Nutritional strategies to control mycotoxin damages in swine

Mycotoxins are contaminants of agricultural products both in the field and during storage and can enter the food chain through contaminated cereals and foods (milk, meat, and eggs) obtained from animals fed mycotoxin contaminated feeds. Mycotoxins are genotoxic carcinogens that cause health and economic problems. Ochratoxin A and fumonisin B1 have been classified by the International Agency for Research on Cancer in 1993, as “possibly carcinogenic to humans” (class 2B). To control mycotoxins induced damages, different strategies have been developed to reduce the growth of mycotoxigenic fungi as well as to decontaminate and/or detoxify mycotoxin contaminated foods and animal feeds. Critical points, target for these strategies, are: prevention of mycotoxin contamination, detoxification of mycotoxins already present in food and feed, inhibition of mycotoxin absorption in the gastrointestinal tract, reduce mycotoxin induced damages when absorption occurs. Decontamination processes, as indicate by FAO, needs the following requisites to reduce toxic and economic impact of mycotoxins: it must destroy, inactivate, or remove mycotoxins; it must not produce or leave toxic and/or carcinogenic/mutagenic residues in the final products or in food products obtained from animals fed decontaminated feed; it must be capable of destroying fungal spores and mycelium in order to avoiding mycotoxin formation under favorable conditions; it should not adversely affect desirable physical and sensory properties of the feedstuff; it has to be technically and economically feasible. One important approach to the prevention of mycotoxicosis in livestock is the addition in the diets of the non-nutritionally adsorbents that bind mycotoxins preventing the absorption in the gastrointestinal tract. Activated carbons, hydrated sodium calcium aluminosilicate (HSCAS), zeolites, bentonites, and certain clays, are the most studied adsorbent and they possess a high affinity for mycotoxins. In recent years, there has been increasing interest on the hypothesis that the absorption in consumed food can be inhibited by microorganisms in the gastrointestinal tract. Numerous investigators showed that some dairy strains of LAB and bifidobacteria were able to bind aflatoxins effectively. There is a strong need for prevention of the mycotoxin-induced damages once the toxin is ingested. Nutritional approaches, such as supplementation of nutrients, food components, or additives with protective effects against mycotoxin toxicity are assuming increasing interest. Since mycotoxins have been known to produce damages by increasing oxidative stress, the protective properties of antioxidant substances have been extensively investigated. Purpose of the present study was to investigate in vitro and in vivo, strategies to counteract mycotoxin threat particularly in swine husbandry. The Ussing chambers technique was applied in the present study that for the first time to investigate in vitro the permeability of OTA and FB1 through rat intestinal mucosa. Results showed that OTA and FB1 were not absorbed from rat small intestine mucosa. Since in vivo absorption of both mycotoxins normally occurs, it is evident that in these experimental conditions Ussing diffusion chambers were not able to assess the intestinal permeability of OTA and FB1. A large number of LAB strains isolated from feces and different gastrointestinal tract regions of pigs and poultry were screened for their ability to remove OTA, FB1, and DON from bacterial medium. Results of this in vitro study showed low efficacy of isolated LAB strains to reduce OTA, FB1, and DON from bacterial medium. An in vivo trial in rats was performed to evaluate the effects of in-feed supplementation of a LAB strain, Pediococcus pentosaceus FBB61, to counteract the toxic effects induced by exposure to OTA contaminated diets. The study allows to conclude that feed supplementation with P. pentosaceus FBB61 ameliorates the oxidative status in liver, and lowers OTA induced oxidative damage in liver and kidney if diet was contaminated by OTA. This P. pentosaceus FBB61 feature joined to its bactericidal activity against Gram positive bacteria and its ability to modulate gut microflora balance in pigs, encourage additional in vivo experiments in order to better understand the potential role of P. pentosaceus FBB61 as probiotic for farm animals and humans. In the present study, in vivo trial on weaned piglets fed FB1 allow to conclude that feeding of 7.32 ppm of FB1 for 6 weeks did not impair growth performance. Deoxynivalenol contamination of feeds was evaluated in an in vivo trial on weaned piglets. The comparison between growth parameters of piglets fed DON contaminated diet and contaminated diet supplemented with the commercial product did not reach the significance level but piglet growth performances were numerically improved when the commercial product was added to DON contaminated diet. Further studies are needed to improve knowledge on mycotoxins intestinal absorption, mechanism for their detoxification in feeds and foods, and nutritional strategies to reduce mycotoxins induced damages in animals and humans. The multifactorial approach acting on each of the various steps could be a promising strategy to counteract mycotoxins damages.

