bluuebunny/crossref_metadata_2025 huggingface dataset:
Structural alterations in the seminiferous tubules of rats treated with immunosuppressor tacrolimus
Authors: Caneguim Breno H , Cerri Paulo S , Spolidório Luís C , Miraglia Sandra M , Sasso-Cerri Estela
Published: February 2009

Background

Tacrolimus (FK-506) is an immunosuppressant that binds to a specific immunophilin, resulting in the suppression of the cellular immune response during transplant rejection. Except for some alterations in the spermatozoa, testicular morphological alterations have not been described in rats treated with tacrolimus. In the present study, we purpose to evaluate if the treatment with tacrolimus at long term of follow-up interferes in the integrity of the seminiferous tubules.

Methods

Rats aging 42-day-old received daily subcutaneous injections of 1 mg/kg/day of tacrolimus during 30 (T-30) and 60 (T-60) days; the rats from control groups (C-30 and C-60) received saline solution. The left testes were fixed in 4% formaldehyde and embedded in glycol methacrylate for morphological and morphometric analyses while right testes were fixed in Bouin's liquid and embedded in paraffin for detection of cell death by the TUNEL method. The epithelial and total tubular areas as well as the stages of the seminiferous epithelium and the number of spermatocytes, spermatids and Sertoli cells (SC) per tubule were obtained.

Results

In the treated groups, seminiferous tubules irregularly outlined showed disarranged cellular layers and loss of germ cells probably due to cell death, which was revealed by TUNEL method. In addition to germ cells, structural alterations in the SC and folding of the peritubular tissue were usually observed. The morphometric results revealed significant decrease in the number of SC, spermatocytes, spermatids and significant reduction in the epithelial and total tubular areas.

Conclusion

Tacrolimus induces significant histopathological disorders in the seminiferous tubules, resulting in spermatogenic damage and reduction in the number of Sertoli cells. A careful evaluation of the peritubular components will be necessary to clarify if these alterations are related to the effect of FK-506 on the peritubular tissue.
Video-assisted thoracic surgery (VATS) as a safe alternative for the resection of pulmonary metastases: a retrospective cohort study
Authors: Carballo Marilee , Maish Mary S. , Jaroszewski Dawn E. , Holmes Carmack E.
Published: February 2009

Background

VATS has become a preferred method for benign surgical conditions, yet still remains controversial for malignancies. The purpose of this study was to review our results of pulmonary metastasectomies using both conventional open thoracotomy and VATS techniques.

Methods

This is a retrospective chart review of pulmonary metastasectomies performed from 1986 to 2006. The surgical approach used for the initial pulmonary metastasectomy was either open thoracotomy or VATS. Main outcomes were overall survival and recurrence free survival, evaluated using Kaplan Meier analysis. A non-inferiority margin was set at 0.2.

Results

A total of 280 surgical procedures were performed on 186 patients. From 171 eligible individuals, 135 patients were treated with thoracotomy (82 M, 53 F; median age 49 years), and 36 with VATS (18 M, 18 F; median age 58.5 years). Primary cancers were mainly: 81 sarcoma (47%), 26 colorectal adenocarcinoma (15%) and 22 renal cell carcinoma (13%). Median postoperative follow was 26.2 months. The conversion rate was 10.3% and there were no cases of pleural cavity seeding. The 5-year overall survival rates were 58.8% for thoracotomy and 69.6% for VATS, with median overall survival of 53.2 months and 30.1 months, respectively (p = 0.03). The estimated difference in 5-year overall survival was 10.8%. Second occurrences were noted in 59 thoracotomy and 10 VATS patients. The 5-year recurrence free survival rates were 51% in thoracotomy and 67% in VATS (p = 0.27), with median recurrence free survival of 24.8 months and 25.6 months, respectively.

Conclusion

In cases of pulmonary metastases, VATS is an acceptable alternative that is both safe and efficacious. Non-inferiority analysis of 5-year overall survival demonstrates that VATS is equivalent to thoracotomy. VATS patients also have a longer recurrence free survival. Based on our experience, it is permissible to use VATS resection in these circumstances: small tumor, fewer nodules, single lesion, age ≤ 53, unilateral, tumor size amenable to wedge resection, and non-recurrent disease.
Cost-utility analysis of palivizumab in Italy: results from a simulation model in the prophylaxis of respiratory syncytial virus infection (RSV) among high-risk preterm infants
Authors: Chirico Gaetano , Ravasio Roberto , Sbarigia Urbano
Published: February 2009

Introduction

The aim of this study was to assess the cost-utility of palivizumab versus no prophylaxis in the prevention of respiratory syncytial virus infection among high-risk preterm infants.

Methods

We used and adapted a pre-existent model in which two cohorts of patients received palivizumab or no prophylaxis. The patients were followed for their expected lifetimes. The economic evaluation was conducted from the perspective of the Italian National Health Service. We considered Life-Years Gained (LYGs), Quality-Adjusted Life-Years (QALYs) and direct medical costs (pharmacological treatment, hospitalization, recurrences for wheezing, etc.). LYGs and QALYs were based on the results of a double blind cohort study with prospective follow-up and direct medical costs were based on Italian treatment patterns. Benefits and costs were discounted at 3%. Costs were assessed in 2007 Euros. Sensitivity and threshold analysis on key clinical and economic parameters were performed.

