Infective endocarditis

The term ‘predisposing heart condition’ is used as an indication of antimicrobial prophylaxis to prevent infective endocarditis (IE) and as a criterion for diagnosing IE according to the modified Duke criteria. Whereas the use of the term for antimicrobial prophylaxis is well defined, the criterion for diagnosing IE is not. The general objective of this thesis is to narrow the definition of a predisposing heart condition in ‘native’ valves for the diagnosis of IE. Therefore, we reviewed the literature and the evidence about specific heart conditions reported to be a risk factor for IE. In parallel, we reviewed the imaging technique available at the time these studies were published and compared the results with imaging from today’s perspectives and current definitions of a specific heart condition (i.e. valvular disease). Finally, we evaluated the knowledge and opinion of clinicians about the term predisposing heart condition. Our literature review included 207 studies, the vast majority of which were descriptive. Only a few studies investigated valve pathology as a risk factor for IE via analytical statistics. In addition, three-quarters of all included studies involved patients who presented with IE prior to the publication of the modified Duke criteria. Studies focussing on mitral valve prolapse (MVP, 116 publications), prior IE (96 publications), and bicuspid aortic valve (BAV, 78 publications) provided the most data. The odds ratio of developing IE for a patient who had previously experienced an episode of it was approximately 2.5. The mean proportion of patients with IE plus a history of previous IE was 8.3% (median 7.1%, interquartile range [IQR] 4.9%–10.2%). One study associated BAV with a higher risk of IE (hazard ratio 6.3). In 77 descriptive studies, a median of approximately 6% of patients with IE had BAV as an underlying condition. Our literature review on the evolution of imaging methods indicated, however, a considerable influence of medical progress on the diagnosis of MVP. Six analytical studies and 90 of the 110 descriptive studies included patients prior to the publication of the modified Duke criteria in 2000. For many years, MVP was diagnosed via auscultation only, and echocardiographic means for diagnosis were used in the late 90s. Therefore, both the risk of developing IE and the proportion of patients with IE and MVP as a predisposing factor could not be quantified. The literature review on mitral valve stenosis (MS, 23 publications) and pathologies involving the pulmonary valve (18 publications) and the tricuspid valve (nine publications) provided little data. These publications had inconsistent results and low proportions of patients with IE had these valve pathologies. The significance of aortic valve stenosis (AS, 46 publications), mitral valve insufficiency (MI, 41 publications), and aortic valve insufficiency (AI, 39 publications) as a predisposing heart condition was difficult to assess from today’s perspective because of the progress made in imaging methods; of these studies, 75.6%, 78.6%, and 79.5%, respectively, included patients prior to the publication of the modified Duke criteria in the year 2000. In addition, except for AS (1989), the categorisation of mild, moderate, and severe valve pathology was established in 1998 or 2006. The publications had considerable heterogeneity with a wide distribution of results. An observational study indicated that with an increased incidence of AS, the risk of developing IE rises. Only one of these 126 publications for these three valve pathologies used analytical statistics. Congenital AS was associated with a higher risk of IE (hazard ratio of 4.9). The results from the literature review parallel those from a survey that we performed to evaluate the knowledge and opinion of clinicians on the term predisposing heart condition. The survey indicated that there is significant uncertainty among clinicians regarding what is considered to be a Duke minor criterion for a predisposing heart condition in a native valve. The results from 318 questionnaires with responses from specialists in the fields of internal medicine, infectious diseases, and cardiology provided a wide range of answers. Their answers also showed that what the participants believed to be a current Duke minor criterion and what they thought should be a minor criterion had a median accordance of 33%. Taken together, these findings demonstrate that there is uncertainty about what is considered a predisposing heart condition for the diagnosis of IE. This uncertainty is demonstrated in our extensive literature review and reflected in our survey among clinicians. The vast majority of studies used only descriptive statistics and included patients prior to the publication of the modified Duke criteria (2000). The tremendous progress in imaging methods and categorisation of valve pathologies since then makes it difficult to interpret the literature review analyses from today’s perspective. Nonetheless, studies on MVP, a prior episode of IE, and BAV had the highest representation in the literature. Among these three pathologies, MVP is most likely to be affected by the evolution of imaging methods, and therefore its risk cannot be quantified. Sensitivity analyses and mathematical models performed on the data obtained in this systematic review may help to further narrow the definition of a predisposing heart condition

An Architecture for User-managed Location Sharing in the Future Internet of Services

