11 resultados para theories of value
em AMS Tesi di Dottorato - Alm@DL - Università di Bologna
Resumo:
The first part of the thesis concerns the study of inflation in the context of a theory of gravity called "Induced Gravity" in which the gravitational coupling varies in time according to the dynamics of the very same scalar field (the "inflaton") driving inflation, while taking on the value measured today since the end of inflation. Through the analytical and numerical analysis of scalar and tensor cosmological perturbations we show that the model leads to consistent predictions for a broad variety of symmetry-breaking inflaton's potentials, once that a dimensionless parameter entering into the action is properly constrained. We also discuss the average expansion of the Universe after inflation (when the inflaton undergoes coherent oscillations about the minimum of its potential) and determine the effective equation of state. Finally, we analyze the resonant and perturbative decay of the inflaton during (p)reheating. The second part is devoted to the study of a proposal for a quantum theory of gravity dubbed "Horava-Lifshitz (HL) Gravity" which relies on power-counting renormalizability while explicitly breaking Lorentz invariance. We test a pair of variants of the theory ("projectable" and "non-projectable") on a cosmological background and with the inclusion of scalar field matter. By inspecting the quadratic action for the linear scalar cosmological perturbations we determine the actual number of propagating degrees of freedom and realize that the theory, being endowed with less symmetries than General Relativity, does admit an extra gravitational degree of freedom which is potentially unstable. More specifically, we conclude that in the case of projectable HL Gravity the extra mode is either a ghost or a tachyon, whereas in the case of non-projectable HL Gravity the extra mode can be made well-behaved for suitable choices of a pair of free dimensionless parameters and, moreover, turns out to decouple from the low-energy Physics.
Resumo:
The notion of commodification is a fascinating one. It entails many facets, ranging from subjective debates on desirability of commodification to in depth economic analyses of objects of value and their corresponding markets. Commodity theory is therefore not just defined by a single debate, but spans a plethora of different discussions. This thesis maps and situates those theories and debates and selects one specific strain to investigate further. This thesis argues that commodity theory in its optima forma deals with the investigation into what sets commodities apart from non-commodities. It proceeds to examine the many given answers to this question by scholars ranging from the mid 1800’s to the late 2000’s. Ultimately, commodification is defined as a process in which an object becomes an element of the total wealth of societies in which the capitalist mode of production prevails. In doing so, objects must meet observables, or indicia, of commodification provided by commodity theories. Problems arise when objects are clearly part of the total wealth in societies without meeting established commodity indicia. In such cases, objects are part of the total wealth of a society without counting as a commodity. This thesis examines this phenomenon in relation to the novel commodities of audiences and data. It explains how these non-commodities (according to classical theories) are still essential elements of industry. The thesis then takes a deep dive into commodity theory using the theory on the construction of social reality by John Searle.
Resumo:
Quasars and AGN play an important role in many aspects of the modern cosmology. Of particular interest is the issue of the interplay between AGN activity and formation and evolution of galaxies and structures. Studies on nearby galaxies revealed that most (and possibly all) galaxy nuclei contain a super-massive black hole (SMBH) and that between a third and half of them are showing some evidence of activity (Kormendy and Richstone, 1995). The discovery of a tight relation between black holes mass and velocity dispersion of their host galaxy suggests that the evolution of the growth of SMBH and their host galaxy are linked together. In this context, studying the evolution of AGN, through the luminosity function (LF), is fundamental to constrain the theories of galaxy and SMBH formation and evolution. Recently, many theories have been developed to describe physical processes possibly responsible of a common formation scenario for galaxies and their central black hole (Volonteri