bluuebunny/crossref_metadata_2025 huggingface dataset:
Digestion of peanut allergens Ara h 1, Ara h 2, Ara h 3, and Ara h 6: A comparative in vitro study and partial characterization of digestion‐resistant peptides
Authors: Koppelman Stef J. , Hefle Sue L. , Taylor Steve L. , de Jong Govardus A. H.
Published: July 2010

Scope: There are differences in stability to pepsin between the major allergens in peanut; however, data are from different reports using different digestion models. This study provides a comprehensive comparison of the digestibility of the major peanut allergens.

Methods and results: Peanut allergens Ara h 1, Ara h 2, Ara h 3 and Ara h 6 were incubated with pepsin to mimic the effect of gastric digestion. Samples were analyzed using SDS‐PAGE. To further investigate resistance to digestion, Ara h 2 was additionally subjected to digestion with trypsin and residual peptides were characterized. Ara h 1 and Ara h 3 were rapidly hydrolyzed by pepsin. On the contrary, Ara h 2 and Ara h 6 were resistant to pepsin digestion, even at very high concentrations of pepsin. In fact, limited proteolysis could only be demonstrated by SDS‐PAGE performed under reducing conditions, indicating an important role for the disulfide bridges in maintaining the quaternary structure of Ara h 2 and Ara h 6. Trypsin digestion of Ara h 2 similarly resulted in large residual peptides and these were identified.

Conclusion: Ara h 2 and Ara h 6 are considerably more stable towards digestion than Ara h 1 and Ara h 3.
Nukleinsäuren in verschiedenen Probenvolumina analysieren
Authors: Brescia Peter , Banks Peter , Bruss Marina
Published: July 2010

Gleichgültig, ob Polymerasekettenreaktion oder Klonierung: Es muss bekannt sein, wie konzentriert eine Nukleinsäurelösung ist. Biotek hat ein Spektralphotometersystem entwickelt, das DNA‐ und RNA‐Gehalte zuverlässig bestimmt.
Lähmendes Halbwissen
Authors: Osterath Brigitte
Published: July 2010

Brigitte Osterath

Um nach einem Vulkanausbruch die richtigen Entscheidungen für die Luftfahrt zu treffen, müssen Wissenschaftler schnell und zuverlässig Aschewolken vermessen. Doch die Methoden dazu stecken noch in den Kinderschuhen. Auch an der Organisation hapert es: Nicht eine zentrale Stelle, sondern viele einzelne Arbeitsgruppen versuchten im April, der Asche des Eyjafjallajökull auf die Spur zu kommen.
Effects of constitutive parameters on strain localization in sands
Authors: Gutierrez Marte
Published: July 2010

This paper presents an analysis of the effects of constitutive parameters on bifurcation and shear band formation in granular soils. Strain localization is analyzed in terms of Vermeer's compliance approach, which is re‐derived and generalized in this paper. The paper also shows that Vermeer's compliance approach is equivalent to other more complex localization criteria. A simple elastoplastic constitutive model for biaxial loading condition is introduced, which adequately captures the monotonic response of granular soils particularly the variation of dilatancy and mobilized friction with shear deformation. Using the constitutive model, the strain localization criterion is expressed in terms of constitutive parameters. Both the model and the strain localization criterion are verified against the experimental data. The model and the localization criterion are then applied in a parametric study to determine the sensitivity of strain localization in granular soils to constitutive parameters. Published in 2010 by John Wiley & Sons, Ltd.
A new parabolic variational inequality formulation of Signorini's condition for non‐steady seepage problems with complex seepage control systems
Authors: Chen Yifeng , Hu Ran , Zhou Chuangbing , Li Dianqing , Rong Guan
Published: July 2010

By extending Darcy's law to the dry domain above the free surface and specifying the boundary condition on the potential seepage surfaces as Signorini's type, a partial differential equation (PDE) defined in the entire domain of interest is formulated for non‐steady seepage flow problems with free surfaces. A new parabolic variational inequality (PVI) formulation equivalent to the PDE formulation is then proposed, in which the flux part of the complementary condition of Signorini's type in the PDE formulation is transformed into natural boundary condition. Consequently, the singularity at the seepage points is eliminated and the difficulty in selecting the trial functions is significantly reduced. By introducing an adaptive penalized Heaviside function in the finite element analysis, the numerical stability of the discrete PVI formulation is well guaranteed. The proposed approach is validated by the existing laboratory tests with sudden rise and dropdown of water heads, and then applied to capture the non‐steady seepage flow behaviors in a homogeneous rectangular dam with five drainage tunnels during a linear dropdown of upstream water head. The non‐steady seepage flow in the surrounding rocks of the underground powerhouse in the Shuibuya Hydropower Project is further modeled, in which a complex seepage control system is involved. Comparisons with the in situ monitoring data show that the calculation results well illustrate the non‐steady seepage flow process during impounding and the operation of the reservoir as well as the seepage control effects of the drainage hole arrays and drainage tunnels. Copyright © 2010 John Wiley & Sons, Ltd.
Understanding customer satisfaction in opera: first steps toward a model
Authors: Jobst Johanna , Boerner Sabine
Published: July 2010

