bluuebunny/crossref_metadata_2025 huggingface dataset:
Multitemporal Analysis of TRMM-Based Satellite Precipitation Products for Land Data Assimilation Applications
Authors: Tian Yudong , Peters-Lidard Christa D. , Choudhury Bhaskar J. , Garcia Matthew
Published: January 2008

In this study, the recent work of Gottschalck et al. and Ebert et al. is extended by assessing the suitability of two Tropical Rainfall Measuring Mission (TRMM)-based precipitation products for hydrological land data assimilation applications. The two products are NASA’s gauge-corrected TRMM 3B42 Version 6 (3B42), and the satellite-only NOAA Climate Prediction Center (CPC) morphing technique (CMORPH). The two products were evaluated against ground-based rain gauge–only and gauge-corrected Doppler radar measurements. The analyses were performed at multiple time scales, ranging from annual to diurnal, for the period March 2003 through February 2006. The analyses show that at annual or seasonal time scales, TRMM 3B42 has much lower biases and RMS errors than CMORPH. CMORPH shows season-dependent biases, with overestimation in summer and underestimation in winter. This leads to 50% higher RMS errors in CMORPH’s area-averaged daily precipitation than TRMM 3B42. At shorter time scales (5 days or less), CMORPH has slightly less uncertainty, and about 10%–20% higher probability of detection of rain events than TRMM 3B42. In addition, the satellite estimates detect more high-intensity events, causing a remarkable shift in precipitation spectrum. Summertime diurnal cycles in the United States are well captured by both products, although the 8-km CMORPH seems to capture more diurnal features than the 0.25° CMORPH or 3B42 products. CMORPH tends to overestimate the amplitude of the diurnal cycles, particularly in the central United States. Possible causes for the discrepancies between these products are discussed.
Silencing of GM3 synthase suppresses lung metastasis of murine breast cancer cells
Authors: Gu Yuchao , Zhang Junhua , Mi Wenyi , Yang Jing , Han Feng , Lu Xinzhi , Yu Wengong
Published: January 2008

Background

Gangliosides are sialic acid containing glycosphingolipids that are ubiquitously distributed on vertebrate plasma membranes. GM3, a precursor for most of the more complex ganglioside species, is synthesized by GM3 synthase. Although total ganglioside levels are significantly higher in breast tumor tissue than in normal mammary tissue, the roles played by gangliosides in breast cancer formation and metastasis are not clear.

Methods

To investigate the roles of gangliosides in breast tumor development, GM3 synthase was silenced in the highly metastatic 4T1 cells and over-expressed in the non-metastatic 67NR cells. The behavior of breast cancer cells was examined in vitro using migration assay, invasion assay, and soft agar assay. Tumor formation and metastasis in vivo were examined using a well established mouse mammary tumor model.

Results

GM3 synthase silencing in 4T1 cells significantly inhibited cell migration, invasion and anchorage-independent growth in vitro, and lung metastasis in vivo. In addition, over-expression of GM3 synthase in nonmetastatic 67NR cells significantly induced cell migration and anchorage-independent growth. Further studies indicated that activation of the phosphoinositide-3 kinase/Akt pathway, and consequently inhibition of nuclear factor of activated T cell (NFAT)1 expression, could be the mechanism underlying the suppression of breast cancer migration/invasion induced by GM3 synthase silencing.

Conclusion

Our findings indicate that GM3 synthase silencing suppressed lung metastasis in murine breast cancer cells. The molecular mechanism that underlies GM3 synthase mediated migration and invasion was inhibition of the phosphoinositide-3 kinase/Akt pathway. The findings suggest that GM3 synthase may be of value as a therapeutic target in breast cancer.
Chorionic gonadotropin induces dendritic cells to express a tolerogenic phenotype
Authors: Wan Hui , Versnel Marjan A , Leijten Lonneke M E , van Helden-Meeuwsen Cornelia G , Fekkes Durk , Leenen Pieter J M , Khan Nisar A , Benner Robbert , Kiekens Rebecca C M
Published: January 2008

The pregnancy hormone human chorionic gonadotropin (hCG) has been suggested to play an immunoregulatory role in addition to its endocrine function, thus contributing to the prevention of fetal rejection. We hypothesized that hCG is involved in the maternal-fetal immune tolerance by the regulation of dendritic cell (DC) function. Therefore, we studied the effect of hCG on DC maturation. Upon hCG treatment in combination with LPS, mouse bone marrow-derived DC (BMDC) increased the ratio of IL-10:IL-12p70, down-regulated TNF-α, and decreased antigen-specific T cell proliferation. Addition of hCG together with LPS and IFN-γ blocked MHC class II up-regulation, increased IL-10 production, and decreased the antigen-specific T cell proliferation by DC. Splenic DC showed similar results. Upon hCG treatment, IDO mRNA expression and its metabolite kynurenine were increased by LPS- and IFN-γ-stimulated DC, suggesting its involvement in the decreased T cell proliferation. To study the effect of hCG on DC differentiation from precursors, BMDC were generated in the continuous presence of hCG. Under this condition, hCG decreased cytokine production and the induction of T cell proliferation. These data are suggestive for a contribution of hCG to the maternal-fetal tolerance during pregnancy by modifying DC toward a tolerogenic phenotype.
DrosophilaActivin-β and the Activin-like product Dawdle function redundantly to regulate proliferation in the larval brain
Authors: Zhu Changqi C. , Boone Jason Q. , Jensen Philip A. , Hanna Scott , Podemski Lynn , Locke John , Doe Chris Q. , O'Connor Michael B.
Published: January 2008

