bluuebunny/crossref_metadata_2025 huggingface dataset:
The Denholm landslide, Saskatchewan. Part II: analysis
Authors: Sauer E. Karl
Published: July 2008

A procedure incorporating geological evidence with analytical methods was developed for the back analysis of a multiple retrogressive landslide in Cretaceous clay shale. The slide mass, apparently inactive, extends 2 km back from the toe at the river and is seated on a shear zone 100 m deep at the main scarp. Historical evidence of the slope movement was established from radiocarbon dating of the river alluvium over which the landslide moved. The geometry of the landslide when the factor of safety was near unity was determined from historic and stratigraphic evidence and sensitivity analyses.The stratigraphy of the slide mass showed that the beds are stretched with very little vertical displacement, indicating a mainly translational mechanism along a nearly horizontal shear zone. Apparently movement has taken place at a slow but steady rate over 11 000 years, resulting in a horizontal displacement of 390–430 m at the toe. The landslide, therefore, was analyzed as a series of sliding blocks with a common failure surface retrogressing from the toe up to the scarp. Each successive block was combined and considered to be moving as a single unit. Unknown factors, such as pore-water pressure at failure and the influence of cohesion, were evaluated by sensitivity analyses. The effective angle of shearing resistance required for limiting equilibrium was relatively constant, ranging from 7.6 to 8.7°, assuming the water table to be near the ground surface. For a lower water table, the values ranged from 6.5 to 8.0°. The equivalent values of cohesion required for equilibrium with [Formula: see text] ranged from 42 to 82 kPa depending on the size of the block, suggesting that c′ must be zero for the retrogressive mechanism analyzed by combining successive blocks. Keywords: slope stability, multiple-block, back analysis, residual strength, sensitivity analysis.
Frost heave – pipeline interaction using continuum mechanics
Authors: Nixon J. F. , Morgenstern N. R. , Reesor S. N.
Published: July 2008

As a chilled pipeline crosses a transition from frozen to unfrozen ground or shallow permafrost, a differential frost heave problem may develop causing strains in the pipe. Soil–structure interaction models that are currently available to handle this problem concentrate on the pipe as the dominant structural member and represent the soil mass as a series of unconnected springs. This paper considers the soil to be an elastic or nonlinear viscous continuum and imposes a nonlinear boundary condition to represent the frost heaving soil and the dependence of frost heave on applied pressure. The pipe is assumed to be a completely passive structural member and the soil strains at the pipe elevations are studied. The dependence of the maximum pipe strains on the length of the heaving section and on the thickness of frozen ground beneath the pipe have been established for a typical set of soil and frost heaving conditions. It is found that, for the conditions studied, when the thickness of shallow permafrost or frozen soil is greater than about 7–8 m, the strains that a flexible pipe experiences are less than the strain criteria currently in use on many pipeline projects. Keywords: frost heave, pipeline, interaction, stress analysis, finite elements, continuum mechanics, thermo-elasticity.
Influence of the in-situ stress field and joint stiffness on rock wedge stability in underground openings
Authors: Crawford A. M. , Bray J. W.
Published: July 2008

Rock wedges in the roofs of underground excavations may be wholly or partly self-supporting due to the mobilization of shear resistance on discontinuities bounding such wedges. The extent of the mobilization, which occurs as the wedge deforms, is markedly influenced by the magnitude of the stress field tangential to the opening and the relative stiffness of the intact rock and the shear and normal stiffnesses of the discontinuities. Analytical and numerical models are described for determining the upper and lower bounds of the failure loads for two-dimensional asymmetric and symmetric rock wedges. Experiments conducted on physical models indicate that the stability of rock wedges may be substantially reduced by loosening and that the analytical solutions may overestimate the load necessary to cause failure. Keywords: rock wedge stability, in situ stresses, joint stiffness.
Pile load tests for the Calgary Air Terminal building
Authors: Bertok J. , Berezowski M.
Published: July 2008

This technical note describes a case history of pile load tests for the Calgary Air Terminal building. One drilled, cast-in-place, concrete caisson, socketed into bedrock, and compacted expanded-base concrete piles were tested and evaluated to select a pile type that would support column loads up to 6700 kN. This note describes the pile test program, interprets the load test results, and summarizes the pile specifications and installation. Keywords: building foundation, piles, load testing, interpretation, installation.
Change in pore size distribution owing to secondary consolidation of clays
Authors: Griffiths Fred J. , Joshi Ramesh C.
Published: July 2008

The preliminary results of a study using mercury-intrusion porosimetry on freeze-dried samples of clayey soils are presented. The amount of secondary consolidation has been varied for several samples of three soil types by holding the consolidation stress steady at 120 kPa for different durations. Examination of the pore size distribution curves reveals that secondary consolidation cannot be due solely to the deformation of micropores. The relative degree of change in total, free and entrapped porosity appears to be related to the proportion of each initially in the sample. Key words: clays, consolidation, compressibility, fabric-structure of soils, secondary compression.
Electroosmotic strengthening of soft sensitive clays
Authors: Lo K. Y. , Inculet I. I. , Ho K. S.
Published: July 2008

