bluuebunny/crossref_metadata_2025_split huggingface dataset:
Leaf Decomposition in a Dry Season Irrigation Experiment in Eastern Amazonian Forest Regrowth
Authors: Vasconcelos Steel Silva , Zarin Daniel Jacob , Da Rosa Maria Beatriz Silva , De Assis Oliveira Francisco , De Carvalho Cláudio José Reis 
Published: May 2007

ABSTRACTLeaf‐litter decomposition is a major component of carbon and nutrient dynamics in tropical forest ecosystems, and moisture availability is widely considered to be a major influence on decomposition rates. Here, we report the results of a study of leaf‐litter decomposition of five tree species in response to dry‐season irrigation in a tropical forest regrowth stand in the Brazilian Amazon; three experiments differing in the timing of installation and duration allowed for an improved resolution of irrigation effects on decomposition. We hypothesized that decomposition rates would be faster under higher moisture availability in the wet season and during dry‐season irrigation periods in the treatment plots, and that decomposition rates would be faster for species with higher quality leaves, independent of treatment. The rates of decomposition (k) were up to 2.4 times higher in irrigated plots than in control plots. The highestkvalues were shown byAnnona paludosa(0.97 to 1.26/yr) whileOcotea guianensis(0.73 to 0.85/yr) had the lowest values; intermediate rates were found forLacistema pubescens(0.91 to 1.02/yr) andVismia guianensis(0.91 to 1.08/yr). These four tree species differed significantly in leaf‐litter quality parameters (nitrogen, phosphorus, lignin, and cellulose concentrations, as well as lignin:nitrogen and carbon:nitrogen ratios), but differences in decomposition rates among tree species were not strictly correlated with leaf‐litter quality. Overall, our results show that dry‐season moisture deficits limit decomposition in Amazonian forest regrowth.
Distinguishing Sources of Ground Water Recharge by Using δ2H and δ18O
Authors: Blasch Kyle W. , Bryson Jeannie R. 
Published: May 2007

AbstractStable isotope values of hydrogen and oxygen from precipitation and ground water samples were compared by using a volumetrically based mixing equation and stable isotope gradient to estimate the season and location of recharge in four basins. Stable isotopes were sampled at 11 precipitation sites of differing elevation during a 2‐year period to quantify seasonal stable isotope contributions as a function of elevation. Supplemental stable isotope data collected by the International Atomic Energy Association during a 14‐year period were used to reduce annual variability of the mean seasonal stable isotope data. The stable isotope elevation relationships and local precipitation elevation relationships were combined by using a digital elevation model to calculate the total volumetric contribution of water and stable isotope values as a function of elevation within the basins. The results of these precipitation calculations were compared to measured ground water stable isotope values at the major discharge points near the terminus of the basins. Volumetric precipitation contributions to recharge were adjusted to isolate contributing elevations. This procedure provides an improved representation of recharge contributions within the basins over conventional stable isotope methods. Stable isotope values from wells and springs at the terminus of each basin were used to infer the elevations of precipitation important for recharge of the regional ground water flow system. Ancillary climatic, geologic, and stable isotope values were used to further constrain the location where precipitation is entering the ground water flow system.
Quantitative Interpretation of Specific Conductance Frequency Distributions in Karst
Authors: Massei N , Mahler B.J. , Bakalowicz M. , Fournier M. , Dupont J.P. 
Published: May 2007

