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Integrators
Kinds of Integrators Selected AbstractsDevelopment of an Enzymic Time Temperature Integrator for Sterilization Processes Based on Bacillus licheniformis ,-amylase at Reduced Water ContentJOURNAL OF FOOD SCIENCE, Issue 1 2002Y.P. Guiavarc'h ABSTRACT: The thermal stability of Bacillus licheniformis ,-amylase at low moisture content was studied, based on isothermal experiments performed in a temperature range 113 to 125 °C. The thermal inactivation was monitored by measuring the decrease in thermal denaturation enthalpy and/or the decrease in enzymic activity on pnitrophenyl-,-D-maltoheptaoside, or on starch as a substrate. Based on enthalpy readings, an enzymic system with a z-value of 10.4 °C was observed when using a relative humidity of 81% at 4 °C. A theoretical study showed that this system could be used as a Time Temperature Integrator (TTI) to monitor the safety of sterilization processes of numerous food products. [source] Kinetic Parameter Estimation of Time-temperature Integrators Intended for Use with Packaged Fresh SeafoodJOURNAL OF FOOD SCIENCE, Issue 3 2004T. F. M ENDOZA ABSTRACT: The United States Food and Drug Administration (USFDA) considers any hermetically sealed package containing fresh seafood as a reduced oxygen package (ROP) if the oxygen transmission rate of the package is less than 10000 cm3/m2/d. USFDA's recent Import Alert nr 16-125 effectively bans the use of ROP for fresh seafood in the United States unless adequate temperature control and thermal history monitoring is used. Time-temperature integrators (TTI) were proposed as one potential method to satisfy this thermal monitoring requirement. Evaluation and selection of appropriate TTIs remains a difficult process for seafood manufacturers. Three commercially available TTIs (Vitsab M2-10, C2-10, and Fresh-Check TJ2) and 5 prototype TTIs (Avery Dennison) were evaluated for performance against the Skinner and Larkin (1998) botulinum toxin lag-time relationship. Isothermal treatments at 0°C, 5°C, 10°C, and 15°C were used to determine Arrhenius kinetic parameters of TTIs. Computer models were used to predict and compare actual TTI performance under dynamic thermal conditions. Results suggest that Vitsab M2-10 and Avery Dennison T126(2) and T126(4) TTIs may be used to predict safety of fresh seafood in ROP. [source] Delayed axonal pruning in the ant brain: A study of developmental trajectoriesDEVELOPMENTAL NEUROBIOLOGY, Issue 6 2009Marc A. Seid Abstract The coordination of neuronal maturation and behavioral development is a vital component of survival. The degradation of excessive axonal processes and neuronal networks is a ubiquitous developmental process. In Drosophila, a great portion of axonal pruning occurs during metamorphosis and transpires within hours after pupation. In contrast, we show, using EM-serial sectioning and 3D-reconstructions, that axonal pruning occurs after eclosion and over the course of 60 days in Cataglyphis albicans. Using the mushroom bodies of the brains of Cataglyphis, which have well-developed lip (olfactory integrator) and collar (visual integrator) regions, we show that axonal pruning is dependent upon the differences in the developmental trajectory of the lip and the collar brain regions and happens after eclosion. The elimination of the axonal boutons is most delayed in the collar region, where it is postponed until the ant has had extensive visual experience. We found that individual brain components within a single neuropil can develop at different rates that correlate with the behavioral ecology of these ants and suggest that glia may be mediating the axonal pruning. Our study provides evidence that adult ants may have relatively neotenous brains, and thus more flexibility, allowing them to neuronally adapt to the environment. This neoteny may, in part, explain the neural basis for age-dependent division of labor and the amazing behavioral flexibility exhibited by ants. © 2009 Wiley Periodicals, Inc. Develop Neurobiol, 2009 [source] Long-span seek control system for hard disk drive without mode-switchingELECTRICAL ENGINEERING IN JAPAN, Issue 3 2010Shinji Takakura Abstract In hard disk drives (HDD) there are two control modes: the head positioning control mode and the other is the seek control mode. In the head positioning control mode, a feedback controller is optimally designed to suppress disturbances. In the long-span seek mode, a velocity feedback control system is applied in order to move the heads fast. Thus, an HDD has multiple control systems, and the head is moved to the target position while changing from one control system to the other. However, changing the control system causes a discontinuous control signal, which activates the resonant mode of an actuator. Past methods can only decrease discontinuous control, and therefore a single control system that can be used for both a seek control mode and a head positioning control mode is necessary for a narrow track pitch. In the proposed method, the feedback controller is decomposed into an integrator and a phase compensator. The VCM model is updated by the output of the phase compensator, and the integrator and the output of the velocity feedback controller control the VCM. The validity of the proposed method was confirmed by numerical and experimental results using a miniature 2.5-inch hard disk drive. