bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimization of Multiple Transverse Hydraulic Fractures in Horizontal Wellbores
Authors: Meyer Bruce R. , Bazan Lucas W. , Jacot R. Henry , Lattibeaudiere Michael G.
Published: February 2010

Hydraulic fracturing and horizontal drilling are the two key technologies that have made the development of unconventional shale formations economical. Hydraulic fracturing has been the major and relatively inexpensive stimulation method used for enhanced oil and gas recovery in the petroleum industry since 1949. The multi-stage and multicluster per stage fracture treatments in horizontal wellbores create a large stimulated reservoir volume (SRV) that increases both production and estimated ultimate recovery (EUR).

This paper presents a new analytical solution methodology for predicting the behavior of multiple patterned transverse vertical hydraulic fractures intercepting horizontal wellbores. The numerical solution is applicable for finite-conductivity vertical fractures in rectangular shaped reservoirs. The mathematical formulation is based on the method of images with no flow boundaries for symmetrical patterns. An economics procedure is also presented for optimizing transverse fracture spacing and number of fracture stages/clusters to maximize the Net Present Value (NPV) and Discounted Return on Investment (DROI).

The advantages of this approximate analytical production solution for multiple finite-conductivity vertical transverse fractures in horizontal wells and corresponding optimization procedure include: 1) the solution is based on fundamental engineering principles, 2) the production and interference of multiple transverse fractures are predicted to a first-order, and 3) it provides the basis for optimizing fracture and cluster spacing based on NPV and DROI, not just initial production rate. The methodology provides a simple way to predict the production behavior (including interaction) and associated economics of multi-stage/multi-cluster transverse fracture spacing scenarios in horizontal wellbores.

The high initial production (IP) rates from multiple transverse fractures and the late time production decline as a result of fracture interference is discussed. Numerous examples are presented illustrating the method for optimizing (maximizing NPV and DROI) multiple transverse vertical hydraulic fractures in horizontal wellbores.

Application of this technique will help provide the design engineer with a better tool for designing and optimizing multi-stage/multi-cluster transverse hydraulic fractures in horizontal wellbores. The governing production equations and fundamental procedure for NPV and DROI optimization of transverse fractures in a horizontal wellbore are discussed.
Petrophysical Considerations in Evaluating and Producing Shale Gas Resources
Authors: Sondergeld C. H. , Newsham K. E. , Comisky J. T. , Rice M. C. , Rai C. S.
Published: February 2010

We present a practical assessment of petrophysical properties of shales and their measurement in the lab and via logs. Gasbearing shale present unique measurement challenges due to their ultra-low permeability and complicated pore volume connectivity. The combination of low intrinsic permeability and gas sorption effects renders these reservoirs "unconventional". Advances in horizontal drilling and hydraulic stimulation have transformed gas-shale resources into economic reserves. Given their economic significance, there is a strong drive to understand gas shale petrophysical property measurements, both in the laboratory and in the subsurface. We note that various core analysis protocols are used in different laboratories leading to physical property measurements that are inconsistent, even when measured on identical sample sets. In addition, log analysis of kerogen-rich shale is ‘unconventional’ compared to classical techniques used in tight gas sands.

As shale gas evaluation is becoming widely practiced among service companies and operators, we will focus on three reservoir assessment categories: storage capacity (gas-in-place), flow capacity (gas deliverability) and mechanical properties impacting hydraulic stimulation. Within each of these categories we have identified influential petrophysical properties such as rock composition, total organic carbon (TOC) content, porosity, saturation, permeability and mechanical properties. Specifically, we demonstrate the importance of estimating accurate mineral and kerogen content as these properties directly impact rock quality, hydraulic fracturing protocols, and gas-in-place estimations. In reviewing these practices, we also will show the need and possible direction of new technologies that will be required for making evaluations more accurate and quantitative in the future.
An Evaluation of Microseismic Monitoring of Lenticular Tight-Sandstone Stimulations
Authors: Warpinski N. R. , Waltman C. K. , Weijers L.
Published: February 2010

Microseismic monitoring in lenticular tight gas formations has a number of challenging issues associated with both analysis and interpretation. The heterogeneous nature of the reservoir and the typically small microseismic-event amplitudes make it essential to understand the limits of interpretation that should be applied in these reservoirs. With proper care, fracture lengths and azimuth, along with zonal coverage, are readily obtainable. However, fracture-height growth in these complex reservoirs needs to be carefully assessed. Microseismic data provides a level of self-QC potential through the use of a magnitude-distance assessment to guide interpretation and design. Hydraulic fractures observed in these reservoirs tend to be long penetrating fractures that wander through the distributed-sand lenses, with modest height growth in most projects.
Proppant Diagenesis: Results So Far
Authors: LaFollette Randy F. , Carman Paul S.
Published: February 2010

Proppant diagenesis, as a topic of discussion in the industry, tends to generate negative reactions. Potential solutions, such as un-reactive coatings, cost money. Early research was done at substantially higher temperatures than many considered realistic, but was an attempt to shorten test times in order to begin to understand the phenomenon. Regardless of objections and negative reactions, the subject needs to be understood, because long term well performance implications may be significant.

