bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact of Soil Microstructure Geometry on DRIFT Spectra: Comparisons with Beam Trace Modeling
Authors: Leue M. , Ellerbrock R. H. , Bänninger D. , Gerke H. H.
Published: October 2010

Fourier‐transformed infrared spectroscopy in diffuse reflectance mode (DRIFT) has been proposed as a tool for the characterization of organic matter (OM) composition at intact soil surfaces; however, the local properties and the geometry of intact structural surfaces (e.g., biopores and cracks) affect the reflection in as yet unknown ways. Our goal was to develop an approach to correct for surface geometry effects. The objectives were to analyze the effects of (i) particle size, (ii) porosity, and (iii) specific surface shapes on the infrared signal intensity by comparing measured with simulated reflectance data. Mid‐infrared DRIFT spectra were obtained from differently textured quartz samples and from gypsum blocks with defined surface shapes as models for soil porous systems. A beam tracing model (BTM) was used for the numerical description of the infrared beam propagation in such model soils. The measured DRIFT signal intensity and the simulated bihemispherical reflectance both decreased with increasing quartz particle size; the resolution of the DRIFT spectra decreased with particle size. The geometric effects of the microtopography can be explained by the local variations in the distance between the collection mirror of the DRIFT device and the sample surface. The DRIFT‐measured effects of particle size and surface topography on the signal intensity agreed with the BTM simulation results. The results suggest that a radiative transfer model is useful for interpretations of DRIFT data obtained at intact structural surfaces. The OM properties can be analyzed with DRIFT for surfaces that consist of particles <70 μm and have relatively small, i.e., <1‐mm, relief differences.
Spectroscopic Assessment of Soil Organic Matter in Wetlands from the High Andes
Authors: Segnini Aline , Posadas Adolfo , Quiroz Roberto , Milori Débora Marcondes Bastos Pereira , Saab Sérgio Costa , Neto Ladislau Martin , Vaz Carlos Manoel Pedro
Published: October 2010

Wetlands are valuable for their function as C sinks, water conservation and filtering, flood control, and as a recreational landscape. In the Central and Southern Andes, peatlands (a.k.a., bofedales) are also a source of good quality pastures for wild and domestic South American camelids (Vicugna pacos, Lama glama, and Vicugna vicugna). In the present study, whole soil samples from seasonally and permanently flooded bofedales were analyzed using laser‐induced fluorescence spectroscopy (LIFS) and electron paramagnetic resonance (EPR) to assess soil organic matter (SOM) stability. The results obtained by both techniques were comparable (R2 = 0.88) and proven to be reliable indicators of increased or reduced SOM stability and thus suitable methods for assessing its humification index. The humification values determined in the permanently flooded bofedal were lower than for the seasonally flooded one. Deeper in the soil profiles of both bofedal types, the humification process of SOM attains more advanced stages, with a relative increase of more recalcitrant organic compounds. An important factor is the presence of water in permanently flooded bofedales, which slows down organic matter decomposition due to anaerobiosis. Results from a portable LIFS system also showed significant correlations when compared with both the bench LIFS system (R2 = 0.88) and the EPR (R2 = 0.62). The portable system constitutes an affordable option for the in situ characterization of SOM. This assessment is of outmost importance in agroecosystems acting as green house gases sink or sources under variable climatic conditions.
Synthesis and Characterization of the Hybrid Clay‐Based Material Montmorillonite–Melanoidin: A Potential Soil Model
Authors: Vilas V. Vicente , Mathiasch B. , Huth J. , Kratz J. V. , de la Rosa S. Rubert , Michel P. , Schäfer T.
Published: October 2010

The study of the interactions among metals, minerals, and humic substances is essential in understanding the migration of inorganic pollutants in the geosphere. A considerable amount of organic matter in the environment is associated with clay minerals. To understand the role of organic matter in the environment and its association with clay minerals, a hybrid clay‐based material (HCM), montmorillonite (STx‐1)–melanoidin, was prepared from l‐tyrosine and l‐glutamic acid by the Maillard reaction. The HCM was characterized by elemental analysis, nuclear magnetic resonance, x‐ray photoelectron spectroscopy (XPS), scanning transmission x‐ray microscopy (STXM), and thermal analysis. The presence of organic materials on the surface was confirmed by XPS and STXM. The STXM results showed the presence of organic spots on the surface of the STx‐1 and the characterization of the functional groups present in those spots. Thermal analysis confirmed the existence of organic materials in the montmorillonite interlayer, indicating the formation of a composite of melanoidin and montmorillonite. The melanoidin appeared to be located partially between the layers of montmorillonite and partially at the surface, forming a structure that resembles the way a cork sits on the top of a champagne bottle.
Soil Compaction Reduced the Growth of Lodgepole Pine and Douglas‐fir Seedlings in Raised Beds after Two Growing Seasons
Authors: Bulmer C. E. , Simpson D. G.
Published: October 2010

