bluuebunny/crossref_metadata_2025 huggingface dataset:
Transition in a Separation Bubble
Authors: Malkiel E. , Mayle R. E.
Published: April 2010

In the interest of being able to predict separating–reattaching flows, it is necessary to have an accurate model of transition in separation bubbles. An experimental investigation of the process of turbulence development in a separation bubble shows that transition occurs within the separated shear layer. A comparison of simultaneous velocity traces from comparison of simultaneous velocity traces from probes separated in the lateral direction suggests that Kelvin–Helmholtz waves, which originate in the laminar shear layer, do not break down to turbulence simultaneously across their span when they proceed to agglomerate. The streamwise development of intermittency in this region can be characterized by turbulent spot theory with a high dimensionless spot production rate. Moreover, the progression of intermittency along the centerline of the shear layer is similar to that in attached boundary layer transition. The transverse development of intermittency is also remarkably similar to that in attached boundary layers. The parameters obtained from these measurements agree with correlations previously deduced from turbulence intensity measurements.
An Investigation of the Effect of Cascade Area Ratios on Transonic Compressor Performance
Authors: Wadia A. R. , Copenhaver W. W.
Published: April 2010

Transonic compressor rotor performance is highly sensitive to variations in cascade area ratios. This paper reports on the design, experimental evaluation, and three-dimensional viscous analysis of four low-aspect-ratio transonic rotors that demonstrate the effects of cascade throat area, internal contraction, and trailing edge effective camber on compressor performance. The cascade throat area study revealed that tight throat margins result in increased high-speed efficiency with lower part-speed performance. Stall line was also improved slightly over a wide range of speeds with a lower throat-to-upstream capture area ratio. Higher internal contraction, expressed as throat-to-mouth area ratio, also results in increased design point peak efficiency, but again costs performance at the lower speeds. Reducing the trailing edge effective camber, expressed as throat-to-exit area ratio, results in an improvement in peak efficiency level without significantly lowering the stall line. Among all four rotors, the best high-speed efficiency was obtained by the rotor with a tight throat margin and highest internal contraction, but its efficiency was the lowest at part speed. The best compromise between high-speed and part-speed efficiency was achieved by the rotor with a large throat and a lower trailing edge effective camber. The difference in the shock structure and the shock boundary layer interaction of the four blade was analyzed using a three-dimensional viscous code. The analytical results are used to supplement the data and provide further insight into the detailed physics of the flow field.
Experimental and Numerical Investigation of Stator Exit Flow Field of an Automotive Torque Converter
Authors: Marathe B. V. , Lakshminarayana B. , Dong Y.
Published: April 2010

The objective of this investigation is to understand the nature of the complex flow field inside each element of the torque converter through a systematic experimental and numerical investigation of the flow field. A miniature five-hole probe was used to acquire the data at the exit of the stator at several operating conditions. The flow field is found to be highly three dimensional with substantial flow deviations, and secondary flow at the exit of the stator. The secondary flow structure, caused by the upstream radial variation of the through flow, induces flow overturning near the core. Flow separation near the shell causes flow underturning in this region. The rate of decay of stator wake is found to be slower than that observed in the wakes of axial flow turbine nozzles. The flow predictions by a Navier–Stokes code are in good agreement with the pressure and the flow field measured at the exit of the stator at the design and the off-design conditions.
Characterization of Gas Diffusion Electrodes for Polymer Electrolyte Fuel Cells
Authors: Pozio A. , Cemmi A. , Carewska M. , Paoletti C. , Zaza F.
Published: April 2010

Gas diffusion electrodes (GDEs), applied in polymer electrolyte fuel cells, are composed of a multilayer structure containing porous carbon materials and noble metal catalyst. Gas diffusion layer (GDL), a GDE component, consists of a thin layer of carbon black mixed with an organic binder, frequently polytetrafluoroethylene, which is coated onto a sheet of macroporous carbon backing cloth or paper. GDL serves as a current collector that allows ready access of fuel and oxidant to the anode and the cathode catalyst surfaces, respectively. In this work, a complete GDL state-of-the-art is first presented. Then, the effects of different fabrication methods and composition of gas diffusion layer are investigated and discussed in the light of gas permeability, thermal analysis, morphology, and electrical resistance. Besides, performances in H2/air fed cell at 50°C in different humidity conditions were discussed, and a comparison with own products and commercial GDLs was carried out. It was found that the different preparation methods influence the GDL properties, allowing the most suitable choice depending on the cell humidity conditions.
Multivariable Robust Control of a Simulated Hybrid Solid Oxide Fuel Cell Gas Turbine Plant
Authors: Tsai Alex , Banta Larry , Tucker David , Gemmen Randall
Published: April 2010

