bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Detergents on the Redistribution of Gangliosides and GPI-anchored Proteins in Brain Tissue Sections
Authors: Heffer-Lauc Marija , Viljetić Barbara , Vajn Katarina , Schnaar Ronald L. , Lauc Gordan
Published: April 2007

Gangliosides and glycosylphosphatidylinositol (GPI)-anchored proteins contain lipid tails that tether them to the outer side of the cell membrane. This mode of association with the cell membrane enables them to take part in the organization of lipid rafts, but it also permits gangliosides and GPI-anchored proteins to be actively released from one cell and inserted into the membrane of another cell. Recently, we reported that under conditions of lipid raft isolation, Triton X-100 causes significant redistribution of both gangliosides and GPI-anchored proteins. Aiming to find a less disruptive detergent, we evaluated the effects of CHAPS, Saponin, deoxycholic acid, Trappsol, Tween 20, Triton X-100, Brij 96V, Brij 98, and SDS on brain tissue sections. At room temperature, all detergents (1% concentration) extracted significant amounts of both gangliosides and Thy-1. At 4C, the extraction was weaker, but Triton X-100, CHAPS, and deoxycholic acid caused significant redistribution of GD1a and Thy-1 from gray matter into the white matter. Both redistribution and extraction were significantly augmented when sections were incubated with detergents in the presence of primary antibodies. Of the nine tested detergents, none is the ideal choice. However, Brij 96V appears to be able to sufficiently reveal myelin epitopes while causing the least amount of artifacts. This manuscript contains online supplemental material at http://www.jhc.org . Please visit this article online to view these materials. (J Histochem Cytochem 55: 805–812, 2007)
Optimization of floridoside production in the red alga Mastocarpus stellatus: pre-conditioning, extraction and seasonal variations
Authors: Kerjean Véronique , Morel Bénédicte , Stiger Valérie , Bessières Marie-Anne , Simon-Colin Christèle , Magné Christian , Deslandes Eric
Published: April 2007

The red alga Mastocarpus stellatus is widely found on the coastline of Brittany (France) and it was previously reported to contain high amounts of floridoside, a well-known glycoside in red algae. Therefore, we aimed at evaluating the potential interest of M. stellatus for industrial purposes. Floridoside extraction was optimized, hydroethanolic mixture being the most efficient extractant compatible with industrial requirements. Floridoside yield was increased significantly through pre-treatment and conditioning of the alga before extraction. Thus, salt stress and drying procedure both resulted in an increase in floridoside concentration. Studies of seasonal variations of floridoside content in this species showed that maximal levels were recovered in autumn. We now propose an optimized procedure for M. stellatus valorization, especially for biomedical applications.
Evolution of Coadaptation in a Subdivided Population
Authors: Takahasi K Ryo
Published: April 2007

The interplay between population subdivision and epistasis is investigated by studying the fixation probability of a coadapted haplotype in a subdivided population. Analytical and simulation models are developed to study the evolutionary fate of two conditionally neutral mutations that interact epistatically to enhance fitness. We find that the fixation probability of a coadapted haplotype shows a marked increase when the population is genetically subdivided and subpopulations are loosely connected by migration. Moderate migration and isolation allow the propagation of the mutant alleles across subpopulations, while at the same time preserving the favorable allelic combination established within each subpopulation. Together they create the condition most favorable for the ultimate fixation of the coadapted haplotype. On the basis of the analytical and simulation results, we discuss the fundamental role of population subdivision and restricted gene flow in promoting the evolution of functionally integrated systems, with some implications for the shifting-balance theory of evolution.
The Genetic Basis of Zinc Tolerance in the Metallophyte Arabidopsis halleri ssp. halleri (Brassicaceae): An Analysis of Quantitative Trait Loci
Authors: Willems Glenda , Dräger Dörthe B , Courbot Mikael , Godé Cécile , Verbruggen Nathalie , Saumitou-Laprade Pierre
Published: April 2007

The species Arabidopsis halleri, an emerging model for the study of heavy metal tolerance and accumulation in plants, has evolved a high level of constitutive zinc tolerance. Mapping of quantitative trait loci (QTL) was used to investigate the genetic architecture of zinc tolerance in this species. A first-generation backcross progeny of A. halleri ssp. halleri from a highly contaminated industrial site and its nontolerant relative A. lyrata ssp. petraea was produced and used for QTL mapping of zinc tolerance. A genetic map covering most of the A. halleri genome was constructed using 85 markers. Among these markers, 65 were anchored in A. thaliana and revealed high synteny with other Arabidopsis genomes. Three QTL of comparable magnitude on three different linkage groups were identified. At all QTL positions zinc tolerance was enhanced by A. halleri alleles, indicating directional selection for higher zinc tolerance in this species. The two-LOD support intervals associated with these QTL cover 24, 4, and 13 cM. The importance of each of these three regions is emphasized by their colocalization with HMA4, MTP1-A, and MTP1-B, respectively, three genes well known to be involved in metal homeostasis and tolerance in plants.
High Frequency of Mutations That Expand the Host Range of an RNA Virus
Authors: Ferris Martin T , Joyce Paul , Burch Christina L
Published: April 2007

