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This study examines the short-term impacts of land use land cover (LULC) changes as well as climate variability on the water quality of the Cahaba River watershed in Alabama. The Soil and Water Assessment Tool (SWAT), in combination with spatial-temporal analysis were applied for evaluating contributions of dominant LULC patterns on changes in the sediment yields and nutrient loads. Optimised hot spot analysis with LULC change alone showed decreases in sediment yield and nutrient loads in the upper Cahaba watershed where forests and agricultural lands were replaced by urban development. Climate and LULC raised annual sediment yield and phosphorus load by 2.8% and 61% respectively and lowered nitrogen load by 17%. The combined changes in climate and land use posed a stronger impact on water quality in future. The findings of this study will provide useful information for future water and land management in the Cahaba River Basin.

Perineuronal nets (PNNs) are specialized extracellular matrix structures that surround subsets of neurons throughout the central nervous system (CNS). They are made up of chondroitin sulfate proteoglycans (CSPGs), hyaluronan, tenascin-R, and many other link proteins that together make up their rigid and lattice-like structure. Modulation of PNNs can alter synaptic plasticity and thereby affect learning, memory, and cognition. In the present study, we degraded PNNs in the medial prefrontal (mPFC) and posterior parietal (PPC) cortices of Long–Evans rats using the enzyme chondroitinase ABC (ChABC), which cleaves apart CSPGs. We then measured the consequences of PNN degradation on spatial working memory (WM) with a trial-unique, non-matching-to location (TUNL) automated touchscreen task. All rats were trained with a standard 6 sec delay and 20 sec inter-trial interval (ITI) and then tested under four different conditions: a 6 sec delay, a variable 2 or 6 sec delay, a 2 sec delay with a 1 sec ITI (interference condition), and a 20 sec delay. Rats that received mPFC ChABC treatment initially performed TUNL with higher accuracy, more selection trials completed, and fewer correction trials completed compared to controls in the 20 sec delay condition but did not perform differently from controls in any other condition. Rats that received PPC ChABC treatment did not perform significantly differently from controls in any condition. Posthumous immunohistochemistry confirmed an increase in CSPG degradation products (C4S stain) in the mPFC and PPC following ChABC infusions while WFA staining intensity and parvalbumin positive neuron number were decreased following mPFC, but not PPC, ChABC infusions. These findings suggest that PNNs in the mPFC play a subtle role in spatial WM, but PNNs in the PPC do not. Furthermore, it appears that PNNs in the mPFC are involved in adapting to a challenging novel delay, but that they do not play an essential role in spatial WM function.

Atomic layer deposition (ALD) was used to prepare amorphous thin films of Al2O3, Nb2O5, and Ta2O5on both silicon substrates and aluminum blocks. Etch rates in 10 M NH4OH were determined from X-ray reflectometry data collected as a function of time. Amorphous Al2O3thin films were found to have an etch rate of 0.5 nm min–1and an increase in roughness of ∼0.01 nm min–1. Electron microscopy data showed etch pits, consistent with the increase in roughness. Amorphous Nb2O5and Ta2O5films showed no appreciable etching or roughening over the course of a ∼500 h continuous immersion. An Nb2O5-coated aluminum block showed no corrosion after immersion in 10 M NH4OH for over 200 h, suggesting that the coatings were pinhole-free. These results suggest that amorphous ALD thin films of Nb2O5and Ta2O5are candidates as barrier layers for aluminum in caustic environments.

In most urban areas, freight volumes are not explicitly considered in the transportation planning process. This is primarily due to the proprietary nature of freight data, causing any freight data that are released to be highly aggregated. This paper examines a multitiered methodology to utilize freight data from a federally available, highly aggregated source within an urban planning model to accurately model truck transportation. A case study is included that demonstrates the modeling methodology for a medium-sized urban area, complete with international port, and contains validation results of the freight transportation in the area.

The use of local freight data in transportation planning is essential to ensure accuracy in the travel demand modeling process. Although extensive research work has been performed into the collection and use of household travel data for passenger transportation, limited research work has been performed to collect and use local freight travel data. This paper examines a structure developed to collect and summarize local freight data in an urban area to be used in the transportation planning process within a metropolitan planning organization. The paper concludes that the appropriate collection and analysis of freight data can be performed and the output can be used to support transportation planning activities.

This paper presents the application of simulation to determine the inspection resources needed to minimize disruption resulting from increased security inspection of containers at an intermodal terminal. The initial simulation run intentionally started with a large number of resources. Additional simulation runs were made with a continual reduction of inspection resources until entity throughput at the terminal dropped below allowable limits. Simulation Run 9, with six tailgate inspection stations, three intensive inspection stations, and one general purpose inspector, provided the minimum resources that did not disrupt container throughput. This paper includes the description of the conceptual model framework, the simulation model, the experimental design, and simulation results.

