bluuebunny/crossref_metadata_2025 huggingface dataset:
Revisiting arching in deck slabs
Authors: Bakht Baidar
Published: January 2010

The arching action in concrete deck slabs of girder bridges is generally recognized and is utilized by the Ontario Highway Bridge Design Code, and some other codes, to specify an empirical design method which leads to considerable savings in the amount of reinforcement. Despite this general recognition, there are some aspects of the arching action that are yet to be explored. To the knowledge of the author, all reported laboratory and field tests on deck slabs exploring its arching action under applied loads have been conducted by measuring strains in the bottom transverse reinforcement midway between the girders. Based on the results of tests on a full-scale model of a deck slab, it has been confirmed in this note that the transverse bottom reinforcement in the deck slab acts as a tie to the internal transverse arch in the slab. Because of embedment in concrete, the force in this reinforcement is the smallest midway between the girders, and not the largest as would be the case if the slab were in pure bending. Key words: arching in slabs, deck slabs, girder bridge, punching shear, steel-free deck slabs.
On the use of springs in stress-laminated wood decks
Authors: Bakht Baidar , Jaeger Leslie G.
Published: January 2010

Transverse post-tensioning forces, essential for the structural integrity of stress-laminated wood decks, are subject to losses because of the time- and stress-dependent shrinkage of wood. Through physical testing conducted over the last 20 years, it has been found by a number of researchers that the prestress losses in these structures can be minimized by reducing the stiffness of the post-tensioning system and also by incorporating mechanical springs between the deck and the post-tensioning system. From this observation, it has been generally concluded by the investigators that the incorporation of springs in stress-laminated wood decks is equivalent to reducing the stiffness of the post-tensioning system. In this note, it is argued that this assumed equivalence is not true, but that the springs are nevertheless effective in reducing prestress losses in stress-laminated wood decks. Key words: post-tensioning, prestress losses, stress-laminated wood deck, wood bridge, wood deck.
Critical review of the CSA A23.3-94 punching shear strength provisions for interior columns
Authors: Sherif Alaa G. , Dilger Walter H.
Published: January 2010

The purpose of this paper is to demonstrate that the shear design of slabs according to the relevant Canadian CSA A23.3-94 (and U.S. ACI 318-95) design codes can be unsafe under certain conditions, and to propose improved design equations, some of which should be considered immediately for implementation in the Canadian CSA code. The paper deals with interior slab–column connections, with and without shear reinforcement, subjected to shear force alone or to a combination of shear force and unbalanced bending moment. Some comparisons with the British code BS 8110-85 and the CEB –FIP model code 1990 are also made. Tests reported in the literature and some experiments by the authors provide the basis for this study. Key words: flat concrete plates, slab–column connections, shear strength, punching shear, shear reinforcement, moment transfer.
Évaluation de la filtration sur tourbe et compost pour le traitement de l'effluent d'une usine de compostage de résidus verts
Authors: Lafrance Claire , Lessard Paul , Buelna Gerardo
Published: January 2010

Yard waste compost leachates may contain relatively high concentrations of organic matter and thus require treatment before being released into the environment. The leachate used in this study is characterized by variations in organic content, BOD5 (biochemical oxygen demand after a 5-day incubation period at 20 °C) varying from 100 to 5000 mg/L. Promising results were obtained in the laboratory using 20-L biofilters of peat and compost as filtering media for the treatment of this effluent. BOD5 reductions of 82% at an organic loading of 0.21 kg BOD5/m3∙d, and of more than 80% for SS (suspended solids) were obtained. Residual color in the effluent of the columns, leached from the humic material used as filtering medium, affected COD reduction, which reached 70% at best. Compost biofilters were as efficient as peat biofilters for reduction of SS and BOD5, and could be regarded as economical filtering media for treating leachate from composting sites. However, the effluents treated by these units did not meet Quebec standards for release into some surface water systems or storm sewers when the higher organic loads were used (0,21 and 0,42 kg BOD5/m3∙d). Key words: composting, yard waste, compost leachate, biofiltration, peat.
Combined wave – iceberg loading on offshore structures
Authors: Foschi Ricardo , Isaacson Michael , Allyn Norman , Yee Steven
Published: January 2010

The Canadian Standards Association has developed and published a code for the design and construction of fixed offshore structures. This code has been subjected to a comprehensive verification process which has identified several issues warranting further study. One of these relates to the combined effects of wave and iceberg collision loading. At present, this combination is treated by the use of a load combination factor specified in the Code. The present paper describes a recent study which was undertaken to determine the appropriateness of the recommended value of the load combination factor. The study involves a numerical analysis in which loads due to waves alone, an iceberg alone, and an iceberg and waves in combination have been calculated for a range of iceberg and wave parameters. These results have been applied to a first-order reliability analysis in order to study the force levels corresponding to an annual probability of 10−4 or to the onset of global sliding with an annual probability of 10−4. The paper thereby makes recommendations for load combination factors applicable to combined wave–iceberg loading. Key words: hydrodynamics, icebergs, ocean engineering, offshore structures, wave forces, waves.
Nonlinear analysis of cable-stayed bridges at ultimate load level
Authors: Khalil M. S.
Published: January 2010