The Drosophila Activin-like ligands Activin-β and Dawdle control several aspects of neuronal morphogenesis, including mushroom body remodeling, dorsal neuron morphogenesis and motoneuron axon guidance. Here we show that the same two ligands act redundantly through the Activin receptor Babo and its transcriptional mediator Smad2 (Smox), to regulate neuroblast numbers and proliferation rates in the developing larval brain. Blocking this pathway results in the development of larvae with small brains and aberrant photoreceptor axon targeting, and restoring babo function in neuroblasts rescued these mutant phenotypes. These results suggest that the Activin signaling pathway is required for producing the proper number of neurons to enable normal connection of incoming photoreceptor axons to their targets. Furthermore, as the Activin pathway plays a key role in regulating propagation of mouse and human embryonic stem cells, our observation that it also regulates neuroblast numbers and proliferation in Drosophilasuggests that involvement of Activins in controlling stem cell propagation may be a common regulatory feature of this family of TGF-β-type ligands.
Broad-Complex acts downstream of Met in juvenile hormone signaling to coordinate primitive holometabolan metamorphosis
Authors: Konopova Barbora , Jindra Marek
Published: January 2008

Metamorphosis of holometabolous insects, an elaborate change of form between larval, pupal and adult stages, offers an ideal system to study the regulation of morphogenetic processes by hormonal signals. Metamorphosis involves growth and differentiation, tissue remodeling and death, all of which are orchestrated by the morphogenesis-promoting ecdysteroids and the antagonistically acting juvenile hormone (JH), whose presence precludes the metamorphic changes. How target tissues interpret this combinatorial effect of the two hormonal cues is poorly understood, mainly because JH does not prevent larval-pupal transformation in the derived Drosophila model, and because the JH receptor is unknown. We have recently used the red flour beetle Tribolium castaneum to show that JH controls entry to metamorphosis via its putative receptor Methoprene-tolerant (Met). Here, we demonstrate that Met mediates JH effects on the expression of the ecdysteroid-response gene Broad-Complex (BR-C). Using RNAi and a classical mutant, we show that Tribolium BR-C is necessary for differentiation of pupal characters. Furthermore, heterochronic combinations of retarded and accelerated phenotypes caused by impaired BR-C function suggest that besides specifying the pupal fate, BR-C operates as a temporal coordinator of hormonally regulated morphogenetic events across epidermal tissues. Similar results were also obtained when using the lacewing Chrysopa perla (Neuroptera), a member of another holometabolous group with a primitive type of metamorphosis. The tissue coordination role of BR-C may therefore be a part of the Holometabola groundplan.
Influence of shade and irradiation time on the hardness of composite resins
Authors: Della Bona Álvaro , Rosa Vinícius , Cecchetti Dileta
Published: January 2008

This study tested the following hypotheses: 1. increasing light irradiation time (IT) produces greater values of superficial hardness on different depths (0 and 3 mm); and 2. a dark shade composite (A3) needs longer IT than a light shade composite (A1) to produce similar hardness. Disk-shaped specimens (n=24 per shade) were fabricated using a 3-mm-thick increment of composite resin (Z100). Specimens were randomly assigned to 3 groups (n=8) according to the IT (400 mW/cm2) at the upper (U) surface: A1-10 and A3-10: 10 s; A1-20 and A3-20: 20 s; A1-40 and A3-40: 40 s. Specimens were stored in black lightproof containers at 37ºC for 24 h before indentation in a hardness tester. Three Vickers indentations were performed on the U and lower (L) surfaces of each specimen. The indent diagonals were measured and the hardness value calculated. The results were analyzed statistically by ANOVA and Tukey's test (alpha=0.05). Statistically significant differences were found between U and L surfaces of each composite shade-IT combination (p=0.0001) and among the ITs of same shade-surface combination (p=0.0001), except between groups A1-20U and A1-40U, confirming the study hypothesis 1 and partially rejecting the hypothesis 2.
Enfrentamento à violência contra crianças e adolescentes: Projeto Escola que Protege
Authors: Francischini Rosângela , Souza Neto Manoel Onofre de
Published: January 2008

O Estatuto da Criança e do Adolescente especifica que toda criança deverá estar protegida de ações que possam prejudicar seu desenvolvimento. No entanto, a realidade de transgressão a esse direito atinge uma parcela significativa de crianças, que têm seu cotidiano permeado por variadas formas de violência. Com o objetivo de formar profissionais em educação para atuar na defesa dos direitos desses sujeitos a SECAD/MEC, implantou o Projeto Escola que Protege, objeto desta apresentação, considerando que a definição de uma política eficiente no enfretamento da violência passa pelo envolvimento de diversos e estratégicos atores sociais, dentre eles, a comunidade escolar.
Efeito da nutrição da ovelha e do cordeiro sobre o perfil de ácidos graxos do músculo Triceps brachii de cordeiros
Authors: Gallo Sarita Bonagurio , Siqueira Edson Ramos de , Rosa Gilberto Teixeira da
Published: January 2008