A comprehensive experimental investigation on the electroosmotic strengthening of soft sensitive clay was performed to assess the effectiveness of the treatment and to study the mechanism of the process. A specially designed electroosmotic cell was developed to prevent gas accumulation near the electrodes, to allow better electrode-soil contact, and to improve the treatment efficiency. This apparatus also enables the monitoring of the generated negative pore-water pressure along the sample length, settlement, voltage distribution, and current variation during treatment. The investigation covered two different types of soil trimmed at different orientations: the vertically and horizontally trimmed overconsolidated Wallaceburg clay and the vertically trimmed slightly overconsolidated soft sensitive Gloucester (Leda) clay. Results of this study showed that the voltage distribution and induced negative pore pressure at equilibrium along the sample are linear with steady current flow across the sample, indicating that the electrode design in the electroosmosis test apparatus is efficient. The electroosmotic consolidation curve is similar to that of the conventional consolidation curve, and the preconsolidation pressure was increased by 51–88% with an applied voltage up to 6 V. The undrained shear strength increased to a maximum of 172%, and the moisture content decreased by 30%. The technique of electrode reversal is employed, and a relatively uniform strength increase between the electrodes is observed. Key words: electroosmosis, electroosmotic cell, soft sensitive clay, negative pore-water pressure, preconsolidation pressure, stress–strain behaviour.
Comparison of field consolidation with laboratory and in situ tests
Authors: Crawford C.B. , Campanella R. G.
Published: July 2008

Settlement calculations for an earth embankment resting on soft, compressible Fraser River Delta sediments were made from laboratory consolidation tests and in situ tests using a piezocone and a flat dilatometer. The calculated values were compared with measured settlements. There was rather good agreement among the three methods of calculation, but the actual settlement was about 60% greater than the average calculated value. Calculated rates of settlement are also compared with observed values. Key words: consolidation, settlements, piezocone, dilatometer, in situ tests, constrained modulus, pore-water pressure, settlement rate.
Design of bored piles in residual soils based on field-performance data
Authors: Chang M. F. , Broms B. B.
Published: July 2008

The current practice for the design of large-diameter bored piles in residual soils in Singapore is based on the calculated static capacity of the piles. Insufficient consideration of the load-transfer mechanism and overreliance on pile load tests have led to conservative designs. A better alternative is to adopt a load–displacement analysis method that provides information on the load distribution along the pile and the complete load–displacement relationship. Results of full-scale load tests on instrumented piles indicate that bored piles in residual soils in Singapore behave in the same way as in stiff clay and weak rocks elsewhere in that the load transfer at the working load is dominated by shaft friction. Simple correlations exist between the standard penetration resistance and the load-transfer parameters. An example illustrates that the proposed design procedure that uses these simple correlations and the load-transfer method is an improvement over present design methods. Key words: bored piles, cast-in-place piles, design, drilled piers, field test, load transfer, residual soil, shaft resistance.
Controlling the destructive effects of clay – organic liquid interactions, by application of effective stresses
Authors: Fernandez Federico , Quigley Robert M.
Published: July 2008

The magnitude of the effective stresses acting on a clay barrier appear to play a critical role in preserving low hydraulic conductivity, k, during exposure to soluble organic liquids. This paper summarizes the results of a research study on a natural clay from southwestern Ontario permeated with various mixtures of landfill leachate and water-soluble organic liquids at effective stresses ranging from 0 to ~300 kPa. Laboratory testing of "unconfined", water-compacted clays indicated that municipal solid waste leachates containing ethanol and dioxane at concentrations in excess of 70% can cause damaging increases in k of up to 1000-fold. Predamage application of vertical effective stresses can reduce or even eliminate these increases in k because of chemically induced consolidation and closure of macropores that develop as a result of double layer collapse. The levels of static effective stress required to prevent the increases in k were much higher for nonpolar dioxane (> 160 kPa) than for intermediately polar ethanol (20–40 kPa). Postdamage application of static effective stresses successfully eliminated the increases in k produced by ethanol permeation at near zero stress but could not heal the clay damaged by permeation of nonpolar dioxane. The practical significance of this work is discussed relative to clay barrier design. Key words: hydraulic conductivity, clay, organic liquids, leachate, liner, effective stress healing.
Comportement, en chambre triaxiale, d'un pieu à frottement dans l’argile
Authors: Roy Marius , Roy Sylvain , Dubé Jean
Published: July 2008

This study deals with the behaviour of a friction pile in a clay, in a triaxial chamber, and in particular with the generation of pore pressures during driving, and with the mobilization of lateral friction during loading tests at constant rate of penetration and static. The results show that the setting compares with that of a piezocone, and that the pore pressures generated at the point during driving, in the laboratory, are of the same order of magnitude as those obtained on the field. The conditions of reconsolidation used in the laboratory, which define the effective stresses around the pile, allow the calculation of the lateral friction on the model pile. The same conditions of reconsolidation were applied to the full-scale tests, on the Maskinongé site, and yielded values of angles of friction δ of 16° for steel and 20° for concrete. Key words: pile, clay, triaxial chamber, friction, pore pressure. [Journal translation]
Numerical simulations to investigate moisture-retention characteristics in the design of oxygen-limiting covers for reactive mine tailings
Authors: Akindunni Festus F. , Gillham R. W. , Nicholson R. V.
Published: July 2008

