilevel nonlinear mixed effects model. We present in detail a general approach to nonlinear crossed random effects model building and three-way treatment effects testing
The association of NADPH with the guanine nucleotide exchange factor from rabbit reticulocytes: A role of pyridine dinucleotides in eukaryotic polypeptide chain initiation
The guanine nucleotide exchange factor (GEF) was purified to apparent homogeneity from postribosomal supernatants of rabbit reticulocytes by chromatography on DEAE-celiulose and phosphocellulose, fractionation by glycerol gradients, and chromatography on Mono S and Mono Q (Pharmacia). At the Mono S step GEF is isolated as a complex with the eukaryotic polypeptide chain initiation factor 2 (eIF-2) and is separated from this factor by column chromatography on Mono Q. An emission spectrum characteristic of a reduced pyridine dinucleotide was observed when GEF was subjected to fluorescence analysis. By both coupled enzymatic analysis and chromatography on reverse-phase or Mono Q columns, the bound dinucleotide associated with GEF was determined to be NADPH. The GEF-catalyzed exchange of eIF-2-bound GDP for GTP was markedly inhibited by NAD+ and NADP+. This inhibition was not observed in the presence of equimolar concentrations of NADPH. Similarly, the stimulation of ternary complex (eIF-2ā¢GTPā¢Met-tRNAf) formation by GEF in the presence of 1 mM Mg2+ was abolished in the presence of oxidized pyridine dinucleotide. These results demonstrate that pyridine dinucleotides may be directly involved in the regulation of polypeptide chain initiation by acting as allosteric regulators of GEF activity
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