This paper presents a systematic approach to the multivariable robust control of a hybrid fuel cell gas turbine plant. The hybrid configuration under investigation comprises a physical simulation of a 300 kW fuel cell coupled to a 120 kW auxiliary power unit single spool gas turbine. The facility provides for the testing and simulation of different fuel cell models that in turn help identify the key issues encountered in the transient operation of such systems. An empirical model of the facility consisting of a simulated fuel cell cathode volume and balance of plant components is derived via frequency response data. Through the modulation of various airflow bypass valves within the hybrid configuration, Bode plots are used to derive key input/output interactions in transfer function format. A multivariate system is then built from individual transfer functions, creating a matrix that serves as the nominal plant in an H-infinity robust control algorithm. The controller’s main objective is to track and maintain hybrid operational constraints in the fuel cell’s cathode airflow and the turbo machinery states of temperature and speed under transient disturbances. This algorithm is then tested on a SIMULINK/MATLAB platform for various perturbations of load and fuel cell heat effluence.
A Combined Finite Element-Upwind Finite Volume Method for Liquid-Feed Direct Methanol Fuel Cell Simulations
Authors: Sun Pengtao , Wang Chaoyang , Xu Jinchao
Published: April 2010

In this paper, a three-dimensional, two-phase transport model of liquid-feed direct methanol fuel cell (DMFC), which is based on the multiphase mixture formulation and encompasses all components in a DMFC using a single computational domain, is specifically studied and simulated by a combined finite element-upwind finite volume discretization along with Newton’s method, where flow, species, charge-transport, and energy equations are simultaneously addressed. Numerical simulations in three dimensions are carried out to explore and design efficient and robust numerical algorithms for the sake of fast and convergent nonlinear iteration. A series of efficient numerical algorithms and discretizations is specifically designed and analyzed to assist in achieving this goal. Our numerical simulations demonstrate that the convergent and correct physical solutions can be attained within 100 more steps, against the oscillating and long-running nonlinear iterations (up to 5000 steps) performed by standard finite element/volume method without new numerical techniques.
Constant Fuel Utilization Operation of a SOFC System: An Efficiency Viewpoint
Authors: Vijay P. , Samantaray A. K. , Mukherjee A.
Published: April 2010

The operating conditions of a solid oxide fuel cell (SOFC) system that result in maximum efficiency needs to be studied by considering the whole closed circuit system because operating at maximum cell efficiency may not lead to maximum system efficiency. In this paper, this study is performed with the aid of a comprehensive steady state model of the SOFC, the after-burner, and the heat exchangers. In order to account for the large irreversibilities, the SOFC model is derived by the application of the second law of thermodynamics to the fuel cell control volumes. The SOFC system efficiency is maximized by employing a recursive algorithm with two cascaded optimization loops, which also gives the corresponding cell operating conditions. Complex control laws are required for controlling the SOFC system for maximum efficiency. On the other hand, it is found that an appropriately chosen constant fuel utilization operation closely approximates the maximum efficiency operation of the fuel cell in its operating range.
Increased Cathodic Kinetics on Platinum in IT-SOFCs by Inserting Highly Ionic-Conducting Nanocrystalline Materials
Authors: Huang Hong , Holme Tim , Prinz Fritz B.
Published: April 2010

One of the crucial factors for improving intermediate-temperature solid oxide fuel cell (SOFC) performance relies on the reduction in the activation loss originating from limited electrode reaction kinetics. We investigated the properties and functions of the nanocrystalline interlayer via quantum simulation and electrochemical impedance analyses. Electrode impedances were found to decrease several folds as a result of introducing a nanocrystalline interlayer and this positive impact was the most significant when the interlayer was a highly ionic-conducting nanocrystalline material. Both exchange current density and maximum power density were highest in the ultrathin SOFCs (fabricated with microelectromechanical systems (MEMS) compatible technologies) consisting of a 50 nm thick nano-gadolinia doped ceria (GDC) interlayer. Oxygen vacancy formation energies both at the surface and in the bulk of pure zirconia, ceria, yttria-stabilized zirconia, and GDC were computed from density functional theory, which provided insight on surface oxygen vacancy densities.
Vector Evaluated Particle Swarm Optimization (VEPSO) of Supersonic Ejector for Hydrogen Fuel Cells
Authors: M V Srisha Rao , Jagadeesh G.
Published: April 2010

Fuel cells are emerging as alternate green power producers for both large power production and for use in automobiles. Hydrogen is seen as the best option as a fuel; however, hydrogen fuel cells require recirculation of unspent hydrogen. A supersonic ejector is an apt device for recirculation in the operating regimes of a hydrogen fuel cell. Optimal ejectors have to be designed to achieve best performances. The use of the vector evaluated particle swarm optimization technique to optimize supersonic ejectors with a focus on its application for hydrogen recirculation in fuel cells is presented here. Two parameters, compression ratio and efficiency, have been identified as the objective functions to be optimized. Their relation to operating and design parameters of ejector is obtained by control volume based analysis using a constant area mixing approximation. The independent parameters considered are the area ratio and the exit Mach number of the nozzle. The optimization is carried out at a particular entrainment ratio and results in a set of nondominated solutions, the Pareto front. A set of such curves can be used for choosing the optimal design parameters of the ejector.
Evaluation of the Performance Characteristics and Modeling of an Alkaline Fuel Cell
Authors: Mohan Sujith , Bade Shrestha S. O.
Published: April 2010