Cable-stayed bridges have unique characteristics which require unique treatment in their analysis, design, and construction. This paper discusses some of these characteristics and presents proposed means of solving the associated problems. The paper discusses the nonlinear behaviour of the cable-stayed system, the load factors required for the analysis of that type of bridge, the manner of application of the loads, and the analysis under factored loads. The paper presents the results of the analysis of the ALRT cable-stayed bridge in Vancouver, Canada. Key words: cable-stayed, bridges, nonlinear, load factor, safety index.
Frequency analysis of low flows using the Akaike information criterion
Authors: Lawal Semiu A. , Watt W. Edgar
Published: January 2010

It is the current practice in frequency analysis of low flows to consider only three-parameter distributions in which one of the parameters represents a nonzero lower bound. When applied to the small samples typically available, this practice results in incorrect low flow estimates. These errors are related to errors in the estimated lower bound. To preclude this possibility, it is proposed that the current practice be changed to include the selection of a two-parameter distribution in certain situations. To assess this proposal, the Akaike information criterion (AIC) is used to compare the suitability of the most commonly used three-parameter distribution (three-parameter Weibull) and three two-parameter distributions (two-parameter Weibull, Gumbel, and lognormal) to low flow data for 51 long-term hydrometric stations across Canada. For 75% of the stations, a two-parameter distribution is selected over the three-parameter distribution if the selection criterion is minimum AIC. In about one third of the remaining 25% of the stations where the three-parameter Weibull distribution gave the minimum AIC, the estimated lower bound is sufficiently close to the minimum observed low flow to indicate overfitting and hence unreliable quantile estimates. When the AIC is supplemented with visual examination of goodness of fit on probability plots, it is found that the lognormal distribution could very well fit those cases where the AIC selected the three-parameter Weibull distribution. Key words: low flow frequency, goodness of fit, information criterion, probability plot.
Calcul de la rigidité de torsion des poutres en béton armé fissurées en flexion
Authors: Hannachi Naceur Eddine , Fouré Bernard
Published: January 2010

This paper proposes a method to calculate the torsional stiffness of reinforced concrete beams with section of any shape, in a cracked state due to bending, subjected to small torque (shape stability problems). The simultaneous influence of the various parameters (shape of the section, state of cracking, longitudinal reinforcement) is taken into account. A series of laboratory tests on beams with hollow, massive, or double-tee thin cross sections gives data to determine semi-empirically some parameters. Calculated and experimental stiffnesses are in rather good agreement. The proposed method fills in a gap in the nonlinear calculation of reinforced concrete. Key words: reinforced concrete, flexural cracking, torsional stiffness, calculation method, nonlinear elasticity, stability.
Comportement thermique et mécanique du béton de masse au jeune âge
Authors: Bouzoubaâ N. , Lachemi M. , Aïtcin P.-C. , Miao B.
Published: January 2010

The paper presents the main results obtained from experimental and numerical investigations of the thermal and mechanical behaviors observed during curing of a massive concrete element made with type 20M cement. An experimental concrete block 920 mm in diameter and 1000 mm in thickness was instrumented with thermocouples and vibrating-wire strain gages in order to monitor the early age behavior of mass concrete. A numerical model was used to predict the temperature field that occurs in the concrete element upon hydration of cement. The modeling of the mechanical behavior was achieved using a law that accounts for autogenous shrinkage. The experimental results illustrate the importance of selecting the type of cement for use in mass concrete. The data provided by the numerical models are in good agreement with the experimental results. Key words: dam, mass concrete, deformation, finite elements, thermal gradient, instrumentation, autogenous shrinkage, temperature. [Journal translation]
A grey hop, skip, and jump approach: generating alternatives for expansion planning of waste management facilities
Authors: Huang G. H. , Baetz B. W. , Patry G. G.
Published: January 2010

A grey hop, skip, and jump (GHSJ) approach is developed and applied to the area of municipal solid waste management planning. The method improves upon existing modelling to generate alternative approaches by allowing uncertain information to be effectively communicated into the optimization process and resulting solutions. Feasible decision alternatives can be generated through interpretation of the GHSJ solutions, which are capable of reflecting potential system condition variations caused by the existence of input uncertainties. Results from a hypothetical case study indicate that useful solutions for the expansion planning of waste management facilities can be generated. The decision alternatives obtained from the GHSJ solutions may be interpreted and analyzed to internalize environmental–economic tradeoffs, which may be of interest to solid waste decision makers faced with difficult and controversial choices. Key words: grey programming, modelling to generate alternatives, hop-skip-jump approach, waste management planning, uncertainty, public sector decision making.
Seismic analysis and design of the skytrain cable-stayed bridge
Authors: Khalil M. S.
Published: January 2010