Result

For the two cohorts, the expected life-years (per patient) with palivizumab versus no prophylaxis were 29.842 and 29.754 years, respectively. Quality-adjusted life years (per patient) with palivizumab were 29.202, and for no prophylaxis were 29.043. The expected cost (per patient) was € 6,244.20 with palivizumab and € 4,867.70 with no prophylaxis. We calculated for palivizumab versus no prophylaxis the incremental cost per LYG and per QALY gained. It was € 15,568.65 and € 8,676.74, respectively.

Conclusion

This study suggests that, compared with no prophylaxis, palivizumab is cost-effective in the prevention of respiratory syncytial virus infection among high risk preterm infants.
High frequency of BRCA1, but not CHEK2 or NBS1 (NBN), founder mutations in Russian ovarian cancer patients
Authors: Suspitsin Evgeny N , Sherina Nathalia Yu , Ponomariova Daria N , Sokolenko Anna P , Iyevleva Aglaya G , Gorodnova Tatyana V , Zaitseva Olga A , Yatsuk Olga S , Togo Alexandr V , Tkachenko Nathalia N , Shiyanov Grigory A , Lobeiko Oksana S , Krylova Nadezhda Yu , Matsko Dmitry E , Maximov Sergey Ya , Urmancheyeva Adel F , Porhanova Nathalia V , Imyanitov Evgeny N
Published: February 2009

Background

A significant portion of ovarian cancer (OC) cases is caused by germ-line mutations in BRCA1 or BRCA2 genes. BRCA testing is cheap in populations with founder effect and therefore recommended for all patients with OC diagnosis. Recurrent mutations constitute the vast majority of BRCA defects in Russia, however their impact in OC morbidity has not been yet systematically studied. Furthermore, Russian population is characterized by a relatively high frequency of CHEK2 and NBS1 (NBN) heterozygotes, but it remains unclear whether these two genes contribute to the OC risk.

Methods

The study included 354 OC patients from 2 distinct, geographically remote regions (290 from North-Western Russia (St.-Petersburg) and 64 from the south of the country (Krasnodar)). DNA samples were tested by allele-specific PCR for the presence of 8 founder mutations (BRCA1 5382insC, BRCA1 4153delA, BRCA1 185delAG, BRCA1 300T>G, BRCA2 6174delT, CHEK2 1100delC, CHEK2 IVS2+1G>A, NBS1 657del5). In addition, literature data on the occurrence of BRCA1, BRCA2, CHEK2 and NBS1 mutations in non-selected ovarian cancer patients were reviewed.

Results

BRCA1 5382insC allele was detected in 28/290 (9.7%) OC cases from the North-West and 11/64 (17.2%) OC patients from the South of Russia. In addition, 4 BRCA1 185delAG, 2 BRCA1 4153delA, 1 BRCA2 6174delT, 2 CHEK2 1100delC and 1 NBS1 657del5 mutation were detected. 1 patient from Krasnodar was heterozygous for both BRCA1 5382insC and NBS1 657del5 variants.

Conclusion

Founder BRCA1 mutations, especially BRCA1 5382insC variant, are responsible for substantial share of OC morbidity in Russia, therefore DNA testing has to be considered for every OC patient of Russian origin. Taken together with literature data, this study does not support the contribution of CHEK2 in OC risk, while the role of NBS1 heterozygosity may require further clarification.
Protein kinase D1 regulates matrix metalloproteinase expression and inhibits breast cancer cell invasion
Authors: Eiseler Tim , Döppler Heike , Yan Irene K , Goodison Steve , Storz Peter
Published: February 2009

Introduction

The biological and molecular events that regulate the invasiveness of breast tumour cells need to be further revealed to develop effective therapies that stop breast cancer from expanding and metastasising.

Methods

Human tissue samples of invasive breast cancer and normal breast, as well as breast cancer cell lines, were evaluated for protein kinase D (PKD) expression, to test if altered expression could serve as a marker for invasive breast cancer. We further utilised specific PKD1-shRNA and a system to inducibly-express PKD1 to analyse the role of PKD1 in the invasive behaviour of breast cancer cell lines in two-dimensional (2D) and three-dimensional (3D) culture. Invasive behaviour in breast cancer cell lines has been linked to matrix metalloproteinases (MMPs), so we also determined if PKD1 regulates the expression and activity of these enzymes.

Results

We found that the serine/threonine kinase, PKD1, is highly expressed in ductal epithelial cells of normal human breast tissue, but is reduced in its expression in more than 95% of all analysed samples of human invasive breast tumours. Additionally, PKD1 is not expressed in highly invasive breast cancer cell lines, whereas non-invasive or very low-invasive breast cancer cell lines express PKD1. Our results further implicate that in MDA-MB-231 cells PKD1 expression is blocked by epigenetic silencing via DNA methylation. The re-expression of constitutively-active PKD1 in MDA-MB-231 cells drastically reduced their ability to invade in 2D and 3D cell culture. Moreover, MCF-7 cells acquired the ability to invade in 2D and 3D cell culture when PKD1 expression was knocked-down by shRNA. PKD1 also regulated the expression of breast cancer cell MMPs, MMP-2, MMP-7, MMP-9, MMP-10, MMP-11, MMP-13, MMP-14 and MMP-15, providing a potential mechanism for PKD1 mediation of the invasive phenotype.