Despite the frequent call for a strengthened customer orientation in performing arts organizations, no efforts have been made to investigate customer satisfaction in opera so far. The paper aims at filling this gap by suggesting a first integrative model of customer satisfaction in opera. This model integrates insights from both services marketing literature (i.e., general services marketing and performing arts marketing) and performing arts literature (i.e., music perception and theater studies). The model is tested in a field study interviewing 116 visitors of a public German opera house. Results reveal visitors' level of appraisal to be the main antecedent of their satisfaction, followed by their perception of the artistic quality, empathy/identification with the actors on stage, and recall from memory. Furthermore, differences within the audience regarding the relative importance of the antecedents of customer satisfaction in opera are investigated. Using gender and attendance frequency as segmentation variables, only minor differences are found, though. Managerial implications for opera marketing are discussed in conclusion. First, efforts in opera marketing should rather concentrate on the core service quality instead of the peripheral service quality. Second, professional opera companies may attract broader audiences if they focus on the emotional satisfaction of their customers. Third, since only minor and mostly insignificant differences between men and women, and occasional compared to frequent visitors are found, a need for further research to explore alternative segmentation variables in the opera context is identified.

Copyright © 2010 John Wiley & Sons, Ltd.
The impact of case reports relative to other types of publication in palaeopathology
Authors: Mays S.
Published: July 2010

Despite repeated calls for palaeopathology to move away from descriptive case reports towards quantitative, problem‐orientated work, case reports still form a high proportion of palaeopathology journal publications. This work assesses, using citation analysis, the impact of the case report relative to that of other types of study in palaeopathology. Results suggest that case studies are cited less often than other types of publication, but that this deficit is less marked than in the clinical sciences where the case report has been effectively marginalised. It is suggested that although a reduction in the proportion of publications in palaeopathology made up of case reports may be desirable, and would be an indication of maturation of the discipline, well‐directed case reports will continue to play a role, albeit a diminishing one, in advancing the field. Copyright © 2010 John Wiley & Sons, Ltd.
Legg–Calvé–Perthes Disease and unifocal eosinophilic granuloma in a visigoth from the Duratón necropolis (Segovia, Spain)
Authors: Herrerín J. , Garralda M. D.
Published: July 2010

Individual number 12, exhumed at the Duratón Visigoth necropolis (Segovia, Spain), was found in a supine position inside a simple fossa without adornments. He was a very robust adult (∼50/60 years) male presenting two pathologies, independently originated and both occurring in a particular anatomical area: the right hip. The first one has been diagnosed as Legg–Calvé–Perthes Disease, and it affects the right femur and the coxal. The femoral head has a diameter that is much greater than usual, with a porous articular surface, no fovea capitis and a marked arthritic secondary growth which is inserted in the femoral neck; the coxal shows a pathological acetabulum larger than the left one, and having osseous borders. The second disease, considered a unifocal eosinophilic granuloma, is in the inner face of the right ilium, and practically occupies the whole iliac fossa. The development of the two pathologies and their probable repercussions on the individual's mobility, on the basis of the study of both the pathological and normal pieces recovered, are discussed. Copyright © 2010 John Wiley & Sons, Ltd.
Optimal control of Markovian queueing systems
Authors: Klein C. F. , Gruver W. A.
Published: July 2010

Dynamic optimization of queueing systems is treated by optimal control theory. This work is based on modelling the queueing problem as a time‐varying continuous Markov chain. Necessary and sufficient conditions are given for a broad class of problems which include both scalar and Markovian dynamic programming control structures. Continuity of the switching function is used to characterize optimality near the end points of the horizon. Special properties of the model are exploited to ensure the absence of singular subarcs. Numerical results based on the use of a gradient algorithm report the effect of increasing the system capacity, a comparison of scalar versus Markovian dynamic programming controls, and an application to a multiprogrammed computer system.
Adjustment costs and the theory of optimal investment and financing of the firm
Authors: Lin Winston T.
Published: July 2010

A dynamic optimal‐control based model that explicitly includes the effects of adjustment costs of investment and financing is presented to analyse the investment and financing decisions of a present value‐maximizing firm. The model is constrained by an equity‐capital formation and a linear homogeneous earnings‐investment possibility function composed of two components: an adjustment‐cost function and an ordinary production function. Pontryagin's maximum principle is used to solve the model. The main results derived from the model include an optimal investment decision rule, an optimal investment‐financing plan, the long‐run equity demand for the firm, and the long‐run behaviour of investment and financing as they are affected by the existence of adjustment costs.
Some basic algebraic relations in the order‐reduction of large‐scale systems by aggregation
Authors: Ying‐Ping Zheng
Published: July 2010

