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Loop
Kinds of Loop Terms modified by Loop Selected AbstractsThe Diagnosis of Cardiac Arrhythmias: A Prospective Multi-Center Randomized Study Comparing Mobile Cardiac Outpatient Telemetry Versus Standard Loop Event MonitoringJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 3 2007STEVEN A. ROTHMAN M.D. Introduction: Ambulatory electrocardiographic monitoring systems are frequently used in the outpatient evaluation of symptoms suggestive of a cardiac arrhythmia; however, they have a low yield in the identification of clinically significant but infrequent, brief, and/or intermittently symptomatic arrhythmias. The purpose of this study was to compare the relative value of a mobile cardiac outpatient telemetry system (MCOT) with a patient-activated external looping event monitor (LOOP) for symptoms thought to be due to an arrhythmia. Methods and Results: The study was a 17-center prospective clinical trial with patients randomized to either LOOP or MCOT for up to 30 days. Subjects with symptoms of syncope, presyncope, or severe palpitations who had a nondiagnostic 24-hour Holter monitor were randomized. The primary endpoint was the confirmation or exclusion of a probable arrhythmic cause of their symptoms. A total of 266 patients who completed the monitoring period were analyzed. A diagnosis was made in 88% of MCOT subjects compared with 75% of LOOP subjects (P = 0.008). In a subgroup of patients presenting with syncope or presyncope, a diagnosis was made in 89% of MCOT subjects versus 69% of LOOP subjects (P = 0.008). MCOT was superior in confirming the diagnosis of clinical significant arrhythmias, detecting such events in 55 of 134 patients (41%) compared with 19 of 132 patients (15%) in the LOOP group (P < 0.001). Conclusions: MCOT provided a significantly higher yield than standard cardiac loop recorders in patients with symptoms suggestive of a significant cardiac arrhythmia. [source] PERCUTANEOUS TRANSCATHETER CLOSURE OF PATENT DUCTUS ARTERIOSUS WITH AN AMPLATZER DUCT OCCLUDER USING RETROGRADE GUIDEWIRE-ESTABLISHED FEMORAL ARTERIOVENOUS LOOPCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 5-6 2008Jian-Fa Zhang SUMMARY 1The traditional antegrade wire-guided percutaneous transcatheter approach is not ideal in closing some types of patent ductus arteriosus (PDA) with abnormal morphology. The aim of the present study was to evaluate the efficacy of a retrograde wire-guided transcatheter approach for closure of some types of PDA using the Amplatzer duct occluder (ADO). 2Nineteen patients with abnormal PDA morphology, including a smaller ostium of the side of the pulmonary artery compared with the side of the descending aorta, severe calcification or tortuosity, were included in the present study. In these patients, after the antegrade approach failed to cross a wire from the pulmonary artery via the PDA to the descending aorta, a retrograde guidewire was passed through the PDA in the opposite direction, from the descending aorta to the pulmonary artery, to establish a femoral arteriovenous loop that assisted the deployment of the ADO in all 19 patients. The size of the PDA, as determined by angiography, was 3.1 ± 1.1 mm and the diameter of the ADO selected was 6.5 ± 1.5 mm. 3In 16 cases, systolic murmur disappeared after the procedure. Systolic murmur (less than Grade II) and angiographic residual shunt remained in three cases immediately after the procedure, but disappeared 1 month later. Mean pulmonary arterial pressure decreased from 33 ± 8 to 22 ± 4 mmHg in all 19 patients (P < 0.01). There were no complications during or after the procedure. 4The retrograde wire-guided technique offers an alternative approach to facilitate closure of a PDA that cannot be achieved by traditional antegrade wire-guided methods due to morphological abnormalities in the PDA. [source] Interruption and Imagination in Curriculum and Pedagogy, or How to Get Caught Inside a Strange LoopCURRICULUM INQUIRY, Issue 3 2010RUBÉN A. GAZTAMBIDE-FERNÁNDEZ First page of article [source] Myosin diversity in the diatom Phaeodactylum tricornutum,CYTOSKELETON, Issue 3 2010Matthew B. Heintzelman Abstract This report describes the domain architecture of ten myosins cloned from the pennate diatom Phaeodactylum tricornutum. Several of the P. tricornutum myosins show similarity to myosins from the centric diatom Thalassiosira pseudonana as well as to one myosin from the oomycete Phytophthora ramorum. The P. tricornutum myosins, ranging in size from 126 kDa to over 250 kDa, all possess the canonical head, neck and tail domains common to most myosins, though variations in each of these domains is evident. Among the features distinguishing several of the diatom myosin head domains are N-terminal SH3-like domains, variations in or near the P-loop and Loop 1 regions close to the nucleotide binding pocket, and extended converter domains. Variations in the length of the neck domain or lever arm, defined by the light chain-binding IQ motifs, are apparent with the different diatom myosins predicted to contain from one