bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental Determination of Water Hammer Pressure Transients During Vapor Collapse
Authors: Leishear Robert A.
Published: July 2008

Pressures were measured during water hammer in a steam condensate system. The water hammer mechanism was verified to be vapor collapse in the piping as a pump started, using an ultrasonic measurement of pipe fluid levels. Before the pump started, an overhead pipe was partially full of water. When the pump started, the pipe became filled nearly instantaneously. The vapor collapse created audible water hammers and resultant shock waves in the piping. The shock waves were eliminated by controlling the pump start up using a variable frequency drive (VFD). A slow start prevents the sudden collapse of the vapor space and eliminates the water hammer.
Measurement of Thermal Ratcheting Strain on the Structures by the Laser Speckle Method
Authors: Watanabe Daigo , Chuman Yasuharu , Otani Tomomi , Shibamoto Hiroshi , Inoue Kazuhiko , Kasahara Naoto
Published: July 2008

Prevention of thermal ratcheting is an important problem for high temperature components of fast breeder reactors that are subjected to cyclic thermal loads. To clarify ratcheting behaviors, structural model tests were planned. Strain measurement is important for understanding the thermal ratcheting phenomenon The conventional measurement by strain gauge is difficult at high temperature. Then, Laser speckle strain measurement system using the dual-beam set-up was developed to apply to high temperature structural model tests. This system was applied to the thermal ratcheting tests, which demonstrated the actual operative conditions of reactor vessels. Through comparison with uniaxial test results obtained by extensometers, the laser speckle method was verified. Measured data of structural model tests were utilized to certify the guidelines of inelastic analysis for design, which provide prediction method of strain in components of fast reactor.
Risk-Based Inspection Analysis for High Pressure Hydrogenation Cracking Unit
Authors: Zhao Jian-Ping
Published: July 2008

High pressure hydrogenation cracking unit is the core equipment system in the aromatic plant, which is subjected simultaneously to the action of hydrogen and high pressure and high temperature. In this paper, quantitative analysis method of RBI was carried out by Orbit-Onshore software, which was developed by DNV corporation. In API 581, the risk situation for a certain equipment unit were classified into four grades, such as low risk grade and medium risk grade and medium-high risk grade and high grade, which is expressed as risk matrix. The whole risk distribution of 553 equipment and piping items was obtained, and in which the hydrocracking reactors and the reactor effluent air coolers are belong to ‘medium-high risk’ grade. Based on the RBI results, an optimum inspection plan was developed by the author to reduce the risk level for the hydrogenation cracking unit. It is concluded that the optimum inspection plan was completely satisfied with the engineering specification of the aromatic plant, after the validation of the inspection activity in 2004.
Studies on Pipeline Risk Management in China
Authors: Gao Fuqing , Zhang Jixian , Yuan Lihai
Published: July 2008

The safety of oil & gas pipelines is vital to the environment, people and properties. In this paper, the pipeline risk management is summarized. A management plan of pipeline integrity adopted worldwide based on intelligent inspection is introduced, and the actuality of pipeline risk management in China and the problems are mentioned. An integrated solution which emphasizes that the legislation on pipeline safety is the safeguard of it, to enhance pipeline safety management is the key for it and to design pipeline databases and risk assessment system based on digital computerized technology is the foundation of pipeline safety, is proposed. Only these three aspects are closely worked in, can the pipeline risk be effectively controlled, so that it is possible to reduce pipeline risk in maximum and keep pipelines operating safely and efficiently.
Investigation of the Mechanical Properties of St. Lawrence River Ice
Authors: Gold L. W. , Krausz A. S.
Published: July 2008

Observations are reported on the stress–strain behavior at −9.5 ± 0.5 °C of four types of ice obtained from the St. Lawrence River. The ice was subject to nominal rates of strain covering the range 2.1 × 10−5 min−1 to 5.8 × 10−2 min−1. A ductile-to-brittle transition was observed for strain rate of about 10−2 min−1. In the ductile range the four types had an upper yield stress that increased with strain rate according to a power law.
A Study of the Cementation Bonds of the Sensitive Clays of the Outardes River Region
Authors: Loiselle André , Massiera Michel , Sainani Usha R.
Published: July 2008

The various factors affecting the mechanical behavior of a cemented silty clay are looked upon in this article.Chemical treatments with a 0.2 N solution of EDTA to remove cementing agents and with 0.6- or 35-g/l solutions of NaCl to study the influence of salinity were carried out on soil specimens. The various treatments were carried out by permeating the solutions through the specimen until the electrical conductivity of the outflow equaled that of the inflow. The pre-consolidation pressure was observed to vary from 2.4 kg/m2 for the specimens treated with EDTA and 0.6 g/l NaCl to 5.0 kg/cm2 for the specimens treated with 35 g/l NaCl, while the compression index remained essentially constant for all specimens but one. It is shown that the compressibility of a clay is dependent on both its stress and its environmental history.Shear strength tests by conventional triaxial compression and by simple shear device were also carried out on both chemically treated and untreated soil specimens. It was concluded that the removal of the cementing agents slightly changed the stiffness of the soil structure. While it apparently did not change the results at failure, it was concluded that cementing bonds most likely were broken at very small strains, resulting in no substantial increase of strength except under very small consolidation pressure.
Transfer of Heaving Forces by Adfreezing to Columns and Foundation Walls in Frost-Susceptible Soils
Authors: Penner E. , Gold L. W.
Published: July 2008

