bluuebunny/crossref_metadata_2025 huggingface dataset:
A Role for the CHC22 Clathrin Heavy-Chain Isoform in Human Glucose Metabolism
Authors: Vassilopoulos Stéphane , Esk Christopher , Hoshino Sachiko , Funke Birgit H. , Chen Chih-Ying , Plocik Alex M. , Wright Woodring E. , Kucherlapati Raju , Brodsky Frances M.
Published: May 2009

GLUT4, Clathrin, and Glucose

In human muscle, the GLUT4 glucose transport pathway responds to insulin and is responsible for 70 to 90% of human glucose clearance. In the basal metabolic state, GLUT4 is sequestered away from the cell surface and is released from an intracellular membrane compartment in response to insulin. This GLUT4 membrane pathway is defective in type II diabetes.

Vassilopoulos
et al.

(p.
1192
; see the Perspective by
Orme and Bogan
) now describe a function for CHC22 clathrin, a second isoform of clathrin that is present in humans and not in mice. CHC22 participates in the biogenesis of the intracellular compartment that sequesters the GLUT4 glucose transporter for insulin-stimulated release. Because CHC22 is restricted to humans, mice differ in their pathways that control glucose metabolism, which may restrict the utility of the mouse as a model system in assessing glucose metabolism and diabetes.
Celebrating the 400th Anniversary of Telescope Astronomy
Authors: Bignami Giovanni F.
Published: May 2009

Since Galileo looked skyward 400 years ago, telescopes have evolved to provide a broader and deeper understanding of the universe.
Synthetic Gene Networks That Count
Authors: Friedland Ari E. , Lu Timothy K. , Wang Xiao , Shi David , Church George , Collins James J.
Published: May 2009

One, Two, Three

Synthetic biologists take much of their inspiration from computing and electrical engineering, attempting to gain programmability in cells using analogous genetic circuits.

Friedland
et al.

(p.
1199
; see the Perspective by
Smolke
) have constructed complementary
Escherichia coli
synthetic gene networks that keep track of prior molecular events to function as counters. These modular devices count up to three induction events over a range of frequencies and could be extended to higher numbers. Similar devices may find application in multi-event processes of cell biology, bioengineering, and, potentially, therapeutics.
Getting in Touch with Your Friends
Authors: Marx Christopher J.
Published: May 2009

Evolution of complex physical interactions between microbes promotes growth and enables behaviors that neither party can perform alone.
Slabs Do Not Go Gently
Authors: Nolet Guust
Published: May 2009

High-resolution seismic tomography reveals an active vertical tear in a descending ocean plate off the coast of Japan.
Sorting Out Diabetes
Authors: Orme Charisse M. , Bogan Jonathan S.
Published: May 2009

Altered trafficking of storage vesicles that harbor a glucose transport protein in muscle and fat tissue may contribute to diabetes.
Celebrity Fossil Primate: Missing Link or Weak Link?
Authors: Gibbons Ann
Published: May 2009

A 47-million-year-old fossil primate has been touted as the "missing link" between humans and all other mammals. But many of the leading scientists who study primate evolution don't think Ida lives up to her billing as a human ancestor.
Obama Turns to NASA Veterans to Lead Space Agency
Authors: Lawler Andrew
Published: May 2009

On 23 May, President Barack Obama nominated former astronaut Charles Bolden Jr. and Washington lobbyist Lori Garver to take the positions of NASA administrator and deputy administrator, respectively.
As Research Funding Declines, Chávez, Scientists Trade Charges
Authors: Casassus Barbara
Published: May 2009

Tensions are growing between the Venezuelan scientific community and President Hugo Chávez. Critics say that research is being mismanaged, and that the government has fired, demoted, or blacklisted dissidents.
New Details on Virus's Promiscuous Past
Authors: Cohen Jon
Published: May 2009

An international team of scientists working at breakneck speed has provided the most detailed description yet of the origins of the novel H1N1 swine flu virus now causing a global outbreak,
published online
by
Science
on 22 May.
The Money to Meet the President's Priorities
Authors: Mervis Jeffrey
Published: May 2009

The National Science Foundation has turned recent actions by Congress and the priorities of a new president into an array of programs to strengthen the scientific work force, tackle pressing societal problems, and foster collaborations across disciplines.
Digging for Fresh Ideas in the Sandpit
Authors: Mervis Jeffrey
Published: May 2009

Does the idea of writing a grant proposal that's been all but approved before it's even sent in sound appealing? Then play in the sandpit.
Mystery of the Missing Humpbacks Solved by Soviet Data
Authors: Morell Virginia
Published: May 2009

A paper in
Marine Fisheries Review
concludes that the high number of unreported catches by Soviet whalers of humpbacks in the Southern Ocean decimated this population so severely that unlike humpback populations elsewhere, it has not yet recovered.
Protecting the Last Great Tuna Stocks
Authors: Pala Christopher
Published: May 2009

Representatives of Western Pacific island nations last week put the finishing touches on a series of bold new measures aimed at saving the world's last great tuna stocks.
Gut Reactions
Authors: Pennisi Elizabeth
Published: May 2009

