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Terms modified by Decreasing Selected AbstractsEffects of dose and particle size on activated carbon treatment to sequester polychlorinated biphenyls and polycyclic aromatic hydrocarbons in marine sedimentsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 7 2005John R. Zimmerman Abstract Recent laboratory studies show that mixing activated carbon with contaminated sediment reduces the chemical and biological availability of hydrophobic organic contaminants. In this study, we test the effects of varying the activated carbon dose and particle size in reducing the aqueous availability of polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) and the uptake of PCBs by two benthic organisms. We mixed PCB- and PAH-contaminated sediment from Hunters Point Naval Shipyard, San Francisco Bay (CA, USA), for one month with activated carbon, at doses of 0.34, 1.7, and 3.4% dry mass basis. We found that increasing the carbon dose increased the effectiveness in reducing PCB bioaccumulation. In 56-d uptake tests with the benthic organisms Neanthes arenaceodentata and Leptocheirus plumulosus, PCB bioaccumulation was reduced by 93 and 90%, respectively, with 3.4% carbon. Increasing the dose also increased the effectiveness in reducing PCB and PAH aqueous concentrations and uptake by semipermeable membrane devices and quiescent flux of PCBs to overlying water. Decreasing activated carbon particle size increased treatment effectiveness in reducing PCB aqueous concentration, and larger-sized activated carbon (400,1,700 ,m) was ineffective with a contact period of one month. We invoke a numerical model based on intraparticle diffusion in sediment and activated carbon particles to help interpret our experimental results. This model was useful in explaining the trends for the effect of activated carbon dose and particle size on PCB aqueous concentrations in well-mixed systems. [source] Adalimumab sustains clinical remission and overall clinical benefit after 2 years of therapy for Crohn's diseaseALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 12 2010R. PANACCIONE Aliment Pharmacol Ther,31, 1296,1309 Summary Background, In the randomized, double-blind, placebo-controlled CHARM trial, adalimumab was more effective than placebo in maintaining clinical remission for patients with moderate-to-severe Crohn's disease (CD) through 56 weeks. Aim, To substantiate the long-term safety and clinical benefits of adalimumab through 2 years of therapy in CHARM and its open-label extension (ADHERE). Methods, Patients entering ADHERE on blinded therapy received adalimumab 40 mg every other week (eow). Patients who had already moved to open-label adalimumab eow or weekly in CHARM continued their regimens. Data were analysed by originally randomized treatment group at CHARM baseline (adalimumab 40 mg eow, adalimumab 40 mg weekly, or placebo), regardless of whether patients entered ADHERE or received open-label adalimumab (eow or weekly). Results, After up to 2 years of therapy, 37.6%, 41.9% and 49.8% of patients originally randomized to placebo, adalimumab eow and adalimumab weekly, respectively, were in clinical remission. All groups experienced sustained improvements on the Inflammatory Bowel Disease Questionnaire. Decreasing hazard rates for both all-cause and CD-related hospitalizations were observed over time. Over a 2-year period, the rates of serious adverse events and malignancies (33.3 and 1.1 events/100-patient-years respectively) were similar to those observed during the overall adalimumab CD clinical development programme. Conclusions, Adalimumab demonstrated sustained maintenance of clinical remission, improvements in quality of life and reductions in hospitalization during long-term treatment for CD, with no new safety concerns identified. [source] Performance analysis and improvement for BitTorrent-like file sharing systemsCONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 13 2007Ye Tian Abstract In this paper, we present a simple mathematical model for studying the performance of the BitTorrent (http://www.bittorrent.com) file sharing system. We are especially interested in the distribution of peers in different states of the download job progress. With the model we find that the distribution of the download peers follows an asymmetric U-shaped curve under the stable state, due to BitTorrent's unchoking strategies. In addition, we find that the seeds' departure rate and the download peers' abort rate will influence the peer distribution in different ways notably. We also analyze the content availability under the dying process of the BitTorrent file sharing system. We find that the system's stability deteriorates with decreasing and unevenly distributed online peers, and BitTorrent's built-in ,tit-for-tat' unchoking strategy could not help to preserve the integrity of the file among the download peers. We propose an innovative ,tit-for-tat' unchoking strategy which enables more peers to finish the download job and prolongs the system's lifetime. By playing our innovative strategy, download peers could cooperate to improve the stability of the system by making a trade-off between the current downloading rate and the future service availability. Finally, experimental results are presented to validate our analytical results and support our proposals. Copyright © 2007 John Wiley & Sons, Ltd. [source] The Illusory Theory of Colours: An Anti-Realist TheoryDIALECTICA, Issue 3 2006Barry Maund Despite the fact about colour, that it is one of the most obvious and conspicuous features of the world, there is a vast number of different theories about colour, theories which seem to be proliferating rather than decreasing. How is it possible that there can be so much disagreement about what colours are? Is it possible that these different theorists are not talking about the same thing? Could it be that more than one of them is right? Indeed some theorists, e.g. Leo M. Hurvich, D. L. McAdam and K. Nassau, say that the term ,colour' is used to identify a range of different properties, e.g. pigments, properties of light, and sensations. Such a view has its attractions, but it raises the question of what it is that unites these various concepts , what is it that would make them all concepts of colour? What is it that justifies using the same terms, ,yellow', ,blue', ,pink', mauve', and so on? This paper aims to address this question, arguing that its answer supports the conclusion that the best theory of