bluuebunny/crossref_metadata_2025 huggingface dataset:
Self‐tuning control of robot manipulators
Authors: Nicosia Salvatore , Tomei Patrizio
Published: July 2007

We consider the tracking control problem for robot manipulators whose parameters are not exactly known. It is assumed that some unmodelled friction is acting at the actuated joints. The proposed solution guarantees that the disturbances on the outputs (the joint positions) can be attenuated by an arbitrary factork. For the setpoint regulation problem a self‐tuning controller is proposed. In this case the disturbances (uncertain parameters and unmodelled non‐linearities) on the outputs are completely rejected asymptotically. Some simulation results are included.
Adaptive non‐linear speed control of induction motors
Authors: Raumer Thomas Von , Dion Jean Michel , Dugard Luc
Published: July 2007

In this paper we present two adaptive non‐linear speed control algorithms for induction motors. They employ input‐output linearization techniques for the motor model in the stator fixed reference frame. The first control algorithm directly tracks speed and rotor flux. The second is designed using torque and rotor flux tracking and is extended for speed control. A key point is that this algorithm ensures exact current limitation in the known parameter case. The adaptation based on Lyapunov design can cope with rotor and stator resistance variations. Significant simulations using sampled controllers are presented emphasizing adaptation and current limitation effects.
Adaptive performance enhancement by iterative identification and control design
Authors: Schrama Ruud J. P. , Bosgra Okko H.
Published: July 2007

In this paper we combine adaptation and robust control by an iterative scheme of system identification and control design. A nominal model is identified for robust control design and the controller is applied to the plant to gather new data for an update of the nominal model. Our objective is to improve the plant performance with every iteration right from the start. We tackle this problem with frequency domain identification and a control design method that optimizes robustness against coprime factor perturbations. Our approach is illustrated by simulated and practical examples.
Unifying the landmark developments in optimal bounding ellipsoid identification
Authors: Deller J. R. , Nayeri M. , Liu M. S.
Published: July 2007

A general class of optimal bounding elipsoid (OBE) algorithms, including all methods published to date, is unified into a single framework called theunified OBE (UOBE)algorithm. UOBE is based on generalized weighted recursive least squares in which very broad classes of ‘forgetting factors’ and data weights may be employed. Different instances of UOBE are distinguished by their weighting policies and the criteria for determining optimal weight values.

A study of existing OBE algorithms, with a particular interest in the trade‐off between algorithm performance interpretability and convergence properties, is presented. Results suggest that an interpretable, converging UOBE algorithm will be found. In this context a new UOBE technique, theset membership stochastic approximation (SM‐SA)algorithm, is introduced. SM‐SA possesses interpretable optimization measures and known conditions under which its pointestimatorconverges.
On‐line parameter interval estimation using recursive least squares
Authors: Gutman Per‐Olof
Published: July 2007

A bank of recursive least‐squares (RLS) estimators is proposed for the estimation of the uncertainty intervals of the parameters of an equation error model (or RLS model) where the equation error is assumed to lie between known upper and lower bounds. It is shown that the off‐line least‐squares method gives the maximum and minimum parameter values that could have produced the recorded input‐output sequence. By modifying the RLS estimator in two ways, it is possible to recursively compute inner and outer bounds of the uncertainty intergals. It is shown that the inner bound is asymptotically tight.
Possible bursting phenomena in self‐tuning control
Authors: Radenkovic Miloje S. , Michel Anthony N.
Published: July 2007

In this paper, in the case when there are no modelling errors, bursting phenomena in extended‐least‐squares‐ (ELS‐) based self‐tuning control are analysed. It is shown that in the absence of external excitation and without imposing structural conditions on the system model, bursts of the tracking error and consequently drift of the parameter estimates are possible. By analysing the possible occurrence of bursting, an upper bound on the convergence rate of the tracking error is established. It is demonstrated that it is the self‐excitation mechanism which provides global stability of the adaptive system. In other words, the possible instability of the adaptive loop generates a bounded condition number of the covariance matrix. This in turn implies stabilization of the adaptive system. In this paper we also discuss a stochastic gradient algorithm with a convergence rate similar to that presently established for the ELS‐based self‐tuning controller.
A direct adaptive generalized predictive control algorithm with guaranteed stability
Authors: Wang Wei
Published: July 2007

In this paper a direct version of adaptive generalized predictive control is considered. A direct adaptive generalized predictive control algorithm is suggested and stability of the closed‐loop system is proved under some assumptions. A simulation example demonstrates the effectiveness of the algorithm.
Adaptive estimation of hidden nearly completely decomposable Markov chains with applications in blind equalization
Authors: Krishnamurthy Vikram
Published: July 2007

This paper proposes maximum likelihood (ML) estimation schemes for nearly completely decomposable Markov chains (NCDMCs) in white Gaussian Noise. Aggregation techniques based on stochastic complementation are applied to significantly reduce the dimension of the resulting hidden Markov model (HMM) and hence substantially reduce the computational requirements of the estimation algorithms. Stochastic complementation results in exact aggregation in that no approximations are involved in the steady state probability distribution of the Markov chain.

