bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rutile and titanium particles differentially affect the production of osteoblastic local factors
Authors: Vallés Gema , González‐Melendi Pablo , Saldaña Laura , Rodriguez Mercedes , Munuera Luis , Vilaboa Nuria 
Published: July 2007

AbstractTitanium and its alloys are widely used as implant materials for dental and orthopaedic applications. To improve their wear and corrosion resistance, several surface modifications that give rise to an outer ceramic layer of rutile have been developed. It is expected that after a long period of functional loading, rutile debris will arise from these modified surfaces. We have compared the in vitro biocompatibility of subcytotoxic doses of rutile and titanium particles of phagocytosable size in primary cultures of human osteoblasts. Particles were visualized using a spectral confocal microscope by reflection. Both types of particles aggregated in the culture media and were efficiently internalized by osteoblasts as agglomerates. Treatment of isolated cultures of osteoblasts with rutile particles stimulated the release of IL‐6, PGE2, and GM‐CSF to a lesser extent than titanium. The influence of macrophages on the particle‐induced stimulation of those local factors was analyzed by coculturing TPA‐differentiated THP‐1 cells with osteoblasts. Under these conditions, levels of IL‐6 and PGE2 after treatment of cocultured osteoblasts with rutile particles were lower than after exposure to titanium. These results indicate that rutile debris shows a lower bioreactivity than titanium when tested in cultures of human osteoblasts and support the improved biocompatibility of titanium‐based implants modified to create an outer layer of rutile on their surfaces. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Enamel matrix derivative protects human gingival fibroblasts from TNF‐induced apoptosis by inhibiting caspase activation
Authors: Zeldich E. , Koren R. , Dard M. , Nemcovsky C. , Weinreb M. 
Published: July 2007

AbstractEmdogain®, a formulation of enamel matrix derivative (EMD), is used clinically for regeneration of the periodontium (tooth supporting tissues), but the molecular mechanisms of its action have not been elucidated. Several clinical studies suggested that EMD may also improve gingival healing after periodontal surgery and thus affect the fate of gingival fibroblasts (GFs). Since these cells are targets for local inflammatory mediators such as TNF, a pro‐apoptotic cytokine, during the course of periodontal disease, we tested whether EMD protects human GFs (hGFs) from TNF‐induced cytotoxicity. Quiescent primary hGFs were challenged with TNF (10–100 ng/ml) with or without EMD (100 µg/ml) pretreatment. Cell viability was assessed by neutral red staining, cell death by LDH release and apoptosis by caspase activity. Signaling pathways were evaluated by Western blotting and pharmacological inhibitors. TNF induced classical signs of apoptosis in hGFs, including typical cellular morphology and increased caspase activity. TNF‐induced cytotoxicity was entirely caspase‐dependent. Pretreatment (4–24 h) with EMD dramatically inhibited the activation of initiator and executioner caspases and enhanced hGF survival. Although TNF induced the activation of p38 MAPK, JNK, ERK and PI‐3K signaling, these pathways were not crucial for EMD protection of hGFs. However, EMD increased the levels of c‐FLIPL, an anti‐apoptotic protein located upstream of caspase activation. These data demonstrate, for the first time, that EMD protects hGFs from inflammatory cytokines and, together with our recent reports that EMD stimulates rat and human GF proliferation, could help explain the mechanisms whereby in vivo use of EMD promotes gingival healing. J. Cell. Physiol. 213:750–758. © 2007 Wiley‐Liss, Inc.
Comparison of affinity membrane adsorbers for the purification of recombinant human erythropoietin (rhEPO)
Authors: Mellado Maria Candida M , Curbelo David , Nobrega Ronaldo , Castilho Leda R 
Published: July 2007