The paper gives results of field studies on uplift forces on small-diameter columns of steel, concrete, and wood caused by adfreezing in frost-susceptible Leda clay. Adfreeze strength values would appear to be highest for steel and concrete, followed closely by wood. The heaving pattern and the heaving force transmitted are shown to be different for long foundation walls than for isolated columns. This compares favorably with the deformation pattern induced in an ice cover around offshore structures, during a change in water level. Attention is also given to the relative movement of the heaving soil with respect to the structure and the influence of the heave pattern on the transmission of forces.
A Rheological Model for Soil-structure Interaction under Cyclic Loading
Authors: Levinson Mark , Wilson Nyal E.
Published: July 2008

A rheological model is given which is capable of representing the continuing secondary foundation settlements reported in certain field observations of structures experiencing large variations in live load; similar observations have been made in the laboratory for specimens subjected to repeated loading. It is expected that the given model will prove useful in the long-time stress analysis of flexible structures, such as oil tanks, which are subjected to large variations in load.
Usage, requirements and features of slope stability computer software (Canada, 1977)
Authors: Fredlund D. G.
Published: July 2008

A survey of Canadian universities and consulting engineering firms was conducted to ascertain the present status of slope stability software usage in Canada. The results indicate that most universities have access to at least one slope stability computer program. However, there is limited usage of computer programs as a teaching tool at the undergraduate or graduate level. In general, the programs are poorly documented and not distributed. Consulting engineering firms indicate that more education on the relationship between the various methods of slices, on available software and its application to practical problems would be beneficial. The most commonly used procedures are the simplified Bishop method for circular failure surfaces and the Morgenstern–Price method for noncircular failure surfaces.Several well-documented slope stability computer programs are available to the geotechnical engineer at the cost of reproduction. The source for obtaining the programs is listed in the paper. Computer programs are available for all the commonly used methods of slices and the features of each program are also summarized in the paper.
The Denholm landslide, Saskatchewan. Part I: Geology
Authors: Christiansen E. A.
Published: July 2008

The Denholm landslide, whose surface is composed of scarps, ridges, and elongated depressions, is 160 m high, 2000 m wide, and up to 100 m thick. The shear zone is in silty, montomorillonitic clay of the upper part of the Lea Park Formation and Upper Colorado Group unit. The Upper Cretaceous Judith River Formation and the Quaternary Empress, Sutherland, and Saskatoon groups were affected by the landslide. Although these sediments were fractured and gravity faulted by tension when the landslide moved, they can be readily traced through the landslide, particularly the upper part. The scarps (gravity faults), ridges (horsts), and elongated depressions (grabens) are the surface expression of tension resulting from the stretching of beds during the landslide.The movement of the landslide is thought to have started when the North Saskatchewan spillway eroded to the level of the present shear zone about 11 000 years ago (established by radiocarbon dating) and is believed to have stopped in recent time. During this time, it moved about 390 m across the North Saskatchewan River alluvium at an average rate of 35 mm per year. As the landslide moved across the valley, it encountered deposition of alluvium at an average rate of about 2.4 mm per year which resulted in the curved shear zone on the alluvium. Keywords: retrogressive landslide, shale-alluvium, displacement, rate, age.
A combined hardening model of anisotropically consolidated cohesive soils
Authors: Hirai Hiroyoshi , Kamei Takeshi
Published: July 2008

A model introduced in the present paper is capable of describing the mechanical behaviour of anisotropically consolidated cohesive soils reasonably well. The salient features of the proposed model are summarized as follows: (i) generalized forms of the Cambridge models are given to both yield function and plastic potential; (ii) a combination of isotropic and kinematic hardening is used; (iii) a nonassociated-flow rule is proposed; (iv) the isotropic hardening involves plastic work not only related to volumetric change but also to deviatoric deformation; (v) the translation of the yield surface is specified by extending Ziegler's rule of kinematic hardening; (vi) the constitutive model has versatility and flexibility to describe expansion, translation, and rotation of a yield surface in stress space. Several undrained triaxial tests of anisotropically consolidated cohesive soils are simulated, and good agreement is observed between simulation and experimental data. Key words: anisotropy, dilatancy, cohesive soil, consolidated undrained shear, constitutive equation, stress-strain curve, pore pressure - strain curve, effective-stress path.
An interpretation of ground movements recorded during construction of the Donkin-Morien tunnel
Authors: Pelli F. , Kaiser P. K. , Morgenstern N. R.
Published: July 2008

A tunnel excavated by a tunnel boring machine was monitored extensively by means of extensometers installed near the tunnel face. Consequently, the three-dimensional state existing at the time of installation must be considered for the interpretation of the monitoring data. Results from three-dimensional finite element simulations are used to back-calculate rock mass strength and deformation properties. The purpose of this study was to establish and test various approaches of back-analysis. Results are compared with field and laboratory measurements. On the basis of these analyses, the paper provides guidance on how field data can be used for back-analysis purposes even when the ground behaves in a nonelastic manner. Key words: tunnelling, monitoring, tunnel boring, back-analysis, nonlinearity.
Computer simulation of crosswell seismic propagation and determination of elastic parameters
Authors: Singh R. P. , Chandra S. , Jha A. K. , Singh Y. P.
Published: July 2008

