bluuebunny/crossref_metadata_2025 huggingface dataset:
Nonlinear analysis of normal- and high-strength concrete slabs
Authors: Marzouk H. , Chen Z. W.
Published: January 2010

Concrete slabs supported on four edges and loaded axially and transversely are used in many civil engineering applications. High-strength concrete slabs are commonly used for marine structures and offshore platforms. The catastrophic nature of the failure exhibited by reinforced concrete slabs when subjected to concentrated loads has been a major concern for engineers over many years. Therefore, there is a great need to develop accurate numerical models suitable for normal-strength or high-strength concrete in order to reflect properly its structural behaviour.Proper simulation of the post-cracking behaviour of concrete has a significant effect on the nonlinear finite element response of such slabs. Cracking and post-cracking behaviour of concrete which includes aggregate interlock, dowel action, and tension-stiffening effects is especially crucial for any nonlinear concrete analysis. The post-cracking behaviour and the fracture energy properties of high-strength concrete are different from those of normal-strength concrete. This can be realized by comparing the experimental testing results of plain normal- and high-strength concrete. The experimental results of testing plain high-strength concrete in direct tension indicated that the total area under the stress - crack width curve in tension is different from that of normal-strength concrete.A suitable softening and tension-stiffening model is recommended for high-strength concrete; other existing models suitable for normal-strength concrete are discussed. The proposed post-cracking behaviour models are implemented in a nonlinear finite element program in order to check the validity of such models by comparing the actual experimental data with the finite element results. Finally, a parametric study was conducted to provide more insight into the behaviour of high-strength concrete slabs subjected to combined uniaxial in-plane loads and lateral loads. The effects of the magnitude of in-plane load and the sequence of loading on the structural behaviour of such slabs are examined. Key words: high-strength concrete, slabs, punching shear, fracture energy, tension-softening, tension-stiffening, parametric study.
Equivalent slenderness ratio for built-up members
Authors: Temple Murray C. , Elmahdy Ghada
Published: January 2010

Built-up struts that buckle about an axis perpendicular to the plane of the connectors should be treated as a "built-up" member as opposed to a "simple" member. This mode of buckling causes shear and moments in the connectors which deform the connectors. These deformations increase the lateral deformation of the member and hence affect the load-carrying capacity. To account for this effect the easiest method is to use an equivalent slenderness ratio such as the one included in the Canadian Standard. This note outlines the derivation of the equivalent slenderness ratio equation, discusses when it should and should not be used, and includes a numerical example. A rewording of the applicable clause in the Canadian Standard is suggested. Key words: battens, built-up members, connectors, slenderness ratio.
Enzyme catalyzed polymerization and precipitation of aromatic compounds from aqueous solution
Authors: Nicell J. A. , Bewtra J. K. , Biswas N. , St. Pierre C. C. , Taylor K. E.
Published: January 2010

Horseradish peroxidase enzyme (HRP), once activated by hydrogen peroxide, initiates the oxidation of a wide variety of aromatic compounds. Reaction products undergo a non-enzymatic polymerization to form water insoluble aggregates which are readily separated from solution. HRP was selected for application in wastewater treatment systems due to its stability and retention of its catalytic ability over wide ranges of pH and temperature. HRP activity was optimal between pH 5.7 and 8.5 with peak activity occurring at neutral pH. Activity increased with temperature up to 50 °C and declined at higher temperatures due to thermal inactivation. HRP was inactivated rapidly by hydrogen peroxide in the absence of an aromatic substrate. The efficiency of removal that was achieved was dependent on the nature of the aromatic undergoing treatment and the amount of enzyme provided due to the finite lifetime of the catalyst. Optimization of pH significantly improved catalytic efficiency with a corresponding savings in treatment costs. Optimal catalytic lifetime of HRP was achieved in the pH range of 7 to 9 for the eight phenolic compounds treated. The minimum residual level to which aromatic substrates were removed from solution was independent of the starting concentration of the aromatic substrate. Enhanced removal of hard-to-remove compounds was noted when mixtures of aromatic substrates were treated. Key words: horseradish peroxidase enzyme, polymerization, wastewater, phenols, aromatics amines.
Reinforced concrete slabs subjected to thermal loads
Authors: Vecchio F. J. , Agostino N. , Angelakos B.
Published: January 2010

Eight large-scale reinforced concrete slab specimens were tested under combined thermal and mechanical load conditions. The specimens varied in the amount and orientation of the in-plane reinforcement provided. A three-phase loading regime was used to investigate thermal gradient effects at service and ultimate load conditions. The slabs experienced significant levels of stressing and cracking as a result of restrained thermal deformations. However, reductions in stiffness due to cracking and thermal creep caused rapid decays in the restraint forces developed. At ultimate load conditions, thermal load effects were minimal. Nonlinear finite element analysis procedures were used to investigate the theoretical response of the test slabs. Fairly accurate simulations of the specimens' behaviour were obtained. Important to achieving accurate results were the consideration of tension stiffening effects and out-of-plane shear behaviour. Key words: analysis, cracking, finite elements, plates, reinforced concrete, slabs, temperature, tests, thermal gradients.
Modélisation du comportement des matières en suspension à l'effluent d'un décanteur primaire lamellaire
Authors: Lessard P. , Martel D. , Desjardins B.
Published: January 2010