The ability of a virus population to colonize a novel host is predicted to depend on the equilibrium frequency of potential colonists (i.e., genotypes capable of infecting the novel host) in the source population. In this study, we investigated the determinants of the equilibrium frequency of potential colonists in the RNA bacteriophage ϕ6. We isolated 40 spontaneous mutants capable of infecting a novel Pseudomonas syringae host and sequenced their host attachment genes to identify the responsible mutations. We observed 16 different mutations in the host attachment gene and used a new statistical approach to estimate that 39 additional mutations were missed by our screen. Phenotypic and fitness assays confirmed that the proximate mechanism underlying host range expansion was an increase in the ability to attach to the novel host and that acquisition of this ability most often imposed a cost for growth rate on two standard hosts. Considered in a population genetic framework, our data suggest that host range mutations should exist in phage populations at an equilibrium frequency (3 × 10−4) that exceeds the phage mutation rate by more than two orders of magnitude. Thus, colonization of novel hosts is unlikely to be limited by an inability to produce appropriate mutations.
Variance of the Parental Genome Contribution to Inbred Lines Derived From Biparental Crosses
Authors: Frisch Matthias , Melchinger Albrecht E
Published: April 2007

The expectation of the parental genome contribution to inbred lines derived from biparental crosses or backcrosses is well known, but no theoretical results exist for its variance. Our objective was to derive the variance of the parental genome contribution to inbred lines developed by the single-seed descent or double haploid method from biparental crosses or backcrosses. We derived formulas and tabulated results for the variance of the parental genome contribution depending on the chromosome lengths and the mating scheme used for inbred line development. A normal approximation of the probability distribution function of the parental genome contribution fitted well the exact distribution obtained from computer simulations. We determined upper and lower quantiles of the parental genome contribution for model genomes of sugar beet, maize, and wheat using normal approximations. These can be employed to detect essentially derived varieties in the context of plant variety protection. Furthermore, we outlined the application of our results to predict the response to selection. Our results on the variance of the parental genome contribution can assist breeders and geneticists in the design of experiments or breeding programs by assessing the variation around the mean parental genome contribution for alternative crossing schemes.
Genetic Modifiers of Drosophila Palmitoyl–Protein Thioesterase 1-Induced Degeneration
Authors: Buff Haley , Smith Alexis C , Korey Christopher A
Published: April 2007

Infantile neuronal ceroid lipofuscinosis (INCL) is a pediatric neurodegenerative disease caused by mutations in the human CLN1 gene. CLN1 encodes palmitoyl–protein thioesterase 1 (PPT1), suggesting an important role for the regulation of palmitoylation in normal neuronal function. To further elucidate Ppt1 function, we performed a gain-of-function modifier screen in Drosophila using a collection of enhancer–promoter transgenic lines to suppress or enhance the degeneration produced by overexpression of Ppt1 in the adult visual system. Modifier genes identified in our screen connect Ppt1 function to synaptic vesicle cycling, endo-lysosomal trafficking, synaptic development, and activity-dependent remodeling of the synapse. Furthermore, several homologs of the modifying genes are known to be regulated by palmitoylation in other systems and may be in vivo substrates for Ppt1. Our results complement recent work on mouse Ppt1−/− cells that shows a reduction in synaptic vesicle pools in primary neuronal cultures and defects in endosomal trafficking in human fibroblasts. The pathways and processes implicated by our modifier loci shed light on the normal cellular function of Ppt1. A greater understanding of Ppt1 function in these cellular processes will provide valuable insight into the molecular etiology of the neuronal dysfunction underlying the disease.
DDB2, DDB1A and DET1 Exhibit Complex Interactions During Arabidopsis Development
Authors: Al Khateeb Wesam M , Schroeder Dana F
Published: April 2007

Damaged DNA-binding proteins 1 and 2 (DDB1 and DDB2) are subunits of the damaged DNA-binding protein complex (DDB). DDB1 is also found in the same complex as DE-ETIOLATED 1 (DET1), a negative regulator of light-mediated responses in plants. Arabidopsis has two DDB1 homologs, DDB1A and DDB1B. ddb1a single mutants have no visible phenotype while ddb1b mutants are lethal. We have identified a partial loss-of-function allele of DDB2. To understand the genetic interaction among DDB2, DDB1A, and DET1 during Arabidopsis light signaling, we generated single, double, and triple mutants. det1 ddb2 partially enhances the short hypocotyl and suppresses the high anthocyanin content of dark-grown det1 and suppresses the low chlorophyll content, early flowering time (days), and small rosette diameter of light-grown det1. No significant differences were observed between det1 ddb1a and det1 ddb1a ddb2 in rosette diameter, dark hypocotyl length, and anthocyanin content, suggesting that these are DDB1A-dependent phenotypes. In contrast, det1 ddb1a ddb2 showed higher chlorophyll content and later flowering time than det1 ddb1a, indicating that these are DDB1A-independent phenotypes. We propose that the DDB1A-dependent phenotypes indicate a competition between DDB2- and DET1-containing complexes for available DDB1A, while, for DDB1A-independent phenotypes, DDB1B is able to fulfill this role.
Integrative Mapping of Gossypium hirsutum L. by Meiotic Fluorescent in Situ Hybridization of a Tandemly Repetitive Sequence (B77)
Authors: Ji Yuanfu , Zhao Xinping , Paterson Andrew H , Price H James , Stelly David M
Published: April 2007