The purpose of this paper is to present a progress report on the results of long-term proppant diagenesis tests using coated and uncoated proppants, with and without shale reservoir rock present in the test cell, and in the presence of fluids of varying composition. Test philosophy and methods are described. Test results are documented using electron micrographs as well as chemical analysis and particle strength tests. Specific changes in fluid chemistry that result from contact with proppant and shale at reservoir temperature will also be a focus of the paper.
Developing Effective and Environmentally Suitable Fracturing Fluids Using Hydraulic Fracturing Flowback Waters
Authors: Blauch M. E.
Published: February 2010

This paper presents methods, materials, and procedures that can enable operators to prepare safe and effective fracturing fluids from returned fracturing fluid (commonly called "flowback") and produced formation water. Reuse of frac fluid and formation water especially focused on high volume and rate (HVR) fracturing requires establishment of a number of interrelated chemical and geochemical solutions. Specifically addressed are environmental attributes of the chemical additive components and whole fluid, geochemical precipitates, scale, microbially induced biogeochemical interactions, water analysis, friction reducer compatibilities, and saline content.

Materials discussed in the paper include: Friction reducer chemistry and attributes that enable reuse of frac water in actual flowbacks from shale reservoirs.Solutions and need for complexing iron and converting to insoluble precipitates that can damage fracture conductivity, reduce production potential, and negatively impact scale inhibition.Methods for protection against an assemblage of naturally occurring geochemical precipitates.A solution for environmentally sound quick-kill of microorganisms responsible for producing damaging downhole biogeochemical byproducts, including hydrogen sulfide.

Fracture-stimulation of shale-gas wells requires an enormous volume of frac fluid, which traditionally has been developed from fresh water purchased from sources near the drilling location or municipalities. Along with the chemicals introduced by the frac fluid, the flowback may contain a wide variety of dissolved constituents such as salts and metal ions. The constituents can make wastewater disposal environmentally prohibitive, difficult, and expensive, and may impair gas production by placing damaging precipitates within the fracture, perforations, and wellbore. The paper presents and discusses practical, cost-effective remediation of frac fluid to minimum standards required to achieve environmental, technical, and economic goals. Keys to successful reuse of frac fluids are chemical additive developments and processes involving analysis of water chemistry, flow-loop testing, and geochemical modeling in the establishment of treatment and/or dilution standards to enable fracturing fluid reuse.
Microbial Atrazine Breakdown in a Karst Groundwater System and Its Effect on Ecosystem Energetics
Authors: Iker Brandon C. , Kambesis Pat , Oehrle Stuart A. , Groves Chris , Barton Hazel A.
Published: February 2010

In the absence of sunlight energy, microbial community survival in subterranean aquifers depends on integrated mechanisms of energy and nutrient scavenging. Because karst aquifers are particularly sensitive to agricultural land use impacts due to rapid and direct hydrologic connections for pollutants to enter the groundwater, we examined the fate of an exogenous pesticide (atrazine) into such an aquifer and its impact on microbial ecosystem function. Atrazine and its degradation product deethylatrazine (DEA) were detected in a fast‐flowing karst aquifer underlying atrazine‐impacted agricultural land. By establishing microbial cultures with sediments from a cave conduit within this aquifer, we observed two distinct pathways of microbial atrazine degradation: (i) in cave sediments previously affected by atrazine, apparent surface‐derived catabolic genes allowed the microbial communities to rapidly degrade atrazine via hydroxyatrazine, to cyanuric acid, and (ii) in low‐impact sediments not previously exposed to this pesticide, atrazine was also degraded by microbial activity at a much slower rate, with DEA as the primary degradation product. In sediments from both locations, atrazine affected nitrogen cycling by altering the abundance of nitrogen dissimulatory species able to use nitrogenous compounds for energy. The sum of these effects was that the presence of atrazine altered the natural microbial processes in these cave sediments, leading to an accumulation of nitrate. Such changes in microbial ecosystem dynamics can alter the ability of DEA to serve as a proxy for atrazine contamination and can negatively affect ecosystem health and water quality in karst aquifers.
Modeling Nitrate Leaching and Optimizing Water and Nitrogen Management under Irrigated Maize in Desert Oases in Northwestern China
Authors: Hu Kelin , Li Yong , Chen Weiping , Chen Deli , Wei Yongping , Edis Robert , Li Baoguo , Huang Yuanfang , Zhang Yuanpei
Published: February 2010

Understanding water and N transport through the soil profile is important for efficient irrigation and nutrient management to minimize nitrate leaching to the groundwater, and to promote agricultural sustainable development in desert oases. In this study, a process‐based water and nitrogen management model (WNMM) was used to simulate soil water movement, nitrate transport, and crop growth (maize [Zea mays L.]) under desert oasis conditions in northwestern China. The model was calibrated and validated with a field experiment. The model simulation results showed that about 35% of total water input and 58% of the total N input were leached to <1.8 m depth under traditional management practice. Excessive irrigation and N fertilizer application, high nitrate concentration in the irrigation water, together with the sandy soil texture, resulted in large nitrate leaching. Nitrate leaching was significantly reduced under the improved management practice suggested by farm extension personnel; however, the water and nitrate inputs still far exceeded the crop requirements. More than 1700 scenarios combining various types of irrigation and fertilizer practices were simulated. Quantitative analysis was conducted to obtain the best management practices (BMPs) with simultaneous consideration of crop yield, water use efficiency, fertilizer N use efficiency, and nitrate leaching. The results indicated that the BMPs under the specific desert oasis conditions are to irrigate the maize with 600 mm of water in eight times with a single fertilizer application at a rate of 75 kg N ha−1
A Comparative Study of Phosphate Sorption in Lowland Soils under Oxic and Anoxic Conditions
Authors: Heiberg Lisa , Pedersen Thomas Vils , Jensen Henning S. , Kjaergaard Charlotte , Hansen Hans Christian Bruun
Published: February 2010