AbstractIn this work affinity membrane adsorbers were investigated for the chromatographic purification of recombinant human erythropoietin (rhEPO) produced in mammalian cells. Cibacron Blue (CB), IDA‐Cu+2, wheat germ agglutinin (WGA), concanavalin A (ConA) and an anti‐EPO monoclonal antibody (MAb) were tested as affinity ligands, attached to microporous Sartobind® membranes. In experiments carried out with cell culture supernatant, the best results were obtained with Sartobind–CB, Sartobind–WGA and Sartobind–MAb membranes. The thermodynamic parameters were determined by adsorption isotherms of rhEPO onto the membranes. Sartobind–ConA presented the lowest affinity for rhEPO, as evidenced by a lower association constant. For Sartobind–CB, Sartobind–IDA‐Cu+2 and Sartobind–MAb KA was in the order of 105 L mol−1, whereas for Sartobind–WGA it was 106 L mol−1. Sartobind–CB eluates were also investigated by RP‐HPLC. The purity level achieved in this one‐step purification strategy was 55%, indicating that the Sartobind–CB membrane is a promising affinity membrane for rhEPO purification. Copyright © 2007 Society of Chemical Industry
Chiral discrimination of α‐amino acids by the DNA triplet GCA using amino acids as a co‐selector
Authors: Kumar Maddula Ravi , Prabhakar Sripadi , Sivaleela Tallagadda , Vairamani Mariappanadar 
Published: July 2007

AbstractThe DNA triplet GCA is successfully used as a chiral selector for the chiral discrimination of amino acids using amino acids themselves as a co‐selector. Chiral discrimination was achieved by investigating the collision‐induced dissociation spectra of the [XA + XR + 2Y − 2H]2− ion generated by electrospraying a mixture of analyte amino acid (XA), reference amino acid (XR) and GCA (Y). The relative abundances of fragment ions resulting from the competitive loss of reference and XA's are considered for measuring the degree of chiral discrimination. GCA successfully shows D‐selectivity for all the amino acids, except Tyr and Lys. The success of the method lies in the selection of a suitable 10R that has closer GCA binding affinity to that of analyte. The degree of discrimination by GCA is improved in the presence of the reference, and the chirality of the reference does not change the selectivity of GCA. The suitability of the method for the measurement of optical purity is also demonstrated. Copyright © 2007 John Wiley & Sons, Ltd.
Thermal processing enhances anti‐radical activity and reduces pro‐oxidant activity in water‐soluble fraction of selected Allium vegetables
Authors: Roy Molay Kumar , Takenaka Makiko , Isobe Seiichiro 
Published: July 2007

AbstractBoth the pro‐ and antioxidant activities were found in water‐soluble components contained in onion, leek and garlic samples, and effects of thermal treatment on such activities were investigated. Raw vegetable extracts were prepared by squeezing vegetable homogenates followed by centrifugation at 4 °C. The extracts were subjected to thermal treatment at 75 or 100 °C for 30 and 60 min. The water‐soluble extracts were assayed for antiradical activity using both a chemical and a cellular system. Heating onion and leek extracts at 100 °C for 60 min, and garlic extract at 100 °C for 30 min, yielded strong antioxidant components that are able to scavenge free radicals, in either system, significantly. Measuring total phenolic content by the Folin–Ciocalteu method, we observed that thermal treatment significantly decreased the phenolic contents in leek and garlic extract. In addition, we estimated pro‐oxidant activities in the vegetable extracts, using reactive oxygen species (ROS)‐sensitive 2′,7′‐dichlorofluorescin diacetate; we found that extracts of raw alliums have strong ROS activity, and that thermal treatment destroyed most of the ROS activity present in the raw extracts. These findings indicate that thermal processing enhanced the nutritional value of alliums by increasing the total antioxidant activity, and reducing the pro‐oxidant elements. Copyright © 2007 Society of Chemical Industry
Soil classification and salinity mapping for determining restoration potential of cropped riparian areas
Authors: Amezketa E. , de Lersundi J. Del Valle 
Published: July 2007