Process modelling can prove a useful tool for the control of wastewater treatment plants. The objective of this research was to verify that a primary settling model developped for a conventional process is applicable to a process using lamellar settling. The lumped-parameter model examines the hydraulics of a system composed of stirred tank reactors in series and simulates suspended solid concentration of the effluent under various flow regimes. The model has been validated using data collected from a pilot lamella settler of a capacity of 15 m3 and operated over a wide range of flows (Hazen velocity between 0,43 and 2,59 m∙h−1). The prediction of the model was in agreement with the observed values both in terms of concentration and hydraulic behavior of effluent suspended solids (average relative error of 17%). How ever, less satisfactory was the model performance tested with the concentration data on settleable solids. Research is under way to study the different mechanisms of sedimentation going on in the settler. Key words: modelling, lamellar settling, settleable suspended solids.
Screening of risk management options for abandoned wood-preserving plant sites in Alberta, Canada
Authors: Pollard Simon J.T. , Hoffmann Robert E. , Hrudey Steve E.
Published: January 2010

Several abandoned wood-preserving sites have been identified in Alberta, Canada, which pose a potential threat to human health and the environment. The physiochemical, environmental, and toxicological properties of wood preservatives are discussed together with the predominant human exposure pathways for these chemicals in the environment. A Level II soil fugacity model is used to illustrate the comparative environmental fate of individual organic wood treatment chemicals following release to the soil environment. An evaluation of risk management options at five priority sites is used to illustrate problems associated with the treatment and disposal of mixed organic and inorganic contaminated soils, soil property limitations, and the predominance of organic contaminants within the residual oil phase. The latter reality dominates options for exposure reduction and risk management. Key words: contaminated soils, wood-preserving sites, remediation options, screening, fugacity model.
Change of modal parameters due to crack growth in a tripod tower platform
Authors: Chen Yin , Swamidas A. S. J.
Published: January 2010

Strain gauges, along with an accelerometer and a linear variable displacement transducer, were used in the modal testing to detect a crack in a tripod tower platform structure model. The experimental results showed that the frequency response function of the strain gauge located near the crack had the most sensitivity to cracking. It was observed that the amplitude of the strain frequency response function at resonant points had large changes (around 60% when the crack became a through-thickness crack) when the crack grew in size. By monitoring the change of modal parameters, especially the amplitude of the strain frequency response function near the critical area, it would be very easy to detect the damage that occurs in offshore structures. A numerical computation of the frequency response functions using finite element method was also performed and compared with the experimental results. A good consistency between these two sets of results has been found. All the calculations required for the experimental modal parameters and the finite element analysis were carried out using the computer program SDRC-IDEAS. Key words: modal testing, cracking, strain–displacement–acceleration frequency response functions, frequency–damping–amplitude changes.
A three-year field and laboratory evaluation of linseed oil as a concrete sealer
Authors: Wright J. , Shen Z. , Rizkalla S.
Published: January 2010

Sealers are used to enhance concrete durability through their ability to prevent moisture penetration and chloride intrusion, and, consequently, improve the freeze–thaw performance of the concrete and prevent corrosion of the steel reinforcement, respectively. This paper summarizes the results of three years of comprehensive field and laboratory investigations, undertaken at The University of Manitoba, to study the effectiveness of boiled linseed oil and mineral spirits in comparison to a silane and a siloxane sealer. The field investigation examined the performance of the sealers applied to the concrete pavements of a city street, a provincial highway, and an airport apron in Winnipeg, Manitoba. The laboratory investigation included sealer penetration, salt-water absorption and vapour transmission, abrasion, chloride ion intrusion, surface scaling resistance, and rapid freeze–thaw cycling. Test results of the field and laboratory investigation indicated that boiled linseed oil and mineral spirits was the most effective sealer at reducing chloride ion intrusion. It was found that boiled linseed oil and mineral spirits was comparable to siloxane and much more effective than the silane at reducing salt-water absorption. The results also indicated that boiled linseed oil and mineral spirits was most effective at reducing surface scaling and remained effective when subjected to salt-water absorption after abrasion. Key words: concrete sealers, linseed oil, silane, siloxane, absorption, scaling, chloride intrusion.
Analysis of curved reinforced concrete slab bridges by the spline finite strip method
Authors: Cheung M. S. , Ng S. F. , Zhao J. Q.
Published: January 2010

A layered spline finite strip model for the analysis of reinforced concrete slab bridges is presented in this paper. The natural coordinates ξ–η are adopted to make the method suitable for arbitrary curved slab bridges. A material model based on orthotropic nonlinear elasticity is employed to represent the property of plain concrete. Reinforcement is modeled as an elastoplastic strain-hardening material. The Newton–Raphson method and relaxation techniques are used to solve the nonlinear stiffness equation. Numerical examples are provided to demonstrate the efficiency and accuracy of the model. Key words: spline finite strip method, curved slab bridges, reinforced concrete, nonlinear analysis.
Effect of end distance on the resistance of split ring connectors in timber joints loaded in compression
Authors: Quenneville Pierre , Charron Alain , Van Dalen Karl
Published: January 2010