In this paper, we prove conditions for the existence of a full‐rank matrix K which satisfies the aggregation relations (4)–(6). These conditions are convenient for checking and offer some rules for selecting K. Theorem 3 shows the properties of the matrix F in the aggregated model. It is actually a generalization of the important algebraic theorem on the similarity transformation of matrices.
Solution of ill‐conditioned optimality conditions for control of turbo‐alternators
Authors: Shamaly A. , Christensen G. S. , El‐Hawary M. E.
Published: July 2010

The computational solution of the optimality equations for torque and voltage control of a large‐scale turbo‐alternator is considered. The equations are extremely ill‐conditioned as a consequence of the ill‐conditioning of the linearized system model. Our main result is to point out that using the Ricatti equation to estimate the initial values of the Lagrange multipliers renders the equations in a form that can easily be solved as an initial value problem for the non‐linear system.
An Approximation technique for small noise open‐loop control problems
Authors: Holland Charles J.
Published: July 2010

For a class of non‐linear open‐loop stochastic control problems with small additive white noise, an approximation technique to compute an optimal control of fixed structure related to the noise intensity is presented. The method developed here leads to a generalized deterministic linear regulator problem. It has the advantage that approximate optimal controls are obtained simultaneously for all sufficiently small noise levels. A numerical example is presented to illustrate the method.
Security‐level strategies for non‐linear stochastic pursuit‐evasion differential games
Authors: Chompaisal A. , Leondes C. T.
Published: July 2010

A first‐order algorithm is developed to solve for the security‐level strategies of differential games without an assumption that a saddle point exists. The inner optimization uses differential dynamic programming together with a convergence control method. The outer optimization uses a gradient method. The application of the algorithm is demonstrated by solving for numerical strategies for a realistic missile‐antimissile pursuit‐evasion problem. Two major advantages for this algorithm are that the initialization requires only a rough estimate of the nominal control and that the Hessian matrix of the Hamiltonian with respect to the control vector is positive (negative) definite for the minimization (maximization) problem only on the optimal path.
The homicidal chauffeur game—a Stochastic Model
Authors: Pachter M. , Yavin Y.
Published: July 2010

We consider a certain stochastic pursuit—evasion problem of the homicidal chauffeur type. Specifically, weshow that, in contrast to the less straightforward swerve manoeuvre employed in the deterministic model, the particularly simple bang‐bang pursuit strategy synthesized here is applicable to a significant range of problem parameters. The strategy of the slower but agile player is also characterized, and its geometric meaning isillustrated.
Optimal advertising for the Nerlove‐Arrow Model under a replenishable budget
Authors: Sethi S. P. , Lee S. C.
Published: July 2010

This paper considers an optimal control problem with two state variables for the dynamics of the Nerlove—Arrow advertising model. The optimal control is the rate of advertising expenditure required to maximize the present value of net profit streams over an infinite horizon subject to a replenishable budget. It is shown that an equilibrium level of advertising exists in all possible cases. It is interesting to note that this level happens to be non‐singular in some cases. Also shown is the optimal transient approach to these equilibrium levels.
Finite‐difference gradients versus error‐quadrature gradients in the solution of parameterized optimal control problems
Authors: Kraft D.
Published: July 2010

Two non‐linear programming algorithms based on the Lagrangian function are compared with respect to their computational efficiency for solving parameterized optimal control problems. If the most efficient, constrained variable metric method together with forward‐difference gradients is used, the formulation and implementation of the adjoint variables can be avoided. This is especially convenient in the design phase of large complex systems.
Computation of nash equilibrium pairs of a stochastic differential game
Authors: Yavin Y. , Reuter G.
Published: July 2010

Consider the random motion of two points Me and Mp in an open and bounded domain D0 in the plane. Each of the velocities, u = (u1 u2)T of Me and v = (v1, v2)T of Mp, are perturbed by a corresponding R2‐valued Gaussian white noise. Let A and Dc be two disjoint closed subsets of D0. Suppose that at t = 0, Me is in A and Mp is anywhere in D0. Denote by ℰ1 and ℰ2 the following events: ℰ1 = {Mp intercepts Me in A before Me reaches the set Dc and before either Me or Mp has left D0}, and ℰ2 = {Me reaches the set Dc before being intercepted by Mp, while Mp is in A, and before either Mp or Me has left D0}.