Paper of: The 4th International Workshop on Trustworthy Internet of People, Things & Services, co-located with the Internet of Things 2010 Conference, November 29 to December 1, 2010, Tokyo, JapanIn this paper we analyse the problem of providing an user-managed system for sharing the user’s location information in the Future Internet of Services, and propose some architectural mechanisms to support this kind of system. Our approach is based on the work done within Kantara’s UMA WG. Furthermore, we highlight open issues that still need to be addressed in location information sharing scenarios.Enviad

Modeling and control design of a contact-based, electrostatically actuated rotating sphere

The performance of micromirrors in terms of their maximum deflection is often limited due to mechanical constraints in the design. To increase the range of achievable deflection angles, we present a novel concept in which a free-lying sphere with a flat side as reflector can be rotated. Due to the large forces needed to move the sphere, multiple electrostatic actuators are used to cooperatively rotate the sphere in iterative steps by impacts and friction. A parameterized system-level model of the configuration is derived, which considers arbitrary multi-contact scenarios and can be used for simulation, analysis, and control design purposes. Due to the complex, indirect relation between the actuator voltages and the sphere motion, model-based numerical optimization is applied to obtain suitable system inputs. This results in rotation sequences, which can be understood as a sequence of motion primitives, thus transforming the continuous time model into an abstract discrete time model. Based on this, we propose a feedback control strategy for trajectory following, considering model uncertainties by a learning scheme. High precision is achieved by an extension controlling the angular change of each rotation step. The suitability of the overall approach is demonstrated in simulation for maximum angles of 40°, achieving angular velocities of approximately 10°/s

Verifying and Synthesizing Constant-Resource Implementations with Types

We propose a novel type system for verifying that programs correctly implement constant-resource behavior. Our type system extends recent work on automatic amortized resource analysis (AARA), a set of techniques that automatically derive provable upper bounds on the resource consumption of programs. We devise new techniques that build on the potential method to achieve compositionality, precision, and automation. A strict global requirement that a program always maintains constant resource usage is too restrictive for most practical applications. It is sufficient to require that the program's resource behavior remain constant with respect to an attacker who is only allowed to observe part of the program's state and behavior. To account for this, our type system incorporates information flow tracking into its resource analysis. This allows our system to certify programs that need to violate the constant-time requirement in certain cases, as long as doing so does not leak confidential information to attackers. We formalize this guarantee by defining a new notion of resource-aware noninterference, and prove that our system enforces it. Finally, we show how our type inference algorithm can be used to synthesize a constant-time implementation from one that cannot be verified as secure, effectively repairing insecure programs automatically. We also show how a second novel AARA system that computes lower bounds on resource usage can be used to derive quantitative bounds on the amount of information that a program leaks through its resource use. We implemented each of these systems in Resource Aware ML, and show that it can be applied to verify constant-time behavior in a number of applications including encryption and decryption routines, database queries, and other resource-aware functionality.Comment: 30, IEEE S&P 201

Ceramic-based thermoelectric generator processed via spray-coating and laser structuring

Processing technology to improve the manufacturing of thermoelectric generators (TEGs) is a growing field of research. In this paper, an adaptable and scalable process comprising spray-coating and laser structuring for fast and easy TEG manufacturing is presented. The developed process combines additive and subtractive processing technology towards an adaptable ceramic-based TEG, which is applicable at high temperatures and shows a high optimization potential. As a prototype, a TEG based on Ca3Co4O9 (CCO) and Ag on a ceramic substrate was prepared. Microstructural and thermoelectric characterization is shown, reaching up to 1.65 ​μW ​cm−2 at 673 ​K and a ΔT of 100 ​K. The high controllability of the developed process also enables adaptation for different kinds of thermoelectric materials