The potential usefulness of crosswell seismic measurement in determining the dynamic elastic parameters of subsurface material is demonstrated. It is shown that tomographic inversion of seismic wave travel time for a combined borehole to borehole and borehole to surface configuration provides the characteristics of shape, size, and orientation of anomalies. The travel time for each source and receiver paths are computed and are inverted to determine the elastic parameters. The procedure described in this paper can prove to be economic and less time consuming in mapping anomalous regions such as soft pockets, tunnels, and buried pipes that are quite often encountered by civil engineers during site selection for large construction projects. Key words: crosshole measurement, tomographic inversion, dynamic parameters, site investigation, seismic investigation.
Temperature measurements in geotechnical studies using low-noise, high-resolution digital techniques
Authors: Woodbury Allan D. , Narod B. , Chandra B. , Bennest J. R.
Published: July 2008

In this paper we show how temperatures can be of use as a normal well-logging tool and as an aid in site hydrogeological analysis. A back-portable, digital temperature-logging system has been developed. The system consists of a digital probe, a small surface unit, a back-portable cable reel, and a lap-top computer. The probe is 2.54 cm outside diameter and has been used in 3.05 cm inside diameter tubing. The overall accuracy of the probe is ±0.01 °C in the range −40 to + 40 °C. Power consumption is less than 30 mA at 12 V direct current. The probe's capability and the thermal methodology are demonstrated at a Manitoba Hydro project site along the Nelson River in northern Manitoba. The thermal regime of the site displays a myriad of effects, from permafrost to transient-advective environments. Surface temperatures are affected by permafrost, particularly through the postglacial deposits. Permafrost is less evident towards the river on the north side, undoubtedly due to warming effects from river and ice staging. Although only one set of temperatures has been obtained at the site, the inclusion of the thermal data aided significantly in identifying effects that otherwise would have been missed in a purely hydrogeologic investigation. Key words: digital thermal measurements, geotechnical studies, permafrost, groundwater.
A pseudo-two-dimensional seismic analysis of earth dams
Authors: Soulié M. , Touileb B. N. , Silvestri V.
Published: July 2008

This paper describes the development of a pseudo-two-dimensional model for the prediction of the seismic responses of earth dams of heterogeneous cross sections. The model, called DESRA-2.MOD, has been applied to both the total stress and the effective stress responses of a dam subjected to earthquake loading. In the case of the total stress analysis, the DESRA-2.MOD model provides results that approximate reasonably well those obtained by means of the more precise two-dimensional QUAD-4 model. As for the effective stress analysis, it is shown that zones of liquefaction develop during the earthquake and propagate through the dam, especially in the upstream region. Key words: one-dimensional model, seismic analysis, earth dams, heterogeneous cross sections, total stress, effective stress, liquefaction.
In situ determination of a rock mass modulus using a high resolution tiltmeter
Authors: Saleh Bassam , Malkawi Abdallah I Husein , Blum Pierre A
Published: July 2008

A very high resolution tiltmeter (108 rad, 0.002 s) developed by P.A. Blum, in 1957 was used to establish a new approach to directly evaluate the in situ average elastic rock-mass modulus. Five tiltmeters were installed on the facades of the Louvre museum to study the deformations induced by internal structural work and by the impact of the Paris metro traffic movement. The measured data from the tiltmeter were used to determine the elastic rock modulus of the museum's foundation using the Boussinesq model. The results obtained by the developed approach are consistent with the typical elastic rock-mass modulus for the rock found in the museum's foundations.

Key words: rock-mass modulus, tiltmeter, deformation, Boussinesq model.
PERMANENCE AND COMPLEXITY OF THE ECO-EPIDEMIOLOGICAL MODEL WITH IMPULSIVE PERTURBATION
Authors: SUN SHULIN , CHEN LANSUN
Published: July 2008

In this paper, we investigate the eco-epidemiological model with impulsive perturbation. Using Floquet theory and small amplitude perturbation method, we prove that the boundary periodic solution is asymptotically stable if the impulsive parameter satisfies some conditions. Moreover, the permanence of the system is discussed by analytical method. Finally, the complexity of the system is verified by numerical simulation.
OPTIMAL HARVESTING PROBLEM FOR AN AGE-DEPENDENT n-DIMENSIONAL COMPETING SYSTEM WITH DIFFUSION
Authors: LUO ZHIXUE , HE ZE-RONG
Published: July 2008

In this work, optimal harvesting policy for an age-dependent and spatial diffusion n-dimensional competing species is discussed. The existence and uniqueness of non-negative solution to the system are investigated by using the fixed point theorem. The existence of optimal control strategy is discussed and optimality conditions are obtained. Our results extend some known criteria.
TWO DIFFERENT VACCINATION STRATEGIES IN AN SIR EPIDEMIC MODEL WITH SATURATED INFECTIOUS FORCE
Authors: PEI YONGZHEN , LIU SHAOYING , CHEN LANSUN , WANG CHUNHUA
Published: July 2008

