bluuebunny/crossref_metadata_2025 huggingface dataset:
Goals as Reference Points: Empirical Evidence from a Virtual Reward System
Authors: von Rechenberg Tobias , Gutt Dominik , Kundisch Dennis
Published: May 2016

Heath et al. [Heath C, Larrick RP, Wu G (1999) Goals as reference points. Cognitive Psych. 38(1):79–109] propose a prospect theory model for goal behavior. Their analytical model is based on the assumption that goals inherit the main properties of the prospect theory value function, i.e., reference point dependence, loss aversion, and diminishing sensitivity. We investigate whether these main properties transfer to goal behavior in the field. We take user activity data from a gamified question and answer (Q&A) community and analyze how users adjust their contribution behavior in the days surrounding goal achievement, where goals are represented by badges. We find that users gradually increase their performance in the days prior to earning a badge, with performance peaking on the day of the promotion. In subsequent days, user performance gradually diminishes again, with the decline being strongest on the day immediately following the badge achievement. These findings reflect the characteristic S-shape of the prospect theory value function which is convex below the reference point and concave above it. Employing the target-based approach, we can interpret the value function as a cumulative density function of a unimodal probability distribution. Our results suggest that it is more likely that active members of the community focus on the next badge relative to the status already achieved, as their next goal and are less likely to focus on more remote (higher-ranked) badges. Our results thus support the transferability of the main properties of the prospect theory value function to goal behavior in the field and suggest a distinct shape of the value function around goals.
A Comparison of Drug Shortages in the Hospital Setting in the United States and Saudi Arabia: An Exploratory Analysis
Authors: Alsheikh Mona , Seoane-Vazquez Enrique , Rittenhouse Brian , Fox Erin R. , Fanikos John
Published: May 2016

Background

Drug shortages are a problem that has been growing in recent years. This problem has an impact on patient outcomes and public health. Most countries have been affected by a diversity of drug supply chain problems.

Objective

To assess explanations for differences in drug shortages reported in the hospital setting in Saudi Arabia (SA) and the United States (US).

Methods

Data were collected in May-June 2014 from Brigham and Women's Hospital (BWH) and from 2 Saudi hospitals: King Abdulaziz University Hospital (KAUH) and King Faisal Specialist Hospital and Research Centre (KFSHRC). Drugs were classified using the World Health Organization (WHO) Anatomical Therapeutic Chemical (ATC) classification system. The drug shortages among the hospitals were compared using descriptive statistics and a chi-square test.

Results

The percentage of the total number of active ingredients reported in shortage was higher in the US hospital setting (15.1%) than in the Saudi hospitals (10.3%) ( p < .0001). KAUH reported the highest number of shortages ( n = 133), followed by BWH ( n = 42) and KFSHRC ( n = 27). A significantly higher percentage of shortages involved injectable drugs in the US hospital setting (78.1%) than the Saudi hospitals (34.43%) ( p ≤ .0001). Nervous system (17%) and alimentary tract and metabolism agents (15.7%) were the therapeutic areas with the higher number of reported shortages in the US and SA hospital settings, respectively.

Conclusions

The number and characteristics of shortages varied by country and hospital. Several factors, including differences in hospital characteristics, number and type of drugs available, and procurement systems, may explain differences in reported shortages.
Utilization of Pharmacy Technicians to Increase the Accuracy of Patient Medication Histories Obtained in the Emergency Department
Authors: Rubin Ellen C. , Pisupati Radhika , Nerenberg Steven F.
Published: May 2016

Purpose

The purpose of this study is to determine the accuracy of a pharmacy technician–collected medication history pilot program in the emergency department. This was completed by reviewing all elements of the technician activity by direct observation and by verifying the technician-collected medication list through a second phone call by a pharmacist to the outpatient pharmacy.

Methods

This was a retrospective, single-center study conducted from March to April 2015. Four certified pharmacy technicians were trained by a postgraduate year 1 (PGY1) pharmacy practice resident on how to collect, verify, and accurately enter medication histories into the electronic medical record. Accuracy of pharmacy technician–collected medication histories was verified by a pharmacist through observation of their patient interviews, review of technician-completed medication history forms, and by contacting the patient's outpatient pharmacy.

Results

The pharmacy technician–completed medication histories resulted in an absolute risk reduction of errors of 50% and a relative risk reduction of errors of 77% ( p < .001) in comparison to medication histories collected by non-pharmacy personnel.

Conclusion

With high accuracy rates, pharmacy technicians proved to be a valuable asset to the medication history process and can enhance patient safety during care transitions. The results of this study further support the Pharmacy Practice Model Initiative vision to advance the pharmacy technician role to improve the process of medication history taking and reconciliation within the health care system.
Personal narrative journalism and podcasting
Authors: Lindgren Mia
Published: May 2016

