Stabilizing switching signals: a transition from point-wise to asymptotic conditions

Characterization of classes of switching signals that ensure stability of switched systems occupies a significant portion of the switched systems literature. This article collects a multitude of stabilizing switching signals under an umbrella framework. We achieve this in two steps: Firstly, given a family of systems, possibly containing unstable dynamics, we propose a new and general class of stabilizing switching signals. Secondly, we demonstrate that prior results based on both point-wise and asymptotic characterizations follow our result. This is the first attempt in the switched systems literature where these switching signals are unified under one banner.Comment: 7 page

A graph theoretic approach to input-to-state stability of switched systems

This article deals with input-to-state stability (ISS) of discrete-time switched systems. Given a family of nonlinear systems with exogenous inputs, we present a class of switching signals under which the resulting switched system is ISS. We allow non-ISS systems in the family and our analysis involves graph-theoretic arguments. A weighted digraph is associated to the switched system, and a switching signal is expressed as an infinite walk on this digraph, both in a natural way. Our class of stabilizing switching signals (infinite walks) is periodic in nature and affords simple algorithmic construction.Comment: 14 pages, 1 figur

Technological innovations for societal change : Arsenic mitigation technologies for safe drinking water in rural Bangladesh

Although there has been considerable progress in providing pathogen-safe drinking water, including in the developing world, contamination of groundwater by naturally occurring arsenic is now recognised as a severe environmental and health disaster. This is a serious challenge in rural Bangladesh as well. The provisioning of safe drinking water through development of arsenic mitigation technologies remains a socially and technically complex and expensive task. With an effort of two decades, two categories of arsenic mitigation technologies have been developed and introduced in Bangladesh: first, arsenic removal technologies that purify arsenic-contaminated shallow tube well water and alternatives to the shallow-tube well. However, no single arsenic mitigation technology has been widely taken up, particularly one that is suitable for all affected areas. Besides, a wide range of arsenic mitigation technologies and/or safe drinking water options face challenges of social acceptability and widespread dissemination. This generates a complex socio-technical challenge of how to provide safe drinking water to the rural population of Bangladesh, requiring input from both technical and social sciences. This thesis analyses socio-technical changes in the safe drinking water regime in rural Bangladesh, following the discovery of arsenic contamination of shallow tube well drinking water. The overarching research objective is to understand the factors shaping the success and failure of socio-technical changes to the safe drinking water sector in rural Bangladesh in the post-arsenic contamination phase. The four sub-research questions to address this research objective are: How do users understand social acceptability of three diverse arsenic mitigation technologies (deep tube well, improved dug well and Sono filter) in use in rural Bangladesh?How and why does a technological innovation (the deep tube well) deployed to provide safe drinking water become dominant in the context of arsenic contamination?Why did the promising take-off of the household arsenic removal Sono filter technology stagnate and fail to establish itself as a niche technology?How do novel experimental technologies (such as the Sub-Surface Arsenic Removal) function as emerging socio-technical experiments in rural Bangladesh, and (how) can they re-stabilize the safe drinking water regime? Using a case study methodology and qualitative methods of data generation such as surveys, semi-structured interviews, focus group discussions and primary document analysis, this thesis addresses the research questions in three steps (Chapters 2-4). Chapter 2 undertakes a user-oriented analysis of social acceptability of arsenic safe technologies (Sono filter, Deep tube well and Improved dug well) in rural Bangladesh. The chapter draws on focus groups and semi-structured interviews with technology users in six villages across three districts to analyze how users assess the social acceptability of specific arsenic safe technologies. The findings highlight that factors such as availability, affordability and compatibility with existing water use practices, as understood by users, are key to securing their acceptance of a specific arsenic safe option. In concluding, this chapter points to a future research agenda in analyzing user-oriented social acceptability of arsenic safe technologies in developing country contexts. Chapter 3 explains why and how the deep tube well as a safe drinking water technology has become dominant in mitigating the arsenic crisis in rural Bangladesh. This chapter applies insights from the Multi-Level Perspective on transitions in explaining changes to the socio-technical safe drinking water regime in rural Bangladesh. Data about seven dimensions of regime change was gathered from key actors, through in-depth interviews, focus groups sessions, a survey and a workshop. The findings reveal that with the introduction of deep tube well as