Home About us Contact
|
Home About us Contact | ||
|
|
||
Time Effects (time + effects)
Selected AbstractsPhysicochemical and sensory quality of wines from red sorrel/roselle (Hibiscus sabdariffa L.) calyces: effects of pretreatments of pectolase and temperature/timeINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 4 2007Pascale Mounigan Summary The effects of pretreating red sorrel (Hibiscus sabdariffa L.) calyces on the physicochemical and sensory quality of wines were investigated. Sorrel calyces were processed at 60 °C for 3.5 h or 90 °C for 30 min at 0%, 0.5% and 1.0% w/w pectolase addition in fermentation of wines. Significant changes (P < 0.01) in all physicochemical parameters of sorrel wines were found during fermentation, but not (P > 0.05) because of temperature/time effects. Colour (P < 0.01) became redder with pectolase and on storage at 23 °C for 2 months. Significant differences (P < 0.01) were noted in sensory quality for taste and flavour, balance, duration and overall quality. Higher (P < 0.01) overall sensory quality scores were obtained for wines by pretreatment at 90 °C for 30 min (10.44,11.06/20) when compared with wines at 60 °C for 3.5 h (6.88,9.06/20). Colour of wines from 90 °C/30 min was most saturated and red than all wines and had pH 2.57 ± 0.01, 0.43 ± 0.07% citric acid, 10.53 ± 0.53 °Bx and 15.29 ± 0.71% alcohol. [source] A Methodology for Assessing Transportation Network Terrorism Risk with Attacker and Defender InteractionsCOMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 6 2010Pamela M. Murray-Tuite Decision makers need a methodology that can capture the complex attacker,defender interactions and help them understand the overall effects on the transportation system, as well as the consequences of asset failure. This article presents such a methodology, which uses probabilities of target,attack method combinations that are degree of belief based and updated using Bayes' Theorem after evidence of the attack is obtained. Monte Carlo simulation generates the probability of link capacity effects by sampling from distributions of capacity reductions due to preevent security measures, substitutions, target failure, and postevent security measures. The average capacity reduction for a particular target,attack method combination serves as an input to the traffic assignment,simulation package DYNASMART-P to determine travel time effects. The methodology is applied to a sample network based on the northern Virginia area. Results based on notional data indicated that preevent security measures reduced attack probabilities, but in some cases increased the mobility consequences. Thus, decision makers must carefully evaluate the effects of their decisions. [source] Space,time modeling of rainfall dataENVIRONMETRICS, Issue 6 2004Luis Guillermo Coca Velarde Abstract Climate variables assume non-negative values and are often measured as zero. This is just the case when the rainfall level, in the dry season, is measured in a specified place. Then, the stochastic modeling demands the inclusion of a probability mass point at the zero level, and the resulting model is a mixture of a continuous and a Bernoulli distribution. In this article, spatial conditional autoregressive effects dealing with the idea that neighbors present similar responses is considered and the response level is modeled in two stages. The aim is to consider spatial interpolation and prediction of levels in a Bayesian context. Data on weekly rainfall levels measured in different stations at the central region of Brazil, an area with two well-marked seasons, will be used as an example. A method for comparing models, based on the deviance function, is also implemented. The main conclusion is that the use of space,time models improves the modeling of hydrological and climatological variables, allowing the inclusion of real life considerations such as the influence of other covariates, space dependence and time effects such as seasonality. Copyright © 2004 John Wiley & Sons, Ltd. [source] Age,period,cohort models and disease mappingENVIRONMETRICS, Issue 5 2003Corrado Lagazio Abstract Joint modelling of space and time variation of the risk of disease is an important topic in descriptive epidemiology. Most of the proposals in this field deal with at most two time scales (age,period or age,cohort). We propose a hierarchical Bayesian model that can be used as a general framework to jointly study the evolution in time and the spatial pattern of the risk of disease. The rates are modelled as a function of purely spatial terms (local effects of risk factors that do not vary in time), time effects (on the three time axes: age, calendar period and birth cohort) and space,time interactions that describe area specific time patterns. Copyright © 2003 John Wiley & Sons, Ltd. [source] Study of the space,time effects in the concentration of airborne pollutants in the Metropolitan Region of Rio de JaneiroENVIRONMETRICS, Issue 4 2003Marina Silva Paez Abstract In this article, we present an application of models with temporal and spatial components, from the Bayesian point of view, on data pollutants collected in 16 different monitoring sites located in the Metropolitan Area of Rio de Janeiro during 1999. All the models considered here assume conditionally independent observations, with a mean specified by the sum of random temporal and spatial components and a linear function of the maximum daily temperature and indicators of the day of the week. Our aim here is to analyze distinct specifications for the components, assuming different kinds of modeling that are not usually compared. The comparison is based on the posterior predictive loss function proposed by Gelfand and Ghosh (1998). The best specifications for the spatial component were the ones which considered a geostatistical approach to its correlation function. The best specification for the temporal component was the stationary autoregressive form. The pollutant concentrations were interpolated in a grid of points in the area of higher population density at a fixed period of time for the selected model. Copyright © 2003 John Wiley & Sons, Ltd. [source] An overview of the damage approach of durability modelling at elevated temperatureFATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 6 2001J.