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Time Used (time + used)
Selected AbstractsRadio-tracking gravel particles in a large braided river in New Zealand: a field test of the stochastic theory of bed load transport proposed by EinsteinHYDROLOGICAL PROCESSES, Issue 3 2001H. M. Habersack Abstract Hans A. Einstein initiated a probabilistic approach to modelling sediment transport in rivers. His formulae were based on theory and were stimulated by laboratory investigations. The theory assumes that bed load movement occurs in individual steps of rolling, sliding or saltation and rest periods. So far very few attempts have been made to measure stochastic elements in nature. For the first time this paper presents results of radio-tracing the travel path of individual particles in a large braided gravel bed river: the Waimakariri River of New Zealand. As proposed by Einstein, it was found that rest periods can be modelled by an exponential distribution, but particle step lengths are better represented by a gamma distribution. Einstein assumed an average travel distance of 100 grain-diameters for any bed load particle between consecutive points of deposition, but larger values of 6·7 m or 150 grain-diameters and 6·1 m or 120 grain-diameters were measured for two test particle sizes. Together with other available large scale field data, a dependence of the mean step length on particle diameter relative to the D50 of the bed surface was found. During small floods the time used for movement represents only 2·7% of the total time from erosion to deposition. The increase in percentage of time being used for transport means that it then has to be regarded in stochastic transport models. Tracing the flow path of bed load particles between erosion and deposition sites is a step towards explaining the interactions between sediment transport and river morphology. Copyright © 2001 John Wiley & Sons, Ltd. [source] The effect of low-temperature blanching on the quality of fresh and frozen/thawed mashed potatoesINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 5 2006Cristina Fernández Summary The effect of low-temperature blanching (LTB) prior to cooking on colour, textural, firmness and oscillatory parameters, sensory attributes and overall acceptability of either fresh or frozen/thawed mashed potatoes was studied using response surface methodology (RSM) to establish the optimum temperature and time for blanching in both types of mashed potatoes. A central composite rotatable design was used to study the effects of variation in levels of blanching temperature (57.93,72.07 °C) and time (15.86,44.14 min) on the quality parameters. Stationary points showing maximum thickening had critical temperatures (approximately 67,69 °C) and times (approximately 26,30 min) in the ranges of temperature and time used for each independent variable for both fresh and frozen/thawed mashed potato. Results showed a high correlation between structural reinforcement and overall acceptability under optimum experimental blanching conditions. This demonstrates the potential of this experimental approach in terms of tailoring physical properties to predetermined levels in order to meet consumer preferences in mashed potatoes, and of altering the changes that occur after freezing and thawing. [source] Breeding in high-elevation habitat results in shift to slower life-history strategy within a single speciesJOURNAL OF ANIMAL ECOLOGY, Issue 2 2009H. Bears Summary 1Elevational gradients create environmental variation that is hypothesized to promote variation in life-history strategies. We tested whether differences in life-history strategies were associated with elevation in a songbird, the dark-eyed junco (Junco hyemalis; Aves; A.O.U. 1998). 2We monitored birds in four replicated sites per elevation, at 2000 m a.s.l. (high elevation) and 1000 m a.s.l. (low elevation), in the Rocky Mountains of Canada. 3Over 5 years, we measured the following traits and vital rates: egg-laying schedules, morphological indicators of reproductive stage, seasonal reproductive success, indicators of competitive class (age, size, arrival time), and survival rates. 4We found two main patterns: with an increase in breeding elevation, dark-eyed juncos delayed the development of structures necessary for reproduction (e.g. cloacal protuberance in males) and reduced the duration of their reproductive period to less than half of the time used by low-elevation birds; and 5Juncos at high-elevation sites had 55,61% lower annual reproductive success and 15 to 20% higher survival rates. While adult juncos at high elevations produced fewer offspring, those offspring were in better condition. Proportions of age and size classes in high- compared to low-elevation populations were similar, suggesting that a life-history trade-off is present, rather than competition forcing inferior competitors to breed in a peripheral habitat. The apparent trade-off between reproduction and survival corresponded to a shorter period of favourable weather and available food in high- compared to low-elevation habitats. 6Thus, elevation had a strong influence on life-history characteristics of a single species over a short spatial distance, suggesting a shift in life history from a high reproductive strategy at lower elevations to a high survivor strategy at high elevations. 