System Experiences Research Articles

Model Reduction of Nonlinear Aeroelastic Systems Experiencing Hopf Bifurcation

In this paper, we employ the normal form to derive a reduced-order model that reproduces nonlinear dynamical behavior of aeroelastic systems that undergo Hopf bifurcation. As an example, we consider a rigid two-dimensional airfoil that is supported by nonlinear springs in the pitch and plunge directions and subjected to nonlinear aerodynamic loads. We apply the center manifold theorem on the governing equations to derive its normal form that constitutes a simplified representation of the aeroelastic system near flutter onset (manifestation of Hopf bifurcation). Then, we use the normal form to identify a self-excited oscillator governed by a time-delay ordinary differential equation that approximates the dynamical behavior while reducing the dimension of the original system. Results obtained from this oscillator show a great capability to predict properly limit cycle oscillations that take place beyond and above flutter as compared with the original aeroelastic system.

에이전트 행동에 기반한 의도 인식 컴퓨팅

에이전트의 의도를 인식하는 것은 사물지능형 컴퓨팅에서 인간컴퓨터 상호작용의 주요 부분이다. 컴퓨팅 시스템에서 인식 대상의 의도를 정확하게 유추하면 다수의 에이전트간의 협력 상황 이해와 특정 행동이 취해질 때의 상황 파악이 쉽기 때문이다. 본 연구는 다른 이의 행동을 해석하고 행동의 근거가 되는 의도와 목적을 추론하는 인간의 기제를 바탕으로, 컴퓨팅 시스템이 행동을 인식하여 습득한 사전 경험 데이터를 이용, 대상의 의도를 빠르게 인식하는 방법을 제안한다. 의도 인식을 수행하기 위해 제안 방법은 에이전트의 목적에 따른 행동 변화를 검출하고 시스템이 사전에 학습한 행동 정보를 모델링하기 위해 특정 형태의 행동 은닉마코프 형식을 이용한다. 에이전트의 의도를 추론하는 데 관점을 다양하게 취함으로써 시스템이 에이전트의 행동이 끝나기 전에 미리 의도를 추론하도록 한다. 의도 인식의 정확도, 조기 검출률과 정확 지속률에 대한 실험으로 여러 가지 행동을 취하는 에이전트의 의도 검출 결과를 정량적으로 제시함으로써 제안 연구가 효과적인 의도 인식 시스템 구현에 기여함을 보여준다. Understanding agent's intent is an essential component of the human-computer interaction of ubiquitous computing. Because correct inference of subject's intention in ubiquitous computing system helps particularly to understand situations that involve collaboration among multiple agents or detection of situations that can pose a particular activity. This paper, inspired by people have a mechanism for interpreting one another's actions and for inferring the intentions and goals that underlie action, proposes an approach that allows a computing system to quickly recognize the intent of agents based on experience data acquired through prior capabilities of activities recognition. To proceed intention recognition, proposed method uses formulations of Hidden Markov Models (HMM) to model a system's prior experience and agents' action change, then makes for system infer intents in advance before the agent's actions are finalized while taking the perspective of the agent whose intent should be recognized. Quantitative validation of experimental results, while presenting an accurate rate, an early detection rate and a correct duration rate with detecting the intent of several people performing various activities, shows that proposed research contributes to implement effective intent recognition system.

Prescription Acetaminophen Ingestions Associated with Hepatic Injury and Death

The U.S. Food and Drug Administration has formally requested that pharmaceutical manufacturers limit the amount of acetaminophen (APAP) in prescription products. The goal of this study was to describe a state-wide poison control system's experience with prescription APAP ingestions that resulted in hepatic injury or death. Retrospective analysis of statewide California Poison Control System electronic database for cases from the years 2000 through 2009. adults ≥18 years of age following therapeutic use of an acetaminophen-containing prescription with laboratory evidence of liver injury. Forty cases met the inclusion criteria. All cases involved at least two concurrent acetaminophen-containing products. Prescription APAP strengths of 500 mg per tablet or greater were involved in 32 of 40 cases (80 %). Thirty patients survived, three died, one underwent liver transplantation and seven cases were lost to follow up. The ingestion of concentrated prescription APAP-containing medications in combination with other sources of APAP can result in severe liver injury and death. Limiting the amount of APAP from prescription medications in conjunction with enhanced prescriber and patient education regarding the hazards of ingesting multiple APAP-containing products may assist in decreasing the overall incidence of unintentional APAP poisonings in the United States. Future prospective studies are required to determine if these measures will have a significant impact on both the morbidity and mortality associated with APAP administration.