Alkaline fuel cells are one of the low cost types of fuel cells. In this contribution, the performance of an alkaline fuel cell was investigated by varying different operational parameters. The cell was tested under four different electrolyte concentrations and three different levels of anode flow rates. The results of the test revealed that the efficiency of the cell increases with the increase in electrolyte concentration. Anode flow rate was not found to have a considerable impact on the cell performance. Impedance spectroscopy has been conducted to validate the mathematical model and further investigate ohmic resistance, anode and cathode activation losses, and mass transport losses. The optimal level of electrolyte concentration and anode flow rate for an alkaline fuel cell has been deduced through modeling and statistical analysis.
A new whitefish from the early Quaternary of Bluefish Basin, Yukon Territory, Canada, and its paleoenvironmental implications
Authors: Cumbaa Stephen , Lauriol Bernard , Alfonso Noel , Ross Martin , Mott Robert
Published: April 2010

A nearly complete fossil of a whitefish, Coregonus beringiaensis sp. nov. (Salmoniformes: Salmonidae: Coregoninae), the oldest known record of the genus, is described from Ch’ijee’s Bluff along the Porcupine River, Bluefish Basin, Yukon Territory. The new species is closest to but distinct from species within the Coregonus clupeaformis complex, especially in its low lateral line scale count, quadrate with an extensive canal and pore complex, Y-shaped lachrymal, and a unique combination of counts and measurements of fins, scales, and body proportions. The stratigraphic position of the source concretionary layer, at the base of unit 3, a lacustrine unit, is well below a magnetically reversed interval thought to represent at least the upper part of the Matuyama Chron. The specimen was found above ice-wedge pseudomorphs thought to be the first sign of the onset of cold temperatures in the early Quaternary. The fossil is older than 0.79 Ma and probably younger than 2.58 Ma. Palynomorphs in the concretion suggest an open shrub-tundra environment and a climate colder than that of the present, similar to conditions prevailing at or above the tree line, and a good fit for preglacial conditions in the early Quaternary. Sedimentary and geochemical analyses suggest that fossilization occurred in an environment characterized by fine sedimentation in a cold, reducing milieu with a pH of ∼7.5. Alternatively, these conditions may reflect the postdepositional or early diagenetic environment. The lake in which the whitefish lived was possibly part of a hydrographic basin draining toward the Arctic Ocean.
Evaluating behaviors of factors affecting the site index estimate on the basis of a single stand using simulation approach
Authors: Ni Chengcai , Liu Chunmei
Published: April 2010

Height observations H1and H2present on the right- and left-hand sides of site index models, respectively. The error terms associated with H1and H2, along with parameter estimate errors, affect the estimate of the site index. Projection error variance (PEV), in a projection from A1to A2, consisted of four components associated with H1, H2, the covariance of H1and H2, and the parameter estimate errors. In this study, behaviors of these components were investigated via simulations on the basis of six equations derived from the Lundqvist–Kerf and the Hossfeld IV functions. Simulation results showed that projection interval, projection direction, and selected site-dependent parameter influenced PEV and its components. PEVs of backward and forward projections with the same projection interval lengths were remarkably different if the underlying model was anamorphic. With increasing projection interval length, the PEV of forward projections monotonically increased to a certain value, whereas the PEV of backward projections decreased to zero after reaching a maximum.
Altering successional trends in oak forests: 19 year experimental results of low- and moderate-intensity silvicultural treatments
Authors: Povak Nicholas A. , Lorimer Craig G. , Guries Raymond P.
Published: April 2010

Intensive silvicultural treatments can sometimes prevent the conversion of an oak (Quercus spp.) forest to a forest composed of mesophytic competitors following harvest, but the required labor is a disincentive for many private landowners. In this study, shelterwood removal, commercial clear-cutting, understory control, and oak underplanting were conducted on mesic and dry–mesic sites in southwestern Wisconsin to evaluate the effect of these treatments on forest composition and to identify the least intensive combination needed for successful oak regeneration. Commercial clear-cutting, with or without prior herbicide spray of low vegetation and oak underplanting, resulted in nearly complete dominance by a wide array of non-oak species on both mesic and dry–mesic sites. In contrast, 153–903 ha–1of the oaks that were underplanted on shelterwood – understory removal plots successfully achieved dominant or codominant status by age 19. Control of tall understory saplings was essential for successful oak regeneration on both sites. On the mesic site, oak underplanting was an additional necessary treatment, whereas natural regeneration was adequate in shelterwood plots on the dry–mesic site. The study suggests that successful oak regeneration can be obtained on productive sites in this region after a single application of a moderately intense silvicultural treatment, although the effort required for understory control may still be an obstacle to widespread application without external incentives.
Influences of vegetation structure and elevation on CO2 uptake in a mature jack pine forest in Saskatchewan, Canada
Authors: Chasmer L. , Kljun N. , Barr A. , Black A. , Hopkinson C. , McCaughey H. , Treitz P.
Published: April 2010

