186 research outputs found
Prevalence, comorbidities and mediators of childhood anxiety disorders in urban Turkey: a national representative epidemiological study
Get PDF© 2022, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany.Purpose: The aim of this study is to evaluate the prevalence of anxiety disorders, its correlation with sociodemographic characteristics, its comorbidities with other psychiatric disorders and its predictors in school-aged children. Methods: This study is part of a representative, multi-centered national study that is planned by the Turkish Association of Child and Adolescent Mental Health to evaluate the prevalence of psychopathology among elementary school students in Turkey between the years 2014–2015. Children are screened via Kiddie Schedule for Affective Disorders and Schizophrenia for School Age Children Present and Lifetime Version. Impairment is assessed by a 3-point Likert type scale independently by the parent and the teacher. The final sample included 5842 children with the mean age of 8.7 years. Results: The prevalence of any anxiety disorder without considering impairment is 16.7% and considering impairment is 5.2% in children according to our study. We found significant differences for comorbid Attention Deficit Hyperactivity Disorder, Disruptive Behavior Disorder, Mood Disorders, Tic Disorders, Obsessive Compulsive Disorder, Enuresis Nocturna, Encopresis, and Intellectual Disability. Having a history of paternal physical disorder, living in the regions of Marmara, Mediterranean and Black Sea were found to be the main predictors of having childhood anxiety disorders according to the logistic regression analysis. Conclusion: Better understanding of childhood anxiety disorders, comorbid conditions and predictors will result in earlier diagnosis and more appropriate treatment
Occupational radiation exposure among medical personnel in university and general hospitals in Japan
Get PDFNagasaki University (長崎大学)博士(医学)Objective: This study aimed to compare the occupational radiation exposure of medical workers between general hospitals and university hospitals. Methods: Radiation exposure data from three hospitals in Hiroshima city, including one university hospital and two general hospitals, were collected using personal dosimeters. Monthly radiation doses were analyzed, and the annual sum of radiation exposure dose was calculated for 538 subjects in general hospitals and 1224 subjects in the university hospital. To assess the impact of locality, additional data from Nagasaki University Hospital and Fukushima Medical University Hospital were included for comparative analysis. Professional affiliations, such as doctors, nurses, and radiological technologists, were considered in the evaluation. Results: The study revealed slight but significant differences in radiation doses between general and university hospitals. In general hospitals, except for radiological technologists, a slightly higher radiation dose was observed compared to university hospitals. Despite the annual increase in the use of medical radiation, the majority of hospital workers in both settings adhered to safety guidelines, with occupational radiation exposure remaining below the limit of detection (LOD). Workers who involved in fluoroscopic procedure, whether at university or general hospitals, had higher radiation doses than those who did not. Conclusion: The study's primary conclusion is that workers in general hospitals experience a slight but significantly higher radiation dose and a lower percentage below the LOD compared to university hospitals. The observed difference is attributed to the greater workload at general hospitals than at university hospitals, and also may be due to the different nature of university hospital and general hospital. University hospitals, characterized by greater academic orientation, tend to benefit from comprehensive support systems, specialized expertise, and advanced technology, leading to more structured and regulated radiation control. These findings provide a basis for targeted interventions, improved safety protocols.長崎大学学位論文 学位記番号:博(医歯薬)甲第1677号 学位授与年月日:令和7年3月5日Author: Arman Nessipkhan, Naoki Matsuda, Noboru Takamura, Noboru Oriuchi, Hiroshi Ito, Masao Kiguchi, Kiyoto Nishihara, Takayuki Tamaru, Kazuo Awai, Takashi KudoCitation: Japanese Journal of Radiology, 42, pp.1067-1079; 2024Nagasaki University (長崎大学), 博士(医学) (2025-03-05)doctoral thesi
Identifying Blockages and Unblocking Strategy for Digital Trade Infrastructures Innovation Process
No full textRole of digital infrastructures to improve data exchange on trade lanes becomes more critical as complex border procedures contribute to inefficiency of the international supply chain. However, digital infrastructures innovation in international trade (DTI) has not reached the implementation phase. We are interested to analyse digital trade infrastructures innovation process based on its innovation system. The dynamic of innovation system influences the speed of innovation process. We argue that the blockages and unblocking strategy of DTI innovation process can be clearly identified if the innovation system is examined by looking at two levels of analysis, which are structural, related to changes in system’s structure (e.g., actors, networks, governance) and functional, related to the ability of such system to perform certain functions towards achieving its objectives. To the knowledge of the author, there is no theoretical lens which discusses activities and events happened in DTI innovation system to a detailed breakdown of its structural or functional changes. Mainly the existing studies only focus on using the innovation system analysis as the analytical tool for directing innovation policy and neglect the collective action process