bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigation of Hydrodynamic Forces on Rotating and Whirling Centrifugal Pump Impellers
Authors: Fongang R. , Colding-Jo̸rgensen J. , Nordmann R.
Published: July 2011

A two-dimensional fluid model is developed to investigate the hydrodynamic forces exerted on a rotating impeller caused by the impeller-fluid-volute interaction in a centrifugal pump. In this model, the impeller periphery and the volute contour are replaced by a distribution of unsteady vortices. The impeller center is assumed to execute a whirling motion about the rotor center. This is an improvement of the earlier quasi-steady flow model of Colding-Jo̸rengsen (1980) where the impeller was taken as a single vortex source point. The forces can be presented as a sum of a steady and an unsteady part. The rotordynamic coefficients are deduced from the unsteady forces decomposed into radial and tangential components relative to the orbit described by the impeller center. In comparison to most of the theoretical and experimental results found in the literature, the model seems to give good prediction. It appears clearly from this analysis that, under certain operating conditions, the fluid forces on the impeller have a destabilizing effect on the pump rotor.
Analysis of the Flow in Vaneless Diffusers With Large Width-to-Radius Ratios
Authors: Dou H.-S. , Mizuki S.
Published: July 2011

The flow in vaneless diffusers with large width-to-radius ratios is analyzed by using three-dimensional boundary-layer theory. The variations of the wall shear angle in the layer and the separation radius of the turbulent boundary layer versus various parameters are calculated and compared with experimental data. The effect of the separation point on the performance of vaneless diffusers and the mechanism of rotating stall are discussed. It is concluded that when the flow rate becomes very low, the reverse flow zone on the diffuser walls extends toward the entry region of diffusers. When the rotating jet-wake flow with varying total pressure passes through the reverse flow region near the impeller outlet, rotating stall is generated. The influences of the radius ratio on the reverse flow occurrence as well as on the overall performance are also discussed.
Fluctuating Thermal Field in the Near-Hole Region for Film Cooling Flows
Authors: Kohli A. , Bogard D. G.
Published: July 2011

The film cooling flow field is the result of a highly complex interaction between the film cooling jets and the mainstream. Understanding this interaction is important in order to explain the physical mechanisms involved in the rapid decrease of effectiveness, which occurs close to the hole exit. Not surprisingly, it is this region that is not modeled satisfactorily with current film cooling models. This study uses a high-frequency-response temperature sensor, which provides new information about the film cooling flow in terms of actual turbulence levels and probability density functions of the thermal field. Mean and rms temperature results are presented for 35 deg round holes at a momentum flux ratio of I = 0.16, at a density ratio of DR = 1.05. Probability density functions of the temperature indicate penetration of the mainstream into the coolant core, and ejection of coolant into the mainstream. Extreme excursions in the fluctuating temperature measurements suggest existence of strong intermittent flow structures responsible for dilution and dispersion of the coolant jets.
Full Surface Local Heat Transfer Coefficient Measurements in a Model of an Integrally Cast Impingement Cooling Geometry
Authors: Gillespie D. R. H. , Wang Z. , Ireland P. T. , Kohler S. T.
Published: July 2011

Cast impingement cooling geometries offer the gas turbine designer higher structural integrity and improved convective cooling when compared to traditional impingement cooling systems, which rely on plate inserts. In this paper, it is shown that the surface that forms the jets contributes significantly to the total cooling. Local heat transfer coefficient distributions have been measured in a model of an engine wall cooling geometry using the transient heat transfer technique. The method employs temperature-sensitive liquid crystals to measure the surface temperature of large-scale perspex models during transient experiments. Full distributions of local Nusselt number on both surfaces of the impingement plate, and on the impingement target plate, are presented at engine representative Reynolds numbers. The relative effects of the impingement plate thermal boundary condition and the coolant supply temperature on the target plate heat transfer have been determined by maintaining an isothermal boundary condition at the impingement plate during the transient tests. The results are discussed in terms of the interpreted flow field.
Computational Analysis of Conjugate Heat Transfer and Particulate Deposition on a High Pressure Turbine Vane
Authors: Ai Weiguo , Fletcher Thomas H.
Published: July 2011

Numerical computations were conducted to simulate flash deposition experiments on gas turbine disk samples with internal impingement and film cooling using a computational fluid dynamics (CFD) code (FLUENT). The standard k-ω turbulence model and Reynolds-averaged Navier–Stokes were employed to compute the flow field and heat transfer. The boundary conditions were specified to be in agreement with the conditions measured in experiments performed in the BYU turbine accelerated deposition facility (TADF). A Lagrangian particle method was utilized to predict the ash particulate deposition. User-defined subroutines were linked with FLUENT to build the deposition model. The model includes particle sticking/rebounding and particle detachment, which are applied to the interaction of particles with the impinged wall surface to describe the particle behavior. Conjugate heat transfer calculations were performed to determine the temperature distribution and heat transfer coefficient in the region close to the film cooling hole and in the regions further downstream of a row of film cooling holes. Computational and experimental results were compared to understand the effect of film hole spacing, hole size, and TBC on surface heat transfer. Calculated capture efficiencies compare well with experimental results.
From the Phan–Thien–Tanner/Oldroyd-B Non-Newtonian Model to the Double Shear Thining Rabinowisch Thin Film Model
Authors: Bayada Guy , Chupin Laurent , Martin Sébastien
Published: July 2011