We determined the relative positions of the tandem-repeat molecular cytogenetic marker B77, translocation breakpoints, and telosome arms in Gossypium hirsutum cytogenetic stocks by fluorescence in situ hybridization (FISH) analysis of meiotic quadrivalents in 16 single and 2 double translocation heterozygotes and five monotelodisomics. Results delimited the B77 FISH locus to the right arm of the D-subgenome chromosome 14 (14R) and the short arm (14sh), respectively. By equating 14R with 14sh and 14L (left) with 14Lo (long), the findings established a unified nomenclature for the arms of chromosome 14. Previously reported chromosome 14 arm locations were confirmed for four of the five translocations involving chromosome 14, namely NT1L-14L (2780), NT2R-14R (2B-1), NT14L-23R (2777), and NT14R-24R (2781), whereas the location of breakpoint T6L-14L was not confirmed and was reassigned to arm 14R. When used as a probe on Southern blots, the B77 signal was associated with a terminus of the D-subgenome RFLP linkage group (LG) D04 by linkage analysis of an interspecific F2 population, now known to be chromosome 20. However, additional codominant DNA marker information in the affected region excluded the B77 polymorphism detected by Southern blot hybridization from chromosome 20 and, indeed, from the remainder of the genome.
Partnerships for improving water utility management in Africa
Authors: Mugabi J. , Kayaga S. , Njiru C.
Published: April 2007

Urban water utilities in developing countries face enormous challenges in meeting the water needs of growing urban populations. Many of the challenges stem from poor utility management practices and the lack of a commercially oriented culture. For many years the debate on how to address this problem has been dominated by two extremes. On the one hand, private sector participation (PSP) has had only limited success. On the other, public management reform, which urges the creation of incentives for public utilities to become more efficient and commercially oriented, has not yet taken hold due to the slow pace of institutional reforms in developing countries. Given this situation, major players in the sector are seeking alternative approaches to improving utility management and performance in developing countries. Such alternative approaches include innovative multi-sector partnerships between private, public and civil society. This paper discusses a partnering approach (pioneered by the Water Utility Partnership (WUP) of Africa) between Loughborough University, Severn Trent Water, six African water utilities and utility management consultants. The aim of the partnership is to increase the management capacity of utility companies in order to improve the performance of water utilities in Africa. This innovative model has implications for policy and practice in this field.
2020 Liverpool—performance and value for money
Authors: Kilner R. G. , Founds C.
Published: April 2007

2020 Liverpool Ltd is a joint venture company owned by Mouchel Parkman and Liverpool City Council. It was set up in 2003 to deliver technical professional services to the City Council and other public and private sector clients. It is a fully functioning company and all staff are employed directly by the company. The company has a 10 year service contract with the Council, which has an optional renewal for a further 10 years. The partnership is performance based with key measures including efficiency saving, delivery of programmes, reliability of estimates, and customer satisfaction. This paper describes how these are measured and experience to date. In addition the partnership has devised and implemented a methodology for assessing value for money, which this paper also describes. It is believed that the 2020 model is the closest to that used in the manufacturing industry from which the concepts used in the public arena have been derived.
Analysis of public–private partnerships for China's water service
Authors: Kayaga S. , Zhe L.
Published: April 2007

The private sector in China has been growing since economic reforms were launched in the late 1970s. The massive demand for new infrastructure and improved service levels have precipitated the growth of public–private partnership (PPPs) in the Chinese water urban sector. Although the number of water and wastewater infrastructure projects financed through PPPs had risen to over 130 by the 2004, with an investment commitment of over US$4·8 billion, PPPs still accounted for less than 2% of total investments in the water sector. An institutional analysis was conducted in 2005 to find out how conducive PPPs are for provision of water services in Longgang, a coastal town in the Zhejiang Province of China. Although the operational performance indicators were generally above average, subjective assessment of the internal environment uncovered several gaps, which could be addressed by adopting an appropriate mode of PPPs. A scan of the external environment revealed conditions that are largely conducive to the introduction of PPPs in Longgang Water Utility. This paper showed how an existing institutional analysis framework could be adapted for assessing the suitability of introducing PPPs in water utilities.
Corn Stalk Response to Plant Population and the Bt–European Corn Borer Trait
Authors: Stanger Trenton F. , Lauer Joseph G.
Published: April 2007