A young microbial ecologist is helping to transform medical microbiology into a modern interdisciplinary science.
Immunological Profiles of
Bos taurus
and
Bos indicus
Cattle Infested with the Cattle Tick,
Rhipicephalus
(
Boophilus
)
microplus
Authors: Piper Emily K. , Jonsson Nicholas N. , Gondro Cedric , Lew-Tabor Ala E. , Moolhuijzen Paula , Vance Megan E. , Jackson Louise A.
Published: May 2009

The cattle tick,
Rhipicephalus
(
Boophilus
)
microplus
, is a major threat to the improvement of cattle production in tropical and subtropical countries worldwide.
Bos indicus
cattle are naturally more resistant to infestation with the cattle tick than are
Bos taurus
breeds, although considerable variation in resistance occurs within and between breeds. It is not known which genes contribute to the resistant phenotype, nor have immune parameters involved in resistance to
R. microplus
been fully described for the bovine host. This study was undertaken to determine whether selected cellular and antibody parameters of the peripheral circulation differed between tick-resistant
Bos indicus
and tick-susceptible
Bos taurus
cattle following a period of tick infestations. This study demonstrated significant differences between the two breeds with respect to the percentage of cellular subsets comprising the peripheral blood mononuclear cell population, cytokine expression by peripheral blood leukocytes, and levels of tick-specific immunoglobulin G1 (IgG1) antibodies measured in the peripheral circulation. In addition to these parameters, the Affymetrix bovine genome microarray was used to analyze gene expression by peripheral blood leukocytes of these animals. The results demonstrate that the
Bos indicus
cattle developed a stabilized T-cell-mediated response to tick infestation evidenced by their cellular profile and leukocyte cytokine spectrum. The
Bos taurus
cattle demonstrated cellular and gene expression profiles consistent with a sustained innate, inflammatory response to infestation, although high tick-specific IgG1 titers suggest that these animals have also developed a T-cell response to infestation.
Validation of the SPF
10
LiPA Human Papillomavirus Typing Assay Using Formalin-Fixed Paraffin-Embedded Cervical Biopsy Samples
Authors: Dal Bello Barbara , Spinillo Arsenio , Alberizzi Paola , Cesari Stefania , Gardella Barbara , Silini Enrico Maria
Published: May 2009

Lower levels of performance of human papillomavirus (HPV) typing assays in studies using formalin-fixed paraffin-embedded (FFPE) tissue compared to those using exfoliated cervical cells have been reported. The interpretation of current studies is limited by bias in inclusion criteria, sample matching, and methods of cell collection. We aimed to validate FFPE tissue for typing by the use of the SPF
10
LiPA assay, comparing cervical scrapings to punch and cone biopsy specimens. We examined 165 paired cervical scraping and FFPE punch biopsy samples, and 66 paired FFPE punch and cone biopsy samples. HPV typing was performed using the SPF
10
LiPA assay. Kappa statistics were used to measure interrater agreement. The overall agreement with respect to HPV status was 100%. For 74.5% of subjects (kappa = 0.6147), the same numbers of HPV types were detected in scraping and biopsy specimens. The overall positive typing agreement was 95.4% (range, 93.4 to 97.3) for 441 out of 484 individual HPV type analyses. Agreement was good for HPV-39, -42, -43, and -70 (kappa = 0.6506 to 0.7166), excellent for HPV-6, -16, -18, -31, -33, -35, -40, -51, -52, -56, -58, and -66 (kappa = 0.8499 to 0.9665), and absolute for HPV-11, -44, -45, -53, and -68. In 43.9% of cases (kappa = 0.247), the same numbers of HPV types were found in punch and cone biopsy specimens. Overall positive agreement for typing was 86.8% (range, 82.5 to 91.1) for 204 out of 266 individual HPV type analyses. More infections by HPV-18, -33, -51, and -52 were detected in cone specimens. HPV typing by SPF
10
LiPA performed equally well for cervical scraping specimens and standard pathological material. Some viral types are preferentially detected in cone specimens, likely reflecting better sampling of diseased epithelium and endocervix tissue.
Detection and Genomic Characterization of Aichi Viruses in Stool Samples from Children in Monastir, Tunisia
Authors: Sdiri-Loulizi Khira , Hassine Mouna , Gharbi-Khelifi Hakima , Sakly Nabil , Chouchane Slaheddine , Guediche Mohamed Neji , Pothier Pierre , Aouni Mahjoub , Ambert-Balay Katia
Published: May 2009

Aichi virus has been associated with acute gastroenteritis in adults and children. Stool samples were collected from 788 Tunisian children suffering from diarrhea. Aichi virus was found in 4.1% of the cases. The high proportion of monoinfections and the high frequency of hospitalizations support the role of Aichi virus in pediatric gastroenteritis.
Proline and Tyrosine Residues in Scaffold Proteins of Herpes Simplex Virus 1 Critical to the Interaction with Portal Protein and Its Incorporation into Capsids
Authors: Yang Kui , Baines Joel D.
Published: May 2009

