139 research outputs found
Research opportunities in joint interoperability testing
The Department of Defense requires that all command, control, communications and computers intelligence (C4I) systems and automated information systems-(AIS) be interoperable between the services. The Joint Interoperability Test Command (JITC) is responsible for testing and certifying the joint interoperability of these systems. The design of joint interoperability tests and the analysis of data that they produce offer many opportunities for NPS faculty and students to collaborate with JITC on research projects of mutual interest. This paper outlines a spectrum of potential research opportunities, encompassing probability and statistics, modeling and simulation, computer science, information technology, electrical engineering, human factors, and specialized subject matter related to intelligence, communications, and missile defense systems
Estimating Total Program Cost of a Long-Term, High-Technology, High-Risk Project with Task Durations and Costs That May Increase Over Time
Military Operations Research, 11, 2006, pp. 41-62.We plan a long-term project schedule for which the total budget depends upon the year the project finishes. Each task in the project can begin only when all its predecessor tasks have been completed, and each task has a range of feasible durations with a month-by-month cost profile for each duration. A task start can be delayed, but once started for some chosen duration, a task cannot be interrupted. Each task suffers some risk of delay and changed cost. Ignoring budget constraints, we use Monte Carlo simulation of the duration of each task in the project to infer the probability distribution of the project completion time. We then optimize a deterministic project schedule following budget guidance. Finally, we successively reschedule as the project progresses, simulating annual review of the active tasks, and possibly delaying each active task's duration and changing its monthly costs for its forecast duration. We do not require an independence assumption, so we can accommodate learning effects from completed tasks. U.S. Army Future Combat Systems (FCS) is our motivating application. FCS is a complex of information technologies, sensors, and command systems expected to require more than a decade and $16 billion to develop. The U.S. General Accounting Office finds FCS at significant risk of cost and schedule growth, and suggests two alternatives to a baseline Army plan. We analyze these three alternate project plans for FCS to discover which one can most likely be completed soonest and cheapest
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Contemporary predictors of death and sustained ventricular tachycardia in patients with repaired tetralogy of Fallot enrolled in the INDICATOR cohort
Objective: Patients with repaired tetralogy of Fallot (TOF) experience increased rates of mortality and morbidity in adulthood. This study was designed to identify risk factors for death and ventricular tachycardia (VT) in a large contemporary cohort of patients with repaired TOF. Methods: Subjects with repaired TOF from four large congenital heart centres in the USA, Canada and Europe were enrolled. Clinical, ECG, exercise, cardiac magnetic resonance (CMR) and outcome data were analysed. Results: Of the 873 patients (median age 24.4 years), 32 (3.7%) reached the primary outcome (28 deaths, 4 sustained VT; median age at outcome 38 years; median time from CMR to outcome 1.9 years). Cox proportional-hazards regression identified RV mass-to-volume ratio ≥0.3 g/mL (HR, 5.04; 95% CI 2.3 to 11.0; p<0.001), LV EF z score<−2.0 (HR, 3.34; 95% CI 1.59 to 7.01; p=0.001), and history of atrial tachyarrhythmia (HR, 3.65; 95% CI 1.75 to 7.62; p=0.001) as outcome predictors. RV dysfunction was predictive of the outcome similar to LV dysfunction. In subgroup analysis of 315 subjects with echocardiographic assessment of RV systolic pressure, higher pressure (HR 1.39; 95% CI 1.19 to 1.62; p<0.001) was associated with death and sustained VT independent of RV hypertrophy and LV dysfunction. Conclusions: RV hypertrophy, ventricular dysfunction and atrial tachyarrhythmias are predictive of death and sustained VT in adults with repaired TOF. These findings may inform risk stratification and the design of future therapeutic trials
Mobile health in adults with congenital heart disease: Current use and future needs
Objective Many adults with congenital heart disease (CHD) are affected lifelong by cardiac events, particularly arrhythmias and heart failure. Despite the care provided, the cardiac event rate remains high. Mobile health (mHealth) brings opportunities to enhance daily monitoring and hence timely response in an attempt to improve outcome. However, it is not known if adults with CHD are currently using mHealth and what type of mHealth they may need in the near future. Methods Consecutive adult patients with CHD who visited the outpatient clinic at the Academic Medical Center in Amsterdam were asked to fill out questionnaires. Exclusion criteria for this study were mental impairment or inability to read and write Dutch. Results All 118 patients participated (median age 40 (range 18–78) years, 40 % male, 49 % symptomatic) and 92 % owned a smartphone. Whereas only a small minority (14 %) of patients used mHealth, the large majority (75 %) were willing to start. Most patients wanted to use mHealth in order to receive more information on physical health, and advice on progression of symptoms or signs of deterioration. Analyses on age, gender and complexity of defect showed significantly less current smartphone usage at older age, but no difference in interest or preferences in type of mHealth application for the near future. Conclusion The relatively young adult CHD population only rarely uses mHealth, but the majority are motivated to start using mHealth. New mHealth initiatives are required in these patients with a chronic condition who need lifelong surveillance in order to reveal if a reduction in morbidity and mortality and improvement in quality of life can be achieved
