Skid Resistance of the Secondary Road System in Iowa, MLR-77-1, 1977

The Iowa Department of Transportation has been conducting skid resistance tests on the paved secondary system on a routine basis since 1973. This report summarizes the data obtained through 1976 on 10,101 miles in 95 of the 99 counties in Iowa. A summary of the skid resistance on the secondary system is presented by pavement type and age. The data indicates that the overall skid resistance on this road system is excellent. Higher traffic roads (over 1000 vehicles per day) have a lower skid resistance than the average of the secondary roads for the same age and pavement type. The use of non-polishing aggregates in asphaltic concrete paving surface courses and transverse grooving of portland cement concrete paving on high traffic roads is recommended. The routine resurvey of skid resistance on the secondary road system on a 5-year interval is probably not economically justified and could be extended to a 10-year interval.

A guide to resources for the study of the recent history of the United States in the libraries of the University of Iowa, the State Historical Society of Iowa, and in the Herbert Hoover Presidential Library, 1977

This guide is designed as a finding aid for researchers seeking materials on a particular topic and it indicates the nature and extent of resources for the study of United States history available at the Historical Society of Iowa, the Herbert Hoover Presidential Library and the Iowa University Libraries.

Adaptação de Thyrinteina arnobia em novo hospedeiro e defesa induzida por herbívoros em eucalipto

O sistema de defesa induzido de plantas é ativado quando herbívoros se alimentam das mesmas. Alternativamente, herbívoros podem se adaptar a espécies de plantas filogeneticamente próximas ao seu hospedeiro de origem. O objetivo deste trabalho foi comparar o desenvolvimento de Thyrinteina arnobia em plantas de goiaba (hospedeiro de origem) e de eucalipto (hospedeiro novo) em campo. Adicionalmente, estudou-se a biologia deste inseto em laboratório fornecendo folhas de eucalipto previamente danificadas por lagartas de T. arnobia e folhas sem danos. A sobrevivência larval em eucalipto, 78,00%, foi superior à de goiaba, 29,33%. O ciclo larval foi de 27,90 dias em goiaba e de 30,30 dias em eucalipto. Em testes de laboratório, o ciclo larval em eucalipto limpo, 36,39 dias, foi maior do que em eucalipto danificado, 32,89 dias. A mortalidade larval em eucalipto danificado foi de 30,00% e de 10,00% em eucalipto limpo. Os resultados indicam que a goiaba não é um bom hospedeiro para T. arnobia possivelmente por apresentar um sistema mais efetivo de defesa. Embora o eucalipto possa ser um hospedeiro mais favorável ao desenvolvimento e estabelecimento do inseto, pode também reduzir populações do herbívoro ativando o seu sistema de defesa induzido.

Geohydrology of Muscatine Island, Muscatine County, Iowa, 1977

The availability of large quantities of high-quality ground water from the Muscatine Island aquifer has had a tremendous impact upon urban, industrial and agricultural development of this part of Iowa. Although the nonpumping level of water has been lowered significantly near major pumping centers through time, proper management of this water resource can assure a continued supply of water for all competing users. This report provides basic information for long range management. Fold out maps are included.

Detection of Steel Corrosion in Bridge Decks and Reinforced Concrete Pavement, HR-156, 1977

The Iowa Department of Transportation initiated this research to evaluate the reliability, benefit and application of the corrosion detection device. Through field testing prior to repair projects and inspection at the time of repair, the device was shown to be reliable. With the reliability established, twelve additional devices were purchased so that this evaluation procedure could be used routinely on all repair projects. The corrosion detection device was established as a means for determining concrete removal for repair. Removal of the concrete down to the top reinforcing steel is required for all areas exhibiting electrical potentials greater than 0.45 Volt. It was determined that the corrosion detection device was not applicable to membrane testing. The corrosion detection device has been used to evaluate corrosion of reinforcing steel in continuously reinforced concrete pavement.

Prevention of Reflection Cracking in Asphalt Overlays with Structofors, Petromate, and Cerex, HR-158, 1977

This report presents construction methods and results using three reinforcing fabrics to prevent reflection cracking in an asphalt overlay. The original highway in the rural area was Portland Cement Concrete 20 feet wide. It was widened by adding 2 feet of asphaltic concrete 10 inches deep on each side prior to resurfacing. Data are presented for the widening joint and transverse cracks in the rural area and for the random cracking in the urban area.