Previous results showed that amino acids 449 to 457 of pU
L
26, a component of the scaffold of herpes simplex virus 1 capsids, were critical for interaction with the portal protein encoded by U
L
6 and for incorporation of the portal into capsids. To identify residues in this scaffold domain critical for the interaction with pU
L
6, the two proteins were coexpressed in the absence of other viral proteins and subjected to immunoprecipitation with scaffold-specific antibody. Coimmunoprecipitation of pU
L
6 was precluded by pU
L
26 mutations Y451A, P452A, and E454A but not by P449A, R456A, or Y450A. In infected cells, Y451A and P452A diminished solubilization of pU
L
6, reduced incorporation of the portal into the capsid, and precluded viral replication and DNA packaging. In contrast, E454A did not affect these parameters despite the fact that E454 is invariant in a number of different alphaherpesvirus scaffold proteins. These data suggest that the interaction between the scaffold E454A mutant and portal protein is rescued by other viral functions. Finally, we show that amino acids 448 to 459 of pU
L
26 are sufficient to interact with pU
L
6 in a glutathione
S
-transferase pulldown assay in the absence of other viral proteins and that this interaction is inhibited with excess peptide containing pU
L
26 amino acids 443 to 462. Together, these observations suggest that a direct interaction between this scaffold domain and portal protein mediates incorporation of the portal into the capsid.
Cross-Subtype Neutralization Sensitivity despite Monoclonal Antibody Resistance among Early Subtype A, C, and D Envelope Variants of Human Immunodeficiency Virus Type 1
Authors: Blish Catherine A. , Jalalian-Lechak Zahra , Rainwater Stephanie , Nguyen Minh-An , Dogan Ozge C. , Overbaugh Julie
Published: May 2009

The human immunodeficiency virus type 1 (HIV-1) variants that are transmitted to newly infected individuals are the primary targets of interventions, such as vaccines and microbicides, aimed at preventing new infections. Newly acquired subtype A, B, and C variants have been the focus of neutralization studies, although many of these viruses, particularly of subtypes A and B, represent viruses circulating more than a decade ago. In order to better represent the global diversity of transmitted HIV-1 variants, an additional 31 sexually transmitted Kenyan HIV-1
env
genes, representing several recent infections with subtype A, as well as subtypes A/D, C, and D, were cloned, and their neutralization profiles were characterized. Most
env
variants were resistant to neutralization by the monoclonal antibodies (MAbs) b12, 4E10, 2F5, and 2G12, suggesting that targeting the epitopes of these MAbs may not be effective against variants that are spreading in areas of endemicity. However, significant cross-subtype neutralization by plasma was observed, indicating that there may be other epitopes, not yet defined by the limited available MAbs, which could be recognized more broadly.
Novel Ring Structure in the gp41 Trimer of Human Immunodeficiency Virus Type 1 That Modulates Sensitivity and Resistance to Broadly Neutralizing Antibodies
Authors: O'Rourke Sara M. , Schweighardt Becky , Scott William G. , Wrin Terri , Fonseca Dora P. A. J. , Sinangil Faruk , Berman Phillip W.
Published: May 2009

The identification of the determinants of sensitivity and resistance to broadly neutralizing antibodies is a high priority for human immunodeficiency virus (HIV) research. An analysis of the swarm of closely related envelope protein variants in an HIV-infected individual revealed a mutation that markedly affected sensitivity to neutralization by antibodies and antiviral entry inhibitors targeting both gp41 and gp120. This mutation mapped to the C34 helix of gp41 and disrupted an unexplored structural feature consisting of a ring of hydrogen bonds in the gp41 trimer. This mutation appeared to affect the assembly of the six-helix bundle required for virus fusion and to alter the conformational equilibria so as to favor the prehairpin intermediate conformation required for the binding of the membrane proximal external region-specific neutralizing antibodies 2F5 and 4E10 and the antiviral drug enfuvirtide (Fuzeon). The “swarm analysis” method we describe furthers our understanding of the relationships among the structure, function, and antigenicity of the HIV envelope protein and represents a new approach to the identification of vaccine antigens.
Consistency in size and asymmetry of the psoas major muscle among elite footballers
Authors: Stewart S , Stanton W , Wilson S , Hides J
Published: May 2009

Objective

To determine, using magnetic resonance imaging (MRI), the cross-sectional area (CSA) of the psoas major (PM) muscle across multiple vertebral levels, to examine any asymmetry of the PM muscle and investigate the consistency across vertebral levels, and to determine whether a relationship exists between low back pain (LBP) and the size or asymmetry of the PM muscle among elite Australian Rules football (AFL) players.

Design

Observational cross-sectional study.

Setting

Assessments and MRI examinations were carried out in a hospital setting.

Participants

Thirty-one male elite AFL players aged between 20 and 32 years participated in the study.

Risk Factors

The independent factors in the study were “asymmetry” (coded as ipsilateral or contralateral to kicking leg) and “group” (current LBP versus no current LBP).

Main Outcome Measurements

The dependent variable in the study was the CSA of the PM muscle.

Results

The PM muscle was larger on the side of the dominant kicking leg at all four vertebral levels measured (F = 7.28, p = 0.012). Participants who reported current LBP had larger PM muscles than the remainder of the players (F = 4.63, p = 0.041).

Conclusion

Additional investigation into the underlying mechanisms of the observed differences in PM muscle size could help to develop treatment and rehabilitation programmes aimed at reducing the incidence of LBP among AFL players. Furthermore, asymmetry of the PM muscle was observed at multiple vertebral levels and therefore future studies may only need to take single-level measurements to assess for asymmetry.
Evaluation of the incidental and planned activity questionnaire for older people
Authors: Delbaere K , Hauer K , Lord S R
Published: May 2009

Objective

There is a need for a measure of physical activity that assesses low, basic and high-intensity activities suitable for use in ageing research including falls prevention trials. This study performed a formal validation of the incidental and planned activity questionnaire (IPAQ) by investigating its overall structure and measurement properties.

