Asphalt Cement Containing AC-13, HR-522, Final Report, 1988

Stopping and turning maneuvers on high traffic volume asphalt cement concrete surfaced roads and streets often cause distortion of the pavement. Distortion may show up as excessive rutting in the wheel path, shoving of the pavement and/or rippling of the surface. Often times repeated corrective work such as cold milling or heater planing is required in these areas to maintain the pavement surface in a reasonable condition. In recent years polymer additives have been developed for asphalt cement concrete paving mixes that show promise in improving the inplace stability of the pavements. AC-13 (Styrelf 13) available from Bitucote Products Company, St. Louis, Missouri is an asphalt cement that has been modified by an additive to exhibit characteristics of very high stability in asphalt mixes.

Two-step postmortem angiography with a modified heart-lung machine: preliminary results.

OBJECTIVE: The purpose of this study was to adapt and improve a minimally invasive two-step postmortem angiographic technique for use on human cadavers. Detailed mapping of the entire vascular system is almost impossible with conventional autopsy tools. The technique described should be valuable in the diagnosis of vascular abnormalities. MATERIALS AND METHODS: Postmortem perfusion with an oily liquid is established with a circulation machine. An oily contrast agent is introduced as a bolus injection, and radiographic imaging is performed. In this pilot study, the upper or lower extremities of four human cadavers were perfused. In two cases, the vascular system of a lower extremity was visualized with anterograde perfusion of the arteries. In the other two cases, in which the suspected cause of death was drug intoxication, the veins of an upper extremity were visualized with retrograde perfusion of the venous system. RESULTS: In each case, the vascular system was visualized up to the level of the small supplying and draining vessels. In three of the four cases, vascular abnormalities were found. In one instance, a venous injection mark engendered by the self-administration of drugs was rendered visible by exudation of the contrast agent. In the other two cases, occlusion of the arteries and veins was apparent. CONCLUSION: The method described is readily applicable to human cadavers. After establishment of postmortem perfusion with paraffin oil and injection of the oily contrast agent, the vascular system can be investigated in detail and vascular abnormalities rendered visible.

Occupational research : selected bibliography of Iowa research in vocational-technical education and related areas -- 1960-1967

The Iowa RCU has developed this selected bibliography of Iowa research in Vocational-Technical Education and related areas. Contract research as well as abstracts of masters theses and doctoral dissertations are included. For the most part, these abstracts have been gleaned from research at the three state universities and Drake University.

Occupational research supplement no. 1 : selected bibliography of Iowa research in vocational-technical education and related areas -- 1963-1968

This is a supplement to the selected bibliography of Iowa research in Vocational-Technical Education and related areas that the Iowa RCU developed. Contract research as well as abstracts of masters theses and doctoral dissertations are included.

Occupational research supplement no. 2 : selected bibliography of Iowa research in vocational-technical education and related areas -- 1966-1968

This is supplement no. 2 to the selected bibliography of Iowa research in Vocational-Technical Education and related areas that the Iowa RCU developed. Contract research as well as abstracts of masters theses and doctoral dissertations are included.

Guidelines for Removal of Traffic Control Devices in Rural Areas, TR-527, 2005

It is commonly regarded that the overuse of traffic control devices desensitizes drivers and leads to disrespect, especially for low-volume secondary roads with limited enforcement. The maintenance of traffic signs is also a tort liability concern, exacerbated by unnecessary signs. The Federal Highway Administration’s (FHWA) Manual on Uniform Traffic Control Devices (MUTCD) and the Institute of Transportation Engineer’s (ITE) Traffic Control Devices Handbook provide guidance for the implementation of STOP signs based on expected compliance with right-of-way rules, provision of through traffic flow, context (proximity to other controlled intersections), speed, sight distance, and crash history. The approach(es) to stop is left to engineering judgment and is usually dependent on traffic volume or functional class/continuity of system. Although presently being considered by the National Committee on Traffic Control Devices, traffic volume itself is not given as a criterion for implementation in the MUTCD. STOP signs have been installed at many locations for various reasons which no longer (or perhaps never) met engineering needs. If in fact the presence of STOP signs does not increase safety, removal should be considered. To date, however, no guidance exists for the removal of STOP signs at two-way stop-controlled intersections. The scope of this research is ultra-low-volume (< 150 daily entering vehicles) unpaved intersections in rural agricultural areas of Iowa, where each of the 99 counties may have as many as 300 or more STOP sign pairs. Overall safety performance is examined as a function of a county excessive use factor, developed specifically for this study and based on various volume ranges and terrain as a proxy for sight distance. Four conclusions are supported: (1) there is no statistical difference in the safety performance of ultra-low-volume stop-controlled and uncontrolled intersections for all drivers or for younger and older drivers (although interestingly, older drivers are underrepresented at both types of intersections); (2) compliance with stop control (as indicated by crash performance) does not appear to be affected by the use or excessive use of STOP signs, even when adjusted for volume and a sight distance proxy; (3) crash performance does not appear to be improved by the liberal use of stop control; (4) safety performance of uncontrolled intersections appears to decline relative to stop-controlled intersections above about 150 daily entering vehicles. Subject to adequate sight distance, traffic professionals may wish to consider removal of control below this threshold. The report concludes with a section on methods and legal considerations for safe removal of stop control.