Acid generation in reactive mine tailings is an oxidation process that is dependent on availability of molecular oxygen. As a consequence of the diffusion coefficient of oxygen being several orders of magnitude higher in air than in water, influx of atmospheric oxygen into a material at depth can theoretically be minimized by maintaining a protective cover layer at high moisture content. Such oxygen-limiting covers are generally of finer texture than the material being protected. A numerical model was used to investigate the importance of moisture-retention characteristics in the transient drainage of such two-layer systems. The results show that the effectiveness of a material as a moisture-retaining cover is dependent on the magnitude of its air-entry value. The thickness of the cover maintained at full saturation after prolonged drainage also depends on the pressure head at which the underlying material approaches residual saturation. Key words: geologic covers, tailings, numerical simulations, air-entry value, residual saturation, textural layering.
Engineering behaviour of a low carbon, pozzolanic fly ash and its potential as a construction fill
Authors: Indraratna B. , Nutalaya P. , Koo K. S. , Kuganenthira N.
Published: July 2008

Detailed laboratory investigations were conducted on Mae Moh fly ash from northern Thailand for the determination of its grain size distribution, mineralogy, pozzolanic activity, compaction and strength characteristics, and the collapse potential. On the basis of the experimental results, this fly ash is classified as ASTM class C, which is considered to be pozzolanic. It has good potential to be utilized as an effective fill for embankments (roads and dams), airfields, pavements, and building bricks, as well as for the stabilization of compressible or erodible foundations. Because of the fact that Mae Moh fly ash contains only a negligible amount of unburned carbon, its pozzolanic reactivity is accelerated, in comparison with the relatively inert, high-carbon fly ash produced elsewhere in Thailand and many other parts of Asia. It is also demonstrated that Mae Moh fly ash can be easily compacted to produce acceptable dry densities over a wide range of water contents. Curing with an adequate moisture supply in the presence of calcium oxide plays an important role in accelerating the pozzolanic reactions, hence improving the time-dependent-properties. This study further proposes that a curing period of 2–3 weeks is sufficient for this material to approach its maximum strength. Although the behaviour of one specific fly ash cannot generalize the wide array of other ashes, the test results obtained for Mae Moh fly ash may be applied to lignite ashes in the category of ASTM class C. Key words: fly ash, structural fill, compaction, compressive strength, shear strength, collapse potential, pozzolanic activity.
Five-year monitoring of load losses on prestressed cement-grouted rock anchors
Authors: Benmokrane Brahim , Ballivy Gérard
Published: July 2008

The long-term study of the behaviour of prestressed grouted rock anchors constitutes an important aspect of the stability of the structure retained by these structural members. The loads supplied by the anchors must be sufficient so that at all times the stability of the structure is not compromised. The results of an experimental study of nine anchors grouted to various lengths with a cement grout, on site, in a sound rock mass are described. Tension was applied to the anchors which were then blocked at initial loads of about 80% of failure load. During 5 years, the load variations in each anchor were recorded with load cells. It was observed that the load variations versus time make up two phases: phase I, lasting about 6 months, throughout which the losses of load are rapid; and phase II, which is marked by a slower and uniform rate of load loss. In this experimental research, the instantaneous losses of load that occurred during the stressing and the lock-off operation also have been measured. The study shows that it is unnecessary to increase the anchored length to reduce long-term load losses. Key words: grouted rock anchor, prestressed anchor, cement grout, massive rock, load loss, creep, relaxation, long-term behaviour.
Permafrost and thermal interfaces from Normal Wells pipeline ditchwall logs
Authors: Nixon J. F. Derick , Saunders R. , Smith J.
Published: July 2008

During the construction of the Normal Wells pipeline by Interprovincial Pipeline Ltd. in the early 1980s, a continuous ditchwall log was created during ditching for pipeline burial. The ditch was typically 1.2 m deep and stretched continuously from Normal Wells in the Canadian Arctic to Zama Lake in northern Alberta, a total distance of 869 km through the discontinuous permafrost zone. The ditch was logged by experienced geotechnical field personnel every 50–100 m, depending on changing conditions. Every transition from unfrozen to frozen soil was logged based on visual criteria such as color change, visual presence of ice or moisture in the ditchwall, etc. Recently, the authors have carefully studied the ditchwall records and compiled a data file containing all of the relevant data pertaining to permafrost distribution. This provided a unique opportunity to study the amount and distribution of permafrost along a continuous transect through discontinuous and sporadic permafrost regions in Arctic Canada. The number of thermal interfaces per kilometre is an extremely important input parameter for studies relating to pipeline frost heave and thaw settlement in the Arctic. In addition, a knowledge of the percentage of frozen ground is important when deciding whether to operate a gas or pipeline above or below freezing. The number of frozen–unfrozen interfaces have been summarized in the paper by pipeline spread and geological terrain unit. The overall percentage of frozen ground decreases from up to 95% in the north to a low of around 16% at the south end of the study area, as might be expected. The number of interfaces typically varies between about one and three per kilometre, with the highest number occurring in some of the organic terrain units in the southern discontinuous zone. Finally, comparisons are made with the amount of permafrost and number of interfaces as logged by electrical geophysical surveys carried out and published in advance of pipeline construction. There is reasonable agreement in terms of the overall amount of frozen ground; however, the geophysical surveys may have overestimated the number of thermal interfaces in some areas. Key words: ditch logs, permafrost, Normal Wells, pipeline, thermal interfaces, frozen ground.
Dynamic deformation characteristics of undisturbed riverbed gravels
Authors: Yasuda N , Ohta N , Nakamura A
Published: July 2008