7This is the first paper to show a shift in avian life-history strategies along an elevational gradient (in both genders, of multiple age classes) when region (latitude) and phylogenetic histories are controlled for. [source] Trends of the bonding effect on the performance of DFT methods in electric properties calculations: A pattern recognition and metric space approach on some XY2 (X = O, S and Y = H, O, F, S, Cl) moleculesJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 2 2010Christos Christodouleas Abstract A test set of 10 molecules (open and ring forms of ozone and sulfur dioxide as well as water and hydrogen sulfide and their respective fluoro- and chloro-substituted analogs) of specific atmospheric interest has been formed as to assess the performance of various density functional theory methods in (hyper)polarizability calculations against well-established ab initio methods. The choice of these molecules was further based on (i) the profound change in the physics between isomeric systems, e.g., open (C2v) and ring (D3h) forms of ozone, (ii) the relation between isomeric forms, e.g., open and ring form of sulfur dioxide (both of C2v symmetry), and (iii) the effect of the substitution, e.g., in fluoro- and chloro-substituted water analogs. The analysis is aided by arguments chosen from the information theory, graph theory, and pattern recognition fields of Mathematics: In brief, a multidimensional space is formed by the methods which are playing the role of vectors with the independent components of the electric properties to act as the coordinates of these vectors, hence the relation between different vectors (e.g., methods) can be quantified by a proximity measure. Results are in agreement with previous studies revealing the acceptable and consistent behavior of the mPW1PW91, B3P86, and PBE0 methods. It is worth noting the remarkable good performance of the double hybrid functionals (namely: B2PLYP and mPW2PLYP) which are for the first time used in calculations of electric response properties. © 2009 Wiley Periodicals, Inc. J Comput Chem 2010 [source] EVALUATION OF LENTIL TEXTURE MEASUREMENTS BY COMPRESSION TESTINGJOURNAL OF TEXTURE STUDIES, Issue 4 2000S. D. ARNTFIELD ABSTRACT The variability in texture for lentils of different size, from different locations and cooked for varying lengths of time was examined in relation to the sample size and the extent to which the sample was compressed during testing. The force to compress the lentils was found to be dependent on all variables examined and also demonstrated significant interactions between these variables. The coefficient of variability was dependent on the size of the lentil, a two-way interaction between sample size and compression and a three-way interaction between location, cooking time and sample size. Regardless of lentil size, location where the lentil was grown and the cooking time used, the variability in the texture readings was lowest when the larger sample size and maximum compression force were used. [source] Model choice in time series studies of air pollution and mortalityJOURNAL OF THE ROYAL STATISTICAL SOCIETY: SERIES A (STATISTICS IN SOCIETY), Issue 2 2006Roger D. Peng Summary., Multicity time series studies of particulate matter and mortality and morbidity have provided evidence that daily variation in air pollution levels is associated with daily variation in mortality counts. These findings served as key epidemiological evidence for the recent review of the US national ambient air quality standards for particulate matter. As a result, methodological issues concerning time series analysis of the relationship between air pollution and health have attracted the attention of the scientific community and critics have raised concerns about the adequacy of current model formulations. Time series data on pollution and mortality are generally analysed by using log-linear, Poisson regression models for overdispersed counts with the daily number of deaths as outcome, the (possibly lagged) daily level of pollution as a linear predictor and smooth functions of weather variables and calendar time used to adjust for time-varying confounders. Investigators around the world have used different approaches to adjust for confounding, making it difficult to compare results across studies. To date, the statistical properties of these different approaches have not been comprehensively compared. To address these issues, we quantify and characterize model uncertainty and model choice in adjusting for seasonal and long-term trends in time series models of air pollution and mortality. First, we conduct a simulation study to compare and describe the properties of statistical methods that are commonly used for confounding adjustment. We generate data under several confounding scenarios and systematically compare the performance of the various methods with respect to the mean-squared error of the estimated air pollution coefficient. We find that the bias in the estimates generally decreases with more aggressive smoothing and that model selection methods which optimize prediction may not be suitable for obtaining an estimate with small bias. Second, we apply and compare the modelling approaches with the National Morbidity, Mortality, and Air Pollution Study database which comprises daily time series of several pollutants, weather variables and mortality counts covering the period 1987,2000 for the largest 100 cities in the USA. When applying these approaches to adjusting for seasonal and long-term trends we find that the Study's estimates for