Two different vaccination and treatment strategies in the SIR epidemic model with saturation infectious force are analyzed. With the continuous vaccination and treatment, it is obtained that the disease free equilibrium and endemic equilibrium are globally asymptotically stable by using Lassall theorem and Pioncare–Bendixon trichotomy. Moreover, with pulse vaccination and treatment at different time, the dynamics of the epidemic model is globally investigated by using Floquet theory and comparison theorem of impulsive differential equation and analytic method. We obtain the conditions of global asymptotical stability of the infection-free periodic solution and permanence of the model. Finally, we compare the two different vaccination and treatment strategies, and obtain that the elimination of disease is independent of treatment in the case of the pulse vaccination.
THE BIRTH AND DEATH EQUATION OF VIRUS SPREADING
Authors: GUO BEN-HUA , CAI SHAO-HONG , ZHU JIA-QIANG
Published: July 2008

Based on the complex network and non-equilibrium statistic theory, the birth and death equation (BDE) is proposed for the virus spreading on biological networks. This equation, in which the Susceptible Infected Susceptible model is extended, can predict the distribution rule of infection density by generating function. It is a better approach to a real infection process.
PERMANENCE AND GLOBAL STABILITY IN AN IMPULSIVE LOTKA–VOLTERRA N-SPECIES COMPETITIVE SYSTEM WITH BOTH DISCRETE DELAYS AND CONTINUOUS DELAYS
Authors: MENG XINZHU , CHEN LANSUN
Published: July 2008

In this paper, we formulate a robust impulsive Lotka–Volterra n-species competitive system with both discrete delays and continuous delays. Our results in this paper indicate that under the appropriate linear bounded impulsive perturbations, the impulsive delay Lotka–Volterra system remains the original permanence and globally asymptotical stability of the nonimpulsive delay Lotka–Volterra system. We show that the conditions for the permanence and globally asymptotical stability of the system depend on time delays, so, we call it "profitless".
GLOBAL ATTRACTIVITY OF A STAGE-STRUCTURE VARIABLE COEFFICIENTS PREDATOR-PREY SYSTEM WITH TIME DELAY AND IMPULSIVE PERTURBATIONS ON PREDATORS
Authors: JIAO JIANJUN , CHEN LANSUN
Published: July 2008

In this work, we consider a delayed stage-structured variable coefficients predator-prey system with impulsive perturbations on predators. By using the discrete dynamical system determined by stroboscopic map and the standard comparison theorem, we obtain the sufficient conditions which guarantee the global attractivity of prey-extinction periodic solution of the investigated system. We also prove that all solutions of the system are uniformly ultimately bounded. Our results provide reliable tactic basis for the practical pest management.
A MONOTONE-ITERATIVE METHOD FOR FINDING PERIODIC SOLUTION OF AN IMPULSIVE DIFFERENTIAL EQUATIONS AND APPLICATION
Authors: DOU JIAWEI
Published: July 2008

In this paper, using the method of upper and lower solutions and its associated monotone iterations, we establish a new monotone-iterative scheme for finding periodic solutions of an impulsive differential equations. This method leads to the existence of maximal and minimal periodic solutions which can be computed from a linear iteration process in the same fashion as for impulsive differential equations initial value problem. This method is constructive and can be used to develop a computational algorithm for numerical solution of the periodic impulsive system. Our existence result improves a result established in [1]. The result is applied to a model of mutualism of Lotka–Volterra type which involves interactions among a mutualist-competitor, a competitor and a mutualist, the existence of positive periodic solutions of the model is obtained.
Using Mixed Precision for Sparse Matrix Computations to Enhance the Performance while Achieving 64-bit Accuracy
Authors: Buttari Alfredo , Dongarra Jack , Kurzak Jakub , Luszczek Piotr , Tomov Stanimir
Published: July 2008

By using a combination of 32-bit and 64-bit floating point arithmetic, the performance of many sparse linear algebra algorithms can be significantly enhanced while maintaining the 64-bit accuracy of the resulting solution. These ideas can be applied to sparse multifrontal and supernodal direct techniques and sparse iterative techniques such as Krylov subspace methods. The approach presented here can apply not only to conventional processors but also to exotic technologies such as Field Programmable Gate Arrays (FPGA), Graphical Processing Units (GPU), and the Cell BE processor.
Microtubule Dynamics in Cell Division: Exploring Living Cells with Polarized Light Microscopy
Authors: Inoué Shinya
Published: July 2008

This Perspective is an account of my early experience while I studied the dynamic organization and behavior of the mitotic spindle and its submicroscopic filaments using polarized light microscopy. The birefringence of spindle filaments in normally dividing plant and animal cells, and those treated by various agents, revealed (a) the reality of spindle fibers and fibrils in healthy living cells; (b) the labile, dynamic nature of the molecular filaments making up the spindle fibers; (c) the mode of fibrogenesis and action of orienting centers; and (d) force-generating properties based on the disassembly and assembly of the fibrils. These studies, which were carried out directly on living cells using improved polarizing microscopes, in fact predicted the reversible assembly properties of microtubules.
Learning from Others: Children's Construction of Concepts
Authors: Gelman Susan A.
Published: July 2008

Much of children's knowledge is derived not from their direct experiences with the environment but rather from the input of others. However, until recently, the focus in studies of concept development was primarily on children's knowledge, with relatively little attention paid to the nature of the input. The past 10 years have seen an important shift in focus. This article reviews this approach, by examining the nature of the input and the nature of the learner, to shed light on early conceptual learning. These findings argue against the simple notion that conceptual development is either supplied by the environment or innately specified, and instead demonstrate how the two work together. The implications for how children reconcile competing belief systems are also discussed.
Dysregulated human renin expression in transgenic mice carrying truncated genomic constructs: evidence supporting the presence of insulators at the renin locus
Authors: Zhou Xiyou , Weatherford Eric T. , Liu Xuebo , Born Ella , Keen Henry L. , Sigmund Curt D.
Published: July 2008