Phosphate (Pi) release due to FeIII oxide dissolution is well documented for soils undergoing reduction. The Pi sorption properties of soils in anoxic conditions are, however, still under consideration. In this investigation, Pi sorption to strictly anoxic soils was compared with oxic conditions to assess the potential of lowland soils to function as traps for Pi when flooded with drainage water. Batch sorption experiments were performed on seven minerogenic soils. Sorption to the anoxic soils was conducted after anoxic incubation, resulting in reduction of 36 to 93% of the dithionite‐extractable FeIII (FeBD). Langmuir fitted Pi sorption isotherms showed a Pi release of up to 1.1 mmol kg−1 in six soils when Pi concentrations in the matrix (Psol) were lower than 10 μM. Phosphate desorption was attributed to dissolution of amorphous iron oxides, and higher pH under anoxic conditions. The point of zero net sorption (EPC0) increased 2‐ to 10‐fold on reduction. Five soils showed higher Pi sorption capacities in the anoxic than in the oxic state at higher Psol concentrations. Solubility calculations indicated that precipitation of vivianite or similar FeII phosphates may have caused the higher sorption capacities. Use of maximum sorption capacity (Smax) is therefore misleading as a measure of Pi sorption at low Psol concentrations. The results demonstrate that none of the strongly anoxic soils, irrespective of the initial FeIII oxide content, the P saturation, and the degree of FeIII oxide reduction, could retain Pi at natural Psol concentrations in agricultural drainage water.
Sorptive Removal of Trinitroglycerin (TNG) from Water Using Nanostructured Silica‐based Materials
Authors: Saad Rabih , Thibutot Sonia , Ampleman Guy , Hawari Jalal
Published: February 2010

Trinitroglycerin (TNG), a nitrate ester, is widely used in the pharmaceutical industry for the treatment of angina pectoris (chest pain) and by the military for the manufacturing of dynamite and propellants. Currently, TNG is considered as a key environmental contaminant due to the discharge of wastewater tainted with the chemical from various military and pharmaceutical industries. The present study describes the use of a nanostructured silica material (Mobil Composite Material no. 48 [MCM‐48]) prepared by mixing tetraethylorthosilicate (TEOS) and cetyltrimethylammonium bromide (CTAB) to remove TNG from water. The sorption of TNG onto MCM‐48 rapidly reached equilibrium within 1 h. Sorption kinetics were best described using a pseudo‐second order model, whereas sorption isotherms were best interpreted using the Langmuir model. The latter gave a maximum sorption capacity of 55.2 mg g−1 at 40°C. The enthalpy and entropy of TNG sorption onto MCM‐48 were 1.89 kJ mol−1 and 79.0 J mol−1K−1, indicating the endothermic nature of the TNG sorption onto MCM‐48. When MCM‐48 was heated at 540°C for 5 h, the resulting calcined material (absence of the surfactant) did not sorb TNG, suggesting that the surfactant component of the nanomaterial was responsible for TNG sorption. Finally, we found that MCM‐48 lost approximately 30% of its original sorption capacity after five sorption–desorption cycles. In conclusion, the nanostructured silica based sorbent, with high sorption capacity and remarkable reusability, should constitute the basis for the development of an effective technology for the removal of TNG from contaminated water.
Parameter Importance and Uncertainty in Predicting Runoff Pesticide Reduction with Filter Strips
Authors: Muñoz‐Carpena Rafael , Fox Garey A. , Sabbagh George J.
Published: February 2010

Vegetative filter strips (VFS) are an environmental management tool used to reduce sediment and pesticide transport from surface runoff. Numerical models of VFS such as the Vegetative Filter Strip Modeling System (VFSMOD‐W) are capable of predicting runoff, sediment, and pesticide reduction and can be useful tools to understand the effectiveness of VFS and environmental conditions under which they may be ineffective. However, as part of the modeling process, it is critical to identify input factor importance and quantify uncertainty in predicted runoff, sediment, and pesticide reductions. This research used state‐of‐the‐art global sensitivity and uncertainty analysis tools, a screening method (Morris) and a variance‐based method (extended Fourier Analysis Sensitivity Test), to evaluate VFSMOD‐W under a range of field scenarios. The three VFS studies analyzed were conducted on silty clay loam and silt loam soils under uniform, sheet flow conditions and included atrazine, chlorpyrifos, cyanazine, metolachlor, pendimethalin, and terbuthylazine data. Saturated hydraulic conductivity was the most important input factor for predicting infiltration and runoff, explaining >75% of the total output variance for studies with smaller hydraulic loading rates (∼100–150 mm equivalent depths) and ∼50% for the higher loading rate (∼280‐mm equivalent depth). Important input factors for predicting sedimentation included hydraulic conductivity, average particle size, and the filter's Manning's roughness coefficient. Input factor importance for pesticide trapping was controlled by infiltration and, therefore, hydraulic conductivity. Global uncertainty analyses suggested a wide range of reductions for runoff (95% confidence intervals of 7–93%), sediment (84–100%), and pesticide (43–100%) . Pesticide trapping probability distributions fell between runoff and sediment reduction distributions as a function of the pesticides' sorption. Seemingly equivalent VFS exhibited unique and complex trapping responses dependent on the hydraulic and sediment loading rates, and therefore, process‐based modeling of VFS is required.
Effects of Domestic Sewage Water and Ameliorant Effectiveness on Soil Hydraulic Conductivity
Authors: Li Fa Hu , Yang Sheng Min , Peng Chong
Published: February 2010

