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Agents
Kinds of Agents Terms modified by Agents Selected AbstractsTHE U.S. MILITARY AS GEOGRAPHICAL AGENT: THE CASE OF COLD WAR ALASKA,GEOGRAPHICAL REVIEW, Issue 1 2005LAUREL J. HUMMEL ABSTRACT. Alaska was strategically key to the U.S. defense plan during the cold war (1946,1989). As such, it was the scene of an enormous and sustained military investment, the effect of which was amplified by Alaska's undiversified economy, sparse development, small resident population, and marginalized political status at the beginning of the era. The strong military presence affected Alaskan demographics, economic development, and infrastructure and figured prominently in the admission of Alaska to the union in 1959. The high profile and long-term presence of the U.S. military had such a dramatic affect on the course of Alaska that the result was tantamount to a "militarized landscape." [source] EFFECTS OF A 10% CARBAMIDE PEROXIDE BLEACHING AGENT ON ROUGHNESS AND MICROHARDNESS OF PACKABLE COMPOSITE RESINSJOURNAL OF ESTHETIC AND RESTORATIVE DENTISTRY, Issue 4 2005Jeffrey Y. Thompson PhD [source] THE IMPACT OF RENT CONTROLS IN NON-WALRASIAN MARKETS: AN AGENT-BASED MODELING APPROACHJOURNAL OF REGIONAL SCIENCE, Issue 3 2006Ralph Bradburd ABSTRACT We use agent-based models to consider rent ceilings in non-Walrasian housing markets, where bargaining between landlord and tenant leads to exchange at a range of prices. In the non-Walrasian setting agents who would be extramarginal in the Walrasian setting frequently are successful in renting, and actually account for a significant share of the units rented. This has several implications. First, rent ceilings above the Walrasian equilibrium price (WEP) can affect the market outcome. Second, rent ceilings that reduce the number of units rented do not necessarily reduce total market surplus. Finally, the distributional impact of rent controls differs from the Walrasian setting. [source] A NEW HAEMODIALYSIS CATHETER-LOCKING AGENT REDUCES INFECTIONS IN HAEMODIALYSIS PATIENTSJOURNAL OF RENAL CARE, Issue 3 2008Caroline Taylor SUMMARY Background: Intravenous catheters for haemodialysis increase the risk of sepsis. This study investigates the use of a taurolidine/citrate catheter-locking agent for patients receiving hospital-based haemodialysis, auditing the number and cost of infections before and after its introduction. Methods: The incidence and cost of treatment of catheter sepsis occurring in all patients receiving haemodialysis via a line were investigated over 6-month periods before and after introducing the taurolidine/citrate line-locking agent. Results: A reduction of 4.62 infections per 1000 catheter days, or 88.5%, was shown after the introduction of the new line-locking agent. The total costs of line infections in the first 6 months were ,52 500, (£41 000); after the introduction of the taurolidine/citrate locks, these reduced to ,33 300, (£26 000), a reduction of ,19 200 (£15 000). Conclusions: The use of a taurolidine/citrate haemodialysis catheter-locking agent in our haemodialysis population has significantly reduced the line sepsis rate, with a positive impact on morbidity, mortality and cost. [source] THE USE OF TOMATO PULP POWDER AS A THICKENING AGENT IN THE FORMULATION OF TOMATO KETCHUPJOURNAL OF TEXTURE STUDIES, Issue 2 2008A. FARAHNAKY ABSTRACT In this current study, tomato pulp powder, the main waste of the tomato processing industry, was used as a thickening agent in the formulation of a commercial tomato ketchup at different levels (1, 2, 5, 7 and 10% w/w). Color parameters (L and a/b) and rheologic properties of the formulated ketchups with and without added tomato pulp powder were determined and compared. The addition of the pulp powder caused a significant increase in the L value of the samples, while a/b ratio decreased notably. The rheologic data obtained were fitted using a power law equation. The analysis of the data obtained revealed that low levels of tomato pulp powder can compete with other hydrocolloids in improving the consistency of tomato ketchup. All ketchup samples in this study were non-Newtonian fluids and the apparent viscosity of the ketchups increased significantly with increasing concentration of tomato pulp powder and decreased with temperature increase. Chemical composition (protein, total fat, reducing and total sugars, fiber, ascorbic acid and ash contents) and some physicochemical properties of the tomato pulp powder, including water absorption and solubility, were determined and the data were used for the interpretation of the rheologic and color changes as a result of the inclusion of the pulp powder in the formulation. PRACTICAL APPLICATIONS The direct use of food industry wastes in food formulations can help in reducing the production costs by decreasing raw material and disposal costs. The classic design of the tomato processing plants results in