We previously generated transgenic mice carrying a large P1 artificial chromosome (PAC160) encompassing a 160-kb segment containing the human renin gene, two upstream genes, and one downstream gene. We also previously generated mutant PAC160 constructs lacking the distal enhancer and concluded it is required to maintain baseline expression of human renin, but is not required for tissue-specific, cell-specific, and regulated expression of renin in vivo. We now report two additional transgenic lines carrying random truncations of PAC160 upstream of the renin gene. Southern and PCR mapping studies indicate that the truncation break points in the two lines are located ∼10.4 and 2.5 kb upstream of the renin gene causing a deletion of all DNA upstream of the break. We tested the hypothesis that large-scale deletion of DNA upstream of the human renin gene including the enhancer would cause dysregulation of human renin expression. Phenotypically, these truncations cause a severe dysregulation of human renin expression, but remarkably, a preservation of the normal tissue-specific expression of the human ethanolamine kinase 2 (ETNK2) gene which lies immediately downstream of renin. Several functional binding sites for CTCF, a mammalian insulator protein, were identified in and around the renin and ETNK2 loci by gel shift and chromatin immunoprecipitation. We conclude that there are sequences in and around the renin and ETNK2 loci which act as boundaries between neighboring genes which insulate them from each other. The study illustrates the value of taking a much wider genomic perspective when studying mechanisms regulating gene expression.
Specificity of Inferior Olive Response to Stimulus Timing
Authors: Liu T. , Xu D. , Ashe J. , Bushara K.
Published: July 2008

The inferior olive is the sole source of the climbing fiber system, one of the two major afferent systems of the cerebellum; however, its exact role remains unknown. A longstanding hypothesis is that the inferior olive with its unique intrinsic rhythmic firing properties mediates motor timing. However, direct evidence linking the inferior olive to timing behavior has been difficult to demonstrate in animal or human studies likely due to the inhibition of inferior olive responses by self-produced movement. Here we used event-related functional magnetic resonance imaging (fMRI) and a perceptual task that dissociates the temporal from nontemporal attributes of sensory input. Subjects were asked to attend to rhythmically occurring identical visual stimuli and to detect a change in their timing, spatial orientation, or color. Inferior olive activation was seen only when perceiving a change in stimulus timing. These results are consistent with animal studies demonstrating that the inferior olive is especially sensitive to “unexpected” sensory events and further provide evidence supporting the specificity of the inferior olive response to stimulus timing. The results are consistent with the view that the inferior olive and the climbing fiber system mediate the encoding of temporal information required for both motor and nonmotor cognitive processes.
Parvalbumin-Positive Basket Interneurons in Monkey and Rat Prefrontal Cortex
Authors: Povysheva N. V. , Zaitsev A. V. , Rotaru D. C. , Gonzalez-Burgos G. , Lewis D. A. , Krimer L. S.
Published: July 2008

Differences in the developmental origin and relative proportions of biochemically distinct classes of cortical neurons have been found between rodents and primates. In addition, species differences in the properties of certain cell types, such as neurogliaform cells, have also been reported. Consequently, in this study we compared the anatomical and physiological properties of parvalbumin (PV)-positive basket interneurons in the prefrontal cortex of macaque monkeys and rats. The somal size, total dendritic length, and horizontal and vertical spans of the axonal arbor were similar in monkeys and rats. Physiologically, PV basket cells could be identified as fast-spiking interneurons in both species, based on their short spike and high-frequency firing without adaptation. However, important interspecies differences in the intrinsic physiological properties were found. In monkeys, basket cells had a higher input resistance and a lower firing threshold, and they generated more spikes at near-threshold current intensities than those in rats. Thus monkey basket cells appeared to be more excitable. In addition, rat basket cells consistently fired the first spike with a substantial delay and generated spike trains interrupted by quiescent periods more often than monkey basket cells. The frequency of miniature excitatory postsynaptic potentials in basket cells was considerably higher in rats than that in monkeys. These differences between rats and monkeys in the electrophysiological properties of PV-positive basket cells may contribute to the differential patterns of neuronal activation observed in rats and monkeys performing working-memory tasks.
AMPA Receptor-Dependent H2O2 Generation in Striatal Medium Spiny Neurons But Not Dopamine Axons: One Source of a Retrograde Signal That Can Inhibit Dopamine Release
Authors: Avshalumov Marat V. , Patel Jyoti C. , Rice Margaret E.
Published: July 2008