In her book Speaking Personally (2013), Rosalind Coward maps the rise of a new cultural form – confessional storytelling in journalism. She refers to this first-person writing as perhaps the ‘biggest growth area of journalism’ (12). Interviewees and journalists alike are sharing their real-life experiences, especially suited for the more intimate and personal environments of online media. These personal stories often deal with topics that might appear trivial and domestic, and ‘the inner emotional life, the opposite of subjects considered proper journalism’ (2013: 8). This is an area that has so far received limited critical attention. This article investigates the rise of personal audio narratives in the context of podcasting. It argues that the movement towards personal narratives is intrinsically linked to the intimate nature of the audio medium. Nowhere is this trend more obvious than in recent podcast developments, where US podcasts lead the way with personal and subjective approaches to storytelling. The rapid growth of this storytelling style is escalated by recent experimentation in form and genre, afforded by podcasting, liberated from broadcast conventions and schedules. This article builds on Coward’s study of print journalism and extends it to audio forms in those podcasts. It identifies through a critical analysis of three US podcasts an emerging genre of personal narrative journalism in podcasting.
How podcasting is changing the audio storytelling genre
Authors: McHugh Siobhán
Published: May 2016

This article explores the impact of the post-2014 podcast resurgence on non-fictional audio storytelling formats. The empirical study comprises themed commentary by five significant US, European and Australian editors who commission and produce audio documentaries and features for broadcast and/or podcast. The article provides insights into the changing role played by public broadcasters, the growth of independent podcast networks and the perceived differences between radio and podcasting as a mode of delivering and receiving audio content. Of particular significance is the belief of senior commissioning editors that podcasting is fomenting a new, more informal, genre of audio narrative feature centred on a strong relationship between host and listener, with content that is ‘talkier’ and less crafted. The US audio storytelling podcast sector is growing fast, and much of it has links to a public media ethos, but how to resource it without compromising its editorial independence remains unresolved.
Podcasting: Considering the evolution of the medium and its association with the word ‘radio’
Authors: Berry Richard
Published: May 2016

When evaluating any new medium or technology we often turn to the familiar as a point of reference. Podcasting was no different, drawing obvious comparisons with radio. While there are traits within all podcasts that are radiogenic, one must also consider whether such distinctions are beneficial to the medium. Indeed, one might argue that when one considers the manner in which podcasts are created and consumed then there is an increasing sense in which podcasting can present itself as a distinct medium. While it is true to suggest that as an adaptable medium radio has simply evolved and podcasting is its latest iteration. In doing so, we might fail to appreciate the unique values that exist. In this article, I suggest that by considering podcasts on their terms we might begin to uncover new truths about a medium in change.
Excitability and Burst Generation of AVPV Kisspeptin Neurons Are Regulated by the Estrous Cycle Via Multiple Conductances Modulated by Estradiol Action
Authors: Wang Luhong , DeFazio Richard A. , Moenter Suzanne M.
Published: May 2016

The preovulatory secretory surge of gonadotropin-releasing hormone (GnRH) is crucial for fertility and is regulated by a switch of estradiol feedback action from negative to positive. GnRH neurons likely receive estradiol feedback signals via ERα-expressing afferents. Kisspeptin neurons in anteroventral periventricular nucleus (AVPV) are thought to be critical for estradiol-positive feedback induction of the GnRH surge. We examined the electrophysiological properties of GFP-identified AVPV kisspeptin neurons in brain slices from mice on the afternoon of diestrus (negative feedback) and proestrus (positive feedback, time of surge). Extracellular recordings revealed increased firing frequency and action potential bursts on proestrus versus diestrus. Whole-cell recordings were used to study the intrinsic mechanisms of bursting. Upon depolarization, AVPV kisspeptin neurons exhibited tonic firing or depolarization-induced bursts (DIB). Both tonic and DIB cells exhibited bursts induced by rebound from hyperpolarization. DIB occurred similarly on both cycle stages, but rebound bursts were observed more often on proestrus. DIB and rebound bursts were both sensitive to Ni2+, suggesting that T-type Ca2+currents (ITs) are involved.ITcurrent density was greater on proestrus versus diestrus. In addition toIT, persistent sodium current (INaP) facilitated rebound bursting. On diestrus, 4-aminopyridine-sensitive potassium currents contributed to reduced rebound bursts in both tonic and DIB cells. Manipulation of specific sex steroids suggests that estradiol induces the changes that enhance AVPV kisspeptin neuron excitability on proestrus. These observations indicate cycle-driven changes in circulating estradiol increased overall action potential generation and burst firing in AVPV kisspeptin neurons on proestrus versus diestrus by regulating multiple intrinsic currents.
Electronic Health Records: Then, Now, and in the Future
Authors: Evans R. S.
Published: May 2016

Objectives: Describe the state of Electronic Health Records (EHRs) in 1992 and their evolution by 2015 and where EHRs are expected to be in 25 years. Further to discuss the expectations for EHRs in 1992 and explore which of them were realized and what events accelerated or disrupted/derailed how EHRs evolved. Methods: Literature search based on “Electronic Health Record”, “Medical Record”, and “Medical Chart” using Medline, Google, Wikipedia Medical, and Cochrane Libraries resulted in an initial review of 2,356 abstracts and other information in papers and books. Additional papers and books were identified through the review of references cited in the initial review.

Results: By 1992, hardware had become more affordable, powerful, and compact and the use of personal computers, local area networks, and the Internet provided faster and easier access to medical information. EHRs were initially developed and used at academic medical facilities but since most have been replaced by large vendor EHRs. While EHR use has increased and clinicians are being prepared to practice in an EHR-mediated world, technical issues have been overshadowed by procedural, professional, social, political, and especially ethical issues as well as the need for compliance with standards and information security. There have been enormous advancements that have taken place, but many of the early expectations for EHRs have not been realized and current EHRs still do not meet the needs of today’s rapidly changing healthcare environment.