colour is a form of anti-realism: the Illusory theory of colours. There are two parts to this thesis, one negative, the other positive. The negative part is that there are no colours, as they are ordinarily conceived. The positive part is that, nevertheless, the world is such that ,it is as if there are such colours'. Such a theory has important implications. One is that it doesn't fall neatly into the usual taxonomy of philosophical theories. In particular, it does not deserve the label ,eliminativist'. Another is that it allows some space for the views expressed by Hurvich, McAdam and Nassau, but not quite in the sense that they intend. [source] The interaction between armouring and particle weathering for eroding landscapesEARTH SURFACE PROCESSES AND LANDFORMS, Issue 10 2006Saniya Sharmeen Abstract The interaction between particle weathering and surface armouring and its effect on erosion has been investigated. The effect of soil armouring is to decrease sediment transport with time by preferentially stripping away fine particles. On the other hand the effect of weathering, which breaks down the particles in the armour, is generally believed to increase erosion. By extending an existing armouring model, ARMOUR, and using a variety of published weathering mechanisms this interaction has been explored. The model predicts that while this is generally true, in some cases erosion can be decreased by weathering. When the particles generated by weathering were approximately of equal diameter, erosion increased while armouring decreased. When weathering produced very fine particles by spalling, erosion increased and armouring also increased. When weathering produced a range of particles from fine to coarse, the armour layer broke down and erosion decreased relative to the no-weathering case. This latter decrease in erosion was due to the high entrainment of coarser transportable materials from the bed decreasing the sediment transport capacity of the flow. In these studies clear regimes could be identified where erosion was limited by either the energy of the flow alone (i.e. ,transport-limited'), or the rate of weathering (,weathering-limited'); however, for some mechanisms there was an interaction between the two, which we called ,weathering/transport limited'. Copyright © 2006 John Wiley & Sons, Ltd. [source] Effect of alkali metal hydroxides on the enantioseparation of amines using di- O -isopropylidene-keto- L -gulonic acid as the selector in NACEELECTROPHORESIS, Issue 22 2006Ylva Hedeland Dr. Abstract The present work demonstrates the importance of the ionic composition in the BGE for enantioseparation. (,)-2,3:4,6-di- O -Isopropylidene-2-keto- L -gulonic acid ((,)-DIKGA) has been used as the chiral selector in methanolic and ethanolic BGEs. The influence of added alkali metal hydroxides on the EOF and the chiral separation of amines (atenolol, isoprenaline, pindolol and propranolol) have been studied. The ion-pair formation constants in ethanol were determined by precision conductometry for the enantiomers of pindolol with (,)-DIKGA, for Li+, Na+ and Cs+ with (,)-DIKGA, and also for the corresponding alkali metal hydroxides. The effective mobilities and the enantiomeric mobility differences were affected by the type of alkali metal hydroxide (LiOH, NaOH, KOH, RbOH or CsOH) added to the BGE. The effective mobility and mobility difference were increased with decrease in solvated radius of the alkali metal cation. These differences could partly be correlated to the ion-pair formation constants of the alkali metal cations with the chiral selector, affecting the equilibrium concentration of the free selector. The electroosmosis was also affected by the alkali metal hydroxide added to the BGE. The cathodic electroosmosis decreased with decreasing solvated radius of the alkali metal cation added to the BGE. Interestingly, the cathodic EOF was even reversed, i.e. became anodic in the ethanolic BGEs containing KOH, RbOH or CsOH and the methanolic ones with RbOH and CsOH. [source] Evaluation of the role of black carbon in attenuating bioaccumulation of polycyclic aromatic hydrocarbons from field-contaminated sediments,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 11 2004Brita Sundelin Abstract The significance of black carbon (BC) for the bioavailability of polycyclic aromatic hydrocarbons (PAHs) was examined by using historically contaminated intact sediment cores in laboratory exposure experiments with the deposit-feeding amphipod Monoporeia affinis. Log values of amphipod biota,sediment accumulation factors (BSAFs) were significantly related to log BC, whereas log BSAFs were related to log octanol,water partition coefficients only in background sediments containing less BC. In the background sediments, the BSAF for polycyclic aromatic hydrocarbons (PAHs) was 1 to 2 for phenanthrene, with lower values for more hydrophobic PAHs, indicating an increase in nonequilibrium conditions with increasing PAH molecular size. For the near-equilibrated phenanthrene and fluoranthene, higher BSAFs were measured during exposure to background sediments, with BSAF decreasing to <0.1 in contaminated sediments in the Stockholm waterways. In situ caged mussels (Dreissena polymorpha) exhibited field BSAF values (relative to sediment-trap,collected suspended matter) for polychlorinated biphenyls (PCBs) of 0.1 to 0.4, but for PAHs of similar hydrophobicity and molecular size, the field BSAFs were much lower and in the range 0.002 to 0.05. This PAH,PCB dichotomy is consistent with recently reported much stronger binding to diesel soot (a form of BC) for PAHs than for PCBs of equal hydrophobicities. Lower BSAFs for the near-equilibrated PAHs (phenanthrene and fluoranthene) in the urban sediments relative to the background sediments were consistent with the larger presence of BC in the urban sediments. This study provides the first linked BSAF,BC field data that supports a causal relationship between strong soot sorption and reduced bioavailability for PAHs. [source] Evaluation of reduced rank semiparametric models to assess excess of risk in cluster analysisENVIRONMETRICS, Issue 4 2009Marco Geraci Abstract The existence of multiple environmental hazards is obviously a threat to human health and, from a statistical point of view, the modeling and the detection of disease clusters potentially related to those hazards offer challenging tasks. In this paper, we consider low rank thin plate spline (TPS) models within a semiparametric approach to focused