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Performance Levels (performance + level)
Selected AbstractsA rapid screening LC-MS/MS method based on conventional HPLC pumps for the analysis of low molecular weight xenobiotics: application to doping control analysisDRUG TESTING AND ANALYSIS, Issue 7 2010Monica Mazzarino Abstract This study presents a fast multi-analyte screening method specifically developed for the detection of xenobiotics in urine. The proposed method allows the screening of several classes of substance in a single chromatographic method with a run-time of 11 min, inclusive of post-run and reconditioning times. Chromatographic separation is achieved in 7.2 min using a reversed-phase 2.7 µm fused-core particle column, generating a back-pressure not exceeding 400 bar and therefore enabling the use of traditional high performance liquid chromatography (HPLC) instruments. The effectiveness of this approach was evaluated, by liquid-chromatography tandem mass spectrometry (LC-MS/MS) in positive electrospray ionization, using 20 blank urine samples spiked with 45 compounds prohibited in sport: 11 diuretics, 16 glucocorticoids, 9 stimulants, 5 anti-oestrogens, as well as formoterol, carboxy-finasteride (previously prohibited by the World Anti-Doping Agency (WADA) in 2008), gestrinone and tetrahydrogestrinone. Qualitative validation shows the proposed method to be specific with no significant interference. All of the analytes considered in this study were clearly distinguishable in urine, with limits of detection ranging from 5 ng/mL to 350 ng/mL, significantly below the Minimum Required Performance Levels (MRPL) set by WADA for the accredited sports anti-doping laboratories. All compounds of interest were separated, including synthetic and endogenous glucocorticoids with similar retention times and fragmentation patterns. Copyright © 2010 John Wiley & Sons, Ltd. [source] Psychometric Properties of Scale Scores and Performance Levels for Performance Assessments Using Polytomous IRTJOURNAL OF EDUCATIONAL MEASUREMENT, Issue 2 2000Tianyou Wang With a focus on performance assessments, this paper describes procedures for calculating conditional standard error of measurement (CSEM) and reliability of scale scores and classification consistency of performance levels. Scale scores that are transformations of total raw scores are the focus of these procedures, although other types of raw scores are considered as well. Polytomous IRT models provide the psychometric foundation for the procedures that are described. The procedures are applied using test data from ACT's Work Keys Writing Assessment to demonstrate their usefulness. Two polytomous IRT models were compared, as were two different procedures for calculating scores. One simulation study was done using one of the models to evaluate the accuracy of the proposed procedures. The results suggest that the procedures provide quite stable estimates and have the potential to be useful in a variety of performance assessment situations. [source] Accuracy and Fluency in List and Context Reading of Skilled and RD Groups: Absolute and Relative Performance LevelsLEARNING DISABILITIES RESEARCH & PRACTICE, Issue 4 2003Joseph R. Jenkins The purpose of this study was to examine (1) the performance levels and the magnitude of performance difference between students with reading disabilities (RD) and skilled readers when reading a typical classroom text; (2) the hypothesis that students with RD have specific difficulty using context in such a way that reading fluency is affected; and (3) whether RD subtypes may be differentiated according to performance on contextual and context-free reading tasks. Two groups of fourth graders (85 skilled readers and 24 students with RD) completed a standardized test of reading comprehension, read aloud a folktale, and read aloud the folktale's words in a randomly sequenced list. Performance was scored as correct rate and percentage correct. Based on the number of words per idea unit in the passage, we also estimated the rate at which reader groups encountered and processed text ideas. Compared to the RD group, skilled readers read three times more correct words per minute in context, and showed higher accuracy and rates on all measures. Both context and isolated word-reading rates were highly sensitive to impairment. We found no evidence for RD subtypes based on these measures. Results illustrate differences in reading levels between the two groups, the temporal advantage skilled readers have in linking text ideas, how word reading differs as a function of task format and performance dimension, and how limited word-identification skills (not comprehension) produce contextual reading difficulties for students with RD. [source] Probabilistic Approach for Nonlinear Modal Control of MDOF Structures Subjected to Multiple ExcitationsCOMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 1 2005Kyung-Won Min For the modal control of the MDOF structure, a new eigenvalue assignment algorithm that modifies the dynamic characteristics of only the specific mode is proposed. For the probabilistic evaluation of the proposed nonlinear modal control, the joint probability density function (PDF) of the equivalent nonlinearly controlled single-degree-of-freedom (SDOF) system is obtained by the solution of the reduced Fokker,Planck equation for the equivalent