Growth of lodgepole pine (Pinus contortaDougl. ex Loud. var.latifoliaEngelm.) seedlings after two growing seasons was reduced by medium and high levels of compaction in loamy sand and silt loam soils that received one of three compaction treatments (low = 0.70 relative bulk density [RBD], medium 0.79–0.82 RBD, and high 0.84 RBD). Survival was reduced on the loamy sand, but not on the silt loam. Soil water content was adjusted with irrigation to levels associated with plant water stress (near wilting point), reduced aeration (near 10% air‐filled porosity), and intermediate conditions. Lodgepole pine survival on loamy sand was increased at high water content, but was unaffected by water regime on silt loam. For both soil types, the best lodgepole pine growth was observed for the intermediate watering level. The detrimental effects of compaction were consistent across all water regimes. We also evaluated the response of Douglas‐fir [Pseudotsuga menziesiivar.glauca(Beissn.) Franco] on silt loam and it was similar to lodgepole pine, except that survival was lower on the compacted silt loam, and under dry conditions. For both species, limitations to growth and survival at medium and high compaction levels were consistent with expectations based on the least limiting water range. Our results, however, are also consistent with a continuously declining growth response due to increasing compaction. The RBD was a good predictor of limiting soil conditions for both soil types and species, and substantially reduced survival and growth was observed at RBD levels higher than 0.80.
Transport of Nickel in Different Soils: Column Experiments and Kinetic Modeling
Authors: Liao Lixia , Selim H. M.
Published: October 2010

Kinetic sorption and column miscible displacement transport experiments were performed to quantify the extent of retention and the mobility of Ni in different soils. Results from kinetic sorption indicated that sorption of Ni was time dependent and highly nonlinear, with the sorption affinity of Webster loam (a fine‐loamy, mixed, superactive, mesic Typic Endoaquoll) > Olivier loam (a fine‐silty, mixed, active, thermic Aquic Fraglossudalf) > Windsor sand (a mixed, mesic Typic Udipsamment). A multireaction and transport model (MRTM) was capable of describing the observed nonlinearity and time‐dependent adsorption of Ni for all the soils. Column transport experiments showed that Ni mobility was strongly retarded, with extensive tailing or slow release during leaching. In the Webster soil, breakthrough results revealed that Ni was highly immobile, where <20% of the applied Ni was mobile. In contrast, for the Olivier and Windsor soil columns, 50.4 and 68.3%, respectively, of the applied Ni was recovered in the effluent solution. The MRTM model that accounted for nonlinear reversible kinetics and irreversible reactions is recommended to describe Ni transport in the soils, and incorporation of reversible equilibrium reaction was not necessary. Moreover, the model adequately predicted the Ni distribution with depth in the columns subsequent to pulse application and leaching.
Humic Acid Molecular Weight Estimation by High‐Performance Size‐Exclusion Chromatography with Ultraviolet Absorbance Detection and Refractive Index Detection
Authors: Song Jianzhong , Huang Weilin , Peng Ping'an , Xiao Baohua , Ma Yingjun
Published: October 2010

High‐performance size‐exclusion chromatography (HPSEC) with ultraviolet absorbance detection (UVAD) has been widely utilized to estimate the molecular weight (MW) and MW distribution of humic acids (HAs). The MW estimated by UVAD was inherently inaccurate, however, because UVAD set at 254 nm only detects limited HA components, and the molar absorptivities of different HA constituents are not equal. The objective of this study was to evaluate the refractive index detection (RID)‐based HPSEC method for quantifying the MW of HAs. Five HA samples were quantified with both UVAD and RID. The chromatograms obtained on the two detectors showed that the RID/UVAD response ratios were consistently >10, indicating that RID is more sensitive for the detection of HAs. The chromatograms obtained with RID had three peaks compared with two peaks shown on UVAD chromatograms because RID detected a late‐eluting peak (F3) that was not shown on the UVAD chromatograms. Comparison of the RID/UVAD response ratio showed that the highest MW HA fraction (F1) and lowest MW HA fraction (F3) have higher RID/UVAD response ratios, whereas the medium HA fraction (F2) had a lower RID/UVAD response ratio. These suggested that F1 and F3 may have relatively lower contents of UV‐sensitive bonds such as C=C double bonds than F2 Compared with HPSEC‐UVAD chromatograms, the HPSEC‐RID chromatograms resulted in higher weight‐averaged MWs, lower number‐averaged MWs, and higher polydispersivity for the tested HA samples. This study indicated that RID is less selective than UVAD for detection of structurally highly heterogeneous HA molecules and is thus better for characterizing the MW distribution of HA molecules.
Carbon Sequestration under Irrigated Switchgrass (Panicum virgatumL.) Production
Authors: Collins H.P. , Smith J.L. , Fransen S. , Alva A.K. , Kruger C.E. , Granatstein D.M.
Published: October 2010