The problem dealt with here is to find a pair of velocity strategies (u*, v*) such that, in the sense of a Nash equilibrium point, the probabilities Prob(ℰ1) and Prob(ℰ2) will both be maximized on a given class of velocity strategies (u, v). Sufficient conditions on (u*, v*) are derived which require the existence of a smooth solution (V,Q) to a pair of coupled non‐linear partial differential equations. A finite‐difference scheme for solving these equations is suggested, and two examples are treated in detail.
A Local optimization procedure for a gas compressor station
Authors: Osiadacz A. , Bell D. J.
Published: July 2010

The optimal control of a gas compressor station is required which minimizes the costs of powering the compressors. An algorithm is developed which has a two‐level structure: an optimization level and a control/adjustment level. The former minimizes the engine fuel consumption with the use of measured values of flow through the station together with suction and discharge pressure. The latter level ensures proper operating conditions for the compressors and thereby reduces the cost of maintenance and repairs. The proposed procedure is illustrated by an example, and the results show that the method can lead to a significant saving in fuel consumption.
Suboptimal controller design for active control of circular saw vibrations
Authors: Cho H. S. , Cho Y. J.
Published: July 2010

A circular saw in operation can have an instability phenomenon which is characterized by a large amplitude and operation speed‐dependent vibration. In this paper, a method of suppressing such unstable motion is presented. An optimal output feedback control scheme is adopted, and only the output variables available from sensors are used. A truncated vibrational mode model is used to formulate the saw dynamics. This model incorporates the forces due to the actuators. Since the performance of controlling the saw motion depends greatly upon spatial locations of both actuators and sensors, their locations are optimally determined with respect to a prescribed performance index representing the vibrating system energy. A two‐mode simulation of a saw is made to illustrate the effectiveness of the control scheme. The results show that this proposed design method stabilizes the otherwise unstable motion of the saw and also requires a very short controlling time for vibration suppression.
An Optimal control approach to marketing‐production planning
Authors: Abad Prakash L.
Published: July 2010

The problem of finding an optimal advertising and production policy in a firm is analysed using a recently proposed model of a marketing‐production system. First, it is shown that the optimal control problem underlying the proposed model is a partially singular control problem. Then, a reverse‐time parametric solution procedure is designed to determine the optimal advertising and production policy for the proposed model. Finally, it is shown that the results derived from the new model are applicable to problems of capacity expansion in a firm.
Flexible spacecraft attitude measurement and control scheme incorporating state estimation
Authors: Fenton J. , Horton D. , Gill K. F.
Published: July 2010

The design of an attitude measurement and control scheme for a flexible space vehicle is presented. A proposed spacecraft configuration is used to study the performance of an inertial‐optical measurement system incorporating a Kalman filter to obtain the best estimates in the presence of differing noise models. These estimates are used to correct for gyroscope drift and also provide the information necessary to implement optimal attitude control with active damping of the flexural motion.
Optimal control of non‐linear distributed parameter systems by a finite‐element collocation technique
Authors: Rao K. C. , Prabhu S. S. , Mehta S. C.
Published: July 2010

A finite‐element collocation technique is proposed for solving non‐linear distributed parameter system (DPS) optimal control problems. On each element, two Gaussian collocation points and Hermite approximation functions are used in the finite‐element collocation technique. The numerical experience for two non‐linear DPS, one involving distributed control and the other involving spatially‐independent control, is reported. Optimal control of DPS can be computed with relatively low‐order models when this finite‐element collocation technique is used.
Time‐optimal control of an overhead crane model
Authors: Manson G. A.
Published: July 2010

Time‐optimal solutions for a simple crane model have been arrived at by a number of authors using expensive analogue methods. The method described in this paper also gives time‐optimal solutions but these can be obtained using a very simple microprocessor. These solutions are obtained quickly and inexpensively and thus can be used for comparison with other suboptimal solutions based on more complex and less idealized models. An extension of the method is also outlined which covers certain variants of the simple model.
Time‐scale decoupling and order reduction for linear time‐varying systems
Authors: O'Malley Robert E. , Anderson Leonard R.
Published: July 2010

The class of time‐varying linear systems which are two‐time‐scale on an interval may be decoupled by a transformation of variables into separate subsystems containing the slow and fast dynamic parts. The transformation is obtained by solving a non‐symmetric Riccati differential equation forward in time and a linear matrix differential equation backward in time. Small parameters are identified which measure the strength of the time‐scale separation and the stability of the fast subsystem. As these parameters go to zero, the order of the system is reduced, and a useful approximate solution to the original system is obtained. The transformation is illustrated for examples with strong and weak fast subsystem stability.
Controller design for parameter sensitivity reduction in linear regulators
Authors: Yedavalli Rama Krishna , Skelton Robert E.
Published: July 2010

This paper addresses the problem of parameter sensitivity reduction in linear regulators. It is shown that the minimization of a modified performance index which includes a quadratic term of trajectory sensitivity (state, output, or control) subject to the augmented sensitivity system dynamics causes reduction not only in trajectory sensitivity but also in cost sensitivity. Inclusion of both state sensitivity and control sensitivity terms in the cost functional reduces cost sensitivity and facilitates the unification of two approaches previously treated independently: ‘trajectory sensitivity reduction’ and ‘cost sensitivity reduction’. Two control design methods, one based on a linear formulation and the other on a non‐linear formulation, are given for both deterministic and stochastic systems. The improvement of these methods over existing methods is illustrated by examples.
Optimal Two‐Impulse Transfer Between Specified Terminal States Of Keplerian Orbits
Authors: Jezewski D. J.
Published: July 2010