O experimento foi realizado com o objetivo de avaliar o efeito da suplementação da ovelha 30 dias antes do parto, da idade à desmama (45 ou 60 dias) dos cordeiros e do sistema de terminação (em confinamento dieta total ou feno) ou a pasto sobre o perfil de ácidos graxos do músculo Triceps brachii de cordeiros machos não-castrados. O animais foram abatidos com 30 kg de peso corporal ou aos 150 dias de idade. Os cordeiros terminados em confinamento alimentados com feno foram abatidos pela idade e os demais pelo peso corporal. Os teores dos ácidos graxos C15:0, C16:0, C17:0, C16:1, C18:1 e C18:3 no músculo diferiram entre os sistemas de terminação dos cordeiros. O músculo dos cordeiros alimentados com dieta completa apresentou maiores valores de C16:0, C16:1 e C18:1, enquanto o músculo daqueles alimentados com feno e em pastagem apresentou maiores teores de C18:3. A dieta alterou o perfil de ácidos graxos no músculo dos cordeiros. A suplementação das ovelhas 30 dias antes do parto e a idade a desmama não afetaram o perfil de ácidos graxos.
Produção de leite e desempenho dos bezerros de vacas Nelore e mestiças
Authors: Oliveira Vítor Corrêa de , Fontes Carlos Augusto de Alencar , Siqueira João Gomes de , Fernandes Alberto Magno , Sant´Ana Nivaldo de Faria , Chambela Neto Alberto
Published: January 2008

O trabalho foi realizado com o objetivo de avaliar as curvas de lactação de vacas Nelore e mestiças F1 Limousin-Nelore (LN) e Simental-Nelore (SN) e o desempenho de suas progênies. Foram utilizadas 13 vacas de cada grupo genético, com 5 a 9 anos de idade, e as suas respectivas crias. A partir do 15º dia após o parto até a desmama dos bezerros (210 dias), as vacas foram mantidas com suas crias em baias individuais. No arraçoamento procurou-se atender 100% das exigências de mantença e lactação das vacas; a mesma ração foi fornecida aos bezerros a partir dos 90 dias de idade visando atender no máximo 30% de suas exigências nutricionais. A ração foi formulada com 30% de concentrado e 70% de silagem, na MS. A produção de leite das vacas foi determinada mensalmente pelo método da diferença de peso dos bezerros. Por meio de um modelo não-linear, estimaram-se o tempo necessário para as vacas atingirem o pico de lactação, a produção no pico, a persistência de produção de leite e as produções total e média diária. As vacas Nelore tiveram, em comparação às mestiças, menores produções no pico de lactação, total e média diária, mas apresentaram maior persistência de lactação. As produções no pico de lactação, total e média diária, nas vacas SN foram maiores que nas vacas LN, no entanto, não houve diferença entre esses grupos quanto à persistência de lactação. Os bezerros das vacas Nelore apresentaram menores ao nascer e à desmama e ganharam menos peso no período de aleitamento em comparação aos de vacas mestiças, que não diferiram entre si. Vacas mestiças têm maior habilidade materna que vacas Nelore.
Three new species of Hyphessobrycon (Characiformes: Characidae) from the upper rio Araguaia basin in Brazil
Authors: Lima Flávio C. T. , Moreira Cristiano R.
Published: January 2008

Three new species of Hyphessobrycon (Characiformes: Characidae) are described from the upper rio Araguaia basin. Hyphessobrycon langeanii n. sp. is distinguished from all congeners by the presence of a well-defined, round humeral spot, a reticulate color pattern, a broad, horizontally-elongate caudal-peduncle blotch, and a relatively wide, faint midlateral dark stripe. Hyphessobrycon eilyos n. sp. is distinguished from all congeners by the absence of humeral and caudal spots; by the presence of numerous dark chromatophores on the lateral surface of the body, intensely concentrated on the ventral region from the pelvic-fin origin to the end of the caudal-fin base, dorsal, adipose, and caudal fins with carmine red pigmentation in life; and the presence of 7-11 maxillary teeth. Hyphessobrycon weitzmanorum n. sp. is distinguished from all congeners by the combination of the possession of two humeral spots and a general dark color pattern. These three new species, along with Creagrutus molinus (Characidae), Apareiodon tigrinus (Parodontidae), Aspidoras velites (Callichthyidae), an undescribed member of the Hypoptopomatinae (Loricariidae), Cnesterodon septentrionalis (Poeciliidae), and Simpsonichthys cholopteryx (Rivulidae), all of which are apparently endemic of the upper rio Araguaia, indicate that this area is a previously unrecognized area of endemism.
Fish assemblages of tropical floodplain lagoons: exploring the role of connectivity in a dry year
Authors: Petry Ana Cristina , Agostinho Angelo Antonio , Gomes Luiz Carlos
Published: January 2008