that is very relevant with characteristics of DI development. Therefore, the research objective is to create and apply a conceptual framework, to identify the unblocking strategy for digital trade infrastructures innovation process by looking at structural and functional analysis of the innovation system. We develop conceptual framework namely Structural-Functional Analysis Framework, based on the desk research. We evaluate the framework through a longitudinal IT innovation case study on EU funded project. Documents analysis and interviews are employed as data collection methods. From the framework evaluation, this study reports that the combination of analyses concerning structural changes and functional performance of an innovation system is capable to provide richer explanation on issues that limit an innovation system to further develop the DI innovation, a strategy that can be done to mobilise the innovation process, and the DI innovation process itself.<br/
The effect of ectopic expression of pine glutamine synthetase (GS1a) on water use efficiency in transgenic poplar
No full textGlutamine synthetase (GS) is a key factor in the assimilation of nitrogen in plants. Hybrid poplar plants (Populus tremula X P. alba, INRA 717-1-B4) ectopically expressing pine GS display increased growth rates, increased nitrogen use efficiency, and resistance to drought. In order to assess mechanisms associated with observed drought tolerance of GS poplars, we studied the ability of the GS poplars to perform photosynthesis under control and water-limiting conditions, as well as their nitrogen and carbon isotope contents. Included in this study were carboxylation efficiency, maximum assimilation rate, quantum yield of photosynthesis, maximum electron transport rate, dark respiration, triose phosphate utilization, light compensation point, intrinsic water use efficiency, stomatal conductance, and nitrogen-use efficiency. Rooted cuttings (12-18 months) were grown in a growth chamber (24o C; 16 hour photoperiod; approx. 330 μmol m-2 s-1). Well-watered conditions were defined as a soil moisture value of over 0.40 m3∙m-3, and drought conditions were defined as having a value of less than 0.20 m3∙m-3. The results showed significant differences between the GS transgenic and wild type. Under drought and control conditions, GS poplars showed carboxylation efficiencies similar to wild type grown under well-watered and drought conditions. Photosynthetic capacities were not different regardless of condition or genotype. However, the GS poplars showed lower water use efficiency when compared to the wild type, but higher nitrogen use efficiency. These data suggest that, compared to the wild type, GS poplars display a tradeoff between water and nitrogen use efficiency and are characterized by slightly enhanced photosynthesis, even during drought stress.M.S.Includes bibliographical referencesIncludes vitaby Arman Yalci
Mathematical Model of Synchronous Motors for Static Characteristics Power Loss
No full textAbstractThis article analyses the mathematical model of synchronous motors and its application to build statistic power characteristics. The paper presents the static characteristics of active power losses, analysing which the author comes to certain conclusions regarding the minimization of losses in the synchronous motor
Continuous-Time Accelerated Methods via a Hybrid Control Lens
No full textTreating optimization methods as dynamical systems can be traced back centuries ago in order to comprehend the notions and behaviors of optimization methods. Lately, this mindset has become the driving force to design new optimization methods. Inspired by the recent dynamical system viewpoint of Nesterov's fast method, we propose two classes of fast methods, formulated as hybrid control systems, to obtain prespecified exponential convergence rate. Alternative to the existing fast methods, which are parametric-in-time second-order differential equations, we dynamically synthesize feedback controls in a state-dependent manner. Namely, in the first class, the damping term is viewed as the control input, while in the second class the amplitude with which the gradient of the objective function impacts the dynamics serves as the controller. The objective function requires to satisfy the so-called Polyak-Łojasiewicz inequality, which effectively implies no local optima and a certain gradient-domination property. Moreover, we establish that both hybrid structures possess Zeno-free solution trajectories. We finally provide a mechanism to determine the discretization step size to attain an exponential convergence rate. Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Team Tamas KeviczkyTeam Bart De Schutte
Abstracted models for scheduling of event-triggered control data traffic
No full textEvent-Triggered control (ETC) implementations have been proposed to overcome the inefficiencies of periodic (time-triggered) controller designs, namely the over-exploitation of the computing and communication infrastructure. However, the potential of aperiodic Event-Triggered techniques to reuse the freed bandwidth, and to reduce energy consumption on wireless settings, has not yet been truly reached. The main limitation to fully exploit ETC’s great traffic reductions lies on the difficulty to predict the occurrence of controller updates, forcing the use of conservative scheduling approaches in practice. Having a model of the timing behaviour of ETC is of paramount importance to enable the construction of model-based schedulers for such systems. Furthermore, on wireless control systems these schedulers allow to tightly schedule listening times, thus reducing energy consumption. In this chapter we describe an approach to model ETC traffic employing ideas from the symbolic abstractions literature. The resulting models of traffic are timed-automata. We also discuss briefly how these models can be employed to automatically synthesize schedulers.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Team Tamas Keviczk