A SITUATION AWARENESS DRIVEN DESIGN FOR PREDICTIVE MAINTENANCE SYSTEMS: THE CASE OF OIL AND GAS PIPELINE OPERATIONS

The acquisition and processing of events from sensors or enterprise applications in real-time represent an essential part of many application domains such as the Internet of Things (IoT), offering benefits to predict the future condition of equipment to prevent the occurrence of failures. Many organisations already use some form of predictive maintenance to monitor performance or keep track of emerging business situations. However, the optimal design of applications to allow an effective Predictive Mainte-nance System (PMS) capable of analysing and processing large amounts of data is only scarcely exam-ined by Information Systems (IS) research. Due to the number, frequency, and the need for near-real-time evaluation systems must be capable of detecting complex event patterns based on spatial, temporal, or causal relationships on data streams (i.e. via Complex Event Processing). At the same time, however, due to the technical complexity, available systems today are static, since the creation and adaptation of recognisable situations results in slow development cycles. In addition, technical feasibility is only one prerequisite for predictive maintenance. Users must be capable of processing this vast amount of data presented without considerable cognitive effort. Precisely this challenge is even more daunting as op-erational maintenance personnel have to manage business-critical decisions with increasing frequency and short time. Research in Human Factors (HF) suggests Situation Awareness (SA) as a crucial sys-tem’s design paradigm allowing human beings to understand and anticipate the information available effectively. Building on this concept, this paper proposes a PMS for promoting operational decision makers’ Situation Awareness by three design principles (DP): Sensing, Acting, and Tracking. Based on these DPs, we implemented a PMS prototype for a scenario in Oil and Gas pipeline operations. Our finding suggest that the use of SA is of particular interest in realizing effective PMS

Comparison of different methods of aggregation of model ensemble outcomes in the validation and reconstruction of real power plant signals

International audienceSensors are placed at various locations in a production plant to monitor the state of the processes and components. For the plant state monitoring to be effective, the sensors themselves must be monitored for detecting anomalies in their functioning and for reconstructing the correct values of the signals measured. In this work, the task of sensor monitoring and signal reconstruction is tackled with an ensemble of Principal Component Analysis (PCA) models handling individual overlapping groups of sensor signals, randomly generated according to the Random Feature Selection Ensemble (RFSE) technique. The outcomes of these models are combined using a Local Fusion (LF) technique based on the evaluation of the models performance on set of training patterns similar to the test pattern under reconstruction. The performances obtained using the LF method are compared to those obtained using classical aggregation methods such as Simple Mean (SM) Globally weighted average (GWA), Median (MD) and Trimmed Mean (TM), on a real case study concerning 215 signals monitored at a Finnish Pressurized Water Reactor (PWR) nuclear power plant

Infective endocarditis: What are predisposing conditions in native valves?

The term ‘predisposing heart condition’ is used as an indication of antimicrobial prophylaxis to prevent infective endocarditis (IE) and as a criterion for diagnosing IE according to the modified Duke criteria. Whereas the use of the term for antimicrobial prophylaxis is well defined, the criterion for diagnosing IE is not. The general objective of this thesis is to narrow the definition of a predisposing heart condition in ‘native’ valves for the diagnosis of IE. Therefore, we reviewed the literature and the evidence about specific heart conditions reported to be a risk factor for IE. In parallel, we reviewed the imaging technique available at the time these studies were published and compared the results with imaging from today’s perspectives and current definitions of a specific heart condition (i.e. valvular disease). Finally, we evaluated the knowledge and opinion of clinicians about the term predisposing heart condition. Our literature review included 207 studies, the vast majority of which were descriptive. Only a few studies investigated valve pathology as a risk factor for IE via analytical statistics. In addition, three-quarters of all included studies involved patients who presented with IE prior to the publication of the modified Duke criteria. Studies focussing on mitral valve prolapse (MVP, 116 publications), prior IE (96 publications), and bicuspid aortic valve (BAV, 78 publications) provided the most data. The odds ratio of developing IE for a patient who had previously experienced an episode of it was approximately 2.5. The mean proportion of patients with IE plus a history of previous IE was 8.3% (median 7.1%, interquartile range [IQR] 4.9%–10.2%). One study associated BAV with a higher risk of IE (hazard ratio 6.3). In 77 descriptive studies, a median of approximately 6% of patients with IE had BAV as an underlying condition. Our literature review on the evolution of imaging methods indicated, however, a considerable influence of medical progress on the diagnosis of MVP. Six analytical studies and 90 of the 110 descriptive studies included patients prior to the publication of the modified Duke criteria in 2000. For many years, MVP was diagnosed via auscultation only, and echocardiographic means for diagnosis were used in the late 90s. Therefore, both the risk of developing IE and the proportion of patients with IE and MVP as a predisposing factor could not be quantified. The literature review on mitral valve stenosis (MS, 23 publications) and pathologies involving the pulmonary valve (18 publications) and the tricuspid valve (nine publications) provided little data. These publications had inconsistent results and low proportions of patients with IE had these valve pathologies. The significance of aortic valve stenosis (AS, 46 publications), mitral valve insufficiency (MI, 41 publications), and aortic valve insufficiency (AI, 39 publications) as a predisposing heart condition was difficult to assess from today’s perspective because of the progress made in imaging methods; of these studies, 75.6%, 78.6%, and 79.5%, respectively, included patients prior to the publication of the modified Duke criteria in the year 2000. In addition, except for AS (1989), the categorisation of mild, moderate, and severe valve pathology was established in 1998 or 2006. The publications had considerable heterogeneity with a wide distribution of results. An observational study indicated that with an increased incidence of AS, the risk of developing IE rises. Only one of these 126 publications for these three valve pathologies used analytical statistics. Congenital AS was associated with a higher risk of IE (hazard ratio of 4.9). The results from the literature review parallel those from a survey that we performed to evaluate the knowledge and opinion of clinicians on the term predisposing heart condition. The survey indicated that there is significant uncertainty among clinicians regarding what is considered to be a Duke minor criterion for a predisposing heart condition in a native valve. The results from 318 questionnaires with responses from specialists in the fields of internal medicine, infectious diseases, and cardiology provided a wide range of answers. Their answers also showed that what the participants believed to be a current Duke minor criterion and what they thought should be a minor criterion had a median accordance of 33%. Taken together, these findings demonstrate that there is uncertainty about what is considered a predisposing heart condition for the diagnosis of IE. This uncertainty is demonstrated in our extensive literature review and reflected in our survey among clinicians. The vast majority of studies used only descriptive statistics and included patients prior to the publication of the modified Duke criteria (2000). The tremendous progress in imaging methods and categorisation of valve pathologies since then makes it difficult to interpret the literature review analyses from today’s perspective. Nonetheless, studies on MVP, a prior episode of IE, and BAV had the highest representation in the literature. Among these three pathologies, MVP is most likely to be affected by the evolution of imaging methods, and therefore its risk cannot be quantified. Sensitivity analyses and mathematical models performed on the data obtained in this systematic review may help to further narrow the definition of a predisposing heart condition