We then present anoff‐lineestimation algorithm for the parameters and states of the HMM based on the estimation of the aggregated HMM. This off‐line algorithm is an ML estimation scheme and is based on the expectation maximization (EM) algorithm. It has a significantly reduced computational complexity compared with the standard (full‐order) EM‐based HMM estimation scheme.

Finally we present an application of our techniques. We show that hidden NCDMCs can be used to formulate the blind equalization problem for noisy FIR channels with Markov inputs, e.g. phase‐shiftkeyed (PSK) signals. We then propose recursive EM and gradient estimation techniques for the aggregated HMM resulting inon‐lineestimates of the channel coefficients and signal estimate.

For anNa‐state Markov chain our aggregate‐based estimation scheme has a computational complexityO(N−2a), whereas standard algorithms have a complexityO(Na−L+ 1) at each time instant, whereLis the length of the FIR channel.
Model reference adaptive control for robotic manipulators without velocity measurements
Authors: Schwartz Howard M.
Published: July 2007

This paper presents a non‐linear model reference adaptive controller for robot manipulators. Although the motivating application for this algorithm is in the field of robotics, the algorithm could be applied to non‐linear systems that are feedback‐linearizable. The algorithm developed does not require the measurement nor the estimation of manipulator joint velocities or accelerations. Simulation results verify the performance of the method.
A new adaptive LQG control algorithm
Authors: Birmiwal Kailash
Published: July 2007

A new control algorithm is developed for the discrete time, finite horizon adaptive LQG problem. In the new algorithm, randomization over linear control functions is performed at future stages to find a deterministic desired control U(k) at the current stage. This randomized linear control policy, which is U(k)‐dependent and non‐linear in measurements, incorporates explicitly the knowledge available about the unknown parameter at future stages in terms of the posterior distribution. At the same time it enables us to obtain a closed form expression of an approximation of the optimal control‐cost function. Numerical examples comparing the new solution with the optimal are also provided.
Lowa prioristatistical information model for optimal smoothing and differentiation of noisy signals
Authors: Fioretti S. , Jetto L.
Published: July 2007

A novel approach is proposed to the optimal smoothing and differentiation problem of unknown one‐dimensional signals corrupted by additive white Gaussian noise. State space techniques are used. the main feature of the method is that very littlea prioristatistical information about the signal generation process is required. Starting from the basic assumption that the actual waveform does not show relevant discontinuities, a state space representation is derived by defining a state vector composed of the signal and its derivatives. All parameters of this representation are analytically derived except two: a multiplicative scalar of the input noise covariance matrix and the variance of the measurement noise. A procedure for the optimal estimation of these parameters from noisy data is proposed. Application of a fixed‐lag Kalman smoother provides the simultaneous estimate of the signal and its derivatives. Numerical results confirm the validity of the approach.
Discontinuous pole assignment control of uncertain systems using only input/output measurements
Authors: Bartolini Giorgio , Ferrara Antonella
Published: July 2007

This paper deals with the combined use of continuous and discontinuous adaptation mechanisms in order to control uncertain linear time‐invariant systems described by I/O relationships. the complexity of the combined schemes proposed in the literature up to now relies on both the complexity of the underlying linear structure, i.e. the structure of the controller designed under the assumption of perfect knowledge of the plant parameters in order to attain the prescribed control objective, and the complexity of the additional scheme which needs to be introduced in the uncertain case so as to guarantee the stability of the relevant error equation as well as the convergence of the adjusted parameters. In the present paper it is shown how, by choosing a pole assignment control objective, it is possible to conceive a new combined variable structure‐adaptive control scheme which on the whole results in being simpler than those previously proposed in the literature.
Predictive algorithm for the roll control autopilot of a jet fighter aircraft
Authors: Kassapakis E. G. , Warwick K.
Published: July 2007

Predictive controllers are often only applicable for open‐loop stable systems. In this paper two such controllers are designed to operate on open‐loop critically stable systems, each of which is used to find the control inputs for the roll control autopilot of a jet fighter aircraft. It is shown how it is quite possible for good predictive control to be achieved on open‐loop critically stable systems.
Membership function shape and the dynamic behaviour of fuzzy systems
Authors: Baglio S. , Fortuna L. , Graziani S. , Muscato G.
Published: July 2007

In this paper the influence of the shape of the membership functions on the dynamic behaviour of a fuzzy controlled system is investigated. Although several works on fuzzy logic have been presented in the literature, few efforts have been made to characterize the dynamic behaviour of a fuzzy system through the shape of the membership functions. A parametrization for a class of membership functions is introduced in this work, resulting in a variety of shapes. Various system steady state dynamics are analysed as a consequence of this change in shape and chaotic dynamics is shown to arise for some membership function shapes.
Adaptive dead‐beat control law for trajectory tracking of robotic manipulators
Authors: Jetto L. , Longhi S. , Papini A.
Published: July 2007