to nine IQ motifs. Protein domains found within the P. tricornutum myosin tails include regions of coiled-coil structure, ankyrin repeats, CBS domain pairs, a PB1 domain, a kinase domain and a FYVE-finger motif. As many of these features have never before been characterized in myosins of any type, it is likely that these new diatom myosins will expand the repertoire of known myosin behaviors. © 2010 Wiley-Liss, Inc. [source] Human Bone Cell Hyperpolarization Response to Cyclical Mechanical Strain Is Mediated by an Interleukin-1, Autocrine/Paracrine LoopJOURNAL OF BONE AND MINERAL RESEARCH, Issue 9 2000D. M. Salter Abstract Mechanical stimuli imparted by stretch, pressure, tension, fluid flow, and shear stress result in a variety of biochemical responses important in bone (re)modeling. The molecules involved in the recognition and transduction of mechanical stimuli that lead to modulation of bone cell function are not yet fully characterized. Cyclical pressure-induced strain (PIS) induces a rapid change in membrane potential of human bone cells (HBC) because of opening of membrane ion channels. This response is mediated via integrins and requires tyrosine kinase activity and an intact actin cytoskeleton. We have used this electrophysiological response to further study the signaling events occurring early after mechanical stimulation of HBC. Stimulation of HBC at 0.33Hz PIS, but not 0.104 Hz PIS, results in the production of a transferable factor that induces membrane hyperpolarization of unstimulated HBC. The production of this factor is inhibited by antibodies to ,1-integrin. Interleukin-1, (IL-1,) and prostaglandin E2 (PGE2) were identified as candidate molecules for the transferable factor as both were shown to induce HBC hyperpolarization by opening of small conductance calcium-activated potassium channels, the means by which 0.33 Hz PIS causes HBC hyperpolarization. Antibodies to IL-1,, but not other cytokines studied, inhibit the hyperpolarization response of HBC to 0.33 Hz PIS. Comparison of the signaling pathways required for 0.33 Hz PIS and IL-1,-induced membrane hyperpolarization shows that both involve the phospholipase C/inositol triphosphate pathway, protein kinase C (PKC), and prostaglandin synthesis. Unlike 0.33 Hz PIS-induced membrane hyperpolarization, IL-1,-induced hyperpolarization does not require tyrosine kinase activity or an intact actin cytoskeleton. These studies suggest that 0.33 Hz PIS of HBC induces a rapid, integrin-mediated, release of IL-1, with a subsequent autocrine/paracrine loop resulting in membrane hyperpolarization. IL-1, production in response to mechanical stimuli is potentially of importance in regulation of bone (re)modeling. [source] Interactions Between Extracellular Stimuli and Excitation Waves in an Atrial Reentrant LoopJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 10 2003CHAD R. JOHNSON B.S.E. Introduction: The interactions between extracellular stimuli and excitation waves propagating in a reentrant loop are a complex function of stimulus parameters, structural properties, membrane state, and timing. Here the goal was a comprehensive understanding of the mechanisms and frequencies of the major interactions between the advancing excitation wave and a single extracellular stimulus, separated from issues of anatomic or geometric complexity. Methods and Results: A modernized computer model of a thin ring of uniform tissue that included a pair of extracellular stimulus electrodes (anode/cathode) was used to model one-dimensional cardiac reentry. Questions and results included the following: (1) What are the major interactions between a stimulus and the reentrant propagation wave, and are they induced near the cathode or near the anode; and, for each interaction, what are the initiating amplitude range and timing interval? At the cathode, the well-known mechanism of retrograde excitation terminated reentry; changes in timing or amplitude produced double-wave reentry or phase reset. At the anode, termination occurred at different cells depending on stimulus amplitude. (2) Relatively how often did termination occur at the anode? For most stimulus amplitudes, termination occurred more often at the anode than at the cathode, although not always at the same cell. (3) With random timing, what is the probability of terminating reentry? Stimulation for 5 msec terminated reentry with a probability from 0% to approximately 10%, as a function of increasing stimulus amplitude. Conclusion: A single extracellular stimulus can initiate major changes in reentrant excitation via multiple mechanisms, even in a simple geometry. Termination of reentry, phase shifts, or double-wave reentry each occurs over well-defined ranges of stimulus amplitude and timing. (J Cardiovasc Electrophysiol, Vol. 14, pp. ***-***, October 2003) [source] Closing the Loop and Honing Our ToolsJOURNAL OF INDUSTRIAL ECOLOGY, Issue 4 2001Reid Lifset [source] Double Hysteresis Loop and Aging Effect in K0.5Na0.5NbO3,K5.4Cu1.3Ta10O9 Lead-Free CeramicsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 6 2009Dunmin Lin In this work, the