Current research indicates that plant populations should increase above the current Wisconsin recommendation of 74 100 plants ha−1 for higher corn (Zea mays L.) grain yields. However, stalk lodging is a major constraint to increasing plant populations. One option growers have is using Bt (Bacillus thuringiensis) hybrids, which are known to lodge less. A new method for assessing stalk lodging risk is needed. The objectives of this study were to (i) assess rind strength of corn hybrids with or without the Bt trait to increasing plant populations at natural levels of European Corn Borer [ECB, Ostrinia nubilalis (Hübner)], and (ii) determine the potential of rind strength measurements for predicting stalk lodging. In 2003 and 2004, rind penetrometer resistance (RPR) was used to measure rind strength for four Bt and five non‐Bt hybrids with plant populations ranging from 64 220 to 123 500 plants ha−1 at 10 locations in Wisconsin. Stalk lodging increased from 6 to 18% as plant population increased, and only at one location, Arlington, did Bt hybrids lodge significantly less (20 vs. 42%) than non‐Bt hybrids. The RPR of both Bt and non‐Bt hybrids decreased from 3.9 to 3.7 load‐kg plant−1 with increasing plant population. Plants with rind strength measurements < 3.9 load‐kg plant−1 taken at physiological maturity showed more lodging. Thus, such measurements appear to be a good indicator of stalk lodging potential in a high plant population situation. This new method has potential to help growers prepare for grain harvest by identifying fields with plants having average RPR below a 3.9 load‐kg plant−1 threshold, and adjusting harvest schedules of suspect fields earlier to avoid yield losses caused by stalk lodging. Further research using more hybrids across a range of environmental conditions and plant populations will be necessary to fully understand the importance of this tool and its potential importance in understanding and identifying high lodging potential environments.
Response of Coastal Bermudagrass Yield and Nutrient Uptake Efficiency to Nitrogen Sources
Authors: Silveira Maria L. , Haby Vincent A. , Leonard Allen T.
Published: April 2007

Nitrogen is an important agronomic input for bermudagrass production in the southern USA. Fertilizers that can efficiently provide N to grass pastures and hay meadows are an important issue because of increasing costs and environmental problems associated with N losses. This experiment was designed to determine the effectiveness of various N sources on ‘Coastal’ bermudagrass [Cynodon dactylon (L.) Pers.] production and N uptake efficiency. Nitrogen was applied at 0, 45, 90, and 135 kg ha−1 harvest−1 as urea–ammonium nitrate (UAN), urea, ammonium nitrate (AN) and ammonium sulfate (AS) on Gallime (Glossic Paleudalf) and Lilbert (Plinthic Paleudult) soils. Mixtures of S with UAN and of Ca and B with urea were also evaluated. Bermudagrass was periodically harvested and subsampled for total N analysis. At termination of the study soil samples were collected for pH and extractable NO3–N analyses. Bermudagrass yield responses to N sources were significant only in the Gallime soil. In this soil, AN and AS increased yields and resulted in greater N uptake compared to urea and UAN. Lilbert soil showed no effect of N sources on dry matter (DM) production. There was a yield response to N rates and maximum bermudagrass production was generally achieved at the 90 kg ha−1 N rate regrowth−1. Fertilizer efficiency declined as the N rate was increased. Soil acidity increased in response to N application, particularly for the AS treatments. Selection of N sources and rates should be carefully planned to avoid detrimental effects on soil acidity and, consequently, fertilizer efficiency.
Winter Cereal, Seeding Rate, and Intercrop Seeding Rate Effect on Red Clover Yield and Quality
Authors: Blaser Brock C. , Singer Jeremy W. , Gibson Lance R.
Published: April 2007

Diversification of corn (Zea mays L.)–soybean [Glycine max (L.) Merr.] cropping systems can be achieved by incorporating winter cereal grains. Winter cereal grain production systems in the northern USA are inefficient in respect to annual radiation capture because the majority of these fields lay fallow until the following cropping season. The addition of a red clover (Trifolium pratense L.) intercrop to winter cereal grains can supply forage and provide N to subsequent crops. The objective of this study was to determine the red clover dry matter (DM) and forage quality response to winter cereal species, cereal seeding rate, and red clover seeding rate. Winter wheat (Triticum aestivum L.) and triticale (×Triticosecale spp.) were seeded at 100, 200, 300, and 400 seed m−2 in October 2002 and 2003. In March, red clover was frost‐seeded at 300, 600, 900, 1200, and 1500 seed m−2 Red clover harvests in late summer, early fall, and the following spring yielded 6.2 to 8.5 Mg ha−1 DM. Winter cereal species only affected red clover DM in the following spring of 1 yr. Cereal seeding rates impacted DM within specific harvest periods, but had no effect on seasonal totals or spring DM. Increasing red clover seeding rates increased final DM yield in four of six harvests. Increasing red clover seeding rate had no consistent effect on forage quality. Producers that intercrop red clover in winter wheat or triticale should frost‐seed at 900 to 1200 seed m−2 to maximize DM yield.
The effect of aluminium on bioelectrical activity of the Nitellopsis obtusa cell membrane after H+-ATPase inhibition
Authors: Kisnierienë Vilma , Sakalauskas Vidmantas
Published: April 2007