Irrigation with domestic sewage water is a normal practice in developing countries, and its possible adverse effects on soil hydraulic conductivity are important for sustainable farmland management. The objective of this study was to assess (i) the influences of untreated raw domestic sewage water irrigation on hydraulic conductivity, and (ii) the effectiveness of soil ameliorants at various soil sodicity levels. The saturated hydraulic conductivity for soils that were equilibrated with Na adsorption ratios (SARs) of 0, 10, 20, and 30 (mmolc L−1)1/2 was measured in a laboratory under constant‐head ponding with raw domestic sewage water following gypsum and polyacrylamide application at rates of 5 and 0.1 g kg−1 soil, respectively. Compared with distilled water, raw domestic sewage water decreased the hydraulic conductivity of nonsodic soil but increased that of sodic soils. The influence of soil sodicity on hydraulic conductivity decreased under domestic sewage water. Additionally, gypsum application decreased leachate pH by about 0.5 pH units and increased hydraulic conductivity by up to 180%, with the exception of soil with a SAR of 20. In that case, the hydraulic conductivity decreased by about 50%. The influence of gypsum on hydraulic conductivity decreased with increasing soil sodicity levels. Application of gypsum by spreading generally resulted in a slightly greater leachate electrical conductivity and hydraulic conductivity than its application by mixing. Polyacrylamide application decreased leachate pH by 0.5 to 1.0 units and slightly decreased hydraulic conductivity. The adverse effect of domestic sewage water irrigation on soil hydraulic conductivity generally can be inhibited or ameliorated by gypsum application.
A Rapid Assay to Estimate Soil Microbial Biomass Potassium in Agricultural Soils
Authors: Lorenz Nicola , Verdell Kenneth , Ramsier Cliff , Dick Richard P.
Published: February 2010

Various assays for microbial biomass C (Cmic) and other elements in the soil are available but there are none for microbial biomass K (Kmic). Our objective was to develop a rapid chloroform‐fumigation extraction (CFE) assay to estimate KmicThe extractants ammonium acetate (CH3COONH4) and sodium hydrogen carbonate (NaHCO3) were tested at three molarities on a Hoytville clay. A 1 mol L−1CH3COONH4yielded the highest levels of extractable K. To calibrate the CFE efficiency forKmic, bacteria and fungi isolated from soils were cultured, suspended, and mixed with three soils of different texture: a fine sand, a silt loam, or a clay. The known concentrations ofKmicin the inoculum served as a basis to calculate the microbial biomass K conversion factors (kEK) for the three soils tested. Soils from corn (Zea maysL.) fields in Ohio under no‐till, minimum tillage, and plow tillage hadKmicvalues ranging from 68 to 179 mg K kg−1TheKmicvalue was highest in the silt loam under no‐till and in the clay soil under minimum tillage. Soil exchangeable K (Kexch) and nonexchangeable K (Knexch) did not correlate withKmic, but with total C. On average,Kexchwas 2.7 andKnexch8.3 times higher thanKmicThe data presented in this study are based on an initial study, and more soils and ecosystems need to be evaluated before the method can be generally adopted for soil samples. Our study shows, however, thatKmicis a significant K pool in soils that has been overlooked in the past.
Greenhouse Gas Emission from Contrasting Management Scenarios in the Northern Corn Belt
Authors: Johnson Jane M. F. , Archer David , Barbour Nancy
Published: February 2010

The agricultural sector is a small but significant contributor to the overall anthropogenic greenhouse gas (GHG) emission and a major contributor of N2O emission in the United States. Land management practices or systems that reduce GHG emission would aid in slowing climate change. We measured the emission of CO2, CH4, and N2O from three management scenarios: business as usual (BAU), maximum C sequestration (MAXC), and optimum greenhouse gas benefits (OGGB). The BAU scenario was chisel or moldboard plowed, fertilized, in a 2‐yr rotation (corn [Zea mays L.]–soybean [Glycine max (L.) Merr.]). The MAXC and OGGB scenarios were strip tilled in a 4‐yr rotation (corn–soybean–wheat [Triticum aestivum L.]/alfalfa [Medicago sativa L.]–alfalfa). The MAXC received fertilizer inputs but the OGGB scenario was not fertilized. Nitrous oxide, CO2, and CH4 emissions were collected using vented static chambers. Carbon dioxide flux increased briefly following tillage, but the impact of tillage was negligible when CO2 flux was integrated across an entire year. The soil tended to be neutral to a slight CH4 sink under these managements scenarios. The N2O flux during spring thaw accounted for up to 65% of its annual emission, compared with 6% or less due to application of N fertilizer. Annual cumulative emissions of CO2, CH4, and N2O did not vary significantly among these three management scenarios. Reducing tillage and increasing the length of the crop rotation did not appreciably change GHG emissions. Strategies that reduce N2O flux during spring thaw could reduce annual N2O emission.
Simulating Soil Organic Carbon Dynamics with Residue Removal Using the CQESTR Model
Authors: Gollany H. T. , Novak J. M. , Liang Y. , Albrecht S. L. , Rickman R. W. , Follett R. F. , Wilhelm W. W. , Hunt P. G.
Published: February 2010

