Evaluation of fluid transport processes in dental enamel. Methods to assess the relevance of enamel permeability in caries prevention and etching treatments.

This thesis evaluated in vivo and in vitro enamel permeability in different physiological and clinical conditions by means of SEM inspection of replicas of enamel surface obtained from polyvinyl siloxane impressions subsequently later cast in polyether impression ma-terial. This technique, not invasive and risk-free, allows the evaluation of fluid outflow from enamel surface and is able to detect the presence of small quantities of fluid, visu-alized as droplets. Fluid outflow on enamel surface represents enamel permeability. This property has a paramount importance in enamel physiolgy and pathology although its ef-fective role in adhesion, caries pathogenesis and prevention today is still not fully under-stood. The aim of the studies proposed was to evaluate enamel permeability changes in differ-ent conditions and to correlate the findings with the actual knowledge about enamel physiology, caries pathogenesis, fluoride and etchinhg treatments. To obtain confirmed data the replica technique has been supported by others specific techniques such as Ra-man and IR spectroscopy and EDX analysis. The first study carried out visualized fluid movement through dental enamel in vivo con-firmed that enamel is a permeable substrate and demonstrated that age and enamel per-meability are closely related. Examined samples from subjects of different ages showed a decreasing number and size of droplets with increasing age: freshly erupted permanent teeth showed many droplets covering the entire enamel surface. Droplets in permanent teeth were prominent along enamel perikymata. These results obtained through SEM inspection of replicas allowed innovative remarks in enamel physiology. An analogous testing has been developed for evaluation of enamel permeability in primary enamel. The results of this second study showed that primary enamel revealed a substantive permeability with droplets covering the entire enamel sur-face without any specific localization accordingly with histological features, without changes during aging signs of post-eruptive maturation. These results confirmed clinical data that showed a higher caries susceptibility for primary enamel and suggested a strong relationship between this one and enamel permeability. Topical fluoride application represents the gold standard for caries prevention although the mechanism of cariostatic effect of fluoride still needs to be clarified. The effects of topical fluoride application on enamel permeability were evaluated. Particularly two dif-ferent treatments (NaF and APF), with different pH, were examined. The major product of topical fluoride application was the deposition of CaF2-like globules. Replicas inspec-tion before and after both treatments at different times intervals and after specific addi-tional clinical interventions showed that such globule formed in vivo could be removed by professional toothbrushing, sonically and chemically by KOH. The results obtained in relation to enamel permeability showed that fluoride treatments temporarily reduced enamel water permeability when CaF2-like globules were removed. The in vivo perma-nence of decreased enamel permeability after CaF2 globules removal has been demon-strated for 1 h for NaF treated teeth and for at least 7 days for APF treated teeth. Important clinical consideration moved from these results. In fact the caries-preventing action of fluoride application may be due, in part, to its ability to decrease enamel water permeability and CaF2 like-globules seem to be indirectly involved in enamel protection over time maintaining low permeability. Others results obtained by metallographic microscope and SEM/EDX analyses of or-thodontic resins fluoride releasing and not demonstrated the relevance of topical fluo-ride application in decreasing the demineralization marks and modifying the chemical composition of the enamel in the treated area. These data obtained in both the experiments confirmed the efficacy of fluoride in caries prevention and contribute to clarify its mechanism of action. Adhesive dentistry is the gold standard for caries treatment and tooth rehabilitation and is founded on important chemical and physical principles involving both enamel and dentine substrates. Particularly acid etching of dental enamel enamel has usually employed in bonding pro-cedures increasing microscopic roughness. Different acids have been tested in the litera-ture suggesting several etching procedures. The acid-induced structural transformations in enamel after different etching treatments by means of Raman and IR spectroscopy analysis were evaluated and these findings were correlated with enamel permeability. Conventional etching with 37% phosphoric acid gel (H3PO4) for 30 s and etching with 15 % HCl for 120 s were investigated. Raman and IR spectroscopy showed that the treatment with both hydrochloric and phosphoric acids induced a decrease in the carbonate content of the enamel apatite. At the same time, both acids induced the formation of HPO42- ions. After H3PO4 treatment the bands due to the organic component of enamel decreased in intensity, while in-creased after HCl treatment. Replicas of H3PO4 treated enamel showed a strongly reduced permeability while replicas of HCl 15% treated samples showed a maintained permeability. A decrease of the enamel organic component, as resulted after H3PO4 treatment, involves a decrease in enamel permeability, while the increase of the organic matter (achieved by HCl treat-ment) still maintains enamel permeability. These results suggested a correlation between the amount of the organic matter, enamel permeability and caries. The results of the different studies carried out in this thesis contributed to clarify and improve the knowledge about enamel properties with important rebounds in theoretical and clinical aspects of Dentistry.