Thinking Strategically: Academic–Practice Relationships: One Health System's Experience

Strategic planning and joint leverage of the strengths inherent in the academic and practice arenas of nursing are imperative to confront the challenges facing the profession of nursing and its place within the healthcare team of the future. This article presents a description and discussion of the implementation of several academic-practice partnership initiatives by Meridian Health, a health system located in central New Jersey. Included in the strategies discussed are creation of a support program for nonprofessional employees to become registered nurses; active partnership in the development of an accelerated BSN program; construction of support systems and academic partnerships for staff participation in RN-to-BSN programs; construction of on-site clinical simulation laboratories to foster interprofessional learning; and the implementation of a new BSN program, the first and only generic BSN program in two counties of the state. Outcomes of these academic-practice partnerships also are presented, including number of participants; graduation and NCLEX-RN pass rates; MH nurse vacancy rates; and nurse retention rates after first employment.

Prehospital Administration of Tenecteplase for ST-segment Elevation Myocardial Infarction in a Rural EMS System

Introduction. In the setting of ST-segment elevation myocardial infarction (STEMI), early reperfusion yields better patient outcomes. Emergency medical services (EMS) is the first medical contact for half of the afflicted population, and prehospital thrombolysis may result in considerably faster reperfusion compared with percutaneous coronary intervention (PCI) in rural settings. However, there are few reports of prehospital thrombolysis in rural EMS systems. Objective. To describe a rural EMS system's experience with tenecteplase in STEMI. Methods. Data were retrospectively abstracted from the medical records of patients receiving tenecteplase using standard chart review guidelines. Primary outcomes included time saved by EMS-initiated thrombolysis, aborted infarctions, serious bleeding events, and in-hospital mortality. Secondary outcomes included reinfarction, rescue angioplasty, and appropriateness of treatment. Time savings was defined as transport time after tenecteplase administration plus 90 minutes, which is the typical door-to-balloon time for PCI laboratories. Aborted infarction was defined as resolution of the cumulative ST-segment elevation to ≤50% of that on the initial electrocardiogram (ECG) within two hours after treatment, and peak creatine kinase (CK)/CK-MB levels less than or equal to twice the upper limit of normal. Results. Seventy-three patients received prehospital tenecteplase; this treatment was determined to be appropriate in 86.4% of cases. The mean patient age was 59 years, and 71.6% of the patients were male. Mean (± standard deviation) scene-arrival-to-drug time was 26.2 (±11.4) minutes, the mean scene-arrival-to-hospital-arrival time was 73.0 (±20.6) minutes, and the mean transport time was 46.0 (± 11.1) minutes. Tenecteplase was administered 35.9 (±25.0) minutes prior to hospital arrival, and the estimated reperfusion time savings over PCI was 125.9 (±25.0) minutes. Aborted infarctions were observed in 24.1% of patients, whereas 9.6% suffered reinfarction, 47.9% underwent rescue angioplasty, and 16.7% required coronary artery bypass grafting (CABG). Serious bleeding events occurred in 15 patients (20.5%), and four (5.5%) died. Conclusion. In this retrospective review of rural STEMI patients, tenecteplase was administered 36 minutes prior to hospital arrival, saving approximately two hours over typical PCI strategies and resulting in aborted infarctions in one-fourth of patients. In a rural setting with lengthy transport times to PCI facilities, tenecteplase appears to be a feasible prehospital intervention. Randomized controlled trials are needed to fully evaluate the safety and effectiveness of this intervention prior to widespread adoption.

Using Desired Culture Analysis to Manage Decentralized Operations

:The purpose of this article is to extract lessons and implications for managers in decentralized operations who seek to integrate their organizational culture across all operations. This is accomplished via a case study of the role of culture measurement and resultant action planning in a regional healthcare system in the midwest United States. The system's vision was to provide a seamless patient experience everywhere in the system. Managers in engineering and technical organizations having decentralized functions can learn from this system's experience in using culture measurement to support organizational system integration.