double-loop-like characteristics of K0.5Na0.5NbO3+x mol% K5.4Cu1.3Ta10O9 ceramic and its relationships with the transition temperature, aging, and switching have been investigated. Our results reveal that the phase transition temperature is an important parameter determining the aging requirement for the ceramics to exhibit the double-loop-like characteristics. For a ceramic with a high transition temperature, e.g. the ceramic with x=0.75 (tetragonal,orthorhombic phase temperature ,206°C), the vacancies can migrate during the crystal transformation and settle in a distribution with the same symmetry as the crystal after the transformation. As a result, defect dipoles along the polarization direction are formed and provide restoring forces to reverse the switched polarizations, and thus producing a double polarization hysteresis (P,E) loop. On the other hand, aging is required for a ceramic with a low transition temperature, e.g. aging at 80°C for 30 days is required for the ceramic with x=1.5 (transition temperature ,175°C). Our results also reveal that the defect dipoles can be switched under a slow-switching electric field (<1 Hz) or at high temperatures (>100°C), thus leading to an opening of the double P,E loop. [source] Deep H, imagery of the Eridanus shellsMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 1 2001P. Boumis A deep H, image of interlocking filamentary arcs of nebulosity has been obtained with a wide-field (,30° diameter) narrow-band filter camera combined with a charge-coupled device as a detector. The resultant mosaic of images, extending to a galactic latitude of ,65°, has been corrected for field distortions and had galactic coordinates superimposed on it to permit accurate correlations with the most recent H i (21 cm), X-ray (0.75 keV) and FIR (IRAS 100 ,m) maps. Furthermore, an upper limit of 0.13 arcsec yr,1 to the expansion proper motion of the primary 25° long nebulous arc has been obtained by comparing a recent H, image obtained with the San Pedro Martir telescope of its filamentary edge with that on a Palomar Observatory Sky Survey E plate obtained in 1951. It is concluded that these filamentary arcs are the superimposed images of separate shells (driven by supernova explosions and/or stellar winds) rather than the edges of a single ,superbubble' stretching from Barnard's Arc (and the Orion Nebula) to these high galactic latitudes. The proper motion measurement argues against the primary H,-emitting arc being associated with the giant radio loop (Loop 2) except in extraordinary circumstances. [source] First Cytoplasmic Loop of Glucagon-like Peptide-1 Receptor Can Function at the Third Cytoplasmic Loop Position of Rhodopsin,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 4 2008Takahiro Yamashita G protein-coupled receptors (GPCRs) are classified into several families based on their amino acid sequences. In family 1, GPCRs such as rhodopsin and adrenergic receptor, the structure,function relationship has been extensively investigated to demonstrate that exposure of the third cytoplasmic loop is essential for selective G protein activation. In contrast, much less is known about other families. Here we prepared chimeric mutants between Gt-coupled rhodopsin and Gi/Go- and Gs-coupled glucagon-like peptide-1 (GLP-1) receptor of family 2 and tried to identify the loop region that functions at the third cytoplasmic loop position of rhodopsin. We succeeded in expressing a mutant having the first cytoplasmic loop of GLP-1 receptor and found that this mutant activated Gi and Go efficiently but did not activate Gt. Moreover, the rhodopsin mutant having the first loop of Gs-coupled secretin receptor of family 2 decreased the Gi and Go activation efficiencies. Therefore, the first loop of GLP-1 receptor would share a similar role to the third loop of rhodopsin in G protein activation. This result strongly suggested that different families of GPCRs have maintained molecular architectures of their ancestral types to generate a common mechanism, namely exposure of the cytoplasmic loop, to activate peripheral G protein. [source] Interaction Between N-terminal Loop and , -Scaffold of Photoactive Yellow Protein,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 4 2008Miki Harigai During the photoreaction cycle of photoactive yellow protein (PYP), a physiologically active intermediate (PYPM) is formed as a consequence of global protein conformational change. Previous studies have demonstrated that the photocycle of PYP is regulated by the N-terminal loop region, which is located across the central , -sheet from the p -coumaric acid chromophore. In this paper, the hydrophobic interaction between N-terminal loop and , -sheet was studied by characterizing PYP mutants of the hydrophobic residues. The rate constants and structural changes of the photocycle of L15A and L23A possibly participating in such an interaction were more similar to wild-type than F6A, showing that the CH/, interaction between Phe6 and Lys123 is the most essential as reported previously. To better understand the interactions between N-terminal