et al., 2003; Springel et al., 2005a; Vittorini et al., 2005; Hopkins et al., 2006a) and an increasing number of observations in different bands are focused on collecting larger and larger quasar samples. Many issues remain however not yet fully understood. In the context of the VVDS (VIMOS-VLT Deep Survey), we collected and studied an unbiased sample of spectroscopically selected faint type-1 AGN with a unique and straightforward selection function. Indeed, the VVDS is a large, purely magnitude limited spectroscopic survey of faint objects, free of any morphological and/or color preselection. We studied the statistical properties of this sample and its evolution up to redshift z 4. Because of the contamination of the AGN light by their host galaxies at the faint magnitudes explored by our sample, we observed that a significant fraction of AGN in our sample would be missed by the UV excess and morphological criteria usually adopted for the pre-selection of optical QSO candidates. If not properly taken into account, this failure in selecting particular sub-classes of AGN could, in principle, affect some of the conclusions drawn from samples of AGN based on these selection criteria. The absence of any pre-selection in the VVDS leads us to have a very complete sample of AGN, including also objects with unusual colors and continuum shape. The VVDS AGN sample shows in fact redder colors than those expected by comparing it, for example, with the color track derived from the SDSS composite spectrum. In particular, the faintest objects have on average redder colors than the brightest ones. This can be attributed to both a large fraction of dust-reddened objects and a significant contamination from the host galaxy. We have tested these possibilities by examining the global spectral energy distribution of each object using, in addition to the U, B, V, R and I-band magnitudes, also the UV-Galex and the IR-Spitzer bands, and fitting it with a combination of AGN and galaxy emission, allowing also for the possibility of extinction of the AGN flux. We found that for 44% of our objects the contamination from the host galaxy is not negligible and this fraction decreases to 21% if we restrict the analysis to a bright subsample (M1450 <-22.15). Our estimated integral surface density at IAB < 24.0 is 500 AGN per square degree, which represents the highest surface density of a spectroscopically confirmed sample of optically selected AGN. We derived the luminosity function in B-band for 1.0 < z < 3.6 using the 1/Vmax estimator. Our data, more than one magnitude fainter than previous optical surveys, allow us to constrain the faint part of the luminosity function up to high redshift. A comparison of our data with the 2dF sample at low redshift (1 < z < 2.1) shows that the VDDS data can not be well fitted with the pure luminosity evolution (PLE) models derived by previous optically selected samples. Qualitatively, this appears to be due to the fact that our data suggest the presence of an excess of faint objects at low redshift (1.0 < z < 1.5) with respect to these models. By combining our faint VVDS sample with the large sample of bright AGN extracted from the SDSS DR3 (Richards et al., 2006b) and testing a number of different evolutionary models, we find that the model which better represents the combined luminosity functions, over a wide range of redshift and luminosity, is a luminosity dependent density evolution (LDDE) model, similar to those derived from the major Xsurveys. Such a parameterization allows the redshift of the AGN density peak to change as a function of luminosity, thus fitting the excess of faint AGN that we find at 1.0 < z < 1.5. On the basis of this model we find, for the first time from the analysis of optically selected samples, that the peak of the AGN space density shifts significantly towards lower redshift going to lower luminosity objects. The position of this peak moves from z 2.0 for MB <-26.0 to z 0.65 for -22< MB <-20. This result, already found in a number of X-ray selected samples of AGN, is consistent with a scenario of “AGN cosmic downsizing”, in which the density of more luminous AGN, possibly associated to more massive black holes, peaks earlier in the history of the Universe (i.e. at higher redshift), than that of low luminosity ones, which reaches its maximum later (i.e. at lower redshift). This behavior has since long been claimed to be present in elliptical galaxies and it is not easy to reproduce it in the hierarchical cosmogonic scenario, where more massive Dark Matter Halos (DMH) form on average later by merging of less massive halos.