In this paper, an asymptotic expansion is used to derive a description of Phan–Tien– Tanner (PTT)/Oldroyd-B flows in the thin film situation without the classical “upper convective maxwell”(UCM) assumption. We begin with a short presentation of the Phan–Thien–Tanner/Oldroyd-B models, which introduce viscoelastic effects in a solute–solvent mixture. The three-dimensional flow is described using five parameters, namely the Deborah number (De) (or the relaxation parameter λ), the viscosity ratio r, the bulk fluid viscosity η, the material slip parameter a related to the “convected derivative” and an elongation number κ. Then we focus on the thin film assumption and the related asymptotic analysis that allows us to derive a reduced model. A perturbation procedure for “not too small” values of κ allows us to obtain further results such as an asymptotic “effective viscosity/ shear rate” law, which appears to be a perturbation of the double Rabinowisch model, whose parameters are completely defined by those of the original three-dimensional model. And last a numerical procedure is proposed based on a penalized Uzawa method, to compute the corresponding solution. This algorithm can also be used for any generalized double Newtonian shear thinning Carreau law.
The Inclusion of Friction in Lattice-Based Cellular Automata Modeling of Granular Flows
Authors: Marinack Martin C. , Higgs C. Fred
Published: July 2011

Granular flows continue to be a complex problem in nature and industrial sectors where solid particles exhibit solid, liquid, and gaseous behavior, in a manner which is often unpredictable locally or globally. In tribology, they have also been proposed as lubricants because of their liquid-like behavior in sliding contacts and due to their ability to carry loads and accommodate surface velocities. The present work attempts to model a granular Couette flow using a lattice-based cellular automata computational modeling approach. Cellular automata (CA) is a modeling platform for obtaining fast first-order approximations of the properties of many physical systems. The CA framework has the flexibility to employ rule-based mathematics, first-principle physics, or both to rapidly model physical processes, such as granular flows. The model developed in this work incorporates dissipative effects due to friction between particles and between particles and boundaries, in addition to the derivative effects of friction, namely particle spin. This new model also includes a rigorous and physically relevant treatment of boundary–particle interactions. The current work compares this new friction and spin inclusive CA model and the author’s previous frictionless CA model against experimental results for an annular shear cell. The effects of granular collision properties were also examined through parametric studies on particle–particle coefficient of restitution (COR) and coefficient of friction (COF), which is a unique and added capability of the friction inclusive model.
High Temperature Thermochemical Heat Storage for Concentrated Solar Power Using Gas–Solid Reactions
Authors: Schaube Franziska , Wörner Antje , Tamme Rainer
Published: July 2011

High temperature thermal storage technologies that can be easily integrated into future concentrated solar power plants are a key factor for increasing the market potential of solar power production. Storing thermal energy by reversible gas–solid reactions has the potential of achieving high storage densities while being adjustable to various plant configurations. In this paper the Ca(OH)2/CaO reaction system is investigated theoretically. It can achieve storage densities above 300 kWh/m3 while operating in a temperature range between 400 and 600°C. Reactor concepts with indirect and direct heat transfer are being evaluated. The low thermal conductivity of the fixed bed of solid reactants turned out to considerably limit the performance of a storage tank with indirect heat input through the reactor walls. A one-dimensional model for the storage reactor is established and solved with the Finite Element Method. The reactor concept with direct heat transfer by flowing the gaseous reactant plus additional inert gas through the solid reactants did not show any limitation due to heat transfer. If reaction kinetics are fast enough, the reactor performance in case of the Ca(OH)2/CaO reaction system is limited by the thermal capacity of the gaseous stream to take-up heat of reaction. However, to limit pressure drop and the according losses for compression of the gas stream, the size of the storage system is restricted in a fixed bed configuration.
Analysis of Solar-Thermal Power Plants With Thermal Energy Storage and Solar-Hybrid Operation Strategy
Authors: Giuliano Stefano , Buck Reiner , Eguiguren Santiago
Published: July 2011

Selected solar-hybrid power plants for operation in base-load as well as midload were analyzed regarding supply security (dispatchable power due to hybridization with fossil fuel) and low CO2 emissions (due to integration of thermal energy storage). The power plants were modeled with different sizes of solar fields and different storage capacities and analyzed on an annual basis. The results were compared to each other and to a conventional fossil-fired combined cycle in terms of technical, economical, and ecological figures. The results of this study show that in comparison to a conventional fossil-fired combined cycle, the potential to reduce the CO2 emissions is high for solar-thermal power plants operated in base-load, especially with large solar fields and high storage capacities. However, for dispatchable power generation and supply security it is obvious that in any case a certain amount of additional fossil fuel is required. No analyzed solar-hybrid power plant shows at the same time advantages in terms of low CO2 emissions and low levelized electricity cost (LEC). While power plants with solar-hybrid combined cycle (SHCC®, Particle-Tower) show interesting LEC, the power plants with steam turbine (Salt-Tower, Parabolic Trough, CO2-Tower) have low CO2 emissions.
Recycled Material for Sensible Heat Based Thermal Energy Storage to be Used in Concentrated Solar Thermal Power Plants
Authors: Py Xavier , Calvet Nicolas , Olives Régis , Meffre Antoine , Echegut Patrick , Bessada Catherine , Veron Emmanuel , Ory Sandra
Published: July 2011