Dopamine-glutamate interactions in the striatum are critical for normal basal ganglia-mediated control of movement. Although regulation of glutamatergic transmission by dopamine is increasingly well understood, regulation of dopaminergic transmission by glutamate remains uncertain given the apparent absence of ionotropic glutamate receptors on dopaminergic axons in dorsal striatum. Indirect evidence suggests glutamatergic regulation of striatal dopamine release is mediated by a diffusible messenger, hydrogen peroxide (H2O2), generated downstream from glutamatergic AMPA receptors (AMPARs). The mechanism of H2O2-dependent inhibition of dopamine release involves activation of ATP-sensitive K+ ( KATP) channels. However, the source of modulatory H2O2 is unknown. Here, we used whole cell recording, fluorescence imaging of H2O2, and voltammetric detection of evoked dopamine release in guinea pig striatal slices to examine contributions from medium spiny neurons (MSNs), the principal neurons of striatum, and dopamine axons to AMPAR-dependent H2O2 generation. Imaging studies of H2O2 generation in MSNs provide the first demonstration of AMPAR-dependent H2O2 generation in neurons in the complex brain-cell microenvironment of brain slices. Stimulation-induced increases in H2O2 in MSNs were prevented by GYKI-52466, an AMPAR antagonist, or catalase, an H2O2 metabolizing enzyme, but amplified by mercaptosuccinate (MCS), a glutathione peroxidase inhibitor. By contrast, dopamine release evoked by selective stimulation of dopamine axons was unaffected by GYKI-52466 or MCS, arguing against dopamine axons as a significant source of modulatory H2O2. Together, these findings suggest that glutamatergic regulation of dopamine release via AMPARs is mediated through retrograde signaling by diffusible H2O2 generated in striatal cells, including medium spiny neurons, rather than in dopamine axons.
Quantitative trait loci for impaired glucose tolerance in nondiabetic SM/J and A/J mice
Authors: Hada Natsuko , Kobayashi Misato , Fujiyoshi Masato , Ishikawa Akira , Kuga Masako , Nishimura Masahiko , Ebihara Shizufumi , Ohno Tamio , Horio Fumihiko
Published: July 2008

The SMXA-5 recombinant inbred strain, which was established from nondiabetic parental SM/J and A/J mice, develops diabetic phenotypes such as impaired glucose tolerance. The combination of diabetogenic genes in the SM/J and A/J genomes impairs glucose tolerance in SMXA-5 mice. Using (SM/J × SMXA-5)F2 mice fed a high-fat diet, we previously detected a diabetogenic locus, T2dm2sa, on chromosome (Chr) 2. The A/J allele at this locus is diabetogenic. The SM.A- T2dm2sa congenic mouse, in which the Chr 2 region of A/J including T2dm2sa was introgressed into SM/J, showed obviously impaired glucose tolerance. These results indicate that SM.A- T2dm2sa mice develop diabetogenic traits due to T2dm2sa with the A/J allele and unknown diabetogenic loci with the SM/J allele. The aim of this study was to dissect these unknown loci, using quantitative trait locus (QTL) analysis in the (A/J × SM.A- T2dm2sa) F2 intercross fed a high-fat diet. The results revealed a highly significant QTL, T2dm4sa, for glucose tolerance on Chr 6 and a significant QTL, T2dm5sa, for glucose tolerance on Chr 11. These loci with the SM/J allele were diabetogenic. The diabetogenic effect of T2dm4sa or T2dm5sa was verified by the impairment of glucose tolerance in the A/J-6SMor A/J-11SMconsomic strain, in which Chr 6 or Chr 11 of SM/J is introgressed into A/J, respectively. These results demonstrate that diabetogenic loci exist in the genomes of nondiabetic A/J and SM/J mice and suggest that T2dm2sa with the A/J allele and T2dm4sa and/or T2dm5sa with the SM/J allele elicit impaired glucose tolerance in SM.A- T2dm2sa mice.
Global expression profiling identifies a novel biosignature for protein aggregation R120GCryAB cardiomyopathy in mice
Authors: Rajasekaran Namakkal S. , Firpo Matthew A. , Milash Brett A. , Weiss Robert B. , Benjamin Ivor J.
Published: July 2008

Protein aggregation cardiomyopathy is a life-threatening manifestation of a multisystem disorder caused by the exchange mutation in the gene encoding the human small heat shock protein αB-crystallin (hR120GCryAB). Genetic studies in mice have established cardiac hR120GCryAB expression causes increased activity of glucose 6-phosphate dehydrogenase (G6PD) and “reductive stress” (Rajasekaran et al., Cell 130: 427–439, 2007). However, the initiating molecular events in the pathogenesis of this novel toxic gain-of-function mechanism remain poorly defined. In an integrated systems approach using gene expression profiling, we identified a “biosignature,” whose features can be validated to predict the onset, rate of progression, and clinical outcome of R120GCryAB cardiomyopathy. At the 3 mo disease-related but compensated stage, we demonstrate that transcripts were only upregulated in three distinct pathways: stress response (e.g., Hsp70, Hsp90), glutathione metabolism (Gpx1, Gpx3, glutathione S-transferase), and complement and coagulation cascades in hR120GCryAB transgenic mouse hearts compared with either hCryAB WT transgenic mice or nontransgenic controls. In 6 mo old myopathic hearts, ribosomal synthesis and cellular remodeling associated with increased cardiac hypertrophy were additional upregulated pathways. In contrast, the predominant downregulated pathways were for oxidative phosphorylation, fatty acid metabolism, intermediate metabolism, and energetic balance, supporting their primary pathogenic roles by which G6PD-dependent reductive stress causes cardiac decompensation and overt heart failure in hR120GCryAB cardiomyopathy. This study extends and confirms our previous findings that reductive stress is a causal mechanism for hR120G CryAB cardiomyopathy and demonstrates that alteration in glutathione pathway gene expression is an early biosignature with utility for presymptomatic detection.
Muscle weakness correlates with muscle atrophy and precedes the development of inclusion body or rimmed vacuoles in the mouse model of DMRV/hIBM
Authors: Malicdan May Christine V. , Noguchi Satoru , Hayashi Yukiko K. , Nishino Ichizo
Published: July 2008