Applications of trajectory-based analysis in optimization and control
No full textThe synergy between optimization and control is a long standing tradition. In fact, this synergy is becoming more and more apparent because of the multi-disciplinary character of the most pressing, current engineering problems along with constant developments of these two fields. Historically, optimization methods have helped the control community to achieve their design goals formalized in some sort of objective function. On the other hand, control theory has provided a setting to interpret complicated aspects of optimization algorithms. In this thesis, we address three problem instances that lie on the boundary of optimization and control. We employ tools from one field to address a problem in the other field. Fundamentally, our proposed methods share a similar character: their analysis techniques are trajectory-based. In simple words, our proposed methods exploit the trajectories generated by the dynamics that represent each problem instance. The first problem focuses on a 2nd-order, damped differential equation (ODE). This ODE along with its numerous variations have been used to develop or analyze various optimization algorithms, known as fast methods. As an alternative to the existing methods, we first amend the underling ODE with two types of state-dependent inputs, and then extend the resulting controlled dynamics to two hybrid control systems. Employing a trajectory-based analysis, both control laws are constructed to guarantee exponential convergence in a suboptimality measure. To show that the trajectories generated by each hybrid control system are well-posed, we demonstrate Zeno-freeness of solution trajectories in both cases. Furthermore, we propose a mechanism to determine a time-discretization step-size such that the resulting discrete-time hybrid control systems are exponentially stable. Event-based implementation of control laws have received a lot of attention during the past decade. The reason for this interest is the hope to reduce the conservatism involved in the traditional periodic implementation. In the second problem of this thesis, we introduce an event-based sampling policy for a constraint-tightening, robust model predictive control (RMPC) method. The triggering mechanism is a sequence of hyper-rectangles constructed around the optimal state trajectories. In particular, the triggering mechanism's nature makes the proposed approach a suitable choice for plants without a centralized sensory node. A key feature of the proposed method is its complete decoupling from the RMPC method's parameters, facilitating a meaningful comparison between the periodic and aperiodic implementation policies. Furthermore, we provide two types of convex formulations to design the triggering mechanism.The last problem we focus on in this thesis is also related to the event-based implementation of a control law. However, the main aim here is to propose an entity that can be utilized by a real-time engineer to schedule tasks in a networked structure. A common entity provided in the literature related to event-triggering approaches is the minimal inter-execution time (to show the avoidance of a Zeno behavior in the closed-loop system). Nonetheless, such a quantity is extremely conservative when used for scheduling purposes. In this problem, we consider an -based triggering mechanism introduced in the literature and propose a framework to construct a timed safety automaton that can capture the triggering instants generated by this mechanism. In our analysis, we borrow some tools from stability analysis of delayed systems along with reachability analysis to construct the desired timed safety automaton.Team Tamas Keviczk
Robust Model Predictive Control with Aperiodic Actuation: Employing a Decentralized Triggering Mechanism
No full textIn this thesis, a control design problem, in which communication between different elements of the control system takes place through a shared (possibly wireless) channel, is considered. With the implementation of the proposed approach, the use of limited resources such as network bandwidth and battery life may be reduced.The proposal consists of a robust model predictive control (MPC) approach, that is only executed at instants at which a decentralized triggering mechanism triggers. As long as no triggering occurs, inputs that have been computed at the previous MPC update are used. The triggering mechanism uses the trajectories from the MPC to calculate bounds on the error between each actual state and predicted state, for all instants up to the horizon. When all individual errors are inside their respective bounds at some instant, violation at the next instant still results in an MPC problem that is (1) guaranteed to have a feasible solution and (2) for which an upper bound for the objective function value is given that is lower than the value at the previous instant. These two properties result in stability of the closed loop system. Simulation results are given to demonstrate the effectiveness of the proposed approach. Compared to approaches that solve similar problems that can be found in literature, the proposed approach differs in the need for weaker assumptions and/or in the maximization of the bounds on the error signal. This is made possible by letting the triggering mechanism depend on the sequences that are generated by the MPC at the last update instant, as well as the measured state.Mechanical Engineering | Systems and Contro
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