Coordinated Control of Robotic Swarms in Unknown Environments

This thesis gathers the work carried out by the author in the last three years of research and it concerns the study and implementation of algorithms to coordinate and control a swarm of mobile robots moving in unknown environments. In particular, the author's attention is focused on two different approaches in order to solve two different problems. The first algorithm considered in this work deals with the possibility of decomposing a main complex task in many simple subtasks by exploiting the decentralized implementation of the so called \emph{Null Space Behavioral} paradigm. This approach to the problem of merging different subtasks with assigned priority is slightly modified in order to handle critical situations that can be detected when robots are moving through an unknown environment. In fact, issues can occur when one or more robots got stuck in local minima: a smart strategy to avoid deadlock situations is provided by the author and the algorithm is validated by simulative analysis. The second problem deals with the use of concepts borrowed from \emph{graph theory} to control a group differential wheel robots by exploiting the Laplacian solution of the consensus problem. Constraints on the swarm communication topology have been introduced by the use of a range and bearing platform developed at the Distributed Intelligent Systems and Algorithms Laboratory (DISAL), EPFL (Lausanne, CH) where part of author's work has been carried out. The control algorithm is validated by demonstration and simulation analysis and, later, is performed by a team of four robots engaged in a formation mission. To conclude, the capabilities of the algorithm based on the local solution of the consensus problem for differential wheel robots are demonstrated with an application scenario, where nine robots are engaged in a hunting task.

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.

Security control brought back to the user

The activity of the Ph.D. student Juri Luca De Coi involved the research field of policy languages and can be divided in three parts. The first part of the Ph.D. work investigated the state of the art in policy languages, ending up with: (i) identifying the requirements up-to-date policy languages have to fulfill; (ii) defining a policy language able to fulfill such requirements (namely, the Protune policy language); and (iii) implementing an infrastructure able to enforce policies expressed in the Protune policy language. The second part of the Ph.D. work focused on simplifying the activity of defining policies and ended up with: (i) identifying a subset of the controlled natural language ACE to express Protune policies; (ii) implementing a mapping between ACE policies and Protune policies; and (iii) adapting the ACE Editor to guide users step by step when defining ACE policies. The third part of the Ph.D. work tested the feasibility of the chosen approach by applying it to meaningful real-world problems, among which: (i) development of a security layer on top of RDF stores; and (ii) efficient policy-aware access to metadata stores. The research activity has been performed in tight collaboration with the Leibniz Universität Hannover and further European partners within the projects REWERSE, TENCompetence and OKKAM.

Mortgage securitization and its credit risk control

This dissertation concentrate on the mortgage securitization and its credit risk, which are criticized as the main causes of the financial crisis. From the point of the veiw of mortgage's evolution, the nature, structure and function of mortgage has been radically changed, yet the mortgage law did not give appropriate response to this market change. Meanwhile, the U.S legilslations facilitating the mortgage securitization also have rotten the legal foundations for mortgage market self-regulation and sustained development. In contrast, the EU covered bond system has kept financial stability for 200 years' time, and their statutory approach has been proved to be able to control the credit risk and incentive problems very well, in combination of market self-regulation and public regulation. So the future reform should be directed to strengthen the market's capacity of self-regulation and improve the public regulation. For the development of mortgage securitization in China, it is suggested to introduce the EU covered bond system for the reason of the equilibrium between funding efficiency and financial stability.