Carbon dioxide, water vapour, and energy fluxes vary spatially and temporally within forested environments. However, it is not clear to what extent they vary as a result of variability in the spatial distribution of biomass and elevation. The following study presents a new methodology for extracting changes in the structural characteristics of vegetation and elevation within footprint areas, for direct comparison with eddy covariance (EC) CO2 flux concentrations. The purpose was to determine whether within-site canopy structure and local elevation influenced CO2 fluxes in a mature jack pine ( Pinus banksiana Lamb.) forest located in Saskatchewan, Canada. Airborne light detection and ranging (lidar) was used to extract tree height, canopy depth, foliage cover, and elevation within 30 min flux footprints. Within-footprint mean structural components and elevation were related to 30 min mean net ecosystem productivity (NEP) and gross ecosystem production (GEP). NEP and GEP were modeled using multiple regression, and when compared with measured fluxes, almost all periods showed improvements in the prediction of flux concentration when canopy structure and elevation were included. Increased biomass was related to increased NEP and GEP in June and August when the ecosystem was not limited by soil moisture. On a daily basis, fractional cover and elevation had varying but significant influences on CO2 fluxes.
Area-based lidar-assisted estimation of forest standing volume
Authors: Corona Piermaria , Fattorini Lorenzo
Published: April 2010

Airborne laser scanning (lidar) technology is increasingly being applied in forest ecosystem surveys. This research note proposes a design-based approach for the lidar-assisted estimation of forest standing volume when ground surveys are performed by means of fixed-area plots. The lidar measurement of the height of the upper canopy (digital crown model) is performed for the whole study area, and the resulting pixel heights are adopted as auxiliary information to couple with the standing volume acquired on the ground by means of sample plots. The ratio estimator for the total volume of the forest is derived in a complete design-based framework together with an unbiased estimator of its sampling variance and the corresponding confidence interval. The proposed procedure has been tested in Bosco della Fontana, a lowland forest in Northern Italy, obtaining a 95% confidence interval for the total volume, which is approximately 2/3 smaller than that obtained by solely using information arising from field plots.
Clonal structure and diversity of Cryptomeria japonica along a slope in a cool-temperate, old-growth mixed forest in the snowy region of Japan
Authors: Hirayama Kimiko , Sakimoto Michinori
Published: April 2010

To clarify patterns of clonal growth along a slope for Cryptomeria japonica (L.f.) D. Don, which can regenerate by layering resulting from snow pressure, we analyzed the spatial genetic structure with respect to slope position and in relation to stem size in a cool-temperate, old-growth mixed forest in the snowy region of Japan. For the genetic analysis, five polymorphic microsatellite markers developed for C. japonica were used. Spatial autocorrelation analyses revealed a significant positive association of ramets (trees) with the same genotype as the result of clonal growth at around <6 m regardless of slope position for understory trees (≥50 cm stem length and <10 cm diameter at breast height (DBH)). This clonal patch size almost corresponded to the clustering scale for overstory trees (≥10 cm DBH) belonging to the same genet. For understory trees in three subplots established along a slope, the size distribution of ramets within a clone (genet) followed an inverse J-shaped distribution without small ramets being distributed peripherally. These results suggest that each clone of C. japonica is maintained continuously in a relatively restricted area where it establishes, regardless of slope position, which could contribute to the high clonal and genetic diversity of C. japonica in this forest.
ON THE EXISTENCE OF MAXIMAL SUBRINGS IN COMMUTATIVE ARTINIAN RINGS
Authors: AZARANG A. , KARAMZADEH O. A. S.
Published: April 2010

We determine entirely which Artinian rings have maximal subring. In particular, we show that an Artinian ring without maximal subring is integral over some finite subring and in particular that every Artinian ring which is uncountable or of characteristic zero has a maximal subring. We also determine when a finite direct product of rings has a maximal subring. Finally, we show that if a ring R has an Artinian maximal subring then R itself is Artinian.
PERIODIC SHORT EXACT SEQUENCES AND PERIODIC PURE-EXACT SEQUENCES
Authors: BOUCHIBA SAMIR , KHALOUI MOSTAFA
Published: April 2010

Benson and Goodearl [Periodic flat modules, and flat modules for finite groups, Pacific J. Math.196(1) (2000) 45–67] proved that if M is a flat module over a ring R such that there exists an exact sequence of R-modules 0 → M → P → M → 0 with P a projective module, then M is projective. The main purpose of this paper is to generalize this theorem to any exact sequence of the form 0 → M → G → M → 0, where G is an arbitrary module over R. Moreover, we seek counterpart entities in the Gorenstein homological algebra of pure projective and pure injective modules.
DERIVATIONS HAVING THE SAME POWER VALUES
Authors: XU XIAO-WEI , MA JING , NIU FENG-WEN
Published: April 2010

Let R be a prime ring with extended centroid C, a nonzero ideal I and two derivations d1, d2. Suppose that d1(x)n = d2(x)n for all x ∈ I. Then there exists λ ∈ C such that d2(x) = λd1(x) for all x ∈ R.
A NEW CHARACTERIZATION OF HALF-FACTORIAL KRULL MONOIDS
Authors: BAGINSKI PAUL , KRAVITZ ROSS
Published: April 2010

