bluuebunny/crossref_metadata_2025 huggingface dataset:
Optically Coated Mirror‐Embedded Microchannel to Measure Hydrophoretic Particle Ordering in Three Dimensions
Authors: Choi Sungyoung , Park Je‐Kyun
Published: July 2009

Three‐dimensional (3D) measurement of the behavior of microfluidic particles is vital for improving their operational efficiency and characterization. In particular, it is important to measure particle motions in 3D for exact characterization of hydrophoresis, which utilizes 3D convective flows for size separation. Herein, the 3D measurement of hydrophoretic particle ordering for the exact characterization of hydrophoresis by using an optically coated mirror‐embedded microchannel is reported. The mirror, ideally at 45°, reflects the side view of the channel and enables 3D positional information to be obtained easily from two different orthogonal‐axis images. With this method, it is shown that hydrophoresis is governed by convective vortices and steric hindrance. It is also observed that hydrophoresis enables 3D particle focusing without sheath flows and accurate flow‐rate control. The mechanism of hydrophoresis is finally verified by conducting a computational simulation and comparing the simulation results with the experimental measurements. The hydrophoretic method can be straightforwardly integrated as a 3D particle‐focusing component in integrated microfluidic systems. The mirror‐embedded channel can also be readily fabricated in a single cast of polydimethylsiloxane, thus offering low‐cost, easy implementation of 3D particle measurement.
Reflections on the virtues of modularity: a case study in linux security modules
Authors: Blaich Andrew , Thain Douglas , Striegel Aaron
Published: July 2009

Developing a modular system that properly supports a range of security models is challenging. The work presented here details our experiences with the modularLinuxsecurity framework called Linux Security Modules, or LSMs. Throughout our experiences we discovered that the developers of the LSM framework made certain tradeoffs for speed and simplicity during implementation, and consequently leaving the framework incomplete. Our experiences show at which points the theory of the LSM differs from reality, and details how these differences play out when developing and using a custom LSM. Copyright © 2009 John Wiley & Sons, Ltd.
Engineering perspectives on healthcare delivery: Can we afford technological innovation in healthcare?
Authors: Rouse William B.
Published: July 2009

This article considers the national challenge of controlling healthcare costs. It is argued that this system‐level challenge is better addressed with an engineering approach rather than from the perspective of medical science that, quite rightly, is tailored to address clinical practice. The engineering approach is outlined and three models are proposed for controlling the costs of healthcare so that the growth of these costs tracks the growth of gross domestic product. These models provide insights into the magnitude of efficiency gains needed to accomplish this goal. Possible ways to achieve these gains are discussed. Copyright © 2009 John Wiley & Sons, Ltd.
Fast Dynamic Exchange between Na+OH– Ion Pairs and H2O Molecules in Sodalites
Authors: Mangir Murshed M. , Gesing Thorsten M.
Published: July 2009

We report sodalite phases formed at the intermediate stages during the fast dynamic exchange between Na+OH– ion pairs and H2O molecules while transforming a series of hydro‐hydroxy sodalites into hydro sodalites. The applicability of an ion‐exchange technique has been addressed, which is much faster than the previously employed exchange methods. The results of X‐ray diffraction, FTIR and 1H MAS NMR spectroscopy are complimentary showing the successive steps of the exchanges. The X‐ray data Rietveld refinements demonstrate that the framework composition did not change at the intermediate stages of the Na+OH–/H2O exchange, thus distinguished the ion‐exchange from recrystallization.
High-dimensional Exploratory Item Factor Analysis by A Metropolis–Hastings Robbins–Monro Algorithm
Authors: Cai Li
Published: July 2009

A Metropolis–Hastings Robbins–Monro (MH-RM) algorithm for high-dimensional maximum marginal likelihood exploratory item factor analysis is proposed. The sequence of estimates from the MH-RM algorithm converges with probability one to the maximum likelihood solution. Details on the computer implementation of this algorithm are provided. The accuracy of the proposed algorithm is demonstrated with simulations. As an illustration, the proposed algorithm is applied to explore the factor structure underlying a new quality of life scale for children. It is shown that when the dimensionality is high, MH-RM has advantages over existing methods such as numerical quadrature based EM algorithm. Extensions of the algorithm to other modeling frameworks are discussed.
Binding Energy and Spin-Orbit Splitting of a Hydrogenic Donor Impurity in AlGaN/GaN Triangle-Shaped Potential Quantum Well
Authors: Wang Jun , Li Shu-Shen , Lü Yan-Wu , Liu Xiang-Lin , Yang Shao-Yan , Zhu Qin-Sheng , Wang Zhan-Guo
Published: July 2009

In the framework of effective-mass envelope function theory, including the effect of Rashba spin-orbit coupling, the binding energyE

b
and spin-orbit split energy Г of the ground state of a hydrogenic donor impurity in AlGaN/GaN triangle-shaped potential heterointerface are calculated. We find that with the electric field of the heterojunction increasing, (1) the effective width of quantum well "Equation missing"decreases and (2) the binding energy increases monotonously, and in the mean time, (3) the spin-orbit split energy Г decreases drastically. (4) The maximum of Г is 1.22 meV when the electric field of heterointerface is 1 MV/cm.
WEAK BRAIDED BIALGEBRAS AND WEAK ENTWINING STRUCTURES
Authors: ALONSO ÁLVAREZ J. N. , FERNÁNDEZ VILABOA J. M. , GONZÁLEZ RODRÍGUEZ R.
Published: July 2009