nonlinear system. To overcome the difficulty in the application of the joint PDF to the MDOF structure controlled by the hybrid mass damper (HMD) system and subjected to multiple excitations, the equivalent damping ratio is proposed. The results of the analysis indicate that the proposed nonlinear modal control strategy is effective for the control of MDOF structures requiring a significantly smaller peak control force than the linear quadratic Gaussian (LQG) controller to produce a similar control performance level. [source] Improved design of sliding mode control for civil structures with saturation problemEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 11 2004Sang-Hyun Lee Abstract A systematic and improved design procedure for sliding mode control (SMC) of seismically excited civil structures with saturation problem is provided in this paper. In order to restrict the control force to a certain level, a procedure for determining the upper limits of the control forces for single or multiple control units is proposed based on the design response spectrum of external loads. Further, an efficient procedure using the LQR method for determining sliding surfaces appropriate for different controller types is provided through the parametric evaluation of the dynamic characteristics of sliding surfaces in terms of SMC controller performance. Finally, a systematic design procedure for SMC required to achieve a given performance level is provided and its effectiveness is verified by applying it to multi-degree-of-freedom (MDOF) systems. Copyright © 2004 John Wiley & Sons, Ltd. [source] An investigation of the relationship between race performance and superficial digital flexor tendonitis in the Thoroughbred racehorseEQUINE VETERINARY JOURNAL, Issue 4 2010B. O'MEARA Summary Reasons for performing study: There is limited information regarding the number of races and the period for evaluation of outcome which is critical for assessment of SDF tendonitis treatments. Objective: To evaluate the re-injury rate and racing performance of Thoroughbred racehorses that sustain SDF tendonitis in relation to matched controls in terms of number of races post treatment and maximum racing performance ratings before and after injury. Study design: Clinical records and racing histories of 401 racehorses with a first occurrence of SDF tendonitis diagnosed by ultrasonography. Controls were of the same age, sex and were horses training in the same establishment at the time of injury as the case horses and where the trainer reported that the horse had not had a previous SDF tendon injury or treatment. Results: Eighty percent of both case and control horses returned to racing after the date of injury, and the re-injury proportion within 3 years of treatment was 53%. The difference in Racing Post Rating(max) (RPR(max)) and the Racing Post Rating in the race immediately before the treatment date was significantly smaller in case horses (mean = 9.6 lbs; range = 0,75) compared to control horses (mean = 17.0 lbs; range = 0,79). No significant decrease in RPR(max) was noted post injury. No difference between case and control horses was found for return to racing and racing 3 times, but control horses were significantly more likely to compete 5 races post treatment date than case horses. Conclusion and clinical relevance: Injury was associated with an individual's pre-injury maximum performance level and return to racing and completion of 3 races are not useful indicator of the outcome of horses with SDF tendonitis. The assessment of the outcome of horses with an SDF injury in a population of racehorses using the number of races post injury requires a minimum of 5 races post injury to be a useful indicator. Further, a re-injury proportion in a population of horses in training for 3 years post treatment. [source] Osseous abnormalities associated with collateral desmopathy of the distal interphalangeal joint.EQUINE VETERINARY JOURNAL, Issue 8 2009Part 2: Treatment, outcome Summary Reasons for performing study: There are currently few long-term follow-up data relating to recovery from injury of a collateral ligament (CL) of the distal interphalangeal (DIP) joint and limited information about the effect of associated osseous injury on prognosis. Objectives: To describe long-term follow-up results for horses with CL injury, with and without associated osseous injury; and to determine the effect of extracorporeal shock wave therapy (ECSWT) or radial pressure wave therapy (RPWT) on outcome. Hypotheses: Prognosis for return to performance for horses with CL-related osseous injury would be worse than for horses with CL injury alone. Methods: Magnetic resonance images from 313 feet of 289 horses with foot pain and a definitive diagnosis of collateral desmopathy of the DIP joint were analysed retrospectively for presence of osseous abnormality associated with the ligament origin or insertion and the middle and distal phalanges. Horses were assigned to groups according to the combination of their injuries. Type of treatment was recorded and follow-up information obtained. Thirty-two horses with additional sources of lameness were excluded from analysis of outcome. Results: Follow-up data were available for 182 horses, 55 of which had follow-up information for up to 2 years after presentation. Twenty-seven percent of horses with CL injury alone and 34% of horses with