Conclusion: The current use of EHRs initiated by new technology would have been hard to foresee. Current and new EHR technology will help to provide international standards for interoperable applications that use health, social, economic, behavioral, and environmental data to communicate, interpret, and act intelligently upon complex healthcare information to foster precision medicine and a learning health system.
The ecology of methane in streams and rivers: patterns, controls, and global significance
Authors: Stanley Emily H. , Casson Nora J. , Christel Samuel T. , Crawford John T. , Loken Luke C. , Oliver Samantha K.
Published: May 2016

Streams and rivers can substantially modify organic carbon (OC) inputs from terrestrial landscapes, and much of this processing is the result of microbial respiration. While carbon dioxide (CO2) is the major end‐product of ecosystem respiration, methane (CH4) is also present in many fluvial environments even though methanogenesis typically requires anoxic conditions that may be scarce in these systems. Given recent recognition of the pervasiveness of this greenhouse gas in streams and rivers, we synthesized existing research and data to identify patterns and drivers of CH4, knowledge gaps, and research opportunities. This included examining the history of lotic CH4 research, creating a database of concentrations and fluxes (MethDB) to generate a global‐scale estimate of fluvial CH4 efflux, and developing a conceptual framework and using this framework to consider how human activities may modify fluvial CH4 dynamics. Current understanding of CH4 in streams and rivers has been strongly influenced by goals of understanding OC processing and quantifying the contribution of CH4 to ecosystem C fluxes. Less effort has been directed towards investigating processes that dictate in situ CH4 production and loss. CH4 makes a meager contribution to watershed or landscape C budgets, but streams and rivers are often significant CH4 sources to the atmosphere across these same spatial extents. Most fluvial systems are supersaturated with CH4 and we estimate an annual global emission of 26.8 Tg CH4, equivalent to ~15‐40% of wetland and lake effluxes, respectively. Less clear is the role of CH4 oxidation, methanogenesis, and total anaerobic respiration to whole ecosystem production and respiration. Controls on CH4 generation and persistence can be viewed in terms of proximate controls that influence methanogenesis (organic matter, temperature, alternative electron acceptors, nutrients) and distal geomorphic and hydrologic drivers. Multiple controls combined with its extreme redox status and low solubility result in high spatial and temporal variance of CH4 in fluvial environments, which presents a substantial challenge for understanding its larger‐scale dynamics. Further understanding of CH4 production and consumption, anaerobic metabolism, and ecosystem energetics in streams and rivers can be achieved through more directed studies and comparison with knowledge from terrestrial, wetland, and aquatic disciplines.
A general parameterized mathematical food web model that predicts a stable green world in the terrestrial ecosystem
Authors: Konno Kotaro
Published: May 2016

Terrestrial ecosystems are generally green with vegetation and only a small part (<10%) of the total plant matter is consumed by herbivores annually, which means herbivore density is consistently low and stable. Nonetheless, the mechanism underlying this pattern has been unclear without suitable food web models for predicting the absolute density of the herbivore biomass in physical units. Here, I present a parameterized mathematical food web model describing three‐trophic‐level systems that can predict the biomass density of herbivores h (kg protein/m3) and carnivores c from factors such as nutritive values of plants (np, kg protein/m3), herbivores (nh), and carnivores (nc), searching efficiency (volume) of carnivores (S, m3·m−3·d−1 = d−1), eating efficiency (speed) of herbivores (eh) and carnivores (ec; m3·m−3·d−1 = d−1), respiratory decreases in biomasses (dh and dc, kg·kg−1·d−1 = d−1), absorption efficiencies αh and αc (ratios), and probabilities of carnivores preying on herbivores or carnivores, Phc and Pcc (ratios). The model predicts a stable equilibrium with low herbivore biomass h sufficient to keep the world green provided the food web consists of the three trophic levels, plants, herbivores, and carnivores; intraguild predation exists but is rarer than interguild predation (Phc > Pcc > 0); plants are less nutritive than animals (np < nh, nc); and carnivore searches huge volume daily while eating speed of herbivore is limited (S _ eh). These conditions are well‐realized in aboveground terrestrial ecosystems where plant‐rich “green worlds” are common, vs. animal‐rich belowground and aquatic ecosystems where some conditions are not realized. The h and c calculated from our model agreed well with those from empirical observations in forest ecosystems, where both h and c are within an order of magnitude of 100 mg (fresh biomass/m2 forest), and in savannah ecosystems. The model predicts that plant nutritive value np, digestibility of plants by herbivores αh, and herbivore eating speed eh are positively correlated with h and the intensity of herbivory, which theoretically explains the outdoor defensive effects of plant anti‐nutritive or quantitative defenses (e.g., tannins, protease inhibitors), and predicts that c and the carnivore/herbivore ratio c/h are positively correlated with the relative growth rate of herbivores Gh. The present model introduced parameterized realities into food web theory that previous models lack.
Homoclinic and Heteroclinic Motions in Economic Models with Exogenous Shocks
Authors: Akhmet Marat , Onur Fen Mehmet
Published: May 2016