Current technologies of concentrated solar power plants (CSP) are under extensive industrial development but still suffer from lack of adapted thermal energy storage (TES) materials and systems. In the case of extended storage (some hours), thousands of tonnes of materials are concerned leading to high investment cost, high energy and GHG contents and major conflicts of use. In this paper, recycled industrial ceramics made by vitrification of asbestos containing wastes (ACW) are studied as candidates to be used as sensible TES material. The material presents no hazard, no environmental impact, good thermophysical properties (λ= 1.4 W m−1 K−1; Cp = 1025 J kg−1 K−1; ρ= 3100 kg m−3) and at very low investment cost. Thanks to the vitrification process of the wastes, the obtained ceramics is very stable up to 1200 °C and can be directly manufactured with the desired shape. The vitrified ACW can be used as TES material for all kinds of the CSP processes (from medium up to high concentration levels) with properties in the same range than other available materials but with lower cost and without conflict of use. The proposed approach leads also to sustainable TES allowing a pay back of the energy needed for the initial waste treatment. Furthermore, this new use of the matter can enhance the waste treatment industry instead of land fill disposal.
Development of Correlations for Predicting the Slurry Erosion of Ductile Materials
Authors: Desale Girish R. , Gandhi Bhupendra K. , Jain S. C.
Published: July 2011

Material loss due to erosion is a serious problem associated with the flow of solid-liquid mixtures. In the present work, erosion wear tests have been carried out in a slurry pot tester for seven different ductile type materials namely aluminum alloy (AA6063), copper, brass, mild steel, AISI 304L stainless steel, AISI 316L stainless steel, and turbine blade grade steel using three different erodents namely, quartz, alumina, and silicon carbide. Experiments have been performed at different orientation angles of target material at the velocities of 3, 6, and 8.33 m/s for solid concentrations of 10%, 20%, and 30% (by weight) and particle sizes of 363, 550, and 655 μm. The contribution of cutting wear in the total wear of ductile material at various orientation angles has been determined. It is observed that the maximum cutting wear angle for the ductile material depends on its hardness and a correlation is developed for its prediction. Also a methodology is proposed for estimation of the total erosion wear rate as a contribution of cutting and deformation wear rates. It is seen that this procedure results in an error of ±18% in estimation of erosion wear rate for the present experimental data.
Spin‐history artifact during functional MRI: Potential for adaptive correction
Authors: Yancey Sadie E. , Rotenberg David J. , Tam Fred , Chiew Mark , Ranieri Shawn , Biswas L. , Anderson Kevan J. T. , Nicole Baker S. , Wright Graham A. , Graham Simon J.
Published: July 2011

Purpose:

Functional magnetic resonance imaging (fMRI) is limited by sensitivity to millimetre‐scale head motion. Adaptive correction is a strategy to adjust the imaging plane in response to measured head motion, thereby suppressing motion artifacts. This strategy should correct for motion in all six degrees of freedom and also holds promise for through‐plane motion that creates “spin‐history” artifact that cannot easily be removed by postprocessing methods. Improved quantitative understanding of the MRI signal behavior associated with spin‐history artifact would be useful for implementing adaptive correction robustly.

Methods:

A numerical simulation was developed to predict MRI artifact signal amplitude in a single‐slice for simple motions, implemented with and without adaptive correction, and compared with experiment by imaging a phantom at 3.0 T. Functional MRI was also performed of a human volunteer to illustrate adaptive correction in the presence of spin‐history artifact.

Results:

Good agreement was achieved between simulation and experimental results. Although time‐averaged artifact signal amplitude was observed to correlate linearly with motion speed, artifact time‐courses were nonlinearly related to motion waveforms. In addition, experimental results demonstrated effective adaptive correction of spin‐history artifact when the phantom underwent complex motions. Adaptive correction during human fMRI suppressed spin‐history artifacts and spurious activations associated with task‐correlated motion.

Conclusions:

Overall, this work suggests that adaptive correction, especially when implemented with minimal lag between motion measurement and scan plane update, may help to expand the populations for which fMRI can be performed robustly.
3D automatic anatomy segmentation based on iterative graph‐cut‐ASM
Authors: Chen Xinjian , Bagci Ulas
Published: July 2011