-L. Chaboche Lifetime prediction techniques for components working at elevated temperature are revisited. Two damage approaches in which time effects at high temperature are introduced in different ways are discussed in greater detail. First, a creep,fatigue damage model considers the interaction of the two processes during the whole life before macrocrack initiation; and second, a creep,fatigue,oxidation model separates the fatigue life into two periods: during initiation the environment-assisted processes interact with fatigue, although bulk creep damage only interacts during the micropropagation period. The second model is illustrated by its application to a coated single-crystal superalloy used in aerojet turbine blades. Its capabilities are illustrated in a number of isothermal and thermomechanical fatigue tests. Anisotropy effects are also briefly discussed and a special test, introducing cyclic thermal gradients through the wall thickness of a tubular component, demonstrates the predictive capabilities for actual engine conditions. [source] Using Scanner Technology to Collect Expenditure Data,FISCAL STUDIES, Issue 3-4 2009Andrew Leicester C81; C83; C33; C41 Abstract In terms of collecting panel expenditure data, there are trade-offs between the demands imposed on respondents and the detail and coverage of data collected. Comprehensive spending data tend to be cross-sectional whilst panel studies include only limited, aggregated expenditure questions. Recently, economists have begun to use detailed, bar-code-level spending data from household panels collected by market research companies. However, there has not been a detailed assessment of the strengths and weaknesses of this collection method or its implications for the recorded data. This paper seeks to fill this gap by providing an in-depth examination of data from one company, Taylor Nelson Sofres (TNS), recording grocery purchases over five years. We assess how far the ongoing demands of participation lead to ,fatigue' in respondents' recording of their spending and the implications for household attrition, and we provide a detailed comparison of the expenditure data collected by TNS and the well-established Expenditure and Food Survey (EFS). Broadly, we suggest that problems of fatigue and attrition may not be particularly severe, though there are differences in expenditures that cannot be attributed to demographic or time effects and may be suggestive of survey mode effects. [source] Notice of Plagiarism: A Single Recovery Type Curve from Theis' Exact SolutionGROUND WATER, Issue 1 2004Article first published online: 9 OCT 200 Shortly after the September-October 2003 issue of the journal was mailed, three readers called our attention to similarities between the paper by N. Samani and M. Pasandi (2003, ?A single recovery type curve from Theis? exact solution,?Ground Water 41, no. 5: 602-607) and a paper published in 1980 by Ram G. Agarwal. Agarwal?s paper, ?A new method to account for producing time effects when drawdown type curves are used to analyze pressure buildup and other test data,? was published by the Society for Petroleum Engineers (1980, in Society of Petroleum Engineers 55th Annual Fall Technical Conference, September 2 1-24, Dallas, Texas: SPE Paper 9289). An investigation by the journal verified that the approach and some of the wording used in the two papers are identical. Dr. Samani and Mr. Pasandi acknowledge the similarity and offer an explanation and apology. [source] Temporal changes in the affective experience of new fathers and their spousesINFANT MENTAL HEALTH JOURNAL, Issue 6 2004Marsha Kaitz Our aim was to study temporal changes in fathers' affective experience during the first year of parenthood. For comparison, data also were collected from their spouses. Fifty-five Israeli couples comprised the initial sample, and both partners were interviewed during the prepartum period and at 3, 6, and 12 months' postpartum. Measures of emotionality, positive affect, negative affect, and mood regarding self, infant, and spouse/marriage were derived by finely coding parents' answers to interview questions. Analyses show that, for fathers and mothers, time effects were most substantial between the prepartum period and 3 months postpartum, and most of the changes were in a positive direction. Fathers and mothers showed continuity in positive affect and in negative affect, respectively. Overall, the sample experienced heightened positive affect and more positive moods after the birth of their infant than prior to it. [source] Adoption and Abandonment of Organic Farming: An Empirical Investigation of the Irish Drystock SectorJOURNAL OF AGRICULTURAL ECONOMICS, Issue 3 2010Doris Läpple Q12; C41; Q16 Abstract There is a considerable literature about the adoption of organic farming. However, possible abandonment of organic farming has received scant attention. Thus, relatively little is known about the exit decisions of farmers. In addition, most studies are based on a static framework where it is not possible to account for changes in farmer