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 171(3): 51,60, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20935 [source] Intermediate frequency zero-crossing detection of filtered MSK based on irregular samplingEUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 7 2007Tobias Scholand Short range communication systems such as Bluetooth and DECT (Digital Enhanced Cordless Telecommunications) deploy Gaussian frequency shift keying (GFSK), which is a continuous phase modulation (CPM) scheme derived from minimum shift keying (MSK). Since these short range communication systems require low-cost transceiver structures, the development of appropriate receiver techniques has been a major research topic. Particularly, analogue limiter--discriminator--integrator (LDI) dump filtering techniques have received considerable attention. With the availability of digital signal processing (DSP), the digital implementation of LDI techniques has become increasingly attractive. In order to make LDI receivers more accessible, zero-crossing detection was proposed. First, the authors shall focus on the establishment of an appropriate mathematical discrete-time system model, taking bandlimiting receiver filters into account explicitly. This system model serves as the basis for the development of a multitude of digital zero-crossing detection techniques. Starting from this mathematical discrete-time system model, the authors shall focus on a novel, yet promising, approach to digital zero-crossing detection in the intermediate frequency domain, using irregular sampling instead of the commonly employed regular sampling. The novel detectors shall be termed zero-crossing decorrelation detectors (ZXDDs), because a decorrelating approach will be used. The authors shall present three different variants of the ZXDD. The performance of these ZXDD schemes has been analysed in simulations by the authors and obtained results shall be presented and compared to the performance of known LDI and zero-crossing detection based techniques. Copyright © 2007 John Wiley & Sons, Ltd. [source] Parameter sensitivity in finite element analysis with constitutive models of the rate typeINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 2 2006Wolfgang Fellin Abstract Non-linear soil,structure interactions are usually analysed using an incremental finite element approach. There a constitutive subroutine provides for each element the stress increment for a given strain increment. In geotechnical calculations, uncertainties in material parameters and initial conditions are abundant. Sensitivity analysis can be a first step to account for such uncertainties. Sensitivities of the system response with respect to material parameters and initial conditions can be calculated by differentiating the whole numerical scheme. It turns out that the essential information from the constitutive subroutine are the derivatives of the stress increment with respect to the strain increment, as well as the derivatives with respect to material parameters and all state variables involved in the problem. We propose a method to compute these quantities numerically for any constitutive model that can be written in rate form and for any suitable integrator of such a model. We further present a concise way to supply the output of the sensitivity analysis to the designing engineer. Our theoretical investigations are illustrated with element tests and with a typical geotechnical application. Copyright © 2005 John Wiley & Sons, Ltd. [source] A variationally consistent framework for the design of integrator and updates of generalized single step representations for structural dynamicsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Issue 8 2003R. Kanapady Abstract A variationally consistent framework leading to the concise design of both the ,integrator' and the associated ,updates' as related to the single step representations encompassing the so-called LMS methods for structural dynamics is described. The present paper shows for the first time, a consistent treatment involving both the ,integrator' and ,updates' that are inherent in the general context of designing the time integration process. Furthermore, the framework encompasses not only all the existing time integration algorithms that are dissipative and non-dissipative within the scope of LMS methods but also contains new optimal algorithms useful for practical applications,in the sense of accuracy, stability, numerical dissipation and dispersion, and overshoot characteristics of computational algorithms for time dependent problems encountered in structural dynamics. Copyright © 2003 John Wiley & Sons, Ltd. [source] Electron transport enhanced molecular dynamics for metals and semi-metals,INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 8-9 2010Reese E. Jones Abstract In this work we extend classical molecular dynamics by coupling it with an electron transport model known as the two temperature model. This energy balance between free electrons and phonons was first proposed in 1956 by Kaganov et al. but has recently been utilized as a framework for coupling molecular dynamics to a continuum description of electron transport. Using finite element domain decomposition techniques from our previous work as a basis, we develop a coupling scheme that preserves energy and has local control of temperature and energy flux via a Gaussian isokinetic thermostat. Unlike the previous work on this subject, we employ an efficient, implicit time integrator for the fast electron transport which enables larger stable time steps than the explicit schemes commonly used. A number of example simulations are given that validate the method, including Joule heating of a copper nanowire and laser excitation of a suspended carbon nanotube with its ends embedded in a conducting substrate. Published in 2010 by John Wiley & Sons, Ltd. [source] Lie-Poisson integrators: A Hamiltonian, variational approachINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 13 2010Zhanhua Ma Abstract In this paper we present a systematic and general method for developing variational integrators for Lie-Poisson Hamiltonian systems living in a finite-dimensional space ,,*, the dual of Lie algebra associated with a Lie group G. These integrators are essentially different discretized versions of the Lie-Poisson variational principle, or a modified Lie-Poisson variational principle proposed in this paper. We present three different integrators, including symplectic, variational Lie-Poisson integrators on G×,,* and on ,,×,,*, as well as an integrator on ,,* that is symplectic under certain conditions on the Hamiltonian. Examples of applications include simulations of free rigid body rotation and the dynamics of N point vortices on a sphere. Simulation results verify that some of these variational Lie-Poisson integrators are good candidates for geometric simulation of those two Lie-Poisson Hamiltonian systems. Copyright © 2009 John Wiley & Sons, Ltd. [source] Stability and accuracy analysis of a discrete model reference adaptive controller without and with time delayINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 9 2010Oreste S. Bursi Abstract Adaptive control techniques can be applied to dynamical systems whose parameters are unknown. We propose a technique based on control and numerical analysis approaches to the study of the stability and accuracy of adaptive control algorithms affected by time delay. In particular, we consider the adaptive minimal control synthesis (MCS) algorithm applied to linear time-invariant plants, due to which, the whole controlled system generated from state and control equations discretized by the zero-order-hold (ZOH) sampling is nonlinear. Hence, we propose two linearization procedures for it: the first is via what we term as physical insight and the second is via Taylor series expansion. The physical insight scheme results in useful methods for a priori selection of the controller parameters and of the discrete-time step. As there is an inherent sampling delay in the process, a fixed one-step delay in the discrete-time MCS controller is introduced. This results in a reduction of both the absolute stability regions and the controller performance. Owing to the shortcomings of ZOH sampling in coping with high-frequency disturbances, a linearly implicit L-stable integrator is also used within a two degree-of-freedom controlled system. The effectiveness of the methodology is confirmed both by simulations and by experimental tests. Copyright © 2009 John Wiley & Sons, Ltd. [source] Rigid body dynamics in terms of quaternions: Hamiltonian formulation and conserving numerical integrationINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 4 2009Peter Betsch Abstract In the present paper unit quaternions are used to describe the rotational motion of a