Birch pollen induces toll-like receptor 4-dependent dendritic cell activation favoring t cell responses

Seasonal exposure to birch pollen (BP) is a major cause of pollinosis. The specific role of Toll-like receptor 4 (TLR4) in BP-induced allergic inflammation and the identification of key factors in birch pollen extracts (BPE) initiating this process remain to be explored. This study aimed to examine (i) the importance of TLR4 for dendritic cell (DC) activation by BPE, (ii) the extent of the contribution of BPE-derived lipopolysaccharide (LPS) and other potential TLR4 adjuvant(s) in BPE, and (iii) the relevance of the TLR4-dependent activation of BPE-stimulated DCs in the initiation of an adaptive immune response. In vitro, activation of murine bone marrow-derived DCs (BMDCs) and human monocyte-derived DCs by BPE or the equivalent LPS (nLPS) was analyzed by flow cytometry. Polymyxin B (PMB), a TLR4 antagonist and TLR4-deficient BMDCs were used to investigate the TLR4 signaling in DC activation. The immunostimulatory activity of BPE was compared to protein-/lipid-depleted BPE-fractions. In co-cultures of BPE-pulsed BMDCs and Bet v 1-specific hybridoma T cells, the influence of the TLR4-dependent DC activation on T cell activation was analyzed. In vivo immunization of IL-4 reporter mice was conducted to study BPE-induced Th2 polarization upon PMB pre-treatment. Murine and human DC activation induced by either BPE or nLPS was inhibited by the TLR4 antagonist or by PMB, and abrogated in TLR4-deficient BMDCs compared to wild-type BMDCs. The lipid-free but not the protein-free fraction showed a reduced capacity to activate the TLR4 signaling and murine DCs. In human DCs, nLPS only partially reproduced the BPE-induced activation intensity. BPE-primed BMDCs efficiently stimulated T cell activation, which was repressed by the TLR4 antagonist or PMB, and the addition of nLPS to Bet v 1 did not reproduce the effect of BPE. In vivo, immunization with BPE induced a significant Th2 polarization, whereas administration of BPE pre-incubated with PMB showed a decreased tendency. These findings suggest that TLR4 is a major pathway by which BPE triggers DC activation that is involved in the initiation of adaptive immune responses. Further characterization of these BP-derived TLR4 adjuvants could provide new candidates for therapeutic strategies targeting specific mechanisms in BP-induced allergic inflammation