Design

Cross-sectional survey.

Setting

Community sample.

Participants

500 older people (mean age 77.4 years, SD 6.08).

Main Outcome Measures

The IPAQ was administered as part of a longer assessment in two different postal self-completion formats; one for estimating physical activity during the past week (IPAQ-W) and one for estimating average weekly physical activity over the past 3 months (IPAQ-WA). Test–retest reliability was assessed by the re-administration of the instruments one week later in a subsample of 80 respondents.

Results

Both IPAQ versions had good measurement properties, but overall the IPAQ-WA performed better than the IPAQ-W. Rasch analyses indicated the IPAQ-WA had an excellent overall fit. Analysis of the internal structure supported the unidimensionality of the scale with an acceptable internal consistency. The content representation of the items revealed three categories (low, moderate and high levels of physical activity), with a good contribution of items by threshold. The IPAQ-WA had excellent test–retest reliability, intraclass correlation coefficient 0.87) and was able to discriminate differences in physical activity levels between groups differentiated by sex, age and fall risk factors.

Conclusions

The IPAQ has excellent psychometric properties and assesses the level of physical activity relating to both basic and more demanding activities. Further research is required to confirm sensitivity to change.
Evaluation of a commercially available pedometer used to promote physical activity as part of a national programme
Authors: Clemes S A , O'Connell S , Rogan L M , Griffiths P L
Published: May 2009

Objective

To assess the accuracy of a pedometer (manufactured by Silva) currently being used as part of a national programme to promote physical activity in the UK.

Methods

Laboratory study: 68 participants (aged 19.2 years (SD 2.7), body mass index (BMI) 22.5 kg/m2(SD 3.3)) wore two Silva pedometers (over the right and left hips) while walking on a motorised treadmill at 2, 2.5, 3, 3.5 and 4 mph. Pedometer step counts were compared with actual steps counted. Free-living study: 134 participants (aged 36.4 years (SD 18.1), BMI 26.3 kg/m2(SD 5.1)) wore one Silva pedometer, one New-Lifestyles NL-1000 pedometer and an ActiGraph GT1M accelerometer (the criterion) during waking hours for one day. Step counts registered by the Silva and NL-1000 pedometers were compared with ActiGraph step counts. Percentage error of the pedometers were compared across normal-weight (n = 58), overweight (n = 45) and obese (n = 31) participants.

Results

Laboratory study: Across the speeds tested percentage error in steps ranged from 6.7 (4 mph) to 46.9% (2 mph). Free-living study: Overall percentage errors of the Silva and NL-1000 pedometers relative to the criterion were 36.3% and 9%, respectively. Significant differences in percentage error of the Silva pedometer were observed across BMI groups (normal-weight 21%, overweight 40.2%, obese 59.2%, p<0.001).

Conclusion

The findings suggest the Silva pedometer is unacceptably inaccurate for activity promotion purposes, particularly in overweight and obese adults. Pedometers are an excellent tool for activity promotion; however, the use of inexpensive, untested pedometers is not recommended as they will lead to user frustration, low intervention compliance and adverse reaction to the instrument, potentially impacting future public health campaigns.
A Simple Ko Triaxial Cell
Authors: Campanella R. G. , Vaid Y. P.
Published: May 2009

The need to reproduce the same stress path in the laboratory as in the field is emphasized, especially for initial consolidation, which in most cases is under Ko conditions. A simplified Ko triaxial cell is described, which permits initial Ko consolidation without any adjustments. A loading system is described, which permits a variety of stress paths during shear (either passive or active, compression or extension, by strain control or stress control loading, under drained or undrained conditions).The ease of sample preparation and test procedure is pointed out and characteristics of the new apparatus are described. Typical data are presented during both consolidation and loading under all possible stress paths, which demonstrates the consistency of results, the flexibility of the new apparatus, and the variation in soil behavior as a function of stress path.
Strength Anisotropy and Time Effects of Two Sensitive Clays
Authors: Lo K. Y. , Morin J. P.
Published: May 2009

A comprehensive experimental investigation was performed on block samples of two sensitive clays taken from the sites of recent slides in Quebec. Both isotropically consolidated drained and undrained triaxial tests were carried out on specimens trimmed at various angles from the vertical direction. Direct and indirect drained tension tests were also performed so as to cover the entire stress range from tensile to compressive stresses beyond the preconsolidation pressure.Results of this study showed that the effective stress strength envelopes are pronouncedly nonlinear and strongly anisotropic in the working stress range usually encountered. The ratio of minimum strength to strength of vertical samples varies from 0.54 to 0.70. The drained tensile strength is also anisotropic, the value obtained for fracture across stratification is about three times that along stratification. The time to failure has an important effect on the peak strength.The post-peak behavior was studied and it is shown that the strength at large strains may be deduced from results of CIU and CID tests.The modulus of deformation varies with consolidation pressure in a manner similar to that of the peak strength envelope. It is essentially isotropic, but decreases with strain rate.Finally, application of these results to slope stability problems is discussed.
Field Loading Tests on Muskeg
Authors: Hollingshead Garry W. , Raymond Gerald P.
Published: May 2009