rigid body. The unit-length constraint is enforced explicitly by means of an algebraic constraint. Correspondingly, the equations of motion assume the form of differential-algebraic equations (DAEs). A new route to the derivation of the mass matrix associated with the quaternion formulation is presented. In contrast to previous works, the newly proposed approach yields a non-singular mass matrix. Consequently, the passage to the Hamiltonian framework is made possible without the need to introduce undetermined inertia terms. The Hamiltonian form of the DAEs along with the notion of a discrete derivative make possible the design of a new quaternion-based energy,momentum scheme. Two numerical examples demonstrate the performance of the newly developed method. In this connection, comparison is made with a quaternion-based variational integrator, a director-based energy,momentum scheme, and a momentum conserving scheme relying on the discretization of the classical Euler's equations. Copyright © 2009 John Wiley & Sons, Ltd. [source] Parallel asynchronous variational integratorsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 3 2007Kedar G. Kale Abstract This paper presents a scalable parallel variational time integration algorithm for nonlinear elastodynamics with the distinguishing feature of allowing each element in the mesh to have a possibly different time step. Furthermore, the algorithm is obtained from a discrete variational principle, and hence it is termed parallel asynchronous variational integrator (PAVI). The underlying variational structure grants it outstanding conservation properties. Based on a domain decomposition strategy, PAVI combines a careful scheduling of computations with fully asynchronous communications to provide a very efficient methodology for finite element models with even mild distributions of time step sizes. Numerical tests are shown to illustrate PAVI's performance on both slow and fast networks, showing scalability properties similar to the best parallel explicit synchronous algorithms, with lower execution time. Finally, a numerical example in which PAVI needs ,100 times less computing than an explicit synchronous algorithm is shown. Copyright © 2006 John Wiley & Sons, Ltd. [source] Numerical study of an inviscid incompressible flow through a channel of finite lengthINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 12 2009Vasily N. Govorukhin Abstract A two-dimensional inviscid incompressible flow in a rectilinear channel of finite length is studied numerically. Both the normal velocity and the vorticity are given at the inlet, and only the normal velocity is specified at the outlet. The flow is described in terms of the stream function and vorticity. To solve the unsteady problem numerically, we propose a version of the vortex particle method. The vorticity field is approximated using its values at a set of fluid particles. A pseudo-symplectic integrator is employed to solve the system of ordinary differential equations governing the motion of fluid particles. The stream function is computed using the Galerkin method. Unsteady flows developing from an initial perturbation in the form of an elliptical patch of vorticity are calculated for various values of the volume flux of fluid through the channel. It is shown that if the flux of fluid is large, the initial vortex patch is washed out of the channel, and when the flux is reduced, the initial perturbation evolves to a steady flow with stagnation regions. Copyright © 2008 John Wiley & Sons, Ltd. [source] An implicit edge-based ALE method for the incompressible Navier,Stokes equations,INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 3 2003Richard W. Smith Abstract A new finite volume method for the incompressible Navier,Stokes equations, expressed in arbitrary Lagrangian,Eulerian (ALE) form, is presented. The method uses a staggered storage arrangement for the pressure and velocity variables and adopts an edge-based data structure and assembly procedure which is valid for arbitrary n-sided polygonal meshes. Edge formulas are presented for assembling the ALE form of the momentum and pressure equations. An implicit multi-stage time integrator is constructed that is geometrically conservative to the precision of the arithmetic used in the computation. The method is shown to be second-order-accurate in time and space for general time-dependent polygonal meshes. The method is first evaluated using several well-known unsteady incompressible Navier,Stokes problems before being applied to a periodically forced aeroelastic problem and a transient free surface problem. Published in 2003 by John Wiley & Sons, Ltd. [source] LS-DYNA and the 8:1 differentially heated cavityINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 