The purpose of this paper is to propose an adaptive dead‐beat controller for the trajectory tracking of a robotic manipulator. the dead‐beat compensator is self‐tuned to a linearized discretized model whose parameters are identified on‐line through a Kalman‐like estimator. to improve the convergence of the estimator and to obtain good control performances even in the case of time‐varying parameters, the state covariance matrix of the Kalman filter is adapted to the observed statistics of the innovation process. Numerical results have been obtained in a simulation context and refer to various operating conditions. They show that very good control performances in terms of maximum error are really obtainable. A comparison with minimum variance control is also reported.
Optimality properties in finite sample liidentification with bounded noise
Authors: Kacewicz B. , Milanese M.
Published: July 2007

In this paper we investigate finite sample optimality properties for worst‐case l2identification of the impulse response of discrete time, linear, time‐invariant systems. the experimental conditions we consider consist ofmexperiments of lengthN.the measured outputs are corrupted by component‐wise bounded additive disturbances with known bounds. the quantification of the identification error is given by the maximum l1‐norm of the difference between the true impulse response samples and the estimated ones, where the maximum is taken with respect to all admissible plants and all admissible disturbances.

First we show that for any given experimental condition, almost‐optimal (within a factor of two) estimates can be obtained by solving suitable linear programmes.

Then we study how experimental conditions affect the identification error. Optimality of the experimental data is measured by the diameter of information, a quantity which is at most twice as large as the minimal worst‐case error.

We show that the minimum number of experiments allowing us to minimize the diameter of information is m−= 2−N. the values of the diameter of information and the corresponding optimal inputs are derived for the two extreme experimental conditions m = 1 and m = 2−N.
Uncertainty evaluation for estimates from recursive projection algorithms
Authors: Belforte G.
Published: July 2007

In this paper we consider parameter estimation of linear systems described byyi=aθ +ei, where the ith measurementyiis linearly dependent on the parameter vector θ ε ℝ−pthrough the regressor vectoraε ℝ−pand the measurement erroreiis unknown but bounded.

Some properties of previously presented algorithms for recursive parameter identification in the unknown but bounded error (UBBE) context are discussed. In particular it is analysed how different levels of information on the error structure can influence the choice of the identification algorithms and the possibility of evaluating the reliability of the estimates. Attention is also focused on the influence that forgetting schemes have on the estimates and on their confidence evaluation.
An extension of Nyquist's theorem to non‐uniformly sampled finite length data
Authors: Belmont M. R.
Published: July 2007

This paper examines non‐uniformly sampled functions on a finite interval. the aim is to investigate what conditions must be satisfied in order to recover the baseband spectrum from such data. It is shown that the concept of band limitation inherent in Nyquist's theorem must be generalized into a quantity termed primary interval bandwidth limitation. This property is explored and various algorithms are developed, including an extension of the classical band‐limited interpolation formula. Measures are obtained that provide guidelines for assessing where approximate techniques can be employed and the use of these in adaptive scenarios is considered. the key results are illustrated by a set of numerical examples. the findings are presented in the context of time variables, but the approach is applicable to any type of sample domain. the treatment is one‐dimensional, as are the examples discussed, but the extension to multiple dimensions is immediate and straightforward.
Technical note self‐tuning ziegler‐nichols pid controller
Authors: Bobál Vladimír
Published: July 2007

A new digital self‐tuning PID controller (STC PID) algorithm has been derived in this paper. the parameters of this controller are designed on the basis of a modified Ziegler‐Nichols criterion for digital control loops. the process is modelled as a controlled regression and its parameters are estimated using the recursive least squares method (RLSM) with LD decomposition and with directional forgetting applied. the algorithm is suitable for automatic setting of digital PID controllers for the control of deterministic processes or the adaptive control of stochastic processes.
A new indirect adaptive algorithm for feedforward control with application to active noise cancellation
Authors: Wang Angela Kuo , Ren Wei
Published: July 2007

This paper considers the deterministic adaptive feedforward control problem for disturbance rejection. A new indirect adaptive control algorithm is presented as an alternative to the well‐known ‘filtered‐X LMS’ algorithm when the disturbance is periodic with unknown frequency and the plant, possibly non‐minumum phase, is unknown. This new algorithm requires the solution of a Diophantine equation and a simple scheme to recursively solve this type of equation is suggested. the new algorithm is shown to converge without the use of a dither signal for plant modelling. Simulations demonstrate that the proposed algorithm has a substantially better transient response and convergence speed than the filtered‐X LMS algorithm. the applicability of the algorithm to the adaptive active‐noise‐cancelling problem is demonstrated using an identified acoustic model.
Amplitude‐constrained adaptive lqg control of first‐order systems
Authors: Królikowski A.
Published: July 2007

This paper considers the problem of adaptive LQG control design when the system control input is subject to an amplitude constraint. A first‐order stochastic system is considered mainly because its output can be satisfactorily described by a Gaussian probability density function (PDF) or can be calculated numerically. In this light, two algorithms are proposed. In the first algorithm an approach given by Toivonen has been adopted where the PDF of the output is approximated by the Gaussian density in order to develop a suboptimal adaptive feedback controller. the approach in the second algorithm is based on the numerically calculated PDF of the system output yielding a near‐optimal feedback gain. the proposed algorithms are compared with existing ones via simulations.
Godard blind equalizer error surface characteristics: White, zero‐mean, binary source case
Authors: Johnson C. Richard , Anderson Brian D. O.
Published: July 2007