the national average effect of PM10 at lag 1 on mortality vary over approximately a twofold range, with 95% posterior intervals always excluding zero risk. [source] Effect of thermal processing on genistein, daidzein and glycitein content in soymilkJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 7 2006Huihua Huang Abstract Soymilk was subjected to various heat treatments at 95, 121 and 140 °C for various lengths of time. The contents of the aglycones of isoflavone (daidzein, glycitein and genistein) of the soymilk were determined using C18 reversed-phase high-performance liquid chromatography. Genistein showed greater stability to heat treatment than daidzein and glycitein. Both the daidzein and glycitein contents decreased rapidly during the early stage of heating, but on continued heating the rates of decrease were much slower. Heating may cause an increase or decrease in the genistein content of soymilk depending on the temperature and time used. Upon heating at 95 and 121 °C, there was an increase in the genistein content in the early stage of heating, possibly due the conversion of genistin to genistein. Heating at 140 °C for more than 15 s and prolonged heating at 95 and 121 °C, however, caused a slow decline in the genistein content. Copyright © 2006 Society of Chemical Industry [source] Stability of the activated partial thromboplastin time used to monitor unfractionated heparinJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 10 2008M. RAY [source] Atorvastatin in dyslipidaemia of the nephrotic syndromeNEPHROLOGY, Issue 2 2003Pedro VALDIVIELSO SUMMARY: The combined dyslipidaemia that accompanies the nephrotic syndrome increases the cardiovascular risk and appears to worsen long-term renal function. Our aim was to determine the efficacy and safety of 10 mg atorvastatin in the control of dyslipidaemia in these patients. We carried out a prospective, open, 6 month study of 10 patients with primary or secondary nephrotic syndrome (proteinuria >3.5 g/day, hypoalbuminaemia, oedema and hyperlipidaemia). The changes in lipids and plasma lipoproteins were measured, as well as the safety profile (transaminases, creatine phosphokinase, fibrinogen and antithrombin III activity) and parameters of renal function. The addition of 10 mg atorvastatin daily for 6 months resulted in a 41% reduction in low density lipoprotein (LDL) cholesterol and 31% in triglycerides (both P < 0.05), and a 15% increase in high density lipoprotein (HDL) cholesterol (NS). The drug was well tolerated and there was no change in the safety profile or deterioration in renal function. In fact, the levels of proteinuria fell in all but one patient (6.2 ± 2.6 vs 4.8 ± 2.5 g/24 h; P < 0.05). Atorvastatin, at the above dose, and for the time used proved to be a safe drug that effectively reduced dyslipidaemia in patients with nephrotic syndrome. [source] Numerical computation of a singular-state subarc in an economic optimal control modelOPTIMAL CONTROL APPLICATIONS AND METHODS, Issue 4 2006H. J. Oberle Abstract In this paper, optimal control problems (OCP) are considered which are characterized by a nonsmooth-state differential equation. More precisely, it is assumed that the right-hand side of the state equation is piecewise smooth and that the junction points between smooth subarcs are determined as roots of a state-dependent switching function. For this kind of OCP necessary conditions are developed. Special attention is paid to the situation that the switching function vanishes identically along a nontrivial subarc. Such subarcs, which are called singular-state subarcs, are investigated with respect to the necessary conditions and to the junction conditions. In this paper, we assume that the switching function is of first order with respect to the control. The theory is applied to an economic optimal control model due to Pohmer (Mikroökonomische Theorie der personellen Einkommens- und Vermögensverteilung. Studies in Contemporary Economics, vol. 16. Springer: Berlin, 1985), which describes the personal income distribution of a typical consumer, who wants to maximize the total utility of his lifetime by controlling the consumption, the rate of the total time used for working, and the rate of working time used for education and extended professional training. The state variables are the human capital and the capital itself. The utility function contains different parts which represent the influence of consumption, time of recreation, and human capital. Into this problem a parameter enters which describes the interest rate of capital. It is obvious that this parameter in general will differ for positive and negative values of the capital. Thus, the resulting OCP in a natural way becomes a nonsmooth one. For this problem, the necessary conditions are derived and numerical solutions are presented which are obtained by an indirect optimal control method. It turns out that for a certain distance of the positive and negative interest rate, the optimal solution contains a singular-state subarc. Copyright © 2006 John Wiley & Sons, Ltd. [source] Implementation of new working methods in the floor-laying trade: Long-term effects on knee load and knee complaintsAMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 6 2010Lilli Kirkeskov Jensen MD Abstract Background This study compared floor laying using new working methods involving standing up, to the traditional methods involving working on one's knees. Methods The study group, 