Conclusions

Our results identify decreased expression of the PKD1 as a marker for invasive breast cancer. They further suggest that the loss of PKD1 expression increases the malignant potential of breast cancer cells. This may be due to the function of PKD1 as a negative regulator of MMP expression. Our data suggest re-expression of PKD1 as a potential therapeutic strategy.
SEPALLATA3: the 'glue' for MADS box transcription factor complex formation
Authors: Immink Richard GH , Tonaco Isabella AN , de Folter Stefan , Shchennikova Anna , van Dijk Aalt DJ , Busscher-Lange Jacqueline , Borst Jan W , Angenent Gerco C
Published: February 2009

Background

Plant MADS box proteins play important roles in a plethora of developmental processes. In order to regulate specific sets of target genes, MADS box proteins dimerize and are thought to assemble into multimeric complexes. In this study a large-scale yeast three-hybrid screen is utilized to provide insight into the higher-order complex formation capacity of the Arabidopsis MADS box family. SEPALLATA3 (SEP3) has been shown to mediate complex formation and, therefore, special attention is paid to this factor in this study.

Results

In total, 106 multimeric complexes were identified; in more than half of these at least one SEP protein was present. Besides the known complexes involved in determining floral organ identity, various complexes consisting of combinations of proteins known to play a role in floral organ identity specification, and flowering time determination were discovered. The capacity to form this latter type of complex suggests that homeotic factors play essential roles in down-regulation of the MADS box genes involved in floral timing in the flower via negative auto-regulatory loops. Furthermore, various novel complexes were identified that may be important for the direct regulation of the floral transition process. A subsequent detailed analysis of the APETALA3, PISTILLATA, and SEP3 proteins in living plant cells suggests the formation of a multimeric complex in vivo.

Conclusions

Overall, these results provide strong indications that higher-order complex formation is a general and essential molecular mechanism for plant MADS box protein functioning and attribute a pivotal role to the SEP3 'glue' protein in mediating multimerization.
NOD2/CARD15 on bone marrow CD34+ hematopoietic cells mediates induction of cytokines and cell differentiation
Authors: Sioud Mouldy , Fløisand Yngvar
Published: February 2009

Human bone marrow (BM) hematopoietic cells were found recently to express functional TLRs and TLR signaling-induced cytokine production and cell differentiation. Here, we have asked whether signals other than those from TLRs could instruct BM CD34+ cells to produce cytokines and differentiate by uncovering the role of nucleotide oligomerization domain (Nod)-like receptor (NLR) family members, NOD1 and NOD2. We show that NOD2 is expressed by freshly isolated human BM CD34+ cells, whereas the expression of its close homologue NOD1 is very weak. Stimulation of the cells by the muramyl dipeptide (MDP), but not its inactive D–D enantiomer, is sufficient to trigger the expression of TNF-α, GM-CSF, CD11c, CD14, CD206, and the transcription factor PU.1, which is indispensable for cell differentiation toward the myeloid lineage. MDP differentiated CD11c+ cell subset-activated T cells in MLR. Furthermore, NOD2 stimulation enhanced the CD34+ response to TLR ligands (e.g., LPS, palmitoyl-3-cysteine-serine-lysine-4) and increased intracellular α-defensin protein levels. Although the best-known function of NLRs involves mature cells, our data highlight for the first time the functionality of these receptors in human BM CD34+ hematopoietic cells.
Flagellar membrane localization via association with lipid rafts
Authors: Tyler Kevin M. , Fridberg Alina , Toriello Krista M. , Olson Cheryl L. , Cieslak John A. , Hazlett Theodore L. , Engman David M.
Published: February 2009

The eukaryotic flagellar membrane has a distinct composition from other domains of the plasmalemma. Our work shows that the specialized composition of the trypanosome flagellar membrane reflects increased concentrations of sterols and saturated fatty acids, correlating with direct observation of high liquid order by laurdan fluorescence microscopy. These findings indicate that the trypanosome flagellar membrane possesses high concentrations of lipid rafts: discrete regions of lateral heterogeneity in plasma membranes that serve to sequester and organize specialized protein complexes. Consistent with this, a dually acylated Ca2+ sensor that is concentrated in the flagellum is found in detergent-resistant membranes and mislocalizes if the lipid rafts are disrupted. Detergent-extracted cells have discrete membrane patches localized on the surface of the flagellar axoneme, suggestive of intraflagellar transport particles. Together, these results provide biophysical and biochemical evidence to indicate that lipid rafts are enriched in the trypanosome flagellar membrane, providing a unique mechanism for flagellar protein localization and illustrating a novel means by which specialized cellular functions may be partitioned to discrete membrane domains.
A novel role for SED1 (MFG-E8) in maintaining the integrity of the epididymal epithelium
Authors: Raymond Adam S. , Shur Barry D.
Published: February 2009