In this study, we theoretically prove the presence of homoclinic and heteroclinic motions in the dynamics of economic models perturbed with exogenous shocks. An illustrative example based on the Kaldor model of the aggregate economy is presented.
Accuracy Problems of Numerical Calculation of Fractional Order Derivatives and Integrals Applying the Riemann-Liouville/Caputo Formulas
Authors: Brzeziński Dariusz W.
Published: May 2016

In the paper there are presented and evaluated for effectiveness three methods of accuracy increase of fractional order derivatives and integrals computations for application with the Riemann-Liouville/Caputo formulas. They are based on the ideas of either transforming difficult integrand in the formulas to high-accuracy computations requirements of a applied method of numerical integration or adapting a numerical method of integration to handle with high-accuracy a difficult feature in the integrand. Additional accuracy gain is obtained by incorporating increased precision into computations. The actual accuracy improvement by applying presented methods is compared with the capabilities of wide range of available methods of integration.
A model for the operations to render epidemic-free a hog farm infected by the Aujeszky
disease
Authors: Costamagna A. , Drigo M. , Martini M. , Sona B. , Venturino E.
Published: May 2016

We present here a case study for modelling the control of the Aujeszky disease, in a farm declared virus-free. The model is validated on the available data. Simulations are performed to assess different containment strategies for the epidemic. Final recommendations indicate that a strict reduction of biohazards in the farrowing unit should be enforced. Also neglecting the third inoculation in the vaccination protocol leads to a sensible and quantifiable increase of the prevalence of the disease. The findings indicate that it is more important to keep biosafety at a high level in the farrowing unit rather than strive for the highest standards in the gestation unit. Also the importance of a properly implemented vaccination appears fundamental, and its absence can be quantified via our simulations.
Computing Eccentric Version of Second Zagreb Index of Polycyclic Aromatic Hydrocarbons (PAHk)
Authors: Jamil Muhammad Kamran , Farahani Mohammad Reza , Imran Muhammad , Ali Malik Mehar
Published: May 2016

A Recently, Ghorbani et. al. introduced the eccentric versions of first and second Zagreb indices called third and fourth Zagreb indices defined asM
3 (G) = Σ
uv∊E
(G) (ε (u) + ε (ν)) and M
4 (G) = Σ
ν∊V(G)
ε (ν)2, respectively, where ε (ν)is the eccentricity of the vertex ν. In this paper, we compute the closed formula for third Zagreb index of Polycyclic Aromatic Hydrocarbons (PAH
k
).
On the classical and nonclassical symmetries of a generalized Gardner equation
Authors: de la Rosa R. , Bruzón M.S.
Published: May 2016

In this paper, we consider a generalized Gardner equation from the point of view of classical and nonclassical symmetries in partial differential equations. We perform a complete analysis of the symmetry reductions by using the similarity variables and the similarity solutions which allow us to reduce our equation into an ordinary differential equation. Moreover, we prove that the nonclassical method applied to the equation leads to new symmetries, which cannot be obtained by using the Lie classical method. Finally, we calculate exact travelling wave solutions of the equation by using the simplest equation method.
Academic Dysfunction After a Concussion Among US High School and College Students
Authors: Wasserman Erin B. , Bazarian Jeffrey J. , Mapstone Mark , Block Robert , van Wijngaarden Edwin
Published: May 2016

Objectives. To determine whether concussed students experience greater academic dysfunction than students who sustain other injuries.

Methods. We conducted a prospective cohort study from September 2013 through January 2015 involving high school and college students who visited 3 emergency departments in the Rochester, New York, area. Using telephone surveys, we compared self-reported academic dysfunction between 70 students with concussions and a comparison group of 108 students with extremity injuries at 1 week and 1 month after injury.

Results. At 1 week after injury, academic dysfunction scores were approximately 16 points higher (b = 16.20; 95% confidence interval = 6.39, 26.00) on a 174-point scale in the concussed group than in the extremity injury group. Although there were no differences overall at 1-month after injury, female students in the concussion group and those with a history of 2 or more prior concussions were more likely to report academic dysfunction.

Conclusions. Our results showed academic dysfunction among concussed students, especially female students and those with multiple prior concussions, 1 week after their injury. Such effects appeared to largely resolve after 1 month. Our findings support the need for academic adjustments for concussed students.
From Design to Dissemination: Implementing Community-Based Participatory Research in Postdisaster Communities
Authors: Lichtveld Maureen , Kennedy Suzanne , Krouse Rebecca Z. , Grimsley Faye , El-Dahr Jane , Bordelon Keith , Sterling Yvonne , White LuAnn , Barlow Natasha , DeGruy Shannon , Paul Dorothy , Denham Stacey , Hayes Claire , Sanders Margaret , Mvula Mosanda M. , Thornton Eleanor , Chulada Patricia , Mitchell Herman , Martin William J. , Stephens Kevin U. , Cohn Richard D.
Published: May 2016

Objectives. To review how disasters introduce unique challenges to conducting population-based research and community-based participatory research (CBPR).

Methods. From 2007–2009, we conducted the Head-off Environmental Asthma in Louisiana (HEAL) Study in the aftermath of Hurricane Katrina in a Gulf Coast community facing an unprecedented triple burden: Katrina’s and other disasters’ impact on the environment and health, historic health disparities, and persistent environmental health threats.

Results. The unique triple burden influenced every research component; still, most existing CBPR principles were applicable, even though full adherence was not always feasible and additional tailored principles govern postdisaster settings.