Modulation Techniques for Multi-Phase Converters and Control Strategies for Multi-Phase Electric Drives

The ever-increasing spread of automation in industry puts the electrical engineer in a central role as a promoter of technological development in a sector such as the use of electricity, which is the basis of all the machinery and productive processes. Moreover the spread of drives for motor control and static converters with structures ever more complex, places the electrical engineer to face new challenges whose solution has as critical elements in the implementation of digital control techniques with the requirements of inexpensiveness and efficiency of the final product. The successfully application of solutions using non-conventional static converters awake an increasing interest in science and industry due to the promising opportunities. However, in the same time, new problems emerge whose solution is still under study and debate in the scientific community During the Ph.D. course several themes have been developed that, while obtaining the recent and growing interest of scientific community, have much space for the development of research activity and for industrial applications. The first area of research is related to the control of three phase induction motors with high dynamic performance and the sensorless control in the high speed range. The management of the operation of induction machine without position or speed sensors awakes interest in the industrial world due to the increased reliability and robustness of this solution combined with a lower cost of production and purchase of this technology compared to the others available in the market. During this dissertation control techniques will be proposed which are able to exploit the total dc link voltage and at the same time capable to exploit the maximum torque capability in whole speed range with good dynamic performance. The proposed solution preserves the simplicity of tuning of the regulators. Furthermore, in order to validate the effectiveness of presented solution, it is assessed in terms of performance and complexity and compared to two other algorithm presented in literature. The feasibility of the proposed algorithm is also tested on induction motor drive fed by a matrix converter. Another important research area is connected to the development of technology for vehicular applications. In this field the dynamic performances and the low power consumption is one of most important goals for an effective algorithm. Towards this direction, a control scheme for induction motor that integrates within a coherent solution some of the features that are commonly required to an electric vehicle drive is presented. The main features of the proposed control scheme are the capability to exploit the maximum torque in the whole speed range, a weak dependence on the motor parameters, a good robustness against the variations of the dc-link voltage and, whenever possible, the maximum efficiency. The second part of this dissertation is dedicated to the multi-phase systems. This technology, in fact, is characterized by a number of issues worthy of investigation that make it competitive with other technologies already on the market. Multiphase systems, allow to redistribute power at a higher number of phases, thus making possible the construction of electronic converters which otherwise would be very difficult to achieve due to the limits of present power electronics. Multiphase drives have an intrinsic reliability given by the possibility that a fault of a phase, caused by the possible failure of a component of the converter, can be solved without inefficiency of the machine or application of a pulsating torque. The control of the magnetic field spatial harmonics in the air-gap with order higher than one allows to reduce torque noise and to obtain high torque density motor and multi-motor applications. In one of the next chapters a control scheme able to increase the motor torque by adding a third harmonic component to the air-gap magnetic field will be presented. Above the base speed the control system reduces the motor flux in such a way to ensure the maximum torque capability. The presented analysis considers the drive constrains and shows how these limits modify the motor performance. The multi-motor applications are described by a well-defined number of multiphase machines, having series connected stator windings, with an opportune permutation of the phases these machines can be independently controlled with a single multi-phase inverter. In this dissertation this solution will be presented and an electric drive consisting of two five-phase PM tubular actuators fed by a single five-phase inverter will be presented. Finally the modulation strategies for a multi-phase inverter will be illustrated. The problem of the space vector modulation of multiphase inverters with an odd number of phases is solved in different way. An algorithmic approach and a look-up table solution will be proposed. The inverter output voltage capability will be investigated, showing that the proposed modulation strategy is able to fully exploit the dc input voltage either in sinusoidal or non-sinusoidal operating conditions. All this aspects are considered in the next chapters. In particular, Chapter 1 summarizes the mathematical model of induction motor. The Chapter 2 is a brief state of art on three-phase inverter. Chapter 3 proposes a stator flux vector control for a three- phase induction machine and compares this solution with two other algorithms presented in literature. Furthermore, in the same chapter, a complete electric drive based on matrix converter is presented. In Chapter 4 a control strategy suitable for electric vehicles is illustrated. Chapter 5 describes the mathematical model of multi-phase induction machines whereas chapter 6 analyzes the multi-phase inverter and its modulation strategies. Chapter 7 discusses the minimization of the power losses in IGBT multi-phase inverters with carrier-based pulse width modulation. In Chapter 8 an extended stator flux vector control for a seven-phase induction motor is presented. Chapter 9 concerns the high torque density applications and in Chapter 10 different fault tolerant control strategies are analyzed. Finally, the last chapter presents a positioning multi-motor drive consisting of two PM tubular five-phase actuators fed by a single five-phase inverter.