CL related osseous injury returned to their previous performance level. Prognosis for a combination of injuries to multiple soft tissue and osseous structures within the hoof capsule was substantially worse. There was no effect of ECSWT or RPWT on outcome. Conclusions: The presence of mild to moderate CL related osseous injury does not appear to influence prognosis compared with CL injury alone. Clinical relevance: Further studies of a larger number of horses are necessary in order to ascertain if specific types of osseous pathology influence return to performance levels. [source] Association of type of sport and performance level with anatomical site of orthopaedic injury diagnosisEQUINE VETERINARY JOURNAL, Issue S36 2006R. C. MURRAY Summary Reason for performing study: Although anecdotal reports of increased orthopaedic injury risk in equine sports exist, there is little scientific evidence to support this. Objectives: To test whether horses undertaking a single competitive sport have increased risk of specific injuries compared to those used for general purpose riding (GP); and whether injury type varies with sport category and performance level. Methods: Data from 1069 records of horses undergoing orthopaedic evaluation (1998,2003) and meeting inclusion criteria were reviewed. Sport category (GP, showjumping, dressage, eventing, racing), level (nonelite or elite) and diagnosis were recorded. Effects of sport category and level on probability of a specific diagnosis were assessed using chisquared tests. Logistic regression was used to determine which competitive sports and levels increased risk of injury compared with GP. Results: Overall there was a significant effect of sport category and level on diagnosis (P<0.0001). There was significant difference between anatomical site injured and sport category (P<0.0001); a high risk of forelimb superficial digital flexor tendon injury in elite eventing (P<0.0001) and elite showjumping (P=0.02); distal deep digital flexor tendon (DDFT) injury in elite showjumping (P=0.002); and hindlimb suspensory ligament injury in elite (P<0.0001) and nonelite (P=0.001) dressage. There was a low risk of tarsal injury in elite eventing (P=0.01) and proximal DDFT injury in dressage (P = 0.01). Conclusions: Horses competing in different sports are predisposed to specific injuries; particular sports may increase the risk of injury at certain anatomical sites; and the type and site of injury may reflect the type and level of performance. Potential relevance: These findings could guide clinicians in the diagnosis of sport related injuries. [source] Novel Polymer Electrolyte Membranes for Automotive Applications , Requirements and Benefits,FUEL CELLS, Issue 4 2004C. Wieser Abstract During the past few years, the feasibility of using polymer electrolyte fuel cells in automotive power trains at an impressive performance level has been proven repeatedly. However, current fuel cell stacks are still largely based on decade-old polymer electrolyte membrane technology thus limiting performance, durability, reliability, and cost of the fuel cell systems. The major challenge for membrane R&D constitutes the demand for polymer electrolytes that allow for system operation at higher temperatures and lower water management requirements without increased conduction losses. None the less, demanding automotive requirements will not compromise on other properties such as mechanical and chemical stability and gas permeability. [source] Performance of delay-sensitive traffic in multi-layered satellite IP networks with on-board processing capabilityINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 12 2007Suzan Bayhan Abstract In this article, performance of delay-sensitive traffic in multi-layered satellite Internet Protocol (IP) networks with on-board processing (OBP) capability is investigated. With OBP, a satellite can process the received data, and according to the nature of application, it can decide on the transmission properties. First, we present a concise overview of relevant aspects of satellite networks to delay-sensitive traffic and routing. Then, in order to improve the system performance for delay-sensitive traffic, specifically Voice over Internet Protocol (VoIP), a novel adaptive routing mechanism in two-layered satellite network considering the network's real-time information is introduced and evaluated. Adaptive Routing Protocol for Quality of Service (ARPQ) utilizes OBP and avoids congestion by distributing traffic load between medium-Earth orbit and low-Earth orbit layers. We utilize a prioritized queueing policy to satisfy quality-of-service (QoS) requirements of delay-sensitive applications while evading non-real-time traffic suffer low performance level. The simulation results verify that multi-layered satellite networks with OBP capabilities and QoS mechanisms are essential for feasibility of packet-based high-quality delay-sensitive services which are expected to be the vital components of next-generation communications networks. Copyright © 2007 John Wiley & Sons, Ltd. [source] Observer design with guaranteed RMS gain for discrete-time LPV systems with Markovian jumpsINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 6 2009Giuseppe C. Calafiore Abstract In this paper we consider the problem of designing state observers with guaranteed power-to-power (RMS) gain for a class of stochastic