Nas últimas décadas do séc. XX, mais precisamente a partir do final da década de 80, uma questão fundamental começa a ser discutida multisetorialmente na Região Metropolitana de São Paulo (RMSP): Como lidar com as questões relacionadas à infra-estrutura urbana e aos limites do crescimento, considerando a necessidade de preservar o Cinturão Verde da RMSP? O objetivo principal desta dissertação de mestrado é descrever e analisar as ações coletivas e o movimento socioambiental, tomando como estudo de caso o movimento liderado por moradores do entorno da Cantareira que culminaram no reconhecimento internacional do Cinturão Verde da Cidade de São Paulo como Reserva da Biosfera pela UNESCO em 1994. Após mais de 20 anos de resistência, ainda hoje, este movimento persiste na forma de abaixo assinados, passeatas e ações judiciais, o que o transforma em uma das mais expressivas formas de ativismo ambiental em favor da preservação de uma floresta urbana. Ao traçarmos um panorama histórico, até os dias de hoje, das ações coletivas e do movimento ambiental em prol da Cantareira temos como objetivo investigar as razões pelas quais as populações urbanas participam de arenas políticas que decidem o futuro e a preservação de uma grande floresta dentro de uma cidade / In the last decades of the twentieth century, more precisely from the end of the decade of the eighties, a key issue started being discussed multisectorally in the Metropolitan Region of São Paulo (MASP): how to deal with the issues related to urban infrastructure and the limits of growth considering the need to maintain the green belt around the metropolitan region of São Paulo. The main objective of this master thesis is to describe and analyze the collective actions and the environmental movement taking as case study of the movement led by the Cantareira Park`s entour inhabitants, which resulted in the in international recognition of the Green Belt of the City of São Paulo as a Biosphere Reserve by UNESCO in 1994. After more than 20 years of resistence, still today, this movement continues in the form of undersigned, parades, lawsuits, which makes it one of the most expressive forms of environmental activism in favor of preserving an urban forest. When we draw a historical overview, until today, of collective action in environmental movement in favor of Cantareira, we have as objective to investigate the reasons for which the urban populations participate in policies that decide the future and the preservation of a great forest within a city

This thesis offers a comparative historical analysis of sub-state violent contention in Quebec and Corsica. It focuses specifically on the Front de Libération du Québec (FLQ) and the Fronte di Liberazione Naziunale Corsu (FLNC), in 1963 to 1971 and 1976 to 1990, respectively. The thesis argues that the FLQ and the FLNC sought to extend radical ideological space to promote independence in order to achieve revolutionary social and economic change through campaigns of violence and kidnappings. Theoretically, the thesis draws on the contentious politics and social movements literatures, which it notably combines with Radical Flank Effect (RFE). RFEs are interactive processes that aim to map the beneficial and/or detrimental impact of radical group action on moderate groups. Whilst commonly used to understand the political outcomes of social movements, RFE is used in this thesis in conjunction with social movement literature to compare the relationship between these violent movements and their more moderate opponents. To understand the internal dynamics of these movements, I have identified four key elements of contrast: membership, ideology, network structure and strategy. I draw on, for example, McAdam, Tarrow and Tilly's (2001) mobilization method, which aids an understanding of membership and ideology by framing the interaction amongst challengers, their opponents and the media. This thesis seeks to understand FLQ and FLNC mobilization in light of the aim to shape and develop radical ideological space in the sub-states of Quebec and Corsica. It draws on an extensive study of archival data that includes police reports that have only recently been made available in Canada, transcripts of court cases, newspapers, and an interview with a former member of the FLNC, as well as secondary sources. The central orienting question is: what explains the contrasting patterns of sub-state violent contention in Quebec and Corsica? More specifically, why did the FLQ dissolve in 1971, yet the FLNC continued its violent trajectory, albeit less political and nationalist, until 2014? The FLQ and the FLNC differently subscribed to Marxism and postcolonialism. The FLQ was committed to a Marxist program of revolutionary change, and this commitment was shared by the FLNC until the collapse of communism in central and Eastern Europe in 1989. FLQ members considered themselves 'urban revolutionaries' and employed Marxism to understand the economic disparity in industrial Montreal. Early Corsican violent contention, in contrast, included Maoist influences, in particular, through their demand for agrarian reform. The two groups viewed the relationship between their sub-states (Quebec and Corsica) and central states (Canada and France) through a colonial lens, and understood their mobilization against these states and elite minorities (the Anglophone elite in Quebec and the pieds noirs in Corsica) in this light. Both violent movements targeted this colonial relationship. Both the FLQ and FLNC manifestos were economically and politically focused, land and culture were additionally highlighted by the FLNC. This thesis found that sub-state violent contention in the very different contexts of Quebec and Corsica shared an overall pattern, an arc of violent mobilization. The initial mobilization developed from a frustration with moderate political groups; radicalization grew and new tactics were embraced; until turning points that included the assassination of Pierre Laporte by the FLQ and the division of the FLNC into competitive factions, and then a decline of activity, mobilization and recruitment. Although the FLQ and the FLNC contrasted greatly in terms of membership, ideology, organization and strategy, both groups attempted to extend radical space through the use of violent contention in these two very different nations. Ultimately, however, while the FLQ and the FLNC were able to extend or maintain radical space at times, yet they failed to sustain the extension of ideological radical space on the basis on their revolutionary manifestos.