The Skytrain Fraser River Crossing near Vancouver is a cable-stayed bridge completed in late 1988. The bridge is located in a highly seismic area with different soil conditions on the two banks of the river and liquefaction potential in the event of a major earthquake. This paper discusses the analysis and design considerations of the bridge for earthquake effects. Discussed in the paper are site conditions, design criteria, input motion, analysis methods, and design parameters. Key words: cable-stayed, bridges, seismic, response spectra, detailing.
Slenderness ratio of main members between interconnectors of built-up compression members
Authors: Temple Murray C. , Elmahdy Ghada M.
Published: January 2010

Many steel design standards, including CAN/CSA-S16.1-M89 "Limit states design of steel structures," specify maximum slenderness ratios for the individual main members between the interconnectors of built-up compression members. Previous research on which these requirements are based is reviewed. It is shown that the imperfection sensitivity due to coupled instabilities is measured from bifurcation critical loads. However, steel standards are based on a compressive resistance determined for a member with an initial out-of-straightness and a suitable residual stress pattern. It is shown that the use of an equivalent slenderness ratio equation is sufficient to predict the compressive resistance of these built-up members. Further restrictions on the slenderness ratio of built-up members between interconnectors are not warranted. Thus, the elimination of these requirements from S16.1-94 is justified. Key words: built-up members, codes, compressive resistance, coupled instabilities, equivalent slenderness ratio, interconnectors.
First principles studies of silicon as a negative electrode material for lithium-ion batteries
Authors: Chevrier V. L. , Zwanziger J. W. , Dahn J. R.
Published: January 2010

An investigation of Li–Si alloys using density functional theory is presented. Various calculation methods and pseudopotentials are analyzed to best reproduce the potential versus composition curve of a Li/LixSi electrochemical cell at high temperature using the experimentally observed Li–Si phases. Total energy calculations, structural optimizations, and bulk modulus estimations were completed for the Si, Li12Si7, Li7Si3, Li13Si4, Li15Si4, Li22Si5, and Li phases. The potential plateaus of the co-existing phase regions, obtained using the projector augmented wave (PAW) method, have an average absolute error of 31 mV with respect to experiment. The Li7Si3 and Li15Si4 compositions are discussed and the Li15Si4 phase is found to have a lower bulk modulus relative to the other phases.
Solutions of nonlinear Schrödinger equation for interfacial waves propagating between two ideal fluids
Authors: Abourabia A. M. , Mahmoud M. A. , Khedr G. M.
Published: January 2010

We present solutions to the problem of waves propagating at an interface between two inviscid fluids of infinite extent and differing densities. The method of multiple scale is employed to obtain a dispersion relation and nonlinear Schrödinger (NLS) equation, which describes the behavior of the system for the fluid interface. The dispersion relation of the model NLS equation is studied. The solutions of the NLS equation are derived analytically by using the complex tanh-function method and the function transformation method into a sine-Gordon equation. Also, diagrams are drawn to illustrate the elevation of the interface, the slip velocity, and the conservation of power. We observe that the elevation of the interface is in the form of traveling quasi-solitary waves that decrease as the wave number increases. We see that the slip velocities also bring a nonlinear and periodic characters. Finally, we observe that the conservation of power is in the form of traveling waves. Also, as the wave number increases, the conservation of power is more accurate in fluctuating around zero.
On wave functional in QED
Authors: Liu Daqing
Published: January 2010

In a discrete form of the second quantization, the gauge independencies of all the physical states including a vacuum in quantum electrodynamics are restudied through a new approach. We also discuss an interesting phenomenon attributed to the vacuum effect and come up with a procedure to produce general physical states.
GRB 011211: An alternative interpretation of the optical and X-ray spectra in terms of blueshifts
Authors: Basu D.
Published: January 2010

The redshift of the gamma-ray burst (GRB) GRB 011211 has been determined as 2.14 from several absorption lines seen in the spectrum of its optical afterglow. The spectrum of its X-ray afterglow exhibited several emission lines, and their identification led to a mean redshift 1.862. A supernova model has been proposed based on the redshift of the GRB as 2.141. It is shown here that the redshift interpretation cannot explain the observed spectra, as some serious inconsistencies exist in the process of redshift determinations in spectra of both optical and X-ray afterglows. In view of that, an alternative interpretation of the spectra is presented in terms of blueshifts. An ejection mechanism is proposed as a possible scenario to explain the blueshifted spectrum.
Motion of a circular cylinder on a smooth surface
Authors: Shegelski Mark R.A. , Kellett Ian , Friesen Hal , Lind Crystal
Published: January 2010

We present a pedagogical treatment of a circular cylinder moving over a smooth surface with one point of the cylinder making contact with the surface. We derive the equations of motion using Newton’s laws. The simplicity of this approach makes the results easily within reach of undergraduate students. A careful derivation of the equations is presented first, and then we show how easily one could make an error. We illustrate how instructors could use this calculation to teach students how to detect errors and critically examine assumptions, including those that seem beyond question. Circular motion with no slipping is examined and we demonstrate the extent of possible motions for static friction. Some calculations are listed that instructors can assign to students to teach the points made in this paper.
A NOTE ON CAPILLARY INVASION IN NON-UNIFORM CHANNELS
Authors: HYVÄLUOMA JARI
Published: January 2010