generating a large amount of tomato pulp. The results of this research confirmed that tomato pulp powder can be used instead of other hydrocolloids in tomato-based products. The reuse of tomato pulp powder in foods can be beneficial to producers and the environment. [source] ,YOU MIGHT AS WELL BE HUNG FOR A SHEEP AS A LAMB': THE LOSS FUNCTION OF AN AGENT,THE MANCHESTER SCHOOL, Issue 3 2008MARGARET BRAY Most of those who take macro and monetary policy decisions are agents. The worst penalty which can be applied to these agents is to sack them. Agents thus have loss functions which are bounded above. We work with a bell loss function which has this property. With additive uncertainty the certainty equivalence which holds for a quadratic loss function breaks down with a bell loss function when there are two or more targets. With multiplicative (Brainard) uncertainty policy is more conservative than in the absence of multiplicative uncertainty, but less so with the bell than the quadratic loss function. [source] COALITIONS AMONG INTELLIGENT AGENTS: A TRACTABLE CASECOMPUTATIONAL INTELLIGENCE, Issue 1 2006M. V. Belmonte Coalition formation is an important mechanism for cooperation in multiagent systems. In this paper we address the problem of coalition formation among self-interested agents in superadditive task-oriented domains. We assume that each agent has some "structure," i.e., that it can be described by the values taken by a set of m nonnegative attributes that represent the resources w each agent is endowed with. By defining the coalitional value as a function V of w, we prove a sufficient condition for the existence of a stable payment configuration,in the sense of the core,in terms of certain properties of V. We apply these ideas to a simple case that can be described by a linear program and show that it is possible to compute for it,in polynomial time,an optimal task allocation and a stable payment configuration. [source] FAST AND ROBUST INCREMENTAL ACTION PREDICTION FOR INTERACTIVE AGENTSCOMPUTATIONAL INTELLIGENCE, Issue 1 2005Jonathan Dinerstein The ability for a given agent to adapt on-line to better interact with another agent is a difficult and important problem. This problem becomes even more difficult when the agent to interact with is a human, because humans learn quickly and behave nondeterministically. In this paper, we present a novel method whereby an agent can incrementally learn to predict the actions of another agent (even a human), and thereby can learn to better interact with that agent. We take a case-based approach, where the behavior of the other agent is learned in the form of state,action pairs. We generalize these cases either through continuous k -nearest neighbor, or a modified bounded minimax search. Through our case studies, our technique is empirically shown to require little storage, learn very quickly, and be fast and robust in practice. It can accurately predict actions several steps into the future. Our case studies include interactive virtual environments involving mixtures of synthetic agents and humans, with cooperative and/or competitive relationships. [source] MUSEUMS AS AGENTS FOR SOCIAL AND POLITICAL CHANGE,CURATOR THE MUSEUM JOURNAL, Issue 3 2001DAWN CASEY First page of article [source] THE USE OF CONTRACT BY GOVERNMENT AND ITS AGENTSECONOMIC AFFAIRS, Issue 1 2009Martin Ricketts Given that the provision of a service is being controlled by the state, the decision whether to contract out that service provision to the private sector is essentially a business decision. A number of economic advantages and disadvantages need to be offset against each other. Governments are poorly placed to make such decisions and it is no surprise that PPPs are often inefficient and steered by political objectives. [source] ON THE PREFERENCES OF PRINCIPALS AND AGENTSECONOMIC INQUIRY, Issue 2 2010MARCO CASTILLO One of the reasons why market economies are able to thrive is that they exploit the willingness of entrepreneurs to take risks that laborers might prefer to avoid. Markets work because they remunerate good judgment and punish mistakes. Indeed, modern contract theory is based on the assumption that principals are less risk averse than agents. We investigate if the risk preferences of entrepreneurs are different from those of laborers by implementing experiments with a random sample of the population in a fast-growing, small-manufacturing, economic cluster. As assumed by theory, we find that entrepreneurs are more likely to take risks than hired managers. These results are robust to the inclusion of a series of controls. This lends support to the idea that risk preferences is an important determinant of selection into occupations. Finally, our lotteries are good predictors of financial decisions, thus giving support to the external validity of our risk measures and experimental methods (JEL C93, D81, D86). [source] EDUCATING COMMUNAL AGENTS: BUILDING