The strength and deformation characteristics of undisturbed specimens measured by large-scale triaxial tests were compared with those of reconstituted specimens to evaluate the stiffness of natural ground. The undisturbed specimens were sampled from the riverbed gravel foundation of an embankment dam using the freezing sampling method with liquid nitrogen. The validity of the results from the undisturbed specimens was evaluated by comparing the stiffness of the natural ground using P- and S-wave logging (PS logging). The dynamic deformation characteristics (stiffness) of undisturbed specimens are larger than those of reconstitued specimens.

Key words: shear modulus, damping ratio, gravel, laboratory test.
Calculated and observed behaviour of a reinforced embankment over soft compressible soil
Authors: Rowe R Kerry , Gnanendran C T , Landva A O , Valsangkar A J
Published: July 2008

The finite element analysis of an instrumented geotextile-reinforced test embankment is described and the results are compared with the field measurements. The embankment was constructed to failure on a soft compressible organic clayey silt deposit at Sackville, New Brunswick. The analysis adopts a fully coupled large-strain elasto-plastic Biot consolidation model with modified Cam-clay material behaviour. It is shown that the analysis captured many features of the embankment behaviour. However, it is concluded that the elasto-plastic modified Cam-clay formulation is not adequate for accurately and simultaneously predicting the multiple characteristics (e.g., vertical and horizontal deformations, pore pressures, and geotextile strains) of the embankment behaviour, primarily because of the rate sensitive nature, and the consequent progressive failure of the foundation soil.

Key words: embankment, geotextile, reinforcement, analysis, field behaviour, deformations.
The role of convergence measurements in characterizing a rock mass
Authors: Martin C Derek , Chandler Neil A , Read Rodney S
Published: July 2008

Convergence measurements were taken during the construction of a circular shaft in massive granite. The convergence results were used to back-calculate the in situ horizontal stress orientation and magnitudes. The results from the convergence method were supported by other measurement techniques and numerical modelling.

Key words: convergence, in situ stress, back-analysis.
Bregman bubble clustering
Authors: Gupta Gunjan , Ghosh Joydeep
Published: July 2008

In classical clustering, each data point is assigned to at least one cluster. However, in many applications only a small subset of the available data is relevant for the problem and the rest needs to be ignored in order to obtain good clusters. Certain nonparametric density-based clustering methods find the most relevant data as multiple dense regions, but such methods are generally limited to low-dimensional data and do not scale well to large, high-dimensional datasets. Also, they use a specific notion of “distance”, typically Euclidean or Mahalanobis distance, which further limits their applicability. On the other hand, the recent One Class Information Bottleneck (OC-IB) method is fast and works on a large class of distortion measures known as Bregman Divergences, but can only find a
single
dense region. This article presents a broad framework for finding
k
dense clusters while ignoring the rest of the data. It includes a seeding algorithm that can automatically determine a suitable value for
k
. When
k
is forced to 1, our method gives rise to an improved version of OC-IB with optimality guarantees. We provide a generative model that yields the proposed iterative algorithm for finding
k
dense regions as a special case. Our analysis reveals an interesting and novel connection between the problem of finding dense regions and exponential mixture models; a hard model corresponding to
k
exponential mixtures with a uniform background results in a set of
k
dense clusters. The proposed method describes a highly scalable algorithm for finding multiple dense regions that works with any Bregman Divergence, thus extending density based clustering to a variety of non-Euclidean problems not addressable by earlier methods. We present empirical results on three artificial, two microarray and one text dataset to show the relevance and effectiveness of our methods.
Entropy metric for XML DTD documents
Authors: Basci Dilek , Misra Sanjay
Published: July 2008

The eXtensible Markup Language (XML) has been gaining extraordinary acceptance from many diverse enterprise software companies for their object repositories, data interchange, and development tools. Further, many different domains, organizations and content providers have been publishing and exchanging information via internet by the usage of XML and standard schemas. Efficient implementation of XML in these domains requires well designed XML schemas. In this point of view, design of XML schemas plays an extremely important role in software development process and needs to be quantified for ease of maintainability. In this paper, we propose a new metric based on the entropy concept from information theory for the assessment of the structural complexity of XML schema documents written in W3C Document Type Definition (DTD), language. The new metric has been demonstrated with examples and supported by comparison with the other well known structure metrics applied on XML schema documents.
Test case prioritization based on requirements and risk factors
Authors: Srivastva Praveen Ranjan , Kumar Krishan , Raghurama G
Published: July 2008

To test software products effectively, large number of test cases are designed. But it is nearly impossible to execute all the tests due to tight time constraints and some other reasons such as availability of experts etc. Due to these reasons, the necessity of reducing the number of test cases comes into existence. Test case prioritization helps to reduce the number of test cases. This paper presents an approach that focuses on prioritizing the test cases. Proposed approach prioritizes test cases on the basis of requirements identified and risk factors that can occur in a software project.
Fluorescence Proteins, Live-Cell Imaging, and Mechanobiology: Seeing Is Believing
Authors: Wang Yingxiao , Shyy John Y.-J. , Chien Shu
Published: July 2008