We study the Godard/CMA error surface in adapting the impulse response coefficients of a finite‐length, tapped‐delay‐line filter to equalize a white, zero‐mean, binary (± 1) source that suffers ISI due to a linear channel. Our results arise primarily from examination of the expressions for the gradient and the Hessian in the baud‐spaced equalizer parameter space of the cost‐function in this particular setting. This paper presents results useful in topological assessment of predures for initializing a gradient descent algorithm on this multimodal surface in the equalizer parameter space.
Directly computableL2andL∞performance bounds for morse's dynamic certainty equivalence adaptive controller
Authors: Datta Aniruddha , Ioannou Petros A.
Published: July 2007

In this paper we consider a model reference adaptive control scheme where the classical error augmentation and standard tuning error normalization are avoided through the use of Morse's high‐order tuner. We consider the particular scheme of Morse where the concept of dynamic certainty equivalence is used to reduce the error equation to one that involves only first‐order dynamics. With such an error equation, it is first shown that one can directly obtain computableL∞ andL∞ bounds on the tracking error. This is an improvement over some earlier results where either only localL∞ bounds were obtained or the calculation of the global bounds required additional computation. Second, inserting an adaptive gain into Morse's high‐order tuner, we show that fast adaptation improves both the L2andL∞ bounds on the tracking error, in the sense that the effect of the parametric uncertainty on these bounds is attenuated. Finally, using a simple example, we demonstrate how an earlier attempt to use the adaptive gain to simultaneously attenuate the effect of the parametric uncertainty as well as the initial conditions on the L2bound for the tracking error has led to an incorrect result.
Co‐ordinate transformation in back‐stepping design for a class of non‐linear systems
Authors: Zhan Wei , Wang Le Yi
Published: July 2007

In this paper the problem of existence and construction of a co‐ordinate transformation is investigated for non‐linear systems appearing in feedback linearization and back‐stepping adaptive control problems. Conditions are derived to completely characterize the classes of non‐linear systems that are transformable to the simple triangular and parametric simple triangular forms via linear transformations. the conditions are shown to be invariant under linear co‐ordinate transformations and non‐linear feedback. For systems satisfying these conditions, the development of the co‐ordinate transformation is shown to be equivalent to that of their first‐order approximations and is straightforward.
Issues in nonlinear stochastic grey box identification
Authors: Bohlin Torsten , Graebe Stefan F.
Published: July 2007

Grey box identification refers to the practice of identifying dynamical systems in model structures exploiting partial prior information. This contribution reviews a method for stochastic grey box identification and surveys experiences and lessons of applying it to a number of industrial processes. Issues to be addressed include advantages and costs of introducing stochastics into the model, the question of what contribution must be expected from the model designer as opposed to what can be formalized in computer algorithms, and an outlook on future plans to resolve present shortcomings.
Experiment design for grey box identification
Authors: Sadegh P. , Holst J. , Madsen H. , Melgaard H.
Published: July 2007

Grey box models are characterized by their physical significance e.g. in parametrization and by the partial prior information that is available about e.g. the parameter values. These aspects of the grey box model affect the design of optimal excitations for identification and we study the extension of classical theory for experiment design to input design for identification of grey box models. Partial prior information is expressed as a probability distribution and is employed in the design of optimal excitations through optimization of Bayesian criteria.
Grey box modelling for control: Qualitative models as a unifying framework
Authors: Jørgensen S. Bay , Hangos Katalin M.
Published: July 2007

Grey box modelling traditionally reflects that both a priori and experimental knowledge are being incorporated into the model‐building process, where both of them may exhibit uncertain character. A brief investigation into various grey box modelling approaches reveals that they differ mainly with respect to the required model accuracy. Moreover, the goal of the model application has to be considered in the model building, since this goal defines the desired accuracy of the model, which is represented as model uncertainty.

This paper advocates the view that grey box modelling is model building which incorporates uncertainty description. Qualitative differential and algebraic equations are proposed in this paper as a unifying framework for development of dynamic models with uncertainty. the steps in the model development cycle are defined for this unifying framework, wherein the computational complexity issues are addressed at each step. It is also shown how qualitative differential and algebraic equations can be specialized to important well‐known grey box model forms such as robust models with parametric uncertainty, constraint qualitative differential equations and digraph models. the presented concepts and grey box model forms are illustrated on a simple example: a heat exchanger with bypass.
Plant‐wide control of a hybrid process
Authors: de Prada C. , Sarabia D. , Cristea S. , Mazaeda R.
Published: July 2007