clustering for small area health data. Both the distance from a putative source and a general, unspecified clustering process are modeled in the same fashion and they are entered log-additively in mixed Poisson-Normal models. Some issues related to the identification of the random effects arising from this approach are investigated. Under different simulated scenarios, we evaluate the proposed models using conditional Akaike's weights and tests for variance components, providing a comprehensive model selection methodology easy to implement. We examine observations of lung cancer deaths taken in Ohio between 1987 and 1988. These data were analyzed on several occasions to investigate the risk associated with a putative source in Hamilton county. In our analysis, we found a strong south-eastward spatial trend which is confounded with a significant radial distance effect decreasing between 0 and 150 km from the point source. Copyright © 2008 John Wiley & Sons, Ltd. [source] Inflammatory airway disease, nasal discharge and respiratory infections in young British racehorsesEQUINE VETERINARY JOURNAL, Issue 3 2005J. L. N. WOOD Summary Reasons for performing study: Respiratory disease is important in young Thoroughbred racehorses, but the variation in the rates of occurrence between different ages and training groups has not been characterised. Objectives: To determine the rates of respiratory disease, particularly inflammatory airway disease (IAD), as well as evidence of infection, and their variation between age and group. Methods: Horses were examined monthly in 7 British flat training yards over a 3 year period. IAD was defined as increased mucus in the trachea with increased proportions of neutrophils in tracheal wash samples. Frequencies of disease outcomes were estimated from the data. Results: The prevalence of IAD was 13.8% and the incidence was 8.9 cases/100 horses/month. Rates varied with training and age groups, decreasing in older animals. The prevalence of nasal discharge (ND) was 4.1%. Rates of bacterial isolation were more common than viral infections. The incidence and prevalence of several bacterial species decreased with age. Conclusions: IAD and ND were common in young racehorses, varying significantly between training groups and decreasing with age, consistent with infection playing a role in aetiology. Potential relevance: The high prevalence of IAD in 2-year-old horses in Britain suggests that routine endoscopic examination may be helpful in providing early diagnosis and appropriate therapy. The transmission of bacteria and viruses within and between groups of young animals and the role of infection, stable environment and factors inherent to each horse, including their genetic make-up, in the multifactorial aetiology of the disease all merit further study. [source] REVIEW: Self-administration of cocaine, cannabis and heroin in the human laboratory: benefits and pitfallsADDICTION BIOLOGY, Issue 1 2009Margaret Haney ABSTRACT The objective of this review is to describe self-administration procedures for modeling addiction to cocaine, cannabis and heroin in the human laboratory, the benefits and pitfalls of the approach, and the methodological issues unique to each drug. In addition, the predictive validity of the model for testing treatment medications will be addressed. The results show that all three drugs of abuse are reliably and robustly self-administered by non-treatment-seeking research volunteers. In terms of pharmacotherapies, cocaine use is extraordinarily difficult to disrupt either in the laboratory or in the clinic. A range of medications has been shown to significantly decrease cocaine's subjective effects and craving without decreasing either cocaine self-administration or cocaine abuse by patients. These negative data combined with recent positive findings with modafinil suggest that self-administration procedures are an important intermediary step between pre-clinical and clinical studies. In terms of cannabis, a recent study suggests that medications that improve sleep and mood during cannabis withdrawal decrease the resumption of marijuana self-administration in abstinent volunteers. Clinical data on patients seeking treatment for their marijuana use are needed to validate these laboratory findings. Finally, in contrast to cannabis or cocaine dependence, there are three efficacious Food and Drug Administration-approved medications to treat opioid dependence, all of which decrease both heroin self-administration and subjective effects in the human laboratory. In summary, self-administration procedures provide meaningful behavioral data in a small number of individuals. These studies contribute to our understanding of the variables maintaining cocaine, marijuana and heroin intake, and are important in guiding the development of more effective drug treatment programs. [source] Mortality from multiple sclerosis in Austria 1970,2001: dynamics, trends, and prospectsEUROPEAN JOURNAL OF NEUROLOGY, Issue 8 2004E. Ekestern A divergence in earlier multiple sclerosis (MS) mortality rates observed within Europe, prompted us to determine the MS mortality rate in Austria and several European countries. Our aim was to examine the temporal and geographical variations within Austria and to determine future MS mortality rates based on a projection model. MS mortality data set, differentiated by age groups, sex, and region at death for the period 1970,2001 were obtained. Prognostic MS mortality trends for the period 2002,2020 were estimated using the simultaneous multiple cause,delay (SIMCAD) method. Our findings indicate a decline (47%) in the MS mortality rate from 1.41 (1970,79) to 0.96 (1980,89) and 0.70 (1990,2001) per 100 000 in Austria during the 32-year period observed. Conversely, the scenarios of our projection for the period 2002,2020, reveal an increasing MS mortality rate. The median age at death because of MS increased with 0.7 years for men and 2.9 years for women during the observed period (1970,2001). Austria, like many other European countries, has experienced a decreasing MS mortality rate over the last three decades. An increased MS mortality rate is however expected over the next decades in Austria. This increase will be most prominent in the elderly population cohorts because of demographic shifts. [source] Saturation and self-inhibition of rat hippocampal GABAA receptors at high GABA concentrationsEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 12 2002Katarzyna Mercik Abstract Current responses