an arsenic mitigation technology, changes in the seven dimensions helped to transform the existing safe drinking water regime in order to re-stabilize it. Technological attributes, symbolic meaning, industry structures, and techno-scientific knowledge supported an evolving dominance of the deep tube well. Besides, user practices as well as related infrastructures adapted to the use of deep tube wells, and new policies stimulated its application. The analysis in this chapter reveals that the dimensions of technological change in the existing regime are consistent with the features of incremental innovation. Chapter 4 explores how arsenic contamination of shallow hand pump tube well drinking water in Bangladesh has created opportunities for radical innovations to emerge. One such innovation is the household Sono filter designed to remove arsenic from water supplies. Applying a strategic niche management approach, and based on interviews, focus groups and a workshop, this chapter explained the Sono filter’s failure to establish itself as a successful niche technology. Three explanatory factors are identified: lack of a strong social network (of technology producers, donors, users, and government actors) around it; diverging expectations regarding its potential to be a long-term solution; and lack of second order learning amongst key actors. This chapter also highlights how the overwhelming dependence on externally funded arsenic mitigation projects deters successful niche formation of radical innovations in the context of the developing world. Chapter 5 analyzes experiments in rural Bangladesh with a recent arsenic mitigation innovation, so-called Subsurface Arsenic Removal (SAR), a technique designed to secure in-situ removal of naturally occurring arsenic in groundwater. This new technology was deployed on an experimental basis in two sites in rural Bangladesh. This chapter assesses whether and to what extent these first field experiments with SAR can be conceptualized as “socio-technical experiments” designed to incubate and improve radical technological innovations by serving as ‘living lab”, “window” and/or “agent of change”. As per writings in transition theory, an experiment functions as a living lab if it permits testing, learning and improving upon a technological innovation. It functions as a window if it is able to facilitate communication and conversation by raising actors’ interest and enrolling new actors. It functions as an agent of change if it can successfully stimulate changes in potential users’ practices and behaviours. Through studying two SAR experiments, this chapter shows that this novel technology served as a living lab and window, but not (yet) as agent of change, partly because integrating social considerations (such as community buy-in, appropriate site selection and post-installation support) into SAR prototype design during field experimentation proved very difficult. A key obstacle was that the technical efficacy of the technology remained a primary concern during experimentation, and it was unsafe to make water deriving from experimental SAR units available to users. The technology thus remained an abstract idea and provided unable to stimulate behavioral changes amongst users. Overall this thesis has shown that technological innovations that are seen as more socially acceptable by users acquire dominance in a re-stabilized socio-technical regime (as is the case with the deep tube well technology). Furthermore, radical technological innovations, such as household arsenic removal filters, which are still at the niche (or pre-niche) experimental stage often struggle to establish themselves and scale up, with one reason being the lack of prospects to secure user social acceptability at these early stages. The findings of the thesis also shed light on the applicability in developing country contexts of certain concepts in transition theory, including strategic niche management of technological innovations, and the multilevel perspective shaping socio-technical transformations. One key finding is that niche formation for radical innovations cannot succeed in contexts where a hybrid set of actors involved in a socio-technical regime prioritize and promote incremental innovations. This thesis thus highlights the need to focus attention on what can be referred to as “pre-niche” activities in experimenting with radical technologies, including at the incubation phase. This can help to shed light on conditions under which real world experiments with radical innovations can serve as agents of change to facilitate sustainable uptake of arsenic safe technologies, particularly in rural developing country contexts. The thesis findings nonetheless reinforce the importance of incremental innovations in mitigating the arsenic contamination challenge in rural Bangladesh, also because of the limitations associated with dependence on external funding for experimenting with more radical innovations. These general findings have implications for the successful implementation of arsenic mitigation policies, and sustainable experimentation and uptake of safe drinking water innovations in rural Bangladesh, even as they provide input into the relevance of a transition theory lens into socio-technical transformations in a developing country context.</p

Efficacy and safety during endoscopic retrograde cholangiopancreatography (ERCP) under total intravenous anesthesia – propofol alone versus propofol supplemented with dexketa, a comparative study in medical college, Kolkata