This paper deals with the model predictive control (MPC) of an industrial hybrid process where continuous and batch units operate jointly: the crystallization section of a sugar factory. The paper describes a plant‐wide predictive controller that takes into account, both, continuous objectives and manipulated variables, as well as those related to the discrete operation and logic of the batch units. The MPC is formulated with time events, so that a more efficient NLP optimization technique, instead of MINLP, could be applied. Adaptation is provided by model updating and error estimation. Results of the controller operation in an industrial simulator are provided. Copyright © 2007 John Wiley & Sons, Ltd.
The Architectural Relevance of Gordon Pask
Authors: Haque Usman
Published: July 2007

Sebastiano Brandolini describes the work of Antonio Citterio who, despite a low‐key personal presence on the Italian architectural scene and an architecture of quiet restraint, has gained an enviable international reputation for his elegant and ‘impeccably well‐made’ buildings. Copyright © 2007 John Wiley & Sons, Ltd.
Wearable Technologies, Portable Architectures and the Vicissitudes of the Space Between
Authors: Papadopoulos Despina
Published: July 2007

The omnipresence of the iPod and mobile phone has ensured portable and wearable technologies' highly privileged position in contemporary society. They are at the top of the pile where conspicuous consumption is concerned ‐ you only have to visit an Apple store on a Saturday afternoon to witness the degree to which this highly sought‐after gadgetry has become subject to consumer frenzy and speculation. Here, Despina Papadopoulos reviews the particular social and cultural impact of wearable devices. She also welcomes in a new generation of interactive designers who are investigating the human and emotional potential of emergent technologies. Copyright © 2007 John Wiley & Sons, Ltd.
It's All Inside My Head
Authors: Spiller Neil
Published: July 2007

The physical manifestations of built architecture are often discussed in terms of a single architect's inspiration, overemphasising and romanticising the intellectual contribution of the signature architect. Here Neil Spiller describes the extraordinary departure that Marcos Novak is undertaking at the University of California's Santa Barbara campus, where Novak's own scanned brain becomes a literal, reflexive generating force in the formation of a spatial environment. Copyright © 2007 John Wiley & Sons, Ltd.
Lighting the Cavern: ‘Alvar Aalto: Through the Eyes of Shigeru Ban’
Authors: Spens Michael
Published: July 2007

Michael Spens has an intimate working knowledge of the buildings of Alvar Aalto having supported a restoration programme for Aalto's Viipuri Library in Russia between 1993 and 1997, which involved professionals from Russia and Finland. Here he offers his thoughts on the recent Aalto exhibition at the Barbican. Copyright © 2007 John Wiley & Sons, Ltd.
The Crystal at the Royal Ontario Museum
Authors: Stanwick Sean
Published: July 2007

Sean Stanwick, the co‐author of Design City Toronto, describes Daniel Libeskind's crystalline centrepiece for Toronto, which has become a catalyst for the city's cultural and architectural renaissance. Copyright © 2007 John Wiley & Sons, Ltd.
Large mergers and acquisitions of European brewing groups—event study evidence on value creation
Authors: Ebneth Oliver , Theuvsen Ludwig
Published: July 2007

Acquisitions have been the growing trend in recent years, giving brewers the opportunity to enhance their degree of internationalization and market share remarkably through diverse one‐off deals. Larger brewers are faced with low prospects for volume growth in developed markets leading them to seek growth either via acquisition of other brewers or by aggressive participation in developing markets or both. This study employs event study analysis to examine 31 mergers and acquisitions among leading European brewing groups. Differences regarding the brewers' corporate success can be determined within the European peer group. The results are discussed by additionally comparing the performance of companies that experienced M&As and companies that did not. Managerial implications as well as future research propositions conclude this article. © 2007 Wiley Periodicals, Inc. Agribusiness 23: 377–406, 2007.
The composition of milk from free‐living common marmosets (Callithrix jacchus) in Brazil
Authors: Power Michael L. , Verona Carlos Eduardo , Ruiz‐Miranda Carlos , Oftedal Olav T.
Published: July 2007

Common marmosets, one of the smallest anthropoid primates, have a relatively high reproductive rate, capable of producing twins or triplets twice per year. Growth and development of infants is relatively rapid, and lactation is relatively short at less than 3 months. Although mean values for the proximate composition (dry matter, protein, fat and sugar) of captive common marmoset milks fall within anthropoid norms, composition is highly variable among individual samples, with concentrations of milk fat ranging from below 1 to over 10%. To examine the extent to which this variation might be a consequence of captive conditions, we collected milk samples from wild common marmosets freely living on a farm in the state of Rio de Janeiro, Brazil. The proximate composition of the milk samples was assayed using identical techniques as used for the captive marmoset milks. The composition of the milk of wild common marmosets was also variable, but tended to be lower in dry matter, fat, protein and gross energy, and higher in sugar than milks from captive animals. Interestingly, the percentage of estimated gross energy from the protein fraction of the milks was relatively constant in both wild and captive marmosets and did not differ between wild and captive animals: 1 kcal of common marmoset milk contains on average (±SEM) 0.035±.001 g of protein regardless of the gross energy content of the milk or whether the milk was from a wild or captive animal. In contrast, in 1 kcal of low‐energy milks, the amount of sugar was significantly higher and the amount of fat significantly lower than in 1 kcal of high‐energy milks. Thus, common marmoset milk exhibits axes of variability (especially fat concentration) as well as a significant stability in the relative amount of protein. Am. J. Primatol. 70:78–83, 2008. © 2007 Wiley‐Liss, Inc.
Circadian cortisol secretion and circadian adrenal responses to ACTH are maintained in dexamethasone suppressed capuchin monkeys (Cebus apella)
Authors: Torres‐Farfan Claudia , Valenzuela Francisco J. , Ebensperger Renato , Méndez Natalia , Campino Carmen , Richter Hans G. , Valenzuela Guillermo J. , Serón‐Ferré María
Published: July 2007