decisions over time. This article attempts to fill this gap in the literature by investigating the determinants that affect both adoption and abandonment of organic drystock farming over time. The use of duration analysis allows for the consideration of cross-sectional and time-varying factors over the study period from 1981 to 2008. Using this dynamic econometric framework revealed a significant time effect on entry and exit decisions. Overall, the results highlight that where no attempt is made to account for exit decisions and time effects, important information about sustainable farmer decisions may not be taken into consideration. [source] Predator behaviour and prey density: evaluating density-dependent intraspecific interactions on predator functional responsesJOURNAL OF ANIMAL ECOLOGY, Issue 1 2001Nilsson P. Anders Abstract 1In models of size-structured predator,prey systems, the effects are evaluated of gape-size limited predation on prey population growth and density when predators are non-interacting, cannibalistic, interfering, and cannibalistic and interfering. 2Predation from non-interacting predators markedly reduces prey density, compared with prey densities in the absence of predation. When density-dependent cannibalism between predators is introduced, predator density and therefore total functional response decrease, resulting in a decrease in predation pressure and higher prey densities. 3Size- and density-dependent interference between predators substantially decreases functional responses in the predators, and the prey population is thus allowed to grow more dense. Allowing for cannibalism between interfering predators also decreases predator density, but here the decreased number of predators does not have the releasing effect seen in solely cannibalistic predators. The interference between predators decreases with predator density, and per capita functional responses increase and compensate for the decrease in predator density. 4These theoretical results are compared with results from natural systems with pikeperch and northern pike. Both species are cannibalistic, and pike are also kleptoparasitic, mirroring the models. Results from introductions of the different piscivores into natural systems corroborate the outcome of the models, since introduction or increased densities of pikeperch have shown to have severe and long-lasting effects on prey, while pike have only initial, decreasing over time effects on prey stock. Thus, predator behaviour may seriously affect predator impact on prey, and size- and density-dependent interactions between predators may be a major key to the understanding of predator,prey dynamics and community composition in lakes. [source] Association of Season and Pasture Grazing with Blood Hormone and Metabolite Concentrations in Horses with Presumed Pituitary Pars Intermedia DysfunctionJOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 5 2010N. Frank Background: Pituitary pars intermedia dysfunction (PPID) is a risk factor for pasture-associated laminitis, which follows a seasonal pattern. Hypothesis: Hormonal responses to season differ between PPID and unaffected horses. Animals: Seventeen horses aged 8,30 years (14 horses , 20 years of age). Methods: Longitudinal observational study. Blood was collected monthly from August 2007 until July 2008 after pasture grazing and again after overnight stall confinement. Blood hormone and metabolite concentrations were measured and pasture grass samples were analyzed to determine carbohydrate content. Analysis of variance analysis for repeated measures was performed. Results: Mean ACTH concentrations varied significantly over time (P < .001), with higher concentrations detected in August, September, and October compared with November,April. Pasture × time effects were detected for glucose and insulin concentrations, with peaks observed in September. Horses were retrospectively allocated to PPID (n = 8) and control (n = 9) groups on the basis of plasma ACTH concentrations. Changes in insulin concentrations over time differed in the PPID group when compared with the control group. Insulin concentrations were positively correlated with grass carbohydrate composition. Conclusions and Clinical Importance: PPID did not affect the timing or duration of the seasonal increase in ACTH concentrations, but higher values were detected in affected horses. Insulin concentrations differed between groups, but hyperinsulinemia was rarely detected. Glucose and insulin concentrations peaked in September when horses were grazing on pasture, which could be relevant to the seasonal pattern of laminitis. [source] Functional perfusion imaging using continuous arterial spin labeling with separate labeling and imaging coils at 3 TMAGNETIC RESONANCE IN MEDICINE, Issue 5 2003Toralf Mildner Abstract Functional perfusion imaging with a separate labeling coil located above the common carotid artery was demonstrated in human volunteers at 3 T. A helmet resonator and a spin-echo echo-planar imaging (EPI) sequence were used for imaging, and a circular surface coil of 6 cm i.d. was employed for labeling. The subjects performed a finger-tapping task. Signal differences between the condition of finger tapping and the resting state were between ,0.5% and ,1.1 % among the subjects. The imaging protocol included a long post-label delay (PLD) to reduce transit time effects. Labeling was applied for all repetitions of the functional run to reduce the sampling interval. Magn Reson Med 49:791,795, 2003. © 2003 Wiley-Liss, Inc. [source] Validation and advantages of FAWSETS perfusion measurements in skeletal muscleNMR IN BIOMEDICINE, Issue 4 2005Kenneth I. Marro Abstract