Fluorescence proteins (FPs) have been widely used for live-cell imaging in the past decade. This review summarizes the recent advances in FP development and imaging technologies using FPs to monitor molecular localization and activities and gene expressions in live cells. We also discuss the utilization of FPs to develop molecular biosensors and the principles and application of advanced technologies such as fluorescence resonance energy transfer (FRET), fluorescence recovery after photobleaching (FRAP), fluorescence lifetime imaging microscopy (FLIM), and chromophore-assisted light inactivation (CALI). We present examples of the application of FPs and biosensors to visualize mechanotransduction events with high spatiotemporal resolutions in live cells. These live-cell imaging technologies, which represent a frontier area in biomedical engineering, can shed new light on the mechanisms regulating mechanobiology at cellular and molecular levels in normal and pathophysiological conditions.
Current and Future Considerations in the Use of Mechanical Circulatory Support Devices
Authors: Simon Marc A. , Watson John , Baldwin J. Timothy , Wagner William R. , Borovetz Harvey S.
Published: July 2008

Heart failure (HF) is a major public health problem in the United States, and its prevalence is likely to increase with the aging U.S. population. Mechanical circulatory support (MCS) utilizing bladder-based blood pumps generating pulsatile flow has been reserved for patients with severe HF failing medical therapy. As MCS technology has advanced to include rotary blood pumps, so has our understanding of the biological and clinical responses to MCS, which in turn has altered the risk/benefit profile of this therapy. This may lead to paradigm shifts in device usage from support of end-stage HF to temporary support for recovery of cardiac function and earlier usage, to, ultimately, prevention of disease progression. This review serves to explore the current state and future opportunities of MCS within our larger understanding of the epidemiology, pathophysiology, and treatment options for HF.
Light Emitting Diodes of Inverse Spin Valves
Authors: Wang X. R.
Published: July 2008

Light emitting diodes made out of inverse spin valves of a ferromagnetic half metal
sandwiched between two nonmagnetic metals are proposed. Based on a giant spin‐dependent
chemical potential difference created under an external bias, the inverse spin valves are possible to emit light when electrons with the higher chemical potential flip their spins and become the electrons of the opposite spin with the lower chemical potential. The frequency of this type of light emitting diodes is tunable by
the bias.
The Outcome of Surgery versus Medical Management in the Treatment of Vesicoureteral Reflux
Authors: Nelson Caleb P.
Published: July 2008

Evaluation of the relative merits of medical versus surgical management of vesicoureteral reflux (VUR) has been limited by the few prospective studies comparing these strategies. Among those trials that have been reported, the only consistent positive finding has been that incidence of febrile UTI is lower among children undergoing surgical treatment in comparison with medical treatment. Studies have not found significant differences in overall incidence of UTI, or in rates of new renal scarring or progression of existing scarring. It is likely that there is a subset of children with VUR who do benefit from aggressive treatment of their VUR, but we are not yet able to fully determine which children these are. It is hoped that future research will further clarify which treatments are useful in which children.
Do the Changes in the Serum Levels of IL-2, IL-4, TNFα, and IL-6 Reflect the Inflammatory Activity in the Patients with Post-ERCP Pancreatitis?
Authors: Kilciler Guldem , Musabak Ugur , Bagci Sait , Yesilova Zeki , Tuzun Ahmet , Uygun Ahmet , Gulsen Mustafa , Oren Sema , Oktenli Cagatay , Karaeren Necmettin
Published: July 2008

Background. Acute pancreatitis is the major complication of endoscopic retrograde cholangiopancreatography (ERCP) procedure and there are some reports showing cytokine changes in ERCP-induced pancreatits.Goals. To investigate the association between early changes (within 24 hours) in the serum interleukin (IL)-2, IL-4, tumor necrosis factor (TNF)α, and IL-6 levels and the development of post-ERCP pancreatitis.Study. Forty five consecutive patients who underwent therapeutic ERCP and 10 patients with acute pancreatitis without ERCP were enrolled to the study. Serum concentrations of IL-2, IL-4, TNFα, and IL-6 were determined immediately before, 12 hours and 24 hours after ERCP.Results. Seven of the 45 patients (15.5%) developed post-ERCP pancreatitis. The levels of IL-4 at 24 hours after ERCP were significantly lower in the patients with post-ERCP pancreatitis than in those without pancreatitis, while TNFαlevels at 12 hours after ERCP were higher in the complicated group than those of the uncomplicated group. The ratios of TNFα/IL-4 at 12 and 24 hours after ERCP were found significantly higher in the patients with post-ERCP pancreatitis than in those without pancreatitis. IL-6 in the complicated patients was found significantly increased at 24 hours after ERCP.Conclusions. The enhancement of serum TNFαand IL-6 levels in the patients with ERCP-induced pancreatitis reflects the inflammatory activity. Additionally, these cytokines together with IL-4 can be used in clinical laboratory monitoring of ERCP.
Discrete‐Time Sliding‐Mode Control of Uncertain Systems with Time‐Varying Delays via Descriptor Approach
Authors: Yan Maode , Mehr Aryan Saadat , Shi Yang
Published: July 2008