Purpose: This paper studies the feasibility of developing an automatic anatomy segmentation (AAS) system in clinical radiology and demonstrates its operation on clinical 3D images.Methods: The AAS system, the authors are developing consists of two main parts: object recognition and object delineation. As for recognition, a hierarchical 3D scale‐based multiobject method is used for the multiobject recognition task, which incorporates intensity weighted ball‐scale (b‐scale) information into the active shape model (ASM). For object delineation, an iterative graph‐cut‐ASM (IGCASM) algorithm is proposed, which effectively combines the rich statistical shape information embodied in ASM with the globally optimal delineation capability of the GC method. The presented IGCASM algorithm is a 3D generalization of the 2D GC‐ASM method that they proposed previously in Chen et al. [Proc. SPIE, 7259, 72590C1–72590C‐8 (2009)]. The proposed methods are tested on two datasets comprised of images obtained from 20 patients (10 male and 10 female) of clinical abdominal CT scans, and 11 foot magnetic resonance imaging (MRI) scans. The test is for four organs (liver, left and right kidneys, and spleen) segmentation, five foot bones (calcaneus, tibia, cuboid, talus, and navicular). The recognition and delineation accuracies were evaluated separately. The recognition accuracy was evaluated in terms of translation, rotation, and scale (size) error. The delineation accuracy was evaluated in terms of true and false positive volume fractions (TPVF, FPVF). The efficiency of the delineation method was also evaluated on an Intel Pentium IV PC with a 3.4 GHZ CPU machine.Results: The recognition accuracies in terms of translation, rotation, and scale error over all organs are about 8 mm, 10° and 0.03, and over all foot bones are about 3.5709 mm, 0.35° and 0.025, respectively. The accuracy of delineation over all organs for all subjects as expressed in TPVF and FPVF is 93.01% and 0.22%, and all foot bones for all subjects are 93.75% and 0.28%, respectively. While the delineations for the four organs can be accomplished quite rapidly with average of 78 s, the delineations for the five foot bones can be accomplished with average of 70 s.Conclusions: The experimental results showed the feasibility and efficacy of the proposed automatic anatomy segmentation system: (a) the incorporation of shape priors into the GC framework is feasible in 3D as demonstrated previously for 2D images; (b) our results in 3D confirm the accuracy behavior observed in 2D. The hybrid strategy IGCASM seems to be more robust and accurate than ASM and GC individually; and (c) delineations within body regions and foot bones of clinical importance can be accomplished quite rapidly within 1.5 min.
Possibility of using cylindrical ionization chambers for percent depth‐dose measurements in clinical electron beams
Authors: Ono Takeshi , Araki Fujio , Yoshiyama Fumiaki
Published: July 2011

Purpose:

This study investigated the possibility of using cylindrical ionization chambers for percent depth‐dose (PDD) measurements in high‐energy clinical electron beams.

Methods:

The cavity correction factor,Pcav, for cylindrical chambers with various diameters was calculated as a function of depth from the surface to R50, in the energy range of 6–18 MeV electrons with the EGSnrc C ++ ‐based user‐code CAVITY. The results were compared with those for IBA NACP‐02 and PTW Roos parallel‐plate ionization chambers. The effective point of measurement (EPOM) for the cylindrical chamber and the parallel‐plate chamber was positioned according to the IAEA TRS‐398 code of practice. The overall correction factor, PQ, and the percent depth‐ionization (PDI) curve for a PTW30013 Farmer‐type chamber were also compared with those of NACP‐02 and Roos chambers.

Results:

ThePcav values at depths between the surface and R50 for cylindrical chambers were all lower than those with parallel‐plate chambers. However, the variation in depth for cylindrical chambers equal to or less than 4 mm in diameter was equivalent to or smaller than that for parallel‐plate chambers. The PQ values for the PTW30013 chamber mainly depended on Pcav, and for parallel‐plate chambers depended on the wall correction factor, Pwall, rather than Pcav. PQ at depths from the surface to R50 for the PTW30013 chamber was consequently a lower value than that with parallel‐plate chambers. However, the variation in depth was equivalent to that of parallel‐plate chambers at electron energies equal to or greater than 9 MeV. The shift to match calculated PDI curves for the PTW30013 chamber and water (perturbation free) varied from 0.65 to 0 mm between 6 and 18 MeV beams. Similarly, the shifts for NACP‐02 and Roos chambers were 0.5–0.6 mm and 0.2–0.3 mm, respectively, and were nearly independent of electron energy.

Conclusions:

Calculated PDI curves for PTW30013, NACP‐02, and Roos chambers agreed well with that of water by using the optimal EPOM. Therefore, the possibility of using cylindrical ionization chambers can be expected for PDD measurements in clinical electron beams.
Protective effects of peoniflorin against hydrogen peroxide-induced oxidative stress in human umbilical vein endothelial cells
Authors: Chen Tao , Guo Zai-pei , Jiao Xiao-yan , Zhang Yu-hong , Li Jing-yi , Liu Hong-jie
Published: July 2011

Peoniflorin (PF), extracted from the root of Paeonia lactiflora Pall., has been reported to have anti-inflammation and antioxidant effects in several animal models. Herein, we investigated the protective effects of PF against hydrogen peroxide (H2O2)-induced oxidative damage in human umbilical vein endothelial cells (HUVECs). HUVECs were treated by H2O2(240 µmol/L) with or without PF. PF significantly increased the percent cell viability of HUVECs injured by H2O2using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. By flow cytometric analysis, PF markedly attenuated H2O2-induced apoptosis and intracellular reactive oxygen species production. In addition, PF also displayed a dose-dependent reduction of lactate dehydrogenase leakage, malondialdehyde formation, and caspase-3 proteolytic activities in H2O2-treated cells, which was accompanied with a restoration of the activities of endogenous antioxidants, including total superoxide dismutase and glutathione peroxidase. Finally, Western blot data revealed that H2O2upregulated phosphorylation of extracellular signal-regulated kinase 1/2 in HUVECs, which was almost completely reversed by PF. Taken together, our data provide the first evidence that PF has a protective ability against oxidative damage in HUVECs. PF may be a candidate medicine for the treatment of vascular diseases associated with oxidative stress.
Subcutaneous adipose tissue metabolism and pharmacology: a new investigative technique
Authors: Martin Elizabeth , Brassard Pascal , Gagnon-Auger Maude , Yale Philippe , Carpentier André C. , Ardilouze Jean-Luc
Published: July 2011