In this paper we clarify and improve the notion of weak braided bialgebra using weak entwining structures. As a main result we show that the notion of weak braided bialgebra can be rewritten in terms of weak entwining structures.
Experimental rat models to study the metabolic syndrome
Authors: Aleixandre de Artiñano Amaya , Miguel Castro Marta
Published: July 2009

Being the metabolic syndrome a multifactorial condition, it is difficult to find adequate experimental models to study this pathology. The obese Zucker rats, which are homozygous for thefaallele, present abnormalities similar to those seen in human metabolic syndrome and are a widely extended model of insulin resistance. The usefulness of these rats as a model of non-insulin-dependent diabetes mellitus is nevertheless questionable, and they neither can be considered a clear experimental model of hypertension. Some experimental models different from the obese Zucker rats have also been used to study the metabolic syndrome. Some derive from the spontaneously hypertensive rats (SHR). In this context, the most important are the obese SHR, usually named Koletsky rats. Hyperinsulinism, associated with either normal or slightly elevated levels of blood glucose, is present in these animals, but SHR/N-corpulent rats are a more appropriated model of non-insulin-dependent diabetes mellitus. The SHR/NDmc corpulent rats, a subline of SHR/N-corpulent rats, also exhibit metabolic and histopathologic characteristics associated with human metabolic disorders. A new animal model of the metabolic syndrome, stroke-prone–SHR (SHRSP) fatty rats, was obtained by introducing a segment of the mutant leptin receptor gene from the Zucker line heterozygous for thefagene mutation into the genetic background of the SHRSP. Very recently, it has been developed as a non-obese rat model with hypertension, fatty liver and characteristics of the metabolic syndrome by transgenic overexpression of a sterol-regulatory element-binding protein in the SHR rats. The Wistar Ottawa Karlsburg W rats are also a new strain that develops a nearly complete metabolic syndrome. Moreover, a new experimental model of low-capacity runner rats has also been developed with elevated blood pressure levels together with the other hallmarks of the metabolic syndrome.
A fundamental limit on the balance of power in a transpiration-controlled channel flow
Authors: BEWLEY THOMAS R.
Published: July 2009

This paper is a direct sequel to Bewley & Aamo (J. Fluid Mech., vol. 499, 2004, pp. 183–196). It was conjectured in that paper, based on the numerical evidence available at that time, that the minimum drag of a constant mass flux channel flow might in fact be that of the laminar flow. This conjecture turned out to be false; Min et al. (J. Fluid Mech., vol. 558, 2006, 309318) discovered a curious control strategy which in fact reduces the time-averaged drag to sub-laminar levels. The present paper establishes rigorously that the power of the control input applied at the walls is always larger than the power saved (due to drag reduction below the laminar level) for any possible control distribution, including that proposed by Min et al. (2006), thus establishing that, energetically (that is accounting for the power saved due to drag reduction and the power exerted by application of the control), the optimal control solution is necessarily to relaminarize the flow.
Measurements of molecular mixing in a high-Schmidt-number Rayleigh–Taylor mixing layer
Authors: MUESCHKE NICHOLAS J. , SCHILLING OLEG , YOUNGS DAVID L. , ANDREWS MALCOLM J.
Published: July 2009

Molecular mixing measurements are reported for a high-Schmidt-number (Sc~ 103), small-Atwood-number (A≈ 7.5 × 10−4) buoyancy-driven turbulent Rayleigh–Taylor (RT) mixing layer in a water channel facility. Salt was added to the top water stream to create the desired density difference. The degree of molecular mixing was measured as a function of time by monitoring a diffusion-limited chemical reaction between the two fluid streams. The pH of each stream was modified by the addition of acid or alkali such that a local neutralization reaction occurred as the two fluids molecularly mixed. The progress of this neutralization reaction was tracked by the addition of phenolphthalein – a pH-sensitive chemical indicator – to the acidic stream. Accurately calibrated backlit optical techniques were used to measure the average concentration of the coloured chemical indicator. Comparisons of chemical product formation for pre-transitional buoyancy- and shear-driven mixing layers are given. It is also shown that experiments performed at different equivalence ratios (acid/alkali concentrations) can be combined to obtain a mathematical relationship between the coloured product formed and the density variance. This relationship was used to obtain high-fidelity quantitative measures of the degree of molecular mixing which are independent of probe resolution constraints. The dependence of molecular mixing on the Schmidt and Reynolds numbers is examined by comparing the currentSc~ 103measurements with previousSc= 0.7 gas-phase andPr= 7 (wherePris the Prandtl number) liquid-phase measurements. This comparison indicates that the Schmidt number has a large effect on the quantity of mixed fluid at small Reynolds numbersReh< 103. At larger Reynolds numbers, corresponding to later times in this experiment, all mixing parameters indicated a greater degree of molecular mixing and a decreased Schmidt number dependence. Implications for the development and quantitative assessment of turbulent transport and mixing models appropriate for RT instability-induced mixing are discussed.
High-speed unsteady flows around spiked-blunt bodies
Authors: PANARAS ARGYRIS G. , DRIKAKIS DIMITRIS
Published: July 2009