AbstractUse of the coefficient of variation (CV) of specific conductance has been a simple and popular approach to classifying karst aquifers; however, problems with this approach arise because specific conductance frequency distributions (CFDs) are usually multimodal and the use of the CV sometimes erroneously classifies aquifers in terms of their dominant flow type or recharge type. Here, we demonstrate a more rigorous analysis of the CFD, which gives insight into the water types contributing to spring flow. The CFD for a water year is separated into an additive series of normal distributions, each related to a hydrogeochemical population. For each water type, its mean, variance, and contribution to the overall CFD can be quantified and compared between water types and water years. We applied this method to 4 years of data collected at Barton Springs, Austin, Texas. Although the overall shape of the CFD changed from year to year, it could consistently be separated into the same set of normally distributed populations. We suggest that each population represents a water type resulting from a particular mode of aquifer functioning. Changes in the parameters describing the curves reflect aquifer response to climatic variations. The results suggest that no single parameter of specific conductance can be used to describe the degree of karst behavior of an aquifer but that the degree of karst behavior itself varies from year to year depending on hydrologic conditions.
Analyzing Bank Filtration by Deconvoluting Time Series of Electric Conductivity
Authors: Cirpka Olaf A. , Fienen Michael N. , Hofer Markus , Hoehn Eduard , Tessarini Aronne , Kipfer Rolf , Kitanidis Peter K. 
Published: May 2007

AbstractKnowing the travel‐time distributions from infiltrating rivers to pumping wells is important in the management of alluvial aquifers. Commonly, travel‐time distributions are determined by releasing a tracer pulse into the river and measuring the breakthrough curve in the wells. As an alternative, one may measure signals of a time‐varying natural tracer in the river and in adjacent wells and infer the travel‐time distributions by deconvolution. Traditionally this is done by fitting a parametric function such as the solution of the one‐dimensional advection‐dispersion equation to the data. By choosing a certain parameterization, it is impossible to determine features of the travel‐time distribution that do not follow the general shape of the parameterization, i.e., multiple peaks. We present a method to determine travel‐time distributions by nonparametric deconvolution of electric‐conductivity time series. Smoothness of the inferred transfer function is achieved by a geostatistical approach, in which the transfer function is assumed as a second‐order intrinsic random time variable. Nonnegativity is enforced by the method of Lagrange multipliers. We present an approach to directly compute the best nonnegative estimate and to generate sets of plausible solutions. We show how the smoothness of the transfer function can be estimated from the data. The approach is applied to electric‐conductivity measurements taken at River Thur, Switzerland, and five wells in the adjacent aquifer, but the method can also be applied to other time‐varying natural tracers such as temperature. At our field site, electric‐conductivity fluctuations appear to be an excellent natural tracer.
Utilization of Decadal Tritium Variation for Assessing the Residence Time of Base Flow
Authors: Rose S. 
Published: May 2007

AbstractAn iterative algorithm is presented that allows the user to model the subsurface residence time of shallow ground water comprising stream base flow based on decadal scale variation of tritium concentrations. The algorithm accounts for the effects of radioactive decay, the shallow subsurface mixing of ground water with precipitation, and ground water flux. The inverse of the best‐fitting modeled flux through the saturated zone is equivalent to the residence time. The data required for this model include at least two measurements of tritium in base flow for a given stream location made at least a decade apart and the long‐term tritium input in precipitation for the region of interest. The model is sensitive to relatively small changes in tritium concentrations and is limited by analytic uncertainties to an accuracy of approximately ±5 years. The algorithm was applied to stream base flow for several basins in the Piedmont Province of Georgia in which tritium concentrations were measured during the early 1990s and again in the 2000s. The model results produced highly concordant residence times for three hydrogeologically similar basins in the Upper Ocmulgee Basin in North Central Georgia. The best estimate of the average residence time for ground water comprising base flow in this Piedmont basin using this new method is between approximately 14 and 18 years. These results are generally consistent with calculations made in previous studies, and these relatively long residence times can be attributed to the storage of water in the clay soils that dominate Piedmont Province watersheds.
A New Method for Laboratory Estimation of the Transverse Dispersion Coefficient
Authors: Massabò Marco , Catania Federico , Paladino Ombretta 
Published: May 2007