Conclusions. Even in the most challenging postdisaster conditions, CBPR can be successfully designed, implemented, and disseminated while adhering to scientific rigor.
Calorie Underestimation When Buying High-Calorie Beverages in Fast-Food Contexts
Authors: Franckle Rebecca L. , Block Jason P. , Roberto Christina A.
Published: May 2016

We asked 1877 adults and 1178 adolescents visiting 89 fast-food restaurants in New England in 2010 and 2011 to estimate calories purchased. Calorie underestimation was greater among those purchasing a high-calorie beverage than among those who did not (adults: 324 ±698 vs 102 ±591 calories; adolescents: 360 ±602 vs 198 ±509 calories). This difference remained significant for adults but not adolescents after adjusting for total calories purchased. Purchasing high-calorie beverages may uniquely contribute to calorie underestimation among adults.
Solubility of n-Butane in Athabasca Bitumen and Saturated Densities and Viscosities at Temperatures Up to 200°C
Authors: Nourozieh Hossein , Kariznovi Mohammad , Abedi Jalal
Published: May 2016

The steam- and/or solvent-based recovery processes are efficient methods for recovery of heavy and extraheavy oils. The performance of these techniques depends on the amount of solvent dissolved in the oil and the variation of oil viscosity with temperature. Thus, full understanding of the quantitative effects of the solvent on heavy-oil viscosity and phase behavior is crucial for feasibility studies, design, and prediction of field-scale processes. Phase-behavior study of bitumen diluted with heavy hydrocarbon solvents, such as butane and pentane, has gained less attention in recent years. These solvents, as good candidates for recently developed recovery methods such as expanding solvent steam-assisted gravity drainage (ES-SAGD), could provide promising oil-production rates.

Thus, the aim of this research is the development of an understanding of the phase behavior of n-butane/Athabasca-bitumen mixtures. It includes both experimental and modeling studies of solubilities and saturated liquid densities and viscosities over wide ranges of temperatures (up to 200 °C) and pressures (up to 8 MPa). Experimental results indicate that the dissolved n-butane in bitumen leads to a significant oil-viscosity reduction, and the effect is more pronounced at lower temperatures and/or higher pressures. The modeling results show that the measured solubilities are adequately represented by the Peng-Robinson equation of state (EOS) with an average absolute relative deviation (AARD) of 9.7%. The saturated liquid densities are also correlated with both the EOS and the effective liquid-density approach with 0.86 and 0.55% AARDs, respectively. The viscosity data are reasonably matched with Pedersen corresponding state.
Residence Time Effect on Iron Perturbation of Taranakite Formation
Authors: Liu C. , Huang P. M. , Zhou J. M.
Published: May 2016

Taranakite is an important reaction product in the immediate vicinity of phosphate fertilizer bands. The residence time effect on taranakite formation at pH 4.0 and on the iron perturbation of its formation at a Fe(II)/Al molar ratio of 1.2 ( and ) was investigated in this study. The crystallization of NH4‐taranakite involved a phase transformation from irregularly shaped x‐ray noncrystalline materials to taranakite. The incorporation of NH+4 ions into taranakite structure was a relatively slow process. The presence of Fe(II) in the solution of the reaction system perturbed the incorporation of NH+4 ions into taranakite structure, especially in the early aging period. Furthermore, the coating or coprecipitation of x‐ray noncrystalline iron phosphates with aluminum phosphates appeared to reduce the dissolution of aluminum phosphates, thus, affecting the phase transformation to taranakite. The presence of Fe(II) greatly decreased the rate of taranakite formation and retarded its formation. This is attributed to iron phosphate coatings as impurities on taranakite particles and the subsequent retardation of its crystal growth by interfering the integration of growth units. The impact of the residence time of Fe perturbation of the formation of taranakite in the immediate vicinity of fertilizer zones in soils, especially under reduced conditions, on the transformation and dynamics of P and N in the terrestrial system merits close attention.
Anionic Polyacrylamide Polymers Effect on Rheological Behavior of Sodium‐Montmorillonite Suspensions
Authors: Heller Hadar , Keren R.
Published: May 2016

Polyacrylamide (PAM) is a long‐chain synthetic polymer that acts as a strengthening agent, binding clay particles together. The interaction between anionic PAM and clay particles is not well understood yet. This interaction was evaluated by rheological measurements for Na‐montmorillonite suspensions. Three anionic PAMs of three molecular weights (MWs) (3.5 × 103, 2 × 105, and 8 × 106 g mol −1) at similar hydrolysis levels (>85%) and three anionic PAMs at various degrees of hydorlysis (DH) (15, 33, and 92%) of similar MW were studied. In an electrolyte‐free clay suspension at DH >85%, only the polymers with high MWs (2 × 105, and 8 × 106) could form a three‐dimensional structure of clay platelets. The smallest polymer molecule size (3.5 × 103) was too short for bonding two adjacent platelets. At similar MW, the effect of the polymers increased with DH. At NaCl concentration of 10 mmolc L−1, at which the attractive forces between clay platelets were weak, the polymers had a significant impact on flow behavior. The effectiveness of the polymers increased with increasing MW and DH. At NaCl concentration of 100 mmolc L−1, the three polymers of DH > 85% stabilized flocs that already existed in the clay suspension. The effectiveness of the polymers in bridging adjacent clay flocs increased as their DH decreased. The polymer conformation factor has a greater impact on clay structure stabilization in suspension than the electrostatic repulsion effect. The clay structure stability was increased with increasing polymer electrostatic negative charge for similar molecular weights.
Microdrip Irrigation of Field Crops
Authors: Assouline S. , Cohen S. , Meerbach D. , Harodi T. , Rosner M.
Published: May 2016