According to the Fick principle, any metabolic or hormonal exchange through a given tissue depends on the product of blood flow by arteriovenous difference. Because adipose tissue plays dual storage and endocrine roles, regulation of adipose tissue blood flow (ATBF) is of pivotal importance. Monitoring ATBF in humans can be achieved through different methodologies, such as the 133Xe washout technique, considered to be the “gold standard”, as well as microdialysis and other methods that are not well validated as of yet. This report describes a new method, called “adipose tissue microinfusion” or “ATM”, which simultaneously quantifies ATBF by combining the 133Xe washout technique together with variations of ATBF induced by local infusion of vasoactive agents. The most appropriate site for ATM investigation is the subcutaneous adipose tissue of the anterior abdominal wall. This innovative method conveniently enables the direct comparison of the effects on ATBF of any vasoactive compound, drug, or hormone against a contralateral saline control. The ATM method improves the accuracy and feasibility of physiological and pharmacological studies on the regulation of ATBF in vivo in humans.
Extract of the plantCotinus coggygriaScop. attenuates pyrogallol-induced hepatic oxidative stress in Wistar rats
Authors: Matić Sanja , Stanić Snežana , Bogojević Desanka , Vidaković Melita , Grdović Nevena , Arambašić Jelena , Dinić Svetlana , Uskoković Aleksandra , Poznanović Goran , Solujić Slavica , Mladenović Milan , Marković Jelena , Mihailović Mirjana
Published: July 2011

To examine the protective potential of the Cotinus coggygria Scop. methanol extract, Wistar rats were treated with the hepatotoxic compound pyrogallol, which possesses a potent ability to generate free radicals and induce oxidative stress. The ability of the extract to counteract the oxidative stress was examined in rats that were injected with the extract intraperitoneally (500 mg·(kg body weight)–1) either 2 or 12 h before the pyrogallol treatment. The extract possesses a reducing activity in vitro and an ability to chelate the ferrous ion both in vivo and in vitro. Application of the extract prior to pyrogallol treatment led to a decrease in the levels of thiobarbituric acid-reactive substances, aspartate aminotransferase, and alanine aminotransferase, increased activities of antioxidant enzymes and attenuation of DNA damage, as well as increased Akt activity and inhibition of NF-κB protein expression. Treatment with the extract 12 h prior to pyrogallol administration was more effective in suppressing pyrogallol-induced oxidative damage than the 2 h pretreatment. Extract administration promoted an increase in acute phase reactants haptoglobin and α2-macroglobulin that was short of a full-fledged acute phase response. Administration of the extract considerably improved the markers of oxidative stress, thus revealing a potential hepatoprotective activity. Our results suggest that Akt activation, NF-κB inhibition, and induction of the acute phase play important roles in mediating hepatic protection by the extract. The greater effectiveness of the 12 h pretreatment with extract points to the important role that preconditioning assumes in improving resistance to subsequent exposure to oxidative stress.
Immunomodulatory activity ofLactobacillusstrains isolated from fermented vegetables and infant stool
Authors: Won Tae Joon , Kim Bongjoon , Oh Eun Seul , Bang Joon Seok , Lee Yoon Jeong , Yoo Jong-Sun , Yu Hyunmin , Yoon Joowon , Hyung Kyeong Eun , Park So-Young , Hwang Kwang Woo
Published: July 2011

Four Lactobacillus strains — Lactobacillus plantarum CJLP133, L. plantarum CJLP243, L. plantarum CJNR26, and Lactobacillus gasseri CJMF3 — were isolated from Korean fermented food or healthy infant feces, and their capacity to modulate cellular and humoral immune responses was studied. Feeding of the tested lactobacilli for 8 weeks did not alter the weight of and cell numbers in the spleen of mice. However, CJLP133 and CJLP243 strains increased the T lymphocyte population in the spleen of mice, while CJNR26 and CJMF3 increased the B lymphocyte population. In splenocytes treated with concanavalin A, ingestion of CJLP133 and CJLP243 promoted T lymphocyte proliferation and secretion of T cell cytokines, whereas feeding of the CJNR26 and CJMF3 strains enhanced B lymphocyte proliferation in splenocytes treated with lipopolysaccharide and plaque formation. These results suggest that CJLP133 and CJLP243 have immunostimulating activity through the enhancement of T cell activation, while CJNR26 and CJMF3 exhibit immunopotentiation through the increment of B cell activation.
VECTOR AND AXIAL-VECTOR CORRELATORS AND THE FOUR-QUARK CONDENSATE
Authors: CHEN LI-AN , HE LONG-QING
Published: July 2011

In this paper we calculate the difference between vector and axial-vector correlators with two different vertices: the bare vertex and the Ball–Chiu vertex (BC vertex) ansatz. Through the difference we compare the results drawn from the chiral sum rules. The leading nonzero contribution of the difference of the correlators in the ultraviolet identifies the four-quark condensate, which is the leading nonperturbative phenomenon in QCD. Also the pion decay constant can be drawn. For the quark propagator, we employ two different models. One is calculated in the framework of the rainbow-ladder approximation scheme in the Dyson–Schwinger approach. The other is the analytic fit employed in Ref. 1. Results show that the dressing effects of the vector and axial-vector vertices are very important.
LINEAR ENERGY DIVERGENCES IN COULOMB GAUGE QCD
Authors: ANDRAŠI A.
Published: July 2011