Epidemiology of Pediatric Transports andNon-Transports in an Urban Emergency Medical Services System

Objective. This study was done to describe an urban, Emergency Medical Service (EMS) system's experiences with pediatric patients andthe rate andcharacteristics of non-transports in this setting. Methods. A retrospective analysis of all pediatric patients responded to by the Detroit Fire Department Division of EMS between January 1, 2002 andAugust 30, 2002 was done. Results. There were 5,976 pediatric EMS cases. Children 10 years of age or older accounted for 49.4% of transports, 53.8% of all patients had medical illness, and38.8% of the patients belonged to the non-urgent category. A large percentage of patients were not transported (27.2%), most commonly secondary to parent/caregiver/patient refusals. The median number of minutes on-scene for refusals was longer than for transports (23.5 vs. 17.3, respectively)[difference = 6.2 minutes (95% CI: 5.6–6.9)]. The odds ratios (OR) for refusal was highest for assaults (2.09; 95% CI: 1.66–2.63), difficulty in breathing (1.38; 95% CI: 1.14–1.68), andmotor vehicle accidents (1.19; 95% CI: 1.04–1.37). Conclusions. In this system, the majority of pediatric patients are not severely ill, anda large number are not transported. Non-transports are more likely to be young adolescents, have been involved in assaults, andhave a longer on-scene time.

Playing to Learn: Case-Injected Genetic Algorithms for Learning to Play Computer Games

We use case-injected genetic algorithms (CIGARs) to learn to competently play computer strategy games. CIGARs periodically inject individuals that were successful in past games into the population of the GA working on the current game, biasing search toward known successful strategies. Computer strategy games are fundamentally resource allocation games characterized by complex long-term dynamics and by imperfect knowledge of the game state. CIGAR plays by extracting and solving the game's underlying resource allocation problems. We show how case injection can be used to learn to play better from a human's or system's game-playing experience and our approach to acquiring experience from human players showcases an elegant solution to the knowledge acquisition bottleneck in this domain. Results show that with an appropriate representation, case injection effectively biases the GA toward producing plans that contain important strategic elements from previously successful strategies.

Evaluation of “Depression in Primary Care” Innovations

Key stakeholders and executive decision makers in health care system require clear and convincing data of the value of chronic illness care models for the primary care treatment of depression. Well-conceived and conducted evaluations provide this necessary information. This case study describes the experience of a large, nonprofit health care system's experience with implementing and evaluating a quality improvement program for integrating depression management into primary care. The commentary that follows discusses specific evaluation questions that are relevant to each of the stakeholder groups involved in deciding whether or not to continue supporting such programs.

Special Section on Seclusion and Restraint: Introduction to the Special Section

Special Section on Seclusion and Restraint: Introduction to the Special Section

Implementing the Hospital Emergency Incident Command System: An Integrated Delivery System's Experience

Hospital disaster manuals and response plans often lack formal command structure; instead, they rely on the presence of key individuals who are familiar with hospital operations, or who are in leadership positions during routine, day-to-day operations. Although this structure occasionally may prove to be successful, it is unreliable, as this leadership may be unavailable at the time of the crisis, and may not be sustainable during a prolonged event. The Hospital Emergency Incident Command System (HEICS) provides a command structure that does not rely on specific individuals, is flexible and expandable, and is ubiquitous in the fire service, emergency medical services, military, and police agencies, thus allowing for ease of communication during event management. A descriptive report of the implementation of the HEICS throughout a large healthcare network is reviewed. Implementation of the HEICS provides a consistent command structure for hospitals that enables consistency and commonality with other hospitals and disaster response entities.

PROBLEM SOLVING WITH INSUFFICIENT RESOURCES

A new approach, "controlled concurrency," is introduced for inference control in an adaptive reasoning system working with insufficient knowledge and resources. With this method, a problem-solving process is constructed from atomic steps in run time, according to the system's past experience and the current context. The system carries out many such processes in parallel by distributing its resources among them, and dynamically adjusting the distribution according to feedback. A data structure, "bag," is designed to support this dynamic time-space allocation, and is a kind of probabilistic priority queue. This approach provides a flexible, efficient, and adaptive control mechanism for real-time systems working with uncertain knowledge. To analyze problem solving in such a system, the traditional computability theory and computational complexity theory become inappropriate, because the system no longer follows problem-specific algorithms in problem solving.

Distinctiveness magnifies the impact of biological invaders in aquatic ecosystems

AbstractThere exist few empirical rules for the effects of introduced species, reflecting the context‐dependent nature of biological invasions. A promising approach toward developing generalizations is to explore hypotheses that incorporate characteristics of both the invader and the recipient system. We present the first general test of the hypothesis that an invader's impact is determined by the system's evolutionary experience with similar species. Through a meta‐analysis, we compared the taxonomic distinctiveness of high‐ and low‐impact invaders in several aquatic systems. We find that high‐impact invaders (i.e. those that displace native species) are more likely to belong to genera not already present in the system.

Managing drug shortages: seven years' experience at one health system.