discrete-time linear systems that possess both measurable parameter variations and Markovian jumps in their dynamics. It is shown in the paper that an upper bound on the RMS gain of the observer can be characterized in terms of feasibility of a family of parameter-dependent linear matrix inequalities (LMIs). Any feasible solution to these LMIs can then be used to explicitly construct a parameter-varying jump observer that guarantees the desired performance level. This design framework is then specialized to a problem of state estimation for a linear parameter-varying plant whose state measurements are available through a lossy Bernoulli channel. Two numerical examples illustrate the results. Copyright © 2008 John Wiley & Sons, Ltd. [source] Design of distributed controllers with constrained and noisy linksINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 18 2006Shengxiang Jiang Abstract In this paper we consider some design aspects of distributed controllers that guarantee a ,, performance level. In particular, we consider two design problems. First, is the case where, without loss of generality, there are two distributed subcontrollers connected to a (generalized) plant and the interest is placed in minimizing the number of noise-free (and dynamics free) communication channels between the subcontrollers needed to provide a given performance. The second is the case where, given a distributed controller designed in the first case, communication noise is present and we seek an optimal choice of the communication signals to guarantee a performance level while keeping the communication signal to noise power limited. We take a linear matrix inequality (LMI) approach to provide solution procedures to these problems and present examples that demonstrate their efficiency. Copyright © 2006 John Wiley & Sons, Ltd. [source] Delay-dependent fault estimation for uncertain time-delay nonlinear systems: an LMI approachINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 18 2006Sing Kiong Nguang Abstract This paper deals with the problem of robust fault estimation for uncertain time-delay Takagi,Sugeno (TS) fuzzy models. The aim of this study is to design a delay-dependent fault estimator ensuring a prescribed ,, performance level for the fault estimation error, irrespective of the uncertainties and the time delays. Sufficient conditions for the existence of a robust fault estimator are given in terms of linear matrix inequalities (LMIs). Membership functions' (MFs) characteristics are incorporated into the fault estimator design to reduce the conservativeness of neglecting these characteristics. Finally, a numerical example is given to illustrate the effectiveness of the proposed design techniques. Copyright © 2006 John Wiley & Sons, Ltd. [source] The Impact of Performance Level Misclassification on the Accuracy and Precision of Percent at Performance Level MeasuresJOURNAL OF EDUCATIONAL MEASUREMENT, Issue 2 2008Damian W. Betebenner No Child Left Behind (NCLB) performance mandates, embedded within state accountability systems, focus school AYP (adequate yearly progress) compliance squarely on the percentage of students at or above proficient. The singular importance of this quantity for decision-making purposes has initiated extensive research into percent proficient as a measure of school quality. In particular, technical discussions have scrutinized the impact of sampling, measurement, and other sources of error on percent proficient statistics. In this article, we challenge the received orthodoxy that measurement error associated with individual students' scores is inconsequential for aggregate percent proficient statistics. Synthesizing current classification accuracy research with techniques from randomized response designs, we establish results which specify the extent to which measurement error,manifest as performance level misclassifications,produces bias and increases error variability for percent at performance level statistics. The results have direct relevance for the design of coherent and fair accountability systems based upon assessment outcomes. [source] Loss characteristics of coplanar waveguide transmission lines fabricated with copper nanoparticlesMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 3 2010Hee-Jo Lee Abstract This article investigates the high frequency characteristics of coplanar waveguide (CPW) lines fabricated with inkjet-printing technology on BT substrates. The optimal metallic thickness of a printed CPW line is approximately estimated to be 3 ,m. When printed lines with higher electrical conductivity are realized through additional surface preparation steps, the findings of this study suggest that the RF performance level of these printed lines will be comparable to that of the copper clad laminate lines in the microwave frequency region. Finally, aspects of such improvements as well as applications of these types of printed lines are discussed. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 780,782, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24987 [source] HOW TO RECTIFY UNFAIR TRADE PRACTICES AND TO ESTABLISH APPROPRIATE SUPPLY CHAINS AND BETTER BUSINESS CULTURE UNDER THE GLOBAL MARKET ECONOMYPACIFIC ECONOMIC REVIEW, Issue 5 2009Tsugio Ide Banning unfair trade practices stands alongside private monopolization and the unjust restraint of trade as a key theme in competition policy. However, it poses much greater difficulties to deal with the matter than either private monopolization or unjust restraint of trade. In recent years, ongoing economic globalization, advances in information communication technology and other factors have wrought major changes in the traditional supply chain: for example, in subcontracting structure. Given the role of small and medium enterprises in underpinning economic growth, lifting the basic quality and performance level of these firms and improving business conditions for them have emerged as key policy themes. New efforts are needed to establish fair trade as a business practice and to create a new business culture in corporation with competition policy, small and medium enterprise policy and business ethics, such as Corporate Social Responsibility (CSR) practices. [source] Comparison of hangover effects among triazolam, flunitrazepam and quazepam in healthy subjects: A preliminary reportPSYCHIATRY AND CLINICAL NEUROSCIENCES, Issue 3 2003Taro Takahashi Abstract The aim of the present study was to compare the hangover effects of night-time administration of triazolam (0.25 mg), flunitrazepam (1 mg) and quazepam (15 mg) in healthy subjects. Daytime sleepiness and performance level following the night-time administration of the drugs were assessed using Standford Sleepiness Scale (SSS), Sleep Evaluation Questionnaire (SEQ), Multiple Sleep Latency Test (MSLT), actigraphy recordings and Continuous Performance Test (CPT). Fifteen healthy volunteers were given one of the three hypnotics at each drug session, which lasted for 1 week, in a single-blind cross-over fashion. No significant between-drug difference was observed for the psychomotor performance assessed by CPT. Subjective hangover effects assessed by SSS and SEQ in the morning were prominent for flunitrazepam and quazepam relative to triazolam, whereas objective indices such as MSLT or activity counts obtained in actigraphy indicated a marked hangover effect of quazepam compared with the other two compounds restrictively in the afternoon, which were nearly in accordance with their pharmacokinetic profiles. [source] Design of robust non-fragile H, filters for uncertain neutral stochastic systems with distributed delays,ASIAN JOURNAL OF CONTROL, Issue 1 2010Bo Song Abstract This paper deals with the problem of robust non-fragile H, filtering for neutral stochastic systems with distributed delays and norm-bounded parameter uncertainties. Attention is focused on the design of a filter which is subject to gain variations, such that the filtering error system is robustly stochastically stable with a prescribed H, performance level for all admissible uncertainties. A delay-dependent sufficient condition for the solvability of this problem is obtained in terms of a linear matrix inequality. Copyright © 2009 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society [source] NETWORK-INDUCED DELAY-DEPENDENT H, CONTROLLER DESIGN FOR A CLASS OF NETWORKED CONTROL SYSTEMSASIAN JOURNAL OF CONTROL, Issue 2 2006Xiefu Jiang ABSTRACT This paper is concerned with the problem of robust H, controller design for a class of uncertain networked control systems (NCSs). The network-induced delay is of an interval-like time-varying type integer, which means that both lower and upper bounds for such a kind of delay are available. The parameter uncertainties are assumed to be normbounded and possibly time-varying. Based on Lyapunov-Krasovskii functional approach, a robust H, controller for uncertain NCSs is designed by using a sum inequality which is first introduced and plays an important role in deriving the controller. A delay-dependent condition for the existence of a state feedback controller, which ensures internal asymptotic stability and a prescribed H, performance level of the closed-loop system for all admissible uncertainties, is proposed in terms of a nonlinear matrix inequality which can be solved by a linearization algorithm, and no parameters need to be adjusted. A numerical example about a balancing problem of an inverted pendulum on a cart is given to show the effectiveness of the proposed design method. [source] Debriefing as Formative Assessment: Closing Performance Gaps in Medical EducationACADEMIC EMERGENCY MEDICINE, Issue 11 2008Jenny W. Rudolph PhD Abstract The authors present a four-step model of debriefing as formative assessment that blends evidence and theory from education research, the social and cognitive sciences, experience drawn from conducting over 3,000 debriefings, and teaching debriefing to approximately 1,000 clinicians worldwide. The steps are to: 1) note salient performance gaps related to predetermined objectives, 2) provide feedback describing the gap, 3) investigate the basis for the gap by exploring the frames and emotions contributing to the current performance level, and 4) help close the performance gap through discussion or targeted instruction about principles and skills relevant to performance. The authors propose that the model, designed for postsimulation debriefings, can also be applied to bedside teaching in the emergency department (ED) and other clinical settings. [source] Memory function in normal agingACTA NEUROLOGICA SCANDINAVICA, Issue 2003Lars-Göran Nilsson Basic findings obtained on memory functions in normal aging are presented and discussed with respect to five