Forecasting traffic volumes to support infrastructure decisions is the heart of the travel demand modeling process. The most commonly used methodology for obtaining these forecasted traffic volumes is the four-step process that considers generation, distribution, mode choice, and route assignment of trips. Each step of the process is performed independently, almost always through the use of computer software, to achieve the final traffic volumes. This paper examines the possibility of forecasting traffic volumes by using a multiple linear regression model to perform what is termed direct demand forecasting. The direct demand forecasting model generates traffic volumes for roadways through the development of a functional relationship between roadway characteristics and socioeconomic influences. A direct demand travel forecasting model has been developed and applied, with a small urban area as a case study community. Results are consistent with those obtained from the traditional four-step methodology.

Abstract:Alder plays an important role in the nitrogen (N) economy of boreal forests because of its high capacity for atmospheric N fixation. Range expansion and increased insect and/or pathogen attack are two potential consequences of climate change that may result in significant, albeit opposite, effects on these systems through influences on alder-mediated N inputs. This study contrasted the effects of weekly defoliation at different intensities on growth and N fixation in Alnus tenuifoliaseedlings with recovery of these traits following a single but intensive defoliation event. Weekly removal of 15, 25, or 40% leaf area for 9 weeks reduced total plant weight by 7, 13, and 29%, respectively, and led to progressive increases in leaf weight ratio at the expense of shoot growth. Although maximum photosynthetic rates (Pmax) were similar among treatments between defoliation events, increasing levels of defoliation led to progressive short-term declines in Pmaximmediately following treatments. Plants with 40% leaf removal had N fixation rates (48.3 ± 2.4 μmol N·g-1·h-1) that were 67% less than undefoliated plants (147.6 ± 8.9 μmol N·g-1·h-1), and even the lowest level of leaf removal led to significant reductions in fixation rates relative to controls. In the recovery experiment, N fixation rates in defoliated plants (158.4± 12.1 μmol N·g-1·h-1) were 40% less than control values (264.1± 18.3 μmol N·g-1·h-1) 24 h following defoliation. After 28 d of regrowth, the total biomasses of defoliated and control plants were indistinguishable; however, N fixation rate in defoliated plants (39.2 ± 2.0 μmol N·g-1·h-1) remained 73% less than that of control plants, suggesting a strong competition between symbiont and host sinks for photosynthate.

The main difficulty in forecasting traffic volumes in small urban communities is identifying the amount and destination of the external traffic. Three methods exist for determining the percentage of external traffic destined for the study community (external–internal trips) or through the study community (external–external trips): a comprehensive origin–destination study, a cordon line origin–destination study, and the use of regression equations. This paper examines the possibility of the use of an alternative technique, based on a spatial economic model, to determine the traffic distribution. The project uses an economic model, which includes surrounding community factors, to determine the trip rates for three communities within Alabama and compares the results obtained from this model with the results given by a commonly accepted regression equation and a recently completed cordon line origin–destination study performed by using video surveillance. It is demonstrated that the economic model performs well for the case study cities, and this model is recommended for use in providing estimates that incorporate a community's economic relationship to neighboring towns for traffic forecasting.

Advanced asset management systems have emerged as important tools in the management, maintenance, and procurement of vehicles for transit fleet operators. Effective design and use of an asset management system can increase productivity, enhance public perception, and provide a consistent basis for decision making and planning. This paper documents the design and application of a vehicle procurement model in an asset management system created for the Alabama Department of Transportation to manage vehicles purchased and operated through the Section 5311 federal grant program. The vehicle procurement model predicts future vehicle serviceability, or condition rating, by using a combination of factors, including service area socioeconomic data and vehicle usage data. Application of the system helps transportation professionals estimate the overall fleet quality, identify vehicles that will need to be replaced each year, aid in the management of vehicles, and provide a basis for predicting future funding and budgetary needs.