Irregular rainfall and pronounced reductions of the hydrometric level in the year 2000 resulted in drastically altered hydrological connectivity of lentic environments in the upper Paraná River floodplain. The objective of the present work was to examine spatial and temporal patterns of fish assemblage attributes and structure in relation to limnological variables associated with hydrological connectivity. Fish were collected quarterly by seining in the marginal areas of 15 lagoons belonging to two biotopic categories (connected and disconnected). Variation in assemblage composition reflected the degree of hydrological connectivity. Values of assemblage attributes (species richness, density and biomass) were significantly lower in connected lagoons than in disconnected lagoons. Significantly higher values of species richness and biomass were recorded in November than in August. Rare species had the greatest effect on observed patterns in fish assemblage ordination (DCA). Observed patterns of variation in assemblage attributes were directly correlated with factors related to hydrological connectivity, such as depth, resources (zooplankton and chlorophyll a) and nutrients (total phosphorus).
Macrolevel Stressors, Terrorism, and Mental Health Outcomes: Broadening the Stress Paradigm
Authors: Richman Judith A. , Cloninger Lea , Rospenda Kathleen M.
Published: January 2008

Objectives. We examined the extent to which the stress paradigm linking psychosocial stressors to mental health status has focused disproportionate attention on microlevel social stressors to the detriment of macrolevel stressors. Also, we assessed the effects of the terrorist attacks of September 11, 2001, on subsequent mental health among participants in a Midwestern cohort study.

Methods. Respondents in a 6-wave longitudinal mail survey completed questionnaires before September 11, 2001, and again in 2003 and 2005. Regression analyses focused on measures of negative terrorism-related beliefs and fears, as well as psychological distress and deleterious alcohol use outcomes measured both before and after September 11.

Results. Negative terrorism-related beliefs and fears assessed in 2003 predicted distress and drinking outcomes in 2005 after control for sociodemographic characteristics and pre–September 11 distress and drinking.

Conclusions. The events of September 11 continue to negatively affect the mental health of the American population. Our results support the utility of according greater attention to the effects of such macrolevel social stressors in population studies embracing the stress paradigm.
The Prevalence of Human Papilloma virus Infection in Sinonasal Inverted Papilloma Specimens Classified by Histological Grade
Authors: Kim Jee-Yeon , Yoon Jong-Keun , Citardi Martin J. , Batra Pete S. , Roh Hwan-Jung
Published: January 2008

Background

Histological analysis suggests that inverted papilloma (IP) tumorigenesis may occur through a stepwise series of discrete events. The association between human papilloma virus (HPV) and IP has been described at varying incidences. The purpose of this study was to evaluate the prevalence of the HPV subtypes in a large series of IP specimens classified by histological grade.

Methods

Fifty-seven paraffin-embedded specimens of Korean population were available for study. Each specimen was graded according to a four-stage histological grading system (stages I and II, benign IP; stage III, dysplastic IP; stage IV, carcinoma arising from IP). A representative section of IP specimen was isolated through laser capture microdissection (7.5- to 10-μm laser spot size). Subsequently, DNA extraction and HPV genotyping with the HPV DNA chip test (Biomed Lab Co., Seoul, Korea) was performed. The HPV DNA chip contained 22 type-specific probes that consisted of 15 high-risk subtypes and 7 low-risk subtypes.

Results

Histological grading was as follows: 5, grade I; 23, grade II; 22, grade III; and 7, grade IV. Seven of 57 specimens (12.3%) showed HPV DNA. All of the HPV+ cases showed HPV DNA in early grade (grades I and II) IP lesions. No higher grade (grades III and IV) IP tumors showed HPV DNA. Among the seven HPV+ cases, five were high-risk subtypes and two were unspecified subtypes.

Conclusion

HPV infection, mainly high-risk subtypes, occurs in benign IP as an early event during the multistep tumorigenesis of IP. Cumulative other genetic insults may be required to progress from benign IP (grades I and II) to dysplastic IP (grade III) and carcinoma arising from IP (grade IV).
Bilateral Congenital Choanal Atresia in a 51-Year-Old Woman
Authors: Yasar Husamettin , Ozkul M. Haluk
Published: January 2008

Background

A 51-year-old woman with bilateral congenital choanal atresia (CCA) is presented. She had episodes of respiratory distress that were relieved by crying and worsened by breastfeeding during her newborn period. No other abnormality had been documented during her early childhood period and she had not undergone any surgical intervention or trauma to the nose. No other congenital anomaly was noted.

Methods

The diagnosis was established by endoscopic examination and computed tomography (CT) scan of the paranasal sinuses.

Results

She was treated successfully by a transnasal endoscopic surgical technique with short-term stenting. Follow-up examination 18 months after the surgery still showed patent neochoana.

Conclusion

According to the English literature, this case represents the oldest patient with bilateral CCA presenting for the first time in adult life.
Histological Evaluation of Maxillary Sinus Mucosa after Functional Endoscopic Sinus Surgery
Authors: Anselmo-Lima Wilma T. , Seabra Ferreira Maria Dolores , Pereira Valera Fabiana Cardoso , Rossato Maria , de Mello Valder Rodrigues , Demarco Ricardo Cassiano
Published: January 2008

Background

This study was performed to evaluate the histological changes of the maxillary sinus mucosa of patients with chronic rhinosinusitis (CRS) after functional endoscopic sinus surgery (FESS).

Methods

In a cohort study, biopsy specimens were collected from the maxillary sinus of patients submitted for FESS. One year after surgery, patients were clinically reassessed. Patients showing recurrence of disease (group 1) required a revision surgery, through which a second biopsy specimen was collected. Patients showing a favorable clinical response (group 2) were submitted to an outpatient maxillary biopsy through the previous opened middle meatus antrostomy. Biopsy material from four cadavers was used as control. The histological and electron microscope findings were analyzed.