This work discusses the strengths, limitations and validity of a novel arterial spin labeling technique when used specifically to measure perfusion in limb skeletal muscle. The technique, flow-driven arterial water stimulation with elimination of tissue signal (FAWSETS), offers several advantages over existing arterial spin labeling techniques. The primary goal of this study was to determine the perfusion signal response to changes in net hind limb flow that were independently verifiable. The range of perfusate flow was relevant to skeletal muscle during mild to moderate exercise. Localized, single voxel measurements were acquired from a 5,mm-thick slice in the isolated perfused rat hind limb at variable net flow rates. The results show that the perfusion signal is linearly proportional to net hind limb flow with a correlation coefficient of 0.974 (p,=,0.0013). FAWSETS is especially well suited for studies of skeletal muscle perfusion, where it eliminates the need to compensate for magnetization transfer and arterial transit time effects. A conceptual discussion of the basic principles underlying these advantages is presented. Copyright © 2005 John Wiley & Sons, Ltd. [source] Protective effect of BR-16A, a polyherbal preparation against social isolation stress: possible GABAergic mechanismPHYTOTHERAPY RESEARCH, Issue 7 2006Anil Kumar Abstract The antistress effects of BR-16A, a polyherbal preparation and its interaction with GABAergic modulators against social isolation-induced stress were investigated in the present study. Isolation stress was induced by keeping the mice (Laca strain) individually in each cage for 3 weeks and various drug treatments were given for a period of 5 days before the start of the experiments. The various behavioural parameters examined included pentobarbitone-induced sleep (sleep latency and duration), analgesia (tail-ßick test) and locomotor activity, respectively. BR-16A (100 mg/kg and 200 mg/kg) treatment for 5 days significantly reversed the social isolation stress-induced prolongation of onset and decrease in pentobarbitone-induced sleep, increased total motor activity and stress-induced antinociception. When diazepam (0.5 mg/kg), a benzodiazepine agonist, was co-administered with BR-16A (100 mg/kg), it significantly potentiated the reversal of pentobarbitone-induced shortening of sleep time effects; increased locomotor activity and stress induced antinociceptive effects. However, the sleep latency was not decreased significantly. Further, ßumazenil (2 mg/kg), a benzodiazepine receptor antagonist and FG 7142 (10 mg/kg), an inverse agonist, when co-administered with BR-16A (100 mg/kg), showed no significant reversal on pentobarbitone-induced hypnosis, locomotor activity and social isolation-induced antinociception compared with their effects per se. The present study demonstrated the antistress effects of BR-16A preparation against social isolation-induced stress. The present study also suggests that the GABAergic system may be involved in its antistress effect. Copyright © 2006 John Wiley & Sons, Ltd. [source] Sowing density and harvest time affect fibre content in hemp (Cannabis sativa) through their effects on stem weightANNALS OF APPLIED BIOLOGY, Issue 2 2009W. Westerhuis Abstract Sowing density and harvest time are considered important crop management factors influencing fibre quantity and quality in hemp (Cannabis sativa). We investigated whether the effects of these factors are essentially different or that both factors affect stem weight and thereby total and long-fibre content. The effects of all combinations of three sowing densities and three harvest times were studied for six different stem parts. Almost 500 samples consisting of stem parts from 50 plants and with a length of 50 cm were tested. Fibres were extracted by a controlled warm-water retting procedure, followed by breaking and scutching. The initial sample weight was fractionated into retting losses, wood, tow and long fibre. In both Italy and the Netherlands, crops were successfully established with different stem densities (99,283 m,2), plant heights (146,211 cm) and stem diameters (4.5,8.4 mm) at harvest. Stem dry matter yields (6.8,11.7 Mg ha,1) increased with a delay in harvest time but were not affected by sowing density. Retting loss percentages were lower in lower stem parts and decreased with later harvest because maturation was associated with increasing amounts of fibre and wood. Within a certain stem part, however, the absolute retting losses were constant with harvest time. Multiple linear regression analyses showed that the amount of fibre in a hemp stem is almost completely determined by the weight and the position of that stem part. When the plant grows, the increase in dry matter is split up into fibres and wood in a fixed way. This total fibre/wood ratio was highest in the middle part of the stem and lower towards both bottom and top. Sowing density and harvest time effects were indirect through stem weight. The long-fibre weight per stem increased with the total fibre weight and hence with stem weight. Stem weight increased with harvest time; as harvest time did not affect plant density, the highest long-fibre yields were obtained at the last harvest time. The long fibre/total fibre ratio was lowest in the bottom 5 cm of the stems but similar for all other parts. Sowing density and harvest time effects again were indirect. Fibre percentages in retted hemp decreased with increasing stem weights towards a level that is presumably a variety characteristic. The dry matter increase between harvests, however, is much more important with respect to total and long-fibre yield. [source] | |||||||||||||||||||