AbstractWe introduce a method for identifying the transverse dispersion coefficient in laboratory experiments based on the analytical solution of a pulse injection of a nonreactive solute in a soil column (cylindrical geometry) packed with a homogeneous porous medium. This method takes into account the effect of boundary conditions such as no flux on the column perimeter, and it does not need a priori knowledge of the longitudinal dispersion coefficient. Numerical applications of the method show that it is stable and robust and that the results are reasonably in accordance with those found using the classical maximum likelihood method.
The ‘Malbouffe’ Saga La Saga de la ‘Malbouffe’ Die Saga von „Malbouffe”
Authors: Rérat Alain 
Published: May 2007

summaryThe ‘Malbouffe’ SagaAfter the end of the Second World War, a marked increase in animal and plant production was observed in France, little by little considered by consumers to be obtained at the expense of product quality. The pejorative term ‘malbouffe’ soon emerged, in connection not only with the hygiene of food, but also with its organoleptic and technological characteristics. This article focuses on food safety in France, with special attention paid to the incidence of toxi‐infections and food contaminations of biological and chemical origin. The Mad Cow outbreak is reviewed, along with its consequences for human health in the form of new variant Creutzfeldt‐Jakob's disease. It is emphasized that food‐related human mortality — almost exclusively due to biological contaminations — represented only 647 cases in 1995, i.e., 0.12 per cent of the overall mortality rate. The main contaminants were Salmonella, whose number is steadily decreasing, and Campylobacter, but parasite and phycotoxic risks are increasing. Mortality due to chemical contaminants is very low i.e., 10 cases or 0.002 per cent of overall mortality These contaminants, either accidental (dioxin, hydrocarbons, radioactive isotopes) or unavoidable (residues from phytochemicals, fertilisers) may be at the source of acute or chronic intoxications with sometimes unknown consequences. Nevertheless, food safety in France does not merit the spiteful term ‘malbouffe’.
Two palatal root canals in a maxillary second molar
Authors: De Almeida‐Gomes Fábio , Maniglia‐Ferreira Cláudio , Dos Santos Roberto Alves 
Published: May 2007

AbstractIn this study, we report a case of two palatal root canals in a maxillary second molar that was endodontically treated. The possibility of two palatal root canals in maxillary second molars is quite small; however, it must be taken into account in clinical and radiographic evaluation during endodontic treatment. Often, their presence is noticed only after a canal treatment due to continuing post‐operative discomfort.
Simulation and Analysis of High-Speed Droplet Spray
Dynamics
Authors: Shi H. , Kleinstreuer C. 
Published: May 2007

Abstract
An experimentally validated computer simulation model has been developed for the analysis of gas-phase and droplet characteristics of isothermal sprays generated by pressure jet atomizers. Employing a coupled Euler-Lagrange approach for the gas-droplet flow, secondary droplet breakup (based on the ETAB model), was assumed to be dominant and the k-ε model was selected for simulating the gas flow. Specifically, transient spray formation in terms of turbulent gas flow as well as droplet velocities and size distributions are provided for different back pressures. Clearly, two-way coupling of the phases is important because of the impact of significant gas entrainment, droplet momentum transfer, and turbulent dispersion. Several spray phenomena are discussed in light of low back-pressure (1atm) and high back-pressure (30atm) environments. At low back-pressure, sprays have long thin geometric features and penetrate faster and deeper than at high back-pressures because of the measurable change in air density and hence drag force. Away from the nozzle exit under relatively high back pressures, there is no distinct droplet size difference between peripheral and core regions because of the high droplet Weber numbers, leading to very small droplets which move randomly. In contrast to transient spray developments, under steady-state conditions droplets are subject to smaller drag forces due to the fully-developed gas entrainment velocities which reduce gas-liquid slip. Turbulent dispersion influences droplet trajectories significantly because of the impact of random gas-phase fluctuations.
Objective assessment of childhood adherence to Canadian physical activity guidelines in relation to body composition
Authors: Wittmeier Kristy Diane Marie , Mollard Rebecca Christine , Kriellaars Dean Johannes 
Published: May 2007