Fibrous Concrete Resurfacing Greene County, Iowa, HR-165, 1977

The three miles of fibrous concrete resurfacing in Greene County, Iowa were placed in September and early October, 1973. It was recognized in advance that cracking and other performance characteristics of the fibrous concrete sections and of the control sections would be major factors in the evaluation of the project. A low level aerial survey was made of the old pavement. During construction of the resurfacing, the aerial survey was checked to insure that cracks in the old pavement were referenced to the 100 ft. station marks placed in the resurfacing. Crack surveys have been conducted on dates indicated below. Additional cracks found at each subsequent survey are shown in a color matching the date notation. April, 1974 November, 1974 October, 1975 October, 1976 October, 1977

Effects of Reduced Intersection Lighting on Nighttime Accident Frequency, HR-1003A, 1977

The first phase of the study of intersection lighting and accidents conducted using data from 1964 through 1971 yielded the conclusion that the installation of intersection lighting reduced the nighttime accident frequency by 52%. With this conclusion, this project (the second phase), was initiated to determine the relative benefit of a higher level of lighting as opposed to minimum lighting. Twenty pairs of intersections with similar geometrics were selected. Some lights were turned out at one intersection of each pair to produce a lighting level differential. Based on the results of this research, the lighting level of lighted rural at-grade intersections does not have a significant effect on the accident frequency. At the nineteen "reduced lighting" intersections, the number of lighted luminaires was reduced from 101 to 46 with a corresponding reduction in energy consumption of over 100,000 Kilowatt hours per year. This energy conservation measure could reduce consumption by an estimated 1,000,000 Kilowatt hours per year if initiated on more than 200 earlier primary, rural installations.

Low Profile Marker for Wet/Night Visibility, HR-1005, 1977

Conventional highway lane markings are ineffective at night, particularly when the pavement is wet. There is a recognized need for a system that is effective at night under wet conditions and where there is no reduction in current daytime standards. To be effective at all times the system must maintain wet-night retroreflective properties while resisting deterioration caused by snowplows, studded tires, sand and salt applications, and lane changing maneuvers by traffic. This project tested a system of low-profile lane markers developed by Battelle Columbus Laboratory under contract with the Implementation Division of the Federal Highway Administration.

Chloride Penetration Into LSDC (Iowa System) Resurfacing Mixes, MLR-77-05 and R-267, 1977

The purpose of this investigation was to determine the comparative effectiveness of standard D-57 concrete and Iowa system Low Slump Dense Concrete in preventing threshold levels of chloride from penetrating the concrete slabs to the reinforcing steel.

Resources for career education, 1977.

This document contains a multitude of resources for career education available to Iowans from many sources.

Ativação de defesa em cacaueiro contra a murcha-de-verticílio por extratos naturais e acibenzolar-S-metil

O objetivo deste trabalho foi avaliar o potencial de extratos fúngicos e vegetais na redução da murcha-de-verticílio do cacaueiro, as atividades da peroxidase e polifenoloxidase e o conteúdo de lignina. Mudas de cacaueiro foram pulverizadas com filtrado de micélio de Rhizopus sp. (FMR), quitosana de Rhizopus sp. (QMR) e Trichoderma sp. (QMT), extratos de casca in natura e seca de maracujá, extrato metanólico de casca seca de frutos de maracujá (MMS) e acibenzolar-S-metil (ASM - 0.2 mg mL-1) e sete dias depois, submetidas à inoculação de Verticillium dahliae. O ASM reduziu a murcha-de-verticílio em 38,0%, seguido dos extratos FMR, QMT, MMS e QMR, que apresentaram reduções em 22,8, 20,1, 19,2 e 15,7%, respectivamente, em relação à testemunha. Plantas pulverizadas com ASM ou FMR seguidas de inoculação apresentaram aumento da atividade de peroxidase aos oito dias após a pulverização, comparadas às respectivas testemunhas, com pico aos 18 dias após a pulverização. ASM e FMR aumentaram a atividade de polifenoloxidase aos quatro dias após a pulverização. Maiores concentrações de lignina foram obtidas em plantas tratadas com FMR e FMR seguido de inoculação. FMR é um potencial indutor de resistência para manejo de murcha-de-verticílio em cacaueiro.

Vladimir ha dit... Identitat, xarxes socials i ciberperdiodisme en els blocs. Una construcció de la intersubjectivitat dins la nova Internet

DEA (tesina) que analitza quin és el paper que juguen els blocs dintre de la Web 2.0, articulant-se al voltant de tres eixos: la creació de la identitat virtual, les xarxes socials generades a través de la blocosfera i les implicacions econòmiques i socials que se'n deriven. La pregunta central és de quina manera, si ho fan, els blocs contribueixen a modificar fòrmules de lectura i participació tant d'àmbit personal com públic en les agendes informatives. I si aquesta participació genera canvis significatius a nivell econòmic i psicosocial.