We investigate imbibition of a wetting liquid in power-law-shaped channels by numerical simulations with a two-phase lattice Boltzmann model. At short times, the dynamics of the imbibition follows diffusive scaling similar to that in uniform capillaries, but at longer times power-law behavior with exponent depending on the channel shape changes is observed. The observed behavior is in exact agreement with a recent theory of Reyssat and co-workers.1
COMPUTATIONAL STUDY OF THE TRANSMISSION OF ENERGY IN A TWO-DIMENSIONAL LATTICE WITH NEAREST-NEIGHBOR INTERACTIONS
Authors: MACÍAS-DÍAZ J. E. , RUIZ-RAMÍREZ J. , FLORES-OROPEZA L. A.
Published: January 2010

In this work, we establish computationally the existence of the process of nonlinear supratransmission in the simplest generalization of the classical β-Fermi–Pasta–Ulam chain to two-space dimensions, subject to harmonic boundary data in one end of the Dirichlet form. Our simulations employ a finite-difference scheme with multiple properties of consistency in the domains of the solutions, the local energy density and the total energy of the system. Moreover, our results establish the presence of the phenomenon of nonlinear infratransmission or lower-transmission, thus proving the existence of a bistable region where a conducting and an insulating regimes coexist.
A CAPACITIVE IMAGE ANALYSIS SYSTEM TO CHARACTERIZE THE SKIN SURFACE
Authors: GHERARDI ALESSANDRO , BEVILACQUA ALESSANDRO
Published: January 2010

The assessment of the skin surface is of a great importance in the dermocosmetic field to evaluate the response of individuals to medical or cosmetic treatments. In vivo quantitative measurements of changes in skin topographic structures provide a valuable tool, thanks to noninvasive devices. However, the high cost of the systems commonly employed is limiting, in practice, the widespread use of these devices for a routine-based approach. In this work we resume the research activity carried out to develop a compact low-cost system for skin surface assessment based on capacitive image analysis. The accuracy of the capacitive measurements has been assessed by implementing an image fusion algorithm to enable a comparison between capacitive images and the ones obtained using high-cost profilometry, the most accurate method in the field. In particular, very encouraging results have been achieved in the measurement of the wrinkles' width. On the other hand, experiments show all the native design limitations of the capacitive device, primarily conceived to work with fingerprints, to measure the wrinkles' depth, which point toward a specific re-designing of the capacitive device.
Arabic Natural Language Processing
Authors: Farghaly Ali , Shaalan Khaled
Published: January 2010

The Arabic language presents researchers and developers of natural language processing (NLP) applications for Arabic text and speech with serious challenges. The purpose of this article is to describe some of these challenges and to present some solutions that would guide current and future practitioners in the field of Arabic natural language processing (ANLP). We begin with general features of the Arabic language in Sections 1, 2, and 3 and then we move to more specific properties of the language in the rest of the article. In Section 1 of this article we highlight the significance of the Arabic language today and describe its general properties. Section 2 presents the feature of Arabic Diglossia showing how the sociolinguistic aspects of the Arabic language differ from other languages. The stability of Arabic Diglossia and its implications for ANLP applications are discussed and ways to deal with this problematic property are proposed. Section 3 deals with the properties of the Arabic script and the explosion of ambiguity that results from the absence of short vowel representations and overt case markers in contemporary Arabic texts. We present in Section 4 specific features of the Arabic language such as the nonconcatenative property of Arabic morphology, Arabic as an agglutinative language, Arabic as a pro-drop language, and the challenge these properties pose to ANLP. We also present solutions that have already been adopted by some pioneering researchers in the field. In Section 5 we point out to the lack of formal and explicit grammars of Modern Standard Arabic which impedes the progress of more advanced ANLP systems. In Section 6 we draw our conclusion.
Cross-Language Information Propagation for Arabic Mention Detection
Authors: Zitouni Imed , Florian Radu
Published: January 2010

In the last two decades, significant effort has been put into annotating linguistic resources in several languages. Despite this valiant effort, there are still many languages left that have only small amounts of such resources. The goal of this article is to present and investigate a method of propagating information (specifically mention detection) from a resource-rich language into a relatively resource-poor language such as Arabic. Part of the investigation is to quantify the contribution of propagating information in different conditions based on the availability of resources in the target language. Experiments on the language pair Arabic-English show that one can achieve relatively decent performance by propagating information from a language with richer resources such as English into Arabic alone (no resources or models in the source language Arabic). Furthermore, results show that propagated features from English do help improve the Arabic system performance even when used in conjunction with all feature types built from the source language. Experiments also show that using propagated features in conjunction with lexically derived features only (as can be obtained directly from a mention annotated corpus) brings the system performance at the one obtained in the target language by using feature derived from many linguistic resources, therefore improving the system when such resources are not available. In addition to Arabic-English language pair, we investigate the effectiveness of our approach on other language pairs such as Chinese-English and Spanish-English.
Automatic Speech-to-Text Transcription in Arabic
Authors: Lamel Lori , Messaoudi Abdelkhalek , Gauvain Jean-Luc
Published: January 2010

