An EM-based identification algorithm for a class of hybrid systems with application to power electronics

In this paper we present an identification algorithm for a class of continuous-time hybrid systems. In such systems, both continuous-time and discrete-time dynamics are involved. We apply the expectation-maximisation algorithm to obtain the maximum likelihood estimate of the parameters of a discrete-time model expressed in incremental form. The main advantage of this approach is that the continuous-time parameters can directly be recovered. The technique is particularly well suited to fast-sampling rates. As an application, we focus on a standard identification problem in power electronics. In this field, our proposed algorithm is of importance since accurate modelling of power converters is required in high- performance applications and for fault diagnosis. As an illustrative example, and to verify the performance of our proposed algorithm, we apply our results to a flying capacitor multicell converter. © 2014 © 2014 Taylor & Francis

A pilot study comparing the metabolic profiles of elite-level athletes from different sporting disciplines

Background: The outstanding performance of an elite athlete might be associated with changes in their blood metabolic profile. The aims of this study were to compare the blood metabolic profiles between moderate- and high-power and endurance elite athletes and to identify the potential metabolic pathways underlying these differences. Methods: Metabolic profiling of serum samples from 191 elite athletes from different sports disciplines (121 high- and 70 moderate-endurance athletes, including 44 high- and 144 moderate-power athletes), who participated in national or international sports events and tested negative for doping abuse at anti-doping laboratories, was performed using non-targeted metabolomics-based mass spectroscopy combined with ultrahigh-performance liquid chromatography. Multivariate analysis was conducted using orthogonal partial least squares discriminant analysis. Differences in metabolic levels between high- and moderate-power and endurance sports were assessed by univariate linear models. Results: Out of 743 analyzed metabolites, gamma-glutamyl amino acids were significantly reduced in both high-power and high-endurance athletes compared to moderate counterparts, indicating active glutathione cycle. High-endurance athletes exhibited significant increases in the levels of several sex hormone steroids involved in testosterone and progesterone synthesis, but decreases in diacylglycerols and ecosanoids. High-power athletes had increased levels of phospholipids and xanthine metabolites compared to moderate-power counterparts. Conclusions: This pilot data provides evidence that high-power and high-endurance athletes exhibit a distinct metabolic profile that reflects steroid biosynthesis, fatty acid metabolism, oxidative stress, and energy-related metabolites. Replication studies are warranted to confirm differences in the metabolic profiles associated with athletes’ elite performance in independent data sets, aiming ultimately for deeper understanding of the underlying biochemical processes that could be utilized as biomarkers with potential therapeutic implications

Intermittent control models of human standing: similarities and differences

Two architectures of intermittent control are compared and contrasted in the context of the single inverted pendulum model often used for describing standing in humans. The architectures are similar insofar as they use periods of open-loop control punctuated by switching events when crossing a switching surface to keep the system state trajectories close to trajectories leading to equilibrium. The architectures differ in two significant ways. Firstly, in one case, the open-loop control trajectory is generated by a system-matched hold, and in the other case, the open-loop control signal is zero. Secondly, prediction is used in one case but not the other. The former difference is examined in this paper. The zero control alternative leads to periodic oscillations associated with limit cycles; whereas the system-matched control alternative gives trajectories (including homoclinic orbits) which contain the equilibrium point and do not have oscillatory behaviour. Despite this difference in behaviour, it is further shown that behaviour can appear similar when either the system is perturbed by additive noise or the system-matched trajectory generation is perturbed. The purpose of the research is to come to a common approach for understanding the theoretical properties of the two alternatives with the twin aims of choosing which provides the best explanation of current experimental data (which may not, by itself, distinguish beween the two alternatives) and suggesting future experiments to distinguish between the two alternatives

Knowledge, attitudes and practices related to avian influenza among poultry workers in Nepal: a cross sectional study

<p>Abstract</p> <p>Background</p> <p>Avian influenza is a considerable threat to global public health. Prevention and control depend on awareness and protective behaviours of the general population as well as high risk-groups. This study aims to explore the knowledge, attitudes and practices related to avian influenza among poultry workers in Nepal.</p> <p>Methods</p> <p>The study was based on a cross-sectional study design, using a structured questionnaire administered in face-to-face interviews with 96 poultry workers age 15 and above from the Rupandehi district in Nepal.</p> <p>Results</p> <p>The majority of respondents were male (80%), mean age was 35 (SD = 11.6). Nearly everybody was aware that AI cases had been detected in Nepal and that poultry workers were at risk for infection. The major sources of AI information were radio, TV and newspapers. Knowledge about preventive measures was high with regard to some behaviours (hand washing), but medium to low with regard to others (using cleaning and disinfecting procedures or protective clothing). Poultry workers who got their information from TV and newspapers and those who were more afraid of contracting AI had higher knowledge than those who did not. Being employed as compared to being an owner of a poultry farm as well as having a high level of knowledge was associated with practising more preventive behaviours. While on one hand many specific government control measures found a high degree of acceptance, a majority of study participants also thought that government control and compensation measures as a whole were insufficient.</p> <p>Conclusions</p> <p>The study provides information about knowledge and practices regarding avian influenza among poultry workers in Nepal. It highlights the importance of targeting lack of knowledge as well as structural-material barriers to successfully build preparedness for a major outbreak situation.</p

Boolean-controlled systems via receding horizon and linear programing.