to ultrafast ,-aminobutyric acid (GABA) applications were recorded from excised patches in rat hippocampal neurons to study the gating properties of GABAA receptors at GABA concentrations close to saturating ones and higher. The amplitude of currents saturated at approximately 1 mm, while the onset rate of responses reached saturation at 4,6 mm GABA. At high GABA concentrations (> 10 mm), the amplitude of current responses was reduced in a dose-dependent manner with a half-blocking GABA concentration of approximately 50 mm. The peak reduction at high GABA doses was accompanied by a tendency to increase the steady-state to peak ratio. At concentrations higher than 30 mm, this effect took the form of a rebound current, i.e. during the prolonged GABA applications, the current firstly declined due to desensitization onset and then, instead of decreasing towards a steady-state value, clearly increased. Both the self-inhibition of GABAA receptors by high GABA doses and rebound were clearly voltage dependent, being larger at positive holding potentials. The fast desensitization component accelerated with depolarization at all saturating [GABA] tested. The rebound phenomenon indicates that the self-block of GABAA receptors is state dependent, and suggests that the sojourn in the desensitized conformation provides a ,rescue' from the block. We propose that high GABA concentrations inhibit the receptors by direct occlusion of the channel pore having no effect on the receptor gating. [source] Experimental study on water spray suppression on burning upholstered chair in an enclosure with different application timesFIRE AND MATERIALS, Issue 5 2009Q. Y. Xie Abstract The objective of this work is to investigate the effects of the application time of water spray on the burning upholstered chair in an enclosure. A series of experiments are conducted with the same water flow rate in an ISO 9705 fire test room in which a water spray system is installed. Several identical upholstered chairs are used in the experiments with the application times 20, 25, 30, 40 and 45,s after the ignition of upholstered chair, respectively. The results show that there is nearly an exponential relationship between the peak heat release rates and the relative application times of water spray. It is also shown that there is a polynomial relationship between the relative time for the peak heat release rate and the relative application time of water spray. However, there is an exponential relationship between the whole relative extinguishing time and the relative application time of water spray. A sudden increase is detected before the decreasing of CO generation rates after the water spray is applied on the burning upholstered chair. The average temperatures of the upper hot smoke layer under the ceiling will generally be lower with the earlier application of water spray. Copyright © 2009 John Wiley & Sons, Ltd. [source] Genetic and environmental influences on Anxious/Depression during childhood: a study from the Netherlands Twin RegisterGENES, BRAIN AND BEHAVIOR, Issue 8 2005D. I. Boomsma For a large sample of twin pairs from the Netherlands Twins Register who were recruited at birth and followed through childhood, we obtained parental ratings of Anxious/Depression (A/D). Maternal ratings were obtained at ages 3 years (for 9025 twin pairs), 5 years (9222 pairs), 7 years (7331 pairs), 10 years (4430 pairs) and 12 years (2363 pairs). For 60,90% of the pairs, father ratings were also available. Multivariate genetic models were used to test for rater-independent and rater-specific assessments of A/D and to determine the genetic and environmental influences on individual differences in A/D at different ages. At all ages, monozygotic twins resembled each other more closely for A/D than dizygotic twins, implying genetic influences on variation in A/D. Opposite sex twin pairs resembled each other to same extent as same-sex dizygotic twins, suggesting that the same genes are expressed in boys and girls. Heritability estimates for rater-independent A/D were high in 3-year olds (76%) and decreased in size as children grew up [60% at age 5, 67% at age 7, 53% at age 10 (60% in boys) and 48% at age 12 years]. The decrease in genetic influences was accompanied by an increase in the influence of the shared family environment [absent at ages 3 and 7, 16% at age 5, 20% at age 10 (5% in boys) and 18% at age 12 years]. The agreement between parental A/D ratings was between 0.5 and 0.7, with somewhat higher correlations for the youngest group. Disagreement in ratings between the parents was not merely the result of unreliability or rater bias. Both the parents provided unique information from their own perspective on the behavior of their children. Significant influences of genetic and shared environmental factors were found for the unique parental views. At all ages, the contribution of shared environmental factors to variation in rater-specific views was higher for father ratings. Also, at all ages except age 12, the heritability estimates for the rater-specific phenotype were higher for mother ratings (59% at age 3 and decreasing to 27% at age 12 years) than for father ratings (between 14 and 29%). Differences between children, even as young as 3 years, in A/D are to a large extent due to genetic differences. As children grow up, the variation in A/D is due in equal parts to genetic and environmental influences. Anxious/Depression, unlike many other common childhood psychopathologies, is influenced by the shared family environment. These findings may provide support for why certain family therapeutic approaches are effective in the A/D spectrum of illnesses. [source] Global analysis of reptile elevational diversityGLOBAL ECOLOGY, Issue 4 2010Christy M. McCain ABSTRACT Aim, Latitudinal- and regional-scale studies of reptile diversity suggest a predominant temperature effect, unlike many other vertebrate richness patterns which tend to be highly correlated with both temperature and water variables. Here I examine montane gradients in reptile species richness with separate analyses of snakes and lizards from mountains around the world to assess a predominant temperature effect and three additional theories of diversity, including a temperature,water effect, the species,area effect and the mid-domain effect (MDE). Location, Twenty-five elevational gradients of reptile diversity from temperate, tropical and desert mountains in both hemispheres, spanning 10.3° N to 46.1° N. Methods, Elevational