Microdrip irrigation supplies water at a rate close to that of plant water uptake. It is thus expected to improve yields and reduce water losses from drainage below the root zone. To test this assumption, four drip irrigation treatments were applied on corn (Zea mays L.) at Bet Dagan, Israel: (i) daily irrigation with 2 L h−1 emitters (2‐D); (ii) twice‐weekly irrigation with 2 L h−1 emitters (2‐TW); (iii) weekly irrigation with 2 L h−1 emitters (2‐W); (iv) daily microdrip irrigation with 0.25 L h−1 emitters (0.25‐D). Total irrigation was similar for all treatments. Soil water content depth distribution was monitored by the neutron scattering method. Total water uptake (sap flow, SF) was measured using the heat pulse method for two consecutive periods of 2 wk. Relative drying of the 0.60‐ to 0.90‐m soil layer was observed only in the microdrip treatment. These might indicate different root structure or water uptake patterns because of the low application rate. Highest estimated drainage fluxes were obtained for the 2‐D treatment and lowest for the 0.25‐D treatment, especially at the end of the growing period. The SF/ETp ratio was the steadiest for the 0.25‐D treatment. The relationship of canopy conductance to vapor pressure difference for 0.25‐D was not different from those of 2‐D and 2‐TW. Lower conductance values were obtained for 2‐W at the end of the irrigation cycle. Daily irrigation led to the highest yield, while weekly irrigation led to the lowest. The results indicate that microdrip irrigation might improve yields and reduce water losses from drainage below the root zone.
Estimating Hydraulic Properties of Soil Aggregate Skins from Sorptivity and Water Retention
Authors: Gerke Horst H. , Köhne J. Maximilian
Published: May 2016

Skins of soil aggregates often consist of clayey or clay‐organic coatings which may affect preferential flow in aggregated soils. The objective was to determine hydraulic properties of samples with intact and removed (cut) skins and interior/skin hydraulic conductivity ratios for estimating mass transfer parameters in dual‐permeability models. Soil aggregates from the Csd‐horizon of a clay‐loam glacial till soil (Stagnic Calcaric Regosol) were analyzed. A tension‐imbibition apparatus was used for measuring water uptake of multiple aggregates at boundary matric potential heads of −1 and −5 cm. Sorptivities were used to calculate mean weighted water diffusivities and final water contents to fit wetting retention functions. Water retention and hydraulic conductivity functions for the skin layer were derived from differences in water contents and hydraulic resistances between intact and cut samples. Water absorption rates were generally smaller for intact than for cut aggregates. The water retention function of cut was shifted towards smaller water contents compared with intact samples. Mean water diffusivity of intact was 4.5 times smaller than that of cut samples. The interior/skin ratio in unsaturated hydraulic conductivity was about 12 in the measured matric potential head range. The ratio was up to 70 near water saturation and dropped below unity for soil water potentials smaller −1000 cm of water. Aggregate skins may be regarded as a separate porous domain whose hydraulic properties may control water transfer between inter‐ and intraaggregate pore domains in structured soils.
Spatial Variability of Grain Cadmium and Soil Characteristics in a Durum Wheat Field
Authors: Wu J. , Norvell W. A. , Hopkins D. G. , Welch R. M.
Published: May 2016

The accumulation of Cd in edible crops is undesirable because of potential risks to human health. Agronomic efforts to lower Cd in foods will be more effective if we understand the extent and causes of spatial variability of Cd in crops in the field. The primary objective of this study was to characterize the spatial variability of grain Cd and eight soil characteristics in a field of durum wheat [Triticum turgidumL. subsp.durum(Desf.) Husn.] in northeastern North Dakota. A rectangular area of about 0.5 ha was selected to provide a range in several soil characteristics that are reported to influence Cd uptake by plants. These included chelate‐extractable Cd, total soil Cd (Cdt), pH, cation‐exchange capacity (CEC), organic C (OC), and soluble Cl, S, and Na. Location data and paired samples of soil and durum grain were collected at 124 sites. Semivariograms showed that the variations of grain Cd and most soil properties were strongly spatially dependent, with range distances that varied from about 30 to 55 m. A spherical model was fitted successfully to variograms for all characteristics. Maps of grain Cd and soil characteristics were generated by interpolating among measured values by block kriging. Visual and statistical comparisons of maps showed that grain Cd was distributed similarly to measures of soil salinity, especially to the logarithm of soil Cl. Locations with somewhat poorly drained soils, which contained elevated Cl, produced grain with much higher Cd. Our results suggest that knowledge of the spatial distribution of soil characteristics, especially salinity, should be helpful in developing or applying agronomic practices to reduce Cd in durum grain.
Dairy Diet Phosphorus Effects on Phosphorus Losses in Runoff from Land‐Applied Manure
Authors: Ebeling Angela M. , Bundy Larry G. , Powell J. Mark , Andraski Todd W.
Published: May 2016