Let M be a Krull monoid. Then every element of M may be written as a finite product of irreducible elements. If for every a ∈ M, each two factorizations of a have the same number of irreducible elements, then M is called half-factorial. Using a property of element exponentiation, we provide a new characterization of half-factoriality, valid for all Krull monoids whose class group has torsion-free rank at most one.
HYPERBOLICITY OF SEMIGROUP ALGEBRAS II
Authors: IWAKI E. , JESPERS E. , JURIAANS S. O. , SOUZA FILHO A. C.
Published: April 2010

In 1996, Jespers and Wang classified finite semigroups whose integral semigroup ring has finitely many units. In a recent paper, Iwaki–Juriaans–Souza Filho continued this line of research by partially classifying the finite semigroups whose rational semigroup algebra contains a ℤ-order with hyperbolic unit group. In this paper, we complete this classification and give an easy proof that deals with all finite semigroups.
THE NUMERICAL MANIFOLD METHOD: A REVIEW
Authors: MA GUOWEI , AN XINMEI , HE LEI
Published: April 2010

This paper presents a review on the numerical manifold method (NMM), which covers the basic theories of the NMM, such as NMM components, NMM displacement approximation, formulations of the discrete system of equations, integration scheme, imposition of the boundary conditions, treatment of contact problems involved in the NMM, and also the recent developments and applications of the NMM. Modeling the strong discontinuities within the framework of the NMM is specially emphasized. Several examples demonstrating the capability of the NMM in modeling discrete block system, strong discontinuities, as well as weak discontinuities are given. The similarities and distinctions of the NMM with various other numerical methods such as the finite element method (FEM), the extended finite element method (XFEM), the generalized finite element method (GFEM), the discontinuous deformation analysis (DDA), and the distinct element method (DEM) are investigated. Further developments on the NMM are suggested.
EULERIAN FINITE COVER METHOD FOR SOLID DYNAMICS
Authors: OKAZAWA SHIGENOBU , TERASAWA HIDEYUKI , KURUMATANI MAO , TERADA KENJIRO , KASHIYAMA KAZUO
Published: April 2010

In order to deal with the kinematic and dynamic boundary conditions in the Eulerian framework, we develop an Eulerian finite cover method (FCM) for large deformation solid dynamics by incorporating the approximation strategy of the FCM into the existing Eulerian explicit finite element method. The operator split method is employed to solve Eulerian solid dynamics problems, and the resulting numerical algorithm consists of two steps. One is the nonadvective step, in which the standard Lagrangian FC analysis is carried out with the explicit time integration scheme, and the other is the advective step, in which the CIVA method is applied to project the solution obtained in the nonadvective step to the Eulerian mesh. Two representative numerical examples are presented to validate the proposed Eulerian FCM and demonstrate its capability especially in appropriately treating the kinematic and dynamic boundary conditions.
DEVELOPMENT OF COUPLED DISCONTINUOUS DEFORMATION ANALYSIS AND NUMERICAL MANIFOLD METHOD (NMM–DDA)
Authors: MIKI SHIGERU , SASAKI TAKESHI , KOYAMA TOMOFUMI , NISHIYAMA SATOSHI , OHNISHI YOZO OHNISH
Published: April 2010

Discontinuous Deformation Analysis (DDA) and Numerical Manifold Method (NMM) have been widely used for the analyses of discontinuous rock masses. Recently, these discontinuum-based numerical methods have been applied to the simulations for slope failure due to earthquakes, where one of the key issues is the estimation of traveling velocities and distances for the collapsed rock blocks. For the dynamic response analysis of rock slopes, it is necessary to consider the local variation of seismic forces, especially when the slope size is large and/or the slope geometry becomes complicated. In DDA, there is difficulty to consider the local displacements and stress condition of the single block for the basement because of mathematical principle (in DDA, the displacement function is defined at the gravity center of the blocks and the strain in the block is uniform). On the other hand, NMM can simulate both continuous and discontinuous deformation of the block systems. However, the rigid body rotation of blocks cannot be treated properly because NMM does not deal with the rigid body rotation in explicit form. According to the above-mentioned features and drawbacks, it is reasonable to combine DDA and NMM from practical point of view. In this paper, the formulation for the coupled NMM and DDA (NMM–DDA) was presented. For the formulation, NMM and DDA can be easily combined by choosing displacements of the DDA blocks and NMM cover nodes as unknowns, because the processes to establish the equilibrium equations (minimizing total potential energy) and kinematics for block system are same between DDA and NMM. In this paper, some applications of the NMM–DDA to both dynamic and static problems were also presented and the validity and applicability of newly developed DDA–MM were discussed.
A NUMERICAL MANIFOLD METHOD FOR PLANE MICROPOLAR ELASTICITY
Authors: ZHAO GAO-FENG , MA GUO-WEI , ZHANG HUI-HUA , ZHAO JIAN
Published: April 2010