The Arabic language presents a number of challenges for speech recognition, arising in part from the significant differences in the spoken and written forms, in particular the conventional form of texts being non-vowelized. Being a highly inflected language, the Arabic language has a very large lexical variety and typically with several possible (generally semantically linked) vowelizations for each written form. This article summarizes research carried out over the last few years on speech-to-text transcription of broadcast data in Arabic. The initial research was oriented toward processing of broadcast news data in Modern Standard Arabic, and has since been extended to address a larger variety of broadcast data, which as a consequence results in the need to also be able to handle dialectal speech. While standard techniques in speech recognition have been shown to apply well to the Arabic language, taking into account language specificities help to significantly improve system performance.
FEATUREWhy marketing research makes us cringe
Authors: Formosa Dan
Published: January 2010

(Does it bother anyone that design continues to be driven by awful marketing techniques?)
Measuring and guaranteeing quality of barrier coverage for general belts with wireless sensors
Authors: Chen Ai , Lai Ten H. , Xuan Dong
Published: January 2010

Sensors may fail due to various reasons such as heat, malicious activity, environmental hazards, extended use, and lack of power. As more and more sensors fail, certain desired properties such as barrier coverage will diminish and eventually fall below a desired level. In such a case, the network will have to be repaired. It is therefore desirable to have mechanisms to monitor network properties. In this article, we are interested in measuring the quality of barrier coverage, which is known to be an appropriate model of coverage for movement detection applications such as intrusion detection.

In the literature, researchers only consider whether or not a sensor network provides barrier coverage. This is equivalent to measuring its quality as either 0 or 1. We believe quality of barrier coverage is not binary and propose a metric for measuring it. If the measured quality is short of a desired value, we further identify all local regions that need to be repaired. The identified regions are minimal in the sense that if one of them is not repaired then the resulting network will still be short of quality. We also discuss how to actually repair a region.
Key predistribution using combinatorial designs for grid-group deployment scheme in wireless sensor networks
Authors: Ruj Sushmita , Roy Bimal
Published: January 2010

We propose a new grid-group deployment scheme in wireless sensor networks. We use combinatorial designs for key predistribution in sensor nodes. The deployment region is divided into square regions. The predistribution scheme has the advantage that all nodes within a particular region can communicate with each other directly and nodes which lie in a different regions can communicate via special nodes called agents which have more resources than the general nodes. The number of agents in a region is always three, whatever the size of the network. We give measures of resiliency taking the Lee distance into account. Apart from considering the resiliency in terms of fraction of links broken, we also consider the resiliency as the number of nodes and regions disconnected when some sensor are compromised. This second measure, though very important, had not been studied so far in key predistribution schemes which use deployment knowledge. We find that the resiliency as the fraction of links compromised is better than existing schemes. The number of keys preloaded in each sensor node is much less than all existing schemes and nodes are either directly connected or connected via two hop paths. The deterministic key predistribution schemes result in constant-time computation overhead for shared key discovery and path key establishment.
Elliptical anomalies in wireless sensor networks
Authors: Rajasegarar Sutharshan , Bezdek James C. , Leckie Christopher , Palaniswami Marimuthu
Published: January 2010

Anomalies in wireless sensor networks can occur due to malicious attacks, faulty sensors, changes in the observed external phenomena, or errors in communication. Defining and detecting these interesting events in energy-constrained situations is an important task in managing these types of networks. A key challenge is how to detect anomalies with few false alarms while preserving the limited energy in the network. In this article, we define different types of anomalies that occur in wireless sensor networks and provide formal models for them. We illustrate the model using statistical parameters on a dataset gathered from a real wireless sensor network deployment at the Intel Berkeley Research Laboratory. Our experiments with a novel distributed anomaly detection algorithm show that it can detect elliptical anomalies with exactly the same accuracy as that of a centralized scheme, while achieving a significant reduction in energy consumption in the network. Finally, we demonstrate that our model compares favorably to four other well-known schemes on four datasets.
Distributed algorithm for node localization in wireless ad-hoc networks
Authors: Cheng Bing Hwa , Vandenberghe Lieven , Yao Kung
Published: January 2010

We present a distributed algorithm for node localization based on the Gauss-Newton method. In this algorithm, each node updates its own location estimate using the pairwise distance measurements and the local information it receives from the neighboring nodes. Once the location estimate is updated, the sensor node broadcasts the updated estimate to all the neighboring nodes. A distributed and scalable local scheduling algorithm for updating nodes in the network is presented to avoid the use of the global coordinator or a routing loop. We analytically show that the proposed distributed algorithm converges under certain practical assumptions of the network. The performance of the algorithm is evaluated using both simulation and experimental results. Quantitative comparisons among different distributed algorithms are also presented.
Why Discipline Matters in Computing Education Scholarship
Authors: Tenenberg Josh , McCartney Robert
Published: January 2010