Coordination and Control of Autonomous Mobile Robots Swarms by using Particle Swarm Optimization Algorithm and Consensus Theory

This thesis presents some different techniques designed to drive a swarm of robots in an a-priori unknown environment in order to move the group from a starting area to a final one avoiding obstacles. The presented techniques are based on two different theories used alone or in combination: Swarm Intelligence (SI) and Graph Theory. Both theories are based on the study of interactions between different entities (also called agents or units) in Multi- Agent Systems (MAS). The first one belongs to the Artificial Intelligence context and the second one to the Distributed Systems context. These theories, each one from its own point of view, exploit the emergent behaviour that comes from the interactive work of the entities, in order to achieve a common goal. The features of flexibility and adaptability of the swarm have been exploited with the aim to overcome and to minimize difficulties and problems that can affect one or more units of the group, having minimal impact to the whole group and to the common main target. Another aim of this work is to show the importance of the information shared between the units of the group, such as the communication topology, because it helps to maintain the environmental information, detected by each single agent, updated among the swarm. Swarm Intelligence has been applied to the presented technique, through the Particle Swarm Optimization algorithm (PSO), taking advantage of its features as a navigation system. The Graph Theory has been applied by exploiting Consensus and the application of the agreement protocol with the aim to maintain the units in a desired and controlled formation. This approach has been followed in order to conserve the power of PSO and to control part of its random behaviour with a distributed control algorithm like Consensus.

Automotive diesel engine transient operation: modeling, optimization and control

Traditionally, the study of internal combustion engines operation has focused on the steady-state performance. However, the daily driving schedule of automotive engines is inherently related to unsteady conditions. There are various operating conditions experienced by (diesel) engines that can be classified as transient. Besides the variation of the engine operating point, in terms of engine speed and torque, also the warm up phase can be considered as a transient condition. Chapter 2 has to do with this thermal transient condition; more precisely the main issue is the performance of a Selective Catalytic Reduction (SCR) system during cold start and warm up phases of the engine. The proposal of the underlying work is to investigate and identify optimal exhaust line heating strategies, to provide a fast activation of the catalytic reactions on SCR. Chapters 3 and 4 focus the attention on the dynamic behavior of the engine, when considering typical driving conditions. The common approach to dynamic optimization involves the solution of a single optimal-control problem. However, this approach requires the availability of models that are valid throughout the whole engine operating range and actuator ranges. In addition, the result of the optimization is meaningful only if the model is very accurate. Chapter 3 proposes a methodology to circumvent those demanding requirements: an iteration between transient measurements to refine a purpose-built model and a dynamic optimization which is constrained to the model validity region. Moreover all numerical methods required to implement this procedure are presented. Chapter 4 proposes an approach to derive a transient feedforward control system in an automated way. It relies on optimal control theory to solve a dynamic optimization problem for fast transients. From the optimal solutions, the relevant information is extracted and stored in maps spanned by the engine speed and the torque gradient.