A numerical manifold method (NMM) for plane micropolar elasticity is proposed in this paper to consider the microstructure influence of materials. First, the basic formulations of plane micropolar elasticity are briefly introduced. Then, the equations of stiffness matrix, boundary conditions, and equivalent force in micropolar NMM are derived based on energy minimization principle. Two manifold elements for micropolar elasticity are provided later. From geometry analysis, the proposed SQ-ME model will have about 40% less degree of freedoms than the corresponding finite element method model. Patch tests are used to validate these two manifold elements and the results show these elements could pass patch tests exactly. Furthermore, the micropolar NMM is used to predict the stress concentration of a micropolar membrane containing a small hole. The results are in agreement with the micropolar analytical solution. Finally, convergence analysis is performed and conclusions are derived.
Longitudinal study of BGP monitor session failures
Authors: Cheng Pei-chun , Zhao Xin , Zhang Beichuan , Zhang Lixia
Published: April 2010

BGP routing data collected by RouteViews and RIPE RIS have become an essential asset to both the network research and operation communities. However, it has long been speculated that the BGP monitoring sessions between operational routers and the data collectors fail from time to time. Such session failures lead to missing update messages as well as duplicate updates during session re-establishment, making analysis results derived from such data inaccurate. Since there is no complete record of these monitoring session failures, data users either have to sanitize the data discretionarily with respect to their specific needs or, more commonly, assume that session failures are infrequent enough and simply ignore them. In this paper, we present the first systematic assessment and documentary on BGP session failures of RouteViews and RIPE data collectors over the past eight years. Our results show that monitoring session failures are rather frequent, more than 30% of BGP monitoring sessions experienced at least one failure every month. Furthermore, we observed failures that happen to multiple peer sessions on the same collector around the same time, suggesting that the collector's local problems are a major factor in the session instability. We also developed a web site as a community resource to publish all session failures detected for RouteViews and RIPE RIS data collectors to help users select and clean up BGP data before performing their analysis.
Bone Marrow Derivation of Interstitial Cells of Cajal in Small Intestine Following Intestinal Injury
Authors: Liu Dengqun , Wang Fengchao , Zou Zhongmin , Dong Shiwu , Wang Junping , Ran Xinze , Li Chunxue , Shi Chunmeng , Su Yongping
Published: April 2010

Interstitial cells of Cajal (ICCs) in gastrointestinal tract are specialized cells serving as pacemaker cells. The origin of ICCs is currently not fully characterized. In this work, we aimed to study whether bone marrow-derived cells (BMDCs) could contribute to the origin of ICCs in the muscular plexus of small intestine using GFP-C57BL/6 chimeric mice.Engraftment of BMDCs in the intestine was investigated for GFP expression. GFP positive bone marrow mononuclear cells reached a proportion of95.65%±3.72%at different times in chimerism. Donor-derived cells distributed widely in all the layers of the gastrointestinal tract. There were GFP positive BMDCs in the myenteric plexus, which resembled characteristics of ICCs, including myenteric location, c-Kit positive staining, and ramified morphology. Donor-derived ICCs in the myenteric plexus contributed to a percentage ranging9.25%±4.9%of all the ICCs in the myenteric plexus. In conclusion, here we described that donor-derived BMDCs might differentiate into gastrointestinal ICCs after radiation injury, which provided an alternative source for the origin of the ICCs in the muscular plexus of adult intestine. These results further identified the plasticity of BMDCs and indicated therapeutic implications of BMDCs for the gastrointestinal dysmotility caused by ICCs disorders.
Using Universal Patterns of Caries for Planning and Evaluating Dental Care
Authors: Sheiham A. , Sabbah W.
Published: April 2010

There are universal patterns of caries, in terms of prevalence, incidence, frequency distribution and rates of progression, in permanent teeth that can be considered working rules that can be applied when planning dental care. The universal patterns are: (1) caries levels follow trend lines; therefore, knowing the caries level at one age can be used to predict the levels at later ages in that cohort by looking at the trend line for that cohort; (2) the distribution of dental caries of a population exhibits the following characteristics: as the mean DMFT increases, the percentage of caries-free individuals falls and the caries distribution widens; this changing relationship between the mean DMFT and prevalence is not limited to a subgroup of the population who already have had some caries experience; (3) there is a specific mathematical relationship between the mean DMFT and mean DMFS; (4) there is a hierarchy of caries susceptibility by tooth type and sites on teeth; for a given DMFT or DMFS, there is a specific intra-oral pattern of caries by tooth type; (5) changes in mean DMFT scores for individuals and groups are not linear, but ‘stepped’; there are groupings of teeth and tooth sites that may have similar ‘resistance’ to caries; (6) as the mean DMFT declines, the posteruptive time for initiation of caries increases and the progression rate of caries through enamel decreases. This is true regardless of the presence of fluoride. Any improvement in dental health will cause this effect.
Effects of Angiotensin II on Renal Dopamine Metabolism: Synthesis, Release, Catabolism and Turnover
Authors: Choi Marcelo R. , Lee Brenda M. , Medici Cecilia , Correa Alicia H. , Fernández Belisario E.
Published: April 2010