Results of tests performed using a 1.8-m (6-ft) diameter flexible based tank capable of being filled with 3.6 m (12 ft) of water are presented. Two series of tests were performed on a muskeg with an undrained shear strength of 5–7.5 kN/m2 (100–150 lb/sq.ft). The first consisted of filling the tank alone and the second with the tank positioned at the center of a 4.5-m (15-ft) diameter 0.6 m (2 ft) high flexible based reservoir. The results thus simulate the comparison of the effect of berms on the stability of embankments. Consideration is given to the short term effect of berms where they are constructed rapidly at the same time as the central fill and the long term effect where they and the central fill are constructed slowly.The resulting vertical movements were measured using a torpedo settlement gauge. The horizontal movements were measured using an inclinometer as well as a horizontal movement device. The pore pressures were measured using fine stoned piezometers.In addition suitable laboratory tests were conducted to compare predicted and measured results.
Engineering Geology Aspects Relating to Preliminary Damsite Investigations on the Nelson River, Manitoba
Authors: Piteau Douglas R.
Published: May 2009

Engineering geology aspects of the preliminary investigation of nine alternative damsites along the lower reach of the Nelson River between Split Lake and Hudson Bay, Manitoba, Canada are described.Glacial drift, comprising mainly ablation and basal till, almost completely blankets the area, and active slope failures are common. The western part of the area is underlain by Precambrian rocks, which in the eastern part of the area are overlain by Paleozoic dolomitic limestone. Discontinuous permafrost conditions particularly presented some interesting terrain and investigation problems.The engineering geology studies included airphoto interpretation, both reconnaissance and detail geologic mapping, trenching, drilling, seismic-refraction surveys, river soundings, and ground surveys.
In-situ Determination of Undrained Stress-strain Behavior of Sensitive Clays with the Pressuremeter
Authors: Ladanyi B.
Published: May 2009

A theory originally proposed by Gibson and Anderson (1961) has been extended to enable a direct determination of the whole undrained stress-strain curve of the clay from the pressure-expansion curve obtained in a conventional pressuremeter test.When applied to some pressuremeter tests carried out in Leda clay in the Ottawa area, the method enabled us to determine the undrained stress-strain behavior of the clay up to axial strains of about 20%. It is thought that, when properly performed, the test is able to furnish the data on the undrained stress-strain and strength properties of sensitive clays comparable to the laboratory test results obtained on block samples. Its particular feature is that it also furnishes a true picture of the post-peak strength decrease in terms of shear strain which is usually difficult to obtain by any other type of test.
Pile capacity for eccentric inclined load in clay
Authors: Meyerhof G. G. , Yalcin A.S.
Published: May 2009

In connection with the design of offshore structures and bridge foundations, the ultimate bearing capacity of rigid piles and pile groups in clay has been determined under various combinations of eccentricity and inclination of the load varying from the vertical to horizontal directions. The results of load tests on single rigid model piles and freestanding groups are compared with theoretical estimates. The influence of eccentricity and inclination of the load on the ultimate bearing capacity can be represented by simple interaction relationships between the ultimate loads and moments and between the axial and normal components of the ultimate load. The effect of a pile cap resting on the soil in piled foundations and the influence of pile flexibility on the ultimate load are examined briefly. Key words: bearing capacity, clay, eccentric load, inclined load, pile groups, pile–soil interaction, rigid piles, ultimate load, ultimate moment.
Reinforced earth retaining wall under vertical and horizontal strip loading
Authors: Laba J. T. , Kennedy J. B. , Seymour P. H.
Published: May 2009

A study was carried out on the structural response of a reinforced earth retaining wall model subjected to the action of a surcharge strip load aligned parallel to the wall head. Effects of both vertical and horizontal load components were investigated. Horizontal loads were applied in two directions, namely, towards the wall face and away from the wall face. The stress distribution pattern in the reinforcing elements and the change in stress distribution occurring in the reinforced earth medium were also studied. Results were generated for various loading conditions, including variations in the load distance from the wall face. Contour diagrams showing the ratio of reinforcing element stress to applied horizontal load intensity, as well as contour diagrams showing the ratio of horizontal soil stress to applied horizontal load intensity, were constructed. Experimental results were compared with the theoretical stress distribution that exists in a semi-infinite elastic medium, and also with design procedure currently in use for reinforced earth retaining walls under horizontal surcharge strip loading. Significant differences were found between the results based on the design method now in use and those obtained from the model study. Key words: reinforced earth, vertical and horizontal strip load, reinforcing elements, stress distribution, stress-sensitive regions, contours, deflections.
A steady state model for flow in saturated–unsaturated soils
Authors: Papagianakis A. T. , Fredlund D. G.
Published: May 2009

A model is proposed describing continuous flow between saturated and unsaturated soil. The flow is assumed to be two dimensional and under steady state conditions. In the unsaturated zone, the coefficient of permeability is treated as a function of pore-water pressure head. The nonlinear differential equation governing the flow is solved using an iterative finite element scheme. The flow equation for an element is derived using the Galerkin weighed residuals method. Several example problems are solved and compared with flow net solutions. The proposed flow model is superior to traditional models, which consider flow only in the saturated zone. The results show that the zero pressure isobar is not an upper flow boundary. The finite element solution is shown to be relatively insensitive to the function used to express the relationship between the coefficient of permeability and the pore-water pressure head. Key words: saturated–unsaturated, pore-water pressure, head, phreatic line.
Laterally loaded piles in permafrost
Authors: Nixon J. F. (Derick)
Published: May 2009