An experimental program was undertaken to verify the end distance requirements in the Canadian standard for engineering design in wood for split ring connectors in joints loaded in compression. In a laboratory study, 48 joints of the Douglas fir-larch species group using 63 mm diameter split rings, 45 joints of the Douglas fir-larch species group using 102 mm diameter split rings, and 51 joints of the spruce-pine-fir species group using 63 mm diameter split rings were loaded to failure in compression. The split ring end distance varied between 50 and 200 mm for joints with 63 mm diameter split rings and between 80 and 220 mm for joints with 102 mm diameter split rings. Tests were also carried out to verify the cleavage strength of the wood and the strength of the wood in compression parallel-to-grain for each of the specimens. Results show that the end distance does not have any significant effect on the resistance of split ring connectors in joints with members loaded in compression. Key words: split ring, compression, end distance, timber, resistance.
Suspended sediment concentration during river ice breakup
Authors: Prowse T. D.
Published: January 2010

River ice breakup is known to be an important geomorphologic agent, creating numerous erosional and depositional features within river channels and on adjacent floodplains. Despite such evidence, information about the suspended sediment concentration and bed load during breakup is virtually nonexistent. Measurements of suspended sediment concentration were made during the 1987 breakup of the Liard River, N.W.T., Canada. Results showed a gradual rise during the pre-breakup period followed by an order of magnitude increase at the time of the major river-ice run. The ice-affected peak concentration of 1067 mg/L falls within the recorded range of annual open-water peaks that were produced by flow events of 2–5 times greater discharge. Key words: river ice, ice breakup, sediment, flood.
Elastic local buckling of composite tee-beams with longitudinal stiffeners
Authors: Azhari M. , Bradford M. A.
Published: January 2010

The semi-analytical complex finite strip method is used to study the elastic local buckling of composite tee-section beams in negative moment and shear which contain a longitudinal stiffener attached to the web. The optimum position of this stiffener for different positions of the neutral axis is calculated in order to maximize the local buckling stress. Design graphs for longitudinal stiffeners are presented. Interaction curves between shear and bending for different positions of the neutral axis in a stiffened girder are given. Key words: composite beams, elasticity, finite strips, local buckling, longitudinal stiffeners, webs.
Local buckling of Class 2 beam-column flanges
Authors: Dawe J. L. , Lee T. S.
Published: January 2010

Test results are presented and discussed for 18 beam-column specimens subjected to flange local buckling resulting from applied axial and flexural forces. Flanges classified as Class 2 by CAN3-S16.1-M84 “Steel structures for buildings (limit states design)” are investigated. Three different sizes of W shape with different height and web thickness ratios within the Class 2 range were used in this investigation. The flange width-to-thickness ratio was kept constant at the current Class 2 limit [Formula: see text]. Results of this investigation show that the conventional value of plastic moment reduced in the presence of axial load, as based on studies in the late 1950s, does not apply to Class 2 sections. This discrepancy had previously been predicted by an analytical study using an extended Rayleigh–Ritz technique and presented in 1980. Experimental results presented herein verify these predictions. Key words: axial, beam-column, buckling, compact, Class 2, interaction, slenderness.
Spectrum-compatible accelerograms for inelastic seismic analysis of short-period structures located in eastern Canada
Authors: Léger P. , Tayebi A. K. , Paultre P.
Published: January 2010

Smooth design spectra are generally used to describe the seismic excitation provided by the maximum design earthquake for safety evaluation of critical facilities located in eastern Canada. However, a comprehensive study of the inelastic behaviour of critical structural systems requires a step-by-step inelastic analysis in the time domain. This paper presents a study of the inelastic seismic analysis of short-period structures subjected to ground motion acceleration time histories compatible with eastern Canadian conditions and defined (i) from historical records scaled to the smooth design spectrum intensity, (ii) from spectrum-compatible accelerograms generated by random vibration theory, and (iii) from the modification of the Fourier spectrum coefficients of historical records while preserving the original phase angles. The ductility demand, the input energy, the hysteretic energy, the number of yield events, and other performance indices are examined in parametric analyses to identify the type of earthquake motions that is critical for earthquake resistant design of short-period structures. Key words: earthquake resistant design, artificial accelerograms, eastern Canada.
Prestressed concrete masonry walls subjected to uniform out-of-plane loading
Authors: Dawe J. L. , Aridru G. G.
Published: January 2010

Two series of post-tensioned concrete masonry walls subjected to uniform lateral loading were tested to investigate their flexural strength behaviour. Each series of walls consisted of four full-scale prestressed specimens, with varying levels of prestressing force, and one reinforced specimen. Of particular interest were the load–deflection curves, initial cracking loads, wall stiffness, crack patterns, and ultimate failure loads. An air bag test apparatus was used for applying lateral uniform pressures to the specimens. Results of this experimental investigation showed that, for a given wall thickness, increased prestressing force increases the cracking load, initial wall stiffness, and ultimate failure load. The results have established a linear relationship between increased prestressing force and initial cracking load, initial wall stiffness, and ultimate failure load. The proposed model, which takes into account changes in wall stiffness after initial cracking of the wall, accurately predicts wall behaviour. Key words: masonry, prestressed, walls, strength, behaviour, uniform, pressure, experimental, analytical.
Reliability of concrete strength prediction from limited test data
Authors: Jaeger Leslie G. , Bakht Baidar
Published: January 2010