ON THE PERSPECTIVISM OF G.H. MEADEDUCATIONAL THEORY, Issue 4 2007Jack Martin In this essay, Jack Martin aims to remedy such oversight by interpreting Mead's social-psychological and educational theorizing of selfhood and agency through the lenses of the perspectival realism Mead developed in the last decade of his life. This interpretation understands education as concerned with the cultivation and coordination of cultural, societal, interpersonal, and personal perspectives. Within this framework, communal agency is understood as a self-interpreting, self-determining capability of persons. This agentive capability derives from immersion and participation with others within sociocultural practices and perspectives, but also includes reactivity to those same practices and perspectives. The education of communal agents as envisioned here emphasizes the social nature of education, students' experience and development, and the critical role of the teacher as a mediator between student development and social process. Such an education is grounded in the immediate experiences and perspectives of learners, but increasingly assists learners to move beyond their own experiences through engaged interaction with others and with resources for acquiring broader, more organized perspectives on themselves, others, and the world. [source] SCREENING ETHICS WHEN HONEST AGENTS CARE ABOUT FAIRNESS*INTERNATIONAL ECONOMIC REVIEW, Issue 1 2006Ingela Alger A principal faces an agent with private information who is either honest or dishonest. Honesty involves revealing private information truthfully if the probability that the equilibrium allocation chosen by an agent who lies is small enough. Even the slightest intolerance for lying prevents full ethics screening whereby the agent is given proper incentives if dishonest and zero rent if honest. Still, some partial ethics screening may allow for taking advantage of the potential honesty of the agent, even if honesty is unlikely. If intolerance for lying is strong, the standard approach that assumes a fully opportunistic agent is robust. [source] PRIVATIZATION AND EFFICIENCY: FROM PRINCIPALS AND AGENTS TO POLITICAL ECONOMYJOURNAL OF ECONOMIC SURVEYS, Issue 4 2008Alberto Cavaliere Abstract We survey the theoretical literature on privatization and efficiency by tracing its evolution from the applications of agency theory to recent contributions in the field of political economy. The former extend the theory of regulation with incomplete information to address privatization issues, comparing state-owned enterprises with private regulated firms. The benefits of privatization may derive either from the constraints it places on malevolent agents or from the impossibility of commitment by a benevolent government because of incomplete contracts. Contributions dealing with political economy issues separate privatization from restructuring decisions. They either explore bargaining between managers and politicians or analyse the impact of privatization shaped by political preferences on efficiency. The theoretical results regarding the relation between privatization and efficiency do not lead to any definitive conclusion. Privatization may increase productive efficiency when restructuring takes place whereas its effects on allocative efficiency still remain uncertain. [source] USE OF CLARIFYING AGENTS AND ULTRA FILTER TO DECREASE FUMARIC ACID, HMF AND INCREASE CLARITY OF APPLE JUICEJOURNAL OF FOOD QUALITY, Issue 3 2006YAHYA TULEK ABSTRACT In this study, the effects of eight different processing treatments of apple juice (AJ) production (Process 1: Ultra filtration [UF], Process 2: Activated charcoal [AC], Process 3: polyvinylpolypyrolidone [PVPP], Process 4: Gelatine [G] + Bentonite [B], Process 5: [G + B] + UF, Process 6: [G + B] + AC, Process 7: [G + B] + PVPP and Process 8: [G + B] + Kieselguhr [K]) on the fumaric acid (FA), hydroxymethylfurfural (HMF), color and clearness values of AJ were investigated. With the exception of Processes 1 and 5, AC, K, PVPP, G and B were used at various doses in other processes. FA, HMF, color and clearness values of control sample were determined as 3.24 mg/L, 3.84 mg/L, 48.5 (%T) and 94.1 (%T), respectively. The highest proportional decrement in FA and HMF values of the samples were observed with Process 6 at the level of 5. The fifth level of Process 6 resulted in 35.8% (3.24,2.08 mg/L) and 35.9% (3.84 to 2.46 mg/L) reductions in FA and HMF values, respectively. On the other hand, the best improvement in clearness of AJ was obtained with Process 6 at the fourth level and obtained as 98.9 (%T). [source] THE INFLUENCE OF SOLUTION VISCOSITY AND DIFFERENT VISCOSIFYING AGENTS ON APPLE JUICE FLAVORJOURNAL OF SENSORY STUDIES, Issue 3 2000SHANE WALKER ABSTRACT Viscosifying agents are used in foods as thickeners to produce improved mouthfeel and as stabilizers to prevent settling out of particulate matter. While viscosifying agents