The structure of linear energy divergences is analyzed on the example of one graph to three-loop order. Such dangerous divergences do cancel when all graphs are added, but next-to-leading divergences do not cancel out.
UNCERTAIN CONTEXT FACTORS IN ERP PROJECT ESTIMATION ARE AN ASSET: INSIGHTS FROM A SEMI-REPLICATION CASE STUDY IN A FINANCIAL SERVICES FIRM
Authors: DANEVA MAYA
Published: July 2011

This paper reports on the findings of a case study in a company in the financial services sector in which we replicated the use of a previously published approach to systematically balance the contextual uncertainties in the estimation of Enterprise Resource Planning (ERP) projects. The approach is based on using three techniques, a parametric model, namely COCOMO II, a portfolio management model, and Monte Carlo simulations. We investigated (i) whether the adjustment of uncertain cost drivers in the COCOMO II model increases the chance of project success in a portfolio of ERP projects, (ii) which cost drivers of the COCOMO II model can be adjusted in a way that maximized the chance of portfolio success under time constraints, and (iii) which cost drivers of the COCOMO II model can be adjusted in a way that maximized the chance of portfolio success under effort constraints. We found that 11 COCOMO II cost drivers can be changed so that the change impacts the project outcomes under both time and effort constraints. This result is different from the result in the first case study in which 13 such factors were found.
REDUCED BASIS APPROXIMATION AND A POSTERIORI ERROR ESTIMATION FOR THE PARAMETRIZED UNSTEADY BOUSSINESQ EQUATIONS
Authors: KNEZEVIC DAVID J. , NGUYEN NGOC-CUONG , PATERA ANTHONY T.
Published: July 2011

In this paper we present reduced basis (RB) approximations and associated rigorous a posteriori error bounds for the parametrized unsteady Boussinesq equations. The essential ingredients are Galerkin projection onto a low-dimensional space associated with a smooth parametric manifold — to provide dimension reduction; an efficient proper orthogonal decomposition–Greedy sampling method for identification of optimal and numerically stable approximations — to yield rapid convergence; accurate (online) calculation of the solution-dependent stability factor by the successive constraint method — to quantify the growth of perturbations/residuals in time; rigorous a posteriori bounds for the errors in the RB approximation and associated outputs — to provide certainty in our predictions; and an offline–online computational decomposition strategy for our RB approximation and associated error bound — to minimize marginal cost and hence achieve high performance in the real-time and many-query contexts. The method is applied to a transient natural convection problem in a two-dimensional "complex" enclosure — a square with a small rectangle cutout — parametrized by Grashof number and orientation with respect to gravity. Numerical results indicate that the RB approximation converges rapidly and that furthermore the (inexpensive) rigorous a posteriori error bounds remain practicable for parameter domains and final times of physical interest.
MATHEMATICAL ANALYSIS AND NUMERICAL METHODS FOR A PARTIAL DIFFERENTIAL EQUATIONS MODEL GOVERNING A RATCHET CAP PRICING IN THE LIBOR MARKET MODEL
Authors: PASCUCCI A. , SUÁREZ-TABOADA M. , VÁZQUEZ C.
Published: July 2011

In this paper, we present a mathematical model for pricing a particular financial product: the ratchet cap. This derivative product depends on certain interest rates (whose dynamics we assume that follow the LIBOR market model). The pricing model is rigorously posed in terms of a sequence of nested Cauchy problems associated to uniformly parabolic partial differential equations. First, for each problem the existence and uniqueness of solution is obtained. Next, this analysis allows to propose a new and more efficient numerical method based on the approximation by computable fundamental solutions of constant coefficient operators. The advantage in terms of computational time of this new modeling and analytically based approach is illustrated by comparison with the classically used Monte Carlo simulation and a characteristics Crank–Nicolson time discretization combined with finite elements strategy.
ABLATIVE HELE–SHAW MODEL FOR ICF FLOWS MODELING AND NUMERICAL SIMULATION
Authors: EGLY HUGUES , DESPRÉS BRUNO , SENTIS REMI
Published: July 2011

We propose a model for the study of ablation fronts encountered in inertial confinement fusion flows. Following the ideas of physicists specially Sanz's ones, we try to justify the modeling of this problem by a Hele–Shaw equation posed in the complement of a bounded domain the boundary of which is evolving with time. This equation is coupled with an advection equation for the vorticity of the fluid. We propose a numerical strategy based on the fat boundary method to discretize the system and we present some numerical results which show that the numerical method is feasible to simulate ablative Raleigh–Taylor instabilities in the context of these plasma flows.
NULLIFICATION OF KNOTS AND LINKS
Authors: DIAO YUANAN , ERNST CLAUS , MONTEMAYOR ANTHONY
Published: July 2011

It is known that a knot/link can be nullified, i.e. can be made into the trivial knot/link, by smoothing some crossings in a projection diagram of the knot/link. The nullification of knots/links is believed to be biologically relevant. For example, in DNA topology, the nullification process may be the pathway for a knotted circular DNA to unknot itself (through recombination of its DNA strands). The minimum number of such crossings to be smoothed in order to nullify the knot/link is called the nullification number. It turns out that there are several different ways to define such a number, since different conditions may be applied in the nullification process. We show that these definitions are not equivalent, thus they lead to different nullification numbers for a knot/link in general, not just one single nullification number. Our aim is to explore some mathematical properties of these nullification numbers. First, we give specific examples to show that the nullification numbers we defined are different. We provide a detailed analysis of the nullification numbers for the well known 2-bridge knots and links. We also explore the relationships among the three nullification numbers, as well as their relationships with other knot invariants. Finally, we study a special class of links, namely those links whose general nullification number equals one. We show that such links exist in abundance. In fact, the number of such links with crossing number less than or equal to n grows exponentially with respect to n.
INFINITELY MANY SOLUTIONS FOR THE DIRICHLET PROBLEM ON THE SIERPINSKI GASKET
Authors: BRECKNER BRIGITTE E. , RĂDULESCU VICENŢIU D. , VARGA CSABA
Published: July 2011