Perennial herbaceous crops such as switchgrass are important sources of cellulosic biomass for the developing bioenergy industry. Assessments of how much C will be lost or sequestered into soil and the turnover rates of that C are needed to assist producers and policymakers in determining the long‐term sustainability of biomass production. We used the natural13C abundance of soils to calculate the quantity and turnover of C4−C inputs in irrigated fields cropped to switchgrass monocultures. Soil profile root biomass produced after three seasons averaged 3.9 Mg C ha−1m−1Five years of cropping showed a 1200 kg ha−1increase in soil organic C (SOC) in the 0‐ to 15‐cm depth increment, with no change below 15 cm. The surface 15 cm of soil cropped to ‘Kanlow’ and ‘Shawnee’ had a δ13C enrichment of 3‰ above the native uncultivated soil, with 3.6‰ for ‘Cave in Rock,’ with an average 2‰ enrichment compared with the soil collected before switchgrass establishment. Enrichment in the 30‐ to 60‐ and 60‐ to 90‐cm depths averaged 1.7 and 0.9‰, respectively. The amount of soil profile C4–C determined by δ13C analysis showed a greater C input than determined by the difference in total C mass between the uncultivated native and cropped soils. The average accrual rate of C4–SOC was estimated at 1.0 Mg ha−1yr−1Estimates of the mean residence time of the C3−C under the irrigated C4monocultures of switchgrass were >60 yr in the 0‐ to15‐cm and 30 to 55 yr in the 15‐ to 30‐cm depth increments. On average, 24% of SOC in the 0‐ to 15‐cm depth was derived from C4cropping.
Controlled Traffic Impacts on Physical and Hydraulic Properties in an Intensively Cropped No‐Till Soil
Authors: Blanco-Canqui Humberto , Claassen Mark M. , Stone Loyd R.
Published: October 2010

Changes in soil properties with wheel traffic involving intensive cropping systems under no‐till (NT) are not well understood. We assessed the 8‐yr impacts of intensive cropping systems and wheel traffic on soil physical and hydraulic properties and their relationships under NT on a Ladysmith silty clay loam (a fine, smectitic, mesic Udertic Argiustoll) near Hesston, KS. Winter wheat (Triticum aestivum L.) (W), grain sorghum [Sorghum bicolor (L.) Moench] (S), double‐crop grain sorghum (*S), soybean [Glycine max (L.) Merr.] (B), and double‐crop soybean (*B) arranged in S‐S‐S, W*S‐S‐B, W‐S‐B, and W*B‐S‐B rotations were studied. In doubled crops, sorghum or soybean was planted immediately after wheat harvest. Cropping systems had less of an effect on soil properties than wheel traffic. Wheel traffic increased bulk density (ρb) from 1.16 ± 0.06 (mean ± SD) to 1.38 ± 0.03 Mg m−3, cone index (CI) from 1.78 ± 0.29 to 3.10 ± 0.15 MPa, shear strength (SHEAR) from 23 ± 2.2 to 61 ± 5.2 kPa, and aggregate tensile strength from 377 ± 80 to 955 ± 148 kPa over nontrafficked rows in the 0‐ to 7.5‐cm depth. Wheel compaction reduced cumulative infiltration by 40 to 120 times except in S‐S‐S. It also reduced the logarithm of the saturated hydraulic conductivity (log Ksat), soil water retention at 0 kPa, plant‐available water, effective porosity (ϕe), and the volume of >50‐μm pores. An increase in ρb, CI, and SHEAR linearly reduced ϕe (r > −0.74), which, in turn, reduced cumulative infiltration and log Ksat (r > 0.74). Data strongly support the need for using controlled traffic to reduce the adverse impacts of wheel traffic on soil physical quality.
Quantitative Relationships between Soil Macropore Characteristics and Preferential Flow and Transport
Authors: Luo Lifang , Lin Henry , Schmidt John
Published: October 2010

Quantitative relationships between soil structure, especially macropore characteristics, and soil hydraulic properties are essential to improving our ability to predict flow and transport in structured soils. The objectives of this study were to quantitatively relate macropore characteristics to saturated hydraulic conductivity (Ksat) and dispersivity (λ) and to identify major macropore characteristics useful for estimating soil hydraulic properties under saturated condition. Large intact soil columns were taken from two land uses (cropland and pasture) of the same soil type (a Typic Hapludalf), with four replicates for each land use. The soil columns were scanned using X‐ray computed tomography (CT) to obtain macropore parameters including macroporosity, length density, mean tortuosity, network density, hydraulic radius, path number, node density, and mean angle. The Ksat of the whole soil column, as well as each soil horizon within the column, and solute breakthrough curve (BTC) of CaBr2 were determined for each column. For all eight soil columns studied, macroporosity and path number (the number of independent macropore paths between two boundaries) explained 71 to 75% of the variability in the natural logarithm of Ksat values of the whole soil columns as well as of individual soil horizons. The traditional convection–dispersion equation (equilibrium model) simulated the BTCs well for all soil columns except one with an earthworm hole passing through the entire column, for which the two‐region model (non‐equilibrium model) was required. The path number, hydraulic radius, and macropore angle were the best predictors for λ, explaining 97% of its variability. Correlation between λ of the whole soil columns and Ksat values of the Bt horizons (but not A horizons) implied that the dispersivity was mainly controlled by the horizon with the lowest Ksat in the soil columns. These results indicate that the most useful macropore parameters for predicting flow and transport under saturated condition in structured soils included macroporosity, path number, hydraulic radius, and macropore angle.
Determination of Small‐Scale Spatial Heterogeneity of Water Repellency in Sandy Soils
Authors: Lamparter A. , Bachmann J. , Woche S. K.
Published: October 2010