A theory for the design of laterally loaded piles in permafrost is presented. The approach is valid for icy soils or ice, where secondary creep displacements will be responsible for the majority of the soil strain under sustained load. Initially, the paper studies in some detail the response of a short, rigid pile embedded in a nonlinear viscous medium. The concept of a flexible elastic pile in a viscous continuum is then introduced, and a relatively straightforward numerical procedure must be introduced to obtain a solution. Once the limiting or design ground surface displacement rate is established by the designer, the paper shows how a typical chart relating lateral pile load to average ground temperature can be prepared.The available (but limited) data base is reviewed for field pile load tests carried out in the early 1970's in Inuvik, N.W.T. and some laboratory model pile tests carried out in connection with this study. Using available long-term secondary creep data for ice and icy silts, predictions for the lateral creep response of piles can be carried out. Agreement between prediction and observation is certainly encouraging and points the way to further research and field testing in this area. Finally, the paper briefly discusses the resistance of rigid fixed-headed piles to lateral loads, and the resistance of a pile in permafrost to the application of a pure moment. Key words: lateral piles, permafrost, creep, model, field tests.
Impact resistance of three soils under varying moisture and subzero temperature conditions
Authors: Zebarth B. J. , Lee D. , Kay B. D.
Published: May 2009

Impact resistance, the deceleration-time response of a moving body upon impact with a surface, can be used to measure the hardness of a soil surface. A simple method for measuring impact resistance is presented. Impact resistance of three soils (Preston sand, Haldimand clay, and Guelph loam) was measured over a range of moisture and subzero temperature conditions. Impact resistance of frozen soil was found to increase with increasing moisture content, decreasing temperature, and increasing particle diameter. Temperature effects on impact resistance were minimal below −4 °C. Under field conditions, increased impact resistance due to increased particle diameter may be compensated for by reduced moisture content. Key words: density, dynamic loading, grain size, soil strength, sports fields.
Geotechnical parameters and behaviour of uranium tailings
Authors: Matyas Elmer L. , Welch Donald E. , Reades Denys W.
Published: May 2009

The results of laboratory and in situ testing and test blasting, the observations made on a test embankment, and a description of actual construction practice associated with engineering studies for the management of uranium mill tailings at Elliot Lake, Ontario are presented. Relative density values inferred from standard penetration tests and cone penetrometer tests are shown to be inconsistent with relative density values determined from maximum and minimum void ratios. Some of the data contradicts existing correlations.The compressibility of in situ saturated tailings is presented in graphical form in terms of void ratio, vertical effective stress, and mean grain size. Hydraulic conductivity is shown to range over many orders of magnitude, depending on the void ratio. The observations on an instrumented test embankment are used to explain the appropriate selection of geotechnical parameters that gave good agreement between back-calculated and observed settlements. One-dimensional consolidation theory was found to be valid for the embankment case. It is necessary to account for changes in soil properties that occur during the consolidation process in order to obtain a good fit between back-calculated and observed settlements. The successful use of tailings sand for embankment construction is described. On the basis of normalized standard penetration resistance values, it is concluded that localized zones of saturated tailings may be prone to liquefaction under predicted earthquake loadings. Key words: uranium tailings, geotechnical parameters, relative density, test embankment, liquefaction.
Creep and strength testing of frozen saline fine-grained soils
Authors: Nixon J. F. , Lem G.
Published: May 2009

Little creep data is available for frozen, fine-grained saline soils. Salinity accelerates the creep rate of a frozen soil under load and reduces its shear strength owing to the higher unfrozen water contents in the pore phase. Creep data for saline fine-grained soils are required by engineers and scientists working in areas of coastal or offshore permafrost. The data are also used in projects involving artificial freezing of saline soils.This paper describes the results of 34 creep tests and 11 time-dependent strength tests carried out on saline soils. The tests were carried out for two different research programs; consequently, two different fine-grained soil types were used. Most of the tests were carried out in a constant stress and constant temperature creep test environment. Some were completed in a triaxial (constant strain rate) test format, in order to extend the data base to an area of higher strain rates. The range of temperatures was −2.3 to −25 °C, the range of stresses in the creep tests was 30–400 kPa, and the salinity was varied from 0–35 parts per thousand (ppt). Particular attention was paid to the lower stresses (30–200 kPa) and intermediate to high salinities (18–35 ppt). A high percentage of the creep tests was completed in the temperature range −5 to −10 °C, as this appears to be a typical ground temperature in coastal permafrost areas in Arctic Canada.Results indicate that the presence of pore fluid with a salinity approaching that of seawater causes a 10- to 100-fold increase in uniaxial creep rate, which can result in significant decreases in shear strength and foundation bearing capacity in saline permafrost areas.Soil resistivity tests were also carried out on frozen samples of different salinities. A strong correlation between resistivity and pore water salinity emerged. This has application in the interpretation of results from electrical resistivity surveys in permafrost. Key words: permafrost, saline, creep, strength, resistivity, fine-grained, offshore permafrost.
Piezometer–friction cone investigation at a tailings dam
Authors: Campanella R. G. , Robertson P. K. , Gillespie D. , Klohn E. J.
Published: May 2009