Resumo:
Recently, a rising interest in political and economic integration/disintegration issues has been developed in the political economy field. This growing strand of literature partly draws on traditional issues of fiscal federalism and optimum public good provision and focuses on a trade-off between the benefits of centralization, arising from economies of scale or externalities, and the costs of harmonizing policies as a consequence of the increased heterogeneity of individual preferences in an international union or in a country composed of at least two regions. This thesis stems from this strand of literature and aims to shed some light on two highly relevant aspects of the political economy of European integration. The first concerns the role of public opinion in the integration process; more precisely, how economic benefits and costs of integration shape citizens' support for European Union (EU) membership. The second is the allocation of policy competences among different levels of government: European, national and regional. Chapter 1 introduces the topics developed in this thesis by reviewing the main recent theoretical developments in the political economy analysis of integration processes. It is structured as follows. First, it briefly surveys a few relevant articles on economic theories of integration and disintegration processes (Alesina and Spolaore 1997, Bolton and Roland 1997, Alesina et al. 2000, Casella and Feinstein 2002) and discusses their relevance for the study of the impact of economic benefits and costs on public opinion attitude towards the EU. Subsequently, it explores the links existing between such political economy literature and theories of fiscal federalism, especially with regard to normative considerations concerning the optimal allocation of competences in a union. Chapter 2 firstly proposes a model of citizens’ support for membership of international unions, with explicit reference to the EU; subsequently it tests the model on a panel of EU countries. What are the factors that influence public opinion support for the European Union (EU)? In international relations theory, the idea that citizens' support for the EU depends on material benefits deriving from integration, i.e. whether European integration makes individuals economically better off (utilitarian support), has been common since the 1970s, but has never been the subject of a formal treatment (Hix 2005). A small number of studies in the 1990s have investigated econometrically the link between national economic performance and mass support for European integration (Eichenberg and Dalton 1993; Anderson and Kalthenthaler 1996), but only making informal assumptions. The main aim of Chapter 2 is thus to propose and test our model with a view to providing a more complete and theoretically grounded picture of public support for the EU. Following theories of utilitarian support, we assume that citizens are in favour of membership if they receive economic benefits from it. To develop this idea, we propose a simple political economic model drawing on the recent economic literature on integration and disintegration processes. The basic element is the existence of a trade-off between the benefits of centralisation and the costs of harmonising policies in presence of heterogeneous preferences among countries. The approach we follow is that of the recent literature on the political economy of international unions and the unification or break-up of nations (Bolton and Roland 1997, Alesina and Wacziarg 1999, Alesina et al. 2001, 2005a, to mention only the relevant). The general perspective is that unification provides returns to scale in the provision of public goods, but reduces each member state’s ability to determine its most favoured bundle of public goods. In the simple model presented in Chapter 2, support for membership of the union is increasing in the union’s average income and in the loss of efficiency stemming from being outside the union, and decreasing in a country’s average income, while increasing heterogeneity of preferences among countries points to a reduced scope of the union. Afterwards we empirically test the model with data on the EU; more precisely, we perform an econometric analysis employing a panel of member countries over time. The second part of Chapter 2 thus tries to answer the following question: does public opinion support for the EU really depend on economic factors? The findings are broadly consistent with our theoretical expectations: the conditions of the national economy, differences in income among member states and heterogeneity of preferences shape citizens’ attitude towards their country’s membership of the EU. Consequently, this analysis offers some interesting policy implications for the present debate about ratification of the European Constitution and, more generally, about how the EU could act in order to gain more support from the European public. Citizens in many member states are called to express their opinion in national referenda, which may well end up in rejection of the Constitution, as recently happened in France and the Netherlands, triggering a European-wide political crisis. These events show that nowadays understanding public attitude towards the EU is not only of academic interest, but has a strong relevance for policy-making too. Chapter 3 empirically investigates the link between European integration and regional autonomy in Italy. Over the last few decades, the double tendency towards supranationalism and regional autonomy, which has characterised some European States, has taken a very interesting form in this country, because Italy, besides being one of the founding members of the EU, also implemented a process of decentralisation during the 1970s, further strengthened by a constitutional reform in 2001. Moreover, the issue of the allocation of competences among the EU, the Member States and the regions is now especially topical. The process leading to the drafting of European Constitution (even if then it has not come into force) has attracted much attention from a constitutional political economy perspective both on a normative and positive point of view (Breuss and Eller 2004, Mueller 2005). The Italian parliament has recently passed a new thorough constitutional reform, still to be approved by citizens in a referendum, which includes, among other things, the so called “devolution”, i.e. granting the regions exclusive competence in public health care, education and local police. Following and extending the methodology proposed in a recent influential article by Alesina et al. (2005b), which only concentrated on the EU activity (treaties, legislation, and European Court of Justice’s rulings), we develop a set of quantitative indicators measuring the intensity of the legislative activity of the Italian State, the EU and the Italian regions from 1973 to 2005 in a large number of policy categories. By doing so, we seek to answer the following broad questions. Are European and regional legislations substitutes for state laws? To what extent are the competences attributed by the European treaties or the Italian Constitution actually exerted in the various policy areas? Is their exertion consistent with the normative recommendations from the economic literature about their optimum allocation among different levels of government? The main results show that, first, there seems to be a certain substitutability between EU and national legislations (even if not a very strong one), but not between regional and national ones. Second, the EU concentrates its legislative activity mainly in international trade and agriculture, whilst social policy is where the regions and the State (which is also the main actor in foreign policy) are more active. Third, at least two levels of government (in some cases all of them) are significantly involved in the legislative activity in many sectors, even where the rationale for that is, at best, very questionable, indicating that they actually share a larger number of policy tasks than that suggested by the economic theory. It appears therefore that an excessive number of competences are actually shared among different levels of government. From an economic perspective, it may well be recommended that some competences be shared, but only when the balance between scale or spillover effects and heterogeneity of preferences suggests so. When, on the contrary, too many levels of government are involved in a certain policy area, the distinction between their different responsibilities easily becomes unnecessarily blurred. This may not only leads to a slower and inefficient policy-making process, but also risks to make it too complicate to understand for citizens, who, on the contrary, should be able to know who is really responsible for a certain policy when they vote in national,local or European elections or in referenda on national or European constitutional issues.