tail and , -sheet of PYP, Phe6 and Phe121 were replaced by Cys and linked by a disulfide bond. Since the photocycle kinetics, structural change and thermal stability of F6C/F121C were similar to F6A, the CH/, interaction between Phe6 and Lys123 is not substitutable. It is likely that the detachment of position 6 from position 123 substantially alters the nature of PYP. [source] Out of the Loop: Why Research Rarely Reaches Policy Makers and the Public and What Can be DoneBIOTROPICA, Issue 5 2009Patricia Shanley ABSTRACT Most of the world's population that derives their livelihoods or part of their livelihoods from forests are out of the information loop. Exclusion of public users of natural resources from access to scientific research results is not an oversight; it is a systemic problem that has costly ramifications for conservation and development. Results of a survey of 268 researchers from 29 countries indicate that institutional incentives support the linear, top-down communication of results through peer-reviewed journal articles, which often guarantees positive performance measurement. While the largest percentage of respondents (34%) ranked scientists as the most important audience for their work, only 15 percent of respondents considered peer-reviewed journals effective in promoting conservation and/or development. Respondents perceived that local initiatives (27%) and training (16%) were likely to lead to success in conservation and development; but few scientists invest in these activities. Engagement with the media (5%), production of training and educational materials (4%) and popular publications (5%) as outlets for scientific findings was perceived as inconsequential (<14%) in measuring scientific performance. Less than 3 percent of respondents ranked corporate actors as an important audience for their work. To ensure science is shared with those who need it, a shift in incentive structures is needed that rewards actual impact rather than only ,high-impact' journals. Widely used approaches and theoretical underpinnings from the social sciences, which underlie popular education and communication for social change, could enhance communication by linking knowledge and action in conservation biology. [source] Incorporation of Dynamic Flexibility in the Design of a Methanol Synthesis Loop in the Presence of Catalyst DeactivationCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 1 2008P. Parvasi Abstract A typical methanol loop reactor is analyzed in this study. All basic equipment in the Lurgi-type methanol loop is included in the proposed model. A detailed dynamic model described by a set of ordinary differential and algebraic equations is developed to predict the behavior of the overall process. The model is validated against plant data. A new deactivation model is proposed and its parameters are estimated using daily plant data. The interesting feature of this model is that it incorporates the effect of carbon dioxide and carbon monoxide on the catalyst deactivation. Using the model, the effect of various factors to compensate for the reduction of production rate due to catalyst deactivation has been examined. Some improvements can be achieved by adjusting the operating conditions. Finally, a strategy is proposed for prevention of reduced production due to catalyst deactivation. [source] Incorporation of Flexibility in the Design of a Methanol Synthesis Loop in the Presence of Catalyst DeactivationCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 6 2003M.R. Rahimpour Abstract This paper presents the incorporation of process flexibility into a methanol synthesis loop operating under catalyst deactivation. A design methodology is discussed with regard to catalyst deactivation, and some limitations are identified. In the current flexibility study the size of the reactor and recycle ratio have been fixed. Attempts to maintain methanol production at the rates observed with fresh catalyst included increased pressure, increased make up gas flow rate, and the injection of carbon dioxide into the make up gas at optimized inlet temperature. In order to provide flexibility and produce a design compatible with increased production rates, the effect of interrelating equipment had to be considered. As a result of catalyst deactivation, an increased flow rate is necessary and the altered process streams entering the preheater disturb the reactor inlet temperature. These issues should be considered in the design stage and may be resolved by the flexible designs presented. [source] A Large Thermal Hysteresis Loop Produced by a Charge-Transfer Phase Transition in a Rubidium Manganese Hexacyanoferrate.CHEMINFORM, Issue 42 2004Hiroko Tokoro Abstract For Abstract see ChemInform Abstract in Full Text. [source] International Organizations in Transfer of Infectious Diseases: Iterative Loops of Adoption, Adaptation, and MarketingGOVERNANCE, Issue 2 2004Gill Walt Over the past few years increasing attention has been given to the role of international organizations in the diffusion of policy ideas and promotion of particular macro-level