gradients in reptile diversity are based on data from the literature. Of the 63 data sets found or compiled, only those with a high, unbiased sampling effort were used in analyses. Twelve predictions and three interactions of diversity theory were tested using nonparametric statistics, linear regressions and multiple regression with the Akaike information criterion (AIC). Results, Reptile richness and, individually, snake and lizard richness on mountains followed four distinct patterns: decreasing, low-elevation plateaus, low-elevation plateaus with mid-elevation peaks, and mid-elevation peaks. Elevational reptile richness was most strongly correlated with temperature. The temperature effect was mediated by precipitation; reptile richness was more strongly tied to temperature on wet gradients than on arid gradients. Area was a secondary factor of importance, whereas the MDE was not strongly associated with reptile diversity on mountains. Main conclusions, Reptile diversity patterns on mountains did not follow the predicted temperature,water effect, as all diversity patterns were found on both wet and dry mountains. But the influence of precipitation on the temperature effect most likely reflects reptiles' use of radiant heat sources (sunning opportunities) that are more widespread on arid mountains than wet mountains due to lower humidity, sparser vegetation and less cloud cover across low and intermediate elevations. [source] Detection of trends in hydrological extremes for Canadian watershedsHYDROLOGICAL PROCESSES, Issue 13 2010Donald H. Burn Abstract The potential impacts of climate change can alter the risk to critical infrastructure resulting from changes to the frequency and magnitude of extreme events. As well, the natural environment is affected by the hydrologic regime, and changes in high flows or low flows can have negative impacts on ecosystems. This article examines the detection of trends in extreme hydrological events, both high and low flow events, for streamflow gauging stations in Canada. The trend analysis involves the application of the Mann,Kendall non-parametric test. A bootstrap resampling process has been used to determine the field significance of the trend results. A total of 68 gauging stations having a nominal record length of at least 50 years are analysed for two analysis periods of 50 and 40 years. The database of Canadian rivers investigated represents a diversity of hydrological conditions encompassing different extreme flow generating processes and reflects a national scale analysis of trends. The results reveal more trends than would be expected to occur by chance for most of the measures of extreme flow characteristics. Annual and spring maximum flows show decreasing trends in flow magnitude and decreasing trends in event timing (earlier events). Low flow magnitudes exhibit both decreasing and increasing trends. Copyright © 2010 John Wiley & Sons, Ltd. [source] Using a pore-scale model to quantify the effect of particle re-arrangement on pore structure and hydraulic propertiesHYDROLOGICAL PROCESSES, Issue 8 2007Oagile Dikinya Abstract A pore-scale model based on measured particle size distributions has been used to quantify the changes in pore space geometry of packed soil columns resulting from a dilution in electrolyte concentration from 500 to 1 mmol l,1 NaCl during leaching. This was applied to examine the effects of particle release and re-deposition on pore structure and hydraulic properties. Two different soils, an agricultural soil and a mining residue, were investigated with respect to the change in hydraulic properties. The mining residue was much more affected by this process with the water saturated hydraulic conductivity decreasing to 0·4% of the initial value and the air-entry value changing from 20 to 50 cm. For agricultural soil, there was little detectable shift in the water retention curve but the saturated hydraulic conductivity decreased to 8·5% of the initial value. This was attributed to localized pore clogging (similar to a surface seal) affecting hydraulic conductivity, but not the microscopically measured pore-size distribution or water retention. We modelled the soil structure at the pore scale to explain the different responses of the two soils to the experimental conditions. The size of the pores was determined as a function of deposited clay particles. The modal pore size of the agricultural soil as indicated by the constant water retention curve was 45 µm and was not affected by the leaching process. In the case of the mining residue, the mode changed from 75 to 45 µm. This reduction of pore size corresponds to an increase of capillary forces that is related to the measured shift of the water retention curve. Copyright © 2007 John Wiley & Sons, Ltd. [source] CREDIT CONSTRAINTS IN THE MARKET FOR CONSUMER DURABLES: EVIDENCE FROM MICRO DATA ON CAR LOANS,INTERNATIONAL ECONOMIC REVIEW, Issue 2 2008Orazio P. Attanasio We investigate the significance of borrowing constraints in the market for consumer loans. Using data from the Consumer Expenditure Survey on auto loan contracts we estimate the elasticities of loan demand with respect to interest rate and maturity. We find that, with the exception of high income households, consumers are very responsive to maturity and less responsive to interest rate changes. Both elasticities vary with household income, with the maturity elasticity decreasing and the interest rate elasticity increasing with income. We argue that these results are consistent with the presence of binding credit constraints in the auto loan market. [source] Theory and finite element computation of cyclic martensitic phase transformation at finite strainINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 1 2008Erwin Stein Abstract A generalized variational formulation, including quasi-convexification of energy wells for arbitrarily many martensitic variants in case of mono-crystals for linearized strains, was developed by Govindjee and Miehe (Comp. Meth. Appl. Mech. Eng. 2001; 191(3,5):215,238) and computationally extended by Stein and Zwickert (Comput. Mech. 2006; in press). This work is generalized here for finite strain kinematics with monotonous hyperelastic stress,strain functions in order to account for large transformation strains that can reach up to 15%. A major theoretical and numerical difficulty herein is the convexification of the finite deformation phase transformation (PT) problems for multiple phase variants, n,2. A lower bound of the