Resumo:
The quality of astronomical sites is the first step to be considered to have the best performances from the telescopes. In particular, the efficiency of large telescopes in UV, IR, radio etc. is critically dependent on atmospheric transparency. It is well known that the random optical effects induced on the light propagation by turbulent atmosphere also limit telescope’s performances. Nowadays, clear appears the importance to correlate the main atmospheric physical parameters with the optical quality reachable by large aperture telescopes. The sky quality evaluation improved with the introduction of new techniques, new instrumentations and with the understanding of the link between the meteorological (or synoptical parameters and the observational conditions thanks to the application of the theories of electromagnetic waves propagation in turbulent medias: what we actually call astroclimatology. At the present the site campaigns are evolved and are performed using the classical scheme of optical seeing properties, meteorological parameters, sky transparency, sky darkness and cloudiness. New concept are added and are related to the geophysical properties such as seismicity, microseismicity, local variability of the climate, atmospheric conditions related to the ground optical turbulence and ground wind regimes, aerosol presence, use of satellite data. The purpose of this project is to provide reliable methods to analyze the atmospheric properties that affect ground-based optical astronomical observations and to correlate them with the main atmospheric parameters generating turbulence and affecting the photometric accuracy. The first part of the research concerns the analysis and interpretation of longand short-time scale meteorological data at two of the most important astronomical sites located in very different environments: the Paranal Observatory in the Atacama Desert (Chile), and the Observatorio del Roque de Los Muchachos(ORM) located in La Palma (Canary Islands, Spain). The optical properties of airborne dust at ORM have been investigated collecting outdoor data using a ground-based dust monitor. Because of its dryness, Paranal is a suitable observatory for near-IR observations, thus the extinction properties in the spectral range 1.00-2.30 um have been investigated using an empirical method. Furthermore, this PhD research has been developed using several turbulence profilers in the selection of the site for the European Extremely Large Telescope(E-ELT). During the campaigns the properties of the turbulence at different heights at Paranal and in the sites located in northern Chile and Argentina have been studied. This given the possibility to characterize the surface layer turbulence at Paranal and its connection with local meteorological conditions.
Resumo:
The present dissertation relates to methodologies and technics about industrial and mechanical design. The author intends to give a complete idea about the world of design, showing the theories of Quality Function Deployment and TRIZ, of other methods just like planning, budgeting, Value Analysis and Engineering, Concurrent Engineering, Design for Assembly and Manufactoring, etc., and their applications to five concrete cases. In these cases there are also illustrated design technics as CAD, CAS, CAM; Rendering, which are ways to transform an idea into reality. The most important object of the work is, however, the birth of a new methodology, coming up from a comparison between QFD and TRIZ and their integration through other methodologies, just like Time and Cost Analysis, learned and skilled during an important experience in a very famous Italian automotive factory.