Scholarly communities in computing determine how to produce and validate knowledge within their domains of focus. Much of this knowledge can remain tacit because of shared ways of becoming a disciplinary scholar within any particular area of computing. But such tacitness presents challenges for computing education scholarship, since knowledge about how to create and validate claims about human thinking and learning is rarely a part of the training for computing educators. The editors-in-chief of TOCE have responded to these challenges by making explicit the epistemic practices associated with the publication of its manuscripts, by encouraging a range of borrowing from other disciplines, and by instituting feedback loops at all levels of review.
Lattice methods for fluid animation in games
Authors: Judice Sicilia F. , Coutinho Bruno Barcellos S. , Giraldi Gilson A.
Published: January 2010

In this work, we focus on fluid modeling and animation via lattice methods for computer games. We consider two approaches in this area: a Lattice Gas Cellular Automata (LGCA) technique and the Lattice Boltzmann (LBM) Method. LGCAs are discrete models based on point particles that move on a lattice according to suitable and simple rules in order to mimic a fully molecular dynamics. The LBM method is based on the fundamental idea of constructing simplified kinetic models, which incorporates the essential physics of microscopic processes so that the macroscopic averaged properties satisfy macroscopic equations. In this article, we present two animating frameworks based on the above-mentioned lattice methods. Both frameworks are composed of two models: (a) a 3D fluid animation technique; and (b) a GPU surface flow animation over terrain models. In the first framework, item (a) is performed through a LGCA, while in the second one we applied the LBM. In this work we highlight the advantages of these approaches for computer game applications. In the experimental results, we emphasize the simplicity and power of the presented models when combined with efficient techniques for rendering, and compare them in terms of efficiency.
Comparison of the Keratometric Corneal Astigmatic Power after Phacoemulsification: Clear Temporal Corneal Incision versus Superior Scleral Tunnel Incision
Authors: He Yongqi , Zhu Siquan , Chen Ming , Li Dejiao
Published: January 2010

Objective. This is prospective randomized control trial to compare the mean keratometric corneal astigmatism diopter power (not surgical induced astigmatism) among preop and one-month and three-month postop phacoemulcification of either a clear temporal corneal incision or a superior scleral tunnel Incision, using only keratometric astigmatic power reading to evaluate the difference between the two cataract surgery incisions.Methods. 120 patients (134 eyes) underwent phacoemulcification were randomly assigned to two groups: Group A, the clear temporal corneal incision group, and Group B, the superior scleral tunnel incision group. SPSS11.5 Software was used for statistical analysis to compare the postsurgical changes of cornea astigmatism on keratometry.Results. The changes of corneal astigmatic diopter in Groups A and B after 3 month postop from keratometric reading were 1.04 + 0.76 and 0.94 + 0.27, respectively ( .05), which showed no statistic significance difference.Conclusion. The incision through either temporal clear cornea or superior scleral tunnel in phacoemulcification shows no statistic difference in astigmatism change on keratometry 3-month postop.
Inversion of the Laplace Transform from the Real Axis Using an Adaptive Iterative Method
Authors: Indratno Sapto W. , Ramm Alexander G.
Published: January 2010

A new method for inverting the Laplace transform from the real axis is formulated. This method is based on a quadrature formula. We assume that the unknown function f(t) is continuous with (known) compact support. An adaptive iterative method and an
adaptive stopping rule, which yield the convergence of the approximate
solution to f(t), are proposed in this paper.
DTI Parameter Optimisation for Acquisition at 1.5T: SNR Analysis and Clinical Application
Authors: Laganà M. , Rovaris M. , Ceccarelli A. , Venturelli C. , Marini S. , Baselli G.
Published: January 2010

Background. Magnetic Resonance (MR) diffusion tensor imaging (DTI) is able to quantify in vivo tissue microstructure properties and to detect disease related pathology of the central nervous system. Nevertheless, DTI is limited by low spatial resolution associated with its low signal-to-noise-ratio (SNR).Aim. The aim is to select a DTI sequence for brain clinical studies, optimizing SNR and resolution.Methods and Results. We applied 6 methods for SNR computation in 26 DTI sequences with different parameters using 4 healthy volunteers (HV). We choosed two DTI sequences for their high SNR, they differed by voxel size and b-value. Subsequently, the two selected sequences were acquired from 30 multiple sclerosis (MS) patients with different disability and lesion load and 18 age matched HV. We observed high concordance between mean diffusivity (MD) and fractional anysotropy (FA), nonetheless the DTI sequence with smaller voxel size displayed a better correlation with disease progression, despite a slightly lower SNR. The reliability of corpus callosum (CC) fiber tracking with the chosen DTI sequences was also tested.Conclusion. The sensitivity of DTI-derived indices to MS-related tissue abnormalities indicates that the optimized sequence may be a powerful tool in studies aimed at monitoring the disease course and severity.
Oscillation Criteria for Even Order Neutral Equations with Distributed Deviating Argument
Authors: Zhang Siyu , Meng Fanwei
Published: January 2010