The degree of water repellency in soils is commonly characterized by the contact angle (CA). For its determination, disturbed and homogenized soil samples are used. Thus, information about the small‐scale spatial heterogeneity of soil water repellency is lost. We modified the sampling technique of the sessile drop method to allow the determination of the CA on particles located at their original positions, reflecting the natural wetting properties of the site. The proposed preparation technique further allows the determination of small‐scale variability of water repellency (millimeter to centimeter scales) along transects with a length of approximately 1 m or more. Hence, the small‐scale spatial distribution of water repellency within a soil profile or transect can be determined and its impact on physical, biological, or chemical processes in soil can be evaluated.
Cadmium Transport in Alkaline and Acidic Soils: Miscible Displacement Experiments
Authors: Elbana Tamer A. , Selim H. M.
Published: October 2010

Transport of heavy metals such as Cd is affected by several rate‐limiting processes including adsorption and release reactions in soils. In this study, column transport and batch kinetic experiments were performed to assess Cd mobility in an acidic (Windsor) and an alkaline (Bustan) soil. Adsorption and desorption isotherms exhibited strong nonlinearity in both soils. A nonlinear multireaction and transport model (MRTM) successfully described adsorption with time as well as adsorption–desorption hysteresis. Breakthrough curves (BTCs) from column experiments indicated strong Cd retardation accompanied by slow release during leaching. The Cd was nearly immobile in the calcareous Bustan surface soil, whereas 20 and 30% of the applied Cd was mobile in the Windsor and Bustan subsurface soil columns. Sequential extractions of soils from the batch and column transport experiments indicated that Cd was associated with carbonates for the alkaline soil and with exchangeable and oxide fractions for the acidic Windsor soil. The MRTM was capable of describing the Cd arrival time in effluent and its concentration during leaching from the soil columns. When the CXTFIT model, which accounts for linear adsorption, was used, adequate overall predictions of the BTCs were obtained including the magnitude and time of peak arrival; however, effluent concentrations at advanced stages of leaching were underestimated. Sorbed Cd based on soil extractions vs. depth at the termination of column experiments were adequately described by the MRTM and CXTFIT.
Percent Relative Cumulative Frequency Approach to Determine Micronutrient Deficiencies in Soybean
Authors: Hitsuda Kiyoko , Toriyama Kazunobu , Subbarao Guntur V. , Ito Osamu
Published: October 2010

Critical micronutrient concentrations in soils and plants have not been clearly determined for marginal soils where deficiencies are likely to occur. The objective of this study was to develop a reliable method for assessing micronutrient deficiency in soils and plants. Soybean plants [Glycine max (L.) Merr.] were grown in the A and B horizons of two Brazilian Ustoxes and watered with a complete nutrient solution (i.e., control) or solutions lacking one of the following micronutrients: Mn, Zn, B, or Cu. Soybean plants were repeatedly grown in the same soils until maturity. The cumulative frequency of deficient plants where the relative seed dry weight was significantly decreased was recorded. The percent relative cumulative frequency (PRCF) is calculated as: cumulative frequency ÷ total number of tested plants × 100. A linear‐plateau regression line was fitted to the PRCF as a function of the micronutrient concentrations in the soil, the uppermost mature leaf, or seed. Critical concentrations (mg kg−1) for deficiency indicated as transition points of regression lines are: 6.4 for Mn (reference), 1.0 for Zn, 0.2 for B, and 0.2 for Cu in the soil (Mehlich‐I extraction for Mn, Zn, and Cu; hot 0.005 mol L−1 BaCl2 extraction for B); 63 for Mn, 34 for Zn, 25 for B, and 4 for Cu in the uppermost mature leaf; 55 for Mn, 42 for Zn, 14 for B, and 5 for Cu in seeds. Thus, this determination method can clearly identify the critical values for micronutrient deficiency in soils and in plant tissues.
Extension of Kozeny‐Carman Model for Estimating Unsaturated Hydraulic Conductivity
Authors: Khaleel Raziuddin
Published: October 2010

We present a predictive model for unsaturated hydraulic conductivity (K) which makes use of the interrelationship among capillary pressure (Pc), wetting phase saturation (Sw), and nonwetting–wetting phase interfacial area. The newly developed model is general so that any closed form Pc–Sw equation can be incorporated. In particular, we formulate Kozeny–Carman–Brooks–Corey (KCBC) and Kozeny–Carman–van Genuchten (KCVG) models by including, respectively, the closed‐form Brooks–Corey and van Genuchten Pc–Sw equations in the modified Kozeny–Carman (KC) model. For Sw ≈ Se, Se is effective saturation, the interfacial area based KCBC equation is identical to the geometrically (wetting phase hydraulic radius) based Brooks–Corey–Burdine (BCB) semi‐empirical model. The capillary pressure thermodynamics are used to describe the KCBC/KCVG relative permeability integrals as well as a variable tortuosity–connectivity, defined as the ratio of interfacial area for a soil sample to the interfacial area for the corresponding, idealized capillary bundle. The new model is tested for a database composed of 22 coarse‐textured and 24 fine‐textured samples. With the decoupling of the relative permeability integrals from the conventional Pc–Sw derived pore‐size distribution models, both KCBC and KCVG formulations provide a good agreement between measured and predicted K for the fine‐ as well as coarse‐textured sediments. The use of the conventional BCB and van Genuchten‐Mualem (VGM) models results in large deviations between measured and predicted K, and considerable bias. To the contrary, for the entire moisture regime, the use of the KCBC and KCVG models produces very little bias and results in a comparable agreement for KCBC and KCVG model predictions with K(θ) measurements. Overall, the modified KC model, with interfacial areas derived from the thermodynamics of Pc, provide an improved description of K(θ) measurements, compared with standard BCB and VGM models.
The Causes and Consequences of Private Food Governance
Authors: Fuchs Doris , Kalfagianni Agni
Published: October 2010