Static piezometer–friction cone tests were carried out at the tailings dam at Brenda Mines, Peachland, British Columbia to evaluate soil characteristics and seepage conditions in the dam. Several types of electric quasistatic cones were pushed to depths of 40–70 m at various locations in the dam and on the beach. The cones used included both the Fugro electric friction cone and piezometer cone, and a University of British Columbia designed piezometer–friction cone.Site conditions are described and typical cone logs of bearing, friction, friction ratio, and pore water pressure vs. depth are presented, interpreted, and discussed. The cone data is used to assess strength and relative density, and to assess gradational variations of the tailings and slimes on the beach, including the identification of ice inclusions.Measurements of equilibrium pore water pressures with depth at three locations on the beach allowed a clear picture to be developed of the pore pressure gradients within the dam. Other problems and experiences concerning quasistatic cone logging for a tailings dam are also discussed. Key words: in situ testing, static penetration testing, piezometer cone, tailings dam, tailings beach, seepage, strength, relative density, ice, pore pressures.
Analysis of a geotextile-reinforced embankment constructed on peat
Authors: Rowe R. K. , Maclean M. D. , Soderman K. L.
Published: May 2009

This paper describes a finite element analysis of two instrumented sections of a geotextile-reinforced embankment constructed on peat. The results from the analysis provide very encouraging agreement with the field observations for both instrumented sections at the endof the two major stages of construction. It is shown that the drained strength parameters c′ = 1.8 kPa, [Formula: see text] determined from simple shear apparatus provided the best agreement between predicted and observed behaviour. Analyses were also performed using both the field vane strength and the drained shear parameters (c′ = 0, [Formula: see text]) determined from triaxial tests, and the implications of these analyses are discussed. The geotextile–fill interface strength properties are also presented and it is suggested that, in this embankment, interface slip was not a factor affecting embankment performance.The analysis indicates that the major effect of the high modulus geotextile (Geolon 1250) used in the deepest section of the deposit was to reduce lateral movements, although it may have slightly reduced vertical movements as well. It is concluded that even a very high modulus geotextile will not prevent large consolidation settlements of embankments on peat.

Key words: embankment, muskeg, peat, geotextile, settlement, analysis, finite element, shear strength, soil reinforcement.
Pile group elastic load response prediction: friction piles embedded in cohesive soils
Authors: Douglas R. A. , Butterfield R.
Published: May 2009

Predicting the elastic vertical working load response of friction pile groups embedded in cohesive soils is a problem still requiring a solution that can be easily implemented by practising engineers. A design procedure based on an extensive analysis of the results of a computer program is presented as a solution to the problem.The program was used to study the effects of the interaction of closely spaced piles in groups, on the pile group response to loading. It is possible to define an average pile stiffness (load per unit displacement) and discuss a reduction of this stiffness, due to pile interaction, when the pile is placed in a group of similar piles. This interaction is accounted for by a stiffness reduction factor, ρ.The design approach is compared with load tests at model and full scale, with good agreement. Key words: piles, pile groups, working loads, elastic pile displacements.
LARGE-ASPECT RATIO MHD EQUATIONS FOR TOROIDAL PLASMAS
Authors: ASIF M.
Published: May 2009

A set of reduced MHD equations is derived using the equation of state including plasma compressibility. By applying assumption of pressure, i.e., R2P = const. , a set of reduced magnetohydrodynamic equations for toroidal plasmas are obtained for large aspect ratio, high β tokamaks. These equations include all terms of the same order as the toroidal effect and only involve three variables, namely the flux, stream function and pressure.
COHERENCE RESONANCE OF A JOSEPHSON JUNCTION EQUATION IN A BISTABLE REGION
Authors: ZHANG XUE-JUAN , ZHAO YANG
Published: May 2009

In this paper, the effect of noise in an underdamped Josephson junction equation without a periodic driving is numerically investigated. Two distinct phenomena of coherence resonance are observed by adjusting the damping coefficient and the sloping degree of the tilted periodic potential.
TOPOLOGICAL STRUCTURE OF VORTEX LINES OF QUANTUM ELECTRON PLASMAS IN THREE-DIMENSIONAL SPACE
Authors: SHI XUGUANG , DUAN YISHI
Published: May 2009

The topological properties of quantum electron plasmas in three-dimensional space are presented. Starting from ϕ-mapping topological current theory, the vortex lines are just at the core of wave function obtained. It is shown that the vorticity of the vortex can be expressed by the Hopf index and the Brouwer degree. We find that the vortex lines are unstable in some conditions and the evolution of vortex lines at the bifurcation points is given.
A FURTHER UNDERSTANDING OF PHASE SPACE PARTITION DIAGRAMS
Authors: THOMAS R. , NARDONE P.
Published: May 2009

This paper deals with dynamic systems described by sets of ordinary differential equations. As described in a previous paper [Thomas & Kaufman, 2005], phase space can be partitioned according to the signs of the eigenvalues of the Jacobian matrix and the slopes of its eigenvectors, using "frontiers" described by simple analytic expressions.