Design and Control of Robotic Hands

The application of dexterous robotic hands out of research laboratories has been limited by the intrinsic complexity that these devices present. This is directly reflected as an economically unreasonable cost and a low overall reliability. Within the research reported in this thesis it is shown how the problem of complexity in the design of robotic hands can be tackled, taking advantage of modern technologies (i.e. rapid prototyping), leading to innovative concepts for the design of the mechanical structure, the actuation and sensory systems. The solutions adopted drastically reduce the prototyping and production costs and increase the reliability, reducing the number of parts required and averaging their single reliability factors. In order to get guidelines for the design process, the problem of robotic grasp and manipulation by a dual arm/hand system has been reviewed. In this way, the requirements that should be fulfilled at hardware level to guarantee successful execution of the task has been highlighted. The contribution of this research from the manipulation planning side focuses on the redundancy resolution that arise in the execution of the task in a dexterous arm/hand system. In literature the problem of coordination of arm and hand during manipulation of an object has been widely analyzed in theory but often experimentally demonstrated in simplified robotic setup. Our aim is to cover the lack in the study of this topic and experimentally evaluate it in a complex system as a anthropomorphic arm hand system.

Dynamics and control issues of multi-rotor platforms

This thesis deals with the analytic study of dynamics of Multi--Rotor Unmanned Aerial Vehicles. It is conceived to give a set of mathematical instruments apt to the theoretical study and design of these flying machines. The entire work is organized in analogy with classical academic texts about airplane flight dynamics. First, the non--linear equations of motion are defined and all the external actions are modeled, with particular attention to rotors aerodynamics. All the equations are provided in a form, and with personal expedients, to be directly exploitable in a simulation environment. This has requited an answer to questions like the trim of such mathematical systems. All the treatment is developed aiming at the description of different multi--rotor configurations. Then, the linearized equations of motion are derived. The computation of the stability and control derivatives of the linear model is carried out. The study of static and dynamic stability characteristics is, thus, addressed, showing the influence of the various geometric and aerodynamic parameters of the machine and in particular of the rotors. All the theoretic results are finally utilized in two interesting cases. One concerns the design of control systems for attitude stabilization. The linear model permits the tuning of linear controllers gains and the non--linear model allows the numerical testing. The other case is the study of the performances of an innovative configuration of quad--rotor aircraft. With the non--linear model the feasibility of maneuvers impossible for a traditional quad--rotor is assessed. The linear model is applied to the controllability analysis of such an aircraft in case of actuator block.

Relevance of the pig stomach for the detection of dietary factors and gut maturation and control

In this thesis two approaches were applied to achieve a double general objective. The first chapter was dedicated to the study of the distribution of the expression of genes of several bitter and fat receptor in several gastrointestinal tracts. A set of 7 genes for bitter taste and for 3 genes for fat taste was amplified with real-time PCR from mRNA extracted from 5 gastrointestinal segments of weaned pigs. The presence of gene expression for several chemosensing receptors for bitter and fat taste in different compartments of the stomach confirms that this organ should be considered a player for the early detection of bolus composition. In the second chapter we investigated in young pigs the distribution of butyrate-sensing olfactory receptor (OR51E1) receptor along the GIT, its relation with some endocrine markers, its variation with age, and after interventions affecting the gut environment and intestinal microbiota in piglets and in different tissues. Our results indicate that OR51E1 is strictly related to the normal GIT enteroendocrine activity. In the third chapter we investigated the differential gene expression between oxyntic and pyloric mucosa in seven starter pigs. The obtained data indicate that there is significant differential gene exression between oxintic of the young pig and pyloric mucosa and further functional studies are needed to confirm their physiological importance. In the last chapter, thymol, that has been proposed as an oral alternative to antibiotics in the feed of pigs and broilers, was introduced directly into the stomach of 8 weaned pigs and sampled for gastric oxyntic and pyloric mucosa. The analysis of the whole transcript expression shoes that the stimulation of gastric proliferative activity and the control of digestive activity by thymol can influence positively gastric maturation and function in the weaned pigs.