The epididymis is a highly convoluted tubule that connects the testis with the vas deferens, and in which mammalian sperm acquire the ability to fertilize eggs. The most proximal portion of the epididymis, or initial segment, secretes numerous factors that are critical for sperm maturation and storage. One such factor is SED1 (also known as MFG-E8) a bi-motif protein composed of two N-terminal EGF domains, the second of which contains an RGD motif, and two C-terminal discoidin domains (also known as F5/8 type C domains). Previous studies have reported that SED1 is secreted into the epididymal lumen, where it coats sperm and later facilitates sperm-egg binding. Herein, we report that SED1-null males also harbor unexpected epididymal pathologies, including detached epithelia and spermatic granulomas. We therefore examined whether SED1 has a tissue-intrinsic role in the epididymis, in addition to its role in sperm-egg adhesion. Improved fixation protocols revealed that SED1 is found in the basolateral domains of epididymal epithelial cells in vivo, and similarly, SED1 is secreted both apically and basally from polarized epididymal cells in vitro. The basolateral distribution of SED1 suggests that it may play a novel role in epididymal cell adhesion. Consistent with this, in vitro assays showed that SED1 supports epididymal cell adhesion via RGD binding to αV integrin receptors on epididymal epithelial cells. Finally, epididymal cells from SED1-null males showed reduced adhesion in vitro, a phenotype that can be rescued with exogenous SED1. These results suggest that SED1 facilitates epididymal cell adhesion, and that its loss leads to breakdown of the epididymal epithelium and consequent development of spermatic granulomas.
Prediction of Punching Shear Failure Behaviour of Slab-Edge Column Connections with Varying Opening and Column Parameters
Authors: Guan Hong
Published: February 2009

A numerical analysis using the non-linear Layered Finite Element Method (LFEM) is undertaken to predict the effect of openings on punching shear failure behaviour of slab-column connections with shear stud reinforcement (SSR). In all, twenty one (21) models are examined through six parametric studies including varying the opening size and location and varying the column aspect ratio. The numerical results covering the load-deflection response, ultimate shear strength, deformation and crack pattern are evaluated in some detail. Where applicable the predicted ultimate shear strengths are compared to the experimental results. Also included in the comparison are the empirical predictions recommended by the Standards Association of Australia and the American Concrete Institute. This investigation is an important step towards the determination of the size and location of opening and the size of column for optimum structural performance of flat plate systems.
Bridge-Weigh-In-Motion by Two-Span Continuous Bridge with Skew and Heavy-Truck Flow in Fukuoka Area, Japan
Authors: Yamaguchi Eiki , Kawamura Shin-Ichi , Matuso Kazushi , Matsuki Yuta , Naito Yasushi
Published: February 2009

For clarifying maintenance requirements of National Highway 201 in the Fukuoka area, a project to investigate actual truck weights was initiated in the year 2002. To this end, the bridge-weigh-in-motion was employed. Nevertheless, a two-span continuous curved bridge with skew was the only bridge available in the area: the bridge is far from ideal for the weigh-in-motion. Preliminary field test taking account of various traffic situations was therefore conducted carefully to see if the project goal could be achieved with this bridge. The test result has confirmed that the bridge-weigh-in-motion employed in the present project can estimate truck weights with satisfactory accuracy, the error being 11.7% at most. The real-time weigh-in-motion system was then constructed and run for 237 days in the year 2004. The data thus obtained reveals characteristics of heavy-truck flow in National Highway 201 in the Fukuoka area.
Numerical Simulations of Nonlinear Seismic Torsional Pounding between Two Single-Story Structures
Authors: Wang L.X. , Chau K.T. , Wei X.X.
Published: February 2009

Nonlinear seismic torsional poundings between two asymmetric single-story structures are investigated numerically. The torsional vibrations of these structures are modeled by 2 translational displacements and 1 rotation, and the impact force is modeled by the nonlinear but frictionless Hertz contact. Thirteen pounding scenarios are used to check for impact occurrence during the numerical integration. Inclusion of torsional response leads to more chaotic responses, comparing to the translational poundings considered by Chau and Wei (2001). For certain excitation periods, numerical simulations result in periodic group poundings that have been reported experimentally by Chau et al. (2003), and these periodic group poundings do not exist for the cases of non-torsional poundings. When the separation distance between the two structures increases, the chance of poundings decreases but the magnitude and shape of the relative impact velocity spectrum remain roughly the same. In general, relative impact velocity decreases with the translational damping ratio, but is less sensitive to the torsional damping ratio and to the value of eccentricity.
Knowledge Acquisition in Parametric Model Development
Authors: Hudson Roly
Published: February 2009

This paper addresses the development of parametric models in contemporary architectural practice. A parametric model can be regarded as a representation of a solution space and in order to structure this, a description of the problem is required. Architectural design tasks are typically ill structured, the goals may not be defined and the means unknown. Moving from an incomplete problem description to a functional parametric model is a difficult task. This paper aims to demonstrate that through a combination of knowledge acquisition and capture a parametric model can develop from an incomplete problem description. This demonstration draws on existing strands of design theory which are then used to outline a theoretical framework. This framework is then used to examine a case study of a live project and practical examples of the described theory in action are given. The practical observations are the result of a case study involving the author as a participant and observer working with HOK Sport to develop a cladding geometry solution for Lansdowne Road Stadium in Dublin.
From Concept to Reality: Digital Systems in Architectural Design and Fabrication
Authors: Larsen Knut Einar , Schindler Christoph
Published: February 2009