mixing energy is provided by the Reuss bound in case of linear kinematics and an arbitrary number of variants, shown by Govindjee et al. (J. Mech. Phys. Solids 2003; 51(4):I,XXVI). In case of finite strains, a generalized representation of free energy of mixing is introduced for a quasi-Reuss bound, which in general holds for n,2. Numerical validation of the used micro,macro material model is presented by comparing verified numerical results with the experimental data for Cu82Al14Ni4 monocrystals for quasiplastic PT, provided by Xiangyang et al. (J. Mech. Phys. Solids 2000; 48:2163,2182). The zigzag-type experimental stress,strain curve within PT at loading, called ,yield tooth', is approximated within the finite element analysis by a smoothly decreasing and then increasing axial stress which could not be achieved with linearized kinematics yielding a constant axial stress during PT. Copyright © 2007 John Wiley & Sons, Ltd. [source] Structural changes and shrinkage of potato during fryingINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 1 2001Rui M. Costa Summary Light microscopy was used to study changes in cell size, blister formation and crust evolution during potato frying. Frying experiments with both French fries and crisps of different thickness (1,5 mm) were performed at temperatures of 140 and 180 °C. Thickness, volume and density changes were also measured. The formation of crust in French fries starts after the potato surface reached approximately 103 °C, and then the crust thickness increased linearly with the square root of frying time, this increase being faster at 180 °C. The potato volume decreased during frying, although in the late stages the volume may increase because of oil uptake and cell separation caused by entrapped water vapour. Shrinkage was adequately described by the Weibull model with a residual value, with shrinkage rate increasing with temperature and decreasing with potato thickness. The residual volume was not affected by temperature (65% for French fries and 59,30 for crisps, depending on thickness). Volume appeared to decrease mainly as the result of water loss, except for very low water content, and thus potato density changes were very small. [source] Age-related change in breeding performance in early life is associated with an increase in competence in the migratory barn swallow Hirundo rusticaJOURNAL OF ANIMAL ECOLOGY, Issue 5 2007JAVIER BALBONTÍN Summary 1We investigated age-related changes in two reproductive traits (laying date and annual fecundity) in barn swallows Hirundo rustica L. using a mixed model approach to di-stinguish among between- and within-individual changes in breeding performance with age. 2We tested predictions of age-related improvements of competence (i.e. constraint hypothesis) and age-related progressive disappearance of poor-quality breeders (i.e. selection hypothesis) to explain age-related increase in breeding performance in early life. 3Reproductive success increased in early life, reaching a plateau at middle age (e.g. at 3 years of age) and decreasing at older age (> 4 years). Age-related changes in breeding success were due mainly to an effect of female age. 4Age of both female and male affected timing of reproduction. Final linear mixed effect models (LME) for laying date included main and quadratic terms for female and male age, suggesting a deterioration in reproductive performance at older age for both males and females. 5We found evidence supporting the constraints hypothesis that increases in competence within individuals, with ageing being the most probable cause of the observed increase in breeding performance with age in early life. Two mechanisms were implicated: (1) advance in male arrival date with age provided middle-aged males with better access to mates. Yearling males arrived later to the breeding grounds and therefore had limited access to high-quality mates. (2) Breeding pairs maintaining bonds for 2 consecutive years (experienced pairs) had higher fecundity than newly formed inexperienced breeding pairs. 6There was no support for the selection hypothesis because breeding performance was not correlated with life span. 7We found a within-individual deterioration in breeding and migratory performance (arrival date) in the oldest age-classes consistent with senescence in these reproductive and migratory traits. [source] Habitat heterogeneity affects population growth in goshawk Accipiter gentilisJOURNAL OF ANIMAL ECOLOGY, Issue 2 2001Oliver Krüger Summary 1The concept of site-dependent population regulation combines the ideas of Ideal Free Distribution-type of habitat settlement and density dependence in a vital rate mediated by habitat heterogeneity. The latter is also known as habitat heterogeneity hypothesis. Site-dependent population regulation hypothesis predicts that increasing population density should lead to inhabitation of increasingly poor territories and decreasing per capita population growth rate. An alternative mechanism for population regulation in a territorial breeding system is interference competition. However, this would be expected to cause a more even decrease in individual success with increasing density than site-dependent regulation. 2We tested these ideas using long-term (1975,99) population data from a goshawk Accipiter gentilis population in Eastern Westphalia, Germany. 3Goshawk territory occupancy patterns and reproduction parameters support predictions of site-dependent population regulation: territories that were occupied more often and earlier had a higher mean brood size. Fecundity did not decrease with increasing density in best territories. 