Concerns about CO2emissions and fossil fuel supplies have enhanced interest in using crop residues for biofuel production; however, maintaining soil organic C (SOC) through residue return is vital for maintaining soil productivity. Our objectives were to simulate long‐term SOC dynamics using CQESTR and to examine the effect of residue harvest on SOC stocks under disking (DT) and conservation tillage (CS). A long‐term study in the mid‐Coastal Plain region of South Carolina was used to simulate four residue harvest rates (0, 50, 66, and 90%) during two harvest periods. The yearly variation of SOC was predicted well (r2= 0.84,P< 0.0001). Without residue removal, average increases of 0.10 and 0.39 g SOC kg−1yr−1were predicted under DT and CS, respectively, consistent with observed increases of 0.12 and 0.44 g SOC kg−1yr−1After 23 yr, simulated SOC stock gain was more than threefold greater under CS than DT (9.0 vs. 2.4 g SOC kg−1). The model predicted 1.86 and 4.47 g SOC kg−1losses in the top 5 cm of soil under DT and CS, respectively, during 23 yr of 66% residue harvest compared with no residue harvest. The predicted SOC stocks under CS were ∼5 g SOC kg−1greater than under DT, however, even with 90% residue harvest. The quantities of crop residue that can be sustainably harvested were directly influenced by the initial SOC concentration and tillage practices. While CS can somewhat mitigate the loss of soil C, residue harvest from loamy sand soils may have an adverse impact on SOC stocks.
Nitrous Oxide and Carbon Dioxide Emissions Following Green Manure and Compost Fertilization in Corn
Authors: Alluvione Francesco , Bertora Chiara , Zavattaro Laura , Grignani Carlo
Published: February 2010

Alternative N fertilizers that stimulate low greenhouse gas emissions from soil are needed to reduce the impact of agriculture on global warming. Corn (Zea mays L.) grown in a calcareous silt loam soil in northwestern Italy was fertilized with a municipal solid waste compost and vetch (Vicia villosa Roth.) green manure. Their potential to reduce N2O and CO2 emissions was compared with that of urea (130 kg N ha−1). Gaseous fluxes were measured for 2 yr in the spring (after soil incorporation of fertilizers) and in summer. In spring, the slow mineralization of compost reduced N2O emissions (0.11% of supplied N) relative to urea (3.4% of applied N), without an increase in CO2 fluxes. Nitrous oxide (2.31% of fixed N) and CO2 emissions from rapid vetch decomposition did not differ from urea. When N2O and CO2 fluxes were combined, compost reduced by 49% the CO2 equivalent emitted following urea application. Vetch did not show such an effect. In summer, no fertilizer effect was found on N2O and CO2 emissions. Compost proved to be potentially suitable to reduce the CO2 equivalent emitted after soil incorporation while vetch did not. For a thorough evaluation, net greenhouse gas emissions assessment should be extended to the entire N life cycle. Differences between calculated N2O emission factors and the default Tier 1 value of the Intergovernmental Panel on Climate Change (1%) confirmed the need for site‐ and fertilizer‐specific estimations.
Polymer‐Coated Urea Maintains Potato Yields and Reduces Nitrous Oxide Emissions in a Minnesota Loamy Sand
Authors: Hyatt Charles R. , Venterea Rodney T. , Rosen Carl J. , McNearney Matthew , Wilson Melissa L. , Dolan Michael S.
Published: February 2010

Irrigated potato (Solanum tuberosum L.) production requires large inputs of N, and therefore has high potential for N loss including emissions of N2O. Two strategies for reducing N loss include split applications of conventional fertilizers, and single applications of polymer‐coated urea (PCU), both of which aim to better match the timing of N availability with plant demand. The objective of this 3‐yr study was to compare N2O emissions and potato yields following a conventional split application (CSA) using multiple additions of soluble fertilizers with single preplant applications of two different PCUs (PCU‐1 and PCU‐2) in a loamy sand in Minnesota. Each treatment received 270 kg of fertilizer N ha−1 per season. An unfertilized control treatment was included in 2 of 3 yr. Tuber yields did not vary among fertilizer treatments, but N2O emissions were significantly higher with CSA than PCU‐1. During 3 consecutive yr, mean growing season emissions were 1.36, 0.83, and 1.13 kg N2O‐N ha−1 with CSA, PCU‐1, and PCU‐2, respectively, compared with emissions of 0.79 and 0.42 kg N2O‐N ha−1 in the control. The PCU‐1 released N more slowly during in situ incubation than PCU‐2, although differences in N2O emitted by the two PCUs were not generally significant. Fertilizer‐induced emissions were relatively low, ranging from 0.10 to 0.15% of applied N with PCU‐1 up to 0.25 to 0.49% with CSA. These results show that N application strategies utilizing PCUs can maintain yields, reduce costs associated with split applications, and also reduce N2O emissions.
Biologic Origin of Iron Nodules in a Marine Terrace Chronosequence, Santa Cruz, California
Authors: Schulz Marjorie S. , Vivit Davison , Schulz Charles , Fitzpatrick John , White Art
Published: February 2010