This paper presents a detailed investigation of unsteady supersonic and hypersonic flows around spiked-blunt bodies, including the investigation of the effects of the flow field initialization on the flow results. Past experimental research has shown that if the geometry of a spiked-blunt body is such that a shock formation consisting of an oblique foreshock and a bow aftershock appears, then the flow may be unsteady. The unsteady flow is characterized by periodic radial inflation and collapse of the conical separation bubble formed around the spike (pulsation). Beyond a certain spike length the flow is ‘stable’, i.e. steady or mildly oscillating in the radial direction. Both unsteady and ‘stable’ conditions have been reported when increasing or decreasing the spike length during an experimental test and, additionally, hysteresis effects have been observed. The present study reveals that for certain geometries the numerically simulated flow depends strongly on the assumed initial flow field, including the occurrence of bifurcations due to inherent hysteresis effects and the appearance of unsteady flow modes. Computations using several different configurations reveal that the transient (initial) flow development corresponds to a nearly inviscid flow field characterized by a foreshock–aftershock interaction. When the flow is pulsating, the further flow development is not sensitive to initial conditions, whereas for an oscillating or almost ‘steady’ flow, the flow development depends strongly on the assumed initial flow field.
Axisymmetric and non-axisymmetric instability of an electrified viscous coaxial jet
Authors: LI FANG , YIN XIE-YUAN , YIN XIE-ZHEN
Published: July 2009

A linear study is carried out for the axisymmetric and non-axisymmetric instability of a viscous coaxial jet in a radial electric field. The outer liquid is considered to be a leaky dielectric and the inner a perfect dielectric. The generalized eigenvalue problem is solved and the growth rate of disturbance is obtained by using Chebyshev spectral collocation method. The effects of the radial electric field, liquid viscosity, surface tension as well as other parameters on the instability of the jet are investigated. The radial electric field is found to have a strong destabilizing effect on non-axisymmetric modes, especially those having smaller azimuthal wavenumbers. The helical mode becomes prevalent over other modes when the electric field is sufficiently large. Non-axisymmetric modes with high azimuthal wavenumbers may be the most unstable at zero wavenumber. Liquid viscosity has a strong stabilizing effect on both the axisymmetric and non-axisymmetric instability. Relatively, the helical instability is less suppressed and therefore becomes predominant at high liquid viscosity. Surface tension promotes the instability of the para-sinuous mode and meanwhile suppresses the helical and the other non-axisymmetric modes in long wavelength region.
The role of angular momentum conservation in homogeneous turbulence
Authors: DAVIDSON P. A.
Published: July 2009

Loitsyanky's integral I = − ∫ r2〈u ⋅u′〉dr is known to be approximately conserved in certain types of fully developed, isotropic turbulence, and its near conservation controls the rate of decay of kinetic energy. Landau suggested that this integral is related to the angular momentum H = ∫ (x × u)dV of some large volume V of the turbulence, according to the expression I = 〈H2〉/V. He also suggested that the approximate conservation of I is related to the principle of conservation of angular momentum. However, Landau's analysis can be criticized because, formally, it applies only to inhomogeneous turbulence evolving in a closed domain. So how are we to interpret the near conservation of I? And what is its relationship, if any, to angular momentum conservation? We show that the key to extending Landau's analysis to strictly homogeneous turbulence is to rewrite Loitsyansky's integral in terms of the vector potential of the velocity field, i.e. I = 6 ∫〈A ⋅ A′〉dr, where ∇ × A = u. This yields I = 6〈[∫VAdV]2〉/V for any large spherical volume V of radius R. Crucially, J = 3∫VAdV can be rewritten as the weighted integral of the angular momentum density throughout all space. This fundamentally changes the way in which we interpret the dynamical behaviour of I. For example, we show that the conservation of 〈J2〉/V, and hence of I, which occurs when the long-range correlations are weak, is a direct consequence of the decorrelation of the flux of angular momentum out through a spherical control surface S and the local angular momentum in the vicinity of S. Thus, within the framework of strictly homogeneous turbulence, we provide the first self-consistent interpretation of Loitsyanky's integral in terms of angular momentum conservation. We also show that essentially the same ideas carry over to certain types of anisotropic turbulence, such as magnetohydrodynamic (MHD), rotating and stratified turbulence. This is important because conservation of angular momentum, which manifests itself in the form of a Loitsyansky-like invariant, places a fundamental restriction on the way in which the integral scales can evolve in such turbulence. This, in turn, controls the rate of decay of energy. We illustrate this by deriving new decay laws for MHD and stratified turbulence. The MHD decay laws are consistent with the available numerical evidence, but further study is required to verify, or otherwise, the predictions for stratified turbulence.
Time-dependent linear water-wave scattering in two dimensions by a generalized eigenfunction expansion
Authors: MEYLAN MICHAEL H.
Published: July 2009