Low levels of childhood physical activity (PA) are a contributing factor to obesity. The objective of this study was to determine the adherence of children to PA guidelines in relation to body composition. Body fat (Slaughter equation) and body mass index (BMI) were determined during the school year (n = 251, ages 8–11 y). Daily energy expenditure (EE, kcal·kg–1·d–1) and activity time (AT, min·d–1) above moderate and vigorous intensity thresholds were assessed (accelerometry). Using EE criteria, 35.9% expended < 3.0 kcal·kg–1·d–1, 27.9% expended between 3.0 and 5.9 kcal·kg–1·d–1, 13.5% expended between 6.0 and 7.9 kcal·kg–1·d–1, and 22.9% expended ≥ 8.0 kcal·kg–1·d–1. Using AT criteria, 52.2% accumulated < 30.0 min, 31.1% accumulated 30.0–59.9 min, 12.7% accumulated 60.0–89.9 min, and 4.0% accumulated ≥ 90.0 min of AT. The EE corresponding to accumulation of AT > 90 min was 14.8 kcal·kg–1·d–1. The AT corresponding to ≥ 8 kcal·kg–1·d–1was 73.0 min. Inverse relationships were observed between EE and body fat (p = 0.0004), BMI (p = 0.002), mass (p = 0.008), and fat mass index (FMI) (p = 0.001), as well as between AT and body fat (p = 0.001), BMI (p = 0.008), mass (p = 0.017), and FMI (p = 0.002). Controlling for BMI, FMI was inversely related to EE (p = 0.049) and AT (p = 0.039). Fat-free mass index and AT were positively related (p = 0.038). Physical activity had beneficial effects on body composition for children independent of BMI. The relationship between AT and daily EE guidelines was rationalized (60 min·d–1with 8 kcal·kg–1·d–1) and demonstrated association with acceptable body composition. The 60 min·d–1of moderate activity may be a more suitable initial target than 90 min·d–1, as so few children met the upper tiers of PA guidelines.
Socioeconomic patterns of obesity in Canada: modeling the role of health behaviour
Authors: Ward Heather , Tarasuk Valerie , Mendelson Rena 
Published: May 2007

Among Canadians, previous research has associated obesity with indicators of socioeconomic position. Several health behaviours have demonstrated similar variation, suggesting that social patterning of obesity may be partially explained by behavioural differences. The objective of this study was to examine obesity in relation to income and education among Canadians, and to characterize the indirect associations potentially occurring through fruit and vegetable intake, leisure-time physical activity (LTPA), and smoking. The present secondary analysis of the 2004 Canadian Community Health Survey was restricted to adults (25–64 y) with measured height and weight data (men, n = 3767; women, n = 3823). Interrelationships among socioeconomic indicators, behaviours, and BMI groups were examined by age-adjusted path analysis. For men, obesity was positively associated with income directly and through current smoking. Obesity was also negatively associated with education, directly and through fruit and vegetable intake, and was negatively associated with income through LTPA (r2= 0.17). For women, obesity was negatively associated with education both directly and indirectly through LTPA and with fruit and vegetable intake. No direct association was observed between income and obesity for women, but an indirect negative association existed via LTPA and fruit and vegetable intake (r2= 0.15). The direct and indirect associations between obesity and socioeconomic indicators were consistently inverse among women, but this relationship was not the case in men, suggesting that clearer social patterns of adiposity exist for Canadian women. The limited amount of variance explained by these models likely reflects the complexity of obesity development.
Circulating lipids are lowered but pancreatic islet lipid metabolism and insulin secretion are unaltered in exercise-trained female rats
Authors: Lamontagne Julien , Masiello Pellegrino , Marcil Mariannick , Delghingaro-Augusto Viviane , Burelle Yan , Prentki Marc , Nolan Christopher James 
Published: May 2007