A health system's experience in monitoring drug shortages since 1996 within the organization and since 2001 on a national level is described. Since January 1996, the Drug Information Service (DIS) at the University of Utah Hospitals and Clinics (UUHSC) has systematically prepared written bulletins to affected practitioners when drug shortages occurred. The DIS began providing information on a national level to the American Society of Health-System Pharmacists in January 2001. A total of 224 drug shortages were tracked from January 1996 to June 2002. All shortages at UUHSC were also national shortages, but only about two thirds of national shortages also affected UUHSC. The most common reasons for shortages were manufacturing problems (28%) and product discontinuation (20%). The most frequently represented pharmacologic-therapeutic categories were central nervous system agents (24%) and serums, toxoids, and vaccines (17%). Of the 119 shortages in 2001, 70 (59%) were still ongoing as of the end of June 2002. The most common potential safety problems were that clinicians might be unfamiliar with the alternative agent (54%) and that the alternative's dosage requirement was different (50%). Over half of the shortages were cost neutral, but the assessment did not include substantial potential indirect costs. Detailed information on drug shortages collected by a health system's drug information service since 1996 indicated a trend toward more frequent shortages.

Breaking out of the silo: one health system's experience.

Pharmacoeconomic evidence for inpatient deep vein thrombosis (DVT) treatment with low-molecular-weight heparins (LMWHs) and one health system's experience with this treatment compared with unfractionated heparins (UFHs) are examined. Applying clinical and pharmacoeconomic evidence to clinical practice can be challenging, especially when using high-cost therapies, because of the limited financial resources of health systems. While LMWHs have higher acquisition costs, they offer several advantages over UFHs, contributing to their overall pharmacoeconomic value. Inpatient treatment of DVT with LMWHs has not been widely adopted, despite the clinical evidence supporting their use, partly because of the up-front cost of these medications. A cost-minimization analysis was performed to estimate the cost impact of switching from UFHs to LMWHs for inpatient treatment of DVT at the Detroit Medical Center (DMC). The costs of once- and twice-daily administration of enoxaparin were compared with those of UFH. The costs of medications, laboratory tests, and pharmacist time were calculated. Costs for hospital stay and medical fees were assumed to be similar among all treatment groups. The annual cost for DVT treatment for the entire DMC was then estimated using pharmacoeconomic modeling and Monte Carlo simulation. Inpatient UFH costs totaled $138,580, once-daily LMWHs were $177,531, and twice-daily LMWHs cost $205,569 for 500 patients with primary DVT. Treatment with LMWHs cost $20-$34 more per patient per day than UFHs, but incurred savings by reducing readmission and reocclusion rates. LMWHs are a cost-effective treatment for DVT, from both a third-party-payer and a societal perspective.

Can Western Quality Improvement Methods Transform the Russian Health Care System?

The Russian health care system largely remains the same system that was in place during the existence of the Soviet Union. It is almost entirely state owned and operated, although ownership and management have developed from the central government to the oblast (province). The ZdravReform (Health Reform) Program (ZRP) in Russia, which began in 1993, included the goal of improving the quality and cost-effectiveness of the health care system. Work on introducing continuous quality improvement (CQI), evidence-based practice guidelines, and indicators of quality was conducted in 1995-1996. INTRODUCING EVIDENCE-BASED MEDICINE: As a result of the poor quality of Russian-language medical journals and the inability to gain access to the knowledge available in Western medical literature, Russian medical practices have not kept up with the rapid evolution of evidence-based medical practice that has begun transforming Western medicine. A number of evidence-based clinical practice guidelines were translated and disseminated to Russian-speaking physicians working in facilities participating in ZRP in Russia and Central Asia. Given the limitations of existing measures of the quality of care, indicators were developed for participating ambulatory polyclinics in several oblasts in Siberia. Russian physicians responsible for quality of care for their respective oblasts formed a working group to develop the indicators. A clinical information system that would provide automated collection and analysis of the indicator data-as well as additional patient record information-was also developed. CQI activities, entailing a multidisciplinary, participatory team approach, were conducted in four oblasts in western Siberia. Projects addressed the management of community-acquired pneumonia and reduction of length of stay after myocardial infarction (MI). One of the oblasts provided an example of a home-grown evidence-based protocol for post-MI care, which was adopted in the other three oblasts. Evidence-based medicine is critically needed to improve the quality of research and publications, medical education, and medical practice. Physicians everywhere are data driven; they change their practices when convinced by good data. The key to successful introduction of evidence-based medicine is understanding the fundamentals of good scientific method as applied to medicine. The Russian health care system's experience in reporting to higher authorities' process and outcomes data that resemble our modern indicators can provide the basis for accurate and valid measures of quality. In contrast with American expectations that a significant cultural change in an organization could take years, even with great effort, Russian physicians and other clinicians rapidly assimilated the new concepts of QI and put them to use. More on-site assistance by international medical consultants will still be needed for several years to hasten the process of change and ensure that it does not become stalled.