We tested the hypothesis that the capuchin monkey adrenal (Cebus apella) gland has oscillatory properties that are independent of adrenocorticotropic hormone (ACTH) by exploring under ACTH suppression by dexamethasone: (i) maintenance of a circadian rhythm of plasma cortisol and (ii) clock time dependency of plasma cortisol response to exogenous ACTH. The capuchin monkey had a clear ACTH and plasma cortisol rhythm. Dexamethasone treatment resulted in low non‐rhythmic ACTH levels and decreased cortisol to 1/10 of control values; nevertheless, the circadian rhythm of plasma cortisol persisted. We found that cortisol response to exogenous ACTH was clock time‐dependent. The maximal response to ACTH occurred at the acrophase of the cortisol rhythm (0800 h). These results suggest that the capuchin monkey adrenal cortex may possess intrinsic oscillatory properties that participate in the circadian rhythm of adrenal cortisol secretion and in the circadian cortisol response to ACTH. Am. J. Primatol. 70:93–100, 2008. © 2007 Wiley‐Liss, Inc.
Systems design means process precision, but emphasizes culture, value, and results
Authors: Lewis Melanie
Published: July 2007

The issue: What does a comprehensive internal dispute resolution system look like?

The problems: Is it current? Is it responsive? Is it effective?

The perspective: Melanie Lewis, of Atlanta, describes how Coca‐Cola Enterprises Inc. assesses its conflict resolution needs, as well as how it implements, operates, and monitors its program–including provisions to redesign for new developments
You're letting 'em choose the mediator? Your case isn't that good! Getting to settlement demands mutual participation in selection
Authors: Kichaven Jeff
Published: July 2007

Jeff Kichaven, of Los Angeles, writes that participating actively in selection heightens commitment to the process‐and the likelihood of resolution
Synthesis and photoinduced surface‐relief grating of well‐defined azo‐containing polymethacrylates via atom transfer radical polymerization
Authors: Wang Gang , Zhu Xiulin , Wu Jianhong , Zhu Jian , Chen Xinrong , Cheng Zhenping
Published: July 2007

A well‐defined photoresponsive polymethacrylate containing azo chromophores, poly[6‐(4‐phenylazophenoxy)hexylmethacrylate] [Poly(PPHM)], was prepared with azo‐based monofunctional and difunctional initiators via atom transfer radical polymerization in the presence of CuCl/1,1,4,7,10,10‐hexamethyltriethylenetetramine. The polymerizations with first‐order kinetics were well controlled with theoretical expected molecular weight and narrow molecular weight distributions in two initiation systems. The UV absorption intensities of the poly (PPHM)s increased with increasing molecular weight of the poly(PPHM)s in all cases. The 80‐nm surface‐relief gratings with 2.7% efficient diffraction formed on the poly (PPHM) film surface were obtained with a linearly polarized krypton laser with 10 min of irradiation at a recording beam intensity of 188 mW/cm2 with a wavelength of 413.1 nm. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007
Medium‐density particleboards from rice husks and soybean protein concentrate
Authors: Leiva P. , Ciannamea E. , Ruseckaite R. A. , Stefani P. M.
Published: July 2007

Rice husks are a valuable agricultural residue produced worldwide with potential applications as a wood substitute in particleboard manufacturing. In this work, the feasibility of producing medium‐density particleboards based on waste rice husks bonded with environmentally friendly adhesives from soybean protein concentrate was analyzed. The mechanical properties, internal bond strength, and water resistance of the obtained panels bonded with the homemade soybean protein concentrate adhesives were compared to those of boards glued with commercial adhesives such as phenol–formaldehyde and urea–formaldehyde resins. An alkaline treatment improved the gluing ability of the soybean protein concentrate. The mechanical properties of the alkali‐treated soybean protein concentrate were comparable to those determined for panels with urea–formaldehyde. The lower water resistance of the alkali‐treated soybean protein concentrate particleboards, compared with that of the formaldehyde‐based resins, was counterbalanced by the advantage of being more environmentally sound, which makes them suitable for applications for which the requirements for water resistance are not stringent. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Production of low‐molecular‐weight natural rubber: Comparative assessment of a nonchemical route
Authors: Okwu U. N. , Akinlabi A. K.
Published: July 2007