Spinal cord injury: assessment of autonomic state-dependent control of cardiovascular system and body core temperature

Spinal cord injury (SCI) results not only in paralysis; but it is also associated with a range of autonomic dysregulation that can interfere with cardiovascular, bladder, bowel, temperature, and sexual function. The entity of the autonomic dysfunction is related to the level and severity of injury to descending autonomic (sympathetic) pathways. For many years there was limited awareness of these issues and the attention given to them by the scientific and medical community was scarce. Yet, even if a new system to document the impact of SCI on autonomic function has recently been proposed, the current standard of assessment of SCI (American Spinal Injury Association (ASIA) examination) evaluates motor and sensory pathways, but not severity of injury to autonomic pathways. Beside the severe impact on quality of life, autonomic dysfunction in persons with SCI is associated with increased risk of cardiovascular disease and mortality. Therefore, obtaining information regarding autonomic function in persons with SCI is pivotal and clinical examinations and laboratory evaluations to detect the presence of autonomic dysfunction and quantitate its severity are mandatory. Furthermore, previous studies demonstrated that there is an intimate relationship between the autonomic nervous system and sleep from anatomical, physiological, and neurochemical points of view. Although, even if previous epidemiological studies demonstrated that sleep problems are common in spinal cord injury (SCI), so far only limited polysomnographic (PSG) data are available. Finally, until now, circadian and state dependent autonomic regulation of blood pressure (BP), heart rate (HR) and body core temperature (BcT) were never assessed in SCI patients. Aim of the current study was to establish the association between the autonomic control of the cardiovascular function and thermoregulation, sleep parameters and increased cardiovascular risk in SCI patients.

Nonlinear Observers for Sensorless Control of Permanent Magnet Synchronous Motors

In this thesis, the industrial application of control a Permanent Magnet Synchronous Motor in a sensorless configuration has been faced, and in particular the task of estimating the unknown “parameters” necessary for the application of standard motor control algorithms. In literature several techniques have been proposed to cope with this task, among them the technique based on model-based nonlinear observer has been followed. The hypothesis of neglecting the mechanical dynamics from the motor model has been applied due to practical and physical considerations, therefore only the electromagnetic dynamics has been used for the observers design. First observer proposed is based on stator currents and Stator Flux dynamics described in a generic rotating reference frame. Stator flux dynamics are known apart their initial conditions which are estimated, with speed that is also unknown, through the use of the Adaptive Theory. The second observer proposed is based on stator currents and Rotor Flux dynamics described in a self-aligning reference frame. Rotor flux dynamics are described in the stationary reference frame exploiting polar coordinates instead of classical Cartesian coordinates, by means the estimation of amplitude and speed of the rotor flux. The stability proof is derived in a Singular Perturbation Framework, which allows for the use the current estimation errors as a measure of rotor flux estimation errors. The stability properties has been derived using a specific theory for systems with time scale separation, which guarantees a semi-global practical stability. For the two observer ideal simulations and real simulations have been performed to prove the effectiveness of the observers proposed, real simulations on which the effects of the Inverter nonlinearities have been introduced, showing the already known problems of the model-based observers for low speed applications.

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.

Fault detection, diagnosis and active fault tolerant control for a satellite attitude control system

Modern control systems are becoming more and more complex and control algorithms more and more sophisticated. Consequently, Fault Detection and Diagnosis (FDD) and Fault Tolerant Control (FTC) have gained central importance over the past decades, due to the increasing requirements of availability, cost efficiency, reliability and operating safety. This thesis deals with the FDD and FTC problems in a spacecraft Attitude Determination and Control System (ADCS). Firstly, the detailed nonlinear models of the spacecraft attitude dynamics and kinematics are described, along with the dynamic models of the actuators and main external disturbance sources. The considered ADCS is composed of an array of four redundant reaction wheels. A set of sensors provides satellite angular velocity, attitude and flywheel spin rate information. Then, general overviews of the Fault Detection and Isolation (FDI), Fault Estimation (FE) and Fault Tolerant Control (FTC) problems are presented, and the design and implementation of a novel diagnosis system is described. The system consists of a FDI module composed of properly organized model-based residual filters, exploiting the available input and output information for the detection and localization of an occurred fault. A proper fault mapping procedure and the nonlinear geometric approach are exploited to design residual filters explicitly decoupled from the external aerodynamic disturbance and sensitive to specific sets of faults. The subsequent use of suitable adaptive FE algorithms, based on the exploitation of radial basis function neural networks, allows to obtain accurate fault estimations. Finally, this estimation is actively exploited in a FTC scheme to achieve a suitable fault accommodation and guarantee the desired control performances. A standard sliding mode controller is implemented for attitude stabilization and control. Several simulation results are given to highlight the performances of the overall designed system in case of different types of faults affecting the ADCS actuators and sensors.