8 2002Mark A. Christon Abstract This paper presents results computed using LS-DYNA's new incompressible flow solver for a differentially heated cavity with an 8:1 aspect ratio at a slightly super-critical Rayleigh number. Three Galerkin-based solution methods are applied to the 8:1 thermal cavity on a sequence of four grids. The solution methods include an explicit time-integration algorithm and two second-order projection methods,one semi-implicit and the other fully implicit. A series of ad hoc modifications to the basic Galerkin finite element method are shown to result in degraded solution quality with the most serious effects introduced by row-sum lumping the mass matrix. The inferior accuracy of a lumped mass matrix relative to a consistent mass matrix is demonstrated with the explicit algorithm which fails to obtain a transient solution on the coarsest grid and exhibits a general trend to under-predict oscillation amplitudes. The best results are obtained with semi-implicit and fully implicit second-order projection methods where the fully implicit method is used in conjunction with a ,smart' time integrator. Copyright © 2002 John Wiley & Sons, Ltd. [source] Adaptive control of stochastic nonlinear systems with uncontrollable linearizationINTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 7 2009Wang Qiang-de Abstract For a class of high-order stochastic nonlinear systems with uncontrollable linearization, this paper investigates the problem of adaptive global stability in probability. By using the tool of adaptive adding a power integrator, a feedback domination design approach is presented and a smooth controller is constructed. The closed-loop stochastic system is proved to be globally stable in probability and the states can be regulated to the origin almost surely. Copyright © 2008 John Wiley & Sons, Ltd. [source] Low power switched-current circuits with low sensitivity to the rise/fall time of the clockINTERNATIONAL JOURNAL OF CIRCUIT THEORY AND APPLICATIONS, Issue 5 2010Radek Rudnicki Abstract The switched-current (SI) technique permits realizing analog discrete-time circuits in standard digital CMOS technology. A very important property of the analog part of a system on a chip is the possibility it offers for realizing some functions of a digital circuit, but with reduced power consumption. In this paper, a low power SI integrator is presented. It is shown that an integrator consuming a fraction of a milliwatt can be designed in 0.35µm CMOS technology with the use of narrow transistor channels, and with the channel length as a design parameter. The impact of the rise/fall time of the clock signal on the integrator operation is observed. It is shown that this effect can be reduced when the proper switch dimensions are taken for the integrator. Analysis and measurements of the integrator noise are presented. The integrator was built with equal size transistors, yielding less sensitivity to variations in production parameters. An experimental chip in 0.35µm CMOS technology was fabricated, and measurements are compared with results obtained during analysis and simulations. In order to verify the properties of the designed integrator experimentally, a first-order filter is built with the use of elementary cells on the chip. Copyright © 2008 John Wiley & Sons, Ltd. [source] Realization of log-domain high-order transfer functions using first-order building blocks and complementary operatorsINTERNATIONAL JOURNAL OF CIRCUIT THEORY AND APPLICATIONS, Issue 1 2007Costas Psychalinos Abstract High-order log-domain filters could be easily designed by using the functional block diagram (FBD) representation of the corresponding linear prototype and a set of complementary operators. For this purpose, lossy and lossless integrator blocks have been already introduced in the literature. Novel first-order log-domain highpass and allpass filter configurations, which are fully compatible with the already published integrator blocks, are introduced in this paper. These are realized using integration and subtraction blocks or a novel differentiation configuration. As a result, a complete set of first-order building blocks would be available for synthesizing any arbitrary high-order transfer function. In order to verify the correct operation of the proposed structures, the performance of the introduced highpass filters was evaluated through simulation results. In addition, a fifth-order log-domain bandpass filter was designed and simulated using one of the introduced first-order highpass filter configurations. Copyright © 2006 John Wiley & Sons, Ltd. [source] The Actin Cytoskeleton and Signaling Network during Pollen Tube Tip GrowthJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 