Background/Aims: Dopamine (DA) uptake inhibition in the renal cortex, elicited by angiotensin II (ANG II), is mediated by AT1 receptors and signals through the phospholipase C pathway and activation of protein kinase C and CaM-kinase II. By this indirect way, ANG II stimulates renal Na+,K+-ATPase activity through DA intracellular reduction. In the present work, we continued to study different aspects of renal DA metabolism in DA-ANG II interaction, such as DA synthesis, release, catabolism and turnover. Methods: ANG II effects on DA synthesis, release, catabolism and turnover were measured in samples from the outer renal cortex of Sprague-Dawley rats. Results: ANG II reduced renal aromatic acid decarboxylate activity without affecting basal secretion of DA or its KCl-induced release. Moreover, ANG II enhanced monoamine oxidase activity without altering catechol-o-methyl transferase activity and increased DA turnover. Conclusion: Current results as well as previous findings show that ANG II modifies DA metabolism in rat renal cortex by reducing DA uptake, decreasing DA synthesis enzyme activity and increasing monoamine oxidase activity, and DA turnover. Together, all these effects may reduce DA accumulation into renal cells and decrease its endogenous content and availability. This would prevent D1 receptor recruitment and stimulation, while diminishing DA inhibition of Na+,K+-ATPase activity and stimulating sodium reabsorption.
Bullying in German Primary Schools
Authors: Von Marées Nandoli , Petermann Franz
Published: April 2010

The study discussed herein assessed the prevalence of bullying and analysed possible predictors for bullying in a sample of urban primary school-age children. Factors considered were students’ gender and age differences as well as parents’ educational level and migration backgrounds. Using a cross-informant approach (self- and teacher-reports), bullying was assessed among 550 children between the ages of 6.5 and 10.8 years attending 12 regular primary schools in Bremen and Lower Saxony, Germany. Overall, 10 percent of children were classified as bullies, 17.4 percent as victims and 16.5 percent as bully/victims, with boys being bullies and bully/victims more often than girls. Direct bullying was more likely directed at, and employed by, boys. Indirect/relational bullying occurred less frequently and mainly within same-gender groups. Results from logistic regression analyses showed that, apart from age and gender, low parental educational levels were a significant predictor for a child’s bullying status (bully, victim, bully/victim). Implications for bullying assessment, prevention and intervention programs are discussed.
Children’s Bullying Experiences Expressed Through Drawings and Self-Reports
Authors: Andreou Eleni , Bonoti Fotini
Published: April 2010

Traditionally, studies assessing children’s experiences of bullying and victimization have focused on the use of questionnaires and peer-nominations. The present study aimed to investigate this phenomenon by using two complementary assessment tools, namely self-reported questionnaires and children’s drawings. The sample consisted of 448 boys and girls drawn from the 4th to 6th grade classrooms of ten primary schools in Central Greece. Children were asked to: (a) draw a scene of peer victimization taking place in their school and (b) complete self-reported questionnaires regarding bullying behaviour, victimization and participant roles in bully/victim incidences. Although the results showed that the relation between drawing and self-report measures is not a straightforward one, they do reveal some interesting associations primarily related to gender differences. In other words, it was found that boys outnumbered girls in both bullying behaviour and victimization. Regarding the employed forms of victimization, boys tended to depict themselves in more physical aggression scenes than girls, while girls tended to draw themselves in more verbal victimization scenes than boys.
Justice: Rights and Wrongs. An Overview
Authors: Hordern Joshua
Published: April 2010

This is a non-evaluative overview of Justice: Rights and Wrongs covering its three parts: (i) an ‘archaeological’ account of justice and rights in the Christian tradition; (ii) a description of the goods to which we have rights; (iii) an argument grounding natural, inherent, human rights to goods in God’s love.
But to Do Right… Why the Language of ‘Rights’ Does Not Do Justice to Justice
Authors: Wannenwetsch Bernd
Published: April 2010

The essay critically engages Woltertorff’s account of justice by challenging the political status of its archaeological defence of rights language, its prioritizing of ‘primary’ and therefore ‘procedural’ justice, its suggestion to think of rights as ‘social bonds’ and the validity of subjecting God and world under one and the same concept of ‘worth’.
Two Questions for Wolterstorff: On the Roles Played by Rights-Talk in History and the Measuring of Worth
Authors: Perry John
Published: April 2010

Much of Nicholas Wolterstorff’s argument in Justice: Rights and Wrongs is persuasive and helpful, especially his focus on perceiving instances of injustice as wronging, i.e., the denial of the goods to which one has a right. Two aspects of his theory are less persuasive, one historical and one theoretical. Historically, although he convincingly shows that the concept of rights is much older than some claim, he does not account for how the function of rights-talk may have changed. Theoretically, his account of worth seems undeveloped. Worthy art or worthy philosophy papers or worthy acts of love have different rights than unworthy such objects. But how is such worth measured? It would seem that the standard of excellence appropriate to each object does at least part of the work in generating the right, thus suggesting that rights are not generated by worth alone, as Wolterstorff implies.
Rights, Happiness and God: A Response to Justice: Rights and Wrongs
Authors: Crisp Roger
Published: April 2010