We consider dynamic systems controlled by boolean signals or decisions. We show that in a number of cases, the receding horizon formulation of the control problem can be solved via linear programing by relaxing the binary constraints on the control. The idea behind our approach is conceptually easy: a feasible control can be forced by imposing that the boolean signal is set to one at least one time over the horizon. We translate this idea into constraints on the controls and analyze the polyhedron of all feasible controls. We specialize the approach to the stabilizability of switched and impulsively controlled systems

Medico-legal autopsy in postoperative hemodynamic collapse following coronary artery bypass surgery

Sudden unexpected postoperative hemodynamic collapse with a high mortality develops in 1–3% of patients undergoing coronary artery bypass surgery (CABG). The contribution of surgical graft complications to this serious condition is poorly known and their demonstration at autopsy is a challenging task. Isolated CABG was performed in 8,807 patients during 1988–1999. Of the patients, 76 (0.9%) developed sudden postoperative hemodynamic collapse resulting in subsequent emergency reopening of the median sternotomy and open cardiac massage. Further emergency reoperation could be performed in 62 (82%) whereas 14 patients died prior to reoperation and a further 21 did not survive the reoperation or died a few days later. All 35 (46%) patients who did not survive were subjected to medico-legal autopsy combined with postmortem cast angiography. By combining clinical data with autopsy and angiography data, various types of graft complications were observed in 27 (36%, 1.3 per patient) of the 76 patients with hemodynamic collapse. There were no significant differences in the frequency (33 vs. 40%) or number of complicated grafts per patient (1.2 vs. 1.4) between those who survived reoperation and who did not. Autopsy detected 25 major and minor findings not diagnosed clinically. Postmortem cast angiography visualized 2 graft twists not possible to detect by autopsy dissection only. Surgical graft complications were the most frequent single cause for sudden postoperative hemodynamic collapse in CABG patients leading to a fatal outcome in almost half of the cases. Postmortem angiography improved the accuracy of autopsy diagnostics of graft complications

The National Tumor Association Foundation (ANT): A 30 year old model of home palliative care

<p>Abstract</p> <p>Background</p> <p>Models of palliative care delivery develop within a social, cultural, and political context. This paper describes the 30-year history of the National Tumor Association (ANT), a palliative care organization founded in the Italian province of Bologna, focusing on this model of home care for palliative cancer patients and on its evaluation.</p> <p>Methods</p> <p>Data were collected from the 1986-2008 ANT archives and documents from the Emilia-Romagna Region Health Department, Italy. Outcomes of interest were changed in: number of patients served, performance status at admission (Karnofsky Performance Status score [KPS]), length of participation in the program (days of care provided), place of death (home vs. hospital/hospice), and satisfaction with care. Statistical methods included linear and quadratic regressions. A linear and a quadratic regressions were generated; the independent variable was the year, while the dependent one was the number of patients from 1986 to 2008. Two linear regressions were generated for patients died at home and in the hospital, respectively. For each regression, the R square, the unstandardized and standardized coefficients and related P-values were estimated.</p> <p>Results</p> <p>The number of patients served by ANT has increased continuously from 131 (1986) to a cumulative total of 69,336 patients (2008), at a steady rate of approximately 121 additional patients per year and with no significant gender difference. The annual number of home visits increased from 6,357 (1985) to 904,782 (2008). More ANT patients died at home than in hospice or hospital; this proportion increased from 60% (1987) to 80% (2007). The rate of growth in the number of patients dying in hospital/hospice was approximately 40 patients/year (p < 0.01), vs. approximately 177 patients/year for patients who died at home. The percentage of patients with KPS < 40 at admission decreased from 70% (2003) to 30% (2008); the percentage of patients with KPS > 40 increased. Mean days of care for patients with KPS > 40 exceeded mean days for patients with KPS < 40 (p < 0.001). Patients and caregivers reported high satisfaction with care in each year of assessment; in 2008, among 187 interviewed caregivers, 95% judged the quality of doctors' assistance, and 91% judged the quality of nurses' assistance, to be "optimal."</p> <p>Conclusions</p> <p>The ANT home care model of palliative care delivery has been well-received, with progressively growing numbers of patients served. It has resulted in a greater proportion of home deaths and in patients' accessing palliative care at an earlier point in the disease trajectory. Changes in ANT chronicle palliative care trends in general.</p

Resolving Individuals Contributing Trace Amounts of DNA to Highly Complex Mixtures Using High-Density SNP Genotyping Microarrays

We use high-density single nucleotide polymorphism (SNP) genotyping microarrays to demonstrate the ability to accurately and robustly determine whether individuals are in a complex genomic DNA mixture. We first develop a theoretical framework for detecting an individual's presence within a mixture, then show, through simulations, the limits associated with our method, and finally demonstrate experimentally the identification of the presence of genomic DNA of specific individuals within a series of highly complex genomic mixtures, including mixtures where an individual contributes less than 0.1% of the total genomic DNA. These findings shift the perceived utility of SNPs for identifying individual trace contributors within a forensics mixture, and suggest future research efforts into assessing the viability of previously sub-optimal DNA sources due to sample contamination. These findings also suggest that composite statistics across cohorts, such as allele frequency or genotype counts, do not mask identity within genome-wide association studies. The implications of these findings are discussed