are also known to influence the sensory profile of the products in which they are used, previous studies have examined the effects of viscosifying agents at levels that are not typical of those used in foods. The current study used a descriptive analysis panel to examine the effects of both viscosity and viscosifying agent on the sensory properties of apple juice using three viscosifying agents (carboxymethylcellulose, xanthan and pectin) at levels of usage similar to those recommended for drink products. Gas chromatography-flame ionization detection and gas chromatography-mass spectrometry were conducted on the samples to relate alteration in physico-chemical parameters to changes in sensory profile. Results from the descriptive panel showed that increasing viscosity tended to decrease some aspects of flavor intensity (sourness and cooked apple odor). Individual viscosifying agents were shown to have specific effects on odor and flavor attributes, e.g. pectin enhanced cereal odor. Gas chromatography-flame ionization detection and mass spectrometry suggested that this effect was related to isopropyl alcohol contributed by the pectin in solution. Pectin also suppressed honey odor and flavor, lemon odor and cooked apple flavor. [source] EFFECTS OF INULIN AND BULKING AGENTS ON SOME PHYSICOCHEMICAL, TEXTURAL AND SENSORY PROPERTIES OF MILK CHOCOLATEJOURNAL OF TEXTURE STUDIES, Issue 5 2009HANNANEH FARZANMEHR ABSTRACT Chocolates are favorite foodstuffs with high sugar contents. Therefore, in the present study, the production of a low-sugar milk chocolate with prebiotic properties is evaluated. Various ratios of inulin (IN), polydextrose (PD) and maltodextrin (MD) along with sucralose (0.04% w/w) were used instead of sugar. Fifteen formulations were examined to determine some physicochemical, mechanical and sensory properties in order to find their optimum ratios. In general, formulations with high ratios of PD and MD were moister and softer than control. The lowest moisture content and highest hardness were observed for the moderate ratios. In addition, MD induced the least desirable sensorial effects, whereas PD and IN pronouncedly improved the overall acceptability. The optimum applicable range for IN, PD and MD were 14,32% and 71,84%, 7,26% and 67,77%, and 0,20% of sugar substitutes, respectively. Our findings on simultaneous fat and sugar reductions also indicated the possibility of fat cut up to 5% in comparison to previous fat content. PRACTICAL APPLICATIONS In this paper, we have reported the influences of inulin (IN) as a prebiotic as well as polydextrose (PD) and maltodextrin (MD) as bulking agents on physicochemical, energy content, texture and sensory properties of milk chocolate using simplex lattice mixture design. To the best of our knowledge, this is the first report in this field with very interesting results and practical applicability. Moreover, our findings showed that the use of aforementioned ingredients instead of sugar could lead to production of low-calorie milk chocolate without having the undesirable textural and physiological effects on the product and consumers. Moreover, the simplex lattice mixture design was found a very useful technique for finding optimum ratios of sugar replacers in formulation. [source] THE LIQUIDITY TRAP AND PERSISTENT UNEMPLOYMENT WITH DYNAMIC OPTIMIZING AGENTS: EMPIRICAL EVIDENCETHE JAPANESE ECONOMIC REVIEW, Issue 4 2004YOSHIYASU ONO Standard money-in-utility dynamic models assume satiable liquidity preference, and thereby prove the existence of a full-employment steady state. In the same framework, it is known that under insatiable liquidity or wealth preference there is a case where a full-employment steady state does not exist. A liquidity trap then arises and unemployment persists in the steady state. Using both parametric and non-parametric methods, this paper empirically finds that insatiable liquidity/wealth preference is better supported. Thus, without assuming any permanent distortion, we can analyse an effective demand shortage in a dynamic optimization framework. [source] CRITICAL NOTICE OF LUCY O'BRIEN, SELF-KNOWING AGENTSANALYTIC PHILOSOPHY, Issue 4 2009JOHANNES ROESSLER First page of article [source] ANABOLIC AGENTS FOR IMPROVING MUSCLE REGENERATION AND FUNCTION AFTER INJURYCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 7 2008Gordon S Lynch SUMMARY 1In the present review, we describe how muscles can be injured by external factors, internal factors or during the performance of some actions during sports. In addition, we describe the injury to a muscle that occurs when its blood supply is interrupted, an occurrence common in clinical settings. An overview of muscle regeneration is presented, as well as a discussion of some of the potential complications that can compromise successful muscle repair and lead to impaired function and permanent disability. 