separate but interacting memory systems. These systems are: episodic memory, semantic memory, short-term memory, perceptual representation system and procedural memory. All available evidence from cross-sectional research shows that there is a linear, decreasing memory performance as a function of age for episodic memory. Longitudinal studies suggest, however, that this age deficit may be an overestimation, by showing a relatively stable performance level up to middle age, followed by a sharp decline. Studies on semantic memory, short-term memory, perceptual representation system, and procedural memory show a relatively constant performance level across the adult life span, although some tasks used to assess short-term memory and procedural memory have revealed an age deficit. Disregarding the mixed results for these latter two memory systems, it can be concluded that episodic memory is unique in showing an age deficit. Episodic memory is also unique in the sense that it is the only memory system showing gender differences in performance throughout the adult life span with a significantly higher performance for women. [source] Uniform hazard versus uniform risk bases for performance-based earthquake engineering of light-frame wood constructionEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 11 2010Yue Li Abstract This paper investigates the implications of designing for uniform hazard versus uniform risk for light-frame wood residential construction subjected to earthquakes in the United States. Using simple structural models of one-story residences with typical lateral force-resisting systems (shear walls) found in buildings in western, eastern and central regions of the United States as illustrations, the seismic demands are determined using nonlinear dynamic time-history analyses, whereas the collapse capacities are determined using incremental dynamic analyses. The probabilities of collapse, conditioned on the occurrence of the maximum considered earthquakes and design earthquakes stipulated in ASCE Standard 7-05, and the collapse margins of these typical residential structures are compared for typical construction practices in different regions in the United States. The calculated collapse inter-story drifts are compared with the limits stipulated in FEMA 356/ASCE Standard 41-06 and observed in the recent experimental testing. The results of this study provide insights into residential building risk assessment and the relation between building seismic performance implied by the current earthquake-resistant design and construction practices and performance levels in performance-based engineering of light-frame wood construction being considered by the SEI/ASCE committee on reliability-based design of wood structures. Further code developments are necessary to achieve the goal of uniform risk in earthquake-resistant residential construction. Copyright © 2010 John Wiley & Sons, Ltd. [source] Simplified inelastic seismic analysis of base-isolated structures using the N2 methodEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 9 2010Vojko Kilar Abstract In the paper a simplified nonlinear method has been applied to the analysis of base-isolated structures. In the first part, a three-linear idealization of the capacity curve is proposed. The initial stiffness is defined based on the first yielding point in the superstructure, whereas the secondary slope depends on the failure mechanism of the superstructure. A consequence is a much more pronounced secondary slope, which does not correspond to the presumptions used in the originally proposed N2 method. A parametric nonlinear dynamic study of single degree of freedom systems with different hardening slopes and damping has been performed for an ensemble of seven EC8 spectrum-compatible artificial accelerograms. It was concluded that, in the long-period range, the equal displacement rule could be assumed also for the proposed systems with non-zero post-yield stiffness. In the second part, the proposed idealization was used for the analysis of isolated RC frame buildings that were isolated with different (lead) rubber-bearing isolation systems. The stiffness of the isolators was selected for three different protection levels and for three different ground motion intensities, which have resulted in elastic as well as moderately and fully damaged superstructure performance levels. Three different lateral load distributions were investigated. It was observed that a triangular distribution, with an additional force at the base, works best in the majority of practical cases. It was concluded that the N2 method can, in general, provide a reasonably accurate prediction of the actual top displacement, as well as of the expected damage to the superstructure. Copyright © 2009 John Wiley & Sons, Ltd. [source] Strengthening of moment-resisting frame structures against near-fault ground motion effectsEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 6 2004Babak Alavi Abstract Near-fault ground motions with forward directivity are characterized by a large pulse. This pulse-like motion may cause a highly non-uniform distribution of story ductility demands for code-compliant frame structures, with maximum demands that may considerably exceed the level of code expectations. Strengthening techniques for multi-story frame structures are explored with the objective of reducing maximum