The distribution, chemistry, and morphology of Fe nodules were studied in a marine terrace soil chronosequence northwest of Santa Cruz, California. The Fe nodules are found at depths <1 m on all terraces. The nodules consisted of soil mineral grains cemented by Fe oxides. The nodules varied in size from 0.5 to 25 mm in diameter. Nodules did not occur in the underlying regolith. The Fe‐oxide mineralogy of the nodules was typically goethite; however, a subset of nodules consisted of maghemite. There was a slight transformation to hematite with time. The abundance of soil Fe nodules increased with terrace age on the five terraces studied (aged 65,000–226,000 yr). Scanning electron microscopy (SEM) revealed Fe‐oxide‐containing fungal hyphae throughout the nodules, including organic structures incorporating fine‐grained Fe oxides. The fine‐grained nature of the Fe oxides was substantiated by Mössbauer spectroscopy. Our microscopic observations led to the hypothesis that the nodules in the Santa Cruz terrace soils are precipitated by fungi, perhaps as a strategy to sequester primary mineral grains for nutrient extraction. The fungal structures are fixed by the seasonal wetting and dry cycles and rounded through bioturbation. The organic structures are compacted by the degradation of fungal C with time.
Laboratory versus Field Calibration of Capacitance Probes
Authors: Gabriel José Luis , Lizaso Jon I. , Quemada Miguel
Published: February 2010

Capacitance probes (CP) based on responses to electromagnetic properties in soil are widely used for monitoring soil volumetric water content (θv), but proper calibration is necessary to obtain reliable results. The objectives of this study were to: (i) compare errors in evaluating θv when using soil‐specific equations as opposed to the manufacturer's default equation; (ii) compare the CP calibration equations obtained in the laboratory and in the field; and (iii) evaluate the accuracy of CP under field conditions using soil‐specific equations as opposed to the manufacturer's default equation. Laboratory and field calibrations were conducted by fitting statistical relationships between readings from CP and θv measured from soil cores. The accuracies of the obtained calibration equations were evaluated under field conditions during two irrigation cycles. In both calibration studies, the manufacturer's default equation consistently overcalculated θv (RMSE > 0.044 m3 m−3), whereas custom CP calibration equations provided accurate θv determinations (RMSE < 0.028 m3 m−3). Even when θv was overestimated, the manufacturer's default equation was able to reproduce θv dynamics during irrigation. Therefore, if users are interested in relative differences in θv, they may use the manufacturer's default equation. If absolute values are needed, however, soil‐specific calibration is required. The accuracy of CP in monitoring θv under field conditions was slightly better using the laboratory calibration equation (RMSE = 0.019 m3 m−3) rather than the field calibration equation (RMSE = 0.023 m3 m−3). The use of a laboratory calibration is recommended given that it is easily reproducible, facilitates work planning, and minimizes uncertainties.
Growing the Soil Science Profession through Investment, Vestment, and Validation
Authors: Ferris Dawn R. , Hattey Jeffory A. , Mullen Michael D.
Published: February 2010

Soil scientists have invested in their profession through the development of performance objectives, national exams, and recognized state licensing and certification processes. These activities have defined the practice of soil science, thus providing society, other professionals, and the scientific community with a more comprehensive understanding of what types of work soil scientists perform as well as assurances of the competency of practitioners. Along with defining the practice, efforts must be strengthened to educate the next generation of soil scientists and provide them with opportunities to become vested in the profession. Higher education must also validate student learning through an assessment process to evaluate the preparation of students to perform at standards set by the profession. The mechanisms are in place to promote the soil science profession using established professional standards and ethics, education and experience criteria, examination for licensing or certification, and continuing education requirements. Soil scientists must continue to emphasize the importance of soils to society, to colleagues in other professions, and to students of all ages to further expand opportunities for investment, vestment, and validation of the soil science profession.
Clay Mineralogy in Arctic Tundra Gelisols, Northern Alaska
Authors: Borden Patrick W. , Ping Chien-Lu , McCarthy Paul J. , Naidu Sathy
Published: February 2010

Little is understood about chemical weathering processes in Alaskan arctic soils, where moisture is generally not limited but acidity varies and the average soil temperature is close to or below freezing. Weathering reactions in soil convert primary minerals into secondary clay minerals. Silty loam textured soils from three sites in moist acidic tundra (MAT) and three sites in moist nonacidic tundra (MNT) in the northern Arctic Foothills, Alaska, were characterized with emphasis on the origin of the clay minerals. The MNT soils had a discontinuous and thinner organic layer, which leads to a deeper summer thaw and greater cryoturbation than the MAT soils. The MNT had higher cation exchange capacity and base saturation than MAT. These buffer against acidification and account for the pH differences of MAT and MNT. Other chemical characteristics including C and N content as well as Fe and Al were similar (by horizon) across the MAT/MNT boundary. X‐ray diffraction of coarse (0.0002–0.002 mm) and fine clay (<0.0002 mm) fractions indicate that illite, vermiculite, and kaolinite are the predominant clay minerals. Presumably, kaolinite is detrital and vermiculite is weathered from illite. The proportion of vermiculite to illite is higher in MAT and the illite to vermiculite proportion is higher in MNT. This shows that soil acidity does affect weathering processes despite the low soil temperature.
The WRF Model Forecast-Derived Low-Level Wind Shear Climatology over the United States Great Plains
Authors: Storm Brandon , Basu Sukanta
Published: February 2010