We consider the solution in the time domain of the two-dimensional water-wave scattering by fixed bodies, which may or may not intersect with the free surface. We show how the problem with arbitrary initial conditions can be found from the single-frequency solutions using a generalized eigenfunction expansion, required because the operator has a continuous spectrum. From this expansion we derive simple formulas for the evolution in time of the initial surface conditions, and we present some examples of numerical calculations.
Global stability of flow past a cylinder with centreline symmetry
Authors: KUMAR BHASKAR , KOTTARAM JACOB JOHN , SINGH AMIT KUMAR , MITTAL SANJAY
Published: July 2009

Global absolute and convective stability analysis of flow past a circular cylinder with symmetry conditions imposed along the centreline of the flow field is carried out. A stabilized finite element formulation is used to solve the eigenvalue problem resulting from the linearized perturbation equation. All the computations carried out are in two dimensions. It is found that, compared to the unrestricted flow, the symmetry conditions lead to a significant delay in the onset of absolute as well as convective instability. In addition, the onset of absolute instability is greatly affected by the location of the lateral boundaries and shows a non-monotonic variation. Unlike the unrestricted flow, which is associated with von Kármán vortex shedding, the flow with centreline symmetry becomes unstable via modes that are associated with low-frequency large-scale structures. These lead to expansion and contraction of the wake bubble and are similar in characteristics to the low-frequency oscillations reported earlier in the literature. A global linear convective stability analysis is utilized to find the most unstable modes for different speeds of the disturbance. Three kinds of convectively unstable modes are identified. The ones travelling at very low streamwise speed are associated with large-scale structures and relatively low frequency. Shear layer instability, with relatively smaller scale flow structures and higher frequency, is encountered for disturbances travelling at relatively larger speed. For low blockage a new type of instability is found. It travels at relatively high speed and resembles a swirling flow structure. As opposed to the absolute instability, the convective instability appears at much lowerReand its onset is affected very little by the location of the lateral boundaries. Analysis is also carried out for determining the convective stability of disturbances that travel in directions other than along the free stream. It is found that the most unstable disturbances are not necessarily the purely streamwise travelling ones. Disturbances that move purely in the cross-stream direction can also be convectively unstable. The results from the linear stability analysis are confirmed by carrying out direct time integration of the linearized disturbance equations. The disturbance field shows transient growth by several orders of magnitude confirming that such flows act as amplifiers. Direct time integration of the Navier–Stokes equation is carried out to track the time evolution of both the large-scale low-frequency oscillations and small-scale shear layer instabilities. The criticalRefor the onset of convective instability is compared with earlier results from local analysis. Good agreement is found.
Separation-driven coalescence of droplets: an analytical criterion for the approach to contact
Authors: LAI ANN , BREMOND NICOLAS , STONE HOWARD A.
Published: July 2009

Recent microfluidic experiments by Bremond, Thiam & Bibette (Phys. Rev. Lett., vol. 100, 2008, paper no. 024501), along with simulations by Yoon et al. (Phys. Fluid, vol. 19, 2007, paper no. 102102) and near-contact experiments and simulations by Manica et al. (Langmuir, vol. 24, 2008, pp. 1381–1390), have demonstrated that two droplets can coalesce as they are separating rather than upon their collision. We analyse the experimental microfluidic flow configuration for the approach to contact with a two-dimensional model: we apply a lubrication analysis followed by the method of domain perturbation to determine the droplet deformation as a function of time. We find the approximate shape for the deformed droplet at the time of contact. In particular, for droplets of radius R, moving apart according to h0(t) = h0(0) + αt2, where 2h0(t) is the separation distance, we define a non-dimensional parameter A=4CμR2α1/2/πγ[h0(0)]3/2, where μ is the viscosity of the continuous phase; γ is the interfacial tension; and C depends on the viscosity ratio between the droplets and the continuous phase. Our model suggests that there exists a critical value Acrit = 16/33/2 ≈ 3.0792, below which separation is unlikely to facilitate the coalescence of the droplets. The predictions are in good agreement with available experimental data.
A comparison of turbulent pipe, channel and boundary layer flows
Authors: MONTY J. P. , HUTCHINS N. , NG H. C. H. , MARUSIC I. , CHONG M. S.
Published: July 2009

The extent or existence of similarities between fully developed turbulent pipes and channels, and in zero-pressure-gradient turbulent boundary layers has come into question in recent years. This is in contrast to the traditionally accepted view that, upon appropriate normalization, all three flows can be regarded as the same in the near-wall region. In this paper, the authors aim to provide clarification of this issue through streamwise velocity measurements in these three flows with carefully matched Reynolds number and measurement resolution. Results show that mean statistics in the near-wall region collapse well. However, the premultiplied energy spectra of streamwise velocity fluctuations show marked structural differences that cannot be explained by scaling arguments. It is concluded that, while similarities exist at these Reynolds numbers, one should exercise caution when drawing comparisons between the three shear flows, even near the wall.
A generalized Osborn–Cox relation
Authors: EDEN CARSTEN , OLBERS DIRK , GREATBATCH RICHARD J.
Published: July 2009

The generalized temporal residual mean (TRM-G) framework is reviewed and illustrated using a numerical simulation of vertical shear instability. It is shown how TRM-G reveals the physically relevant amount of diapycnal eddy fluxes and implied diapycnal mixing, and how TRM-G relates to the Osborn–Cox relation, which is often used to obtain observational estimates of the diapycnal diffusivity. An exact expression for the diapycnal diffusivity in the TRM-G is given in the presence of molecular diffusion, based on acknowledging and summing up an entire hierarchy of eddy buoyancy moments. In this revised form of the Osborn–Cox relation, diapycnal diffusivity is related only to irreversible mixing of buoyancy, since all advective and molecular flux terms are converted to dissipation of variance and higher order moments. An approximate but closed analytical expression can be given for the revised Osborn–Cox relation with the caveat that this closed expression implies unphysical cross-boundary rotational fluxes.