One of the challenges for today's architectural designers is the establishment of continuous digital processes between design and fabrication. To achieve this, designers need to acquire knowledge about the production and the methods and tools involved. Two case studies organized at the Norwegian University of Science and Technology (NTNU) on digital timber fabrication investigate the new field of collaboration between architectural designers and fabricators. The studies demonstrate the design potential of acquiring insights into the fabricators' software and digital production machinery and reflect contemporary fabrication technology in formal expression. We identified two different approaches to formal exploration that we defined as “sophistication of the detail” and “variation of the element”.
Model‐related factor score predictors for confirmatory factor analysis
Authors: Beauducel André , Rabe Sirko
Published: February 2009

The present paper introduces model‐related (MR) factor score predictors, which reflect specific aspects of confirmatory factor models. The development is mainly based on Schönemann and Steiger's regression score components, but it can also be applied to the factor score coefficients. It is shown that the rotation of factor score predictors has no impact on the covariance matrix reproduced from the corresponding regression component patterns. Thus, regression score components or factor score coefficients can be rotated in order to obtain the required properties. This idea is the basis for MR factor score predictors, which are computed by means of a partial Procrustes rotation towards a target pattern representing the interesting properties of a confirmatory factor model. Two examples demonstrate the construction of MR factor score predictors reflecting specific constraints of a factor model.
Does switching between strategies within the same task involve a cost?
Authors: Luwel Koen , Schillemans Viki , Onghena Patrick , Verschaffel Lieven
Published: February 2009

In two experiments, participants had to switch regularly between two cognitive strategies of a different complexity in the context of a numerosity judgement task. Expt 1 comprised bivalent stimuli (i.e. allowing the application of the two strategies), whereas Expt 2 involved univalent stimuli (i.e. allowing the application of only one strategy). Both experiments revealed that switching between strategies entailed a cognitive cost that was reflected in longer response times on switch compared to non‐switch trials but not in reduced accuracy. The size of this switch cost did not differ as a function of strategy complexity but tended to diminish as a strategy became more appropriate for solving a particular problem. We discuss the extent to which current theories of task switching can account for these findings.
Does colour preference have a role in colour term acquisition?
Authors: Pitchford Nicola J. , Davis Emma E. , Scerif Gaia
Published: February 2009

A developmental association exists between colour preference and emerging colour term acquisition in young children. Colour preference might influence colour term acquisition by directing attention towards or away from a particular colour, making it more or less memorable. To investigate the role that colour preference may have in the acquisition of colour terms, experimental tasks of colour preference, discrimination, attention, memory, and new colour term learning, were given to three groups of participants (preschool children; primary school children; and adults). Each task utilized the same colour stimuli, which were four computer‐simulated colours, matched perceptually to four different Munsell chips, drawn from the same colour category. Three colours varied systematically from an anchor colour (10PB 4/8) only in saturation (10PB 4/4), luminance (10PB 6/8), or hue (5P 4/8). Results showed that within‐category colour preferences emerged with age, and that when established within individuals, most preferred colours were named significantly more accurately than least preferred colours, although this association did not appear to be mediated directly by attention or memory. Rather, perceptual saliency was shown to have a mediating role, to some extent, in determining the relationship between colour preference and the cognitive processing of colour.
Simulation (mostly) rules: A commentary
Authors: Harris Paul L.
Published: February 2009

I consider three issues: children's attribution of belief‐based emotions, the contribution of language input to children's developing theory of mind, and the default settings we assume in our dealings with the world. I ask whether the proposals made by Mitchell, Currie and Ziegler can help throw light on each issue (Mitchell, Currie, & Ziegler, 2009).
CBR Strength (Puncture) of Geosynthetics
Authors: Murphy VP , Koerner RM
Published: February 2009

While there exist many types of mechanical tests for use on geosynthetics, most seem to be more suitable for one type of system or another. This paper focuses on a test which may have widespread applicability to assess the strength of all types of geosynthetics. It is the forcing of a 50-mm (2.0-in.) diameter plunger through a horizontally fixed geosynthetic of 150-mm (6.0-in.) diameter. Such dimensions are common to the California bearing ratio (CBR) test apparatus used in assessing soil strength for road subgrades. In actuality, the test is not a puncture test, but is an axisymmetric strength test and should be considered as such. The unsupported geosynthetic is indeed in a state of tension. The stress conditions are well defined, which allow for stress and strain to be calculated and compared to the actual value as obtained in a plane strain (wide width) tension test.