NLGA based Active Control in Aerospace: fault tolerability, disturbance rejection, and parameter estimation

A new control scheme has been presented in this thesis. Based on the NonLinear Geometric Approach, the proposed Active Control System represents a new way to see the reconfigurable controllers for aerospace applications. The presence of the Diagnosis module (providing the estimation of generic signals which, based on the case, can be faults, disturbances or system parameters), mean feature of the depicted Active Control System, is a characteristic shared by three well known control systems: the Active Fault Tolerant Controls, the Indirect Adaptive Controls and the Active Disturbance Rejection Controls. The standard NonLinear Geometric Approach (NLGA) has been accurately investigated and than improved to extend its applicability to more complex models. The standard NLGA procedure has been modified to take account of feasible and estimable sets of unknown signals. Furthermore the application of the Singular Perturbations approximation has led to the solution of Detection and Isolation problems in scenarios too complex to be solved by the standard NLGA. Also the estimation process has been improved, where multiple redundant measuremtent are available, by the introduction of a new algorithm, here called "Least Squares - Sliding Mode". It guarantees optimality, in the sense of the least squares, and finite estimation time, in the sense of the sliding mode. The Active Control System concept has been formalized in two controller: a nonlinear backstepping controller and a nonlinear composite controller. Particularly interesting is the integration, in the controller design, of the estimations coming from the Diagnosis module. Stability proofs are provided for both the control schemes. Finally, different applications in aerospace have been provided to show the applicability and the effectiveness of the proposed NLGA-based Active Control System.

Combined modality treatment improves tumor control and overall survival in patients with early stage Hodgkin's lymphoma: a systematic review

Combined modality treatment (CMT) of chemotherapy followed by localized radiotherapy is standard treatment for patients with early stage Hodgkin's lymphoma. However, the role of radiotherapy has been questioned recently and some clinical study groups advocate chemotherapy only for this indication. We thus performed a systematic review with meta-analysis of randomized controlled trials comparing chemotherapy alone with CMT in patients with early stage Hodgkin's lymphoma with respect to response rate, tumor control and overall survival (OS). We searched Medline, EMBASE and the Cochrane Library as well as conference proceedings from January 1980 to February 2009 for randomized controlled trials comparing chemotherapy alone versus the same chemotherapy regimen plus radiotherapy. Progression free survival and similar outcomes were analyzed together as tumor control. Effect measures used were hazard ratios for OS and tumor control as well as relative risks for complete response (CR). Meta-analyses were performed using RevMan5. Five randomized controlled trials involving 1,245 patients were included. The hazard ratio (HR) was 0.41 (95% confidence interval (CI) 0.25 to 0.66) for tumor control and 0.40 (95% CI 0.27 to 0.59) for OS for patients receiving CMT compared to chemotherapy alone. CR rates were similar between treatment groups. In sensitivity analyses another 6 trials were included that did not fulfill the inclusion criteria of our protocol but were considered relevant to the topic. These trials underlined the results of the main analysis. In conclusion, adding radiotherapy to chemotherapy improves tumor control and OS in patients with early stage Hodgkin's lymphoma.

A pilot case-control study of behavioral aspects and risk factors in Swiss climbers

Climbing is a popular sport in Switzerland, with approximately 100 000 active participants. There is an inherent risk of falls, overuse and stress-related trauma, with a reported injury rate of 4.2 injuries per 1000 climbing hours.

The Constitutional-Judicial Control of the Legislative and Executive Powers in Central and Eastern European Countries