AbstractRestoration and management of riparian areas have recently become important issues. Soil and salinity surveys are required before planning restoration activities and land‐uses if the riparian area is salt‐affected. In this study, we characterise the soils and salinity conditions of a riparian area that underwent irrigated agriculture with significant soil salinisation, to assess the general site suitability for riparian restoration and potential land‐uses. Throughout the area, 19 profiles were described and classified and 95 soil samples were collected for their chemical and physical characterisation. The salinity of the 35‐ha presumably salt‐affected area was analysed by reading the bulk soil electrical conductivity (ECa) with the hand‐held electromagnetic‐induction sensor Geonics‐EM38 at 558 locations and by measuring the electrical conductivity of the saturation extract (ECe) and sodium adsorption ratio (SAR) of 60 soil samples collected at 30 of those locations. The regression of ECe on EM readings predicted ECe with R2 > 0·92 at the 0–100 cm soil depth. The geo‐referenced soil classification (three soil units were established) and salinity maps identified the soil constraints for the area's restoration potential. The major limiting soil factors were soil salinity, sodicity and waterlogging in the southern half of the soil unit #3, and soil compaction in most of the area. The value of those limiting factors, along with differences in soil texture, as a means of assessing restoration potential of riparian vegetation and for identifying suitable land‐uses for the three soil units was discussed. Agro‐forestry, planned grazing, recreational and educational land‐uses are possible for the site. Copyright © 2007 John Wiley & Sons, Ltd.
Group classification of one‐dimensional equations of fluids with internal inertia
Authors: Hematulin Apichai , Meleshko Sergey V. , Gavrilyuk Sergey L. 
Published: July 2007

AbstractOne‐dimensional flows of fluids with internal inertia are studied in the manuscript. The given equations include such models as the non‐linear one‐velocity model of a bubbly fluid (with incompressible liquid phase) at small volume concentration of gas bubbles (Zh. Prikl. Tekh. Fiz. 1960; N3:102–111, Dokl. AN USSR 1961; 137:1331–1333, J. Fluid Mech. 1968; 33:465–474), and the dispersive shallow water model (J. Fluid Mech. 1976; 78:237–246, Lectures on Geophysical Fluid Dynamics. Oxford University Press: New York, 1998). These models are obtained for special types of the function $W(\rho,\,\dot{\rho})$. The group classification separates these models in 10 different classes. Optimal systems of subalgebras are constructed for all models. The knowledge of optimal systems of admitted subalgebras allows constructing essentially different invariant solutions. Copyright © 2007 John Wiley & Sons, Ltd.
Soy isoflavones and fatty acids: Effects on bone tissue postovariectomy in mice
Authors: Ward Wendy E. , Fonseca Debbie 
Published: July 2007

AbstractOsteoporosis is a silent disease that leads to fragility fractures that can diminish quality of life and contribute to death. With no ideal drug treatment available to manage osteoporosis, soy isoflavones (ISO), and omega‐3 long chain PUFAs in fish oil (FO) may be integral in a dietary strategy that prevents bone loss. The overall objective of this study was to determine if combining ISO with omega‐3 long chain PUFAs resulted in greater protection against the loss of bone mineral and skeletal weakening in ovariectomized mice. Ovariectomized CD‐1 mice were randomized to control diet or a diet containing ISO alone (250 mg of genistein + 250 mg of daidzein/kg diet), FO alone (7% menhaden oil), or ISO + FO. Each dietary intervention prevented the loss of bone mineral density (BMD) in the femur and preserved femur strength, but only FO, either alone or combined with ISO, resulted in a higher BMD of lumbar vertebra (LV). Most notably, FO + ISO resulted in a higher peak load of LV4, indicating that vertebra were more resistant to fracture. Whether a dietary strategy providing FO in combination with ISO attenuates bone loss in postmenopausal women awaits investigation.
Optimal operations in non‐linear water networks
Authors: Coulbeck B. 
Published: July 2007

AbstractThe paper introduces the practical problems associated with automated control of large‐scale non‐linear water networks and gives the additional theoretical requirements for optimizing the network operation. A control scheme is presented which is intended for computer controlled operations and hence requires on‐line evaluation of optimal control strategies based on a simulation of the overall dynamics of the network. Realistic applications of the scheme are shown to depend on adequate simplifications of the network performance, and results are given for development of linear dynamic models together with cost criteria in linear or quadratic form. Use of a hierarchical optimization technique permits a solution to be obtained to the remaining problems of high dimensionality with constrained variables. Application of the method to a complex network leads to results which are consistent with normal operational experience and which give minimized overall costs.
Application of an advanced trajectory optimization method to ramjet propelled missiles
Authors: Paris S. W. , Joosten B. K. , Fink L. E. 
Published: July 2007