The integrals of motion for an inverse‐square force field and a necessary condition for optimality are used in a transfer orbit co‐ordinate system to formulate the solution of the optimal two‐impulse transfer between fixed position and velocity vectors on Keplerian orbits. In this co‐ordinate system, the equations reveal two asymptotes that are useful in analysing the solution. It is shown that there are only two real extremals (both minimums) which are separated by an asymptote. An approximate analytic solution is also obtained by ignoring a quadratic term whose coefficient is approximately zero for a large class of orbit transfer problems.
Boost–glide range‐optimal guidance
Authors: Kelley H. J. , Cliff E. M. , Lutze F. H.
Published: July 2010

A simple guidance scheme is proposed which approximately optimizes the range of the glide phase of a boost‐glide vehicle's trajectory. The scheme requires only altitude, flight‐path angle, and attitude measurements for implementation. The guidance law provides an attitude command based on the actual flight‐path angle and on a calculated flight‐path angle associated with that of an equilibrium, constant‐dynamic‐pressure, glide of maximum lift‐to‐drag ratio. By proper weighting of these two inputs, an approximately optimal guidance control is realized. Two examples are given which demonstrate the trajectory characteristics for a high‐performance aircraft and for a missile‐type vehicle.
The control of environmental pollution and optimal investment and employment decisions
Authors: Lin Winston T.
Published: July 2010

This paper develops an optimal control model for the firm's decision‐making concerning pollution control spending, employment and investment. The model explicitly considers the impact of adjustment costs of changing the level of the pollution stock and involves three state variables and two control variables. Necessary conditions are derived by the maximum principle. The results include an optimal employment‐investment‐pollution abatement programme, an optimal pollution control decision rule, the equilibrium optimal pollution control and spending plan, and the equilibrium employment‐investment decision.
Relations between frequency‐dependent control and state weighting in LQG problems
Authors: Anderson B. D. O. , Moore J. B. , Mingori D. L.
Published: July 2010

This paper considers the relation between controller designs for the same linear system achieved with two different quadratic performance indices. These indices differ only to the extent that one has frequency weighting on the control whereas the other has the inverse frequency weighting on the state. The feedback controllers are constructed by augmenting the given plant and by solving a modified LQG problem for the augmented system. The main result is that whereas the optimal controls as time functions can be the same, the optimal controllers are different. Filtering results are also obtained.
A Newton‐like approximation algorithm for the steady‐state solution of the riccati equation for time‐varying systems
Authors: Emre Erol , Knowles Gareth
Published: July 2010

An approximation technique is developed for the steady‐state solution of the time‐varying matrix Riccati equation. We show how the Newton‐type algorithm of Kleinman, developed for computing the steady solution to the algebraic Riccati equation for time‐invariant systems, can be extended for time‐varying linear systems. The time‐varying case is considerably more involved than the time‐invariant one. Consider a linear time‐varying system x(t) = F(t)x(t) + G(t)u(t). If (F, G) is uniformly completely controllable, we show how one can construct a recursive sequence of matrix functions (using linear techniques) which converge to the steady‐state solution of the associated time‐varying matrix Riccati equation (a non‐linear object). At each successive state, the next approximation is in terms of the steady‐state solution to a linear Lyapunov differential equation (which is the extension of the algebraic Lyapunov equations used by Kleinman) for which an explicit expression exists. This provides an approximation technique for obtaining infinite‐time, linear‐quadratic, optimal controllers and steady‐state Kalman—Bucy filters for time‐varying systems using purely linear techniques. Thus, we provide new types of suboptimal stabilizing feedback laws for linear time‐varying systems.
On the control of an uncertain water quality system
Authors: Chen Y. H. , Lee C. S.
Published: July 2010

We consider a one‐reach water quality system subject not only to bounded uncertain disturbances at the input and output levels but also to bounded uncertain variations of the rate coefficients. When the bounds of the time‐varying uncertainties are known, two classes of robust controllers, based on the measured state, are proposed to assure some desired performance, including uniform boundedness and uniform ultimate boundedness. If only output rather than full state is available for the control, a class of estimated state‐based control is proposed for the desired performance. When the bounds of the uncertainties are not known, we propose a class of controllers which, using the functional properties of the uncertainties, guarantees some desired system properties, one of which is the convergence to zero of all system responses.
Risk behaviour and optimum advertising with a stochastic dynamic sales response
Authors: Tapiero Charles S. , Eliashberg Jehoshua , Wind Yoram
Published: July 2010

A stochastic (diffusion) sales response model to advertising is postulated. Optimum advertising policies are then found by solving a stochastic control problem with reflecting boundaries. Analytical results are obtained and interpreted to yield insights regarding a firm's risk behaviour and its optimal advertising policy.
Optimal control of current in a cathodic protection system: A numerical investigation
Authors: Zamani N. G. , Chuang J. M.
Published: July 2010