The use of Funtumia latex and nitrobenzene as molecular weight depressants for natural rubber was studied. Portions of a given sample of natural rubber latex were treated with these materials, and this provided a means of ascertaining the amount of Funtumia latex in a blend with natural rubber that could produce a lowering of the molecular weight equivalent to that from known concentrations of nitrobenzene in natural rubber latex. The molecular weight of the products decreased to an equilibrium value after 10 h of reaction with nitrobenzene. The calculations revealed that a 27.9% substitution of natural rubber latex (300 mL) with Funtumia rubber latex achieved the same result as nitrobenzene in the same polymer at concentrations of 0.5–2.0 wt % of the dry rubber content of the latex after 10 h of reaction. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Molecular weight studies of the γ‐irradiation degradation of poly(methyl methacrylate) doped with poly(p‐sulfanilamide)
Authors: Sayyah S. M. , Khaliel A. B. , Abd El‐Salam H. M.
Published: July 2007

The protection of some poly(methyl methacrylate) (PMMA) samples against γ rays was investigated in the absence and presence of poly(p‐sulfanilamide). Pure PMMA (without additives) and PMMA–poly(p‐sulfanilamide) blend samples were irradiated with γ rays for different exposure doses (5, 15, 25, 35, 50, 75, and 100 kGy). The viscosity‐average molecular weights were determined and thin‐layer chromatography measurements were carried out after each irradiation dose. The maximum protection against γ rays was found when 1% poly(p‐sulfanilamide) was used. The radiation chemical yield for main scission (Gs) was calculated and had lower values in the case of 1% poly(p‐sulfanilamide). The energy absorption per scission was maximum for 1% poly(p‐sulfanilamide), and this confirmed the obtained Gs data. From thin‐layer chromatography studies, it was observed that both the retention factor (Rf) values and polydispersity of the PMMA samples increased with an increasing exposure dose. The effect of γ irradiation on PMMA films doped with 1% poly(p‐sulfanilamide) was investigated with UV spectroscopy after the extraction of the additives. A change in the intensity of the absorption bands with an increasing irradiation dose was recorded. It is suggested that PMMA films doped with this type of polymer can be used as dosimeters. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Synthesis, characterization, ion‐exchange, and antimicrobial study of poly[(2‐hydroxy‐4‐methoxybenzophenone) propylene] resin and its polychelates with lanthanides (III)
Authors: Patel M. M. , Kapadia M. A. , Patel G. P. , Joshi J. D.
Published: July 2007

The polymeric ligand (resin) was prepared from 2‐hydroxy‐4‐methoxybenzophenone with 1,3‐propane diol in the presence of polyphosphoric acid as a catalyst on constant heating at 160°C for 13 h. The poly[(2‐hydroxy‐4‐methoxybenzophenone) propylene] (HMBP‐PD) form 1 : 2 metal/ligand polychelates (metal–polymer complexes) with La(III), Pr(III), Nd(III), Sm(III), Gd(III), Tb(III), and Dy(III). The polymeric ligand and its polychelates (metal–polymer complexes) were characterized on the basis of elemental analyses, electronic spectra, magnetic susceptibilities, IR‐spectroscopy, NMR, and thermogravimetric analyses. The molecular weight was determined using number average molecular weight (Mn) by a vapor pressure osmometry (VPO) method. Activation energy (E) of the resin was calculated from differential scanning calorimetry (DSC). All the polychelates are paramagnetic in nature except La(III). Ion‐exchange studies at different electrolyte concentrations, pH, and rate have been carried out for lanthanides(III) metal ions. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Profile‐based push models in manpower planning
Authors: Guerry Marie‐Anne
Published: July 2007

A methodology is presented to deal with heterogeneity due to observable variables in modeling personnel systems. For a manpower system, a model based on personnel profiles is introduced. The proposed algorithm concerns an analysis of the evolution of personnel profiles under time‐discrete Markov assumptions. In this way, based on an historical personnel database, the estimation of transition probabilities of profiles as well as the computation of forecasts on the evolution of the manpower system can be found. Based on the presented procedure, a policy supporting software package has been developed for the Belgian Federal Government (research project financed by Federaal Wetenschapsbeleid). Copyright © 2007 John Wiley & Sons, Ltd.
Alimentary hyperlipemia of rabbits is affected by exposure to low‐intensity pulsed magnetic fields
Authors: Luo Erping , Shen Guanghao , Xie Kangning , Wu Xiaoming , Xu Qiaoling , Lu Lihua , Jing Xiaomei
Published: July 2007