216 subjects, completed a training class in the use of the new floor-laying methods, and received free tools and advice in their use. The control group, 454 subjects, did not get any training, but were free to use the new methods if they wished. In a 2-year-follow-up the effects were evaluated by questionnaires and by in-depth interviews of industry representatives. Regression analysis was used to control for age, body mass index (BMI), and self-reported stress. The quality of the work and time used to perform it comparing the new methods and the traditional methods was evaluated. Results Two years after the training, 38% of participants in the study group used the new working methods weekly or daily compared with 16% of the control group. The risk was at least double for serious knee complaints among floor layers who had not used the new working methods. There were no increased risks for other musculoskeletal complaints involving any other part of the body associated with the use of the new method. Conclusions Within a 2-year time period, the introduction of new working methods in the floor-laying trade has succeeded. More efforts are needed to sustain the use of the methods among those workers who have been trained and to introduce the methods to those workers who do not yet use them. Am. J. Ind. Med. 53: 615,627, 2010. © 2010 Wiley-Liss, Inc. [source] Determinants of force rise time during isometric contraction of frog muscle fibresTHE JOURNAL OF PHYSIOLOGY, Issue 3 2007K. A. P. Edman Force,velocity (F,V) relationships were determined for single frog muscle fibres during the rise of tetanic contraction. F,V curves obtained using isotonic shortening early in a tetanic contraction were different from those obtained at equivalent times with isovelocity shortening, apparently because changing activation early in the contraction leads, in isovelocity experiments, to changing force and changing series elastic extension. F,V curves obtained with isotonic and with isovelocity shortening are similar if the shortening velocity in the isovelocity trials is corrected for series elastic extension. There is a progressive shift in the scaling of force,velocity curves along the force axis during the course of the tetanic rise, reflecting increasing fibre activation. The time taken for F,V curves to reach the steady-state position was quite variable, ranging from about 50 ms after the onset of contraction (1,3°C) to well over 100 ms in different fibres. The muscle force at a fixed, moderately high shortening velocity relative to the force at this velocity during the tetanic plateau was taken as a measure of muscle activation. The reference velocity used was 60% of the maximum shortening velocity (Vmax) at the tetanic plateau. The estimated value of the fractional activation at 40 ms after the onset of contraction was used as a measure of the rate of activation. The rate of rise of isometric tension in different fibres was correlated with the rate of fibre activation and with Vmax during the plateau of the tetanus. Together differences in rate of activation and in Vmax accounted for 60,80% of the fibre-to-fibre variability in the rate of rise of isometric tension, depending on the measure of the force rise time used. There was not a significant correlation between the rate of fibre activation and Vmax. The steady-state F,V characteristics and the rate at which these characteristics are achieved early in contraction are seemingly independent. A simulation study based on F,V properties and series compliance in frog muscle fibres indicates that if muscle activation were instantaneous, the time taken for force to rise to 50% of the plateau value would be about 60% shorter than that actually measured from living fibres. Thus about 60% of the force rise time is a consequence of the time course of activation processes and about 40% represents time taken to stretch series compliance by activated contractile material. [source] Presupuesto de Tiempo del Chancho Cariblanco (Tayassu pecani) en un Bosque Húmedo de Costa Rica,BIOTROPICA, Issue 1 2002Mariana Altrichter ABSTRACT The diurnal time budget of four herds of white,lipped peccaries (Tayassu pecari) was studied using direct observation. The study took place from July 1996 to April 1997 in Corcovado National Park, southwestern Costa Rica. We predicted that time budget would be diagnostic of peccaries' welfare regarding food abundance. We considered that a decrease in time spent resting and in social interactions would be indicative of nutritional stress. Peccaries spent 34 percent (±1.7) of their daytime eating, 33 percent (±1.8) moving, 28 percent (±2.3) resting, 3 percent (±0.25) in social interactions, and 2.6 percent (±1.4) in other activities. The time spent resting decreased as the time spent moving and eating increased during the months of fruit scarcity. There were no differences among habitats in the proportion of time used for each activity. In the wet season, peccaries spent more time eating than in the dry season, probably because of the considerable time allocated to rooting. The monthly variation in time spent on social interactions and the frequency of agonistic interactions seemed to be related to breeding rather than fruit availability. While in the study area, peccaries traveled the longest distance in October, which coincided with the lowest fruit availability. In mid,November, the radio,marked herds left the study area and returned in January. Analyses