This paper investigates the creation and consequences of private regulation in global food governance. It points to the power to govern and the authority to govern as the two crucial conditions for the emergence and diffusion of private food regulation. More specifically, the paper argues that the power to govern is a function of the structural power of agrifood corporations, particularly retail food corporations in our case. The authority to govern is a function of the perceived legitimacy of retail food corporations as political actors. By linking power and authority to the material and ideational structures existing in the global political economy of food, this paper analyses the processes that serve to create, maintain and reproduce private regulation in food governance. With its analysis, the paper aims to contribute to the theoretical and empirical debates on private authority, private regulation and the challenges for sustainability in the global food system.
Private Regulation and Legal Integration: The European Example
Authors: Cafaggi Fabrizio , Janczuk Agnieszka
Published: October 2010

Private regulation has become a highly debated phenomenon. Previous research has focused mostly on the effectiveness, legitimacy, and governance structure of private regulators at the global level. Few existing analyses have focused on private regulation at the European level, where only questions of interest representation have attracted attention. Analyses of the contribution of private regulation to the process of European legal integration, in particular, are lacking. We seek to fill this gap. From private rules for product safety and for financial markets, such as the Single Euro Payments Area standards, to private rules governing the professions, we observe that private regulation has facilitated and accelerated European legal integration. We argue that in some cases this effect was anticipated, especially by the European Commission, and in those cases the intended effect on European legal integration at least partly explains the rise of private regulation. I other cases, it was an incidental by-product of attempts to address market failures or achieve network legitimacy. In the conclusion, we turn to questions of accountability and legitimacy raised by the increasing importance of private regulators in the Common Market of the EU. Although the EU lacks a body of rules that imposes democratic controls on private regulators, we identify components of European law that can be used as control mechanisms.
Can Technological Innovations Improve Private Regulation in the Global Economy?
Authors: Auld Graeme , Cashore Benjamin , Balboa Cristina , Bozzi Laura , Renckens Stefan
Published: October 2010

Those supplying private regulation in the global economy face two fundamental challenges if they are to ameliorate the problems for which they create these systems: targets must conform to, while demanders must have proof of, regulatory compliance. This paper explores an important area absent from assessments as to whether, when, and how, private regulatory bodies are successful in improving behavior and rewarding compliant firms: the role of technological innovations. Employing an inductive, comparative case study analysis, we offer an analytical framework that distinguishes technological innovations that improve trackingmechanismsfrom innovations that directly improve on-the-groundperformance. We illustrate the utility of the analytical framework through an assessment of technological innovations in shaping “non-state market driven” global certification programs governing forestry, fisheries, coffee, e-waste, and climate.
Regulation and Economic Globalization: Prospects and Limits of Private Governance
Authors: Mayer Frederick , Gereffi Gary
Published: October 2010

Corporate codes of conduct, product certifications, process standards, and other voluntary, non-governmental forms of private governance have proliferated in the last two decades. These innovations are a response to social pressures unleashed by globalization and the inadequacy of governmental institutions for addressing its social and environmental impacts. Private governance has had some notable successes, but there are clear limits to what it alone can be expected to accomplish. We hypothesize that the effectiveness of private governance depends on four main factors: 1) the structure of the particular global value chain in which production takes place; 2) the extent to which demand for a firm's products relies on its brand identity; 3) the possibilities for collective action by consumers, workers, or other activists to exert pressure on producers; and 4) the extent to which commercial interests of lead firms align with social and environmental concerns. Taken together, these hypotheses suggest that private governance will flourish in only a limited set of circumstances. With the trend towards consolidation of production in the largest developing countries, however, we also see a strengthening of some forms of public governance. Private governance will not disappear, but it will be linked to emerging forms of multi-stakeholder institutions.
Renal, Ocular, and Neuromuscular Involvements in Patients with CLDN19 Mutations
Authors: Faguer Stanislas , Chauveau Dominique , Cintas Pascal , Tack Ivan , Cointault Olivier , Rostaing Lionel , Vargas-Poussou Rosa , Ribes David
Published: October 2010

Background and objectives

The objective of this study was to describe the renal and extrarenal findings in patients with recessively inherited familial hypomagnesemia with hypercalciuria and nephrocalcinosis (FHHNC) associated with CLDN19 mutations.

Design, setting, participants, & measurements

Medical records of three patients from two French unrelated families with CLDN19 mutations were retrospectively examined.

Results

Direct sequencing of CLDN19 identified a known variant (p.Gly20Asp) in all patients and a new missense mutation (p.Val44Met) in one (compound heterozygous). The patients' renal phenotype closely mimicked CLDN16-related nephropathy: low serum Mg2+ (<0.65 mmol/L) despite oral supplementation, hypercalciuria partly thiazide-sensitive, and progressive renal decline with ESRD reached at age 16 and 22 years in two individuals. Primary characteristics (failure to thrive, recurrent urinary tract infections, or abdominal pain), age at onset (0.8 to 16 years), and rate of renal decline were highly heterogeneous. Ocular involvement was identified in all patients, although two patients did not have visual loss. Additionally, exercise intolerance with pain, weakness, and electromyographical alterations mimicking a Ca2+/K+ channelopathy (pattern V) were observed in two of three individuals. These features persisted despite the normalization of serum K+ and Mg2+ after renal transplantation.