2 2010Ying Fu The organization and dynamics of the actin cytoskeleton play key roles in many aspects of plant cell development. The actin cytoskeleton responds to internal developmental cues and environmental signals and is involved in cell division, subcellular organelle movement, cell polarity and polar cell growth. The tip-growing pollen tubes provide an ideal model system to investigate fundamental mechanisms of underlying polarized cell growth. In this system, most signaling cascades required for tip growth, such as Ca2+ -, small GTPases- and lipid-mediated signaling have been found to be involved in transmitting signals to a large group of actin-binding proteins. These actin-binding proteins subsequently regulate the structure of the actin network, as well as the rapid turnover of actin filaments (F-actin), thereby eventually controlling tip growth. The actin cytoskeleton acts as an integrator in which multiple signaling pathways converge, providing a general growth and regulatory mechanism that applies not only for tip growth but also for polarized diffuse growth in plants. [source] Insulin inhibits extracellular regulated kinase 1/2 phosphorylation in a phosphatidylinositol 3-kinase (PI3) kinase-dependent manner in Neuro2a cellsJOURNAL OF NEUROCHEMISTRY, Issue 1 2003L. P. Van Der Heide Abstract Insulin signalling is well studied in peripheral tissue, but not in neuronal tissue. To gain more insight into neuronal insulin signalling we examined protein kinase B (PKB) and extracellular regulated kinase 1 and 2 (ERK1/2) regulation in serum-deprived Neuro2a cells. Insulin phosphorylated PKB in a dose-dependent manner but reduced phosphorylation of ERK1/2. Both processes were phosphatidylinositol 3-kinase (PI3K) dependent. Interestingly, blockade of PI3K in combination with insulin induced phosphorylation of ERK1/2. The phosphorylation of ERK1/2 could be blocked with a specific inhibitor of mitogen-activated protein/ERK kinase (MEK), suggesting that it was mediated through the highly conserved Ras,Raf,MEK,ERK1/2 pathway. Prolonged exposure to high concentrations of insulin resulted in a desensitized PI3K,PKB route. The insulin-induced inhibition of ERK1/2 phosphorylation was also diminished when the PI3K,PKB route was desensitized. Blockade of PI3K in combination with insulin, however, still resulted in an unaltered MEK-dependent phosphorylation of ERK1/2. We conclude that PI3K is an important integrator of insulin signalling in Neuro2a cells as it regulates activation of PKB and inhibition of ERK1/2, and is sensitive to the duration of the insulin stimulus. [source] Human Rights Barriers for Displaced Persons in Southern SudanJOURNAL OF NURSING SCHOLARSHIP, Issue 3 2009Carol Pavlish PhD Abstract Purpose: This community-based research explores community perspectives on human rights barriers that women encounter in a postconflict setting of southern Sudan. Methods: An ethnographic design was used to guide data collection in five focus groups with community members and during in-depth interviews with nine key informants. A constant comparison method of data analysis was used. Atlas.ti data management software facilitated the inductive coding and sorting of data. Findings: Participants identified three formal and one set of informal community structures for human rights. Human rights barriers included shifting legal frameworks, doubt about human rights, weak government infrastructure, and poverty. Conclusions: The evolving government infrastructure cannot currently provide adequate human rights protection, especially for women. The nature of living in poverty without development opportunities includes human rights abuses. Good governance, protection, and human development opportunities were emphasized as priority human rights concerns. Human rights framework could serve as a powerful integrator of health and development work with community-based organizations. Clinical Relevance: Results help nurses understand the intersection between health and human rights as well as approaches to advancing rights in a culturally attuned manner. [source] Using structuration theory to analyze knowledge and process management in a consortium: a case studyKNOWLEDGE AND PROCESS MANAGEMENT: THE JOURNAL OF CORPORATE TRANSFORMATION, Issue 2 2007Ping Gao Through a case study, this paper attempts to establish an argument that structuration theory is a suitable tool for analyzing the issue of knowledge and process management in a consortium. To do so, we first theoretically demonstrate that structuration theory can be linked with the theory of organizational knowledge creation, assuming that structure is a type of categorization of knowledge, and knowledge creation is a structuration process. We then use