We study the nonlinear elliptic equation Δu(x) + a(x)u(x) = g(x)f(u(x)) on the Sierpinski gasket and with zero Dirichlet boundary condition. By extending a method introduced by Faraci and Kristály in the framework of Sobolev spaces to the case of function spaces on fractal domains, we establish the existence of infinitely many weak solutions.
CLASSES OF FUNCTIONS WITH IMPROVED ESTIMATES IN APPROXIMATION BY THE MAX-PRODUCT BERNSTEIN OPERATOR
Authors: COROIANU LUCIAN , GAL SORIN G.
Published: July 2011

In this paper, we find large classes of positive functions, others than those in [1], having even a Jackson-type estimate, ω1(f;1/n), in approximation by the nonlinear max-product Bernstein operator. The uniform estimate of the order O[nω1(f;1/n)2 + ω1(f;1/n)] is achieved, while near to the endpoints 0 and 1, the better pointwise estimate of the order [Formula: see text] is obtained. Finally, we prove that besides the preservation of quasi-convexity found in [1], the nonlinear max-product Bernstein operator preserves the quasi-concavity too.
DYNAMICS OF A STOCHASTIC RATIO-DEPENDENT PREDATOR-PREY MODEL
Authors: LINH NGUYEN THI HOAI , TON TA VIET
Published: July 2011

In this paper, we consider a stochastic ratio-dependent predator-prey model. We firstly prove the existence, uniqueness and positivity of the solutions. Then, the boundedness of moments of population are studied. Finally, we show the upper-growth rates and exponential death rates of population under some conditions.
On the Travelling Waves for the Generalized Nonlinear Schrödinger Equation
Authors: Hasanov Mahir
Published: July 2011

This paper is devoted to the analysis of the travelling waves for a
class of generalized nonlinear Schrödinger equations in a cylindric domain. Searching for travelling waves reduces the problem to the multiparameter eigenvalue problems for a class of perturbed p‐Laplacians.
We study dispersion relations between the eigenparameters, quantitative analysis of eigenfunctions and discuss some variational principles for eigenvalues of perturbed p‐Laplacians. In this paper we analyze the Dirichlet, Neumann, No‐flux, Robin and Steklov boundary value problems. Particularly, a “duality principle” between the Robin and the Steklov problems is presented.
Complementary and Alternative Exercises for Management of Osteoarthritis
Authors: Chyu Ming-Chien , von Bergen Vera , Brismée Jean-Michel , Zhang Yan , Yeh James K. , Shen Chwan-Li
Published: July 2011

Osteoarthritis (OA) is a chronic condition characterized by degeneration of cartilage and its underlying bone within a joint. With no cure currently available, the goals of treating OA are to alleviate pain, maintain, or improve joint mobility, increase the muscle strength of the joints, and minimize the disabling effects of the disease. Recent research has suggested that complementary and alternative medicine (CAM) exercises may improve OA symptoms. This paper covers CAM mind-body exercises—Tai Chi, qigong, and yoga—for OA management and evaluates their benefits in pain reduction, muscle strength, physical function, stiffness, balance, fear of falling, self-efficacy, quality of life, and psychological outcomes in patients with OA, based on randomized controlled trials published. Findings from the literature suggest that CAM exercises demonstrate considerable promise in the management of OA. Future studies require rigorous randomized controlled trials with larger sample sizes.
Association of Influenza Virus Proteins with Membrane Rafts
Authors: Veit Michael , Thaa Bastian
Published: July 2011

Assembly and budding of influenza virus proceeds in the viral budozone, a domain in the plasma membrane with characteristics of cholesterol/sphingolipid-rich membrane rafts. The viral transmembrane glycoproteins hemagglutinin (HA) and neuraminidase (NA) are intrinsically targeted to these domains, while M2 is seemingly targeted to the edge of the budozone. Virus assembly is orchestrated by the matrix protein M1, binding to all viral components and the membrane. Budding progresses by protein- and lipid-mediated membrane bending and particle scission probably mediated by M2. Here, we summarize the experimental evidence for this model with emphasis on the raft-targeting features of HA, NA, and M2 and review the functional importance of raft domains for viral protein transport, assembly and budding, environmental stability, and membrane fusion.
The Role of Proteomics in the Diagnosis and Treatment of Women's Cancers: Current Trends in Technology and Future Opportunities
Authors: Breuer Eun-Kyoung Yim , Murph Mandi M.
Published: July 2011