It is demonstrated that the original Osborn–Cox relation, in which advective and molecular flux terms are simply neglected, is an approximation to the full form valid to first order. In the numerical simulation the original Osborn–Cox relation holds to a surprisingly good approximation despite large advective fluxes of variance and large lateral inhomogeneity in the turbulent mixing.
Present and future schistosomiasis control activities with support from the Schistosomiasis Control Initiative in West Africa
Authors: GARBA A. , TOURÉ S. , DEMBELÉ R. , BOISIER P. , TOHON Z. , BOSQUÉ-OLIVA E. , KOUKOUNARI A. , FENWICK A.
Published: July 2009

Since 2004 the West African countries of Burkina Faso, Mali and Niger have implemented national schistosomiasis and soil-transmitted helminthiasis control programmes with financial and technical support from the Schistosomiasis Control Initiative (SCI). In the first three years of the control programmes, nearly 13·5 million doses of praziquantel and albendazole have been administered against schistosomiasis and soil-transmitted helminthiasis with coverage rates varying between 67·0% and 93·9%. These treatments have resulted in a reduction of the prevalence and intensity of Schistosoma infection in the sentinel cohorts that were set up to monitor and evaluate the national control programmes. The challenges currently faced by these national control programmes are the ability to maintain the reduction in morbidity achieved thus far due to the mass treatment campaigns and ensuring sustainability. For reinforcement of surveillance, the establishment of a geographical information system is suggested in order to contribute towards enhanced sustainability of these programmes. Our new working hypothesis is that targeted control accompanied by periodic mass treatment campaigns (every two to three years) can contribute to maintaining the low levels of morbidity achieved thus far. The implementation of integrated neglected tropical disease control programmes in these countries will provide means to ensure the financial sustainability of control activities for the years to come.
The Schistosomiasis Control Initiative (SCI): rationale, development and implementation from 2002–2008
Authors: FENWICK A. , WEBSTER J. P. , BOSQUE-OLIVA E. , BLAIR L. , FLEMING F. M. , ZHANG Y. , GARBA A. , STOTHARD J. R. , GABRIELLI A. F. , CLEMENTS A. C. A. , KABATEREINE N. B. , TOURE S. , DEMBELE R. , NYANDINDI U. , MWANSA J. , KOUKOUNARI A.
Published: July 2009

Schistosomiasis remains one of the most prevalent parasitic diseases in developing countries. After malaria, schistosomiasis is the most important tropical disease in terms of human morbidity with significant economic and public health consequences. Although schistosomiasis has recently attracted increased focus and funding for control, it has been estimated that less than 20% of the funding needed to control the disease in Africa is currently available. In this article the following issues are discussed: the rationale, development and objectives of the Schistosomiasis Control Initiative (SCI)-supported programmes; the management approaches followed to achieve implementation by each country; mapping, monitoring and evaluation activities with quantifiable impact of control programmes; monitoring for any potential drug resistance; and finally exit strategies within each country. The results have demonstrated that morbidity due to schistosomiasis has been reduced by the control programmes. While challenges remain, the case for the control of schistosomiasis has been strengthened by research by SCI teams and the principle that a national programme using ‘preventive chemotherapy’ can be successfully implemented in sub-Saharan Africa, whenever the resources are available. SCI and partners are now actively striving to raise further funds to expand the coverage of integrated control of neglected tropical diseases (NTDs) in sub-Saharan Africa.
Subcellular localization ofTrypanosoma cruziarginine kinase
Authors: MIRANDA MARIANA R. , BOUVIER LEÓN A. , CANEPA GASPAR E. , PEREIRA CLAUDIO A.
Published: July 2009

Phosphoarginine is a cell energy buffer molecule synthesized by the enzyme arginine kinase. InTrypanosoma cruzi, the aetiological agent of Chagas' disease, 2 different isoforms were identified by data mining, but only 1 was expressed during the parasite life cycle. The digitonin extraction pattern of arginine kinase differed from those obtained for reservosomes, glycosomes and mitochondrial markers, and similar to the cytosolic marker. Immunofluorescence analysis revealed that although arginine kinase is localized mainly in unknown punctuated structures and also in the cytosol, it did not co-localize with any of the subcelular markers. This punctuated pattern has previously been observed in many cytosolic proteins of trypanosomatids. The knowledge of the subcellular localization of phosphagen kinases is a crucial issue to understand their physiological role in protozoan parasites.
The involvement of TLR2 in cytokine and reactive oxygen species (ROS) production by PBMCs in response toLeishmania majorphosphoglycans (PGs)
Authors: KAVOOSI G. , ARDESTANI S. K. , KARIMINIA A.
Published: July 2009