We present new oscillation criteria for the even order neutral delay differential equations with
distributed deviating argument
,
where Z(t) = x(t) + q(t)x(t − τ). Assumptions in our theorems are less restrictive, whereas the
proofs are significantly simpler compared to those by Wang et al. (2005).
Identification and Quantification of Genomic Repeats and Sample Contamination in Assemblies of 454 Pyrosequencing Reads
Authors: Nederbragt Alexander J. , Rounge Trine Ballestad , Kausrud Kyrre L. , Jakobsen Kjetill S.
Published: January 2010

Contigs assembled from 454 reads from bacterial genomes demonstrate a range of read depths, with a number of contigs having a depth that is far higher than can be expected. For reference genome sequence datasets, there exists a high correlation between the contig specific read depth and the number of copies present in the genome. We developed a sequence of applied statistical analyses, which suggest that the number of copies present can be reliably estimated based on the read depth distribution in de novo genome assemblies. Read depths of contigs of de novo cyanobacterial genome assemblies were determined, and several high read depth contigs were identified. These contigs were shown to mainly contain genes that are known to be present in multiple copies in bacterial genomes. For these assemblies, a correlation between read depth and copy number was experimentally demonstrated using real-time PCR. Copy number estimates, obtained using the statistical analysis developed in this work, are presented. Per-contig read depth analysis of assemblies based on 454 reads therefore enables de novo detection of genomic repeats and estimation of the copy number of these repeats.
Additionally, our analysis efficiently identified contigs stemming from sample contamination, allowing for their removal from the assembly.
Strategic Approach to Validating Methylated Genes as Biomarkers for Breast Cancer
Authors: Wang Wendy , Srivastava Sudhir
Published: January 2010

Although the potential of biomarkers to aid in the early detection, diagnosis, prevention, and treatment of breast cancer is broadly recognized and numerous biomarker candidates have been reported in the literature, few molecular markers have been adopted into clinical use to date. To address this lack of translation of biomarkers from the bench to clinical practice, the Cancer Biomarkers Research Group in the Division of Cancer Prevention of the National Cancer Institute organized a meeting, “Strategic Discussion on Biomarkers for Breast Cancer,” which was held at the Fred Hutchinson Cancer Research Center on September 14, 2008. Participants included industry leaders, basic and physician scientists, and National Cancer Institute program staff. The objectives of this strategic discussion were to define clinical uses and needed performance characteristics of biomarkers; to identify novel approaches to discover and validate breast cancer biomarkers, particularly those with improved chances of being clinically useful; and to identify candidate DNA methylation markers that could be taken forward for validation. Participants presented and recommended methylation biomarkers suitable for initiating collaborative projects to evaluate the markers for future clinical application. This commentary summarizes their discussions and recommendations and the rationale for initiating specific projects to validate DNA methylation biomarkers of breast cancer. Cancer Prev Res; 3(1); 16–24
Sulindac and Sulindac Metabolites in Nipple Aspirate Fluid and Effect on Drug Targets in a Phase I Trial
Authors: Thompson Patricia A. , Hsu Chiu-Hsieh , Green Sylvan , Stopeck Alison T. , Johnson Karen , Alberts David S. , Chow H-H. Sherry
Published: January 2010

Regular use of nonsteroidal anti-inflammatory drugs (NSAID) has been associated with reduced risk of breast cancer. Sulindac, a nonselective NSAID with both cyclooxygenase-2–dependent and –independent activities, is a candidate for breast chemoprevention. We conducted a phase Ib trial in 30 women at increased risk for breast cancer to evaluate the breast tissue distribution of sulindac at two dose levels (150 mg daily and 150 mg twice daily for 6 weeks), using nipple aspirate fluid (NAF) as a surrogate of breast tissue drug exposure. We also explored the effect of sulindac on drug-induced biomarkers in NAF. We show that sulindac and its metabolites partition to human breast as measured by NAF levels. Sulindac intervention did not decrease 13,14-dihydro-15-keto prostaglandin A2, a stable derivative of prostaglandin E2, in NAF, but exposure was associated with a significant trend towards higher levels of growth differentiation factor 15 in NAF in women receiving 150 mg twice daily (P = 0.038). These results are the first to show partitioning of sulindac and metabolites to human breast tissue and the first evidence for a potential dose-dependent effect of sulindac on growth differentiation factor 15 levels in NAF. Cancer Prev Res; 3(1); 101–7
Beyond the Scalpel: Targeting Hedgehog in Skin Cancer Prevention
Authors: Rudin Charles M.
Published: January 2010