policies. Much of the attention has been on the ideological driving forces behind such policies, and on the extent to which the policies are externally imposed. There has been limited discussion on the bread-and-butter, technical policies of international organizations, and how they devise, adopt, adapt, and then promote what come to be seen as policies of global "best practice." This paper seeks to redress this gap by looking at the process of transfer of two infectious disease policies between international and national levels. It demonstrates that international organizations play different roles in policy transfer at particular stages in the process. The paper suggests that health policy transfer is a long adaptive process, made up of several iterative loops, as research and clinical practices developed in one or more countries are adopted, adapted, and taken up by international organizations which then mobilize support for particular policies, market, and promote them. Assumptions that new ideas about policies flow "rationally" into existing decision making are challenged by the processes analyzed here. Policy transfer, given the experience of these infectious diseases policies, goes through separate, "bottom-up," research-oriented, and "top-down" marketing-oriented loops. Individuals and different configurations of networks play key roles linking these loops. In the process, complex, context-specific policies are repackaged into simplified guidelines for global best practice, leading to considerable contestation within the policy networks. [source] Satellite rural communications: telephony and narrowband networksINTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 5 2005Roberto Conte Abstract Rural communications are important for large and developing countries, and telecommunications systems have been implemented depending upon the available technology at the time. Rural users do not generate the same amount of revenue as urban users do, thus lowering incentives for rural telecommunications investment with service to those regions delayed as long as possible. Voice and data communications are essential to the economic development of a region, and it has been shown that traffic increases rapidly as soon as the service is available. Satellite-based digital networks provide efficient long-distance service to rural communities at lower cost than similar land-based wired networks with acceptable quality. Small earth stations along with Wireless Local Loops can provide both local and long-distance service efficiently and at low cost, offering digital multimedia services on a global scale. This paper focuses on the description of different narrowband technologies used to service rural communities, namely basic telephone and low-bit-rate data (<64 kbps) applications through the use of satellite and terrestrial wireless systems. A basic network economic planning description is presented, and important parameters such as satellite network size, topology and multiple access are identified in order to improve the process of effective and cost-efficient rural communications network design. Copyright © 2005 John Wiley & Sons, Ltd. [source] Dislocation Loops in Pressureless-Sintered Undoped BaTiO3 CeramicsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 7 2006Yu-Chuan Wu Dislocation loops in pressureless-sintered undoped BaTiO3 ceramics have been analyzed by transmission electron microscopy. The Burgers vector of the loops and its sense b=+1/2[010] were determined using the g·b=0 invisibility criteria, combined with the inside,outside contrast technique using (g·b)sg>0 or<0, keeping the deviation parameter sg>0. The edge-vacancy nature was further ascertained by determining the loop habit plane normal n=[010]. Weak-beam dark-field imaging reveals that loops contained no stacking fault fringes; they are edge-vacancy partial dislocation loops lying in {020} or {010} where parts of the TiO2 or BaO layer are vacant. It is suggested that the extrinsic defects of both cations and oxygen vacancies generated by non-stoichiometry have condensed during sintering in air and are responsible for the formation of such vacancy loops. [source] Dissociation of the ,001, Dislocations and Their Interactions with Dislocation Loops in Tetragonal BaTiO3JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 5 2006Shun-Yu Cheng Dislocations in pressureless-sintered BaTiO3 ceramics have been analyzed using transmission electron microscopy. Subjected to effective sintering stresses, dislocations were generated and multiplied in plastically deformed BaTiO3 crystals by the Frank,Read mechanism from both single- and double-ended sources. This is represented by dislocations encompassing a series of square-like borders that shared a common center. All border dislocations exhibited the characteristic scallop shape. True dislocation line directions (u) were determined by trace analysis and Burgers vectors (b) by contrast analysis for the dislocations dissociated from b=,001, into two half-partials following the type (I) reaction ofby climb on {001}. Dislocation