In the present study, we show for the first time that lipophosphoglycan (LPG) stimulated cytokine production by human peripheral blood mononuclear cells is also mediated via Toll-like receptor (TLR2). In addition, in order to verify if TLR2 is involved in recognition of the purified PGs, neutralizing mAbs against TLR2 and TLR4 were used to treat the cells before being stimulated with PGs. We found strong Th1-promoting cytokines induced by sLPG but not by mLPG which was blocked by presence of anti-TLR2 mAb. This finding reveals a mechanism by which the first encounter and recognition ofL. majorpromastigotes by mLPG after interaction with TLR2 provides a cytokine milieu for consequent Th2 differentiation. Moreover, having shown the strong induction of Th1-promoting cytokines and low production of IL-10 in response to sLPG might have vaccine implication since it is recognized by TLR2 providing signals to professional antigen presenting cells that reside in the skin to promote effective T cell responses againstLeishmaniainfection. In addition, it was shown that purified mLPG and sLPG activate reactive oxygen species (ROS) production which is also blocked by anti-TLR2 but not by anti-TLR4. However, no inhibition was seen in PPG-induced cytokine and ROS production in the presence of anti-TLR2 and anti-TLR4, implying involvement of other receptors.
What if God commanded something terrible? A worry for divine-command meta-ethics
Authors: MORRISTON WES
Published: July 2009

If God commanded something that was obviously evil, would we have a moral obligation to do it? I critically examine three radically different approaches divine-command theorists may take to the problem posed by this question: (1) reject the possibility of such a command by appealing to God's essential goodness; (2) avoid the implication that we should obey such a command by modifying the divine-command theory; and (3) accept the implication that we should obey such a command by appealing to divine transcendence and mystery. I show that each approach faces significant challenges, and that none is completely satisfying.
The free-will defence: evil and the moral value of free will
Authors: HIMMA KENNETH EINAR
Published: July 2009

One version of the free-will argument relies on the claim that, other things being equal, a world in which free beings exist is morally preferable to a world in which free beings do not exist (the ‘value thesis’). I argue that this version of the free-will argument cannot support a theodicy that should alleviate the doubts about God's existence to which the problems of evil give rise. In particular, I argue that the value thesis has no foundation in common intuitions about morality. Without some sort of intuitive support, the value thesis lacks the resources to serve as the foundation for a theodicy that addresses the powerful intuition, which affects believers and non-believers alike, that a perfect God would not allow so much evil.
God, fatalism, and temporal ontology
Authors: JOHNSON DAVID KYLE
Published: July 2009

Theological incompatibility argumentssuggest God's comprehensive foreknowledge is incompatible with human free will.Logical incompatibility argumentssuggest a complete set of truths about the future is logically incompatible with human free will. Of the two, most think theological incompatibility is the more severe problem; but hardly anyone thinks either kind of argument presents a real threat to free will. I will argue, however, that sound theological and logical incompatibility arguments exist and that, in fact, logical incompatibly is the more severe problem. A deep analysis of the arguments will reveal that, to avoid a fatalist conclusion, we must reject bivalence and adopt a specific kind of temporal ontology (presentism), which also forces the theist to embrace open theism.
Pruss's ontological arguments
Authors: OPPY GRAHAM
Published: July 2009

First, I suggest that it is possible to make some further improvements upon the Gödelian ontological arguments that Pruss develops. Then, I argue that it is possible to parody Pruss's Gödelian ontological arguments in a way that shows that they make no contribution towards ‘lowering the probability of atheism and raising the probability of theism’. I conclude with some remarks about ways in which the arguments of this paper can be extended to apply to the whole family of Gödelian ontological arguments.
Orthographic influences, vocabulary development, and phonological awareness in deaf children who use cochlear implants
Authors: JAMES DEBORAH , RAJPUT KAUKAB , BRINTON JULIE , GOSWAMI USHA
Published: July 2009

In the current study, we explore the influence of orthographic knowledge on phonological awareness in children with cochlear implants and compare developmental associations to those found for hearing children matched for word reading level or chronological age. We show an influence of orthographic knowledge on syllable and phoneme awareness in deaf and hearing children, but no orthographic effect on rhyme awareness. Nonorthographic rhyme awareness was a significant predictor of reading outcomes for all groups. However, whereas receptive vocabulary knowledge was the most important predictor of word reading variance in the cochlear implant group, rhyme awareness was the only important predictor of word reading variance in the reading level matched hearing group. Both vocabulary and rhyme awareness were equally important in predicting reading in the chronological age-matched hearing group. The data suggest that both deaf and hearing children are influenced by orthography when making phonological judgments, and that phonological awareness and vocabulary are both important for reading development.
Grain size in script and teaching: Literacy acquisition in Ge'ez and Latin
Authors: ASFAHA YONAS MESFUN , KURVERS JEANNE , KROON SJAAK
Published: July 2009