In this paper, the optimal control of current in an impressed cathodic protection system is considered. Such systems are routinely used for corrosion prevention. The analysis presented here enables the corrosion engineer to have a systematic way of determining the current output from a rectifier for complete protection. The boundary element method is employed for numerical calculations of the resulting coupled boundary value problems.
Generalized minimum variance control law revisited
Authors: Grimble M. J.
Published: July 2010

The generalized minimum variance control law is employed in many of the most successful self‐tuning control schemes. However, the control law was derived by using a single‐stage cost function where a conditional expectation operator was employed. This has limited our understanding of the operation of the control law and resulted in certain operational disadvantages. By rederiving the controller using a normal LQG approach but with a cost function of the same basic form, some of these deficiencies are mitigated. Moreover, the reason that the controller has poor stability characteristics on non‐minimum phase systems becomes apparent and it is shown that the magnitude of the error weighting term must be severely restricted in some problems if stability is to be maintained. Thus it may not be possible to limit error variance to the desired extent.
Design of decoupled optimal stochastic systems for low sensitivity to small time delays
Authors: Bamani Ali , Lee Gordon K. F. , Jin Lu
Published: July 2010

In this paper the problem of decoupling in the presence of time delays and external noise disturbances is addressed. By constructing a performance measure that incorporates trajectory sensitivity, a controller is formulated which decouples the overall system in spite of the time delay or noise sources. An example is provided to illustrate the approach and to demonstrate the effects of the choice of sensitivity weighting matrix on the state trajectory perturbation.
A Dynamic activity analysis for a monopolistic firm
Authors: Hartl Richard F.
Published: July 2010

A monopolistic firm is considered that can choose between two production activities: a capital‐intensive one and a labor‐intensive one. The successive stages of evolution of the firm are discussed for several alternative formulations of the objective functional. The effect of a minimum employment constraint is investigated and other sensitivity results are provided.
Linear quadratic self‐tuning control of a liquid‐liquid extraction column
Authors: Najim K. , Youlal H. , Irving E. , Najim M.
Published: July 2010

An application of a linear quadratic self‐tuning control approach to a pulsed liquid‐liquid extraction column is described. The control algorithm is derived from the minimization of a quadratic cost function. The resulting Riccati equation is iterated until the closed‐loop poles belong to a predefined stability domain included in the unit circle. Based upon the certainty equivalence principle, the adaptive control algorithm involves a parameter identification procedure and a feedback control law which uses the estimated parameters.

Several experiments are carried out on a pulsed liquid‐liquid extraction column. Such extractors are being increasingly used in several industries because they are not energy‐consuming and they lead to high product purity. The column considered has the same dimensions as those currently used in fine chemical processes. The control objective is to optimize the column behaviour. The selected control variables are the pulse frequency and the conductivity measured at the bottom of the column. The experiments have been carried out with a mixture of water and toluene. The physical model developed for the column is too complex to use for control purposes. To represent the complex behaviour of the column, a single‐input/single‐output discrete‐time linear model was adopted. The parameters in the model are estimated on‐line with normalized data. The forgetting factor is also adjusted to maintain a constant trace of the estimator gain matix.

The results obtained show the ability of this algorithm to improve the efficiency of the process considered. Finally, some details on practical implementation are provided.
On Verification of fuel‐optimal space trajectories
Authors: Vasudevan Gopal , Lutze F. H.
Published: July 2010

Candidate fuel‐optimal trajectories for rendezvous in space are obtained with a parameter optimization method. These trajectories, which may include a minimum radius constraint, are verified against necessary conditions for optimality. Necessary conditions are presented in the form of requirements on a primer vector and in terms of requirements on the jumps in the costates when the constraint is encountered. In addition, criteria due to Lion and Handelsmann indicate how to improve candidate trajectories which prove non‐optimal so that they become locally optimal. Numerical results are presented which show that the candidate solutions must be obtained to a high level of accuracy before primer vector tests are valid.
Dynamic suboptimal control of a heat pump/heat storage system
Authors: Zaheeruddin M. , Gourishankar V. G. , Rink R. E.
Published: July 2010

Dynamic suboptimal control of a heat pump/heat storage system, recovering heat from a ground source and supplying it to a building via a storage tank, is investigated when the utilities offer time‐of‐day energy price incentives. On the basis of the analytical solution to the periodic optimization problem,1 suboptimal trajectories for the general time‐varying case are developed and a method for dealing with transition trajectories from one day to the next is given. The transition trajectories are very close to the numerically generated optimal trajectories and are simple enough to be implemented on microprocessors by use of standard PI controllers.
Optimal synchronization of n identical double‐integral plants with identical inputs but different initial conditions
Authors: Unbehauen H. , Vakilzadeh I.
Published: July 2010