Conclusions

Ocular manifestations, even subtle, and exercise intolerance mimicking mild to moderate periodic paralysis are two symptoms that need to be searched for in patients with FHHNC and may indicate CLDN19 mutations.
Role of Residual Renal Function in Phosphate Control and Anemia Management in Chronic Hemodialysis Patients
Authors: Penne E. Lars , van der Weerd Neelke C. , Grooteman Muriel P.C. , Mazairac Albert H.A. , van den Dorpel Marinus A. , Nubé Menso J. , Bots Michiel L. , Lévesque Renée , ter Wee Piet M. , Blankestijn Peter J.
Published: October 2010

Background and objectives

There is increasing awareness that residual renal function (RRF) has beneficial effects in hemodialysis (HD) patients. The aim of this study was to investigate the role of RRF, expressed as GFR, in phosphate and anemia management in chronic HD patients.

Design, setting, participants, & measurements

Baseline data of 552 consecutive patients from the Convective Transport Study (CONTRAST) were analyzed. Patients with a urinary output ≥100 ml/24 h (n = 295) were categorized in tertiles on the basis of degree of GFR and compared with anuric patients (i.e., urinary output <100 ml/24 h, n = 274). Relations between GFR and serum phosphate and erythropoiesis-stimulating agent (ESA) index (weekly ESA dose per kg body weight divided by hematocrit) were analyzed with multivariable regression models.

Results

Phosphate levels were between 3.5 and 5.5 mg/dl in 68% of patients in the upper tertile (GFR > 4.13 ml/min per 1.73 m2), as compared with 46% in anuric patients despite lower prescription of phosphate-binding agents. Mean hemoglobin levels were 11.9 ± 1.2 g/dl with no differences between the GFR categories. The ESA index was 31% lower in patients in the upper tertile as compared with anuric patients. After adjustments for patient characteristics, patients in the upper tertile had significantly lower serum phosphate levels and ESA index as compared with anuric patients.

Conclusions

This study suggests a strong relation between RRF and improved phosphate and anemia control in HD patients. Efforts to preserve RRF in HD patients could improve outcomes and should be encouraged.
Contribution of Residual Function to Removal of Protein-Bound Solutes in Hemodialysis
Authors: Marquez Ilian O. , Tambra Shouieb , Luo Frank Y. , Li You , Plummer Natalie S. , Hostetter Thomas H. , Meyer Timothy W.
Published: October 2010

Background and objectives

This study evaluated the contribution of residual function to the removal of solutes for which protein binding limits clearance by hemdialysis.

Design, setting, participants, & measurements

Solute concentrations were measured in 25 hemodialysis patients with residual urea clearances ranging from 0.1 to 6.2 ml/min per 1.73 m2. Mathematical modeling assessed the effect of residual function on time-averaged solute concentrations.

Results

Dialytic clearances of the protein-bound solutes p-cresol sulfate, indoxyl sulfate, and hippurate were reduced in proportion to the avidity of binding and averaged 8 ± 2, 10 ± 3, and 44 ± 13% of the dialytic urea clearance. For each bound solute, the residual clearance was larger in relation to the residual urea clearance. Residual kidney function therefore removed a larger portion of each of the bound solutes than of urea. Increasing residual function was associated with lower plasma levels of p-cresol sulfate and hippurate but not indoxyl sulfate. Wide variation in solute generation tended to obscure the dependence of plasma solute levels on residual function. Mathematical modeling that corrected for this variation indicated that increasing residual function will reduce the plasma level of each of the bound solutes more than the plasma level of urea.

Conclusions

In comparison to urea, solutes than bind to plasma proteins can be more effectively cleared by residual function than by hemodialysis. Levels of such solutes will be lower in patients with residual function than in patients without residual function even if the dialysis dose is reduced based on measurement of residual urea clearance in accord with current guidelines.
Coffee and Caffeine Consumption in Relation to Sex Hormone–Binding Globulin and Risk of Type 2 Diabetes in Postmenopausal Women
Authors: Goto Atsushi , Song Yiqing , Chen Brian H. , Manson JoAnn E. , Buring Julie E. , Liu Simin
Published: October 2010

OBJECTIVE

Coffee consumption has been inversely associated with type 2 diabetes risk, but its mechanisms are largely unknown. We aimed to examine whether plasma levels of sex hormones and sex hormone–binding globulin (SHBG) may account for the inverse association between coffee consumption and type 2 diabetes risk.

RESEARCH DESIGN AND METHODS

We conducted a case-control study nested in the prospective Women's Health Study (WHS). During a median follow-up of 10 years, 359 postmenopausal women with newly diagnosed type 2 diabetes were matched with 359 control subjects by age, race, duration of follow-up, and time of blood draw.