structuration theory to dissect a consortium designing mobile commerce services. The case study concludes that the structuration perspective enables researchers to expose the improvisatory mechanism of organizational knowledge creation, in which distributed tacit knowledge is crystallized into collective explicit knowledge. The empirical observation argues that a consortium should have a pre-project phase when a common vocabulary is developed and an integrator is introduced. The experience of our case consortium,that the white book has emerged as a tool of knowledge and process management,can be drawn upon by other cases. Copyright © 2007 John Wiley & Sons, Ltd. [source] No association between partial depopulation and Campylobacter spp. colonization of Dutch broiler flocksLETTERS IN APPLIED MICROBIOLOGY, Issue 3 2005A.D. Russa Abstract Aims:, To determine whether an association exists between partial depopulation of a flock and increased Campylobacter colonization in that flock. Methods and Results:, Data from 1737 flocks of two Dutch integrators were used. Flocks that experienced partial depopulation were defined as ,exposed' and those that did not as ,nonexposed'. Multivariable modelling was accomplished with, in addition to ,exposure', the independent variables ,age of broilers at slaughter' and ,season' to adjust for possible confounding. The response variable was ,Campylobacter colonization'. The odds ratio (OR) for partial depopulation for integrator A was 0·8 [95% CI (0·4, 1·8)]; for integrator B the OR = 0·8 [95% CI (0·5, 1·3)]. Age and season were confounders: the difference in Campylobacter status between exposed and nonexposed flocks of integrator A could be explained by both variables; for integrator B, only season was associated with Campylobacter status. Conclusions:, We found no significant association between partial depopulation and an increased risk of Campylobacter colonization among broiler flocks at final depopulation. Significance and Impact of the Study:, This study demonstrates that Campylobacter colonization in a broiler flock is not influenced by the partial depopulation of that flock. [source] A hybrid N -body code incorporating algorithmic regularization and post-Newtonian forcesMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 1 2008S. Harfst ABSTRACT We describe a novel N -body code designed for simulations of the central regions of galaxies containing massive black holes. The code incorporates Mikkola's ,algorithmic' chain regularization scheme including post-Newtonian terms up to PN2.5 order. Stars moving beyond the chain are advanced using a fourth-order integrator with forces computed on a GRAPE board. Performance tests confirm that the hybrid code achieves better energy conservation, in less elapsed time, than the standard scheme and that it reproduces the orbits of stars tightly bound to the black hole with high precision. The hybrid code is applied to two sample problems: the effect of finite- N gravitational fluctuations on the orbits of the S-stars, and inspiral of an intermediate-mass black hole into the Galactic Centre. [source] The effect of non-gravitational forces on the median inclination of short-period cometsMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2007David W. Hughes ABSTRACT The numbered Jupiter family comets (orbital periods P < 20 yr) have a median orbital inclination of about . In this paper, we integrate the orbits of these comets into the future, under the influence of both typical non-gravitational forces and planetary perturbation, using a Bulirsch,Stoer integrator. In the case where non-gravitational forces were not acting, the median inclination of those comets that remained on P < 20 yr orbits increased at the rate of (1.92 ± 0.12) × 10,3 deg yr,1 for the first 3600 yr of the integration. During this time the population of the original family decreases, such that the half-life is about 13 200 ± 800 yr. The introduction of non-gravitational forces slows down the rate of increase in inclination to a value of around (1.23 ± 0.16) × 10,3 deg yr,1. This rate of increase in inclination was found to be only weakly dependent on the non-gravitational parameters used during the integration. After a few thousand years, the rate of change in inclination decreases, and after 20 000 yr the inclinations of those initial Jupiter family members that still have orbits with P < 20 yr become constant at about , independent of whether non-gravitational forces are acting or not. The presently known Jupiter family of comets is losing members at the rate of one in every 67 yr. To maintain the family in equilibrium, Jupiter has to capture comets at a similar rate, and these captured comets have to be of low inclination to compensate for the pumping