This paper considers the problem of robust discrete‐time sliding‐mode control (DT‐SMC)
design for a class of uncertain linear systems with time‐varying delays. By applying a descriptor
model transformation and Moon′s inequality for bounding cross terms, a delay‐dependent
sufficient condition for the existence of stable sliding surface is given in terms of linear matrix
inequalities (LMIs). Based on this existence condition, the synthesized sliding mode controller
can guarantee the sliding‐mode reaching condition of the specified discrete‐time sliding surface
for all admissible uncertainties and time‐varying delays. An illustrative example verifies the
effectiveness of the proposed method.
Vesicoureteral Reflux, Reflux Nephropathy, and End-Stage Renal Disease
Authors: Brakeman Paul
Published: July 2008

Objective. To review the contribution of vesicoureteral reflux and reflux nephropathy to end-stage renal disease.Data Source. Published research articles and publicly available registries.Results. Vesicoureteral reflux (VUR) is commonly identified in pediatric patients and can be associated with reflux nephropathy (RN), chronic kidney disease (CKD), and rarely end-stage renal disease (ESRD). Patients with reduced GFR, bilateral disease, grade V VUR, proteinuria, and hypertension are more likely to progress to CKD and ESRD. Because progression to ESRD is rare in VUR and often requires many decades to develop, there are limited prospective, randomized, controlled trials available to direct therapy to prevent progression to ESRD.Conclusions. Identification of patients with increased risk of progression to CKD and ESRD should be the goal of clinical, biochemical, and radiological evaluation of patients with VUR. Treatment of patients with VUR should be directed at preventing new renal injury and preserving renal function.
The Amphiphilic Self‐Assembling Peptide EAK16‐I as a Potential Hydrophobic Drug Carrier
Authors: Wang Jing , Tang Fushan , Li Feng , Lin Juan , Zhang Yinghui , Du Linfang , Zhao Xiaojun
Published: July 2008

It is crucial for hydrophobic drugs to be dissolved and stabilized by carriers in aqueous systems and then to be delivered into target cells. An amphiphilic self‐assembling peptide EAK16‐I (Ac‐AEAKAEAKAEAKAEAK‐NH2) is reported here to be able to stabilize a model hydrophobic compound, pyrene, in aqueous solution, resulting in the formation of colloidal suspensions. Egg phosphatidylcholine (EPC) vesicles are used as plasma membranes mimic. Fluorescence data shows that the pyrene is presented in the crystalline form when stabilized by EAK16‐I and molecularly migrates from its peptide encapsulations into the membrane bilayers of EPC vesicles when the suspension is mixed with EPC vesicles. Furthermore, the release rate can be controlled by changing peptide‐to‐pyrene ratio, and the higher ratios lead to the slower release rates due to a thicker encapsulation on the pyrene microcrystals. This demonstrates that EAK16‐I, as a promising nanobiomaterial, has the potential to be a hydrophobic compounds carrier.
Existence and Global Asymptotical Stability of Periodic Solution for the T‐Periodic logistic System with Time‐Varying Generating Operators and T0‐Periodic Impulsive Perturbations on Banach Spaces
Authors: Wang JinRong , Xiang X. , Wei W. , Chen Qian
Published: July 2008

This paper studies the existence and global asymptotical stability of periodic PC‐mild solution for
the T‐periodic Logistic system with time‐varying generating operators and T0‐periodic impulsive perturbations on
Banach spaces. Two sufficient conditions that guarantee the exponential stability of the impulsive evolution operator
corresponding to homogenous well‐posed T‐periodic system with time‐varying generating operators and T0‐periodic
impulsive perturbations are given. It is shown that the system have a unique periodic PC‐mild solution which is globally asymptotically stable when T and T0 are rational dependent and its period must be nT0 for some n ∈ N. At last, an example is given for demonstration.
Textural Classification of Mammographic Parenchymal Patterns with the SONNET Selforganizing Neural Network
Authors: Howard Daniel , Roberts Simon C. , Ryan Conor , Brezulianu Adrian
Published: July 2008

In nationwide mammography screening, thousands of mammography examinations must be processed. Each consists of two standard views of each breast, and each mammogram must be visually examined by an experienced radiologist to assess it for any anomalies. The ability to detect an anomaly in mammographic texture is important to successful outcomes in mammography screening and, in this study, a large number of mammograms were digitized with a highly accurate scanner; and textural features were derived from the mammograms as input data to a SONNET selforganizing neural network. The paper discusses how SONNET was used to produce a taxonomic organization of the mammography archive in an unsupervised manner. This process is subject to certain choices of SONNET parameters, in these numerical experiments using the craniocaudal view, and typically produced O(10), for example, 39 mammogram classes, by analysis of features from O(103) mammogram images. The mammogram taxonomy captured typical subtleties to discriminate mammograms, and it is submitted that this may be exploited to aid the detection of mammographic anomalies, for example, by acting as a preprocessing stage to simplify the task for a computational detection scheme, or by ordering mammography examinations by mammogram taxonomic class prior to screening in order to encourage more successful visual examination during screening. The resulting taxonomy may help train screening radiologists and conceivably help to settle legal cases concerning a mammography screening examination because the taxonomy can reveal the frequency of mammographic patterns in a population.
Predicting the Onset of Cavitation in Automotive Torque Converters—Part I: Designs with Geometric Similitude
Authors: Robinette D. L. , Schweitzer J. M. , Maddock D. G. , Anderson C. L. , Blough J. R. , Johnson M. A.
Published: July 2008