In the present paper, we develop this approach with special emphasis on:

— a preliminary, qualitative, yet quite efficient, description based simply on the sign patterns of elements of the Jacobian matrix

— the identification and characterization of two additional frontiers based on the relative slopes of the eigenvectors (in two dimensions only)

— the applicability to systems of higher dimensionalities

— programs (in Mathematica) that provide immediately the phase space frontier diagrams from the ODE's for two- (Appendix 2) and n-dimensional systems (Appendix 3)

For systems of sufficiently low dimensionality, the resulting diagrams give a global view of the structure of phase space, partitioned into domains each consistent as regards to the nature of any steady state that might be present in that domain. Fortunately, the dimensionality of phase space frontier diagrams depends not on the overall dimensionality of the system but on the number of variables that carry nonlinearity; an n-variable system in which only two variables carry nonlinearity can be described by a two-dimensional diagram.
EXISTENCE AND GLOBAL EXPONENTIAL STABILITY OF PERIODIC SOLUTION OF CELLULAR NEURAL NETWORKS WITH IMPULSES AND LEAKAGE DELAY
Authors: WANG HUI , LI CHUANDONG , XU HONGBING
Published: May 2009

This paper investigates the global periodicity of cellular neural network with impulses and leakage delay (i.e. with delay state feedback instead of instantaneous state feedback). Several conditions guaranteeing the existence, uniqueness, and global exponential stability of periodic solution are derived by using the continuation theorem of coincidence degree theory and a suitable degenerate Lyapuniv—Krasvovskii functional together with model transformation technique.
MEMORY PATTERN ANALYSIS OF BAM NEURAL NETWORKS WITH TIME-DELAY
Authors: KE YUNQUAN , MIAO CHUN-FANG
Published: May 2009

In this paper, memory patterns of bidirectional associative memory (BAM) neural networks with time-delay are investigated based on stability theory. Several sufficient conditions are obtained such that the equilibrium point is locally exponentially stable when the point is located at the designated position. These conditions, which can be directly derived from the synaptic connection weights and the external input of the BAM neural networks, are very easy to be verified. In addition, three examples are given to show the effectiveness of the results.
STABILITY OF BIFURCATED PERIODIC SOLUTIONS IN A DELAYED COMPETITION SYSTEM WITH DIFFUSION EFFECTS
Authors: YAN XIANG-PING , LI WAN-TONG
Published: May 2009

In this paper, a delayed Lotka—Volterra two species competition diffusion system with a single discrete delay and subject to the homogeneous Dirichlet boundary conditions is considered. By applying the normal form theory and the center manifold reduction for partial functional differential equations (PFDEs), the stability of bifurcated periodic solutions occurring through Hopf bifurcations is studied. It is shown that the bifurcated periodic solution occurring at the first bifurcation point is orbitally asymptotically stable on the center manifold while those occurring at other bifurcation points are unstable. Finally, some numerical simulations to a special example are included to verify our theoretical predictions.
RECURRENCE QUANTIFICATION ANALYSIS OF BOREHOLE TEMPERATURES: EVIDENCE OF FLUID CONVECTION
Authors: CERMAK VLADIMIR
Published: May 2009

To describe intra-hole fluid convection, fine-scale temperature-time variations were monitored at 25 depth levels within a 50 m long interval (80—130 m depth) in a slim experimental borehole in Sporilov (the Czech Republic). High-resolution temperature data were sampled with a 15 sec time interval for 1.6 up to 2.7 days. The time series obtained were from 10 000 to 16 000 data points. In the upper part of the investigated depth interval, the temperature time series showed a complex oscillation pattern with amplitudes of up to 45 mK (milliKelvin). This variation pattern is alternated with a "quiet" regime below 110 m depth, where temperature oscillations fall within 4–10 mK range.

Convection produced temperature signal was studied by means of recurrence plots and their quantification analysis. This method was proven to be effective to detect transitions in system dynamics. The analysis confirmed a relevant deterministic part in the measured signal (quasi-periodic skeleton) and enabled to quantify the periodic—periodic and periodic—chaotic transitions in the borehole convection dynamics. Thermal dynamics is richer and cooler at shallower depths. The results were confirmed with temperature time series registered at the bottom hole, where the probe penetrated into soft mud debris, which prevented convection, and restricted heat transport to a pure conduction.
CHAOTIC MOTION AND HAMILTONIAN DYNAMICS OF A PRESTRESSED INCOMPRESSIBLE ELASTIC PLATE DUE TO RESONANT-TRIAD INTERACTIONS
Authors: LI JIBIN , FU YIBIN , CHEN FENGJUAN
Published: May 2009

It has previously been established that in a prestressed incompressible elastic plate, a near-critical instability mode can interact resonantly with two non-critical vibration modes and that the evolution equations for the three modes take the form d2 A1/dτ2 = -c0A1 - c1|A1|2A1 - γ1Ā2Ā3, dA2/dτ = γ2Ā1Ā3 and dA3/dτ = γ3Ā1Ā2, where a bar denotes complex conjugation, τ is a slow time variable and c0, c1, γ1, γ2, γ3 are real constants. In this paper, we analyze these amplitude equations using dynamical systems theory. Regions of the parametric space that correspond to bounded solutions are determined and some explicit representations of the bounded solutions are obtained. It is shown that the resonant-triad interaction can lead to chaotic motions.