drift demands. One option is to modify the code-based SRSS distribution of story shear strength over the height by strengthening of the lower stories of the frame. The modified distribution reduces the maximum story ductility demand, particularly for weak and flexible structures. However, this strengthening technique is less effective for stiff structures, and is almost ineffective in cases in which the maximum demand occurs in the upper stories, i.e. strong and flexible structures. As an alternative, the benefits of strengthening frames with elastic and inelastic walls are evaluated. The effects of adding walls that are either fixed or hinged at the base are investigated. It is demonstrated that strengthening with hinged walls is very effective in reducing drift demands for structures with a wide range of periods and at various performance levels. Wall inelastic behavior only slightly reduces the benefits of strengthening with hinged walls.Copyright © 2004 John Wiley & Sons, Ltd. [source] Osseous abnormalities associated with collateral desmopathy of the distal interphalangeal joint.EQUINE VETERINARY JOURNAL, Issue 8 2009Part 2: Treatment, outcome Summary Reasons for performing study: There are currently few long-term follow-up data relating to recovery from injury of a collateral ligament (CL) of the distal interphalangeal (DIP) joint and limited information about the effect of associated osseous injury on prognosis. Objectives: To describe long-term follow-up results for horses with CL injury, with and without associated osseous injury; and to determine the effect of extracorporeal shock wave therapy (ECSWT) or radial pressure wave therapy (RPWT) on outcome. Hypotheses: Prognosis for return to performance for horses with CL-related osseous injury would be worse than for horses with CL injury alone. Methods: Magnetic resonance images from 313 feet of 289 horses with foot pain and a definitive diagnosis of collateral desmopathy of the DIP joint were analysed retrospectively for presence of osseous abnormality associated with the ligament origin or insertion and the middle and distal phalanges. Horses were assigned to groups according to the combination of their injuries. Type of treatment was recorded and follow-up information obtained. Thirty-two horses with additional sources of lameness were excluded from analysis of outcome. Results: Follow-up data were available for 182 horses, 55 of which had follow-up information for up to 2 years after presentation. Twenty-seven percent of horses with CL injury alone and 34% of horses with CL related osseous injury returned to their previous performance level. Prognosis for a combination of injuries to multiple soft tissue and osseous structures within the hoof capsule was substantially worse. There was no effect of ECSWT or RPWT on outcome. Conclusions: The presence of mild to moderate CL related osseous injury does not appear to influence prognosis compared with CL injury alone. Clinical relevance: Further studies of a larger number of horses are necessary in order to ascertain if specific types of osseous pathology influence return to performance levels. [source] Foraging for Work and Age-Based Polyethism: The Roles of Age and Previous Experience on Task Choice in AntsETHOLOGY, Issue 11 2004Frederic Tripet In social insects, colonies commonly show temporal polyethism in worker behavior, such that a worker follows a predictable pattern of changes between tasks as it ages. This pattern usually leads from workers first doing a safe task like brood care, to ending their lives doing the most dangerous tasks like foraging. Two mechanisms could potentially underlie this pattern: (1) age-based task allocation, where the aging process itself predisposes workers to switch to more dangerous tasks; and (2) foraging for work, where ants switch to tasks that need doing from tasks which have too many associated workers. We tested the relative influence of these mechanisms by establishing nests of Camponotus floridanus with predetermined combinations of workers of known age and previous task specialization. The results supported both mechanisms. Nests composed of entirely brood-tending workers had the oldest workers preferentially switching to foraging. However, in nests initially composed entirely of foragers, the final distribution of tenders and foragers was not different from random task-switching and therefore supportive of foraging for work. Thus, it appears that in C. floridanus there is directionality to the mechanisms of task allocation. Switching to more dangerous tasks is age-influenced, but switching to less dangerous tasks is age-independent. The results also suggest that older workers are more flexible in their task choice behavior. Younger workers are more biased towards choosing within-nest tasks. Finally, there are effects of previous experience that tend to keep ants in familiar tasks. Task allocation based on several mechanisms may balance between: (1) concentrating the most worn workers into the most dangerous tasks; (2) increasing task performance levels; and (3) maintaining behavioral flexibility to respond to demographic perturbations. The degree to which behavior is flexible may correlate to the frequency of such perturbations in a species. [source] Performance of the Dual-Banyan ATM switch under arbitrary traffic patterns,EUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 