RESULTS

Caffeinated coffee was positively associated with SHBG but not with sex hormones. Multivariable-adjusted geometric mean levels of SHBG were 26.6 nmol/l among women consuming ≥4 cups/day of caffeinated coffee and 23.0 nmol/l among nondrinkers (P for trend = 0.01). In contrast, neither decaffeinated coffee nor tea was associated with SHBG or sex hormones. The multivariable-adjusted odds ratio (OR) of type 2 diabetes for women consuming ≥4 cups/day of caffeinated coffee compared with nondrinkers was 0.47 (95% CI 0.23–0.94; P for trend = 0.047). The association was largely attenuated after further adjusting for SHBG (OR 0.71 [95% CI 0.31–1.61]; P for trend = 0.47). In addition, carriers of rs6259 minor allele and noncarriers of rs6257 minor allele of SHBG gene consuming ≥2 cups/day of caffeinated coffee had lower risk of type 2 diabetes in directions corresponding to their associated SHBG.

CONCLUSIONS

Our findings suggest that SHBG may account for the inverse association between coffee consumption and type 2 diabetes risk among postmenopausal women.
Associations of the Stair Climb Power Test With Muscle Strength and Functional Performance in People With Chronic Obstructive Pulmonary Disease: A Cross-Sectional Study
Authors: Roig Marc , Eng Janice J. , MacIntyre Donna L. , Road Jeremy D. , Reid W. Darlene
Published: October 2010

Background

The Stair Climb Power Test (SCPT) is a functional test associated with leg muscle power in older people.

Objective

The purposes of this study were to compare the results of the SCPT in people with chronic obstructive pulmonary disease (COPD) and people who were healthy and to explore associations of the SCPT with muscle strength (force-generating capacity) and functional performance.

Design

The study was a cross-sectional investigation.

Methods

Twenty-one people with COPD and a predicted mean (SD) percentage of forced expiratory volume in 1 second of 47.2 (12.9) and 21 people who were healthy and matched for age, sex, and body mass were tested with the SCPT. Knee extensor and flexor muscle torque was assessed with an isokinetic dynamometer. Functional performance was assessed with the Timed “Up & Go” Test (TUG) and the Six-Minute Walk Test (6MWT).

Results

People with COPD showed lower values on the SCPT (28%) and all torque measures (∼32%), except for eccentric knee flexor muscle torque. In people with COPD, performance on the TUG and 6MWT was lower by 23% and 28%, respectively. In people with COPD, the SCPT was moderately associated with knee extensor muscle isometric and eccentric torque (r≥.46) and strongly associated (r=.68) with the 6MWT. In people who were healthy, the association of the SCPT with knee extensor muscle torque tended to be stronger (r≥.66); however, no significant relationship between the SCPT and measures of functional performance was found.

Limitations

The observational design of the study and the use of a relatively small convenience sample limit the generalizability of the findings.

Conclusions

The SCPT is a simple and safe test associated with measures of functional performance in people with COPD. People with COPD show deficits on the SCPT. However, the SCPT is only moderately associated with muscle torque and thus cannot be used as a simple surrogate for muscle strength in people with COPD.
Modeling Injury Severity of Multiple Occupants of Vehicles
Authors: Eluru Naveen , Paleti Rajesh , Pendyala Ram M. , Bhat Chandra R.
Published: October 2010

Research to date on crash injury severity has focused on the driver of the vehicle or the most severely injured occupant. Though useful, these studies have not provided injury profiles of all occupants in crash-involved vehicles. This lack of a comprehensive picture has limited the ability to devise measures that enhance the safety and reduce the severity of the injury sustained by all vehicular occupants. Moreover, such studies ignore the possible presence of correlated, unobserved factors that may simultaneously affect the injury severity levels of multiple occupants. This paper aims to fill the gap by presenting a simultaneous model of injury severity to apply to crashes that involve any number of occupants. A copula-based methodology, which could be used to estimate such complex model systems, was applied to a data set of crashes drawn from the 2007 General Estimates System in the United States. The model estimation results provide strong evidence of the presence of correlated unobserved factors that affect injury severity levels of vehicle occupants. The correlation exhibited heterogeneity across vehicle types, with a greater level of interoccupant dependency in heavy SUVs and pickup trucks. The study also sheds light on how numerous exogenous factors—including occupant, vehicle, and crash characteristics; environmental factors; and roadway attributes—affect the injury severity levels of occupants in different seat positions. The findings confirm that rear-seat passengers are less vulnerable to severe injuries than front-row passengers and point to the need to enhance vehicular design features that promote front-row occupant safety.
Getis–Ord Spatial Statistics to Identify Hot Spots by Using Incident Management Data
Authors: Songchitruksa Praprut , Zeng Xiaosi
Published: October 2010

Traditionally, data have been collected to measure and improve the performance of incident management (IM). While these data are less detailed than crash records, they are timelier and contain useful attributes typically not reported in the crash database. This paper proposes the use of Getis–Ord (Gi*) spatial statistics to identify hot spots on freeways from an IM database while selected impact attributes are incorporated into the analysis. The Gi* spatial statistics jointly evaluate the spatial dependency effect of the frequency and attribute values within the framework of the conceptualized spatial relationship. The application of the method was demonstrated through a case study by using the incident database from the Houston, Texas, Transportation Management Center (TranStar). The method successfully identified the clusters of high-impact accidents from more than 30,000 accident records from 2006 to 2008. The accident duration was used as a proxy measure of its impact. The proposed method could be modified, however, to identify the locations with high-valued impacts by using any other attributes, provided that they were either continuous or categorical in nature and could provide meaningful implications. With improved intelligent transportation system infrastructure and communication technology, hot spot analyses performed with IM data of freeway network and arterials in the vicinity have become a much more promising alternative. Freeway management agencies can use the results of hot spot analysis to provide visualized information to aid the decision-making process in the design, evaluation, and management of IM strategies and resources. The limitations of the method and possible future research are discussed in the closing section of the paper.
Investigating Regression to the Mean in Before-and-After Speed Data Analysis
Authors: Park Peter Y. , Lord Dominique
Published: October 2010