For wind resource assessment projects, it is common practice to use a power-law relationship (U(z) ~ zα) and a fixed shear exponent (α = 1=7) to extrapolate the observed wind speed from a low measurement level to high turbine hub-heights. However, recent studies using tall-tower observations have found that the annual average shear exponents at several locations over the United States Great Plains (USGP) are significantly higher than 1=7. These findings highlight the critical need for detailed spatio-temporal characterizations of wind shear climatology over the USGP, where numerous large wind farms will be constructed in the foreseeable future. In this paper, a new generation numerical weather prediction model—the Weather Research and Forecasting (WRF) model, a fast and relatively inexpensive alternative to time-consuming and costly tall-tower projects, is utilized to determine whether it can reliably estimate the shear exponent and the magnitude of the directional shear at any arbitrary location over the USGP. Our results indicate that the WRF model qualitatively captures several low-level wind shear characteristics. However, there is definitely room for physics parameterization improvements for the WRF model to reliably represent the lower part of the atmospheric boundary layer.
The Influence of Secondhand Smoke Exposure on Birth Outcomes in Jordan
Authors: Abu-Baker Nesrin N. , Haddad Linda , Savage Christine
Published: February 2010

This study investigates how secondhand smoke (SHS) exposure influences neonatal birth weight in Jordan, a country with high smoking prevalence. The findings revealed that as the average number of SHS exposure hours per week increased in the second trimester, the neonatal birth weight decreased while holding all covariates constant. Women who reported a higher average number of SHS exposure hours per week from work in the second trimester, home in the third trimester, and outside in the third trimester were at greater risk for having a low birth weight neonate than women who reported a lower average number of SHS exposure hours.
Materials for Powder-Based AC-Electroluminescence
Authors: Bredol Michael , Schulze Dieckhoff Hubert
Published: February 2010

At present, thick film (powder based) alternating current electroluminescence (AC-EL) is the only technology available for the fabrication of large area, laterally structured and coloured light sources by simple printing techniques. Substrates for printing may be based on flexible polymers or glass, so the final devices can take up a huge variety of shapes. After an introduction of the underlying physics and chemistry, the review highlights the technical progress behind this development, concentrating on luminescent and dielectric materials used. Limitations of the available materials as well as room for further improvement are also discussed.
Asymmetry and Symmetry in the Beauty of Human Faces
Authors: Zaidel Dahlia W. , Hessamian Marjan
Published: February 2010

The emphasis in the published literature has mostly been on symmetry as the critical source for beauty judgment. In fact, both symmetry and asymmetry serve as highly aesthetic sources of beauty, whether the context is perceptual or conceptual. The human brain is characterized by symbolic cognition and this type of cognition facilitates a range of aesthetic reactions. For example, both art and natural scenery contain asymmetrical elements, which nevertheless render the whole effect beautiful. A further good case in point is, in fact, human faces. Normally, faces are structurally left-right symmetrical content-wise but not size-wise or function-wise. Attractiveness has often been discussed in terms of content-wise full-face symmetry. To test whether or not attractiveness can be gleaned only from the presence of left-right full-faces we tested half faces. Three separate groups of participants viewed and rated the attractiveness of 56 full-faces (women’s and men’s), their 56 vertical left hemi-faces and 56 vertical right hemi-faces. We found no statistically significant differences in the attractiveness ratings of full- and hemi-faces (whether left or right). Instead, we found a strong and significant positive correlation between the ratings of the hemi- and full-faces. These results are consistent with the view that the underpinning of human facial beauty is complex and that bilateral symmetry does not constitute a principle factor in beauty assessment. We discuss that the highly evolved human brain, compared to other animals, as well as symbolic and abstract cognition in humans enable a wide variety of aesthetic reactions.
Type I IFN Signaling Constrains IL-17A/F Secretion by γδ T Cells during Bacterial Infections
Authors: Henry Thomas , Kirimanjeswara Girish S. , Ruby Thomas , Jones Jonathan W. , Peng Kaitian , Perret Magali , Ho Lena , Sauer John-Demian , Iwakura Yoichiro , Metzger Dennis W. , Monack Denise M.
Published: February 2010