Distal myopathy with rimmed vacuoles (DMRV), also called hereditary inclusion body myopathy (hIBM), is characterized clinically by weakness and atrophy that initially involves the distal muscles and pathologically by the presence of rimmed vacuoles (RVs) or intracellular protein deposits in myofibers. It is caused by mutations in the UDP- N-acetylglucosamine 2-epimerase/ N-acetylmannosamine kinase ( GNE) gene that is important in sialic acid synthesis. Recently, we generated a mouse model ( Gne−/−h GNED176VTg) that exhibits muscle weakness and pathological changes similar to DMRV patients. To gain better understanding of the pathomechanism of DMRV, we determined temporal changes in the overall motor performance of this model mouse for DMRV in correlation with the structure and function of isolated skeletal muscles and muscle pathology. These DMRV mice exhibited muscle weakness, decreased whole muscle mass and cross-sectional area (CSA), and reduced contractile power in an age-related manner. Single-fiber CSA further supported the finding of muscle atrophy that involved both type I and type II fibers. These results suggest that atrophy is highly correlated with reduced production of force at young age, both in vivo and ex vivo, thereby implicating the important role of atrophy in the pathomechanism of DMRV. In older age, and particularly in gastrocnemius muscles, RVs and intracellular inclusions were seen in type IIA fibers, further aggravating reduction of force and specific increase in twitch-tetanus ratio.
Identification of Stochastic Loads Applied to a Nonlinear Dynamical System Using an Uncertain Computational Model
Authors: Soize C. , Batou A.
Published: July 2008

This paper deals with the identification of stochastic loads applied to a nonlinear dynamical system for which a few experimental
responses are available using an uncertain computational model.
Uncertainties are induced by the use of a simplified computational
model to predict the responses of the real system. A nonparametric
probabilistic approach of both parameter uncertainties and model uncertainties
is implemented in the simplified computational model in
order to take into account uncertainties. The level of uncertainties is identified using the maximum likelihood method. The identified
stochastic simplified computational model which is obtained is then
used to perform the identification of the stochastic loads applied to
the real nonlinear dynamical system. A numerical validation of the
complete methodology is presented.
Open Partial Nephrectomy in the Management of Small Renal Masses
Authors: Kirkali Ziya , Canda A. Erdem
Published: July 2008

Introduction. Most of the kidney masses are being detected incidentally with smaller size due to widespread use of imaging modalities leading to increased RCC incidence worldwide with an earlier stage. This article reviews the role of open partial nephrectomy (PN) in the management of small renal masses.Material and Methods. Review of the English literature using MEDLINE has been performed between 1963–2008 on small renal masses, partial nephrectomy, kidney cancer, nephron sparing surgery (NSS), radical nephrectomy, laparoscopy, and surgical management. Special emphasis was given on the indications of NSS, oncological outcomes and comparison with open and laparoscopic PN.Results. Overall 68 articles including 31 review papers, 35 human clinical papers, 1 book chapter, and 1 animal research study were selected for the purpose of this article and were reviewed by the authors.Conclusions. Currently, open NSS still remains as the gold standard surgical treatment modality in patients with small renal masses.
Biomimetic Composite-Metal Hip Resurfacing Implant
Authors: Bougherara Habiba , Bureau Martin N.
Published: July 2008

Hip resurfacing technique is a conservative arthroplasty used in the young patient in which the femoral head is reshaped to accept metal cap with small guide stem. In the present investigation, a hybrid composite-metal resurfacing implant is proposed. The cup is made of carbon fiber/polyamide 12 (CF/PA12) covered with a thin layer of cobalt chrome (Co-Cr). Finite element (FE) method was applied to analyze and compare the biomechanical performances of the hybrid hip resurfacing (HHR) and the conventional Birmingham (BHR). Results of the finite element analysis showed that the composite implant leads to an increase in stresses in the cancellous bone by more than 15% than BHR, indicating a lower potential for stress shielding and bone fracture and higher potential for bone apposition with the HHR.
Multifocal Renal Cell Carcinoma: Clinicopathologic Features and Outcomes for Tumors≤4 cm
Authors: Crispen Paul L. , Lohse Christine M. , Blute Michael L.
Published: July 2008

A significant increase in the incidental detection of small renal tumors has been observed with the routine use of cross-sectional abdominal imaging. However, the proportion of small renal tumors associated with multifocal RCC has yet to be established. Here then, we report our experience with the treatment of multifocal RCC in which the primary tumor was ≤4 cm. In our series of 1113 RCC patients, 5.4% (60/1113) had multifocal disease at the time of nephrectomy. Discordant histology was present in 17% (10/60) of patients with multifocal RCC. Nephron sparing surgery was utilized more frequently in patients with solitary tumors. Overall, cancer-specific, and distant metastasis-free survival appeared to be similar between multifocal and solitary tumors. These findings are consistent with previous series which evaluated multifocal RCC with tumors >4 cm. With the known incidence of multifocality RCC, careful inspection of the entire renal unit should be performed when performing nephron sparing surgery.
FPGA-Based Embedded Motion Estimation Sensor
Authors: Wei Zhaoyi , Lee Dah-Jye , Nelson Brent E. , Archibald James K. , Edwards Barrett B.
Published: July 2008