interactions between the main dislocations created from plastic deformation and dislocation loops of b=,100, or ,110, forming condensation of intrinsic Schottky vacancies were also found to obey the type (IV) reaction of, the type (V) reactions of. Migrating dislocations and loops interacting mutually in several stages, illustrated schematically, before arriving at the configuration described by types (IV) and (V) were observed and discussed. [source] Phase Field Simulations of Hysteresis and Butterfly Loops in Ferroelectrics Subjected to Electro-Mechanical Coupled LoadingJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 2 2006A. K. Soh Two-dimensional computer simulations of ferroelectric polarization switching have been performed using the phase field simulation model developed by employing the time-dependent Ginsburg,Landau equations. The bulk-free energy, polarization gradient energy, long-range dipole,dipole electrostatic interactions, and elastic energy were taken into account in the above-mentioned simulations. The influences of electric,mechanical coupled loading on the hysteresis and butterfly loops were studied. The results showed that the coupled electro-mechanical loading could change both the coercive field of ferroelectric materials and the symmetry of hysteresis and butterfly loops. [source] Comment on: Microsurgical Arterovenous Loops and Biological Templates: A Novel In Vivo Chamber for Tissue EngineeringMICROSURGERY, Issue 3 2008Elias Polykandriotis M.D. [source] Active TEM-1 ,-lactamase mutants with random peptides inserted in three contiguous surface loopsPROTEIN SCIENCE, Issue 10 2006Pascale Mathonet Abstract Engineering of alternative binding sites on the surface of an enzyme while preserving the enzymatic activity would offer new opportunities for controlling the activity by binding of non-natural ligands. Loops and turns are the natural substructures in which binding sites might be engineered with this purpose. We have genetically inserted random peptide sequences into three relatively rigid and contiguous loops of the TEM-1 ,-lactamase and assessed the tolerance to insertion by the percentage of active mutants. Our results indicate that tolerance to insertion could not be correlated to tolerance to mutagenesis. A turn between two ,-strands bordering the active site was observed to be tolerant to random mutagenesis but not to insertions. Two rigid loops comprising rather well-conserved amino acid residues tolerated insertions, although with some constraints. Insertions between the N-terminal helix and the first ,-strand generated active libraries if cysteine residues were included at both ends of the insert, suggesting the requirement for a stabilizing disulfide bridge. Random sequences were relatively well accommodated within the loop connecting the final ,-strand to the C-terminal helix, particularly if the wild-type residue was retained at one of the loops' end. This suggests two strategies for increasing the percentage of active mutants in insertion libraries. The amino acid distribution in the engineered loops was analyzed and found to be less biased against hydrophobic residues than in natural medium-sized loops. The combination of these activity-selected libraries generated a huge library containing active hybrid enzymes with all three loops modified. [source] A programming environment for behavioural animationCOMPUTER ANIMATION AND VIRTUAL WORLDS (PREV: JNL OF VISUALISATION & COMPUTER ANIMATION), Issue 5 2002Frédéric Devillers Abstract Behavioural models offer the ability to simulate autonomous agents like organisms and living beings. Psychological studies have shown that human behaviour can be described by a perception,decision,action loop, in which the decisional process should integrate several programming paradigms such as real time, concurrency and hierarchy. Building such systems for interactive simulation requires the design of a reactive system treating flows of data to and from the environment, and involving task control and preemption. Since a complete mental model based on vision and image processing cannot be constructed in real time using purely geometrical information, higher levels of information are needed in a model of the virtual environment. For example, the autonomous actors of a virtual world would exploit the knowledge of the environment topology to navigate through it. Accordingly, in this paper we present our programming environment for real-time behavioural animation which is compounded of a general animation and simulation platform, a behavioural modelling language and a scenario-authoring tool. Those tools has been used for different applications such as pedestrian and car driver interaction in urban environments, or a virtual museum populated by a group of visitors. Copyright © 2002 John Wiley & Sons, Ltd. [source] An educational tool for controlling of SRMCOMPUTER APPLICATIONS IN ENGINEERING EDUCATION, Issue 4 2008Tuncay Yigit Abstract This article introduces an educational tool for a switched reluctance motor (SRM) drive system. It is prepared for undergraduate and