This project looked at the nature, contents, methods, means and legal and political effects of the influence that constitutional courts exercise upon the legislative and executive powers in the newly established democracies of Central and Eastern Europe. The basic hypothesis was that these courts work to provide a limitation of political power within the framework of the principal constitutional values and that they force the legislature and executive to exercise their powers and duties in strict accordance with the constitution. Following a study of the documentary sources, including primarily the relevant constitutional and statutory provisions and decisions of constitutional courts, Mr. Cvetkovski prepared a questionnaire on various aspects of the topics researched and sent it to the respective constitutional courts. A series of direct interviews with court officials in six of the ten countries then served to clarify a large number of questions relating to differences in procedures etc. that arose from the questionnaires. As a final stage, the findings were compared with those described in recent publications on constitutional control in general and in Central and Eastern Europe in particular. The study began by considering the constitutional and political environment of the constitutional courts' activities in controlling legislative and executive powers, which in all countries studied are based on the principles of the rule of law and the separation of powers. All courts are separate bodies with special status in terms of constitutional law and are independent of other political and judicial institutions. The range of matters within their jurisdiction is set by the constitution of the country in question but in all cases can be exercised only with the framework of procedural rules. This gives considerable significance to the question of who sets these rules and different countries have dealt with it in different ways. In some there is a special constitutional law with the same legal force as the constitution itself (Croatia), the majority of countries allow for regulation by an ordinary law, Macedonia gives the court the autonomy to create and change its own rules of procedure, while in Hungary the parliament fixes the rules on procedure at the suggestion of the constitutional court. The question of the appointment of constitutional judges was also considered and of the mechanisms for ensuring their impartiality and immunity. In the area of the courts' scope for providing normative control, considerable differences were found between the different countries. In some cases the courts' jurisdiction is limited to the normative acts of the respective parliaments, and there is generally no provision for challenging unconstitutional omissions by legislation and the executive. There are, however, some situations in which they may indirectly evaluate the constitutionality of legislative omissions, as when the constitution contains provision for a time limit on enacting legislation, when the parliament has made an omission in drafting a law which violates the constitutional provisions, or when a law grants favours to certain groups while excluding others, thereby violating the equal protection clause of the constitution. The control of constitutionality of normative acts can be either preventive or repressive, depending on whether it is implemented before or after the promulgation of the law or other enactment being challenged. In most countries in the region the constitutional courts provide only repressive control, although in Hungary and Poland the courts are competent to perform both preventive and repressive norm control, while in Romania the court's jurisdiction is limited to preventive norm control. Most countries are wary of vesting constitutional courts with preventive norm control because of the danger of their becoming too involved in the day-to-day political debate, but Mr. Cvetkovski points out certain advantages of such control. If combined with a short time limit it can provide early clarification of a constitutional issue, secondly it avoids the problems arising if a law that has been in force for some years is declared to be unconstitutional, and thirdly it may help preserve the prestige of the legislation. Its disadvantages include the difficulty of ascertaining the actual and potential consequences of a norm without the empirical experience of the administration and enforcement of the law, the desirability of a certain distance from the day-to-day arguments surrounding the political process of legislation, the possible effects of changing social and economic conditions, and the danger of placing obstacles in the way of rapid reactions to acute situations. In the case of repressive norm control, this can be either abstract or concrete. The former is initiated by the supreme state organs in order to protect abstract constitutional order and the latter is initiated by ordinary courts, administrative authorities or by individuals. Constitutional courts cannot directly oblige the legislature and executive to pass a new law and this remains a matter of legislative and executive political responsibility. In the case of Poland, the parliament even has the power to dismiss a constitutional court decision by a special majority of votes, which means that the last word lies with the legislature. As the current constitutions of Central and Eastern European countries are newly adopted and differ significantly from the previous ones, the courts' interpretative functions should ensure a degree of unification in the application of the constitution. Some countries (Bulgaria, Hungary, Poland, Slovakia and Russia) provide for the constitutional courts' decisions to have a binding role on the constitutions. While their decisions inevitably have an influence on the actions of public bodies, they do not set criteria for political behaviour, which depends rather on the overall political culture and traditions of the society. All constitutions except that of Belarus, provide for the courts to have jurisdiction over conflicts arising from the distribution of responsibilities between different organs and levels in the country, as well for impeachment procedures against the head of state, and for determining the constitutionality of political parties (except in Belarus, Hungary, Russia and Slovakia). All the constitutions studied guarantee individual rights and freedoms and most courts have jurisdiction over complaints of violation of these rights by the constitution. All courts also have some jurisdiction over international agreements and treaties, either directly (Belarus, Bulgaria and Hungary) before the treaty is ratified, or indirectly (Croatia, Czech Republic, Macedonia, Romania, Russia and Yugoslavia). In each country the question of who may initiate proceedings of norm control is of central importance and is usually regulated by the constitution itself. There are three main possibilities: statutory organs, normal courts and private individuals and the limitations on each of these is discussed in the report. Most courts are limited in their rights to institute ex officio a full-scale review of a point of law, and such rights as they do have rarely been used. In most countries courts' decisions do not have any binding force but must be approved by parliament or impose on parliament the obligation to bring the relevant law into conformity within a certain period. As a result, the courts' position is generally weaker than in other countries in Europe, with parliament remaining the supreme body. In the case of preventive norm control a finding of unconstitutionality may act to suspend the law and or to refer it back to the legislature, where in countries such as Romania it may even be overturned by a two-thirds majority. In repressive norm control a finding of unconstitutionality generally serves to take the relevant law out of legal force from the day of publication of the decision or from another date fixed by the court. If the law is annulled retrospectively this may or may not bring decisions of criminal courts under review, depending on the provisions laid down in the relevant constitution. In cases relating to conflicts of competencies the courts' decisions tend to be declaratory and so have a binding effect inter partes. In the case of a review of an individual act, decisions generally become effective primarily inter partes but is the individual act has been based on an unconstitutional generally binding normative act of the legislature or executive, the findings has quasi-legal effect as it automatically initiates special proceedings in which the law or other regulation is to be annulled or abrogated with effect erga omnes. This wards off further application of the law and thus further violations of individual constitutional rights, but also discourages further constitutional complaints against the same law. Thus the success of one individual's complaint extends to everyone else whose rights have equally been or might have been violated by the respective law. As the body whose act is repealed is obliged to adopt another act and in doing so is bound by the legal position of the constitutional court on the violation of constitutionally guaranteed freedoms and rights of the complainant, in this situation the decision of the constitutional court has the force of a precedent.