Education of tobacco use prevention and cessation for dental professionals--a paradigm shift

The use of tobacco continues to be a substantial risk factor in the development and progression of oral cancer, periodontitis, implant failure and poor wound healing. Dental and dental hygiene education providers have made great advances towards the incorporation of tobacco education into their curricula in recent years. Unfortunately, however, both medical and dental education research has consistently reported schools providing only basic knowledge-based curricula that rarely incorporate more effective, behaviourally-based components affecting long-term change. The limited training of oral healthcare students, at least in part, is reflected in practising dental professionals continuing to report offering incomplete tobacco interventions. In order to prepare the next generation of oral healthcare providers, this paper proposes a paradigm shift in how tobacco use prevention and cessation (TUPAC) may be incorporated into existing curricula. It is suggested that schools should carefully consider: to what level of competency should TUPAC be trained in dental and dental hygiene schools; the importance of establishing rapport through good communication skills; the core knowledge level for TUPAC; suggested instructional and assessment strategies; the importance of continuing professional education for the enhancement of TUPAC.

Consensus Report: 2nd European Workshop on Tobacco Use Prevention and Cessation for Oral Health Professionals

Tobacco use has been identified as a major risk factor for oral disorders such as cancer and periodontal disease. Tobacco use cessation (TUC) is associated with the potential for reversal of precancer, enhanced outcomes following periodontal treatment, and better periodontal status compared to patients who continue to smoke. Consequently, helping tobacco users to quit has become a part of both the responsibility of oral health professionals and the general practice of dentistry. TUC should consist of behavioural support, and if accompanied by pharmacotherapy, is more likely to be successful. It is widely accepted that appropriate compensation of TUC counselling would give oral health professionals greater incentives to provide these measures. Therefore, TUC-related compensation should be made accessible to all dental professionals and be in appropriate relation to other therapeutic interventions. International and national associations for oral health professionals are urged to act as advocates to promote population, community and individual initiatives in support of tobacco use prevention and cessation (TUPAC) counselling, including integration in undergraduate and graduate dental curricula. In order to facilitate the adoption of TUPAC strategies by oral health professionals, we propose a level of care model which includes 1) basic care: brief interventions for all patients in the dental practice to identify tobacco users, assess readiness to quit, and request permission to re-address at a subsequent visit, 2) intermediate care: interventions consisting of (brief) motivational interviewing sessions to build on readiness to quit, enlist resources to support change, and to include cessation medications, and 3) advanced care: intensive interventions to develop a detailed quit plan including the use of suitable pharmacotherapy. To ensure that the delivery of effective TUC becomes part of standard care, continuing education courses and updates should be implemented and offered to all oral health professionals on a regular basis.

Secondary prevention through cardiac rehabilitation: from knowledge to implementation. A position paper from the Cardiac Rehabilitation Section of the European Association of Cardiovascular Prevention and Rehabilitation

Increasing awareness of the importance of cardiovascular prevention is not yet matched by the resources and actions within health care systems. Recent publication of the European Commission's European Heart Health Charter in 2008 prompts a review of the role of cardiac rehabilitation (CR) to cardiovascular health outcomes. Secondary prevention through exercise-based CR is the intervention with the best scientific evidence to contribute to decrease morbidity and mortality in coronary artery disease, in particular after myocardial infarction but also incorporating cardiac interventions and chronic stable heart failure. The present position paper aims to provide the practical recommendations on the core components and goals of CR intervention in different cardiovascular conditions, to assist in the design and development of the programmes, and to support healthcare providers, insurers, policy makers and consumers in the recognition of the comprehensive nature of CR. Those charged with responsibility for secondary prevention of cardiovascular disease, whether at European, national or individual centre level, need to consider where and how structured programmes of CR can be delivered to all patients eligible. Thus a novel, disease-oriented document has been generated, where all components of CR for cardiovascular conditions have been revised, presenting both well-established and controversial aspects. A general table applicable to all cardiovascular conditions and specific tables for each clinical disease have been created and commented.