This perspective places the article by Tang et al. in this issue of the journal (beginning on page 25) in the context of recent work defining the hedgehog signaling pathway as a central etiologic factor and as a therapeutic target in basal cell cancer. Tang et al. show that inhibition of cyclooxygenase activity, either genetically (in a relevant mouse model) or pharmacologically (in the mouse and in patients highly predisposed to develop basal cell skin cancers), may suppress basal cell carcinogenesis. This new study of cyclooxygenase inhibition, together with recent data on the efficacy of hedgehog pathway inhibition, offers new hope for patients at a high risk for basal cell cancer. Cancer Prev Res; 3(1); 1–3
Translating Cyclooxygenase Signaling in Patch Heterozygote Mice into a Randomized Clinical Trial in Basal Cell Carcinoma
Authors: Arbiser Jack L.
Published: January 2010

This different perspective on Tang et al. (beginning on p. 25 in this issue of the journal) discusses the pivotal role of cyclooxygenase (COX) signaling in the pathogenesis of basal cell carcinoma (BCC). These investigators conducted elegant experiments showing increased BCC burden in patch heterozygous mice overexpressing COX-2 in the epidermis. Genetic deletion of COX-1 or COX-2 resulted in a robust decrease in BCC burden in patch heterozygote mice. They then studied pharmacologic COX inhibition in mice and humans with loss of patch, finding a trend in humans toward decreased BCC burden. This finding has implications for public health. Cancer Prev Res; 3(1); 4–7
Syndecan-1 Amplifies Angiotensin II–Induced Cardiac Fibrosis
Authors: Schellings Mark W.M. , Vanhoutte Davy , van Almen Geert C. , Swinnen Melissa , Leenders Joost J.G. , Kubben Nard , van Leeuwen Rick E.W. , Hofstra Leo , Heymans Stephane , Pinto Yigal M.
Published: January 2010

Syndecan-1 (Synd1) is a transmembrane heparan sulfate proteoglycan that functions as a coreceptor for various growth factors and modulates signal transduction. The present study investigated whether Synd1, by affecting growth factor signaling, may play a role in hypertension-induced cardiac fibrosis and dysfunction. Expression of Synd1 was increased significantly in mouse hearts with angiotensin II–induced hypertension, which was spatially related to cardiac fibrosis. Angiotensin II significantly impaired fractional shortening and induced cardiac fibrosis in wild-type mice, whereas these effects were blunted in Synd1-null mice. Angiotensin II significantly increased cardiac expression of connective tissue growth factor and collagen type I and III in wild-type mice, which was blunted in Synd1-null mice. These findings were confirmed in vitro, where angiotensin II induced the expression of both connective tissue growth factor and collagen I in fibroblasts. The absence of Synd1 in either Synd1-null fibroblasts, after knockdown of Synd1 by short hairpin RNA, or after inhibition of heparan sulfates by protamine attenuated this increase, which was associated with reduced phosphorylation of Smad2. In conclusion, loss of Synd1 reduces cardiac fibrosis and dysfunction during angiotensin II–induced hypertension.
Cyclin-Dependent Kinase 5 Phosphorylates Endothelial Nitric Oxide Synthase at Serine 116
Authors: Cho Du-Hyong , Seo Jungwon , Park Jung-Hyun , Jo Chulman , Choi Yoon Jung , Soh Jae-Won , Jo Inho
Published: January 2010

Nitric oxide (NO) production in endothelial cells (EC) is regulated by multisite phosphorylation of specific serine and threonine residues in endothelial NO synthase (eNOS). Among these, eNOS-Ser116 is phosphorylated in the basal state, and its phosphorylation contributes to basal NO production. Here, we investigated the mechanism by which eNOS-Ser116 is phosphorylated during the basal state using bovine aortic EC. Although a previous study suggested that protein kinase C was involved in eNOS-Ser116 phosphorylation, overexpression of various protein kinase C isoforms did not affect eNOS-Ser116 phosphorylation. An in silico analysis using a motif scan revealed that the eNOS-Ser116 residue might be a substrate for proline-directed protein kinases. Roscovitine, a specific inhibitor of cyclin-dependent kinase (CDK), 1, 2, and 5, but not an inhibitor of mitogen-activated protein kinase kinase or glycogen synthase kinase 3β, inhibited eNOS-Ser116 phosphorylation dose dependently. Furthermore, purified CDK1, 2, or 5 directly phosphorylated eNOS-Ser116 in vitro. Ectopic expression of the dominant-negative CDK5 but not dominant-negative CDK1 or dominant-negative CDK2 repressed eNOS-Ser116 phosphorylation and increased NO production. In addition, CDK5 activity was detected in bovine aortic EC, and coimmunoprecipitation and confocal microscopy studies revealed a colocalization of eNOS and CDK5. Cotransfection of CDK5 and p25, the specific CDK5 activator, increased eNOS-Ser116 phosphorylation and decreased NO production, but its parent molecule, p35, and p39, another activator, were not detected in bovine aortic EC, which suggests the existence of a novel CDK5 activator. Overall, this is the first study to find that CDK5 is a physiological kinase responsible for eNOS-Ser116 phosphorylation and regulation of NO production.