AbstractThe mission performance characteristics of ramjet‐propelled missiles are highly dependent upon the trajectory flown. Integration of the trajectory profile with the ramjet propulsion system performance characteristics to achieve optimal missile performance is very complex. Past trajectory optimization methods have been extremely problem dependent and require a high degree of familiarity to achieve success. A general computer code (CTOP) has been applied to ramjet‐powered missiles to compute open‐loop optimal trajectories. CTOP employs Chebyshev polynomial representations of the states and controls. This allows a transformation of the continuous optimal control problem to one of parameter optimization. With this method, the trajectory boundary conditions are always satisfied. State dynamics and path constraints are enforced via penalty functions. The presented results include solutions to minimum fuel‐to‐climb, minimumtime‐to‐climb, and minimum time‐to‐target intercept problems.
Experimental evaluation of adaptive identifiers
Authors: Neuman C. P. , Baradello C. S. 
Published: July 2007

AbstractTransient response and tracking characteristics of three adaptive identifiers are illustrated and compared experimentally through digital simulation. Focus is placed on series‐parallel (SP) identifiers, with and without auxiliary error signals. The identifiers are algorithms which have adjustable coefficients and are designed to follow the process output. At each computational cycle, the coefficients of the identifier (and the error signals) are updated in response to the tracking error between the process and identifier outputs. The process is simulated on an EAI TR‐20 analogue computer, and the identification algorithms are implemented on a PDP‐11/40 minicomputer. Testing is distributed over three processes commonly encountered by the control engineer. Variable adaptation gains, which are positive functions of the absolute value of the tracking error, accelerate the convergence of the identifiers. The experimental results are summarized in terms of the computational requirements of the identifiers.
An optimal control problem with piecewise quadratic cost functional containing a ‘dead‐zone’
Authors: Parlar Mahmut , Vickson R. G. 
Published: July 2007

AbstractIn this paper, we describe an exact solution method for the problem of optimally controlling a deterministic discrete linear system with piecewise quadratic cost functional containing a ‘dead‐zone’. This model generalizes the well‐known optimal control model for a linear system with (symmetric) quadratic objective functional. This more general problem is solved by using concepts and techniques from the theory of nonlinear programming, for example Kuhn‐Tucker theory, duality, linear complementarity, and Lemke's algorithm. We apply the results to the solution of a 25‐period deterministic pension funding problem which is modelled as a discrete‐time optimal control problem. The controls for this problem are company contributions and investment amounts, and the state is the value of the pension fund.
Optimal open‐loop control of the mould filling process for injection moulding machines
Authors: Cho Y. J. , Cho H. S. , Lee C. O. 
Published: July 2007

AbstractProduct quality of injection‐moulded' plastics greatly depends upon the injection flow rate of molten polymer during filling. In this paper, an optimal control of the filling process is shown to improve the properties of the moulded parts. Our goal is to provide an efficient basis for designing a supervisory computer‐controlled injection moulding system. A dynamic model of the filling process is developed. It takes into account the effect of molten polymer on the dynamics of the injection ram. Based upon this model, an optimal control input, which is a control current actuating the injection ram‐screw assembly, is derived from the minimization of a quadratic performance index which serves to keep the front velocity of molten polymer flow into the cavity at a desired value. The optimal input thus obtained has been implemented via a microcomputer for on‐line control of the injection process. The experimental results show that surface blemish and residual stress of the moulded parts can be reduced via this optimal control.
A formal theory of lobbying behaviour
Authors: Reinganum Jennifer F. 
Published: July 2007

AbstractThis paper analyses strategic lobbying behaviour under the assumption of disorganized opposition. A dynamic programming approach is used. The optimal rate of lobbying expenditure is shown to be an increasing function of time. A specific example is computed to determine the influence of various parameters. Next, the case of lobbying against an active counterlobby is considered in a dynamic game‐theoretic framework. The Nash equilibrium rates of lobbying expenditure are computed for a specific example with symmetric players. The equilibrium rates of expenditure for the two lobbyists may be either everywhere increasing, everywhere decreasing, or single peaked as a function of time. In addition, some comparative statics results are reversed relative to those of the disorganized opposition model.
On the solution of the linear‐quadratic optimal control problem by extended invariant imbedding
Authors: Breitenecker Felix 
Published: July 2007