Results

At the initial surgery, patients presented many histopathological alterations, such as an inflammatory process infiltrating the submucosa, atypical respiratory epithelium with an important increase in goblet cells, metaplasia, or mixed epithelium. Group 1 patients persisted with the same alterations 1 year later, but ciliary dysmorphy was more accentuated. Group 2 patients presented a predominantly pseudostratified epithelium, but some areas contained an increased number of goblet cells and a reduction in the number of ciliated cells.

Conclusion

Recovery of the maxillary sinus mucosa of patients with CRS, observed by electron and light microscopy, was incomplete 1 year after endoscopic surgery, even in nonsymptomatic patients; nevertheless, these alterations were more important in symptomatic patients than in asymptomatic patients.
Efficacy of Cerebrospinal Fluid Fistula Repair: Sensitive Quality Control using the Beta-Trace Protein Test
Authors: Meco Cem , Arrer Erich , Oberascher Gerhard
Published: January 2008

Background

After cerebrospinal fluid (CSF) fistula repair, the goal of watertight sealing may not always be achieved, causing postoperative CSF leakage. The aim of this study was to assess the novel application of the beta-trace protein (betaTP) test for postoperative screening and confirmation of dura repair success.

Methods

Prospectively, we investigated 32 consecutive patients who underwent dura repair. Postoperative nasal secretion and serum were analyzed for CSF marker betaTP, to detect or rule out postoperative CSF leakage.

Results

In 29 patients no CSF was detected, indicating 91% dura repair success after the first step. Three patients required additional surgery, verifying CSF leak. Additional betaTP testing was negative, revealing successful dura repair.

Conclusion

Dura repairs should be controlled for the presence or absence of postoperative CSF leakage. In our hands, the sensitive, fast, and inexpensive betaTP test has shown its value as an effective postoperative screening tool for dura repair success confirmation. Therefore, we consider it as novel “standard of care” and reserve invasive, more expensive or time-consuming methods as second choice.
Rational Modeling of Tertiary Flow for Asphalt Mixtures
Authors: Biligiri Krishna P. , Kaloush Kamil E. , Mamlouk Michael S. , Witczak Matthew W.
Published: January 2008

The objective of this research study was to evaluate several mathematical models to be used in calculating the onset of tertiary flow [referred to as the flow number (FN) parameter] for asphalt mixtures. The FN indicates the onset of shear deformation in asphalt mixtures, which is a significant parameter in evaluating rutting in the field. The FN is obtained from the repeated load permanent deformation (RLPD) laboratory test. Current modeling techniques in determining the FN use a polynomial model fitting approach, which works well for most conventional asphalt mixtures. However, analysis and observations on the use of this polynomial model for rubber-modified asphalt mixtures showed problems in identifying the true FN values. The scope of the work included the collection and analysis of more than 300 RLPD test data files, which comprised more than 40 mixtures, a wide range of test temperatures, and several stress levels. A new comprehensive mathematical model was recommended to accurately determine the FN. The results and analysis were evaluated through manual calculations and found to be accurate, rational, and applicable to all mixture types, whether a tertiary stage was reached or not.
Effect of Binder Type, Aggregate, and Mixture Composition on Fracture Energy of Hot-Mix Asphalt in Cold Climates
Authors: Braham Andrew F. , Buttlar William G. , Marasteanu Mihai O.
Published: January 2008

Detrimental effects of low-temperature cracking of asphalt pavements and overlays have motivated new work in fracture testing of hot-mix asphalt (HMA). Recent work has indicated that the fracture behavior of asphalt concrete at low temperatures can be accurately predicted with a testing and modeling system that, along with viscoelastic bulk material properties, relies simply on fracture energy and material strength. In this study, the disk-shaped compact tension test is used to measure fracture energy of 28 HMA mixtures designed for cold climates. Four parameters are investigated: aggregate type (limestone and granite), temperature (three temperatures, encompassing the Superpave® performance graded binder low temperature grade for each binder tested), asphalt content (Superpave design asphalt content and Superpave design content plus 0.5%), and air voids (4% and 7%). A statistical analysis of results demonstrates the significance for fracture energy of binder content at higher temperatures, aggregate type, and temperature. The air void levels selected and binder content at lower temperatures, however, did not lead to a significant difference in fracture energy. An extrapolation technique is presented that was found to present a rational means for interpreting data from tests that were not finished because of equipment constraints.
Prediction of Fatigue Cracking in Asphalt Pavements
Authors: Molenaar A. A. A.
Published: January 2008