2Improving muscle regeneration is important for hastening muscle repair and restoring muscle function and the present review describes ways in which this can be achieved. We describe recent advances in tissue engineering that offer considerable promise for treating muscle damage, but highlight the fact that these techniques require rigorous evaluation before they can become mainstream clinical treatments. 3Growth-promoting agents are purported to increase the size of existing and newly regenerating muscle fibres and, therefore, could be used to improve muscle function if administered at appropriate times during the repair process. The present review provides an update on the efficacy of some growth-promoting agents, including anabolic steroids, insulin-like growth factor-I (IGF-I) and b2 -adrenoceptor agonists, to improve muscle function after injury. Although these approaches have clinical merit, a better understanding of the androgenic, IGF-I and b-adrenoceptor signalling pathways in skeletal muscle is important if we are to devise safe and effective therapies to enhance muscle regeneration and function after injury. [source] ON SOCIAL LEARNING AND ROBUST EVOLUTIONARY ALGORITHM DESIGN IN THE COURNOT OLIGOPOLY GAMECOMPUTATIONAL INTELLIGENCE, Issue 2 2007Floortje Alkemade Agent-based computational economics (ACE) combines elements from economics and computer science. In this article, the focus is on the relation between the evolutionary technique that is used and the economic problem that is modeled. In the field of ACE, economic simulations often derive parameter settings for the genetic algorithm directly from the values of the economic model parameters. This article compares two important approaches that are dominating in ACE and shows that the above practice may hinder the performance of the genetic algorithm and thereby hinder agent learning. More specifically, it is shown that economic model parameters and evolutionary algorithm parameters should be treated separately by comparing the two widely used approaches to social learning with respect to their convergence properties and robustness. This leads to new considerations for the methodological aspects of evolutionary algorithm design within the field of ACE. [source] Agent-Based Interoperability without Product Model StandardsCOMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 2 2007Udo Kannengiesser A major problem with standard translators is that a seamless data transfer instantly fails when not every translator implements a mapping into or from the standard format. This is frequently the case for large design projects that involve the use of a multitude of heterogeneous tools, possibly in evolving configurations over time. The agent-based approach developed and presented in this article aims to flexibly provide product models in a form adapted to the needs of the particular tools when there is no prior agreement on a common data format. Experiments show the feasibility of this approach as well as its efficacy and efficiency. [source] Impact of mixed-parallelism on parallel implementations of the Strassen and Winograd matrix multiplication algorithmsCONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 8 2004F. Desprez Abstract In this paper we study the impact of the simultaneous exploitation of data- and task-parallelism, so called mixed-parallelism, on the Strassen and Winograd matrix multiplication algorithms. This work takes place in the context of Grid computing and, in particular, in the Client,Agent(s),Server(s) model, where data can already be distributed on the platform. For each of those algorithms, we propose two mixed-parallel implementations. The former follows the phases of the original algorithms while the latter has been designed as the result of a list scheduling algorithm. We give a theoretical comparison, in terms of memory usage and execution time, between our algorithms and classical data-parallel implementations. This analysis is corroborated by experiments. Finally, we give some hints about heterogeneous and recursive versions of our algorithms. Copyright © 2004 John Wiley & Sons, Ltd. [source] Feminist Theory, Embodiment, and the Docile Agent: Some Reflections on the Egyptian Islamic RevivalCULTURAL ANTHROPOLOGY, Issue 2 2001Saba Mahmood First page of article [source] Real Time Myocardial Contrast Echocardiography During Supine Bicycle Stress and Continuous Infusion of Contrast Agent.ECHOCARDIOGRAPHY, Issue 6 2007Cutoff Values for Myocardial Contrast Replenishment Discriminating Abnormal Myocardial Perfusion Background: Myocardial contrast echocardiography (MCE) is a new imaging modality for diagnosing coronary artery disease (CAD). Objective: The aim of our study was to evaluate feasibility of qualitative myocardial contrast replenishment (RP) assessment during supine bicycle stress MCE and find out cutoff values for such analysis, which could allow accurate detection of CAD. Methods: Forty-four consecutive patients, scheduled for coronary