In this paper automatic error elimination between outputs of n identical double‐integral plants (K/s2) with different output initial conditions will be studied with two distinct objectives: (1) making all the identical steady‐state outputs to be the double integral of any common input x(t); (2) having all the identical steady‐state outputs track perfectly a reference input r(t). Thus fulfilment of objective (1), which can be viewed as a synchronization problem, commands that the whole MIMO system work on a closed‐loop principle during the transient time in order to eliminate the errors between the n outputs; and on an open‐loop basis during the steady‐state phase in order to preserve the operation of the plant transfer functions (i.e. double integration) upon their inputs x(t). We shall see that objective (1) can always be attained if, once and for all, the plants are interconnected through identical PD‐controllers (1 + Ts), no matter what form the common inputs x(t) may have. This is a far cry from the orthodox feedback control systems in which the type of input always plays a decisive role in selecting the appropriate controller. Having arranged the system for achievement of objective (1), we will show, with a unique technique, that objective (2) can be achieved through use of only one replaceable controller H(s), which operates on the difference between the reference input r(t) and any one of the n outputs. That is, each time r(t) is changed with the possible necessary change of controller H(s), we can make any number of outputs follow the reference input. This second objective can be considered as both synchronization and tracking, which in the text we shall refer to as tracking. We shall also show, without any alteration in the arrangements of our MIMO system, that objective (1) can also be achieved for identical plants of transfer functions [K/s2(Tfs + 1)]. Through two examples, various observations discussed in the text will be demonstrated. Finally, armed with our previous results for simple‐integral plants (K/s) and the results obtained in this paper, we shall briefly discuss triple‐integral plants (K/s3) and q‐integral plants (K/s(q)).
Optimal control of temperature and fuel consumption for soaking pits in a steel plant—a distributed parameter approach
Authors: Yang D. R. , Wang F. Y. , Chang K. S. , Lee Won‐Kyoo
Published: July 2010

An optimal control theory for a class of non‐linear distributed parameter control systems in the general setting involving more than one spatial co‐ordinate is developed for use on control of a typical soaking pit in a steel industry. The system is described by a set of non‐linear partial differential equations in multidimensional spatial co‐ordinates and non‐linear boundary conditions with time‐dependent boundary controls as well as a spatially independent parameter vector which is governed by its own set of dynamic equations. The set of necessary conditions for optimality obtained from the theoretical development is directly applied to the optimal heating control of the soaking pit with rectangular ingots. The numerical solution by iterations demonstrates the success of the technique and the algorithm leading to the optimal policy for heating control of a typical soaking pit with minimum fuel consumption.
On Existence of a nash equilibrium point in N‐person non‐zero sum stochastic jump differential games
Authors: Wernerfelt Birger
Published: July 2010

Using the technique of Wan and Davis, we give an existence theorem for a Nash equilibrium point in N‐person non‐zero sum stochastic jump differential games. It is shown that if the Nash condition (generalized Isaacs condition) holds there is a Nash equilibrium point in feedback strategies. We extend the results to other solution concepts and discuss applications and extensions.
Levels of empathy in undergraduate occupational therapy students
Authors: Brown Ted , Williams Brett , Boyle Malcolm , Molloy Andrew , McKenna Lisa , Molloy Liz , Lewis Belinda
Published: July 2010

Empathy is an important attribute for occupational therapists in establishing rapport and in better understanding their clients. However, empathy can be compromised by high workloads, personal stressors and pressures to demonstrate efficacy. Occupational therapists also work with patients from a variety of diagnostic groups. The objective of this study was to determine the extent of empathy and attitudes towards clients amongst undergraduate occupational therapy students at one Australian University. A cross‐sectional study was undertaken using a written survey of the Jefferson Scale of Physician Empathy (JSPE) and the Medical Condition Regard Scale. Overall, a strong level of empathy was reported amongst students. Four medical conditions that occupational therapists work with (stroke, cerebral palsy, traumatic brain injury and depression) were held in high regard. Substance abuse, however, was held in comparatively low regard. Overall, the year of study appeared to have no significant impact on the students' empathy. Despite having a lower reported empathy level than found in health professions from other studies using the JSPE, occupational therapy students were found to have a good level of empathy. Of concern, however, was the bias reported against the medical condition of substance abuse, highlighting that the there may be a need to reinforce that patients from this diagnostic group are equally deserving of quality care irrespective of their clinical condition. Recommendations for future research include completing a longitudinal study of occupational therapy students' empathy levels and investigating the empathy levels of occupational therapists working with different client groups. Limitations of the study include the convenience sampling of occupational therapy students enrolled at one university which limits the generalizability of the results to groups of participants with similar characteristics. Copyright © 2010 John Wiley & Sons, Ltd.
Ausflug in die Vergangenheit: Chinin und andere Chinaalkaloide 3. Teil : Vom Weg zur Totalsynthese der Chinolin‐Chinaalkaloide über die Herstellung besser wirksamer Malariamittel bis zur Erforschung der Indol‐Chinaalkaloide
Authors: Eiden Fritz
Published: July 2010