4Using time-series modelling, we also showed that the most parsimonious model explaining per capita population growth rate included annual mean habitat quality, weather during the chick rearing and autumn period and density as variables. This model explained 63% of the variation in per capita growth rate. The need for including habitat quality in the time-series model provides further support for the idea of site-dependent population regulation in goshawk. [source] Effect of dietary ,-tocopherol + ascorbic acid, selenium, and iron on oxidative stress in sub-yearling Chinook salmon (Oncorhynchus tshawytscha Walbaum)JOURNAL OF ANIMAL PHYSIOLOGY AND NUTRITION, Issue 1 2009T. L. Welker Summary A three-variable central composite design coupled with surface-response analysis was used to examine the effects of dietary ,-tocopherol + ascorbic acid (TOCAA), selenium (Se), and iron (Fe) on indices of oxidative stress in juvenile spring Chinook salmon. Each dietary factor was tested at five levels for a total of fifteen dietary combinations (diets). Oxidative damage in liver and kidney (lipid peroxidation, protein carbonyls) and erythrocytes (erythrocyte resistance to peroxidative lysis, ERPL) was determined after feeding experimental diets for 16 (early December) and 28 (early March) weeks. Only TOCAA influenced oxidative stress in this study, with most measures of oxidative damage decreasing (liver lipid peroxidation in December and March; ERPL in December; liver protein carbonyl in March) with increasing levels of TOCAA. We also observed a TOCAA-stimulated increase in susceptibility of erythrocytes to peroxidative lysis in March at the highest levels of TOCAA. The data suggest that under most circumstances a progressive decrease in oxidative stress occurs as dietary TOCAA increases, but higher TOCAA concentrations can stimulate oxidative damage in some situations. Higher levels of TOCAA in the diet were required in March than in December to achieve comparable levels of protection against oxidative damage, which may have been due to physiological changes associated with the parr-smolt transformation. Erythrocytes appeared to be more sensitive to variation in dietary levels of TOCAA than liver and kidney tissues. Using the March ERPL assay results as a baseline, a TOCAA level of approximately 350,600 mg/kg diet would provide adequate protection against lipid peroxidation under most circumstances in juvenile Chinook salmon. [source] Application of small-angle scattering to study the effects of moisture content on a native soy proteinJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 3 2008Catherine S. Kealley The nano- and microstructure of glycinin, a soybean protein, has been investigated as a function of moisture for moisture contents between 4 and 21,wt%. Glycinin exhibits peaks in the small-angle region whose positions show minimal change with X-rays for samples up to 13% moisture. However, the use of neutron scattering, and the associated enhancement in contrast, results in the Bragg peaks being well resolved up to higher moisture contents; the associated shift in peak positions between 4 and 21% moisture are consistent with the expansion of a hexagonal unit cell as a function of moisture content. A Porod slope of ,,4 indicates that the interface between the `dry' protein powder and the surrounding medium at a length-scale of at least 3,µm down to ,20,nm is smooth and sharp. Scanning electron microscopy indicates that the powders, with low moisture content, have a porous appearance, with the porosity decreasing and microstructure expanding as the moisture content increases. [source] Predicting plant species' responses to grazingJOURNAL OF APPLIED ECOLOGY, Issue 5 2001Peter A. Vesk Summary 1The aim of this study was to identify whether plant species show consistent responses to livestock grazing. The analyses were based on 35 published studies from Australian rangelands providing 55 species response lists. The primary data set comprised 1554 responses from 829 species. 2Eight-hundred and twenty-nine species were categorized as increasers, decreasers or neutral under grazing. Of 324 species that occurred in at least two response lists, 133 (41%) responded inconsistently, increasing at least once and decreasing at least once. While 59% of species responded consistently, these results suggest that our ability to predict vegetation change under grazing is limited. 3Particular species were not inherently more or less consistent. Rather, as species occurred in more trials, the likelihood of at least one opposite response increased; no species that occurred at least eight times was wholly consistent. A binomial model indicated that the probability of an opposite response, across all species, was 0·275. 4Contrary responses within species must result from context rather than from species' traits. Species were more likely to decrease in response to grazing at lower rainfall than at higher rainfall. Forbs tended to increase under grazing at sites where wet seasons were cooler. Changing the grazing animal was weakly correlated with change in response direction, although not enough for it to be useful for manipulating pasture composition. We found little support for ideas that different responses within species are due to differences in alternative forage available, or due to non-linearity of response to grazing intensity. 5At present it appears we can predict species response direction about three-quarters of the time, at a continental scale. This represents an upper limit of the reliability of prediction based on species' traits alone. Presently we do not know what aspects of the context might allow us to predict reliably the remaining one-quarter of responses. [source] Dietary vitamin A requirement of juvenile Amur sturgeon (Acipenser schrenckii)JOURNAL OF APPLIED ICHTHYOLOGY, Issue 5 2008H. Wen Summary The present experiment was conducted to determine the dietary vitamin A requirement of juvenile Amur sturgeon (Acipenser schrenckii) by formulating seven semipurified diets containing 10, 258, 510, 1050, 2020, 4100 and 8300 IU vitamin A (as retinol acetate) kg,1 diet, respectively. Each experimental diet was fed to triplicate groups of 20 juveniles each with initial average weights of 12.09 ± 0.22 g in 405-L aquaria and maintained at 25.0 ± 2.0°C for 8 weeks. Fish fed the basal diet (10 IU vitamin A kg,1 diet) exhibited poor appetite and activity, whereas these signs were not observed in any group fed vitamin A-supplemented diets. Weight gain, feed efficiency and hepatosomatic index increased significantly with increases in the dietary vitamin A level, reaching a peak with the vitamin A 1050 IU kg,1 diet, and then decreasing. Muscle chemical compositions were not affected by the dietary vitamin A levels. Vitamin A concentrations in liver and muscle increased significantly as the vitamin A levels increased within a range of 10,4100 IU kg,1 diet; above this level there were no significant changes. Broken-line regression analysis of weight gain and liver vitamin A concentration against the dietary vitamin A level showed that juvenile Amur sturgeon required a minimum of 923 IU vitamin A kg,1 in the diet for maximal growth, and 1981 IU kg,1 for highest liver vitamin A accumulation. [source] Dynamics of black spot sea bream (Pagellus bogaraveo) mean length: evaluating the influence of life history parameters, recruitment, size