Modifications are provided to a method previously published by the authors to determine lower fractile concrete strength from a limited number of tests. The modifications are aimed at giving estimates of the lower fractile strength that do not exceed the actual strength within a prescribed confidence limit. Another, much simpler, method is also developed to achieve the same goal. Through a large number of tests done through numerical simulations, it is demonstrated that both methods satisfy the required promise of giving safe-side results. However, the simpler method has been found to give better results, despite the simplicity of its application. Key words: compressive strength, concrete, limited test data, lower fractile strength, reliability.
Statistical analyses of damages to buildings in the 1988 Saguenay earthquake
Authors: Paultre Patrick , Lefebvre Guy , Devic Jean-Philippe , Côté Gaétan
Published: January 2010

The 1988 Saguenay earthquake caused a large variety of geotechnical and structural damage. A total of 1927 claim files, most of which were submitted under a compensation program sponsored by the ministère de la Sécurité publique du Québec, Direction générale de la sécurité civile, have been studied. The results of this study are presented in terms of correlations between damage and geographical distribution, earthquake motion characteristics, soil conditions, and type of structures. Site effects are pointed out as one of the main causes of damage to buildings even at large distances from the epicentre. Key words: Saguenay earthquake, distribution of damage, geotechnical damage, structural damage, site effects.
Seasonal temperature and stress distributions in concrete gravity dams. Part 2: behaviour
Authors: Léger P. , Venturelli J. , Bhattacharjee S. S.
Published: January 2010

The thermal response of a typical dam–foundation–reservoir system, using the methodology described in part 1, is presented. Extensive parametric analyses are performed to determine the relative influence, on the thermal and stress–strain responses of the system, due to (i) the geometrical, thermal, and mechanical properties of the dam, (ii) the reservoir, foundation, and air temperature distributions, and (iii) the heat supply from solar radiation. Temperature states to define critical stress conditions for structural safety analyses are determined. Significant thermal stresses occur in the vicinity of the exposed surface of the dam, with a typical depth of frost penetration of about 6 m. The parameters that affect the surface stresses most are the air temperature distribution and the height of the dam, while for frost penetration they are the solar radiation, convection coefficient, and conduction coefficient. Key words: gravity dams, thermal analysis, finite element method.
Grouted anchorages for aramid fibre reinforced plastic prestressing tendons
Authors: McKay K. S. , Erki M. A.
Published: January 2010

Nonmetallic prestressing tendons, made of fibre-reinforced composite materials, are being proposed as alternatives to steel prestressing tendons for bridges and parking garage structures, where corrosion is the leading cause of structural deterioration. One type of commercially available nonmetallic tendons is made of pultruded aramid fibres. One of the main problems for these tendons, which is common to all nonmetallic tendons, is that the high ratio of the axial to lateral strength of fibre-reinforced materials requires special attention to the type of anchorage used. For the aramid tendon, the simplest grouted anchorage consists of a steel tube filled with nonshrink grout, into which the end of the tendon is embedded. This note presents the test results of a parametric study on grouted anchorages for pultruded aramid tendons. Key words: prestressed concrete, nonmetallic tendons, aramid fibre, grouted anchorage.
THE ANGULAR DISTRIBUTION OF GAMMA RAYS IN THE C12(p,p′γ) REACTION
Authors: Gove H. E. , Wall N. S.
Published: January 2010

Protons of 7.1 Mev. energy from the MIT cyclotron have been used to investigate the angular distribution of gamma rays from the C12(p,p′γ) reaction with respect to the incoming proton beam. These gamma rays result from transitions between the first excited state of C12 at 4.45 Mev. and the ground state. The resulting distribution can be fitted by the expansion[Formula: see text]which is consistent with an assignment of two for the angular momentum of the first excited state of C12.
FRONTAL PRECIPITATION AND LIGHTNING OBSERVED BY RADAR
Authors: Marshall J. S.
Published: January 2010

A typical pattern (revealed by radar) of precipitation along a cold front includes both showers containing many nearly vertical cells, and continuous rain characterized by uniformity below the freezing level and the "bright band" of melting snow at that level. Observations in vertical section were made by scanning at angles of elevation up to 30°. At wave length 3 cm., observations of this sort reveal some of the snow above the bright band, and its trailing pattern. At 10.7 cm., little is seen of the snow, but transient echoes with duration of the order of one second are observed, attributable to lightning. These echoes have not been detected when scanning in the vertical at wave length 3.2 cm., although others have reported something of the sort at 3.2 cm. when different observing techniques were used. The transient echoes occur outside, but close to, regions of rain; most frequently about one mile from the top of a shower cell. It is probable, combining 3.2 cm. observations of snow on one occasion with 10.7 cm. observations of the transients on another occasion, that the transients occur in regions not only near rain, but at the same time in or near a region filled with snow.
A DESCRIPTION OF A LARGE DOUBLE-FOCUSING BETA SPECTROMETER AND ITS APPLICATION TO A STUDY OF THE DECAY OF In114
Authors: Johns M. W. , Waterman H. , MacAskill D. , Cox C. D.
Published: January 2010