Aluminium induced membrane potential (Em) changes and potential changes during repolarization phase of the action potential (AP) in the internodal cells of Nitellopsis obtusa after blocking H+-ATPase activity by DCCD were investigated. Micromolar concentrations of DCCD are sufficient to give complete and irreversible inhibition of proton pumping. The membrane potential was measured by conventional glass-microelectrode technique. We found that the half-amplitude pulse duration differs significantly between standard conditions, after DCCD application, and after H+-ATPase blocking and subsequent Al3+ treatment: 4.9, 7.7 and 17.2 seconds, respectively. We propose that in the short term (2 hours) treatment of Al3+, the decrease in membrane potential was compensated for by H+-ATPase activity. Blocking H+-ATPase activity by DCCD can enhance the influence of Al3+ on the bioelectrical activity of cell membranes.
Structure of cyano-bridged Eu(III)—Co(III) bimetallic assembly and its application to photophysical verification of photomagnetic phenomenon
Authors: Akitsu T. , Einaga Y.
Published: April 2007

New crystal structure of Eu(DMF)4(H2O)3Co(CN)6·H2O (DMF = N,N′-dimethylformamide) (Eu-Co) has been determined to be monoclinic, P2(1)/n, a = 19.796(12) Å, b = 8.862(11) Å, c = 17.525(10) Å, β = 96.26(5)°, V = 3056(5) Å3, Z = 4. The Eu(III) ion adopts an antiprismatic eight-coordination and forms a cyano bridge with r(Eu-N) = 2.496(7) Å and Θ(Eu-N-C) = 165.7(7)° to the Co(III) ion. The complex exhibits some common features with the Eu-Fe complex. Diffuse reflectance electronic spectra and magnetic susceptibility of Eu-Cr, Eu-Mn, Eu-Fe, and Eu-Co complexes were compared. By substituting the metal ions, both electronic and structural features affected the charge transfer bands and superexchange interactions concerning cyanide ligands. In addition, only Eu-Co exhibited 5 D 0 → 7 F 2 and 5 D 0 → 7 F 1 luminescence bands at 16300 cm−1 and 16900 cm−1, respectively at 298 K (λex = 360 nm (27000 cm−1)), because quenching by cyano-bridged ions did not prevent Eu(III) ion from exhibiting emission. Thus, only Eu-Co may be suitable for verification of an assumption of mechanism concerning drastic photoinduced magnetic changes for Nd-Fe. Merely small decrease of magnetization was observed for Eu-Co after UV light irradiation at 2.0 K. This result was attributed to slight structural changes around cyano bridges without transitions of spin states.
Improved DPPH determination for antioxidant activity spectrophotometric assay
Authors: Szabo M. , Idiţoiu C. , Chambre D. , Lupea A.
Published: April 2007

An improved procedure for determination of the residual DPPH (1,1-diphenyl-2-picrylhydrazyl) free radical concentration was proposed taking into account the absorbance of both DPPH free radicals and DPPH nonradical (1,1-diphenyl-2-picrylhydrazine) stable form. The calculated residual DPPH free radical concentrations were compared with those obtained from a calibration curve and variation coefficients below 10 % were found.
Synthesis of new condensed and cyclized coumarin derivatives
Authors: Dekić S. , Dekić V. , Dekić B. , Dekić M.
Published: April 2007

Condensation of 4-chloro-2-oxo-2H-chromene-3-carbonitrile with selected heteroarylamines in acetonitrile containing a catalytic amount of triethylamine, followed by intramolecular cyclization, gave the new coumarin derivatives with yields ranging from 43 % to 78 %. The novel compounds were subjected to acid hydrolysis giving the corresponding oxo derivatives in 66–70 % yield. The structural assignments of the synthesized compounds were based on elemental, IR, 1H and 13C NMR analyses.
Innovative Approach to Fatigue Crack Propagation in Concrete Pavements
Authors: Aglan Heshmat A. , Bayomy Fouad M.
Published: April 2007

An innovative approach to characterize the micro- and macromechanical damage phenomena resulting from fatigue cracking and relate them to the design and durability of pavements has been developed. In this approach, crack propagation and its associated damage are considered as irreversible processes, and hence the general framework of the thermodynamics of irreversible processes is used to model fatigue crack propagation behavior. A constitutive equation, the modified crack layer model, is used to extract material parameters characteristic of the pavement’s resistance to fatigue crack propagation. These parameters are the specific energy of damage, γ′, and a dissipative characteristic, β′, of the paving mixture. The general applicability of the proposed approach has been extended to examine fatigue crack propagation data of concrete reported in the literature. It is found that the proposed model describes fatigue crack propagation behavior of concrete pavements over the entire range of the crack driving force.
Reliability Design of Flexible Airfield Pavements: Elastic Layered Method
Authors: Chou Yu T.
Published: April 2007

A design procedure was developed for layered elastic flexible airfield pavement systems in terms of probability and reliability. A user-friendly computer program, RELIFLEX, was prepared to carry out the computations. The Rosenblueth method is used to estimate the expected value and variance of the computed strains (dependent parameters) on the basis of the input mean values of independent parameters (i.e., aircraft load, layer thicknesses, and material moduli). RELIFLEX has the capability of considering the strain distribution to be normal, lognormal, or beta, and a capacity-demand analysis is included. Only normal distribution is presented. Environmental effects and the lack of fit of the prediction models are not considered in RELIFLEX. The relationships between the reliability level and the allowable strain repetition of the designed system, established using RELIFLEX, provide a decision-making tool for engineers to design pavement at the desired reliability level. For a desired reliability level of the design system, pavement thickness can be varied to agree with the designed coverage or the allowable coverage can be modified for a given pavement thickness.
Improved Methodology for Developing a Long-Range Pavement Rehabilitation Program
Authors: Wang Li , Darter Michael I. , Hall Kathleen T. , Lu Yan , Lippert David L.
Published: April 2007