Investigation of Improved Utility Cut Repair Techniques to Reduce Settlement in Repaired Areas, Phase II, TR-566, 2010

Trench maintenance problems are caused by improper backfill placement and construction procedures. This report is part of a multiphase research project that aims to improve long-term performance of utility cut restoration trenches. The goal of this research is to improve pavement patch life and reduce maintenance of the repaired areas. The objectives were to use field-testing data, laboratory-testing data, and long-term monitoring (elevation survey and falling weight deflectometer testing) to suggest and modify recommendations from Phase I and to identify the principles of trench subsurface settlement and load distribution in utility cut restoration areas by using instrumented trenches. The objectives were accomplished by monitoring local agency utility construction from Phase I, constructing and monitoring the recommended trenches from Phase I, and instrumenting trenches to monitor changes in temperature, pressure, moisture content, and settlement as a function of time to determine the influences of seasonal changes on the utility cut performance.

Evaluation of the SHRP Modified Georgia Digital Faultmeter, MLR-93-01, 1993

The SHRP Modified Georgia Digital Faultmeter was loaned to the Iowa Department of Transportation in January 1993 for evaluation. A study was undertaken comparing the faultmeter to Iowa's current method of fault measurement. The following conclusions were made after comparing the faultmeter to Iowa's gauge: The faultmeter was lighter and easier to maneuver and position. The faultmeter's direct readout was quicker to read. The faultmeter has increased precision. The faultmeter gave consistently lower fault readings than the Iowa gauge.

Erosion and channel change as factors of landslides and valley formation in Champlain sea clays: The Chacoura river, Quebec, Canada

The Champlain Sea clays of Eastern Canada are incised by numerous rivers. Their slopes have been modified by landslides: on the Chacoura River near Trois-Rivières (Quebec), several large landslide scars, more or less recent, are visible. The role of erosion (channel incision, lateral channel migration and erosion of slopes due to agricultural drainage) as a trigger of these landslides is important. The aim of this study is to understand how erosion and landslides are related to valley development. From a detailed analysis of aerial photographs and DEMs, a map of the phenomena has been drawn by identifying various elements such as landslides, limits of the slope, position of the channel, and the area covered by forest. It is shown that channel change and erosion are strongly linked to landslides by the fact that they change the bank morphology in an unstable way. A slide in itself is a natural way for the slope to achieve stability. But when it occurs in a stream, it creates a disturbance to the stream flow enhancing local erosion which may change the river path and generate more erosion downstream or upstream resulting in more slides. Cross-valley sections and a longitudinal profile show that landslides are a major factor of valley formation. It appears that the upper part of the Chacoura River valley is still unaffected by landslides and has V-shaped sections. The lower part has been subject to intense erosion and many landslide scars can be seen. This shows that the valley morphology is transient, and that future activity is more likely to occur in the upper part of the river. Therefore the identification of areas prone to erosion will help determine the possible location of future large landslides just like the ones that occurred in the lower part.

Ain't no mountain high enough: plant invasions reaching new elevations

Most studies of invasive species have been in highly modified, lowland environments, with comparatively little attention directed to less disturbed, high-elevation environments. However, increasing evidence indicates that plant invasions do occur in these environments, which often have high conservation value and provide important ecosystem services. Over a thousand non-native species have become established in natural areas at high elevations worldwide, and although many of these are not invasive, some may pose a considerable threat to native mountain ecosystems. Here, we discuss four main drivers that shape plant invasions into high-elevation habitats: (1) the (pre-)adaptation of non-native species to abiotic conditions, (2) natural and anthropogenic disturbances, (3) biotic resistance of the established communities, and (4) propagule pressure. We propose a comprehensive research agenda for tackling the problem of plant invasions into mountain ecosystems, including documentation of mountain invasion patterns at multiple scales, experimental studies, and an assessment of the impacts of non-native species in these systems. The threat posed to high-elevation biodiversity by invasive plant species is likely to increase because of globalization and climate change. However, the higher mountains harbor ecosystems where invasion by non-native species has scarcely begun, and where science and management have the opportunity to respond in time.