This approach has been followed in this study wherein a wide range of geosynthetics (geotextiles, geomembranes, geonets, and geocomposites) have been tested for CBR (puncture) strength and then calculations performed to determine stress and strain. These calculated values were then compared to those obtained in wide width tests. Results are interesting in that the average values of percent variation between wide width tensile strength and CBR calculated tensile strength for those geosynthetics tested are as follows: (1) geotextiles ±12%, (2) geomembranes ±33%, (3) geonets ±17%, and (4) geocomposites ±10%. It is felt that this type of test (which is basically an index test) is helpful in a number of situations, not the least of which is in assessing strength changes before and after exposure of various geosynthetic materials to chemical or biological incubation.
Determination of the Plastic Limit of a Soil by Means of a Rolling Device
Authors: Bobrowski LJ , Griekspoor DM
Published: February 2009

A rolling device was developed in order to obtain plastic limits in a more expeditious and uniform fashion. The device enables the operator to perform the test on four to five specimens simultaneously. It also dictates that the very strict specification for rolling the soil threads into diameters of 3.2 ± 0.5 mm (0.125 ± 0.020 in.) is met. It removes all subjectivity from the plastic limit determination by governing the diameter of the threads as well as removing any error that may be introduced due to the uniqueness of the human hand. The design and operation of the device are detailed in this paper.
Time-Temperature Superposition in Mechanical Durability Testing of Polyethylene Geomembranes
Authors: Lord AE , Hsuan YG , Koerner RM
Published: February 2009

The mechanical durability of polyethylene geomembranes is considered in this technical note. Polyethylene plastic pipe research has shown that there are universal factors for shifting high-temperature failure (short time) data to low temperatures (long time). Data presented here indicate that these same shift factors may also apply to geomembranes. Crack growth rate studies are proposed as a supplement to the currently used notched constant tensile load tests.
The Multidirectional Direct Simple Shear Apparatus
Authors: DeGroot DJ , Germaine JT , Ladd CC
Published: February 2009

The paper describes a new simple shear testing device, the multidirectional direct simple shear (MDSS) apparatus, for testing soil specimens under conditions that simulate, at the element level, the state of stress acting within the foundation soil of an offshore Arctic gravity structure. The MDSS uses a circular specimen that is consolidated under both a vertical effective stress (σ′vc) and a horizontal shear stress (τ1). The specimen is subsequently sheared undrained by applying a second independent horizontal shear stress (τ2) at an angle ϑ relative to the horizontal consolidation shear stress τ1. Evaluation of the MDSS first compares conventional K0-consolidated undrained direct simple shear (CK0UDSS) test data (τ1 = 0) on normally consolidated Boston blue clay (BBC) with results obtained in the Geonor DSS device. The MDSS gives lower secant Young's modulus values and on average 8% lower strengths, but produces remarkably less scatter in the test results than the Geonor DSS. Kinematic proof tests with an elastic material (rubber) confirm that the setup procedure, application of forces, and strain measurement systems in the MDSS work properly and produce repeatable results.

Results from a MDSS test program on BBC wherein specimens were first normally consolidated with σ′vc and τ1 = 0.2σ′vc and then sheared undrained at ϑ varing in 30° increments from zero (shear in same direction) to 150° show dramatic differences in the response of the soil as a function of θ. The peak undrained strength varies almost twofold from θ = 0 to 120°, while the deformation behavior varies from very brittle at low θ angles to becoming ductile at higher angles. The experimental results indicate that dramatic changes in foundation response at different θ angles will be an important design issue.
Behavior of Fiber-Reinforced Cemented Sand Under Static and Cyclic Loads
Authors: Maher MH , Ho YC
Published: February 2009

Triaxial static compression, cyclic compression, and splitting tension tests were performed to evaluate the effect of randomly distributed fiber reinforcement on the response of cemented sand to load. Test results indicated that fiber reinforcement significantly increases the compressive and splitting tensile strength of cemented sand. An increase in the compressive and tensile strength was found to be more pronounced at higher fiber contents and longer fiber lengths. Peak strength envelopes in compression indicated that both the friction angle and cohesion intercept of cemented sand were increased as a result of fiber inclusion. Inclusion of fibers also contributed to increased brittleness index of cemented sand while increasing its total energy absorption capacity. Fiber reinforcement also affected the response of cemented sand to cyclic load by significantly increasing the number of cycles, and the magnitude of cyclic strain needed to reach failure.
Strain Measurement in HDPE Geomembrane Tensile Tests
Authors: Giroud JP , Monroe M , Charron R
Published: February 2009

According to ASTM D 638, the tensile strain in an HDPE geomembrane dumbbell specimen subjected to a tensile test should be evaluated using an extensometer that records the elongation of a defined length of the central portion of the specimen. However, the current practice in the United States for HDPE geomembrane quality control and conformance testing consists of following the 1991 NSF standard that recommends to conventionally evaluate the tensile strain by dividing the change in grip separation by an arbitrary gauge length. A theoretical analysis and test results presented in this paper show that the strain derived from grip separation using the gauge length specified by the 1991 NSF standard is significantly different from the actual strain, which is obtained using an extensometer as recommended by ASTM D 638. The discrepancy between the conventionally calculated strain and the actual strain may lead to unconservative design of HDPE geomembrane applications. A modification to the NSF standard is proposed to obtain a strain derived from grip separation that is close to the actual strain.
Determination of P-Y Curves Using Inclinometer Data
Authors: Brown DA , Hidden SA , Zhang S
Published: February 2009