Lessons Learned from Programs for Unaccompanied Refugee Minors

SUMMARY A policy for priority admissions and subsequent care of unaccompanied refugee entrant minors was established in 1978 in response to the influx of Southeast Asian refugee minors. This article describes the child welfare system's response and workers' experiences in meeting the needs of this population. Lessons learned can be applied to permanency planning for children from varying cultural backgrounds.

QUEM: an achievement test for knowledge-based systems

This paper describes the Quality and Experience Metric (QUEM), a method for estimating the skill level of a knowledge based system based on the quality of the solutions it produces. It allows one to assess how many years of experience the system would be judged to have if it were a human by providing a quantitative measure of the system's overall competence. QUEM can be viewed as a type of achievement or job placement test administered to knowledge based systems to help system designers determine how the system should be used and by what level of user. To apply QUEM, a set of subjects, experienced judges, and problems must be identified. The subjects should have a broad range of experience levels. Subjects and the knowledge based system are asked to solve the problems; and judges are asked to rank order all solutions, from worst quality to best. The data from the subjects is used to construct a skill function relating experience to solution quality, and confidence bands showing the variability in performance. The system's quality ranking is then plugged into the skill function to produce an estimate of the system's experience level. QUEM can be used to gauge the experience level of an individual system, to compare two systems, or to compare a system to its intended users. This represents an important advance in providing quantitative measures of overall performance that can be applied to a broad range of systems.

A Price Target for U.S. Monetary Policy? Lessons from the Experience with Money Growth Targets

The cutting edge of recent efforts to reshape monetary policy in many countries has been to impose a price target on the central bank. This paper examines such a policy in light of the Federal Reserve System's experience with money targeting from the late 1970s through the mid 1980s. The empirical analysis documents the Federal Reserve's initial use and subsequent disregard of money growth targets, and shows that abandoning these targets was a sensible response to the changing mix of shocks affecting the U.S. economy -- specifically, an increase in the relative volatility of money demand shocks. This experience provides little ground for confidence that a price target would be optimal for U.S. monetary policy. Even if the structure of the relevant shocks at any particular time were to appear favorable, a policy based on a price target would likewise be undermined if the relative volatility of aggregate supply shocks increased.(This abstract was borrowed from another version of this item.)

Dispersive mixing in immiscible polymer blends

AbstractDispersive mixing of immiscible polymer blends as well as polymer systems containing solids is achieved in compounding equipment at two stages of the system's processing experience: first, while one or more of the polymer components are melting, and second, after all polymer components have melted. That is, the first mode of dispersive mixing occurs during the melting mechanism of “dissipative mix melting” (Ref. 1), while the second is melt‐melt mixing.During the compounding of a given blend system, there are a number of processing parameters that can be changed in order to improve mixing. These range from machine operating variables to the addition of processing aids. If such processing changes fail to produce the desired morphology, the most common change to consider is the screw geometry. This, in practice involves a trial and error procedure, or the use of an existing database built from prior experience.The role which the thermomechanical and rheological properties of the blend component play in dissipative mix melting and melt‐melt mixing has not yet been well understood. The reason for this is that although most blend systems have components which are strongly non‐Newtonian and strongly viscoelastic, the thinking and rules of thumb for mixing such materials has been heavily influenced by the analysis of G. I. Taylor (Ref. 2), who in 1932 addressed the phenomenon of the dispersion of a single Newtonian droplet by a Newtonian matrix flowing in laminar shear flow.This paper addresses the strong role that the rheology of blend components, under processing conditions, play in laminar dispersive mixing of polymer blends. From a practical point of view, if the dispersion mechanisms and rates of dispersion depend on the component rheology, then such knowledge can lead us to the selection of advantageous mixing element designs and processing conditions.The experimental results were obtained in dispersive mixing carried out in devices developed in the Polymer Mixing Study (Ref. 3). Such model devices include the Couette Flow Intensive Mixer (CIM) (Ref. 4), where a constant shear stress is applied on the blend components and the Twin Screw Mixing Element Evaluator (TSMEE) (Ref. 5), where the mixing flows are those encountered in actual mixing/compounding operations. The TSMEE will be described in the body of this paper together with its on‐ and off‐line morphology determination capabilities and its in‐line rheology sensor.The low‐density polyethylene (LDPE) and polystyrene (PS) polymers studied were selected because they cover a wide spectrum of rheological properties.