This paper is a discussion of some themes from Justice: Rights and Wrongs, by Nicholas Wolterstorff. The paper begins with a discussion of Wolterstorff’s distinction between justice as inherent rights and justice as inherent worth. It is suggested that what especially distinguishes Wolterstorff’s position is his grounding of rights in divine love. An elucidation and defence of an Aristotelian eudaimonist grounding for rights is offered. The paper ends with a critique of the ideas that human well-being can be understood in terms of what God desires for us and that our worth depends on God’s love.
What Human Rights Are There—if Any—and Why?
Authors: Endicott Timothy
Published: April 2010

Are there human rights to a good such as social welfare, which depends on circumstances, and on the needs of a putative right-holder? Is justice constituted by rights? Does it take belief in God to understand the grounds of human rights? The essay responds to Nicholas Wolterstorff’s answers to these questions.
Straightforward critics or would-be candidates? International migrants and the management of local affairs and development: the case of the Senegal River valley
Authors: Sall Mohamadou
Published: April 2010

The Senegal River valley has long been one of the main sources of out-migration to international destinations in the country, and migrants’ remittances are important for the survival of households and for the economic and social development of the area. Investments in home towns and a highly critical view of the ways in which local affairs are managed encourage migrants’ active involvement in local development through associations and, increasingly, in local politics. This paper describes these processes in the light of decentralization in Senegal, and especially the transferring of competences on the use of state and public lands to local government.
Migrants as a source of revenue in small towns in China
Authors: Bingqin Li  , Xiangsheng An
Published: April 2010

This paper uses the cases of four small towns in Shanxi province, PRC, to examine how domestic migration has been used to boost the local economies and generate local revenues. However, how to govern migration is not a priority and as a result, the outcome of migration governance is very much affected by the ways in which towns interact with the higher authorities.
The Co-location of YP4 and Centrelink in Bendigo, Australia
Authors: Grace Marty , Coventry Louise
Published: April 2010

• Summary: One expression of partnership between two organizations is the sharing of office space, often known as co-location. In early 2006, case managers employed by Loddon Mallee Housing Services (LMHS), a community-based organization in the regional city of Bendigo, Australia, co-located with the Bendigo office of Centrelink, the Australian government’s statutory income support agency. This article explores Centrelink and LMHS staff and management expectations of co-location as well as the reality of co-location as experienced by the staff involved. It is based on interviews conducted with staff and managers before co-location occurred and again six months thereafter.

• Findings: Co-location is a powerful strategy for strengthening inter-agency relationships. The Bendigo example of service co-location provides confirmation of the benefits of co-location suggested in previous literature, including greater respect and trust between professionals from different backgrounds and with different status; informal information exchange, learning and sharing; enhanced feelings of teamwork and belonging; improved morale among staff; and enhanced communication, learning and understanding of roles.

• Application: This study found that key issues requiring attention by organizations contemplating co-location include building on pre-existing trust and goodwill; thorough planning, taking into account the potential impact of co-location on third parties as well as client and organizational priorities; attending to logistical details, taking particular account of timelines for connection of telephones and internet access; consulting widely and including all relevant stakeholders in decision-making processes; promoting flexible attitudes and openness to change among affected staff; and seeking to acknowledge and contain rather than remove differences in organizational culture and practice. Compatibility, rather than sameness, should be the goal.
The Berlin Wall from a visual perspective: comments on the construction of a political media icon
Authors: Drechsel Benjamin
Published: April 2010

The ‘pictorial turn’ is by now making itself felt strongly in research on political communication. This scientific trend should be linked to another key paradigmatic shift within cultural studies: to be precise, to research on phenomena of the culture of memory. The term ‘(media) icon’ could very well be useful in this context. It has already gained currency in transdisciplinary usage and is often combined with research on photographs, i.e. research on single famous images. In this article, a model of political media icons is developed that focuses on a more complex association of images. It uses the Berlin Wall as an example: this structure was a political tool of decisive importance in the so-called Cold War and has remained its key symbol to this day. The public iconization of the Berlin Wall combines architectural, cinematographic and photographic visual media with many others. Taken in its entirety, the Berlin Wall is capable of illustrating both the relevance and the many layers of pictorial phenomena in the context of political communication.
Dissecting multilingual Beijing: the space and scale of vernacular globalization
Authors: Lin Pan
Published: April 2010

Following Scollon and Scollon’s Discourse in Place: Language in the Material World (2003) in which the authors proposed that the placement and lettering of signs in public places convey the sociopolitical meaning of the region and society, this article employs the geosemiotic principles that they introduced to explore how regimes of languages are organized in fast globalizing Beijing. In doing so, the author incorporates the ‘space and scale’ perspective initiated by Immanuel Wallerstein and enriched by Blommaert, in an attempt to anchor the analysis of the phenomenology of multilingual language usage in a social and ideological context. She examines how the occurrence of standard and non-standard multilingual patterns in the streets of Beijing, a fast globalizing city, reflects people’s unequal access to global linguistic resources and marks the social stratification and power disparity that operate at various vertical scales. The article argues that the international discourse flow to China not only produces horizontal linguistic diversity but also engenders a ‘vertical scaling’ of domination and subordination, and proposes that linguistic globalization in Beijing can be viewed as a product crucially connected with social, political and ideological processes.