Sponsored by ASABE Galt House

Abstract. Several studies were conducted by Forest Service researchers and University and Industrial collaborators that investigated the potential for lessening soil surface disturbances and compaction in forest operations through modifications of machine components or harvest systems. Specific machine modifications included change in tire size, use of dual tire systems, reduction of tire inflation pressures, reductions in load size and ground pressure. Soil surface disturbances were most evident in sites with high soil moisture content that were lessened by lowering tire inflation pressures or using a dual tire configuration. Traffic intensity increased rutting potential of harvest sites, especially with the use of narrow tires. Traffic intensities varied spatially and in intensity in clear cut harvest operations with intensities that ranged between none to 100 or more. Soil physical properties responded to choice of tire size and inflation pressure with narrower tires and/or higher inflation pressures associated with increased soil compaction. Soil disturbance data collected in three clear cut operations in Alabama indicated no differences among the operations by location, but soil response varied depending on site properties. Soil physical properties did not necessarily reflect the intensity of soil disturbance

Prediction of a Highly Activated State of CO Adsorbed on an Al/Fe(100) Bimetallic

Using periodic slab density functional theory, we investigate CO adsorption, diffusion, and dissociation energetics on a monolayer of Al covering Fe(100) [Al/Fe(100)]. We predict a weakly chemisorbed state of CO to exist on Al/Fe(100), with CO adsorbing on the 4-fold hollow site in a very tilted fashion. This state is predicted to have an extremely low CO stretching frequency of only 883 cm-1, indicating a dramatically weakened CO bond relative to gaseous CO, even though the molecule is predicted to bind to Al/Fe(100) quite weakly. We predict that dissociation of CO starting from this weakly adsorbed state has a barrier of only ∼0.35 eV, which is ∼0.70 eV lower than that on Fe(100). To understand how the underlying substrate changes the electronic properties of the supported Al monolayer, we compare CO adsorption on Al/Fe(100) to its adsorption on analogous pure Al(100) surfaces. This highly activated yet weakly bound state of CO on Al/Fe(100) suggests that Al/Fe(100) could be an effective low-temperature bimetallic catalyst in reducing environments. 1

Measuring Child Health Coverage: Validation of Maternal-Reported Care-seeking and New Methods for Estimating Coverage of Appropriate Management of Childhood Illness

Problem Statement: Accurate data on coverage of health interventions is required for continued reduction in child mortality. This study assessed the validity of the standard indicator on care-seeking for child illness and methods for linking household and provider data to improve measures of child health coverage. Methods: The study was conducted in Southern Province, Zambia. Children <5 years were given cards with barcodes. Healthcare providers tracked sick children brought for care by scanning barcodes and distributing tokens. Provider preparedness to manage child illness was assessed using a tool based on the Service Availability and Readiness Assessment. We conducted a household survey on care-seeking for child illness in the preceding two weeks. We compared maternal-reported and provider-documented care-seeking events. We linked household data on source of care with provider preparedness data to estimate coverage using exact source care and measures of geographic proximity, with data on all providers and only health facilities. Results: Most children sought care from government facilities or community-based agents (CBAs). We found high sensitivity (0.95, 95% CI: 0.88-0.98) and reasonable specificity (0.74, 95% CI: 0.65-0.81) of maternal report of care-seeking for child illness. Coverage of appropriate management of child illness, calculated using a measure based on provider preparedness, was 55% (95% CI: 51%-58%) overall. Exact-match linking was effective at this small scale. Most ecological linking methods produced similar coverage estimates. Use of facility-only data reduced coverage estimates in the rural area because CBAs were a common skilled source of care. Conclusions: Maternal report is a valid measure of source of care for child illness in settings where utilization of public sector providers is high. With reliable household data on source of care, exact-match linking may be a feasible method for producing more informative estimates of coverage of appropriate management of child illness. Ecological linking with data on a sample of all skilled providers may be as effective as exact-match linking in areas with low variation in preparedness within a provider category or minimal provider bypassing. More studies are needed at larger scale and a more diverse provider landscape to further evaluate and guide linking methodology

Small herbaria contribute unique biogeographic records to county, locality, and temporal scales

With digitization and data sharing initiatives underway over the last 15 years, an important need has been prioritizing specimens to digitize. Because duplicate specimens are shared among herbaria in exchange and gift programs, we investigated the extent to which unique biogeographic data are held in small herbaria vs. these data being redundant with those held by larger institutions. We evaluated the unique specimen contributions that small herbaria make to biogeographic understanding at county, locality, and temporal scales