Derivation of p-y curves from lateral load tests on deep foundations is a tedious and expensive task, requiring large numbers of strain gages along the length of the pile to develop bending moment versus depth relationships. A method is proposed which allows derivation of p-y curves from simple inclinometer data using a least-squares regression technique. Inclinometer measurements can and have been routinely made on lateral load tests of piles and drilled shafts. The method outlined in this paper provides a means of “calibrating” p-y curves using data from tests where only inclinometer data are available and promises to allow a substantial improvement in the database of load tests from which the empirical p-y curves used in design are based.
Laboratory Filter Paper Suction Measurements
Authors: Houston SL , Houston WN , Wagner A-M
Published: February 2009

Results of filter paper measurements for both matric and total suction values are reported for a sand, silt, and clay. Calibration curves for the matric and total suction are given for the filter paper used in this study, and comparisons with the results of several other researchers are made. For low suction values, the matric suction is more easily measured than the total suction using the filter paper method. This difference is due primarily to the insensitivity of the water content of the noncontact filter paper to changes in suction when the suction is low. A pressure membrane, saturated salt solutions, and tensiometers were used in developing the filter paper calibration curves. Potential pitfalls in making filter paper measurements and limitations of the method are discussed. A procedure for obtaining filter paper suction measurements is given.
Suggested Modifications to ASTM Standard Methods When Testing Arid, Saline Soils
Authors: Al-Amoudi OSB , Abduljauwad SN
Published: February 2009

Arid, saline soils are residual in nature, highly cemented, and formed in hot, arid environments. The presence of soluble and insoluble salts affects the geotechnical properties of these soils. Techniques used to determine the properties of these soils should take into consideration the presence of diagenetic minerals that are considered part of these soils. In this investigation, a typical arid, saline, evaporitic soil, known locally as sabkha, was tested to determine its grain-size characteristics, hydraulic conductivity, compressibility, and collapse potential using standard ASTM methods and nonstandard techniques. The presence of soluble salts necessitates modifications to these standard test methods to properly assess the properties of these soils. Erratum to this paper appears in 17(3).
A Study of an Anisotropically Overconsolidated Silt by the Resonant Column Method
Authors: Macari EJ , Ko H-Y
Published: February 2009

This paper presents the results of a study of the anisotropic characteristics of the shear modulus and damping ratio of a remolded silt that has been uniaxially consolidated. Resonant column tests were conducted on specimens trimmed vertically and horizontally from bulk samples previously subjected to various uniaxial preconsolidation pressures. The tests were performed under various confining pressures, hence resulting in a range of overconsolidation ratios. The degree of anisotropy was defined as the percent difference between the shear modulus of the vertically trimmed specimens and the horizontally trimmed specimens. Empirical relations were found to represent the degree of anisotropy as functions of the overconsolidation ratio and the effective confining pressure.
Investigation of the Strain-Softening Behavior of Granular Soils with a New Multiaxial Cell
Authors: Lo S-CR , Chu J , Lee IK
Published: February 2009

The special considerations leading to the design of a new multiaxial cell used for strain-softening studies are presented. This cell has the special features of being able to accommodate large strain without introducing boundary imperfections, allowing observation of shear band formation, and permitting strain path control. The observed strain-softening behavior of a quartz sand under multiaxial stress condition, i.e., σ'1 ≠ σ'2 ≠ σ'3, are presented. Both stress path tests and strain path tests were conducted. In a stress path test, the specimen was loaded in the major principal direction in a deformation-controlled mode but with the stress response constrained along a prescribed path using computer control. Hence strain-softening response can still be observed in a controlled way. Two types of softening, prefailure and postfailure softening, are identified. Prefailure softening will occur along certain strain paths, and the associated deformation is homogeneous. In postfailure softening under a multiaxial stress condition, only limited homogeneous deformation can be sustained, and eventually there will be shear band formation. However, this shear band is not triggered by boundary imperfections but is an inevitable response of the specimen to shearing in the postfailure domain under a multiaxial stress condition.
Prediction Models of Resilient Modulus for Nongranular Materials
Authors: Pezo R , Hudson WR
Published: February 2009

This paper describes an experimental program and the analyses performed for the purpose of developing prediction models of resilient modulus for nongranular materials. Two models were developed and are presented herein. The first model provides a quick estimation of the resilient modulus based on basic characteristics of the specimens, while the second model includes a family of curves that relate a normalized modulus to the resilient axial strains and the plasticity index of the specimens. The significance of the second model is corroborated particularly now that moduli measurements obtained from field and laboratory tests can be easily related.
A Modified Commercial Triaxial Testing System for Small Strain Measurements: Preliminary Results on Pisa Clay
Authors: Lo Presti DCF , Pallara O , Puci I
Published: February 2009

A computer-controlled hydraulic triaxial cell was modified with the aim of obtaining (1) a better measuring accuracy of soil stiffness at small strains, (2) a reliable automatic procedure for K0 consolidation, and (3) a minimum disturbance during system saturation and specimen consolidation. To obtain the above objectives, many modifications were introduced. The cell structure and loading piston were modified and many transducers were introduced, including the LDTs for local radial and axial strain measurement. Finally, control software was developed to achieve the following testing procedures: (1) dry setting, (2) system saturation by flushing with stress control to avoid any swelling and back pressurization, and (3) K0 consolidation with control of nil radial strain by means of local measurement. The paper will benefit those interested in upgrading an existing hydraulic triaxial system in-house in an economical manner.
A Direct Simple Shear Device for Measuring Small-Strain Behavior
Authors: Doroudian M , Vucetic M
Published: February 2009