angiography (CA) underwent supine bicycle stress two-dimensional echocardiography (2DE). During the same session, MCE was performed at peak stress and post stress. Ultrasound contrast agent (SonoVue) was administered in continuous mode using an infusion pump (BR-INF 100, Bracco Research). Seventeen-segment model of left ventricle was used in analysis. MCE was assessed off-line in terms of myocardial contrast opacification and RP. RP was evaluated on the basis of the number of cardiac cycles required to refill the segment with contrast after its prior destruction with high-power frames. Determination of cutoff values for RP assessment was performed by means of reference intervals and receiver operating characteristic analysis. Quantitative CA was carried out using CAAS system. Results: MCE could be assessed in 42 patients. CA revealed CAD in 25 patients. Calculated cutoff values for RP-analysis (peak-stress RP >3 cardiac cycles and difference between peak stress and post stress RP >0 cardiac cycles) provided sensitive (88%) and accurate (88%) detection of CAD. Sensitivity and accuracy of 2DE were 76% and 79%, respectively. Conclusions: Qualitative RP-analysis based on the number of cardiac cycles required to refill myocardium with contrast is feasible during supine bicycle stress MCE and enables accurate detection of CAD. [source] Enhanced Left Ventricular Endocardial Border Delineation with an Intravenous Injection of SonoVue, a New Echocardiography Contrast Agent:ECHOCARDIOGRAPHY, Issue 8 2000A European Multicenter Study The safety and efficacy of SonoVue (also referred to as BR1), a new contrast agent for delineating endocardial border of the left ventricle after intravenous administration, was assessed. Two hundred and eighteen patients with suspected coronary artery disease undergoing fundamental echocardiography for the assessment of left ventricle were enrolled in a prospective multicenter, single blind, cross-over study with random sequence allocation of four different doses of SonoVue. Endocardial border definition in the apical and parasternal views was scored as O = not visible, 1 = barely visible, and 2 = well visualized before and after contrast enhancement. Analysis was performed by two pairs of off-site observers. Safety of SonoVue was also assessed. Results of our study indicated that the mean improvements in the endocardial border visualization score were as follows: 3.1 ± 7.8 (95% CI, 2.5 and 3.7) for 0.5 ml, 3.4 ± 8.0 (95% CI, 2.8 and 4.0) for 1 ml, 3.4 ± 7.9 (95% CI, 2.8 and 4.0) for 2 ml, and 3.7 ± 8.0 (95% CI, 3.1 and 4.3) for 4 ml (P < 0.05 for all doses from baseline). Changes from baseline in endocardial visualization scores were also seen in the apical views (P < 0.05) and they were dose-dependent (P < 0.001). Similar enhancements of endocardial visualization scores were observed in the apical views in patients with suboptimal baseline echocardiographic images. Diagnostic confidence for assigning a score and image quality also were significantly better following contrast enhancement. No significant changes in the laboratory parameters and vital signs were noted following contrast enhancement, and the side effects were minimal. It was concluded that SonoVue is safe and effective in delineating endocardial border, including in patients with suboptimal baseline images. [source] Design of an Ultrasound Contrast Agent for Myocardial PerfusionECHOCARDIOGRAPHY, Issue 2000Michel Schneider Ph.D. Myocardial contrast echography (MCE) has been a major research objective in cardiovascular ultrasound for almost two decades. The design of a contrast agent fulfilling the needs of MCE requires taking into consideration a number of points: a basic decision has to be made whether a deposit agent or a free-flowing agent would be more appropriate and whether an agent active at low/medium mechanical index (MI) is preferable to an agent active only at high MI; only a small percentage of the cardiac output enters the coronary microcirculation, which means that highly sensitive bubble detection methods, such as harmonic imaging or pulse inversion, are needed; the low velocity of blood in the microcirculation that leads to extensive bubble destruction during imaging means that intermittent imaging and/or an agent active at low MI is (are) required; the duration of the contrast effect must be sufficient to allow a complete examination and is affected by the rate of contrast administration; the performance of the contrast agent should not be equipment-dependent. The ultimate goal in MCE is to be able to quantify blood flow in the various segments to determine if adequate oxygenation is achieved. Ultrasound-mediated bubble destruction followed by the measurement of bubble replenishment kinetics opens new perspectives for quantification. SonoVue is a free-flowing ultrasound contrast agent made of sulphur hexafluoride microbubbles stabilized by a highly elastic phospholipid