Dimensional analysis has been applied to automotive torque converters to understand the response of performance to changes in torque, size, working fluid, or operating temperature. The objective of this investigation was to develop a suitable dimensional analysis for estimating the effect of exact geometric scaling of a particular torque converter design on the onset of cavitation. Torque converter operating thresholds for cavitation were determined experimentally with a dynamometer test cell at the stall operating condition using nearfield acoustical measurements. Dimensionless quantities based upon either speed or torque at the onset of cavitation and flow properties (e.g., pressures and temperature dependent fluid properties) were developed and compared. The proposed dimensionless stator torque quantity was found to be the most appropriate scaling law for extrapolating cavitation thresholds to multiple diameters. A power product model was fit on dimensionless stator torque data to create a model capable of predicting cavitation thresholds. Comparison of the model to test data taken over a range of operating points showed an error of 3.7%. This is the first paper of a two‐part paper. In Part II, application of dimensional analysis will be expanded from torque converters with exact geometric similitude to those of more general design.
Postsynaptic Signals Mediating Induction of Long-Term Synaptic Depression in the Entorhinal Cortex
Authors: Kourrich Saïd , Glasgow Stephen D. , Caruana Douglas A. , Chapman C. Andrew
Published: July 2008

The entorhinal cortex receives a large projection from the piriform cortex, and synaptic plasticity in this pathway may affect olfactory processing. In vitro whole cell recordings have been used here to investigate postsynaptic signalling mechanisms that mediate the induction of long-term synaptic depression (LTD) in layer II entorhinal cortex cells. To induce LTD, pairs of pulses, using a 30-millisecond interval, were delivered at 1 Hz for 15 minutes. Induction of LTD was blocked by the NMDA receptor antagonist APV and by the calcium chelator BAPTA, consistent with a requirement for calcium influx via NMDA receptors. Induction of LTD was blocked when the FK506 was included in the intracellular solution to block the phosphatase calcineurin. Okadaic acid, which blocks activation of protein phosphatases 1 and 2a, also prevented LTD. Activation of protein phosphatases following calcium influx therefore contributes to induction of LTD in layer II of the entorhinal cortex.
Chemopreventive Doses of Methylselenocysteine Alter Circadian Rhythm in Rat Mammary Tissue
Authors: Zhang Xun , Zarbl Helmut
Published: July 2008

It is known that organic forms of selenium inhibit chemically induced rat mammary carcinogenesis, although the molecular basis remains to be elucidated. To identify signaling pathways involved in carcinogenesis that are also modulated by methylselenocysteine, we compared the global gene expression profiles in mammary tissues from pubescent female rats maintained on a selenium-supplemented (3 ppm) diet with those on a standardized diet after N-nitroso-N-methylurea. Whereas the selenium-enriched diet altered the steady-state levels of genes involved in various cellular functions, the most dramatic effect was the coordinated changes in the expression of multiple genes that regulate circadian rhythm. Normal mammary tissue of rats fed a standardized diet showed little circadian oscillation relative to liver tissue. By contrast, mammary tissue of rats maintained on the selenium-enriched diet showed a progressive, time-dependent increase in the expression of circadian gene Per2 and circadian-regulated transcription factor DBP. Our results further showed that the expression of Per2 and DBP mRNAs was significantly decreased in mammary tumors arising in rats on the selenium-enriched diet, but not in tumors of rats on the control diet, suggesting that selenium-induced elevation in the expression of circadian genes was incompatible with mammary carcinogenesis. Given the previously reported role of Per2 as a tumor suppressor, these observations suggest that Per2 is an important target of methylselenocysteine during chemoprevention in N-nitroso-N-methylurea–induced rat mammary carcinogenesis, and for the first time provide a link between chemoprevention and circadian rhythm.
Oral Epithelium as a Surrogate Tissue for Assessing Smoking-Induced Molecular Alterations in the Lungs
Authors: Bhutani Manisha , Pathak Ashutosh Kumar , Fan You-Hong , Liu Diane D. , Lee J. Jack , Tang Hongli , Kurie Jonathan M. , Morice Rodolfo C. , Kim Edward S. , Hong Waun Ki , Mao Li
Published: July 2008