A simple shear device named the double specimen direct simple shear (DSDSS) device was designed to investigate static and cyclic properties of soils at small strains, such as cyclic stress-strain loops, maximum shear modulus, Gmax, secant shear modulus, Gs, and the equivalent viscous damping ratio, λ. Cyclic shear strains between 5 × 10−4 and 2 × 10−2% were successfully applied and measured. Such measurements of very small strains were achieved by completely eliminating the friction of the load-transfer mechanism and by reducing the effects of the mechanical compliance of the device to practically zero. This was facilitated by using a special configuration of two parallel specimens. The performance of the DSDSS device was examined first by testing rubber dummy specimens of different stiffnesses and then by conducting a series of tests on kaolinite clay consolidated under different vertical consolidation stresses and over-consolidation ratios. The results produced by the new device show very consistent trends and are in good agreement with equivalent data obtained by others using other types of tests and equipment.
Permeability and Compressibility Behavior of Bentonite-Sand/Soil Mixes
Authors: Pandian NS , Nagaraj TS , Raju PSRN
Published: February 2009

As a seepage barrier, slurry trench material should have a relatively low coefficient of permeability, in the range of 10−7 cm/s, and at the same time should be compatible with surrounding material with regard to compressibility. Although bentonite-sand/soil mixes are used widely, there is no specific engineering approach to proportion these mixes that satisfies the above practical requirements. In this paper, a generalized approach is presented for predicting the permeability and compressibility characteristics of mixes with minimum input parameters. This approach will be helpful in proportioning mixes and predicting corresponding changes in engineering behavior. It is possible to proportion a mix to arrive at the required compressibility without affecting the permeability. This is explained using an illustrative example.
A New Filter Material for Measuring Soil Suction
Authors: Sibley JW , Williams DJ
Published: February 2009

The filter paper method for determining soil suction has been in use for many years and owes its attraction to its simplicity. A major drawback of the method is that the suction range over which it can be applied is limited by the moisture sensitivity of the filter paper or absorbent used. By convention, filter paper has been adopted for use in the method, but other absorbents may well be more suitable, increasing the sensitivity of the method and extending the suction range over which the method may usefully be applied. In this paper the desirable attributes of absorbents for use in determining soil suctions are outlined, and the suitability of a nonconventional absorbent material is assessed. It was found that this material had enhanced sensitivity over the middle suction range.
Laboratory and Field Calibration of a Neutron Depth Moisture Gauge for Use in High Water Content Soils
Authors: Silvestri V , Sarkis G , Bekkouche N , Soulie M , Tabib C
Published: February 2009

In recent years radioisotopes have been increasingly used for determining site values of the density and the water content of soils. Since field measurements obtained by neutron moisture gauges are relative, these instruments must be calibrated. Calibration is usually carried out in the laboratory by plotting neutron counting rates versus known water content values of several soil media, homogeneous as well as heterogeneous.

The accuracy of the factory calibration curve of a widely used, commercial neutron depth moisture gauge was evaluated both in the field and in the laboratory by comparing probe readings to measured volumetric water contents of several soil mixtures. The analyses of the laboratory results indicate that the factory linear calibration curve is satisfactory for volumetric water contents not exceeding 40%. However, for volumetric water contents in the range from 40 to 100%, the relationship between probe readings and volumetric water contents is nonlinear. This nonlinear curve was found to be quite different from that obtained in the field calibration campaign carried out in a deposit of sensitive Champlain clay having volumetric water contents which compare well with those of the laboratory-prepared clay mixtures.
Determination of Clay Size Fraction of Marine Clays
Authors: Sridharan A , Jose BT , Abraham BM
Published: February 2009

This technical note describes a study on the effect of different dispersing agents and the quantity of same on the grain-size distribution and in particular the percentage of clay size. The results confirm that the existing practice of using 100 mL of standard dispersing agent, viz. sodium hexametaphosphate and sodium carbonate solution, is suitable for marine clays also. The clay size fraction in a marine soil exists in the form of flocs, and hence a dispersing agent is imperative in determining the percentage of clay size fraction. This paper shows that the clay size fraction can vary significantly (4 to 45%) for the marine clays depending upon the dispersing agent used. It also brings out the importance of the need for using an initially moist sample for grain-size analysis in the case of marine clays. Initial air/oven drying before testing induces irreversible aggregation.
Design and Performance of the Imperial College Instrumented Pile
Authors: Bond AJ , Jardine RJ , Dalton JCP
Published: February 2009

This paper describes the design, calibration, and field performance of a number of new instruments that have been used for research into the behavior of displacement piles in clays and sand. The instruments include axial load cells, surface stress transducers, and pore pressure probes. The special features of the surface stress transducers and pore pressure probes are described in detail, and problems associated with measuring pore pressures in strongly dilating soils are discussed. Data recorded at a stiff clay site are used to demonstrate the reliability of measurements obtained with the new instruments.