Background: Endoscopic retrograde cholangiopancreatography (ERCP) is an invasive procedure and, hence, is distressing for awake patients, requiring an adequate level of anesthesia. Recent advancements have encouraged the use of monitored anesthesia care, that allows the patient to tolerate unpleasant experiences during procedures while maintaining cardio-respiratory function. Usually, propofol-based anesthesia is given in ERCP. The main aim of this study is to compare the effect of propofol alone and propofol with ketamine and dexmedetomidine on the hemodynamics during ERCP, recovery profile, and side effects (if any). Aims and Objectives: (1) To compare efficacy in terms of hemodynamic stability and desaturation events. (2) Recovery and quality of recovery. (3) Pain score. (4) Incidence of post-operative nausea and vomiting. Materials and Methods: This is a comparative double-blinded study. Adult patients from the age group of 18–70 years belonging to the American Society of Anesthesiologists (ASA-I) and ASA-II who had undergone ERCP under total intravenous anesthesia were taken and randomly assigned to either of the two groups. Both groups received 0.01 mg/kg glycopyrrolate, 0.1 mg/kg ondansetron, 0.05 mg/kg midazolam, 50 mcg fentanyl, and 40 mg hyoscine. Group A patients received 30 mg propofol as a bolus dose and then repeated according to requirements. Group B patients received 0.5 mcg/kg dexmedetomidine as a loading dose and 0.3 mcg/kg/h as a maintenance infusion dose. 30 mg propofol was given before negotiating scope and then 1 mL (1:1) mixture of propofol and ketamine was repeated according to requirements. Total propofol consumption, hemodynamics, quality of recovery, and side effects (if any) were recorded at regular intervals. Results: The study showed significant cases in Group A had episodes of hypotension and apneic events, whereas there were very few hemodynamic instability and almost no apneic events in Group B patients. The requirement of propofol was much higher in Group A patients. Conclusion: Dexmedetomidine when used along with propofol and ketamine in ERCP patients reduced the dose requirement of propofol and maintained hemodynamic stability without causing any apneic events

Source of Previous Treatment for Re-Treatment TB Cases Registered under the National TB Control Programme, India, 2010

BACKGROUND: In 2009, nearly half (289,756) of global re-treatment TB notifications are from India; no nationally-representative data on the source of previous treatment was available to inform strategies for improvement of initial TB treatment outcome. OBJECTIVES: To assess the source of previous treatment for re-treatment TB patients registered under India's Revised National TB control Programme (RNTCP). METHODOLOGY: A nationally-representative cross sectional study was conducted in a sample of 36 randomly-selected districts. All consecutively registered retreatment TB patients during a defined 15-day period in these 36 districts were contacted and the information on the source of previous treatment sought. RESULTS: Data was collected from all 1712 retreatment TB patients registered in the identified districts during the study period. The data includes information on 595 'relapse' cases, 105 'failure' cases, 437 'treatment after default (TAD)' cases and 575 're-treatment others' cases. The source of most recent previous anti-tuberculosis therapy for 754 [44% (95% CI, 38.2%-49.9%)] of the re-treatment TB patients was from providers outside the TB control programme. A higher proportion of patients registered as TAD (64%) and 'retreatment others' (59%) were likely to be treated outside the National Programme, when compared to the proportion among 'relapse' (22%) or 'failure' (6%). Extrapolated to national registration, of the 292,972 re-treatment registrations in 2010, 128,907 patients would have been most recently treated outside the national programme. CONCLUSIONS: Nearly half of the re-treatment cases registered with the national programme were most recently treated outside the programme setting. Enhanced efforts towards extending treatment support and supervision to patients treated by private sector treatment providers are urgently required to improve the quality of treatment and reduce the numbers of patients with recurrent disease. In addition, reasons for the large number of recurrent TB cases from those already treated by the national programme require urgent detailed investigation

Production of He-4 and (4) in Pb-Pb collisions at root(NN)-N-S=2.76 TeV at the LHC

Results on the production of He-4 and (4) nuclei in Pb-Pb collisions at root(NN)-N-S = 2.76 TeV in the rapidity range vertical bar y vertical bar <1, using the ALICE detector, are presented in this paper. The rapidity densities corresponding to 0-10% central events are found to be dN/dy4(He) = (0.8 +/- 0.4 (stat) +/- 0.3 (syst)) x 10(-6) and dN/dy4 = (1.1 +/- 0.4 (stat) +/- 0.2 (syst)) x 10(-6), respectively. This is in agreement with the statistical thermal model expectation assuming the same chemical freeze-out temperature (T-chem = 156 MeV) as for light hadrons. The measured ratio of (4)/He-4 is 1.4 +/- 0.8 (stat) +/- 0.5 (syst). (C) 2018 Published by Elsevier B.V.Peer reviewe