Resumo:
In the last years of research, I focused my studies on different physiological problems. Together with my supervisors, I developed/improved different mathematical models in order to create valid tools useful for a better understanding of important clinical issues. The aim of all this work is to develop tools for learning and understanding cardiac and cerebrovascular physiology as well as pathology, generating research questions and developing clinical decision support systems useful for intensive care unit patients. I. ICP-model Designed for Medical Education We developed a comprehensive cerebral blood flow and intracranial pressure model to simulate and study the complex interactions in cerebrovascular dynamics caused by multiple simultaneous alterations, including normal and abnormal functional states of auto-regulation of the brain. Individual published equations (derived from prior animal and human studies) were implemented into a comprehensive simulation program. Included in the normal physiological modelling was: intracranial pressure, cerebral blood flow, blood pressure, and carbon dioxide (CO2) partial pressure. We also added external and pathological perturbations, such as head up position and intracranial haemorrhage. The model performed clinically realistically given inputs of published traumatized patients, and cases encountered by clinicians. The pulsatile nature of the output graphics was easy for clinicians to interpret. The manoeuvres simulated include changes of basic physiological inputs (e.g. blood pressure, central venous pressure, CO2 tension, head up position, and respiratory effects on vascular pressures) as well as pathological inputs (e.g. acute intracranial bleeding, and obstruction of cerebrospinal outflow). Based on the results, we believe the model would be useful to teach complex relationships of brain haemodynamics and study clinical research questions such as the optimal head-up position, the effects of intracranial haemorrhage on cerebral haemodynamics, as well as the best CO2 concentration to reach the optimal compromise between intracranial pressure and perfusion. We believe this model would be useful for both beginners and advanced learners. It could be used by practicing clinicians to model individual patients (entering the effects of needed clinical manipulations, and then running the model to test for optimal combinations of therapeutic manoeuvres). II. A Heterogeneous Cerebrovascular Mathematical Model Cerebrovascular pathologies are extremely complex, due to the multitude of factors acting simultaneously on cerebral haemodynamics. In this work, the mathematical model of cerebral haemodynamics and intracranial pressure dynamics, described in the point I, is extended to account for heterogeneity in cerebral blood flow. The model includes the Circle of Willis, six regional districts independently regulated by autoregulation and CO2 reactivity, distal cortical anastomoses, venous circulation, the cerebrospinal fluid circulation, and the intracranial pressure-volume relationship. Results agree with data in the literature and highlight the existence of a monotonic relationship between transient hyperemic response and the autoregulation gain. During unilateral internal carotid artery stenosis, local blood flow regulation is progressively lost in the ipsilateral territory with the presence of a steal phenomenon, while the anterior communicating artery plays the major role to redistribute the available blood flow. Conversely, distal collateral circulation plays a major role during unilateral occlusion of the middle cerebral artery. In conclusion, the model is able to reproduce several different pathological conditions characterized by heterogeneity in cerebrovascular haemodynamics and can not only explain generalized results in terms of physiological mechanisms involved, but also, by individualizing parameters, may represent a valuable tool to help with difficult clinical decisions. III. Effect of Cushing Response on Systemic Arterial Pressure. During cerebral hypoxic conditions, the sympathetic system causes an increase in arterial pressure (Cushing response), creating a link between the cerebral and the systemic circulation. This work investigates the complex relationships among cerebrovascular dynamics, intracranial pressure, Cushing response, and short-term systemic regulation, during plateau waves, by means of an original mathematical model. The model incorporates the pulsating heart, the pulmonary circulation and the systemic circulation, with an accurate description of the cerebral circulation and the intracranial pressure dynamics (same model as in the first paragraph). Various regulatory mechanisms are included: cerebral autoregulation, local blood flow control by oxygen (O2) and/or CO2 changes, sympathetic and vagal regulation of cardiovascular parameters by several reflex mechanisms (chemoreceptors, lung-stretch receptors, baroreceptors). The Cushing response has been described assuming a dramatic increase in sympathetic activity to vessels during a fall in brain O2 delivery. With this assumption, the model is able to simulate the cardiovascular effects experimentally observed when intracranial pressure is artificially elevated and maintained at constant level (arterial pressure increase and bradicardia). According to the model, these effects arise from the interaction between the Cushing response and the baroreflex response (secondary to arterial pressure increase). Then, patients with severe head injury have been simulated by reducing intracranial compliance and cerebrospinal fluid reabsorption. With these changes, oscillations with plateau waves developed. In these conditions, model results indicate that the Cushing response may have both positive effects, reducing the duration of the plateau phase via an increase in cerebral perfusion pressure, and negative effects, increasing the intracranial pressure plateau level, with a risk of greater compression of the cerebral vessels. This model may be of value to assist clinicians in finding the balance between clinical benefits of the Cushing response and its shortcomings. IV. Comprehensive Cardiopulmonary Simulation Model for the Analysis of Hypercapnic Respiratory Failure We developed a new comprehensive cardiopulmonary model that takes into account the mutual interactions between the cardiovascular and the respiratory systems along with their short-term regulatory mechanisms. The model includes the heart, systemic and pulmonary circulations, lung mechanics, gas exchange and transport equations, and cardio-ventilatory control. Results show good agreement with published patient data in case of normoxic and hyperoxic hypercapnia simulations. In particular, simulations predict a moderate increase in mean systemic arterial pressure and heart rate, with almost no change in cardiac output, paralleled by a relevant increase in minute ventilation, tidal volume and respiratory rate. The model can represent a valid tool for clinical practice and medical research, providing an alternative way to experience-based clinical decisions. In conclusion, models are not only capable of summarizing current knowledge, but also identifying missing knowledge. In the former case they can serve as training aids for teaching the operation of complex systems, especially if the model can be used to demonstrate the outcome of experiments. In the latter case they generate experiments to be performed to gather the missing data.