The fatigue performance of asphalt concrete pavements is difficult to predict not only because many of the input parameters needed for the analyses are difficult to obtain but also because the fatigue phenomenon itself is not well understood. Most analyses, for example, take the tensile strain at the bottom of the asphalt layer as the factor that explains fatigue, although many pavements exhibit top-down cracking that has nothing to do with the tensile strain at the bottom of the asphalt layer. This approach implies that calibrating fatigue predictions on the basis of tensile strains at the bottom of the asphalt layer with the amount of cracking observed at the pavement surface is rather unrealistic. Furthermore, it is unlikely that fatigue cracks, if initiated at the bottom of the asphalt layer, show up at the pavement surface as clearly defined cracks. There are many indications that fatigue at the bottom of the asphalt layer is a matter of the development of a deteriorated zone with microcracks rather than development of clearly defined, discrete cracks. It is evident that large shift factors are needed to apply laboratory fatigue relations to field predictions. The magnitude of these shift factors depends, among other determinants, on the type of fatigue test and mode of loading. As discussed in this paper, only the slope of the fatigue relation can be estimated with confidence from laboratory fatigue tests. Finally, this paper shows that the existence of an endurance limit can be debated; in any case it is not a constant value of about 70 μm/m. Experiments have shown that the suggested value is too high.
Pedestrians' Normal Walking Speed and Speed When Crossing a Street
Authors: Montufar Jeannette , Arango Jorge , Porter Michelle , Nakagawa Satoru
Published: January 2008

Walking speed is a key input for various traffic engineering applications. This paper presents the results of research conducted over 18 months to understand the difference between the normal and the crossing walking speeds of pedestrians at signalized intersections and to determine the effect of seasonality on walking speed, taking into account age and gender. For the purposes of this paper, normal walking speed is the speed at which pedestrians walk without needing to cross an intersection, and crossing walking speed is that at which pedestrians walk when they are crossing a signalized intersection. The research found that in all cases the normal walking speed is less than the crossing walking speed. It also found that younger pedestrians walk faster than older pedestrians, regardless of the season and gender, and females walk slower than males, regardless of the season and age. Furthermore, both younger and older pedestrians have a greater normal walking speed in summer than in winter but a lower crossing walking speed in winter than in summer. In addition, the research also found that by use of a design value of 1.2 m/s (4.0 ft/s), as recommended in the current Manual of Uniform Traffic Control Devices, nearly two-thirds of older pedestrians would be excluded in the design process on the basis of their normal walking speed and about 40% would be excluded on the basis of their crossing walking speed. The design value of 1.2 m/s (4.0 ft/s) excludes nearly one-third of younger pedestrians on the basis of their normal walking speed and about 10% on the basis of their crossing walking speed.
Evaluation of Pedestrian and Driver Behaviors at Countdown Pedestrian Signals in Peoria, Illinois
Authors: Schattler Kerrie L. , Wakim Joseph G. , Datta Tapan K. , McAvoy Deborah
Published: January 2008

A study was conducted to assess the effectiveness of countdown pedestrian signals on both pedestrian and motorist behaviors at 13 intersections in Peoria, Illinois. The variables tested in this study included the proportion of pedestrians who started crossing the street during the “Walk,” flashing “Don't Walk,” and steady “Don't Walk” intervals, as well as vehicular positions in the intersection with respect to the traffic signal indication (late in the yellow signal indication and after the red signal indication). A before-and-after study was used at three intersections at which the pedestrian countdown signals were installed. Additionally, five test intersections with countdown pedestrian signals were compared with five control intersections with traditional pedestrian signals. The traffic volumes, geometry, and adjacent land use at the control sites were similar to those at the test sites; however, the control sites did not have the countdown feature. The results of the study indicate that countdown pedestrian signals are effective in enhancing pedestrian safety. No evidence of increased risk-taking behavior of motorists while they were traversing the intersections with countdown pedestrian signals was observed.
Measured Soil Setup of Steel HP Piles from Windsor Bypass Project in North Carolina
Authors: Kim Kyung J. , Kreider Christopher A.
Published: January 2008

Restrikes were performed on piles driven for a North Carolina Department of Transportation highway construction project to verify the required bearing capacity, which was not achieved at the end of initial drive (EOID). Driving records of 98 piles with both initial driving and restrike blow counts and hammer stroke were collected. Six of these piles were driven with a pile-driving analyzer, and Case Pile Wave Analysis Program analysis was performed on the collected pile-driving analyzer data. All piles were steel H-pile piles, and the restrikes were done within 144 h after the EOID. The pile bearing capacities of both EOID and restrike were estimated from the blow counts and hammer stroke using the GRL Engineers Inc. Wave Equation Analysis Program, Version 2005. Soil setup ratios of these piles were computed and statistically analyzed to find a reliable setup ratio that can be applied to the bearing capacity obtained at the EOID of the remaining piles in this project to ensure the required bearing without a restrike. The mean soil setup ratio of all piles in this project was estimated at 1.41. However, no setup ratio can be applied to the EOID bearing capacity of an individual pile with a 98% confidence level. Restrike of every pile is required to ensure this level of confidence. A setup ratio of 1.10 can be applied with a 90% confidence level. The setup ratios vary greatly from pile to pile. Soil setup occurs rapidly after EOID in this project. Soil setup is more significant in loose or soft soils than in dense or stiff soils.
Laboratory Investigation of Behavior of Foundations on Geosynthetic-Reinforced Clayey Soil
Authors: Chen Qiming , Abu-Farsakh Murad Y. , Sharma Radhey , Zhang Xiong
Published: January 2008

