Coronary artery grafting in infants

Coronary artery bypass grafting (CABG) with cardiac vale repair is an uncommon surgery in infants. CABG is technically demanding in infants due to the small size not only of the coronary arteries but also the potential graft arteries. The short and long-term outcome of surgery is not known and thus has largely been avoided. This article reports the case histories of two infants in whom CABG was undertaken successfully as a life-saving measure.peer-reviewe

Exponential approximations in optimal design

One-point and two-point exponential functions have been developed and proved to be very effective approximations of structural response. The exponential has been compared to the linear, reciprocal and quadratic fit methods. Four test problems in structural analysis have been selected. The use of such approximations is attractive in structural optimization to reduce the numbers of exact analyses which involve computationally expensive finite element analysis

Using the analytic hierarchy process in group decision making for nuclear spare parts

University of Pittsburgh, University of Arkansas, The Analytic Hierarchy Process (AHP) is an established decision method used to synthesize judgments and select the best alternative. The AHP literature extensively discusses both theory and case studies for judgments made by one person. However, instances exist when the judgments of a group of individuals are needed for accurate knowledge representation and robust decision making. One such instance is spare parts processes for nuclear electricity plants. Elicitation of group knowledge is necessary because each work group may have different experiences and attitudes towards spare parts management. This paper presents an interview protocol used for group knowledge elicitation using AHP for nuclear spare parts inventory management. Inconsistencies in the data and challenges in AHP group aggregation are examined. A numerical example of employee responses is included. This research benefits the engineering manager by presenting a methodology to collect a range of knowledge across work groups. The authors' overall decision tool supports existing corporate culture while striving for continuous process improvement

Influence diagram modeling of nuclear spare parts process

Spare parts inventory levels at nuclear generation plants have neared all-time highs at some facilities. As part of an ongoing research project, the authors are developing a decision making framework for nuclear spare parts management. This paper describes the use of an influence diagram model to represent the existing spare parts process at a United States nuclear facility. We then discuss how this model can be extended to develop an interview protocol for subsequent data collection using the Analytic Hierarchy Process. The influence diagram drives the overall analysis of determining best practices for the spare parts process for continuous improvement

Decision making and tradeoffs in the management of spare parts inventory at utilities

During the past decade, the United States electric utility industry has migrated from a regulated to a deregulated business environment. As a result, utilities in the electric power sector face a much more urgent imperative to emphasize cost efficiencies as compared to the days of regulation. One major opportunity for cost savings is through reductions in spare parts inventory. Most utilities are accustomed to carrying large volumes of expensive, relatively slow-moving units because of a high degree of risk-averseness. In this paper we discuss the tradeoffs associated with keeping large amounts of inventory versus the potential revenue losses if a plant were to go off-line. We also discuss the resulting considerations with respect to inventory along with forecasting techniques and data needed to aid plant managers in making stocking decisions. Copyright© (2009) by the American Society for Engineering Management

Personal Navigation via High-Resolution Gait-Corrected Inertial Measurement Units

In this paper, a personal micronavigation system that uses high-resolution gait-corrected inertial measurement units is presented. The goal of this paper is to develop a navigation system that uses secondary inertial variables, such as velocity, to enable long-term precise navigation in the absence of Global Positioning System (GPS) and beacon signals. In this scheme, measured zerovelocity duration from the ground reaction sensors is used to reset the accumulated integration errors from accelerometers and gyroscopes in position calculation. With the described system, an average position error of 4 m is achieved at the end of half-hour walks

Personal Navigation via High-Resolution Gait-Corrected Inertial Measurement Units

In this paper, a personal micronavigation system that uses high-resolution gait-corrected inertial measurement units is presented. The goal of this paper is to develop a navigation system that uses secondary inertial variables, such as velocity, to enable long-term precise navigation in the absence of Global Positioning System (GPS) and beacon signals. In this scheme, measured zerovelocity duration from the ground reaction sensors is used to reset the accumulated integration errors from accelerometers and gyroscopes in position calculation. With the described system, an average position error of 4 m is achieved at the end of half-hour walks

Optimally Deceiving a Learning Leader in Stackelberg Games

Recent results have shown that algorithms for learning the optimal commitment in a Stackelberg game are susceptible to manipulation by the follower. These learning algorithms operate by querying the best responses of the follower, who consequently can deceive the algorithm by using fake best responses, typically by responding according to fake payoffs that are different from the actual ones. For this strategic behavior to be successful, the main challenge faced by the follower is to pinpoint the fake payoffs that would make the learning algorithm output a commitment that benefits them the most. While this problem has been considered before, the related literature has only focused on a simple setting where the follower can only choose from a finite set of payoff matrices, thus leaving the general version of the problem unanswered. In this paper, we fill this gap by showing that it is always possible for the follower to efficiently compute (near-)optimal fake payoffs, for various scenarios of learning interaction between the leader and the follower. Our results also establish an interesting connection between the follower’s deception and the leader’s maximin utility: through deception, the follower can induce almost any (fake) Stackelberg equilibrium if and only if the leader obtains at least their maximin utility in this equilibrium

Homozygosity for a missense mutation in the 67 kDa isoform of glutamate decarboxylase in a family with autosomal recessive spastic cerebral palsy: parallels with Stiff-Person Syndrome and other movement disorders

Background Cerebral palsy (CP) is an heterogeneous group of neurological disorders of movement and/or posture, with an estimated incidence of 1 in 1000 live births. Non-progressive forms of symmetrical, spastic CP have been identified, which show a Mendelian autosomal recessive pattern of inheritance. We recently described the mapping of a recessive spastic CP locus to a 5 cM chromosomal region located at 2q24-31.1, in rare consanguineous families. Methods Here we present data that refine this locus to a 0.5 cM region, flanked by the microsatellite markers D2S2345 and D2S326. The minimal region contains the candidate gene GAD1, which encodes a glutamate decarboxylase isoform (GAD67), involved in conversion of the amino acid and excitatory neurotransmitter glutamate to the inhibitory neurotransmitter γ-aminobutyric acid (GABA). Results A novel amino acid mis-sense mutation in GAD67 was detected, which segregated with CP in affected individuals. Conclusions This result is interesting because auto-antibodies to GAD67 and the more widely studied GAD65 homologue encoded by the GAD2 gene, are described in patients with Stiff-Person Syndrome (SPS), epilepsy, cerebellar ataxia and Batten disease. Further investigation seems merited of the possibility that variation in the GAD1 sequence, potentially affecting glutamate/GABA ratios, may underlie this form of spastic CP, given the presence of anti-GAD antibodies in SPS and the recognised excitotoxicity of glutamate in various contexts