AbstractThe solution of the linear‐quadratic output regulator problem by Pontryagin's maximum principle results in an unstable linear boundary value problem. The method of invariant imbedding, which requires the integration of a matrix Riccati differential equation, solves certain boundary value problems in a stable manner. In order to make this well known method applicable, an extension algorithm is defined, which maps the boundary value problem into a problem of double dimension. The resulting algorithm of extended invariant imbedding does not depend on the boundary values. So the matrix Riccati equation has to be integrated only once ‘offline’: The unknown boundary values, the state, and the control are calculated by solution of systems of linear equations (‘online’). So, if the boundary values change, only systems of linear equations have to be solved once more. The algorithm has two variants with usually contrary stability behaviour.
Minimum energy control of time‐delay systems via walsh functions
Authors: Palanisamy K. R. , Rao Ganti Prasada 
Published: July 2007

AbstractThis paper presents a Walsh function approach to the minimum energy control of linear systems with time delay satisfying given conditions on the terminal state. Walsh operational matrices for integration, delay and advance1 are employed in solving the related state and costate equations containing terms with advanced and delayed arguments. The technique of extension of the solution with a single term Walsh series2 is adapted to the case of differential equations with delay and advance terms, leading to an enormous reduction in computational effort. The results may be computed in two forms, piecewise constant or discrete, satisfying both the energy and terminal conditions.
Optimal control of a diffusion model of new product acceptance with price‐dependent total market potential
Authors: Josrgensen Steffen 
Published: July 2007

AbstractThis paper deals with the problem of finding an optimal pricing policy for the dynamics of an innovator‐imitator diffusion model of new product acceptance. Total market potential is assumed to be a linearly‐decreasing function of price, and the objective of the firm is to maximize the present value of the profit stream over an infinite horizon. By using Green's theorem, one can show that the optimal policy is to approach long‐run stationary equilibrium sales (the turnpike) as fast as possible followed by a permanent stay on the turnpike.
An active‐constraint logic for non‐linear programming
Authors: Das Alok , Cliff Eugene M. , Kelley Henry J. 
Published: July 2007

AbstractActive‐constraint logic for non‐linear programming processes is sought such that the constraints in the active set possess positive projection multipliers and the resulting step does not violate the linear approximations to any of the constraints satisfied as equalities but considered inactive. Active‐constraint logic which has the desired properties is given for the cases of two and three constraints. For the general case featuring more than three constraints satisfied as equalities, an active‐set logic is suggested. The efficiency of the proposed logic is tested computationally on some quadratic programming problems in comparison with three existing active‐set strategies.
Steering controls for constrained controllability problems with application to magnetic suspension
Authors: Van Til R. P. , Schmitendorf W. E. 
Published: July 2007

AbstractA method is presented for determining a control which steers a system to a specified target when there are magnitude constraints on the control. The method is suitable for numerical computation since it only involves solving finite‐dimensional optimization problems. The effectiveness of the technique is illustrated by applying it to the problem of suspending a ferromagnetic rotor in a magnetic field.
Multivariable linear digital control via state‐space output matching
Authors: Miller David F. 
Published: July 2007

AbstractA direct state‐space approach to the digital control of multivariable linear systems is presented. Control is provided by minimizing the mean square error between controlled plant outputs and specified desired output trajectories at sampling instants. Linear equations for digital control inputs are solved in constant forward and feedback gain form. Numerical applications to problems in simple model following, digital redesign and direct digital design are given.
Optimal manpower policies in a dynamic staff‐maximizing bureau
Authors: Hartl Richard F. , Jørgensen Steffen 
Published: July 2007

AbstractThe dynamic problem of optimal manpower planning in a public agency is considered. The budget available to the bureau is replenished at a rate proportional to the output. The objective of the bureau manager is to maximize the staff at the terminal time. The model is non‐linear in the control, the hiring rate. Cases where a deficit is allowed are also considered. Boundary solutions are investigated for the case of no deficit, and it is shown that the hiring rate is non‐differentiable but continuous.