4 2003Igor Radusinovic Dual-Banyan (DB) is a buffered banyan asynchronous transfer mode (ATM) switch encompassing multiple input-queueing (bifurcated queueing) as its buffering strategy. This paper describes a new analytical model for a performance evaluation of the DB switch under arbitrary traffic patterns. The model developed and presented enables the computation of the switch normalized throughput and the average packet delay by iterative calculations. The efficiency of the given model is verified through a comparison with simulation results, too. We compare throughputs of DB switch and input buffer banyan, and show that DB switch has significantly better performance levels. Copyright © 2003 AEI. [source] Brain Electrical Activity Associated With Cognitive Processing During a Looking Version of the A-Not-B TaskINFANCY, Issue 3 2001Martha Ann Bell This work was designed to investigate individual differences in brain electrical activity during a looking version of the A-not-B task. It was proposed that this spatial task required the cognitive skills of working memory and inhibitory control, each associated with frontal lobe function. Electroencephalograms (EEGs) were recorded from 54 8-month-old infants during baseline and task. Only high performers on the looking task exhibited increases in 6- to 9-Hz EEG power from baseline to task. These task-related changes were evident at frontal and posterior scalp locations. High performers on the looking task exhibited lower EEG coherence values at right hemisphere frontal locations relative to the low performers. These lower coherence values were evident during baseline and task. All infants showed increased frontal-parietal coherence during the spatial working memory task relative to baseline values. These data confirm previous cognitive neuroscience work associating frontal lobe function with cognitive performance levels during infancy. [source] EQAS for peripheral blood morphology in Spain: a 6-year experienceINTERNATIONAL JOURNAL OF LABORATORY HEMATOLOGY, Issue 6 2008G. GUTIÉRREZ Summary The Spanish haematology external quality assessment scheme (EQAS), established in 1984, is run by the Spanish Haematology and Haemotherapy Association (AEHH) [Quality Assurance in Health Care 3 (1991) 75] and functions to evaluate the quality and reproducibility of the assessment of diagnostic samples by clinical laboratories. The Hospital Clinic of the University of Barcelona (HCB) serves as the EQAS Coordination Centre and follows the guidelines established by the International Committee for Standardization in Haematology [Annali dell'Istituto superiore di Sanitŕ 31 (1995) 95; International Journal of Hematology 68 (1998) 45]. During the period 2001,2006, replicates of 25 different blood films were sent to 604 EQAS participants for cell morphology evaluation. Some patient details corresponding to the samples were disclosed, such us age, sex, haemoglobin value and white blood cell count. The participants were asked to select up to four significant morphology features using a coding list, provided by the Coordination Centre, which included significant morphological alterations that appear in haematopoietic cells. For each survey, individual results were assessed against the morphological reference results (MRR) established by the Cytology Group of the AEHH (,true' answers). This paper describes the organization of the 6-year-long study and the evaluation of laboratory performance for blood smear interpretation by the Spanish haematology EQAS. Different performance levels were detected relative to the laboratory category. Laboratories providing services to hospitalized patients showed higher performances compared with laboratories providing services to nonhospitalized patients. Pathological lymphoid cells were the most difficult to identify by the participants. To improve the results in EQAS peripheral blood morphology, the development of specific cytology educational trainings is discussed. [source] Red-winged blackbirds Ageliaus phoeniceus respond differently to song types with different performance levelsJOURNAL OF AVIAN BIOLOGY, Issue 1 2007Emily R. A. Cramer Physical constraints on animal signals can have important consequences for communication. For bird songs that include a trill, performance is physically constrained by a trade-off between the rate at which notes are repeated in the trill and the sound frequency range covered, such that a trill cannot exceed a certain frequency range for a given note repetition rate. Producing trills that are closer to this performance limit is presumably more challenging for birds than producing trills that are farther from it. Male red-winged blackbirds Ageliaus phoeniceus have repertoires of two to eight song types containing trills that span a range of performance levels. We determined the approximate trill performance maximum for a population of red-winged blackbirds, then conducted playback experiments to measure the responses of territorial males to song types with either high or low performance levels relative to this limit. Males responded significantly more strongly to songs containing low performance trills. Our results show that male red-winged blackbirds can discriminate between different song performance levels, suggesting that vocal proficiency plays a role in male-male interactions. [source] | ||||||||||||||||||||||||||||