monolayer. SonoVue is able to produce myocardial opacification at a wide range of acoustic pressures and in particular at Mis as low as 0.1. Its performance is not equipment-dependent. Good results for myocardial opacification have been observed in all animal species tested (dogs, minipigs, rabbits), using continuous as well as intermittent imaging. Trials are in progress to demonstrate the clinical utility of SonoVue for rest and stress perfusion studies, in particular for the diagnosis of CAD, the detection of myocardial infarction, the assessment of the success of interventions and myocardial viability, and the detection of hibernating myocardium. [source] Digital Analysis of Myocardial Contrast Echocardiography: A Clinical Study Using an Air-Filled Agent in Normal SubjectsECHOCARDIOGRAPHY, Issue 3 2000EDWARD A. GEISER M.D., F.A.C.C. The purpose of the present study was to determine whether direct digital image analysis would allow improved detection of myocardial contrast. Eighteen normal subjects were recruited and separated into two groups. In group 1, the time-brightness curves of the left ventricular cavity and three myocardial perfusion beds were formed from digitized video tape, with output power and imaging time as secondary variables. In group 2, curves constructed from direct polar digital data were compared, with fundamental and second harmonic image formation as variables. In group 1 subjects, using fundamental imaging, the area under the curve in the left ventricular cavity increased slightly with intermittent imaging. No consistent myocardial opacification was identified. In group 2 subjects, using intermittent imaging, the area under the myocardial curve and peak intensity increased with high output second harmonic imaging in the left anterior descending and right coronary artery regions. Intermittent, second harmonic imaging and digital processing can demonstrate myocardial contrast even with an air-filled agent. [source] Extending drug ethno-epidemiology using agent-based modellingADDICTION, Issue 12 2009David Moore ABSTRACT Aims To show how the inclusion of agent-based modelling improved the integration of ethno-epidemiological data in a study of psychostimulant use and related harms among young Australians. Methods Agent-based modelling, ethnographic fieldwork, in-depth interviews and epidemiological surveys. Setting Melbourne, Perth and Sydney, Australia. Participants Club drug users in Melbourne, recreational drug users in Perth and street-based injecting drug users in Sydney. Participants were aged 18,30 years and reported monthly or more frequent psychostimulant use. Findings Agent-based modelling provided a specific focus for structured discussion about integrating ethnographic and epidemiological methods and data. The modelling process was underpinned by collective and incremental design principles, and produced ,SimAmph', a data-driven model of social and environmental agents and the relationships between them. Using SimAmph, we were able to test the probable impact of ecstasy pill-testing on the prevalence of harms,a potentially important tool for policy development. The study also navigated a range of challenges, including the need to manage epistemological differences, changes in the collective design process and modelling focus, the differences between injecting and non-injecting samples and concerns over the dissemination of modelling outcomes. Conclusions Agent-based modelling was used to integrate ethno-epidemiological data on psychostimulant use, and to test the probable impact of a specific intervention on the prevalence of drug-related harms. It also established a framework for collaboration between research disciplines that emphasizes the synthesis of diverse data types in order to generate new knowledge relevant to the reduction of drug-related harms. [source] Use of a Voltammetric Electronic Tongue for Detection and Classification of Nerve Agent MimicsELECTROANALYSIS, Issue 14 2010Inmaculada Campos Abstract An electronic tongue (ET) based on pulse voltammetry has been used to predict the presence of nerve agent mimics in aqueous environments. The electronic tongue array consists of eight working electrodes (Au, Pt, Ir, Rh, Cu, Co, Ni and Ag) encapsulated on a stainless steel cylinder. Studies including principal component analysis (PCA), artificial neural networks (fuzzy ARTMAP) and partial least square techniques (PLS) have been applied for data management and prediction models. For instance the electronic tongue is able to discriminate the presence of the nerve agent simulants diethyl chlorophosphate (DCP) and diethyl cyanophosphate (DCNP) from the presence of other organophosphorous derivatives in water. Finally, PLS data analysis using a system of 3 compounds and 3 concentration levels shows a good accuracy in concentration prediction for DCP and DCNP in aqueous environments. [source] | ||||||||||||||||||||||||||||||||||||||||||||||