The behavior of foundations on geosynthetic-reinforced clayey soil of low to medium plasticity using laboratory model footing tests was investigated. The model footing was made of a steel plate with dimensions of 152 mm (6 in.) × 152 mm (6 in.). The parameters investigated in this study included the top layer spacing, the number of reinforcement layers, the vertical spacing between layers, and the stiffness and type of reinforcement. The effect of reinforcement on the vertical stress distribution in the clay and the strain distribution along the reinforcement were also investigated. The test results showed that the inclusion of reinforcement could significantly improve the soil's bearing capacity and reduce the footing settlement. With three or more layers of reinforcement, the settlement could be reduced by approximately 50% at a relatively medium surface pressure. The geogrids with higher stiffness performed better than geogrids with lower stiffness. The test results also showed that the induced vertical stresses in clay under the center of footing could be appreciably reduced with the inclusion of reinforcement, which would result in reducing the consolidation settlement. Insignificant strain measured in the geogrid beyond its effective length of 6.0B (where B is the footing width) indicated that the geogrid beyond this length provided negligible reinforcement effect.
Guidelines for Using Geosynthetics with Hot-Mix Asphalt Overlays to Reduce Reflective Cracking
Authors: Button Joe W. , Lytton Robert L.
Published: January 2008

This paper provides complete guidelines for using geosynthetics with hot-mix asphalt overlays to reduce reflective cracking. Definitions of the various types of geosynthetics that are commercially available along with some of their advantages and disadvantages are also provided. These guidelines address the following: when to consider a geosynthetic product, how to select and store geosynthetics, cost considerations, pavement design with a geosynthetic, overlay construction with a geosynthetic, construction inspection, and potential construction problems.
Forwardcalculation of Pavement Moduli with Load-Deflection Data
Authors: Stubstad Richard , Jiang Y. Jane , Lukanen Erland
Published: January 2008

A new approach has been developed for determining layered elastic moduli from in situ load-deflection data. This approach is called forwardcalculation, and it differs from backcalculation in that modulus values are calculated directly from the load-deflection data by using closed-form formulas rather than through iteration. The closed-form equations are used for the subgrade and the bound surface course for both flexible and rigid pavement systems. Intermediate-layer moduli are estimated through commonly used modular ratios between adjacent layers. The entire pre-1998 Long-Term Pavement Performance (LTPP) set of backcalculated results was screened with forwardcalculated moduli. Because both back-and forwardcalculation techniques use identical falling weight deflectometer load-deflection data as input, it was expected that the moduli derived from each approach should be reasonably close to each other. This result was not always the case, however. Forwardcalculated values were, in most cases, more stable on a section-by-section basis than the backcalculated values in the LTPP database. Similarly, the forwardcalculated values usually appeared more reasonable. The exception to this finding was the portion of the database based on slab-on-dense-liquid or slab-on-elastic-solid theory, in which the correspondence between the two approaches was excellent, and both approaches were stable.
Evaluation of New Mechanistic–Empirical Pavement Design Guide Rutting Models for Multiple-Axle Loads
Authors: Salama Hassan K. , Haider Syed Waqar , Chatti Karim
Published: January 2008

The new FHWA Mechanistic–Empirical Pavement Design Guide (M-E PDG) does away with the AASHO-derived concept of the equivalent single-axle load and calculates damage caused by various axle configurations directly. Because multiple axles represent about half the axle configurations that the pavement will experience, there is a need to evaluate the M-E PDG procedure for predicting rutting due to multiple-axle configurations. Axle factors (AFs) based on rutting were calculated for different axle configurations by using three procedures: the M-E PDG, accounting for the effect of each individual axle within a group, and integrating the entire strain pulse. The AFs from these procedures were compared with laboratory-derived values for asphalt concrete. Also, layer rutting contributions were predicted for six in-service SPS-1 experiment sections from the Long-Term Pavement Performance Program with the M-E PDG software and were compared with the analysis of their transverse surface profiles. The results show that the M-E PDG procedure underestimates rutting prediction due to multiple axles. Calibration of the M-E PDG rut models with field data seems to improve their prediction, although it is still lower than expected for multiple axles. The best method for calculating rut depths under multiple axles appears to be integration of the entire strain pulse. This method shows that rutting damage is proportional to the number of axles within an axle group. This theory was confirmed in the laboratory for asphalt concrete. Also, although the M-E PDG rut models are superior to previous rut models, in that they are able to dissect the total surface rutting between all pavement layers, their prediction of the individual layer rutting contributions does not always agree with results from the analysis of measured transverse profiles.
Simulation of Urban Rail Operations
Authors: Koutsopoulos Haris N. , Wang Zhigao
Published: January 2008

Simulation models of urban rail operations are valuable tools for analysis of the operations of complex rail transit systems. A framework is presented for the application of rail simulation that includes calibration, validation, evaluation methodology, and interpretation of results. Methods that can be used at each step to facilitate the application are discussed. In particular, approaches are presented for calibration of model parameters and inputs, such as dynamic arrival and alighting rates at stations. Application of simulation tools can be greatly enhanced by the use of train circuit occupancy data collected by automated control systems. A new rail simulation model, SimMetro, specifically designed for service performance analysis taking into account the major sources of uncertainty in operations, is also presented. A case study is used to illustrate the applicability of the proposed framework in testing alternative real-time control strategies.
Probabilistic Forecasts for Aviation Traffic at FAA's Commercial Terminals
Authors: Bhadra Dipasis , Schaufele Roger
Published: January 2008