Regression to the mean (RTM) in before-and-after speed data is a purely statistical phenomenon that makes random variation in repeated speed measurements from multiple time points before and after the introduction of an engineering treatment look like a genuine speed change brought about by the engineering treatment. This study shows that an observational before-and-after speed data analysis cannot collect speed measurements without measurement error and cannot be free from RTM bias. To obtain accurate estimates of the magnitude of the mean speed change brought about by an engineering treatment, RTM bias needs to be reduced. This study first uses a graphical method to illustrate the RTM phenomenon and then uses numerical examples (with aggregated speed data) to show how to reduce RTM bias in before-and-after speed data analysis. The numerical examples show that the estimated magnitude of the mean speed change that results from the introduction of an engineering treatment or the amount of uncertainty (measured by the estimated standard error and confidence interval) associated with the mean speed change can be misleading if RTM is not taken into account. The paper concludes with suggestions for more rigorous statistical methods, preferably suited for use with disaggregate speed data, that may help to reduce RTM bias in future speed data analysis.
Empirical Investigation of Continuous Logit for Departure Time Choice with Bayesian Methods
Authors: Lemp Jason D. , Kockelman Kara M.
Published: October 2010

Numerous models of travel timing have been calibrated and reported in the literature. Some studies have treated time as a discrete variable by using familiar discrete choice methods, whereas others have treated time in a continuous fashion. Both approaches offer distinct advantages. Here a continuous logit model of work tour departure time choice is estimated; this model offers the advantage of a continuous-time response. A random utility maximization structure is used to capitalize on the key advantages of both main approaches to the modeling of travel timing. Bayesian techniques are used to estimate model parameters, and estimation results suggest a variety of predictive densities for departure times across different individuals. In addition, ordinary least squares regression models are used to estimate travel times and their variance across times of day for the auto and transit modes. These network variables are used to inform estimation of the continuous logit model of departure time. The results are meaningful for multiple applications, and the continuous logit can readily be extended to a two-dimensional choice construct, such that the departure and return times can be modeled simultaneously. In addition, Bayesian estimation techniques allow for the utility function to take any number of forms, which may offer greater predictive ability.
Leverage of Spiral Graph for Transportation System Data Visualization
Authors: VanDaniker Michael
Published: October 2010

Many transportation data sets are saturated with temporal information. Typical examples include data sets concerned with system monitoring, travel time, incident management, and many other temporally aligned features of intelligent transportation systems. Because time is a linear entity, transportation researchers typically plot their temporal data into visualizations that use techniques tailored to linear data sets, such as tables, line charts, and scatter plots. The patterns that temporal data exhibit over time are often more interesting than the linearity of the data, but conventional visualizations often fail to convey them effectively. The spiral graph is a data visualization technique that treats such patterns—and their deviations—as first-class citizens, by allowing for the efficient recognition of the regular cycles in the data. The spiral graph renders data along a temporal axis, which spirals outward at regular intervals. Individual data points are rendered as bands along the axis, creating visual clusters among datum that contribute to patterns. This paper introduces the spiral graph to the transportation community through a series of practical applications and demonstrates best practices to enable researchers to garner more information from their temporal data sets.
Integration of Traffic Simulation into Design Visualization
Authors: Wei Ting , Jarboe Paul
Published: October 2010

Traditionally, design visualization for transportation projects has focused on the transportation facility's appearance. Traffic elements (e.g., vehicles and pedestrians) generally have not been important. With the increasing popularity of three-dimensional (3-D) animation, however, realistic traffic movements are becoming a critical part in design visualization because they effectively illustrate to the public how a transportation facility operates from the perspectives of the driver and the overall system. The public is interested not only in how a system “looks” but also in how it “works.” One challenge facing transportation professionals is how to incorporate realistic traffic movements into a photorealistic visualization. On the one hand, 3-D modeling software that produces photorealistic visualization generally cannot produce realistic traffic movements. On the other hand, traffic simulation software that produces realistic traffic movements generally cannot produce photorealistic visualization. This paper describes a case study in which VISSIM, a microscopic simulation program for multimodal traffic flow, and 3ds Max, a modeling, animation, and rendering package, were used to integrate traffic simulation into a design visualization for the Keystone Avenue Project in Carmel, Indiana. This project involved the upgrade of six at-grade, signalized intersections along Keystone Avenue to six teardrop roundabout interchanges. The case study successfully incorporated realistic traffic movements into a photorealistic visualization through a four-step process. The integration of traffic simulation into design visualization has proved beneficial in combining the strength of 3-D modeling software and traffic simulation software and is likely to be applied further to transportation projects. A few points of guidance are provided to assist future applications.