Controllability and controller-observer design for a class of linear time-varying systems

“The final publication is available at Springer via http://dx.doi.org/10.1007/s10852-012-9212-6"In this paper a class of linear time-varying control systems is considered. The time variation consists of a scalar time-varying coefficient multiplying the state matrix of an otherwise time-invariant system. Under very weak assumptions of this coefficient, we show that the controllability can be assessed by an algebraic rank condition, Kalman canonical decomposition is possible, and we give a method for designing a linear state-feedback controller and Luenberger observer

Quality of life and visual function in Nigeria: findings from the National Survey of Blindness and Visual Impairment

Aims To assess associations of visual function (VF) and quality of life (QOL) by visual acuity (VA), causes of blindness and types of cataract procedures in Nigeria. Methods Multi-stage stratified cluster random sampling was used to identify a nationally representative sample of persons aged >= 40 years. VF/QOL questionnaires were administered to participants with VA = 6/12. Results VF/QOL questionnaires were administered to 2076 participants. Spearman's rank correlation showed a strong correlation between decreasing VA and VF/QOL scores (p< 0.0001) with greatest impact on social (p< 0.0001) and mobility-related activities (p< 0.0001). People who were blind due to glaucoma had lower VF and QOL scores than those who were blind due to cataract. Mean VF and QOL scores were lower after couching compared with conventional cataract surgery (mean VF score=51.0 vs 63.0 and mean QOL score=71.3 vs 79.3). Finally, VF and QOL scores were lower among populations with specific characteristics. Conclusions Populations with the following characteristics should be targeted to improve VF and QOL: people who are blind, older people, women, manual labourers, people living in rural areas, those living in the northern geopolitical zones, those practising Islamic and Traditionalism faith, those not currently married and those who have undergone couching

Identifying risk factors that contribute to acute mountain sickness

Background. Acute mountain sickness (AMS) is an ever-increasing burden on the health sector. With reported incidences of greater than 50%, coupled with the fact that recreational activities at high altitude are gaining increasing popularity, more persons are developing AMS. Physicians are therefore increasingly faced with the task of managing and preventing AMS.Objectives. The pathophysiology of AMS is poorly understood, with little understanding of risk factors for the development of AMS. This research aimed to identify epidemiological and physiological risk factors for development of AMS.Methods. This study is a questionnaire-based study conducted in London and at Everest Base Camp, in which 116 lowlanders were invited to participate and fill in a questionnaire to identify potential risk factors in their history that may have contributed to development of or protection against AMS.Results. A total of 89 lowlanders enrolled in the study. Thirty-seven of the participants had AMS at  Everest Base Camp, giving a prevalence of 42%. Of the demographic variables, only weight and body  mass index (BMI) were statistically significantly associated with AMS, with those who weighed less or had a lower BMI more likely to get AMS. Previous high-altitude experience was also associated with AMS, with those who had such experience less likely to get AMS.Conclusion. Predicting AMS and furthering our understanding of the pathophysiology of AMS will be of tremendous benefit. Further research is needed in this regard

Starting-up unregistered and firm performance in Turkey

© 2016 The Author(s) Recent years have seen a questioning of the negative representation of informal sector entrepreneurship and an emergent view that it may offer significant benefits. This paper advances this rethinking by evaluating the relationship between business registration and future firm performance. Until now, the assumption has been that starting-up unregistered is linked to weaker firm performance. Using World Bank Enterprise Survey data on 2494 formal enterprises in Turkey, and controlling for other determinants of firm performance as well as the endogeneity of the registration decision, the finding is that formal enterprises that started-up unregistered and spent longer unregistered have significantly higher subsequent annual sales and productivity growth rates compared with those registered from the outset. This is argued to be because in such weak institutional environments, the advantages of registering from the outset are outweighed by the benefits of deferring business registration and the low risks of detection and punishment. The resultant implication is that there is a need to shift away from the conventional eradication approach based on the negative depiction of informal entrepreneurship as poorly performing, and towards a more facilitating approach that improves the benefits of business registration and tackles the systemic formal institutional deficiencies that lead entrepreneurs to decide to delay the registration of their ventures

Psychological and physiological effects of compassionate mind training: A pilot randomised controlled study

The development of the compassionate self, associated with practices such as slow and deeper breathing, compassionate voice tones and facial expressions and compassionate focusing is central to Compassion Focused Therapy. This study explores the impact of a two-week Compassionate Mind Training (CMT) program on emotional, self-evaluative and psychopathology measures and on heart rate variability (HRV). Participants (general population and college students) were randomly assigned to one of two conditions: CMT (n=56) and Wait-List Control (n=37). Participants in the CMTcondition were instructed to practice CMT exercises during two weeks. Self-report measures of compassion, positive affect, fears of compassion, self-criticism, shame, depression, anxiety and stress, and HRV were collected at pre and post intervention in both conditions. Compared to the control group, the experimental group showed significant increases in positive emotions, associated with feeling relaxed and also safe and content, but not activated; and in self-compassion, compassion for others and compassion from others. There were significant reductions in shame, self-criticism, fears of compassion, and stress. Only the experimental group reported significant improvement in HRV. Developing awareness of the evolved nature and inherent difficulties of our minds allied with practicing CMT exercises has beneficial effects on participants' psychological and physiological well-being.N/