Phosphorus losses from land‐applied manure can contribute to nonpoint source pollution of surface waters. Dietary P forms and levels influence P concentrations in animal manures and may affect P losses from land‐applied manure. The objective of this study was to determine the effects of dairy diet P concentration on P losses in runoff from land‐applied manure. Dairy manures from two dietary P levels were applied (24 May 1999) at 56 wet Mg ha−1 to a silt loam soil, to provide 40 and 108 kg P ha−1, respectively. The high P diet manure was also applied at 21 wet Mg ha−1 (40 kg P ha−1) to provide a P rate equivalent to the low P diet manure. Plots were subjected to simulated rainfall (75 mm h−1) just prior to corn (Zea mays L.) planting in June and again after harvest in October 1999. Runoff was analyzed for dissolved reactive P (DRP), bioavailable P (BAP), total P (TP), and sediment concentration. Natural runoff from the same plots was collected from November 1999 through July 2000 and analyzed for DRP. At equivalent manure rates, DRP concentration in June runoff from the high P diet manure was ≈10 times higher (2.84 vs. 0.30 mg L−1) than the low P diet manure, and four times higher (1.18 vs. 0.30 mg L−1) when applied at equivalent P rates. Phosphorus concentrations in October runoff and November to July natural runoff were lower (0.02 to 1.69 mg L−1), but treatment effects were the same as for the June runoff. These results show that excessive addition of inorganic P to dairy diets increases the potential for P loss in runoff from land‐applied manure, even at the same P application rate. Diet P effects on potential losses in runoff from land‐applied manure should be considered in P‐indexing and nutrient management planning.
Redoximorphic Features as Indicators of Seasonal Saturation, Lowndes County, Georgia
Authors: Jacobs Peter M. , West Larry T. , Shaw Joey N.
Published: May 2016

Redoximorphic features are generally accepted to be reliable indicators of seasonal saturation although little data exist to verify or refine the relationship in southern Georgia. This 2‐yr study used nested piezometers to investigate the relationship between seasonal saturation and redoximorphic features in seven pedons of the middle Coastal Plain near Valdosta, GA. Three clayey pedons including two Plinthic Kandiudults and a Plinthaquic Paleudult were studied along a hillslope transect. Four sandy pedons including a Typic Quartzipsamment, a Grossarenic Kandiudult, a Grossarenic Kandiaquult, and an Ultic Alaquod were studied along an upland and river terrace transect. Results indicate that (i) pedons that experienced a seasonal high water table are endosaturated; (ii) a gray matrix is indicative of seasonal saturation, on average for >50% of the time, although some sandy horizons may be saturated much less; (iii) Fe depletions are associated with saturation an average of 18% of the study period, a value less than commonly reported; (iv) Fe‐concentration features occur in horizons saturated on average for 24% of the time, although some shallow, especially sandy, horizons were never or only briefly saturated during the study period. Upland and backslope soils, especially Kandiudults with plinthite and reticulate mottling, do not show a consistent relationship between saturation and redoximorphic features; these features appear to be relict and more monitoring in a variety of landscape settings is needed to determine the origin and significance of these features.
Temperature Dependence of Water Retention Curves for Wettable and Water‐Repellent Soils
Authors: Bachmann J. , Horton R. , Grant S. A. , van der Ploeg R. R.
Published: May 2016

The capillary pressure (ψ) in unsaturated porous media is known to be a function of temperature (T). Temperature affects the surface tension (σ) of the pore water, but possibly also the angle of contact (γ). Because information on the temperature dependence of γ in porous media is rare, we conducted experiments with three wettable soils and their hydrophobic counterparts. The objectives were (i) to determine the temperature dependence of the water retention curve (WRC) for wettable and water‐repellent soils, (ii) to assess temperature effects on the apparent contact angle γA derived from those WRCs, and (iii) to evaluate two models (Philip‐de Vries and Grant‐Salehzadeh) that describe temperature effects on ψ. Columns packed with natural or hydrophobized soil materials were first water saturated, then drained at 5, 20, and 38°C, and rewetted again to saturation. Capillary pressure and water content, θ, at five depths in the columns were measured continuously. The observations were used to determine the change in γA with T, as well as a parameter β0 that describes the change in ψ with T It was found that the Philip‐de Vries model did not adequately describe the observed relation between ψ and T A mean value for β0 of −457 K was measured, whereas the Philip‐de Vries model predicts a value of −766 K. Our results seem to confirm the Grant‐Salezahdeh model that predicts a temperature effect on γA For the sand and the silt we studied, we found a decrease in γA between 1.0 to 8.5°, when the temperature was increased from 5 to 38°C. Both β0 and γA were only weak functions of θ. Furthermore, it seemed that for the humic soil under study, surfactants, i.e., the dissolution of soil organic matter, may compound the contact angle effect of the soil solids.
The Feasibility of Shallow Time Domain Reflectometry Probes to Describe Solute Transport Through Undisturbed Soil Cores
Authors: Lee Jaehoon , Horton Robert , Jaynes Dan B.
Published: May 2016