graduate level students. Classical PI and Genetic PI controllers are used in SRM drive system. The Genetic PI controller was applied to the speed loop, replacing the classical PI controller. The tool software was implemented using C++ Builder on a PC. It has flexible structure and graphical interface. The students can be easily establishing a thorough understanding of both classical PI and genetic PI controller for a SRM drive system. The education tool allowed the student to interact with the SRM drive system and it is using controllers. Then it is responses on a dynamic and instantaneous basis under different operating conditions. © 2008 Wiley Periodicals, Inc. Comput Appl Eng Educ 16: 268,279, 2008; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae20148 [source] Hierarchical Vortex Regions in Swirling FlowCOMPUTER GRAPHICS FORUM, Issue 3 2009Christoph Petz Abstract We propose a new criterion to characterize hierarchical two-dimensional vortex regions induced by swirling motion. Central to the definition are closed loops that intersect the flow field at a constant angle. The union of loops belonging to the same area of swirling motion defines a vortex region. These regions are disjunct but may be nested, thus introducing a spatial hierarchy of vortex regions. We present a parameter free algorithm for the identification of these regions. Since they are not restricted to star- or convex-shaped geometries, we are able to identify also intricate regions, e.g., of elongated vortices. Computing an integrated value for each loop and mapping these values to a vortex region, introduces new ways for visualizing or filtering the vortex regions. Exemplary, an application based on the Rankine vortex model is presented. We apply our method to several CFD datasets and compare our results to existing approaches. [source] Operative Platform Applied to Building AutomationCOMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 1 2009Joăo Figueiredo This structure is composed by three interrelated levels: the Operational level,where the field equipment is controlled, the Inter-Active level,where inhabitants communicate the building their preferences regarding control variables (lights, temperature, etc.), and the higher-level control, the Overall Building Well-Being Model, which manages the global building, taking into account the optimization of the inhabitants preferences, constrained by the available resources. At this third level, the inter-building communication is available. Each building has the capability to communicate with its neighbors, informing about fires, floods, security problems, power consumption expectations, and so on. This article implements one of the three above-referred interrelated control levels: the Operational-level control. This operative platform is structured over a cascade hierarchical control architecture where inner loops are performed by local PLCs (Programmable Logic Controllers), and the outer loop is managed by a centralized SCADA system (Supervisory Control and Data Acquisition) that interacts with the entire PLC network. The lower-level control loop assures high processing velocity tasks, the upper-level control loop updates the local references, knowing the complete system state. This operative model is tested on two prototypes, where all instrumentation in place is controlled by the industrial PLC network. Both prototypes worked perfectly showing the huge potential of communication systems between distributed processes. These communication systems allow intelligent centralized algorithms to manage decision-making problems in real-time environments. The system presented in this article combines several technologies (local PLCs, SCADA systems, and network communications) to reach the goal of efficient management of intelligent buildings. [source] Object combining: a new aggressive optimization for object intensive programsCONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 5-6 2005Ronald Veldema Abstract Object combining tries to put objects together that have roughly the same life times in order to reduce strain on the memory manager and to reduce the number of pointer indirections during a program's execution. Object combining works by appending the fields of one object to another, allowing allocation and freeing of multiple objects with a single heap (de)allocation. Unlike object inlining, which will only optimize objects where one has a (unique) pointer to another, our optimization also works if there is no such relation. Object inlining also directly replaces the pointer by the inlined object's fields. Object combining leaves the pointer in place to allow more combining. Elimination of the pointer accesses is implemented in a separate compiler optimization pass. Unlike previous object inlining systems, reference field overwrites are allowed and handled, resulting in much more aggressive optimization. Our object combining heuristics also allow unrelated objects to be combined, for example, those allocated inside a loop; recursive data structures (linked lists, trees) can be allocated several at