Fusion of the extended modified liquid drop model for nucleation and dynamical nucleation theory

We present a new phenomenological approach to nucleation, based on the combination of the extended modified liquid drop model and dynamical nucleation theory. The new model proposes a new cluster definition, which properly includes the effect of fluctuations, and it is consistent both thermodynamically and kinetically. The model is able to predict successfully the free energy of formation of the critical nucleus, using only macroscopic thermodynamic properties. It also accounts for the spinodal and provides excellent agreement with the result of recent simulations.

Use of LIDAR-based Elevation Data for Highway Drainage Analysis: A Qualitative Assessment, 2003

US Geological Survey (USGS) based elevation data are the most commonly used data source for highway hydraulic analysis; however, due to the vertical accuracy of USGS-based elevation data, USGS data may be too “coarse” to adequately describe surface profiles of watershed areas or drainage patterns. Additionally hydraulic design requires delineation of much smaller drainage areas (watersheds) than other hydrologic applications, such as environmental, ecological, and water resource management. This research study investigated whether higher resolution LIDAR based surface models would provide better delineation of watersheds and drainage patterns as compared to surface models created from standard USGS-based elevation data. Differences in runoff values were the metric used to compare the data sets. The two data sets were compared for a pilot study area along the Iowa 1 corridor between Iowa City and Mount Vernon. Given the limited breadth of the analysis corridor, areas of particular emphasis were the location of drainage area boundaries and flow patterns parallel to and intersecting the road cross section. Traditional highway hydrology does not appear to be significantly impacted, or benefited, by the increased terrain detail that LIDAR provided for the study area. In fact, hydrologic outputs, such as streams and watersheds, may be too sensitive to the increased horizontal resolution and/or errors in the data set. However, a true comparison of LIDAR and USGS-based data sets of equal size and encompassing entire drainage areas could not be performed in this study. Differences may also result in areas with much steeper slopes or significant changes in terrain. LIDAR may provide possibly valuable detail in areas of modified terrain, such as roads. Better representations of channel and terrain detail in the vicinity of the roadway may be useful in modeling problem drainage areas and evaluating structural surety during and after significant storm events. Furthermore, LIDAR may be used to verify the intended/expected drainage patterns at newly constructed highways. LIDAR will likely provide the greatest benefit for highway projects in flood plains and areas with relatively flat terrain where slight changes in terrain may have a significant impact on drainage patterns.

Colonization by mites of glacier-free areas in King George Island, Antarctica

This work aimed to investigate the ratio of colonization by terrestrial mites on ice-free areas created by the ongoing climate-induced melting of Antarctic glaciers. Glacier retreat opens new ice-free areas for the colonization by vegetation and animals. The study was undertaken on the Antarctic Specially Protected Area no. 128 (West Coast of the Admiralty Bay, King George Island, South Shetlands Islands). Transects marked between the Ecology, Baranowski and Windy Glaciers, and a sea shore were used to collect soil samples. Oribatid mites were found only on near-shore areas, on patches of vegetation of more than 30 years of age. The colonization by mite communities is strongly determined by the presence of plants.

Composition and functional groups of epiedaphic ants (Hymenoptera: Formicidae) in irrigated agroecosystem and in nonagricultural areas

The objective of this work was to evaluate the species composition and functional groups of ants in nonagricultural (NA) and in irrigated areas (S, seasonal irrigation; P, irrigation with well water; W, irrigation with wastewater) in an arid agricultural region in central Mexico, throughout 2005 and 2006. A total of 52,358 ants belonging to 6 subfamilies, 21 genera and 39 species was collected using pitfall traps. The species best represented in all plots were: Forelius pruinosus, Pheidole obtusospinosa, Monomorium minimum and Dorymyrmex spp. NA plots recorded the highest density of ants. The highest values for diversity (H') and equitativity (J') were recorded in NA and P plots, while the lowest were recorded in W plots. Cluster analysis showed two different groups regarding species composition: NA-S and W-P. Functional groups recorded were: dominant Dolichoderinae, three species; subordinate Camponotini, five species; hot climate specialists, three species; tropical climate specialists, seven species; cold climate specialists, five species; cryptic species, one species; opportunists, six species; generalized Myrmicinae, nine species. Agricultural activity affects the structure of the ant community with epiedaphic forage, and the constant use of irrigation wastewater in conjunction with intense agricultural practices has negative effect upon species richness of epiedaphic ants.