An experimental study was carried out in rabbits to investigate the effects of exposing rabbits to low‐intensity pulsed magnetic fields (PMFs) on alimentary hyperlipemia. Thirty female white big ear rabbits were randomly divided into three groups. The normal group was fed with a standard chow diet and the other two groups (hyperlipid and magnetic) were fed with the chow diet supplemented with cholesterol, yolk powder and lard. The magnetic group was exposed to 15 Hz pulsed magnetic fields. After 8 weeks, levels of blood lipid and indices of hemorheology were examined. In addition, histomorphologic changes of hepatic and myocardial tissues were compared across the groups respectively. Compared with the hyperlipid group, hemorheology indices of the magnetic group reduced significantly from 12.80% to 38.05% (P < 0.01) indicating lower blood viscosity. Similarly, compared with the hyperlipid group, the levels of total cholesterol and triglycerides in the magnetic group decreased 40.52% and 52.42% (P < 0.01). On the contrary, high density lipoprotein (HDL) value obviously increased 66.67% (P < 0.01). Furthermore, compared with the control group, the values of triglycerides and HDL of the magnetic group did not show statistical differences (P > 0.05). The deposit of fatty material on the inner lining of thoracic aorta wall of the magnetic group was significantly lighter than that of the hyperlipid group. Numerous aggregation of lipoids emerged among myocardial myofibrils in the hyperlipid group, while no notable change was found in both the magnetic and control group. The results indicate that low‐intensity PMFs could be helpful for the treatment of alimentary hyperlipemia. Bioelectromagnetics 28:608–614, 2007. © 2007 Wiley‐Liss, Inc.
Permeability changes induced by 130 GHz pulsed radiation on cationic liposomes loaded with carbonic anhydrase
Authors: Ramundo‐Orlando Alfonsina , Gallerano Gian Piero , Stano Pasquale , Doria Andrea , Giovenale Emilio , Messina Giovanni , Cappelli Mauro , D'Arienzo Marco , Spassovsky Ivan
Published: July 2007

The effects of pulsed 130 GHz radiations on lipid membrane permeability were investigated by using cationic liposomes containing dipalmitoyl phosphatidylcholine (DPPC), cholesterol, and stearylamine. Carbonic anhydrase (CA) was loaded inside the liposomes and the substrate p‐nitrophenyl acetate (p‐NPA) added in the bulk aqueous phase. Upon permeation across the lipid bilayer, the trapped CA catalyzes the conversion of the p‐NPA molecules into products. Because the self‐diffusion rate of p‐NPA across intact liposomes is very low the CA reaction rate, expressed as ΔA/min, is used to track membrane permeability changes. The effect of 130 GHz radiation pulse‐modulated at low frequencies of 5, 7, or 10 Hz, and at time‐averaged incident intensity (IAV) up to 17 mW/cm2 was studied at room temperature (22 °C), below the phase transition temperature of DPPC liposomes. At all the tested values of IAV a significant enhancement of the enzyme reaction rate in CA‐loaded liposomes occurred when the pulse repetition rate was 7 Hz. Typically, an increase from ΔA/min = 0.0026 ± 0.0010 (n = 11) to ΔA/min = 0.0045 ± 0.0013 (n = 12) (P < 0.0005) resulted at IAV = 7.7 mW/cm2. The effect of 130 GHz pulse‐modulated at 7 Hz was also observed on cationic liposomes formed with palmitoyloleoyl phosphatidylcholine (POPC), at room temperature (22 °C), above the phase transition temperature of POPC liposomes. Bioelectromagnetics 28:587–598, 2007. © 2007 Wiley‐Liss, Inc.
The evolving concept of tumor microenvironments
Authors: Laconi Ezio
Published: July 2007

The role of the microenvironment in cancer development is being increasingly appreciated. This paper will review data that highlight an emerging distinction between two different entities: the microenvironment that altered/preneoplastic/neoplastic cells find in the tissue where they reside, and the peculiar microenvironment inside the focal lesion (tumor) that these cells contribute to create. While alteration in the tissue environment can contribute to the selective clonal expansion of altered cells to form focal proliferative lesions, the atypical, non‐integrated growth pattern that defines such focal lesions leads to the appearance of what is correctly referred to as the tumor microenvironment. The latter represents a new and unique biological milieu, characterized by hypoxia, acidosis and other biochemical and metabolic alterations, including genetic instability, that can set the stage for tumor progression to occur. Thus, the two microenvironments act in sequence and play complementary roles in the development of overt neoplasia. This distinction has important implications for the understanding of disease pathogenesis and for the management of preneoplastic/neoplastic lesions at various stages of cancer development. BioEssays 29:738–744, 2007. © 2007 Wiley Periodicals, Inc.
Deconstructing digit chondrogenesis
Authors: Montero Juan A. , Hurlé Juan M.
Published: July 2007

Chondrogenesis is a key process in skeletogenesis since endochondral ossification requires the formation of a cartilaginous template. Knowledge of molecular mechanisms regulating chondrogenesis is extremely valuable not only to understand many human disorders but also in regenerative medicine. Embryonic skeletogenesis is an excellent model to study this mechanism. Most cartilages share the cellular basis underlying chondrogenesis but the high heterogeneity in morphologies of the different skeletal elements appears to be generated by differential participation of a variety of chondrogenic signals. Here we overview the regulatory factors responsible for chondrogenesis concluding that early chondrogenic signals for the digit cartilages differ from those implicated in the formation of other axial and appendicular skeletal components. BioEssays 29:725–737, 2007. © 2007 Wiley Periodicals, Inc.