Abstract:In interior Alaskan boreal forests two species of alder, Alnus tenuifoliaand Alnus crispa, represent keystone species in floodplain and upland landscapes, respectively, due to the ability of these plants to form symbiotic associations with the nitrogen-fixing actinomycete, Frankia.It is believed that as much as 70% of the nitrogen (N) accumulated during the 200-y successional development of these forests is derived through atmospheric fixation by these species. Estimates of gross N inputs in these and many other ecosystems have traditionally utilized the acetylene reduction assay (ARA), which requires a conversion factor of the ratio of acetylene to N2reduced by nitrogenase, the primary enzyme. Despite the fact that small variations in the reduction ratio can substantially influence estimates of N inputs, few studies have investigated how it varies spatially and temporally. The present study sought to 1) determine this conversion factor for both species of alder in situby calibration of the ARA against a 15N2uptake method we developed for field use and 2) determine whether the conversion factor varied with the successional stage in which the alders occurred. Averaged across all plants, the ratio of acetylene to N2reduced was significantly greater in A. crispa.Significant differences in the value of the conversion factor were observed between early succession and later (mid and late) successional sites for both species. Such differences were also observed among replicate sites within and among stages. However, these stage and site differences may also be due to seasonal effects, which could not be controlled for with our design. Specific acetylene reductase activity (SARA) was only correlated with 15N2uptake for early successional sites measured early in the growing season, when N2-fixation rates were lowest and the conversion factor was closest to the theoretical value of 4. A significant negative correlation was found between the conversion factor value and the rate of enzyme activity as determined by the 15N2uptake method. Two hypotheses are proposed to explain this result: 1) that it is due to changes in the kinetic properties of nitrogenase at high levels of enzyme activity, resulting in an increased affinity of the enzyme for N2relative to C2H2, and 2) that the concentration of C2H2used in our ARA was insufficient to saturate nitrogenase.

Transportation engineers and planners attempt to understand urban travel characteristics to develop, formulate, and analyze problems and opportunities better. Transportation professionals use urban transportation models and typically implemented the four-step urban transportation planning process. This study examined a modified planning process that preassigned external trips to the transportation network before distributing and assigning internal trips. The preassignment, or preloading, of external trips helped to ensure that trips passing through the network were assigned to only the major through routes and that internal trips were modeled with the knowledge that external trips were present on the roadways before selecting destination or route. The study concluded that the preload methodology did not affect the validity of a travel model in a medium-sized urban travel forecast model and reduced assignment error on minor arterial roadways, which would not be the typical routes used by external travelers, to a level below the maximum deviation where an incorrect decision would be made regarding improvements to the roadway infrastructure.

Recently, focus on the analysis of public transit systems has been increasing. The Transit Capacity and Quality of Service Manualconsolidates information on current practices. By stating that no national studies support transit capacity analysis for demand-responsive operations, the manual identifies an inability to estimate capacity and level of service for agencies that provide demand-responsive transit. A procedure for calculating a serviceability index (SI) for demand-responsive transit operators based on regional socioeconomic conditions and internal operation data is presented. The methodology results from a survey of several demand-responsive transit providers in Alabama and data analysis. A case study for two counties served by the Northwest Alabama Council of Local Governments transit agency illustrates the SI calculation to identify benefits and drawbacks. Generated with input from transit providers, SI can be used to evaluate and compare demand-responsive transit operation.

Traditional transportation modeling activities in medium-sized urban communities follow the four-step planning process: trip generation, trip distribution, mode split, and traffic assignment. These models forecast daily traffic volumes on major roadways of the communities to support infrastructure investment decisions. Recently, researchers have focused on dynamic traffic-assignment models, which provide time as a measure in the trip-modeling process, to support incident management and intelligent transportation system–based decisions. As a methodology to support the dynamic traffic-assignment models, development of a dynamic trip-generation model for a medium-sized urban community is considered. An overview of the need for dynamic trip-generation data is presented, and a methodology and a data-collection effort to develop a dynamic trip-generation model are discussed. Results are included of a validation study performed on the model. It is concluded that the models developed in the effort can provide dynamic trip-generation data and represent a first step toward making the dynamic transportation model a viable resource.

The geographic information system (GIS) has been demonstrated to be an effective tool for transportation forecasting and scenario analysis. Previous efforts have linked full-function GIS packages with transportation forecasting models. Tools developed to provide a modeling environment more appropriate for the technical knowledge level and budget requirements of small urban or rural areas are described. Specifically, the needs of metropolitan planning organizations and regional planning affiliations in Iowa were considered in the system design. A desktop mapping package, MAPINFO, is integrated with an urban transportation planning model, TRANPLAN, to provide an interface for network analysis. With the system, network modifications and changes representing alternative demand scenarios are made in the GIS environment, and data are exported to the TRANPLAN format, and, after analysis, returned to the GIS for effective presentation of results. User tools were tested and a case study demonstrating alternatives analysis and display capabilities is presented. Although developed and tested for Des Moines, the system can easily be transferred to other agencies to enhance transportation planning capabilities.