The design and performance of a Siegbahn type double-focusing beta spectrometer of radius of curvature 50 cm. are described. It has a resolution of 0.3% with a transmission of a few tenths of a per cent. A study of the decay of In114 has revealed gamma rays in the K-capture branch of energies 0.556, 0.576, 0.722, 1.271, and 1.300 Mev. These define excited levels in Cd114 of energies 0.556, 1.278, and 1.856 Mev. above the ground state. The end point of the β spectrum is at 1.984 ± 004 Mev.
MEASUREMENT OF THE HALF-LIVES OF AcC″, Cu66, Mg27, Ti51, Tl206, and V52
Authors: Sargent B. W. , Yaffe L. , Gray A. P.
Published: January 2010

With the exception of AcC″, which was collected by recoil, the radionuclides were produced by irradiating 'spec.-pure' metals or oxides with neutrons in the NRX reactor. The β-activities were measured by the rate of deflection of a quartz liber in an electroscope of recent design. The residual activities were carefully analyzed and eliminated from the main activities by subtraction. Half-lives were determined by the method of least squares. In the case of copper, the effect of the positrons and negatrons from Cu64 was suppressed with an aluminum absorber. The following values were found for the half-lives: AcC″, 4.79 ± 0.02; Cu66, 5.10 ± 0.02; Mg27, 9.45 ± 0.04; Ti51, 5.79 ± 0.03; Tl206, 4.19 ± 0.02; and V52, 3.76 ± 0.02 min. The half-life found for Cu66 from the measurements with the electroscope was confirmed in some measurements with a proportional counter and scale of 1000.
PHOTO-ALPHA PARTICLES FROM SILVER AND BROMINE IRRADIATED WITH 70 MEV. BREMSSTRAHLUNG
Authors: Millar Chas. H.
Published: January 2010

The energy spectrum of the α particles ejected from silver and bromine nuclei has been studied in a nuclear research emulsion irradiated with 70 Mev. brems-strahlung from the Queen's University synchrotron. The main feature of the observed spectrum is a broad group with a peak at about 11 Mev. Evidence for particles of energies less than 6 Mev. is inconclusive.Calculations have been made on the basis of the nuclear evaporation theory and give a predicted spectrum which is consistent in shape and peak position with the observed results.
ENERGY LEVELS IN LEAD AND BISMUTH AND NUCLEAR SHELL STRUCTURE
Authors: Harvey John A.
Published: January 2010

A bismuth target and lead targets enriched in Pb206, Pb207, and Pb208 have been. bombarded with 14-Mev. deuterons from the M.I.T. cyclotron. Proton and triton spectra were measured with aluminum absorbers and a triple proportional counter. The spectra have been carefully analyzed and resolved into a relatively small number of groups. The proton spectra from all four targets are very similar, except for the long range state groups from the Pb206 and Pb207 targets. A striking similarity also occurs among the triton spectra from the four targets. The simplicity in the spectra probably arises because we are dealing with residual nuclei with closed or nearly closed shells of 82 protons and 126 neutrons. The fact that a (d, p) reaction proceeds mainly by means of a stripping process, in which only the neutron enters the nucleus, suggests the possibility that the similarities can be explained by a single particle model of the nucleus. Moreover, the (d, t) reaction is principally a pickup process and thus the single-particle model is suggested again. Observed energy levels are compared with the known levels measured from radiative transitions. Aided by the angular momentum and parity assignments of some of these known levels, tentative assignments of angular momentum and parity are made to many of the new levels from a strong spin-orbit coupling shell model.
Stability analysis of steep rock slopes
Authors: Afrouz A. , Hassani F.P. , Ucar R.
Published: January 2010

A simplified method of predicting the shape and location of the potential failure surface in steep rock slopes is suggested. The 1988 updated Hoek and Brown failure criterion is used with Priest and Brown m and s values and Bieniawski's jointed rock mass classification system. This method is demonstrated by an application to the design of slope reinforcement by rock anchoring and by a case study. The validity of the method is assessed by reference to the variational calculus approach, using the linear Mohr–Coulomb failure criterion. Key words: benches, bench design, bench anchoring, quarrying, slope stability, ground control, rock mass rating.
Thermal and physical properties of candidate buffer–backfill materials for a nuclear fuel waste disposal vault
Authors: Radhakrishna H. S. , Chan H. T. , Crawford A. M. , Lau K. C.
Published: January 2010

As part of the Canadian Nuclear Fuel Waste Management Program, Ontario Hydro has, over several years, conducted research into the behaviour and performance of buffer–backfill for the proposed nuclear fuel waste disposal vault. In this paper, a review has been made of laboratory studies made at Ontario Hydro on the thermal properties, strength, hydraulic conductivity, and compactability of clay-based buffer materials. The results of this work have enabled the formulation of selection criteria for the buffer material mix for the prototype Canadian nuclear fuel waste disposal scheme. Key words: bentonites, buffer, backfill, nuclear waste disposal, thermal conductivity, clays, hydraulic conductivity, compaction, clay barriers, clay seals, shrinkage.
Evaluation of a three-dimensional method of slope stability analysis
Authors: Hungr Oldrich , Salgado F. M. , Byrne P. M.
Published: January 2010