of the peccaries' time budget suggest that fruit scarcity at die end of the wet season affected the peccaries' behavior and probably induced them to travel long distances in search of food. RESUMES Se estudió el presupuesto de tiempo diurno de cuatro manadas de chanchos cariblancos Tayassu pecari mediante observación directa desde Julio de 1996 hasta abril de 1997, en el Parque Nacional Corcovado, suroeste de Costa Rica. Se predijo que el presupuesto de tiempo puede ser usado como diagnóstico del bienestar de los chanchos en cuanto a abundancia de alimento, bajo el supuesto de que una disminución del tiempo invertido en el descanso y en las interacciones sociales seria indicativa de estres alimenticio. Los chanchos invirtieron 34 por ciento (±1.7) de su tiempo diurno en alimentación, 33 por ciento (±1.8) en desplazamiento, 28 por ciento (±2.3) en descanso, 3 por ciento (±0.2) en interacciones sociales y 2.6 por ciento (±1.4) en otras actividades. El tiempo dedicado al descanso disminuyó a medida que aumentaron las proporciones de tiempo dedicadas al desplazamiento y a la alimentación en los meses de menor disponibilidad de frutos. La proporción de tiempo usada para cada actividad no difirió signifi-cativamente entre los diferentes hábitats. En la época húmeda, los animales invirtieron más tiempo en la alimentación que en la época seca, probablemente debido a la gran proporción de tiempo que dedicaron a escarbar. La variación mensual del tiempo invertido en las interacciones sociales y la frecuencia de interacciones agonisticas se relacionaron mas con la época reproductiva que con la disponibilidad de frutos. Las distancias recorridas por los chanchos que pudieron medirse fueron mayores en octubre, coincidiendo con la menor disponibilidad de frutos. A mediados de noviembre las manadas marcadas dejaron el área de estudio y regresaron a principios de enero. El análisis del presupuesto de tiempo sugiere que la escasez de frutos al final de la época húmeda afecta el comportamiento de los chanchos y probablemente los incita a desplazarse distancias largas en busca de alimento. [source] Antimicrobial activity of varying concentrations of sodium hypochlorite on the endodontic microorganisms Actinomyces israelii, A. naeslundii, Candida albicans and Enterococcus faecalisINTERNATIONAL ENDODONTIC JOURNAL, Issue 7 2004C. E. Radcliffe Abstract Aim, To determine the resistance of microorganisms associated with refractory endodontic infections to sodium hypochlorite used as a root canal irrigant. Methodology, Two strains each of Actinomyces naeslundii, Candida albicans and Enterococcus faecalis were tested as late logarithmic phase inocula, against sodium hypochlorite adjusted to 0.5, 1.0, 2.5 and 5.25% w/v. Contact times used were 0, 10, 20, 30, 60 and 120 s. In the case of E. faecalis, additional experiments used contact times of 1.0, 2.0, 5.0, 10.0 and 30.0 min. Anti-microbial action was halted by sodium thiosulphate addition. Survivors were measured primarily using viable counts on drop plates. Additionally, pour plates were used to count low colony-forming units (cfu) and dilutions to 10,6 were used to count high cfu. Results, All concentrations of NaOCl lowered cfu below the limit of detection after 10 s in the case of A. naeslundii and C. albicans. However, E. faecalis proved to be more resistant to NaOCl. Using 0.5% NaOCl for 30 min reduced cfu to zero for both strains tested. This compares with 10 min for 1.0%, 5 min for 2.5% and 2 min for 5.25% (P < 0.001). Regression analysis for the dependent variable loge(count + 1) with loge(time + 1) and concentration as explanatory variables gave rise to a significant interaction between time and concentration (P < 0.001). Conclusion, The published association of E. faecalis with refractory endodontic infection may result, at least partially, from high resistance of this species to NaOCl. This does not appear to be the case with A. naeslundii or C. albicans. [source] Metabolite proton T2 mapping in the healthy rhesus macaque brain at 3 TMAGNETIC RESONANCE IN MEDICINE, Issue 5 2009Songtao Liu Abstract The structure and metabolism of the rhesus macaque brain, an advanced model for neurologic diseases and their treatment response, is often studied noninvasively with MRI and 1H-MR spectroscopy. Due to the shorter transverse relaxation time (T2) at the higher magnetic fields these studies favor, the echo times used in 1H-MR spectroscopy subject the metabolites to unknown T2 weighting, decreasing the accuracy of quantification which is key for inter- and intra-animal comparisons. To establish the "baseline" (healthy animal) T2 values, we mapped them for the three main metabolites' T2s at 3 T in four healthy rhesus macaques and tested the hypotheses that their mean values are similar (i) among animals; and (ii) to analogs regions in the human brain. This was done with three-dimensional multivoxel 1H-MR spectroscopy at (0.6 × 0.6 × 0.5 cm)3 = 180 ,L spatial resolution over a 4.2 × 3.0 × 2.0 = 25 cm3 (,30%) of the macaque brain in a two-point protocol that optimizes T2 precision per unit time. The estimated T2s in several gray and white matter regions are all within 10% of those reported in the human brain (mean ± standard error of the mean): N -acetylaspartate = 316 ± 7, creatine = 177 ± 3, and choline = 264 ± 9 ms, with no statistically significant gray versus white matter differences. Magn Reson Med, 2009. © 2009 Wiley-Liss, Inc. [source] | |||||||||||||||||||