Separation of Ownership from Control and Discretionary Managerial Behaviour in a Transition Economy

This study was the final stage of a four-year study of managerial behaviour and company performance in Bulgaria and examined the influence of changing ownership and control structures of companies on managerial behaviour and initiative. It provides a theoretical summary of the specific types of ownership, control, governance structures and managerial strategies in the Bulgarian transitional economy during 1992-1996. It combines two theoretical approaches, the property-rights approach to show concentrated property-rights structure and private and majority types of control as determinants of efficient enterprise risk bearing and constrained managerial discretion, and the agency theory approach to reveal the efficient role of direct non-market governance mechanisms over managers. Mr. Peev also used empirical information collected from the Central Statistical office in Bulgaria, three different enterprise investigations of corporatised state-owned enterprises between 1992 and 1994, and his own data base of privatised and private de novo industrial companies in 1996-1996. The project gives a detailed description of the main property-rights structures in Bulgaria at the present time and of the various control structures related to these. It found that there is a strong owner type of control in private and privatised firms, although, contrary to expectations, 100% state -owned enterprises tended to be characterised by a separation of ownership from control, leaving scope for managerial discretion. Mr. Peev predicts that after the forthcoming mass privatisation, many companies will acquire a dispersed ownership structure and there will be a greater separation of ownership from control and potential or inefficient managerial behaviour. The next aspect considered in detail was governance structures and the influence of the generally unstable macroeconomic environment in the country during the period in question. In examining managerial strategies, Mr. Peev divided the years since 1990 into 3 periods. Even in the first period (1990-1992) there were some signs of a more efficient role for managers and between 1992 and 1994 the picture of control structures and different managerial behaviour in state-owned companies became more diversified. Managerial strategies identified included managerial initiatives for privatisation, where managers took initiative in resolving problems of property rights and introducing restructuring measures and privatisation proposals, managerial initiatives for restructuring without privatisation, and passive adjustment and passive management, where managers seek outside services for marketing, finance management, etc. in order to adjust to the new environment. During 1995-1996 some similarities and differences between the managerial behaviour of privatised and state-owned firms emerged. Firstly, the former have undergone many changes in investment and technology, while managers of state-owned companies have changed little in this field, indicating that the private property-rights structure is more efficient for the long-term adaptation of enterprises. In the area of strategies relating to product quality, marketing, and pricing policy there was little difference between managers of private, privatised and state-owned firms. The most passive managerial behaviour was found in non-incorporated state-owned firms, although these have only an insignificant stake in the economy.