Deteriorating islet β-cell function is key in the progression of an impaired glucose tolerance state to overt type 2 diabetes (T2D), a transition that can be delayed by exercise. We have previously shown that trained rats are protected from heart ischemia–reperfusion injury in correlation with an increase in cardiac tissue fatty-acid oxidation. This trained metabolic phenotype, if induced in the islet, could also prevent β-cell failure in the pathogenesis of T2D. To assess the effect of training on islet lipid metabolism and insulin secretion, female Sprague–Dawley rats were exercised on a treadmill for 90 min/d, 4 d/week, for 10 weeks. Islet fatty-acid oxidation, the expression of key lipid metabolism genes, and glucose-stimulated insulin secretion were determined in freshly isolated islets from trained and sedentary control rats after a 48 h rest period from the last exercise. Although this moderate training reduced plasma glycerol, free fatty acids, and triglyceride levels by about 40%, consistent with reduced lipolysis from adipose tissue, it did not alter islet fatty-acid oxidation, nor the islet expression of key transcription factors and enzymes of lipid metabolism. The training also had no effect on glucose-stimulated insulin secretion or its amplification by free fatty acids. In summary, chronic exercise training did not cause an intrinsic change in islet lipid metabolism. Training did, however, substantially reduce the exposure of islets to exogenous lipid, thereby providing a potential mechanism by which exercise can prevent islet β-cell failure leading to T2D.
Changes in serum cytokines after repeated bouts of downhill running
Authors: Smith Lucille L. , McKune Andrew J. , Semple Stuart J. , Sibanda Emmanuel , Steel Helen , Anderson Ronald 
Published: May 2007

The purpose of this study was to examine changes in serum cytokines after repeated bouts of aerobically biased eccentric exercise. Six untrained males ran down a –13.5% treadmill grade for 60 min on two occasions (RUN1 and RUN2) at a speed equal to 75% of their VO2 peakon a level grade; runs were spaced 14 d apart. Serum was collected before, after, and every hour for 12 h, and every 24 h for 6 d. Cytokines were assessed using 17 multiplex bead technology (Bio-Rad). Creatine kinase (CK) and delayed-onset muscle soreness (DOMS) were assessed before and 24–120 h after. Results were analyzed using a repeated measures analysis of variance (p ≤ 0.05). All comparisons were between RUN1 and RUN2. CK and DOMS were significantly elevated after RUN1 compared with RUN2, indicative of a repeated bout effect. Regarding cytokines, during the initial 12 h period after RUN2, there was a 50% decrease in pro-inflammatory interleukin-6 (IL-6), a 10% decrease in pro-inflammatory macrophage chemotactic protein-1, and a 95% elevation in anti-inflammatory interleukin-10 (IL-10). Regarding 24 h periods, after RUN2 there was an 8% reduction in pro-inflammatory interleukin-8 (IL-8). However, pro-inflammatory macrophage inflammatory factor-1β (MIF-1β) was 18% higher during the 12 h after RUN2. The overall cytokine profile suggests a slight reduction in systemic inflammation after RUN2.
Determination of “Fatmax” with 1 h cycling protocols of constant load
Authors: Meyer Tim , Gäßler Nina , Kindermann Wilfried 
Published: May 2007

Several earlier studies were aimed at determining an exercise intensity that elicits maximal fat oxidation (Fatmax). However, these studies employed few different intensities or used exercise periods of too short a duration. All investigators described intensity with reference to maximal ergometric values, which might lead to metabolically inhomogeneous workloads between individuals. The aim of this study was to determine Fatmaxby overcoming these methodological shortcomings of earlier investigations. Ten healthy recreational athletes (29 ± 5 y; 75 ± 6 kg; 1.81 ± 0.04 m) conducted an initial incremental cycling test to determine VO2 peak(59.2 ± 6.1 mL·min–1·kg–1) and individual anaerobic threshold (IAT; 221 ± 476 W). Within 4 weeks, 5 constant-load tests of 1 h duration were carried out at 55%, 65%, 75%, 85%, and 95% IAT. During all tests indirect calorimetry (MetaMax I, Cortex, Leipzig, Germany) served to quantify fat oxidation. Capillary blood sampling for lactate measurements was conducted every 15 min. All subjects remained in a lactate steady state during the constant load tests, which minimized influences from excess CO2. There was no difference between the 5 intensities for the percentage of energy from fat metabolism (p = 0.12). Additionally, the intensities led to similar absolute amounts of oxidized fat (p = 0.34). However, there was a significant increase in fat metabolism with increasing exercise duration (p = 0.04). It is impossible to define one theoretical optimal intensity for fat oxidation that is true in all individuals. It is thus mandatory to perform an individual assessment with indirect calorimetry. Intra-individual day-to-day variation might render the use of several tests of long duration less applicable than incremental testing with stages of sufficient duration.