Resumo:
Over the last three decades, international agricultural trade has grown significantly. Technological advances in transportation logistics and storage have created opportunities to ship anything almost anywhere. Bilateral and multilateral trade agreements have also opened new pathways to an increasingly global market place. Yet, international agricultural trade is often constrained by differences in regulatory regimes. The impact of “regulatory asymmetry” is particularly acute for small and medium sized enterprises (SMEs) that lack resources and expertise to successfully operate in markets that have substantially different regulatory structures. As governments seek to encourage the development of SMEs, policy makers often confront the critical question of what ultimately motivates SME export behavior. Specifically, there is considerable interest in understanding how SMEs confront the challenges of regulatory asymmetry. Neoclassical models of the firm generally emphasize expected profit maximization under uncertainty, however these approaches do not adequately explain the entrepreneurial decision under regulatory asymmetry. Behavioral theories of the firm offer a far richer understanding of decision making by taking into account aspirations and adaptive performance in risky environments. This paper develops an analytical framework for decision making of a single agent. Considering risk, uncertainty and opportunity cost, the analysis focuses on the export behavior response of an SME in a situation of regulatory asymmetry. Drawing on the experience of fruit processor in Muzaffarpur, India, who must consider different regulatory environments when shipping fruit treated with sulfur dioxide, the study dissects the firm-level decision using @Risk, a Monte Carlo computational tool.
Resumo:
The dissertation contains five parts: An introduction, three major chapters, and a short conclusion. The First Chapter starts from a survey and discussion of the studies on corporate law and financial development literature. The commonly used methods in these cross-sectional analyses are biased as legal origins are no longer valid instruments. Hence, the model uncertainty becomes a salient problem. The Bayesian Model Averaging algorithm is applied to test the robustness of empirical results in Djankov et al. (2008). The analysis finds that their constructed legal index is not robustly correlated with most of the various stock market outcome variables. The second Chapter looks into the effects of minority shareholders protection in corporate governance regime on entrepreneurs' ex ante incentives to undertake IPO. Most of the current literature focuses on the beneficial part of minority shareholder protection on valuation, while overlooks its private costs on entrepreneur's control. As a result, the entrepreneur trade-offs the costs of monitoring with the benefits of cheap sources of finance when minority shareholder protection improves. The theoretical predictions are empirically tested using panel data and GMM-sys estimator. The third Chapter investigates the corporate law and corporate governance reform in China. The corporate law in China regards shareholder control as the means to the ends of pursuing the interests of stakeholders, which is inefficient. The Chapter combines the recent development of theories of the firm, i.e., the team production theory and the property rights theory, to solve such problem. The enlightened shareholder value, which emphasizes on the long term valuation of the firm, should be adopted as objectives of listed firms. In addition, a move from the mandatory division of power between shareholder meeting and board meeting to the default regime, is proposed.
Resumo:
The research is a 13-months ethnographic field work on the early operations of a Multi-party alliance active in the global field of indoor positioning. The study aims to understand and investigate empirically the challenges that at the individual and group level influence the organizing principle guiding the alliance operations and evolution. Its contribution rests on the dynamics affecting ecosystems of innovation and collaborative spaces of value co-creation in inter-organizational projects.