Forecasting air travel in uncertain times is a challenging task. The effects of uncertainties accompanied with usual errors emanating from estimation of demand prevent deterministic forecasts from representing an uncertain future. The framework that is presented takes into account uncertainty for which the nature and sources are unknown. A parametric distribution fitting the past growth rates captures the probabilities associated with the outcomes representing the future uncertainty at the airports. This process combined with Monte Carlo simulation is used to generate probabilistic forecasts at the top 50 commercial airports in the United States. The methodology is illustrated by using Hartsfield–Jackson Atlanta International Airport in Georgia. Probabilistic forecasts provide an important tool for investment and personnel planning in uncertain times.
Analysis of Survey Data on Situation Awareness of Helicopter Pilots
Authors: Lee Yeong Heok , Choi Youn Chul , Choi Sung Ho , Ujimoto K. Victor
Published: January 2008

According to the U.S. National Transportation Safety Board, from 1989 to 1992, situation awareness (SA) was a major factor causing 80% of all aircraft accidents in scheduled airlines. Therefore, the prevention of accidents through effective training in SA became a pivot in aviation safety. During the past 10 years, since all helicopter accidents in South Korea were caused by factors related to SA, an appropriate counter-measure was required. A study used survey data to examine various factors related to SA that could affect helicopter pilots. Recognition of and countermeasures for those factors in emergency situations were analyzed. The results show that although factors associated with SA and vigilance have lower correlations with each other, factors associated with recognition, diagnosis, and generation and implementation of solutions have higher correlations with each other. Thus, the results demonstrate the need for better SA through educational training. Also, there were no significant differences among factors related to proficiency, procedure, acquaintance, anticipation, and comprehension between instructor pilots and copilots. However, there were significant differences regarding mentality, position information, experience, and preparation. These results highlight the differences between instructor pilots and copilots derived from the acquisition of knowledge and flying experience.
New Generation of Wide-Base Tires
Authors: Al-Qadi Imad L. , Elseifi Mostafa A.
Published: January 2008

Since the new generation of wide-base tires was introduced in 2000, researchers from a variety of disciplines have evaluated the impact of the new tires on trucking operations, road infrastructure, and the environment. This paper outlines the status of wide-base tire technology with respect to established benefits, concerns to be addressed, and the potential use of this product in trucking operations. The objective of this paper is to serve as a benchmark for researchers and truck fleet managers with respect to the use of this new technology during the gradual transition from dual tires to the new generation of wide-base tires. For trucking operations, the new generation of wide-base tires provides substantial benefits in fuel efficiency, hauling capacity, tire cost and repair, ride, comfort, and vehicle stability. The new generation of wide-base tires is also comparable to conventional dual-tire assemblies in truck operation and safety. Since the new generation of wide-base tires has only been on the market for a short period of time, the potential for recapping these tires is not well-documented. As for environmental impact, the new generation of wide-base tires provides substantial benefits in gas emission reduction, noise reduction, and tire recycling at the end of service life. With respect to pavement and for primary road applications, pavement damage similar to damage rendered by conventional dual tires is expected, given that the probability of fatigue cracking is usually low in these pavement classes.
Monitoring Displays Coupled with Speed Cameras
Authors: Woo T. Hugh , Ho Shih-Ming , Chen Hung-Lin
Published: January 2008

Speeding is a common behavior of drivers all over the world. Traditional speed-controlling measures fail to reduce speeding effectively. With advances in technology, new devices have been developed for such a purpose, including a speed-monitoring display (SMD) that detects the speed of vehicles and displays it on an electronic board, informing drivers of their current speed. It has been hypothesized that SMDs coupled with speed cameras to catch violators may deter drivers from speeding. This study examined the effectiveness of SMDs with enforcement cameras on speed reduction. Speed data of free-flowing vehicles were collected before and after the SMD and enforcement cameras were installed. Speed data were also collected with the SMD turned off and then on again. The results showed that mean speeds of vehicles were significantly reduced after SMD and camera installation. Even with the SMD turned off, the speed reduction was not significantly affected, but the proportion of speeding vehicles became higher. It was found that the presence of SMDs could alert drivers of enforcement cameras downstream, making speeders adjust their speed to comply with the limit.
Evaluation of Intersection Safety Camera Program in Edmonton, Canada
Authors: Sayed Tarek , de Leur Paul
Published: January 2008

Enforcing traffic signal compliance in urban areas can be a difficult task, as the process is often limited by police resources and by traditional enforcement methods. Therefore, conventional traffic enforcement should be supplemented with advanced technologies, such as intersection safety cameras. Intersection safety cameras, often referred to as red light cameras (RLCs), are being used increasingly to help communities enforce against deliberate red light running. Since the 1970s, Europe, Australia, and North America have been using photo enforcement technology to improve safety at intersections. The City of Edmonton, Canada, has used automated photo enforcement as part of the overall traffic enforcement activity. The Intersection Safety Camera Program started as a pilot project in 1998, which quickly expanded into a comprehensive program for the entire city. Because a significant period had elapsed since the inception of the program, the Edmonton Police Commission wanted a study to determine the overall safety effect of the photo enforcement program. This paper describes the evaluation of Edmonton's Intersection Safety Camera (ISC) program. The paper describes the methodology used in the evaluation, the data collection–compilation effort required for the evaluation, and, finally, the results of the program measured in relation to reducing the number of collisions at the intersections that were treated with photo enforcement cameras. Also included is a summary of the literature associated with the deployment of RLCs.