selectivity and exploitation ratesJOURNAL OF APPLIED ICHTHYOLOGY, Issue 3 2006K. Erzini Summary Stochastic simulations were used to evaluate the influence of recruitment pattern (log-normal, decreasing), size selectivity (normal, logistic model) and fishing mortality pattern (abrupt, continuous increase in fishing mortality) on the evolution of mean length and the dispersion of mean length for a relatively long-lived deep-water species, the black spot sea bream (Pagellus bogaraveo). An abrupt increase in fishing mortality resulted in mean size decreasing and stabilizing at a lower level while a steady increase in fishing mortality caused the continuous decrease in mean size that has been reported for many long-lived species. Decrease in mean size was greatest for logistic model simulations and for cases where fish were susceptible to capture at a small size. Logistic selectivity, with decreasing recruitment and increasing fishing mortality over time, resulted in mean length and variability in mean length trends similar to that observed for the Strait of Gibraltar fishery. Furthermore, it was found with the declining recruitment that moderate increases in fishing mortality can result in significant decreases in mean length. Given the importance of mean size as an indicator of the state of a resource, these simulations are a useful alternative or complement to standard fisheries assessment methods, helping to provide information on exploitation patterns and rates that can be used for conservation and management. [source] Spatial and ontogenetic variability in the microhabitat use of stream-dwelling spined loach (Cobitis taenia) and stone loach (Barbatula barbatula)JOURNAL OF APPLIED ICHTHYOLOGY, Issue 6 2004G. H. Copp Summary Ontogenetic and spatial variability in microhabitat use of spined loach Cobitis taenia (Linnaeus), considered as one species for the purposes of this study, and stone loach Barbatula barbatula (Linnaeus) were examined in the River Great Ouse basin, England, using multivariate and habitat suitability methods, including a technique for handling spatial variation in collections of preference curves. Distinct ordinations of spined age classes and stone loach developmental stages, respectively, in canonical correspondence analysis of species × variables × samples relationships suggest that the two species occupy completely different microhabitats; however, young-of-the-year spined loach occurred more often than expected with all developmental stages of stone loach except young larvae. Water velocity and filamentous algae were the most influential microhabitat variables, the latter decreasing in importance with increasing age of both fish species. Preferred water velocities generally decreased with age in spined loach and increased in stone loach, with substratum size generally increasing with fish age in both species. Spatial variation in microhabitat preferences was great in both species but less so in the spined loach, suggesting that limited plasticity in habitat use could account, at least in part, for the latter species' limited distribution and abundance in the catchment. Preference curves for a species, if generated and verified for all life intervals and all seasons, could be used as a management tool for a given stream or sector of river basin. But preference curves should be generated for each location to ensure that river management decisions with regard habitat and species conservation consider local-level species requirements. Thus, a multi-(eco)species and multi-scale approach is required in habitat suitability assessments. [source] Use of a systematic review to assist the development of Campylobacter control strategies in broilersJOURNAL OF APPLIED MICROBIOLOGY, Issue 2 2006A. Adkin Abstract Aims:, Produce an evidence-based ranking of the major contributing factors and sources of Campylobacter occurrence in broilers produced in England, Scotland and Wales , Great Britain (GB). Method and Results:, Relevant data were extracted from 159 research papers and findings were grouped into 14 sources of on-farm contamination and 37 contributing factors. A relevancy score was developed to take into account various measures from each study of applicability to GB broilers and strength of findings. Results indicate that major sources of Campylobacter include a depopulation event, another house on-farm, on-farm staff, and other animals on farm. The depopulation schedule (staggered slaughter) and multiple houses on-farm were identified as contributing factors associated with increasing the risk, and those decreasing the risk were use of a hygiene barrier, parent company and certain seasons of rearing. Conclusions:, Although the review was more resource intensive compared to narrative studies, the system allows an increased level of transparency and the ability to investigate patterns and trends. Significance and Impact of the Study:, This paper provides the first evidence-based ranking of the major sources and contributing factors for Campylobacter presence in broilers in GB using a systematic review. [source] Study on bulk polymerization of methyl methacrylate initiated by low intensity ultrasonic irradiationJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010Sude Ma Abstract Methyl methacrylate (MMA) was polymerized in bulk solutions using low intensity ultrasonic radiation of 0.25 W/cm2. The polymerization occurred after 1 h of irradiation time was applied. The polymerization rate was greatly accelerated either by increasing the amount of poly (methyl methacrylate) (PMMA) granular added into the system or by elongating the irradiation time. However, it was found that the reaction rate increased with the decreasing of the ultrasonic frequencies when the exposure time of the polymerization under the irradiation was less than 3 h. Experimental results verified that the polymerization was initiated by free radicals, which were mainly generated from the degradation of PMMA macromolecular chains, the friction between the polymer macromolecular chains and the solvent monomer. These findings were obviously different from those obtained when high intensity ultrasonic irradiation was used. The polymers fabricated in this study by using ultrasound irradiation have a narrower molecular weight distribution compared to those obtained from the polymerizations induced by the conventional initiators. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] | |||||||||||||||||||||||||||||||||||||||||||||||||||||||