Current methodologies for developing, evaluating, and improving longrange rehabilitation programs may be classified as manual or analytical. The major limitation of manual methods is that although they are practical, they are not cost-effective because of the difficulties of comparing potential cost/benefit trade-offs among alternatives. Analytical methods, on the other hand, are more cost-effective but often not practical, because they oversimplify the real problem into a mathematical model and do not allow engineers and managers to be involved in the decision-making process. A new methodology and new concepts to overcome these major deficiencies were developed and implemented. The first of the new concepts is the use of graphical data interpretation and “visual thinking.” The second is that pavement performance evaluation should be comprehensive and quickly accessible. The third is that human knowledge should be involved in the decision-making process through a user-friendly interface. The fourth is that the relationships among the components of the methodology should be flexible rather than rigid. Finally, the process should be efficiently repeatable so that a satisfactory long-term rehabilitation program can be developed. A user-friendly, Windows-based pavement management system, called Windows ILLINET, was produced in this study on the basis of the new methodology and concepts.
The Florida Pier Analysis Program Methods and Models for Pier Analysis and Design
Authors: Hoit Marc , Hays Cliff , McVay Mike
Published: April 2007

The Florida Pier Analysis Program (FLPIER) was developed by the University of Florida Department of Civil Engineering in conjunction with the Florida Department of Transportation (FDOT) Structures Division. The program was developed in order to give pier designers a comprehensive model development and analysis tool to optimize pier designs. The current version is a nonlinear, static, soil-structure interaction suite of programs that run on a personal computer and include group pile effects, layered soil, pier columns and cap, high mast lighting, sound, and retaining walls. The program was designed to allow input to be specified graphically using “designer variables” such as spacing, offsets, number of columns, and so forth. Its use has reduced the time for model development and analysis from days to under an hour. The numerical modeling techniques used have been compared with experimental data and give highly accurate results leading to an improved overall design and reduced costs.
Linear Tracking Response Measurements: Determining Effects of Wheel-Load Configurations
Authors: Groenendijk J. , Vogelzang C. H. , Molenaar A. A. A. , Mante B. R. , Dohmen L. J. M.
Published: April 2007

The relative strain effects of 15 different load configurations were studied. Using the linear tracking device (LINTRACK) accelerated loading facility, two 5-year-old pavements of 0.15-m asphalt on sand (one virgin and one loaded with 4 million 75-kN wheel loads) were tested. All measured strains were converted to strain factors relative to a standard load (super-single tire, 50 kN, 0.70 MPa). The results were compared with earlier measurements and BISAR-calculated factors. The results on the loaded pavement showed markedly more variation than those on the unloaded pavement. Generally, the BISAR-calculated relative strain factors matched the measured values well for the super-single tire. Considerable difference occurred only in the most extreme load conditions. Nonuniform contact stress distribution can be the cause for this. The calculated relative strain factors for the dual tire configurations underestimated the measured values.
Rutting Development in Linear Tracking Test Pavements To Evaluate Shell Subgrade Strain Criterion
Authors: Groenendijk J. , Vogelzang C. H. , Miradi A. , Molenaar A. A. A. , Dohmen L. J. M.
Published: April 2007

Two full-depth gravel asphalt concrete (AC) pavements of 0.15- and 0.08-m thickness on a sand subgrade were loaded with 4 million and 0.65 million repetitions of a 75-kN super-single wheel load using the linear tracking device (LINTRACK), a heavy-traffic simulator. Frequent measurements of asphalt strains, temperatures, rutting, cracking, and falling weight deflectometer (FWD) were made. The data analysis of the rutting measurements indicates that all rutting could be ascribed to subgrade deformation (secondary rutting). No evidence was found of shear deformation within the asphalt layer (primary rutting). The data analysis also indicates that the observed rutting performance of the LINTRACK test sections (to a maximum rut depth of 18 mm) coincides closely with the average criterion from the Shell Pavement Design Manual, which relates subgrade strain to allowable number of strain repetitions.
Roadway-Vehicle Interaction, Physical Indexes, and Human Judgment of Ride Quality
Authors: Liu Chiu , Herman Robert
Published: April 2007