TAXON version 1.1: A simple way to generate uniform and fractionally weighted three-item matrices from various kinds of biological data

An open-access program allowing three-item statement matrices to be generated from data such as molecular sequences does not exist so far. The recently developed LisBeth package (ver. 1.0) allows representing hypotheses of homology among taxa or areas directly as rooted trees or as hierarchies; however, this is not a standard matrix-based platform. Here we present "TAXON version 1.1" (TAXON), a program designed for building three-item statement-matrices from binary, additive (ordered) and non-additive (unordered) multistate characters, with both fractional and uniform weighting of the resulted statements.Comment: 4 pages, 1 figure, 1 Supplement, 3 Supplemental example

Prospective memory functioning among ecstasy/polydrug users: evidence from the Cambridge Prospective Memory Test (CAMPROMPT)

Rationale: Prospective memory (PM) deficits in recreational drug users have been documented in recent years. However, the assessment of PM has largely been restricted to self-reported measures that fail to capture the distinction between event-based and time-based PM. The aim of the present study is to address this limitation. Objectives: Extending our previous research, we augmented the range laboratory measures of PM by employing the CAMPROMPT test battery to investigate the impact of illicit drug use on prospective remembering in a sample of cannabis only, ecstasy/polydrug and non-users of illicit drugs, separating event and time-based PM performance. We also administered measures of executive function and retrospective memory in order to establish whether ecstasy/polydrug deficits in PM were mediated by group differences in these processes. Results: Ecstasy/polydrug users performed significantly worse on both event and time-based prospective memory tasks in comparison to both cannabis only and non-user groups. Furthermore, it was found that across the whole sample, better retrospective memory and executive functioning was associated with superior PM performance. Nevertheless, this association did not mediate the drug-related effects that were observed. Consistent with our previous study, recreational use of cocaine was linked to PM deficits. Conclusions: PM deficits have again been found among ecstasy/polydrug users, which appear to be unrelated to group differences in executive function and retrospective memory. However, the possibility that these are attributable to cocaine use cannot be excluded

Temporal trends and socioeconomic differences in acute respiratory infection hospitalisations in children: an intercountry comparison of birth cohort studies in Western Australia, England and Scotland

OBJECTIVES: Acute respiratory infections (ARIs) are a global cause of childhood morbidity. We compared temporal trends and socioeconomic disparities for ARI hospitalisations in young children across Western Australia, England and Scotland. DESIGN: Retrospective population-based cohort studies using linked birth, death and hospitalisation data. SETTING AND PARTICIPANTS: Population birth cohorts spanning 2000-2012 (Western Australia and Scotland) and 2003-2012 (England). OUTCOME MEASURES: ARI hospitalisations in infants (<12 months) and children (1-4 years) were identified through International Classification of Diseases, 10th edition diagnosis codes. We calculated admission rates per 1000 child-years by diagnosis and jurisdiction-specific socioeconomic deprivation and used negative binomial regression to assess temporal trends. RESULTS: The overall infant ARI admission rate was 44.3/1000 child-years in Western Australia, 40.7/1000 in Scotland and 40.1/1000 in England. Equivalent rates in children aged 1-4 years were 9.0, 7.6 and 7.6. Bronchiolitis was the most common diagnosis. Compared with the least socioeconomically deprived, those most deprived had higher ARI hospitalisation risk (incidence rate ratio 3.9 (95% CI 3.5 to 4.2) for Western Australia; 1.9 (1.7 to 2.1) for England; 1.3 (1.1 to 1.4) for Scotland. ARI admissions in infants were stable in Western Australia but increased annually in England (5%) and Scotland (3%) after adjusting for non-ARI admissions, sex and deprivation. CONCLUSIONS: Admissions for ARI were higher in Western Australia and displayed greater socioeconomic disparities than England and Scotland, where ARI rates are increasing. Prevention programmes focusing on disadvantaged populations in all three countries are likely to translate into real improvements in the burden of ARI in children

Cluster-randomized trial of a web-assisted tobacco quality improvement intervention of subsequent patient tobacco product use: A national dental PBRN study

ABSTRACT: BACKGROUND: Brief clinician delivered advice helps in tobacco cessation efforts. This study assessed the impact of our intervention on instances of advice given to dental patients during visits on tobacco use quit rates 6 months after the intervention. METHODS: The intervention was cluster randomized trial at the dental practice level. Intervention dental practices were provided a longitudinal technology-assisted intervention, oralcancerprevention.org that included a series of interactive educational cases and motivational email cues to remind dental provides to complete guideline-concordant brief behavioral counseling at the point of care. In all dental practices, exit cards were given to the first 100 consecutive patients, in which tobacco users provided contact information for a six month follow-up telephone survey. RESULTS: A total of 564 tobacco using dental patients completed a six month follow-up survey. Among intervention patients, 55% reported receiving advice to quit tobacco, and 39% of control practice patients reported receiving advice to quit tobacco (p \u3c 0.01). Six-month tobacco use quit rates were not significantly between the Intervention (9%) and Control (13%) groups, (p = 0.088). CONCLUSION: Although we increased rates of cessation advice delivered in dental practices, this study shows no evidence that brief advice by dentist\u27s increases long-term abstinence in smokers.Trial registration: ClinicalTrials.gov NCT00627185