The lungs and oral cavity of smokers are exposed to tobacco carcinogens. We hypothesized that tobacco-induced molecular alterations in the oral epithelium are similar to those in the lungs, and thus the oral epithelium may be used as a surrogate tissue for assessing alterations in the lungs. We used methylation-specific PCR to analyze promoter methylation of the p16 and FHIT genes at baseline and 3 months after intervention in 1,774 oral and bronchial brush specimens from 127 smokers enrolled in a randomized placebo-controlled chemoprevention trial. The association between methylation patterns in oral tissues and bronchial methylation indices (methylated sites / total sites per subject) was analyzed in a blinded fashion. At baseline, promoter methylation in bronchial tissue was present in 23% of samples for p16, 17% for FHIT, and 35% for p16 and FHIT; these percentages were comparable to methylation in oral tissue: 19% (p16), 15% (FHIT), and 31% (p16 and FHIT). Data from both oral and bronchial tissues were available for 125 individuals, in whom the two sites correlated strongly with respect to alterations (P < 0.0001 for both p16 and FHIT). At baseline, the mean bronchial methylation index was far higher in patients with oral tissue methylation (in either of the two genes; 39 patients) than in patients without oral tissue methylation (86 patients): 0.53 ± 0.29 versus 0.27 + 0.26 methylation index (P < 0.0001). Similar correlations occurred at 3 months after intervention. Our results support the potential of oral epithelium as a surrogate tissue for assessing tobacco-induced molecular damage in the lungs and thus have important implications for designing future lung cancer prevention trials and for research into the risk and early detection of lung cancer.
Prevalence and Prognostic Significance of Preprocedural Cardiac Troponin Elevation Among Patients With Stable Coronary Artery Disease Undergoing Percutaneous Coronary Intervention
Authors: Jeremias Allen , Kleiman Neal S. , Nassif Deborah , Hsieh Wen-Hua , Pencina Michael , Maresh Kelly , Parikh Manish , Cutlip Donald E. , Waksman Ron , Goldberg Steven , Berger Peter B. , Cohen David J.
Published: July 2008

Background—

Although cardiac troponin (cTn) elevation is associated with periprocedural complications during percutaneous coronary intervention (PCI) in the setting of acute coronary syndromes, the prevalence and prognostic significance of preprocedural cTn elevation among patients with stable coronary artery disease undergoing PCI are unknown.

Methods and Results—

Between July 2004 and September 2006, 7592 consecutive patients who underwent attempted stent placement at 47 hospitals throughout the United States were enrolled in a prospective multicenter registry. We analyzed the frequency of an elevated cTn immediately before PCI and its relationship to in-hospital and 1-year outcomes among patients who underwent PCI for either stable angina or a positive stress test. Among the stable coronary artery disease population (n=2382, 31.4%), 142 (6.0%) had a cTn level above the upper limit of normal before the procedure. Compared with patients who had normal baseline cTn, patients with elevated cTn had a higher rate of in-hospital death or myocardial infarction (13.4% versus 5.6%;
P
<0.001) and a trend toward higher rates of urgent repeat PCI (1.4% versus 0.2%;
P
=0.06). In multivariable analyses adjusted for demographic, clinical, angiographic, and procedural factors, baseline cTn elevation remained independently associated with the composite of death or myocardial infarction at hospital discharge (odds ratio, 2.1; 95% confidence interval, 1.2 to 3.8;
P
=0.01) and at the 1-year follow-up (odds ratio, 2.0; 95% confidence interval, 1.2 to 3.3;
P
=0.005).

Conclusions—

Baseline elevation of cTn is relatively common among patients with stable coronary artery disease undergoing PCI and is an independent prognostic indicator of ischemic complications. If these data are confirmed in future studies, consideration should be given to routine testing of cTn before performance of PCI in this patient population.
Corticosteroids for Recurrent Pericarditis
Authors: Imazio Massimo , Brucato Antonio , Cumetti Davide , Brambilla Giovanni , Demichelis Brunella , Ferro Silvia , Maestroni Silvia , Cecchi Enrico , Belli Riccardo , Palmieri Giancarlo , Trinchero Rita
Published: July 2008

Background—

Corticosteroid use is widespread in recurrent pericarditis, even if rarely indicated, and high doses (eg, prednisone 1.0 to 1.5 mg · kg
−1
· d
−1
) are generally recommended, although only weak evidence supports their use with possible severe side effects. The aim of this work was to compare side effects, recurrences and other complications, and hospitalizations of a low- versus high-dose regimen of prednisone for recurrent pericarditis.

Methods and Results—

A retrospective review of all cases of recurrent pericarditis treated with corticosteroids according to different regimens from January 1996 to June 2004 was performed in 2 Italian referral centers. One hundred patients with recurrent pericarditis (mean age, 50.1±15.8 years; 57 females) were included in the study; 49 patients (mean age, 47.5±16.0; 25 females) were treated with low doses of prednisone (0.2 to 0.5 mg · kg
−1
· d
−1
), and 51 patients (mean age, 52.6±15.3; 32 females) were treated with prednisone 1.0 mg · kg
−1
· d
−1
. Baseline demographic and clinical characteristics were well balanced across the groups. Each initial dose was maintained for 4 weeks and then slowly tapered. After adjustment for potential confounders (age, female gender, nonidiopathic origin), only high doses of prednisone were associated with severe side effects, recurrences, and hospitalizations (hazard ratio, 3.61; 95% confidence interval, 1.96 to 6.63;
P
<0.001).

Conclusions—

Use of higher doses of prednisone (1.0 mg · kg
−1
· d
−1
) for recurrent pericarditis is associated with more side effects, recurrences, and hospitalizations. Lower doses of prednisone should be considered when corticosteroids are needed to treat pericarditis.