The study investigated reading in four African languages that use either syllabic Ge'ez (Tigrinya and Tigre languages) or alphabetic Latin scripts (Kunama and Saho). A sample of 385 Grade 1 children were given letter knowledge, word reading, and spelling tasks to investigate differences at the script and language levels. Results showed that the syllable based Ge'ez script was easier to learn than the phoneme-based Latin despite the bigger number of basic units in Ge'ez. Moreover, the syllable based teaching of alphabetic Saho produced better results than alphabetic teaching of Kunama. These findings are discussed using the psycholinguistic grain size theory. The outcomes confirm the importance of the availability of phonological units in learning to read.
Against Parsimony: Three Easy Ways of Complicating some Categories of Economic Discourse
Authors: Hirschman Albert O.
Published: July 2009

Economics as a science of human behavior has been grounded in a remarkably parsimonious postulate: that of the self-interested, isolated individual who chooses freely and rationally between alternative courses of action after computing their prospective costs and benefits. In recent decades, a group of economists has shown considerable industry and ingenuity in applying this way of interpreting the social world to a series of ostensibly noneconomic phenomena, from crime to the family, and from collective action to democracy. The “economic” or “rational-actor” approach has yielded some important insights, but its onward sweep has also revealed some of its intrinsic weaknesses. As a result, it has become possible to mount a critique which, ironically, can be carried all the way back to the heartland of the would-be conquering discipline. That the economic approach presents us with too simpleminded an account of even such fundamental economic processes as consumption and production is the basic thesis of the present paper.
The Emperor's Newest Clothes
Authors: Hollis Martin
Published: July 2009

There is a simple joy in finding that the emperor has positively no clothes and especially when the finger is pointed in ribald good English. Donald McCloskey does this service in “The Rhetoric of Economics”, where he argues with force and wit that “modernism” (meaning, roughly, positivism, as in “Positive Economics”) will do as an account neither of what economists do nor of what it makes philosophical sense for them to attempt. Instead they should recognize that models are always metaphors and should make a virtue of the literary devices, which they in fact rely on. Armed with the craft of rhetoric and a new “poetics of economics,” they will achieve better writing, better teaching, better foreign relations, better science and better dispositions.
Rosenberg's “Lakatosian Consolations for Economists”: Comment
Authors: Weintraub E. Roy
Published: July 2009

Rosenberg (1986) argues that economists have embraced the methodology of scientific research programs, and the writings of Imre Lakatos (1978), at the same time that philosophers have been abandoning that approach. According to Rosenberg, the methodology of scientific research programs (MSRP) appears to allow some work in economics, which is neither tested nor testable, to be “scientific” nonetheless. That is, MSRP justifies some current practices which look hard to justify on strict falsificationist, or dogmatic positivist, grounds.
Is Economics Empirical Knowledge?
Authors: Rappaport Steven
Published: July 2009

Alexander Rosenberg has played a large role in creating the philosophy of economics as a distinct area of philosophy. But since the publication of Microeconomic Laws in 1976, Professor Rosenberg's thinking about economics has been casting the subject in an increasingly uncomplimentary light. This development is reflected in Rosenberg's new book Economics–Mathematical Politics or Science of Diminishing Returns? In this stimulating work Rosenberg endorses the view that economics does not constitute scientific empirical knowledge. He says:
On the Foundations of Nash Equilibrium
Authors: Jørgen Jacobsen Hans
Published: July 2009

The most important analytical tool in non-cooperative game theory is the concept of a Nash equilibrium, which is a collection of possibly mixed strategies, one for each player, with the property that each player's strategy is a best reply to the strategies of the other players. If we do not go into normative game theory, which concerns itself with therecommendationof strategies, and focus instead entirely on the positive theory ofprediction, two alternative interpretations of the Nash equilibrium concept are predominantly available.

In the more traditional one, a Nash equilibrium is a prediction ofactual play. A game may not have a Nash equilibrium in pure strategies, and a mixed strategy equilibrium may be difficult to incorporate into this interpretation if it involves the idea of actual randomization over equally good pure strategies. In another interpretation originating from Harsanyi (1973a), see also Rubinstein (1991), and Aumann and Brandenburger (1991), a Nash equilibrium is a ‘consistent’ collection of probabilistic expectations,conjectures, on the players. It is consistent in the sense that for each player each pure strategy, which has positive probability according to the conjecture about that player, is indeed a best reply to the conjectures about others.
Identification and Economic Behavior Sympathy and Empathy in Historical Perspective
Authors: Fontaine Philippe
Published: July 2009

In modern economics, the use of sympathy and empathy shows significant ambiguity. Sympathy has been used in two different senses. First, it refers to cases where the concern for others directly affects an individual's own welfare (Sen, 1977). Second, the term has served the purposes of welfare economics, where it is associated with interpersonal comparisons of the extended sympathy type, that is, comparisons between one's own situation in a social state and someone else's in a different social state (Arrow, 1963 [1951]). On the other hand, empathy has been used interchangeably with sympathy either to render the idea of interdependent utility functions (Leibenstein, 1976), or to convey the imaginative process of imagining oneself in someone else's place (Harsanyi, 1977).
Reliabilities of Consecutive-2 Graphs
Authors: Du D.Z. , Hwang F. K.
Published: July 2009

A consecutive-2 graph is a graph where each vertex is associated with a failure probability and the graph is considered failed if any two adjacent vertices both fail. Recently, the problem of computing reliability for general consecutive-2 graph was shown to be #P-complete while polynomial algorithms exist for trees. In this paper, we give a linear time algorithm for a class of graphs including forests and cycles.