A study comparing a three-dimensional extension of the Bishop simplified method with other limit equilibrium solutions is presented. Very good correspondence is found in cases of rotational and symmetric sliding surfaces, such as ellipsoids. The Bishop method tends to be conservative when applied to nonrotational and asymmetric surfaces because it neglects internal strength. The error is, however, tolerably small for many commonly occurring slide geometries. Indices are proposed to identify cases for which the method should not be used. With its limitations defined, the Bishop simplified method offers a useful algorithm for three-dimensional limit equilibrium analysis. Key words: three-dimensional slope stability analysis.
A-TEAM BASED SUPPLY CHAIN MANAGEMENT AGENT ARCHITECTURE
Authors: ZHENG YUJUN , WANG JINQUAN , XUE JINYUN
Published: January 2010

Today's supply chains increasingly involve complex sets of processes, objectives and constraints, and therefore agent-based architectures for supply chain management (SCM) become much more difficult to implement and maintain. The paper presents a multi-agent architecture for specifying, analyzing and developing SCM systems, in which asynchronous teams (A-Team) of problem solving agents exchange results within populations that provide effective management of information flows in supply chains, and cooperate to produce sets of non-dominated solutions that show the tradeoffs between objectives. Our approach distinguishes itself by improving problem-solving efficiency based on a diverse set of algorithms without complicated synthesis efforts, removing the focus from agent communication and coordination details, and improving reusability, flexibility and extensibility by supporting object-oriented and component-based programming style. We examine the effectiveness of the architecture through a real-world case study and experimental results.
ENHANCED TRAINING FOR THE LOCALLY RECURRENT PROBABILISTIC NEURAL NETWORKS
Authors: GANCHEV TODOR
Published: January 2010

In the present contribution we propose an integral training procedure for the Locally Recurrent Probabilistic Neural Networks (LR PNNs). Specifically, the adjustment of the smoothing factor "sigma" in the pattern layer of the LR PNN and the training of the recurrent layer weights are integrated in an automatic process that iteratively estimates all adjustable parameters of the LR PNN from the available training data. Furthermore, in contrast to the original LR PNN, whose recurrent layer was trained to provide optimum separation among the classes on the training dataset, while striving to keep a balance between the learning rates for all classes, here the training strategy is oriented towards optimizing the overall classification accuracy, straightforwardly. More precisely, the new training strategy directly targets at maximizing the posterior probabilities for the target class and minimizing the posterior probabilities estimated for the non-target classes. The new fitness function requires fewer computations for each evaluation, and therefore the overall computational demands for training the recurrent layer weights are reduced. The performance of the integrated training procedure is illustrated on three different speech processing tasks: emotion recognition, speaker identification and speaker verification.
The Evolutionary Genetics of Emerging Viruses
Authors: Holmes Edward C.
Published: January 2010

RNA viruses are the main agents of emerging disease. To understand how RNA viruses are able to jump species boundaries and spread in new hosts it is essential to determine the basic processes of evolutionary change in these infectious agents. RNA virus evolution is largely shaped by very high rates of mutation. This, coupled with potentially enormous intra- and interhost population sizes and continual replication, allows the rapid production of genetic diversity, including those mutations that facilitate host adaptation. However, high mutation rates also act to constrain aspects of RNA virus evolution, as the majority of mutations, including many at synonymous sites, are deleterious, which in turn places an upper limit on genome size. Ironically, although RNA viruses are characterized by their mutation rates, these rates may not be high enough to allow the onset of quasispecies dynamics, in which natural selection acts on the viral population as a whole.
The Nitrogen Paradox in Tropical Forest Ecosystems
Authors: Hedin Lars O. , Brookshire E.N. Jack , Menge Duncan N.L. , Barron Alexander R.
Published: January 2010

Observations of the tropical nitrogen (N) cycle over the past half century indicate that intact tropical forests tend to accumulate and recycle large quantities of N relative to temperate forests, as evidenced by plant and soil N to phosphorus (P) ratios, by P limitation of plant growth in some tropical forests, by an abundance of N-fixing plants, and by sustained export of bioavailable N at the ecosystem scale. However, this apparent up-regulation of the ecosystem N cycle introduces a biogeochemical paradox when considered from the perspective of physiology and evolution of individual plants: The putative source for tropical N richness—symbiotic N fixation—should, in theory, be physiologically down-regulated as internal pools of bioavailable N build. We review the evidence for tropical N richness and evaluate several hypotheses that may explain its emergence and maintenance. We propose a leaky nitrostat model that is capable of resolving the paradox at scales of both ecosystems and individual N-fixing organisms.
Ifosfamide May Be Safely Used in Patients with End Stage Renal Disease on Hemodialysis
Authors: Latcha Sheron , Maki Robert G. , Schwartz Gary K. , Flombaum Carlos D.
Published: January 2010