Identification of patients at risk of sudden cardiac death in congenital heart disease:The PRospEctiVE study on implaNTable cardlOverter defibrillator therapy and suddeN cardiac death in Adults with Congenital Heart Disease (PREVENTION-ACHD)
BACKGROUND Sudden cardiac death (SCD) is the main preventable cause of death in patients with adult congenital heart disease (ACHD). Since robust risk stratification methods are lacking, we developed a risk score model to predict SCD in patients with ACHD: the PRospEctiVE study on implaNTable cardlOverter defibrillator therapy and suddeN cardiac death in Adults with Congenital Heart Disease (PREVENTION-ACHD) risk score model. OBJECTIVE The purpose of this study was to prospectively study predicted SCD risk using the PREVENTION-ACHD risk score model and actual SCD and sustained ventricular tachycardia/ventricular fibrillation (VT/VF) rates in patients with ACHD. METHODS The PREVENTION-ACHD risk score model assigns 1 point each to coronary artery disease, New York Heart Association class II/III heart failure, supraventricular tachycardia, systemic ejection fraction = 120 ms, and QT dispersion >= 70 ms. SCD risk was calculated for each patient. An annual predicted risk of >= 3% constituted high risk. The primary outcome was SCD or VT/VF after 2 years. The secondary outcome was SCD. RESULTS The study included 783 consecutive patients with ACHD (n=239 (31%) left-sided lesions; n=138 (18%) tetralogy of Fallot; n=108 (14%) dosed atrial septal defect; median age 36 years; interquartile range 28-47 years; n=401 (51%) men). The PREVENTION-ACHD risk score modelidentified 58 high-risk patients. Eight patients (4 at high risk) experienced the primary outcome. The Kaplan-Meier estimates were 7% (95% confidence interval [CI] 0.1%-13.3%) in the high-risk group and 0.6% (95% CI 0.0%-1.1%) in the low-risk group (hazard ratio 12.5; 95% CI 3.1-50.9; P < .001). The risk score model's sensitivity was 0.5 and specificity 93, resulting in a C-statistic of 0.75 (95% CI 0.57-0.90). The hazard ratio for SCD was 12.4 (95% CI 1.8-88.1) (P = .01); the sensitivity and specificity were 0.5 and 0.92, and the C-statistic was 0.81 (95% CI 0.67-0.95). CONCLUSION The PREVENTION-ACHD risk score model provides greater accuracy in SCD or VT/VF risk stratification as compared with current guideline indications and identifies patients with ACHD who may benefit from preventive implantable cardioverterdefibrillator implantation
Regional Brain and Spinal Cord Volume Loss in Spinocerebellar Ataxia Type 3
Background: Given that new therapeutic options for spinocerebellar ataxias are on the horizon, there is a need for markers that reflect disease-related alterations, in particular, in the preataxic stage, in which clinical scales are lacking sensitivity. Objective: The objective of this study was to quantify regional brain volumes and upper cervical spinal cord areas in spinocerebellar ataxia type 3 in vivo across the entire time course of the disease. Methods: We applied a brain segmentation approach that included a lobular subsegmentation of the cerebellum to magnetic resonance images of 210 ataxic and 48 preataxic spinocerebellar ataxia type 3 mutation carriers and 63 healthy controls. In addition, cervical cord cross-sectional areas were determined at 2 levels. Results: The metrics of cervical spinal cord segments C3 and C2, medulla oblongata, pons, and pallidum, and the cerebellar anterior lobe were reduced in preataxic mutation carriers compared with controls. Those of cervical spinal cord segments C2 and C3, medulla oblongata, pons, midbrain, cerebellar lobules crus II and X, cerebellar white matter, and pallidum were reduced in ataxic compared with nonataxic carriers. Of all metrics studied, pontine volume showed the steepest decline across the disease course. It covaried with ataxia severity, CAG repeat length, and age. The multivariate model derived from this analysis explained 46.33% of the variance of pontine volume. Conclusion: Regional brain and spinal cord tissue loss in spinocerebellar ataxia type 3 starts before ataxia onset. Pontine volume appears to be the most promising imaging biomarker candidate for interventional trials that aim at slowing the progression of spinocerebellar ataxia type 3. © 2021 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society
Is non-sustained ventricular tachycardia a predictor of sudden death in adults with congenital heart disease?
Cardiac resynchronization therapy for the failing systemic right ventricle: A systematic review
Patients with a systemic right ventricle (SRV) are at high risk for development of heart failure early in life. An SRV is encountered in patients with congenitally corrected transposition of the great arteries (CCTGA) or dextro-transposition of the great arteries (DTGA) with previous atrial switch repair (Mustard or Senning procedure). Progressive heart failure is one of the leading cause of mortality in these patients. Therefore, cardiac resynchronization therapy (CRT) has gained increasing momentum for use in this challenging congenital heart disease (CHD) population. However, current guidelines differ in recommendations for CRT in patients with an SRV as evidence supporting CRT has thus far only been described in case reports and retrospectively in relatively small study populations. In fact, the European Society of Cardiology Guideline for the management of grown-up congenital heart disease consider CRT to be ‘experimental’ in this population. This systematic review critically summarizes current literature on CRT in SRV patients and provides future perspectives for further research in this challenging and growing CHD population
Physical activity interventions for people with congenital heart disease (protocol)
This is the final version. Available from Cochrane Collaboration via the DOI in this recordThere is another record in ORE for this publication: http://hdl.handle.net/10871/39378This is a protocol for a Cochrane Review (Intervention). The objectives are as follows: To assess the effectiveness and safety of physical activity promotion and exercise training interventions in individuals with congenital heart disease
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