Present serviceability index (PSI) modeling has been an important subject for decades. Other dynamic indexes characterizing a roadway such as the international roughness index (IRI), averaged rectified slope (ARS), and averaged rectified speed (ARV) have been proposed and studied. However, the roles played by these indexes in the interaction between road, vehicle, and human ratings have not been made clear. A unified physical model linking the static profile of a roadway and the dynamic response of a vehicle to the profile to the serviceability index of the roadway is presented here. Analytical expressions for jerk index, acceleration index, ARV, ARS, and IRI are derived from the developed model in terms of the physical parameters for roadways and the dynamic characteristics of a vehicle. Then a linear relation between the PSI and the logarithm of the jerk index is proposed. Using the jerk index computed from field profile data, the linear functional form for the PSI is verified, and regression R2 values higher than 0.94 are obtained for various types of pavements. The same analysis is performed for other dynamic indexes, and the R2 values are found to be approximately in the range from 0.70 to 0.80. These results indicate that the theoretical model correctly predicts and explains the human rating of ride quality and that the jerk experienced by raters in a moving vehicle dictates the ratings. Moreover, the relationship of the static parameters of roadway profiles with human ratings is discussed using the conventional approach.
Using Artificial Neural Networks as a Forward Approach to Backcalculation
Authors: Meier Roger W. , Alexander Don R. , Freeman Reed B.
Published: April 2007

In recent years, artificial neural networks have successfully been trained to backcalculate pavement layer moduli from the results of falling weight deflectometer (FWD) tests. These neural networks provide the same solutions as existing programs, only thousands of times faster. Unfortunately, their use is constrained to the test conditions assumed during network training. These limitations arise from practical aspects of neural network training and cannot be circumvented easily. The goal of this research was to develop a backcalculation program combining the speed of neural networks and the flexibility of conventional programs to produce the same solutions as existing programs. This was accomplished by forgoing neural network backcalculation in favor of neural network forward-calculation, that is, using neural networks in place of complex numerical models for computing the forward-problem solutions used by the conventional backcalculation programs. A suite of neural networks, covering a range of flexible pavement structures, was trained using data generated by WESLEA, the forward-problem solver used in the WESDEF backcalculation program. When tested on 110 experimental FWD results, a version of WESDEF augmented by the neural networks provided statistically identical answers 42 times faster, on average, than the original. Provisions have been made for periodic upgrades as additional networks are trained for other pavement types and test conditions. Meanwhile, the original WESLEA can still be used when an appropriate network is unavailable. This preserves the flexibility of the original program while taking maximum advantage of the speed gains afforded by the neural networks.
Evasion of Weight-Enforcement Stations by Trucks
Authors: Cunagin Wiley , Mickler W. A. , Wright Charles
Published: April 2007

Highway engineers have become increasingly concerned about the deterioration of the nation’s highway pavements. They suspect that overweight trucks are a primary cause of the problem. Before 1979, the data needed to assess the magnitude of the overweight-truck problem did not exist. Consequently, several studies were conducted to address the magnitude and location of overweight trucking. These studies included efforts to improve truck weight-enforcement programs and to assess the feasibility of using weigh-in-motion (WIM) equipment for weight enforcement. The Florida Department of Transportation (FDOT) undertook the study documented in this paper. The objective of the study was to assess the magnitude, expressed in equivalent single-axle loads (ESALs), of the problem of avoidance of weight-enforcement stations by overweight trucks. The study also considered whether bypassing traffic was local or interstate. FDOT selected the I-95 corridor in the northeast corner of Florida. Two permanent weight-enforcement stations and four bypass route locations were used as traffic monitoring sites. The results of the study indicate that the numbers of overweight vehicles decrease with increasing enforcement activity, but that vehicles attempt to bypass permanent truck weight-enforcement stations. In general, the violations at the permanent weight-enforcement stations were minor, whereas those on the bypass routes were much more severe. These results, when considered with the WIM data and the experience of truck weight-enforcement officers, suggest that only intensive enforcement activity can reduce violations to low levels. Information for enforcement, especially in the definition and quantification of the scale avoidance problem, is provided. Recommendations are made concerning corridor areas and extended and random enforcement operations.
Malfunction Detection and Data Repair for Induction-Loop Sensors Using I-880 Data Base
Authors: Payne Harold J. , Thompson Stephen
Published: April 2007

Malfunction characteristics of induction-loop sensors with freeway surveillance applications are addressed. Various types of malfunctions are identified, and their respective rates are computed on the basis of data from the I-880 surveillance system in the San Francisco Bay area. Specific algorithms are presented for diagnosing each malfunction type through inspection of aggregate sensor measurements. Also addressed are methods of repairing faulty measurement data, wherein estimates of the actual traffic condition are generated utilizing measurements from adjacent lanes.
Improved Speed-Flow Relationships for Planning Applications
Authors: Skabardonis Alexander , Dowling Richard
Published: April 2007

Improved speed-estimation techniques for planning applications were developed and tested. Comparisons with field data and simulation results indicate that the recommended techniques provide better accuracy and consistency with the procedures contained in the 1994 update of the Highway Capacity Manual. These speed-estimation techniques will improve the accuracy of long-range transportation planning models for predicting travel time, delay, and air-pollutant emissions.
Saturation Flows at Signal-Group-Controlled Traffic Signals
Authors: Niittymäki Jarkko , Pursula Matti
Published: April 2007