Background. Pharmacokinetic data on clearance of ifosfamide in hemodialysis patients are limited. Consequently, these patients are excluded from therapy with this agent. We review the outcomes for patients at our institution with end stage renal disease on dialysis who received ifosfamide for metastatic sarcoma.Patients and Methods. We treated three patients with end stage renal disease on hemodialysis with escalating doses of ifosfamide. Data on radiographic response to therapy, WBC and platelet counts, signs or symptoms of infection, neuropathy and bladder toxicity are reported. Starting doses of ifosfamide were based on review of the literature available with subsequent modifications based on each patient's prior exposure to myelosuppressive agents and on symptoms of neurotoxicity and the degree of myelosuppression following each cycle of chemotherapy.Results. Myelosuppression was the most common side effect from therapy, but no patient developed a life threatening infection, neurotoxicity, or hematuria. One patient developed epistaxis in the setting of thrombocytopenia while on warfarin therapy. All patients had clinical evidence for therapeutic response and two had documented radiographic improvement following ifosfamide administration.Conclusion. Ifosfamide can be used safely in combination with hemodialysis in patients with end stage renal disease.
Reduction of Monocyte Chemoattractant Protein‐1 and Interleukin‐8 Levels by Ticlopidine in TNF‐α Stimulated Human Umbilical Vein Endothelial Cells
Authors: Hu Chaur-Jong , Lee Yueh-Lun , Shih Neng-Yao , Yang Yi-Yuan , Charoenfuprasert Suparat , Dai Yu-Shan , Chang Su-Mei , Tsai Yu-Hui , Tseng How , Liu Chia-Yu , Leu Sy-Jye
Published: January 2010

Atherosclerosis and its associated complications represent major causes of morbidity and mortality in the industrialized or Western countries. Monocyte chemoattractant protein‐1 (MCP‐1) is critical for the initiating and developing of atherosclerotic lesions. Interleukin‐8 (IL‐8), a CXC chemokine, stimulates neutrophil chemotaxis. Ticlopidine is one of the antiplatelet drugs used to prevent thrombus formation relevant to the pathophysiology of atherothrombosis. In this study, we found that ticlopidine dose‐dependently decreased the mRNA and protein levels of TNF‐α‐stimulated MCP‐1, IL‐8, and vascular cell adhesion molecule‐1 (VCAM‐1) in human umbilical vein endothelial cells (HUVECs). Ticlopidine declined U937 cells adhesion and chemotaxis as compared to TNF‐α stimulated alone. Furthermore, the inhibitory effects were neither due to decreased HUVEC viability, nor through NF‐kB inhibition. These results suggest that ticlopidine decreased TNF‐α induced MCP‐1, IL‐8, and VCAM‐1 levels in HUVECs, and monocyte adhesion. Therefore, the data provide additional therapeutic machinery of ticlopidine in treatment and prevention of atherosclerosis.
Approximation of Common Fixed Points of a Countable Family of Relatively Nonexpansive Mappings
Authors: Boonchari Daruni , Saejung Satit
Published: January 2010

We introduce two general iterative schemes for finding a common fixed point of a countable family of relatively nonexpansive mappings in a Banach space. Under suitable setting, we not only obtain several convergence theorems announced by many authors but also prove them under weaker assumptions. Applications to the problem of finding a common element of the fixed point set of a relatively nonexpansive mapping and the solution set of an equilibrium problem are also discussed.
Fixed Points for Discontinuous Monotone Operators
Authors: Cui Yujun , Zhang Xingqiu
Published: January 2010

We obtain some new existence theorems of the maximal and minimal fixed points for discontinuous monotone operator on an order interval in an ordered normed space. Moreover, the maximal and minimal fixed points can be achieved by monotone iterative method under some conditions. As an example of the application of our results, we show the existence of extremal solutions to a class of discontinuous initial value problems.
Altered Expression of Neurotensin Receptors Is Associated with the Differentiation State of Prostate Cancer
Authors: Swift Stephanie L. , Burns Julie E. , Maitland Norman J.
Published: January 2010

In prostate cancer, traditional treatments such as androgen response manipulation often provide only temporary resolution of disease, with emergence of a more aggressive, androgen-independent tumor following initial therapy. To treat recurrent disease, cell surface proteins that are specifically overexpressed on malignant cells may be useful for generating targeted therapeutics. Recent evidence suggests that neurotensin receptors (NTR) are recruited in advanced prostate cancer as an alternative growth pathway in the absence of androgens. In this study, we assessed the potential use of these receptors as targets by analyzing NTR expression patterns in human prostate cell lines and primary prostate tumor cell cultures derived from patient samples. In primary tumor cell cultures, NTR1 was upregulated in cells with a basal phenotype (cytokeratin 1/5/10/14+), whereas NTR2 and NTR3 were upregulated in cells with luminal phenotype (cytokeratin 18+). Similar patterns of NTR expression occurred in benign prostate tissue sections, implicating differentiation state as a basis for the differences observed in tumor cell lines. Our findings support the use of NTRs as tools for therapeutic targeting in prostate cancers composed of both poorly differentiated and/or well-differentiated cells. Cancer Res; 70(1); 347–56
α2-Macroglobulin Inhibits the Malignant Properties of Astrocytoma Cells by Impeding β-Catenin Signaling
Authors: Lindner Inge , Hemdan Nasr Y.A. , Buchold Martin , Huse Klaus , Bigl Marina , Oerlecke Ilka , Ricken Albert , Gaunitz Frank , Sack Ulrich , Naumann Andreas , Hollborn Margrit , Thal Dietmar , Gebhardt Rolf , Birkenmeier Gerd
Published: January 2010