a time and objects that are always used together can be combined. As Java explicitly permits code to be loaded at runtime and allows the new code to contribute to a running computation, we do not require a closed-world assumption to enable these optimizations (but it will increase performance). The main focus of object combining in this paper is on reducing object (de)allocation overhead, by reducing both garbage collection work and the number of object allocations. Reduction of memory management overhead causes execution time to be reduced by up to 35%. Indirection removal further reduces execution time by up to 6%. Copyright © 2005 John Wiley & Sons, Ltd. [source] EXTENDING SOCIAL DISORGANIZATION THEORY: MODELING THE RELATIONSHIPS BETWEEN COHESION, DISORDER, AND FEAR,CRIMINOLOGY, Issue 2 2001FRED E. MARKOWITZ In this study, we build on recent social disorganization research, estimating models of the relationships between disorder, burglary, cohesion, and fear of crime using a sample of neighborhoods from three waves of the British Crime Survey. The results indicate that disorder has an indirect effect on burglary through fear and neighborhood cohesion. Although cohesion reduces disorder, nonrecursive models show that disorder also reduces cohesion. Part of the effect of disorder on cohesion is mediated by fear. Similar results are obtained in nonrecursive burglary models. Together, the results suggest a feedback loop in which decreases in neighborhood cohesion increase crime and disorder, increasing fear, in turn, further decreasing cohesion. [source] Losartan decreases vasopressin-mediated cAMP accumulation in the thick ascending limb of the loop of Henle in rats with congestive heart failureACTA PHYSIOLOGICA, Issue 4 2007M. Torp Abstract Introduction:, Vasopressin (AVP) stimulates sodium reabsorption and Na,K,2Cl-cotransporter (NKCC2) protein level in the thick ascending limb (TAL) of Henle's loop in rats. Rats with congestive heart failure (CHF) have increased protein level of NKCC2, which can be normalized by angiotensin II receptor type-1 (AT1) blockade with losartan. Aim:, In this study, we investigated whether CHF rats displayed changes in AVP stimulated cAMP formation in the TAL and examined the role of AT1 receptor blockade on this system. Method:, CHF was induced by ligation of the left anterior descending coronary artery (LAD). SHAM-operated rats were used as controls. Half of the rats were treated with losartan (10 mg kg day,1 i.p.). Results:, CHF rats were characterized by increased left ventricular end diastolic pressure. Measurement of cAMP in isolated outer medullary TAL showed that both basal and AVP (10,6 m) stimulated cAMP levels were significantly increased in CHF rats (25.52 ± 4.49 pmol cAMP ,g,1 protein, P < 0.05) compared to Sham rats (8.13 ± 1.14 pmol cAMP ,g,1 protein), P < 0.05). Losartan significantly reduced the basal level of cAMP in CHF rats (CHF: 12.56 ± 1.93 fmol ,g,1 protein vs. Los-CHF: 7.49 ± 1.08, P < 0.05), but not in Sham rats (SHAM: 4.66 ± 0.59 vs. Los-SHAM: 4.75 ± 0.71). AVP-mediated cAMP accumulation was absent in both groups treated with losartan (Los-SHAM: 4.75 ± 0.71 and Los-CHF: 7.49 ± 1.08). Conclusion:, The results indicate that the increased NKCC2 protein level in the mTAL from CHF rats is associated with increased cAMP accumulation in this segment. Furthermore, the finding that AT1 receptor blockade prevents AVP-mediated cAMP accumulation in both SHAM and CHF rats suggests an interaction between angiotensin II and AVP in regulation of mTAL Na reabsorption. [source] Effects of transient muscle contractions and stretching on the tendon structures in vivoACTA PHYSIOLOGICA, Issue 2 2002K. KUBO ABSTRACT This study compared the effects of static stretching (ST) and repeated muscle contractions (CON) on the viscoelastic properties of tendon structures in vivo. Eight male subjects performed ST (passively flexed to 35 of dorsiflexion) for 5 min and 50 repetitions of isometric maximum voluntary contraction (MVC) for 3 s each with 3 s relaxation. Before and after each task, the elongation of the tendon and aponeurosis of the medial gastrocnemius muscle (MG) was directly measured by ultrasonography, while the subjects performed ramp isometric plantar flexion up to MVC, followed by a ramp relaxation. The relationship between the estimated muscle force (Fm) and tendon elongation (L) during the ascending phase was applied to a linear regression, the slope of which was defined as stiffness of the tendon structures. The percentage of the area within the Fm,L loop to the area beneath the curve during the ascending phase was calculated as an index representing hysteresis. The ST protocol significantly decreased the stiffness (,8%) and hysteresis (29%)., respectively. In contrast, the CON protocol significantly decreased the stiffness, but not the hysteresis. These results suggested that the stretching and repeated contractions would make the tendon structures more complaint, and further decreased the hysteresis of the tendon structures. [source] | ||||||||||||||||||||||||||||||||||||||||||||||||||||