Rapid and nondestructive methods for determining solute transport properties are useful in many soil science applications. Recently, a series of field methods and a time domain reflectometry (TDR) method that could estimate some of the mobile‐immobile model (MIM) parameters, immobile water content (θim) and mass exchange coefficient (α), have been reported. The first objective of this study was to determine an additional parameter, dispersion coefficient (Dm), using the TDR method. The three MIM parameters were estimated from the TDR‐measured data, and the estimated parameters were compared with the estimated parameters from the effluent data. The second objective was to determine whether the TDR‐determined parameters from the surface 2‐cm soil layer could be used to predict effluent breakthrough curves (BTC) at the 20‐cm depth. The TDR‐determined parameters were used to calculate effluent BTCs using the CXTFIT computer program. Parameters obtained by curve fitting of the three parameters simultaneously using TDR data were not similar to the parameters obtained from the effluent BTCs. The parameter estimations were improved by fixing one or two independently determined parameter(s) before curve fitting for the remaining unknown parameter(s). The calculated BTCs were similar to the observed BTCs with coefficient of determination (r2) being 0.99 and root mean square error (RMSE) being 0.036. The TDR data obtained from shallow soil layers were successfully used to describe solute transport through undisturbed soil cores.
A modified upward infiltration method for characterizing soil hydraulic properties
Authors: Young M. H. , Karagunduz A. , Šimůnek J. , Pennell K. D.
Published: May 2016

This note describes a modified upward infiltration method (UIM), which combines laboratory experiments and inverse parameter estimation for determining soil hydraulic properties in the wetting direction. The laboratory method used a Mariotte system to impose a constant head boundary condition on the bottom of a soil column, allowing water to be taken up by the soil material under negative pressure head. Tensiometers installed along the column measured the change in soil pressure head before and after wetting front arrival. The HYDRUS‐1D code was used to obtain an optimal set of van Genuchten parameters, using pressure head and cumulative flux data as auxiliary variables in the objective function. Two soil types (a fine sand and a sandy loam) were tested in triplicate in uniformly‐packed soil columns. The results of the uniform column experiments were repeatable, and showed excellent fits between observed and predicted data. Fitted parameters were used in forward simulations to independently predict water flow behavior in layered columns of the same soil material. The forward simulations successfully predicted water flow for sand‐over‐loam and loam‐over‐sand combinations in layered columns. The relative simplicity of the experimental procedure and the availability of appropriate numerical models renders the modified upward infiltration method an alternative for determining wetting hydraulic properties of soils.
Soil Organic Matter Composition in the Subhumid Ethiopian Highlands as Influenced by Deforestation and Agricultural Management
Authors: Solomon D. , Fritzsche F. , Tekalign M. , Lehmann J. , Zech W.
Published: May 2016

Physical fractionation, degradative wet‐chemical analysis and liquid‐state13C nuclear magnetic resonance (NMR) spectroscopy were used to assess the impact of land use changes on the amount and structural composition of soil organic matter (SOM) in bulk soils and size separates in the subhumid highlands of southern Ethiopia. Soil samples (0–10 cm) were collected from natural forest, tea plantations, 25‐yr cultivated fields at Wushwush (Paleudalf),Podocarpus‐dominated natural forest,Cupressusplantations, and 30‐yr cultivated fields at Munesa (Palehumults) sites. Forest clearing and continuous cultivation led to significant depletion (P< 0.05) of total soil organic C (SOC) (55% and 63%) and N (52% and 60%) in the surface soils, respectively. Compared with the cultivated fields, lower proportions of SOC (51 and 27%) and N (49 and 13%) were lost from the tea andCupressusplantations, respectively. The largest depletion occurred from the labile SOM associated with the sand separates concurrent with higher oxidation states of lignin. However, substantial amounts of these organic substrates were also lost from the stable SOM fraction. Particularly, SOM, associated with the silt‐size separates, decreased suggesting that the SOM in silt was quite susceptible to land use changes and represents a moderately labile SOM pool in the soils under study. Solution13C NMR spectra revealed larger proportions of protonated and C‐ and O‐substituted aryl‐C in the silt than in clay‐size separates. In contrast, O‐alkyl‐C structures were more prominent in the clay than in silt‐size separates, coinciding with the lignin distribution obtained by wet‐chemical analysis. Deforestation and subsequent agricultural management not only resulted in SOM depletion but also markedly altered the chemical composition of SOM in the subhumid highland ecosystems.
Uranyl Surface Complexes Formed on Subsurface Media from DOE Facilities
Authors: Bostick Benjamin C. , Fendorf Scott , Barnett Mark O. , Jardine Phillip M. , Brooks Scott C.
Published: May 2016

A mechanistic understanding of U sorption in natural soils and sediments is useful for determining its transport and bioavailability in the environment. X‐ray absorption spectroscopy (XAS) was used to determine the mechanisms by which U(VI) sorbs to three heterogeneous subsurface media reacted under static and dynamic flow conditions. Regardless of the media chosen, ternary surface complexes were the dominant type of sorption complex. Uranyl phosphate complexes were formed in subsurface media from more acidic environments. In contrast, uranyl carbonate ternary surface complexes formed in media from more neutral conditions. The complexes are predominantly inner‐sphere, although some outer‐sphere complexes may also be present, and appear to be on iron (hydr)oxides and possibly aluminosilicates. Additionally, the uranyl phosphate and carbonate complexes are highly disordered, which contributes to their reversible sorption properties.