Targets that could improve the treatment of brain tumors remain important to define. This study of a transformation-associated isoform of α2-macroglobulin (A2M*) and its interaction with the low-density lipoprotein receptor-related protein-1 (LRP1) suggests a new mechanism for abrogating the malignant potential of astrocytoma cells. LRP1 bound A2M* found to be associated with an inhibition of tumor cell proliferation, migration, invasion, spheroid formation, and anchorage-independent growth. Transcriptional studies implicated effects on the Wnt/β-catenin signaling pathway. Notably, LRP1 antibodies could phenocopy the effects of A2M*. Our findings suggest a pathway of tumor suppression in astrocytoma that might be tractable to therapeutic exploitation. Cancer Res; 70(1); 277–87
Characterization of Melanoma Cells Capable of Propagating Tumors from a Single Cell
Authors: Held Matthew A. , Curley David P. , Dankort David , McMahon Martin , Muthusamy Viswanathan , Bosenberg Marcus W.
Published: January 2010

Questions persist about the nature and number of cells with tumor-propagating capability in different types of cancer, including melanoma. In part, this is because identification and characterization of purified tumorigenic subsets of cancer cells has not been achieved to date. Here, we report tumor formation after injection of single purified melanoma cells derived from three novel mouse models. Tumor formation occurred after every injection of individual CD34+p75− melanoma cells, with intermediate rates using CD34−p75− cells, and rarely with CD34−p75+ cells. These findings suggest that tumorigenic melanoma cells may be more common than previously thought and establish that multiple distinct populations of melanoma-propagating cells (MPC) can exist within a single tumor. Interestingly, individual CD34−p75− MPCs could regenerate cellular heterogeneity after tumor formation in mice or multiple passages in vitro, whereas CD34+p75− MPCs underwent self-renewal only, showing that reestablishment of tumor heterogeneity is not always a characteristic of individual cells capable of forming tumors. Functionally, single purified MPCs were more resistant to chemotherapy than non-MPCs. We anticipate that purification of these MPCs may allow a more comprehensive evaluation of the molecular features that define tumor-forming capability and chemotherapeutic resistance in melanoma. Cancer Res; 70(1); 388–97
Diagnostic and Therapeutic Potential of a Human Antibody Cloned from a Cancer Patient That Binds to a Tumor-Specific Variant of Transcription Factor TAF15
Authors: Schatz Nicole , Brändlein Stephanie , Rückl Kilian , Hensel Frank , Vollmers H. Peter
Published: January 2010

Human hybridoma technologies permit the cloning of patient antibodies that may have desirable qualities. In this study, we report the isolation of a natural IgG antibody from a stomach cancer patient that illustrates novel diagnostic and therapeutic uses. Human antibody PAT-BA4 recognizes a tumor-specific variant of the transcription factor TATA-binding protein–associated factor 15 (TAF15) that is expressed on the plasma membrane of stomach cancer and melanoma cells but not healthy tissues. TAF15 is a member of the multifunctional TET protein family involved in mRNA transcription, splicing, and transport that is normally expressed only in the cytoplasm and nucleus of fetal or adult tissue cells. However, in malignant cells, TET family members including TAF15 seem to be involved in cell adhesion and spreading. In support of this likelihood, we found that PAT-BA4 inhibited tumor cell motility and tumor cell adhesion. Our findings define a role for a tumor-specific TAF15 antigen in malignant processes. Cancer Res; 70(1); 398–408
Insulin-Like Growth Factor-I Regulates the Liver Microenvironment in Obese Mice and Promotes Liver Metastasis
Authors: Wu Yingjie , Brodt Pnina , Sun Hui , Mejia Wilson , Novosyadlyy Ruslan , Nunez Nomeli , Chen Xiaoli , Mendoza Arnulfo , Hong Sung-Hyeok , Khanna Chand , Yakar Shoshana
Published: January 2010

Among the mechanisms implicated in the tumor-promoting effects of obesity, signaling by insulin-like growth factor-I (IGF-I) and insulin has received considerable attention. However, the emerging realization that obesity is associated with chronic inflammation has prompted other consideration of how the IGF-I axis may participate in cancer progression. In the present study, we used two mouse models of chronic (LID) and inducible (iLID) igf-1 gene deficiency in the liver to investigate the role of IGF-I in regulating the host microenvironment and colorectal carcinoma growth and metastasis in obese mice. Obese mice had a heightened inflammatory response in the liver, which was abolished in mice with chronic IGF-I deficiency (LID). In control animals changes to the hepatic microenvironment associated with obesity sustained the presence of tumor cells in the liver and increased the incidence of hepatic metastases after intrasplenic/portal inoculation of colon carcinoma cells. These changes did not occur in LID mice with chlonic IGF-1 deficiency. In contrast, these changes occured in iLID mice with acute IGF-1 deficiency, in the same manner as the control animals, revealing a fundamental difference in the nature of the requirement for IGF-1 on tumor growth and metastasis. In the setting of obesity, our findings imply that IGF-1 is critical to activate and sustain an inflammatory response in the liver that is needed for hepatic metastasis, not only through direct, paracrine effect on tumor cell growth, but also through indirect effects involving the tumor microenvironment. Cancer Res; 70(1); 57–67