The main goal of this research was to update the basic saturation flow values of signalized intersections. The secondary goal was to analyze the effects of certain external factors (such as weather, road, and traffic conditions) on saturation flow. The updating is based on extensive field measurements and simulations. Altogether, about 39,000 queues were observed in this study. Field measurements at 30 locations were made according to the method described in the Highway Capacity Manual and simulations were done with the Helsinki University of Technology HUT-SIM simulator, which was calibrated and carefully validated for Finnish road conditions. A summary of calibration parameters is also presented. The new base value for straight-through lanes is 1, 940 vehicles per hour; the previous value was 1, 700 vehicles per hour. In general, the updated saturation flow values of different lane types are 5 to 20 percent larger than the previous base values. The saturation flow models of different lane types are described. The effects of geometric and traffic composition factors, such as percentage of turning vehicles, traffic composition, lane width, and approach grade, were examined and modeled. Effects of weather, road surface, light conditions, and speed level were also analyzed. The drop in saturation flow was about 20 to 30 percent under slippery road and snowy conditions. In rainy conditions, the drop was smaller, about 10 percent. The effect of speed on saturation flow is also described. The most important results of this 2-year project are the saturation flow values for different lane types, knowledge of the effect of external factors (especially during winter), and the large database, which can be used for other purposes. The possibility of using special signal control programs under bad road conditions is discussed. With these kinds of programs, better safety and higher capacity can be achieved.
Operational Performance Measures of American Roundabouts
Authors: Flannery Aimee , Datta Tapan
Published: April 2007

The introduction of a new form of at-grade intersection control in the United States, termed a roundabout, has left many researchers and practitioners puzzled about their performance level. Many researchers and practitioners have looked to foreign design and operational manuals for guidance. Although the methods contained in these manuals have been implemented in their respective countries, no one is certain how they will transfer to conditions in the United States. Considering that driver characteristics are a major contributor to operational performance, these methods may not accurately depict the performance level of roundabouts with American drivers. Driver characteristics, in relation to operational performance, of four single-lane roundabouts located in the United States are described. The same driver characteristics are compared with findings in Australia under similar conditions; in addition, the probability density function for gap acceptance is derived. American drivers do not always react the same as Australian drivers under similar conditions. However, use of the Australian methods is, in most cases, more conservative and therefore should not overpredict the capacity and performance of roundabouts in the United States. The probability density function for gap acceptance at roundabouts was similar in shape and slope to that of two-way stop control. However, comparison of the gap-acceptance values of right-turning vehicles at two-way stop control with those at a roundabout indicates that drivers at roundabouts accept smaller gaps in the traffic stream on entry. This leads to the conclusion that roundabouts should perform better than two-way or all-way stop-controlled intersections under most conditions. The question remains: When do roundabouts function better than traffic signals?
Generalized Delay Model for Signalized Intersections and Arterial Streets
Authors: Fambro Daniel B. , Rouphail Nagui M.
Published: April 2007

Average delay per vehicle is the primary measure for determining the level of service at signalized intersections. This performance measure is also a major component in the calculation of average travel speed used to determine the level of service on arterial streets. The most widely used models for estimating delay at signalized intersections are those in Chapters 9 ("Signalized Intersections") and 11 ("Urban and Suburban Arterials") of the Highway Capacity Manual. This research reviewed the literature on models for estimating delay at signalized intersections to identify limitations and formulate revised models to address those limitations. Specific problems that were addressed included the inability to account for actuated-control parameters, oversaturation and variable demand, and metering and filtering by upstream traffic signals. The research team developed a generalized delay model to address these limitations and then validated the generalized model with both field and simulation data. The proposed model is sensitive to actuated-control parameter settings, oversaturation and variable demand conditions, and filtering and metering effects of upstream signals. The proposed model is also a good predictor of delays observed in the field and estimated by microscopic traffic simulation programs for the conditions studied. The generalized delay model is recommended for inclusion in future editions of the Highway Capacity Manual.
Models for Right-Turn-on-Red and Their Effects on Intersection Delay
Authors: Abu-Lebdeh Ghassan , Benekohal Rahim F. , Al-Omari Bashar
Published: April 2007

Models to estimate right-turn-on-red (RTOR) volumes at intersections with exclusive right-turn (RT) lanes are developed, and the effects of RTOR volumes on computed delay are assessed. The important variables in these models are the RT volume, followed by green-time-to-cycle (G/C) ratio, volume of conflicting traffic, and whether there is a protected phase for opposing left-turning vehicles. The estimated RTOR increased as the RTs increased. However, it decreased as G/C and the volume of conflicting traffic increased. Results show that not accounting for RTOR volumes can lead to a significant difference in delay estimates for RT lanes and, to a lesser extent, on the corresponding approaches. For RT lanes, in one-half of the cases the difference was greater than 5 percent, in more than one-quarter of the cases the difference was greater than 10 percent, and in at least one of eight cases the difference was greater than 20 percent. Differences for individual cases ranged between 0 and 130 percent, with an average of 12 percent. For approaches, the average delay difference was 4 percent, and for individual cases the difference ranged between −2 and 78 percent. As recommended by the Highway Capacity Manual, actual field counts of RTOR volume should be used whenever available. However, in the absence of such counts, the models developed here can be used and hence should be considered in capacity analysis procedures.