Accurate real-time motion estimation is very critical to many computer vision tasks. However, because of its computational power and processing speed requirements, it is rarely used for real-time applications, especially for micro unmanned vehicles. In our previous work, a FPGA system was built to process optical flow vectors of 64 frames of640×480image per second. Compared to software-based algorithms, this system achieved much higher frame rate but marginal accuracy. In this paper, a more accurate optical flow algorithm is proposed. Temporal smoothing is incorporated in the hardware structure which significantly improves the algorithm accuracy. To accommodate temporal smoothing, the hardware structure is composed of two parts: the derivative (DER) module produces intermediate results and the optical flow computation (OFC) module calculates the final optical flow vectors. Software running on a built-in processor on the FPGA chip is used in the design to direct the data flow and manage hardware components. This new design has been implemented on a compact, low power, high performance hardware platform for micro UV applications. It is able to process 15 frames of640×480image per second and with much improved accuracy. Higher frame rate can be achieved with further optimization and additional memory space.
Generalized Cumulative Residual Entropy for Distributions with Unrestricted Supports
Authors: Drissi Noomane , Chonavel Thierry , Boucher Jean Marc
Published: July 2008

We consider the cumulative residual entropy (CRE) a recently introduced
measure of entropy. While in previous works distributions with positive support
are considered, we generalize the definition of CRE to the case of distributions
with general support. We show that several interesting properties
of the earlier CRE remain valid and supply further properties and insight to
problems such as maximum CRE power moment problems. In addition, we
show that this generalized CRE can be used as an alternative to differential
entropy to derive information‐based optimization criteria for system identification
purpose.
Tissue-Specific Promoters Active in CD44+CD24−/low Breast Cancer Cells
Authors: Bauerschmitz Gerd J. , Ranki Tuuli , Kangasniemi Lotta , Ribacka Camilla , Eriksson Minna , Porten Marius , Herrmann Isabell , Ristimäki Ari , Virkkunen Pekka , Tarkkanen Maija , Hakkarainen Tanja , Kanerva Anna , Rein Daniel , Pesonen Sari , Hemminki Akseli
Published: July 2008

It has been proposed that human tumors contain stem cells that have a central role in tumor initiation and posttreatment relapse. Putative breast cancer stem cells may reside in the CD44+CD24−/low population. Oncolytic adenoviruses are attractive for killing of these cells because they enter through infection and are therefore not susceptible to active and passive mechanisms that render stem cells resistant to many drugs. Although adenoviruses have been quite safe in cancer trials, preclinical work suggests that toxicity may eventually be possible with more active agents. Therefore, restriction of virus replication to target tissues with tissues-specific promoters is appealing for improving safety and can be achieved without loss of efficacy. We extracted CD44+CD24−/low cells from pleural effusions of breast cancer patients and found that modification of adenovirus type 5 tropism with the serotype 3 knob increased gene delivery to CD44+CD24−/low cells. α-Lactalbumin, cyclo-oxygenase 2, telomerase, and multidrug resistance protein promoters were studied for activity in CD44+CD24−/low cells, and a panel of oncolytic viruses was subsequently constructed. Each virus featured 5/3 chimerism of the fiber and a promoter controlling expression of E1A, which was also deleted in the Rb binding domain for additional tumor selectivity. Cell killing assays identified Ad5/3-cox2L-d24 and Ad5/3-mdr-d24 as the most active agents, and these viruses were able to completely eradicate CD44+CD24−/low cells in vitro. In vivo, these viruses had significant antitumor activity in CD44+CD24−/low–derived tumors. These findings may have relevance for elimination of cancer stem cells in humans. [Cancer Res 2008;68(14):5533–9]
Targeted Deletion of Rad9 in Mouse Skin Keratinocytes Enhances Genotoxin-Induced Tumor Development
Authors: Hu Zhishang , Liu Yuheng , Zhang Chunbo , Zhao Yun , He Wei , Han Lu , Yang Leilei , Hopkins Kevin M. , Yang Xiao , Lieberman Howard B. , Hang Haiying
Published: July 2008

The Rad9 gene is evolutionarily conserved from yeast to humans and plays crucial roles in genomic maintenance, DNA repair, and cell cycle checkpoint controls. However, the function of this gene with respect to tumorigenesis is not well-understood. A Rad9-null mutation in mice causes embryonic lethality. In this study, we created mice in which mouse Rad9, Mrad9, was deleted only in keratinocytes to permit examination of the potential function of the gene in tumor development. Mice with Mrad9+/− or Mrad9−/− keratinocytes showed no overt, spontaneous morphologic defects and seemed similar to wild-type controls. Painting the carcinogen 7,12-dimethylbenzanthracene (DMBA) onto the skin of the animals caused earlier onset and more frequent formation of tumors and senile skin plaques in Mrad9−/− mice, compared with Mrad9+/− and Mrad9+/+ littermates. DNA damage response genes p21, p53, and Mrad9B were expressed at higher levels in Mrad9−/− relative to Mrad9+/+ skin. Keratinocytes isolated from Mrad9−/− skin had more spontaneous and DMBA-induced DNA double strand breaks than Mrad9+/+ keratinocytes, and the levels were reduced by incubation with the antioxidant epigallocatechin gallate. These data suggest that Mrad9 plays an important role in maintaining genomic stability and preventing tumor development in keratinocytes. [Cancer Res 2008;68(14):5552–61]