For a given set of failure probabilities qi, the assignment of qi to the vertices of a given graph is optimal if it maximizes the reliability of that graph. It is known that optimal assignments for trees require messy computations while linear algorithms exist for lines and stars. In this paper, we prove that the optimal reliability of any n−tree is bounded between those of an n−line and an n−star.
The Throughput Rate of Multistation Production Lines with Stochastic Servers
Authors: Alkaff Abdullah , Muth Eginhard J.
Published: July 2009

A serial production line with an arbitrary number of stations is analyzed using the holding-time model. In contrast to Markovian state models, the holding-time model does not require the service times to be exponentially distributed. The distribution of the interdemand time at the first station is obtained as a function of the distribution of station service times which are of a general nature. The throughput rate of the line is the reciprocal of the mean interdemand time. For service times of phase type, two numerical solution methods, one exact and the other approximate, are presented. Numerical results are given for up to ten stations.
Asymptotic Results for Buffer Systems under Heavy Load
Authors: Ommeren J. C. W. Van , Kok A. G. de
Published: July 2009

This paper considers a dam (or storage) model of the GI/G/I type with a finite capacity K. An arriving input being larger than the unfilled capacity of the dam causes an overflow where the excess amount is lost. Important performance measures for this system are the overflow probability and the long-run fraction of input that is lost. We give asymptotic expansions for these measures for large K both for the case of a load factor less than 1 and for the case of a load factor larger than 1. Also, related results are obtained for the impatient customer model of the M/G/l type.
The Pricing Problem
Authors: Reeves Jaxk H. , Mallik Ashim , McCormick William P.
Published: July 2009

A sequential procedure to select optimal prices based on maximum likelihood estimation is considered. Asymptotic properties of the pricing scheme and the concommitant estimation problem are examined. For small sample sizes, simulation results show that the proposed procedure has high efficiency relative to the best procedure when the parameter is known.
Conditional Belief Structures
Authors: Kohlas Jürg
Published: July 2009

The mathematical theory of evidence (Shafer et al. [9]) has recently found much interest as an approach to treat uncertainty in expert and knowledge-based systems. Although the theory is very promising, there are not yet many practical applications. Modeling practice has still to be developed. This is a crucial task in view of facilitating the application of evidential modeling. It is the aim of this paper to discuss an important element of evidential modeling–conditional belief–within the scope of the mathematical theory of evidence.
Modeling Power of Stochastic Petri Nets for Simulation
Authors: Haas Peter J. , Shedler Gerald S.
Published: July 2009

Generalized semi-Markov processes and stochastic Petri nets have been proposed as general frameworks for a discrete event simulation on a countable state space. The two formal systems differ, however, with respect to the clock setting (event scheduling) mechanism, the state transition mechanism, and the form of the state space. We obtain conditions under which the marking process of a stochastic Petri net “mimics” a generalized semi-Markov process in the sense that the two processes (and their underlying general state-space Markov chains) have the same finite dimensional distributions. The results imply that stochastic Petri nets have at least the modeling power of generalized semiMarkov processes for discrete event simulation.
Computational Complexity of Coherent Systems and the Reliability Polynomial
Authors: Barlow R.E. , Iyer S.
Published: July 2009

There are three general methods for system reliability evaluation, namely; (1) inclusion–exclusion, (2) sum of disjoint products, and (3) pivoting. Of these, only pivoting can be applied directly to a logic tree or network graph representation without first finding minimal path (or cut) sets. Domination theory provides the basis for selecting optimal pivoting strategies. Simple proofs of domination-theory results for coherent systems are given, based on the reliability polynomial. These results are related to the problem of finding efficient strategies for computing coherent system reliability. The original results for undirected networks are due to Satyanarayana and Chang [5] (cf. [1]). Many of the original set theoretic results are due to Huseby [3]. However, he does not use the reliability polynomial to prove his results.
A Note on Error Bounds for Approximating Transition Probabilities in Continuous-time Markov Chains
Authors: Dijk Nico M. van
Published: July 2009

Recently, Ross [1] proposed an elegant method of approximating transition probabilities and mean occupation times in continuous-time Markov chains based upon recursively inspecting the process at exponential times. The method turned out to be amazingly efficient for the examples investigated. However, no formal rough error bound was provided. Any error bound even though robust is of practical interest in engineering (e.g., for determining truncation criteria or setting up an experiment). This note primarily aims to show that by a simple and standard comparison relation a rough error bound of the method is secured. Also, some alternative approximations are inspected.
The Demand for Information and the Distribution of Income
Authors: Arrow Kenneth J.
Published: July 2009

Investors can increase their payoff by acquiring information on rates of return. The value of the information is greater, the greater the amount to be invested. Therefore, information purchased and consequently the expected rate of return increases with initial wealth, and the distribution of final wealth is more unequal than that of initial wealth.