Understanding the apparent fractional charge of protons in the aqueous electrochemical double layer

A detailed atomic-scale description of the electrochemical interface is essential to the understanding of electrochemical energy transformations. In this work, we investigate the charge of solvated protons at the Pt(111) | H_2O and Al(111) | H_2O interfaces. Using semi-local density-functional theory as well as hybrid functionals and embedded correlated wavefunction methods as higher-level benchmarks, we show that the effective charge of a solvated proton in the electrochemical double layer or outer Helmholtz plane at all levels of theory is fractional, when the solvated proton and solvent band edges are aligned correctly with the Fermi level of the metal (E_F). The observed fractional charge in the absence of frontier band misalignment arises from a significant overlap between the proton and the electron density from the metal surface, and results in an energetic difference between protons in bulk solution and those in the outer Helmholtz plane

Soil carbon sequestration and changes in fungal and bacterial biomass following incorporation of forest residues.

Sequestering carbon (C) in forest soils can benefit site fertility and help offset greenhouse gas emissions. However, identifying soil conditions and forest management practices which best promote C accumulation remains a challenging task. We tested whether soil incorporation of masticated woody residues alters short-term C storage at forested sites in western and southeastern USA. Our hypothesis was that woody residues would preferentially stimulate soil fungal biomass, resulting in improved C use efficiency and greater soil C storage. Harvest slash at loblolly pine sites in South Carolina was masticated (chipped) and either (1) retained on the soil surface, (2) tilled to a soil depth of 40 cm, or (3) tilled using at least twice the mass of organics. At comparative sites in California, live woody fuels in ponderosa pine stands were (1) masticated and surface applied, (2) masticated and tilled, or (3) left untreated. Sites with clayey and sandy soils were compared in each region, with residue additions ranging from 20 to 207 Mg ha_1. Total and active fungal biomass were not strongly affected by residue incorporation despite the high input of organics. Limited response was also found for total and active bacterial biomass. As a consequence, fungal:bacterial (F:B) biomass ratios were similar among treatments at each site. Total soil C was elevated at one California site following residue incorporation, yet was significantly lower compared to surface-applied residues at both loblolly pine sites, presumably due to the oxidative effects of tilling on soil organic matter. The findings demonstrated an inconsequential effect of residue incorporation on fungal and bacterial biomass and suggest a limited potential of such practices to enhance long-term soil C storage in these forests

Light and flow regimes regulate the metabolism of rivers

Mean annual temperature and mean annual precipitation drive much of the variation in productivity across Earth's terrestrial ecosystems but do not explain variation in gross primary productivity (GPP) or ecosystem respiration (ER) in flowing waters. We document substantial variation in the magnitude and seasonality of GPP and ER across 222 US rivers. In contrast to their terrestrial counterparts, most river ecosystems respire far more carbon than they fix and have less pronounced and consistent seasonality in their metabolic rates. We find that variation in annual solar energy inputs and stability of flows are the primary drivers of GPP and ER across rivers. A classification schema based on these drivers advances river science and informs management.We thank Ted Stets, Jordan Read, Tom Battin, Sophia Bonjour, Marina Palta, and members of the Duke River Center for their help in developing these ideas. This work was supported by grants from the NSF 1442439 (to E.S.B. and J.W.H.), 1834679 (to R.O.H.), 1442451 (to R.O.H.), 2019528 (to R.O.H. and J.R.B.), 1442140 (to M.C.), 1442451 (to A.M.H.), 1442467 (to E.H.S.), 1442522 (to N.B.G.), 1624807 (to N.B.G.), and US Geological Survey funding for the working group was supported by the John Wesley Power Center for Analysis and Synthesis. Phil Savoy contributed as a postdoc- toral associate at Duke University and as a postdoctoral associate (contractor) at the US Geological Survey

Understanding the apparent fractional charge of protons in the aqueous electrochemical double layer

A detailed atomic-scale description of the electrochemical interface is essential to the understanding of electrochemical energy transformations. In this work, we investigate the charge of solvated protons at the Pt(111) | H_2O and Al(111) | H_2O interfaces. Using semi-local density-functional theory as well as hybrid functionals and embedded correlated wavefunction methods as higher-level benchmarks, we show that the effective charge of a solvated proton in the electrochemical double layer or outer Helmholtz plane at all levels of theory is fractional, when the solvated proton and solvent band edges are aligned correctly with the Fermi level of the metal (E_F). The observed fractional charge in the absence of frontier band misalignment arises from a significant overlap between the proton and the electron density from the metal surface, and results in an energetic difference between protons in bulk solution and those in the outer Helmholtz plane