Recognition of intracellular bacteria by macrophages leads to secretion of type I IFNs. However, the role of type I IFN during bacterial infection is still poorly understood. Francisella tularensis, the causative agent of tularemia, is a pathogenic bacterium that replicates in the cytosol of macrophages leading to secretion of type I IFN. In this study, we investigated the role of type I IFNs in a mouse model of tularemia. Mice deficient for type I IFN receptor (IFNAR1−/−) are more resistant to intradermal infection with F. tularensis subspecies novicida (F. novicida). Increased resistance to infection was associated with a specific increase in IL-17A/F and a corresponding expansion of an IL-17A+ γδ T cell population, indicating that type I IFNs negatively regulate the number of IL-17A+ γδ T cells during infection. Furthermore, IL-17A–deficient mice contained fewer neutrophils compared with wild-type mice during infection, indicating that IL-17A contributes to neutrophil expansion during F. novicida infection. Accordingly, an increase in IL-17A in IFNAR1−/− mice correlated with an increase in splenic neutrophil numbers. Similar results were obtained in a mouse model of pneumonic tularemia using the highly virulent F. tularensis subspecies tularensis SchuS4 strain and in a mouse model of systemic Listeria monocytogenes infection. Our results indicate that the type I IFN-mediated negative regulation of IL-17A+ γδ T cell expansion is conserved during bacterial infections. We propose that this newly described activity of type I IFN signaling might participate in the resistance of the IFNAR1−/− mice to infection with F. novicida and other intracellular bacteria.
Correlation Study of Pulmonary Embolism and High‐density Lipoprotein Cholesterol
Authors: Wang YuPeng , Wang Ping , Li HongWei
Published: February 2010

Background

It is currently thought that pulmonary embolism and deep vein thrombosis are different manifestations of the same pathological process of venous thromboembolism. Venous thromboembolism has a negative correlation with high‐density lipoprotein cholesterol.

Hypothesis

Pulmonary embolism has a negative correlation with the level of high‐density lipoprotein cholesterol.

Methods

A total of 90 patients with pulmonary embolism, diagnosed and treated at a single center, were retrospectively analyzed for the present study. Among them were 57 cases of pulmonary arterial trunk embolism in group A and 33 cases of pulmonary arterial non‐trunk embolism in group B.

Results

The results showed that the level of high‐density lipoprotein cholesterol decreased markedly in patients with pulmonary arterial trunk embolism as compared to those with pulmonary arterial non‐trunk embolism. A stepwise logistic regression analysis was performed upon the relationship between pulmonary arterial trunk embolism and multiple factors. The results showed that a pulmonary arterial trunk embolism had a negative correlation with the level of high‐density lipoprotein cholesterol and a positive correlation with triglyceride and high sensitivity C‐reactive protein.

Conclusions

Pulmonary arterial trunk embolism is negatively correlated with the level of high‐density lipoprotein cholesterol. Copyright © 2010 Wiley Periodicals, Inc.
Effects of shielding gas compositions on arc plasma and metal transfer in gas metal arc welding
Authors: Rao Z. H. , Liao S. M. , Tsai H. L.
Published: February 2010

This article presents the effects of shielding gas compositions on the transient transport phenomena, including the distributions of temperature, flow velocity, current density, and electromagnetic force in the arc and the metal, and arc pressure in gas metal arc welding of mild steel at a constant current input. The shielding gas considered includes pure argon, 75% Ar, 50% Ar, and 25% Ar with the balance of helium. It is found that the shielding gas composition has significant influences on the arc characteristics; droplet formation, detachment, transfer, and impingement onto the workpiece; and weld pool dynamics and weld bead profile. As helium increases in the shielding gas, the droplet size increases but the droplet detachment frequency decreases. For helium-rich gases, the current converges at the workpiece with a “ring” shape which produces non-Gaussian-like distributions of arc pressure and temperature along the workpiece surface. Detailed explanations to the physics of the very complex but interesting transport phenomena are given.
Memory, symbolic conflict and changes in the national calendar in the Italian Second Republic
Authors: Cossu Andrea
Published: February 2010

Italy's national calendar has undergone a marked transformation in the last 10 years, with the inclusion of new holidays and the assignment of new meanings and celebratory practices to the old ones. This article analyses these changes by focusing on the recent debates about a shared past, involving state leaders as well as intellectuals. After an analysis of the forms of symbolic conflict concerning memory and the relevance of cultural constraints in shaping this conflict, and a brief assessment of the new form of the Republic's calendar, the article examines three major days that deal with the State's treatment of the past: 25 April (Liberation Day); 2 June, seen as the birthday of the Republic; and the recently introduced national Remembrance Day (10 February), which remembers thefoibeor killings and emigration of Italian people on Italy's eastern frontier with former Yugoslavia. The article concludes by identifying the major trends in the public management of memory in the context of Italy's Second Republic.
Stalin and the dove: Left pacifist language and choices of expression between the Popular Front and the Korean War (1948–1953)
Authors: Mariuzzo Andrea
Published: February 2010

The success of Italian movements opposing the war in Iraq during the period 2003–2005 has awakened historians’ interest in the historical features of left-wing pacifism in Italy. Some particularly noteworthy contributions have focused on the campaigns orchestrated around 1950 by the Italian Committee of the Partisans of Peace (the international movement financed and supported by the USSR and international communism against Western anti-Soviet rearmaments). After describing the principal features of existing research, this article focuses on the lexical and communicative aspect characterising left-wing pacifism in Italy in the years immediately following the Atlantic Treaty. It highlights the way in which communist and socialist language gravitated towards the classist and anti-capitalist definitions of ‘war’ and ‘peace’, in line with the position developed in Lenin's reflections in Imperialism, the highest stage of capitalism. However, in the same context, there were images and symbolic references imbued with a rebuttal of the violence of war but with fewer ideological connotations, which reflected an attempt to attract the interest and support of groups and individuals ideologically distant from Marxism. This interweaving of choices of expression contributed to the deep-rooted influence of left-wing pacifism within Italian cultural politics.