Anfang des 20. Jahrhunderts war die Konstitution der Chinolin‐Chinaalkaloide endgültig aufgeklärt worden (siehe 1. Teil). Im Laufe von Jahrzehnten hatten dann Vorstellungen von der räumlichen Struktur dieser Alkaloide Gestalt angenommen (siehe 2. Teil). Mit dem Entwicklungstempo der organischen Chemie wuchsen auch Wunsch und Möglichkeiten, Chinin durch Synthese zu gewinnen. Wieder war es vor allem Paul Rabe, der Pläne schmiedete und mit seinen Mitarbeitern erfolgversprechende Wege erkundete. 1931 hatte die Hamburger Arbeitsgruppe die schwierigste Etappe bewältigt: die erste Totalsynthese eines natürlichen Chinaalkaloids – des Dihydrochinins – war gelungen. Mit den dabei gewonnenen Erkenntnissen im Rucksack konnten dann gegen Ende des zweiten Weltkriegs Robert Burns Woodward und William v. E. Doering einen weiteren Gipfel besteigen.

Nicht vergessen werden sollten auch die zahlreichen Versuche, mit Chinin als Molekülmodell besser wirkende und einfacher strukturierte Malariamittel zu entwickeln; die Erfolge waren aufsehenerregend – wenn auch oft wegen der Resistenzentwicklung von Krankheitserregern nicht von Dauer.

Und schließlich gab es da noch die schon im 19. Jahrhundert aus Chinarinden isolierten Indol‐Chinaalkaloide, deren Konstitution, räumlicher Aufbau und synthetischer Zugang zu erforschen waren.
Adverse drug events in the outpatient setting: an 11‐year national analysis
Authors: Bourgeois Florence T. , Shannon Michael W. , Valim Clarissa , Mandl Kenneth D.
Published: July 2010

Purpose

Adverse drug events (ADEs) are a common complication of medical care resulting in high morbidity and medical expenditure. Population level estimates of outpatient ADEs are limited. Our objective was to provide national estimates and characterizations of outpatient ADEs and determine risk factors associated with these events.

Methods

Data are from the National Center for Health Statistics which collects information on patient visits to outpatient clinics and emergency departments throughout the United States. We examined visits between 1995 and 2005 and measured the national annual estimates of and risk factors for outpatient ADEs requiring medical treatment.

Results

The national annual number of ADE‐related visits was 4 335 990 (95%CI: 4 326 872–4 345 108). Visits for ADEs to outpatient clinics increased over the study period from 9.0 to 17.0 per 1000 persons (p‐value for trend < 0.001). In multivariate analyses, factors associated with ADE visits included patient age (OR: 2.13; 95%CI: 1.63–2.79 for 65 years and older), number of medications taken by patient (OR: 1.88; 95%CI: 1.58–2.25 for five medications or more), and female gender (OR: 1.51; 95%CI: 1.34–1.71). Overall, outpatient ADEs resulted in 107 468 (95%CI: 89 011–125 925) hospital admissions annually, with older patients at highest risk for hospitalization (p‐value for trend < 0.001).

Conclusions

Both patient age and polypharmacy use are risk factors for ADE‐related healthcare visits, which have substantially increased in outpatient clinics between 1995 and 2005. The incidence of ADEs has particularly increased among patients 65 years and older with as many as 1 in 20 persons seeking medical care for an ADE. Copyright © 2010 John Wiley & Sons, Ltd.
Cardiovascular safety of ADHD medications: rationale for and design of an investigator‐initiated observational study
Authors: Hennessy Sean , Schelleman Hedi , Daniel Gregory W. , Bilker Warren B. , Kimmel Stephen E. , Guevara James , Cziraky Mark J. , Strom Brian L.
Published: July 2010

Purpose

To describe the design and rationale of an investigator‐initiated observational study to examine the cardiovascular safety of the following commonly‐used medications to treat attention deficit hyperactivity disorder (ADHD): amphetamines, methylphenidate, and atomoxetine.

Methods

We are conducting an observational cohort study using data from five large Medicaid programs and the HealthCore Integrated Research Database (HIRDSM), which is derived from administrative data from commercial health plans. Our primary outcomes of interest are (1) sudden death/ventricular arrhythmia, (2) stroke, (3) myocardial infarction, and (4) stroke or myocardial infarction as a composite outcome. These claims diagnoses have been previously validated in adults, and the positive predictive value in children will be examined as part of this study. Secondary outcomes are (1) all‐cause death, (2) non‐suicide death, and (3) non‐accident death. All design decisions have been made to minimize bias toward the null. Based on our pilot data, we expect to have at least 90% power to detect a minimum detectable hazard ratio (HR) of 3.0 in children and adolescents who initiate an ADHD medication for each outcome of interest (except for MI, for which the expected minimum detectable HR is 7.9). The expected minimum detectable HR is 1.7 for each outcome for adult incident ADHD medication users.

Results

Forthcoming.

Conclusions

Potential limitations to this study include a low expected event rate in children and adolescents, potentially incomplete ascertainment of outcomes, and potential confounding by unmeasured variables. Nevertheless, this study will provide important information about the cardiovascular safety of ADHD medications. Copyright © 2010 John Wiley & Sons, Ltd.