Technological and scientific innovations over the last decade have greatly contributed to improved diagnostics, predictive models, and prognosis among cancers affecting women. In fact, an explosion of information in these areas has almost assured future generations that outcomes in cancer will continue to improve. Herein we discuss the current status of breast, cervical, and ovarian cancers as it relates to screening, disease diagnosis, and treatment options. Among the differences in these cancers, it is striking that breast cancer has multiple predictive tests based upon tumor biomarkers and sophisticated, individualized options for prescription therapeutics while ovarian cancer lacks these tools. In addition, cervical cancer leads the way in innovative, cancer-preventative vaccines and multiple screening options to prevent disease progression. For each of these malignancies, emerging proteomic technologies based upon mass spectrometry, stable isotope labeling with amino acids, high-throughput ELISA, tissue or protein microarray techniques, and click chemistry in the pursuit of activity-based profiling can pioneer the next generation of discovery. We will discuss six of the latest techniques to understand proteomics in cancer and highlight research utilizing these techniques with the goal of improvement in the management of women's cancers.
Site Assessment of Multiple-Sensor Approaches for Buried Utility Detection
Authors: Royal Alexander C. D. , Atkins Phil R. , Brennan Michael J. , Chapman David N. , Chen Huanhuan , Cohn Anthony G. , Foo Kae Y. , Goddard Kevin F. , Hayes Russell , Hao Tong , Lewin Paul L. , Metje Nicole , Muggleton Jen M. , Naji Adham , Orlando Giovanni , Pennock Steve R. , Redfern Miles A. , Saul Adrian J. , Swingler Steve G. , Wang Ping , Rogers Christopher D. F.
Published: July 2011

The successful operation of buried infrastructure within urban environments is fundamental to the conservation of modern living standards. Open-cut methods are predominantly used, in preference to trenchless technology, to effect a repair, replace or install a new section of the network. This is, in part, due to the inability to determine the position of all utilities below the carriageway, making open-cut methods desirable in terms of dealing with uncertainty since the buried infrastructure is progressively exposed during excavation. However, open-cut methods damage the carriageway and disrupt society's functions. This paper describes the progress of a research project that aims to develop a multi-sensor geophysical platform that can improve the probability of complete detection of the infrastructure buried beneath the carriageway. The multi-sensor platform is being developed in conjunction with a knowledge-based system that aims to provide information on how the properties of the ground might affect the sensing technologies being deployed. The fusion of data sources (sensor data and utilities record data) is also being researched to maximize the probability of location. This paper describes the outcome of the initial phase of testing along with the development of the knowledge-based system and the fusing of data to produce utility maps.
Applying the Ecology Model to Perinatal Medicine: From a Regional Population-Based Study
Authors: Tokunaga Syuichi , Sameshima Hiroshi , Ikenoue Tsuyomu
Published: July 2011

Objective. Ecology model is useful to provide a framework for organizing medical care. We aimed to see if the ecology model is applicable to perinatal care in Japan.Methods. On a population-based approach, we had 53,461 deliveries in Miyazaki from 2001 to 2005. In comparison, we used all of the 106,613 deliveries in Tokyo in 2009. Women were divided into 4 grades by risk-allocation criteria and their proportion was expressed per 1,000 women to apply to the model and to delineate the ecology curve. The perinatal mortality was compared by Chi-square test.Results. We found remarkable similarity in ecology curves between the original ecology models and that representing Miyazaki perinatal data. However, the curve representing Tokyo was different from the original one. Besides, the perinatal mortality was significantly lower in Miyazaki (4.40/1,000) than in Tokyo (5.06/1,000).Conclusion. Applying the ecology model to perinatal care is useful with improvement of perinatal outcome and it would provide an appropriate framework for organizing perinatal care.
A Note on Some Strongly Sequence Spaces
Authors: Savaş Ekrem , Kılıçman Adem
Published: July 2011

We introduce and study new sequence spaces which arise from the notions of generalized de la Vallée‐Poussin means, invariant means, and modulus functions.
Electrical Modification of Combustion and the Affect of Electrode Geometry on the Field Produced
Authors: Dolmansley Timothy J. C. , Wilson Christopher W. , Stone David A.
Published: July 2011

There has been extensive work to show how electric fields can influence combustion. However, many different set ups are used. This work shows how different set ups produce different field strengths and that the field is not always uniformly distributed. The field strength is modelled using Ansys Maxwell. The type of material used is discussed and the set up of apparatus. It is recommended to use parallel plates for experimentation. Parallel plates produce the most uniform field this allow′s it′s influence to be directly investigated and related to the field strength.
ZnO and MgZnO Nanocrystalline Flexible Films: Optical and Material Properties
Authors: Huso Jesse , Morrison John L. , Che Hui , Sundararajan Jency P. , Yeh Wei Jiang , McIlroy David , Williams Thomas J. , Bergman Leah
Published: July 2011

An emerging material for flexible UV applications isMgxZn1−xO which is capable of tunable bandgap and luminescence in the UV range of ~3.4 eV–7.4 eV depending on the compositionx. Studies on the optical and material characteristics of ZnO and Mg0.3Zn0.7O nanocrystalline flexible films are presented. The analysis indicates that the ZnO and Mg0.3Zn0.7O have bandgaps of 3.34 eV and 4.02 eV, respectively. The photoluminescence (PL) of the ZnO film was found to exhibit a structural defect-related emission at ~3.316 eV inherent to the nanocrystalline morphology. The PL of the Mg0.3Zn0.7O film exhibits two broad peaks at 3.38 eV and at 3.95 eV that are discussed in terms of the solubility limit of the ZnO-MgO alloy system. Additionally, external deformation of the film did not have a significant impact on its properties as indicated by the Raman LO-mode behavior, making these films attractive for UV flexible applications.