up of inclinations by gravitational perturbation. [source] Studies on heat processing and storage of seer fish curry in retort pouchesPACKAGING TECHNOLOGY AND SCIENCE, Issue 1 2002C. N. Ravi Shankar Abstract Seer fish in curry medium packed in locally manufactured retort pouches, having a three-layer configuration of thickness 12.5,µm polyester/12.5,µm aluminium foil/80,µm cast polypropylene was processed in a steam/air mixture over a pressure retort. About 210,g fish curry, having 110,g fish slices, was packed in a retort pouch of size 17,cm,×,15.5,cm, each fitted with a thermocouple. Time,temperature data were collected during heat processing using an Ellab data recorder FO and cook value integrator. The heat penetration characteristics were determined using a mathematical method. The fh value was 25,min with a FO value of 11.5 and cook value of 95,min. These samples remained in good condition for up to 24 months at room temperature. Copyright © 2002 John Wiley & Sons, Ltd. [source] Accelerating the coarse time-stepper for a lattice Boltzmann modelPROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2007Christophe Vandekerckhove The equation-free framework for multiscale computing is built around the central idea of a coarse time-stepper, which is an approximate time integrator for the macroscopic variables when only a microscopic simulator is available. In a previous paper, we studied the accuracy and stability of the coarse time-stepper when the microscopic simulator is a lattice Boltzmann model for one-dimensional diffusion. In this paper, we rely on these results to show how the coarse time-stepper can be accelerated using the recently proposed teleprojective method or the multistep state extrapolation method. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Nurturing and growing innovative start-ups: the role of policy as integratorR & D MANAGEMENT, Issue 2 2007Bart Clarysse Nurturing and growing innovative start-ups have become an important point on the political agenda. After the dotcom bubble, however, many financial schemes and incubation initiatives initiated, in the mid-nineties, were cancelled or down scaled. There was a consensus that innovative start-ups need more than just money. Networking and coaching were identified as additional needs. Besides this, there is a change in the intensity and nature of these needs during the different stages of the early life cycle. In this paper we make an in-depth study of three approaches to nurture and grow innovative start-ups. Each of these initiatives embeds in a very different national innovation system: Chalmers Innovation in Sweden and Anvar/Banque de Développement des PMEs in France, and Sitra's PreSeed Service in Finland. Each approach is compared in terms of its financing, networking, and coaching support, along the different stages of the start-up's life cycle. [source] Old Molecules for New Receptors: Trp(Nps) Dipeptide Derivatives as Vanilloid TRPV1 Channel BlockersCHEMMEDCHEM, Issue 4 2006Angeles Bonache Dr. Abstract The transient receptor potential vanilloid member 1 (TRPV1), an integrator of multiple pain-producing stimuli, is regarded nowadays as an important biological target for the discovery of novel analgesics. Here, we describe the first experimental evidence for the behavior of an old family of analgesic dipeptides, namely Xaa-Trp(Nps) and Trp(Nps)-Xaa (Xaa=Lys, Arg) derivatives, as potent TRPV1 channel blockers. We also report the synthesis and biological investigation of a series of new conformationally restricted Trp(Nps)-dipeptide derivatives with improved TRPV1/NMDA selectivity. Compound 15,b, which incorporates an N-terminal 2S -azetidine-derived Arg residue, was the most selective compound in this series. Collectively, a new family of TRPV1 channel blockers emerged from our results, although further modifications are required to fine-tune the potency/selectivity/toxicity balance. [source] Pathwise accuracy and ergodicity of metropolized integrators for SDEsCOMMUNICATIONS ON PURE & APPLIED MATHEMATICS, Issue 5 2010Nawaf Bou-Rabee Metropolized integrators for ergodic stochastic differential equations (SDEs) are proposed that (1) are ergodic with respect to the (known) equilibrium distribution of the SDEs and (2) approximate pathwise the solutions of the SDEs on finite-time intervals. Both these properties are demonstrated in the paper, and precise strong error estimates are obtained. It is also shown that the Metropolized integrator retains these properties even in situations where the drift in the SDE is nonglobally Lipschitz, and vanilla explicit integrators for SDEs typically become unstable and fail to be ergodic. © 2009 Wiley Periodicals, Inc. [source] | ||||||||||||||||||||||||||||||||||||||||||||||