We introduce abortable and query-abortable object types intended for implementation in asynchronous shared-memory systems with low contention. Implementations of such types behave like ordinary objects when accessed sequentially, but may abort operations when accessed concurrently. An aborted operation may or may not take effect, i.e., cause a state transition, and it returns no indication of which possibility occurred. Since this uncertainty can be problematic, a query-abortable type supports a QUERY operation that each process can use to determine its last non-QUERY operation on the object that caused a state transition, and the response associated with this state transition. Our research is closely related to obstruction-free implementations (introduced by Herlihy, Luchangco and Moir) and responsive obstruction-free implementations (introduced by Attiya, Guerraoui and Kouznetsov). Like abortable and query-abortable types, these implementations may exhibit degraded behaviour in the face of contention. We show that abortable registers--registers strictly weaker than safe registers--can be used to obtain obstruction-free and responsive obstruction-free implementations for any type. We present universal constructions for abortable and query-abortable types that are novel and efficient in the number of registers used. Specifically, they are based on a simple timestamping mechanism for detecting concurrent executions, and, in systems with n processes, use only n abortable registers or only O(n^2) single-reader, single-writer abortable registers. The timestamping mechanism we introduce is based on the inc&read counter type and appears to be interesting in its own right. As a generalization, we study the k-inc&read counter types, for k>0. We also identify a potential problem with correctness properties based on step contention: with such properties, the composition of correct object implementations may result in an implementation that is not correct. In other words, implementations defined in terms of step contention are not always composable. To avoid this problem, we introduce a property based on interval contention, namely non-triviality, to define the correct behaviour of abortable and query-abortable object implementations.

We introduce abortable and query-abortable object types intended for implementation in asynchronous shared-memory systems with low contention. Implementations of such types behave like ordinary objects when accessed sequentially, but may abort operations when accessed concurrently. An aborted operation may or may not take effect, i.e., cause a state transition, and it returns no indication of which possibility occurred. Since this uncertainty can be problematic, a query-abortable type supports a QUERY operation that each process can use to determine its last non-QUERY operation on the object that caused a state transition, and the response associated with this state transition. Our research is closely related to obstruction-free implementations (introduced by Herlihy, Luchangco and Moir) and responsive obstruction-free implementations (introduced by Attiya, Guerraoui and Kouznetsov). Like abortable and query-abortable types, these implementations may exhibit degraded behaviour in the face of contention. We show that abortable registers--registers strictly weaker than safe registers--can be used to obtain obstruction-free and responsive obstruction-free implementations for any type. We present universal constructions for abortable and query-abortable types that are novel and efficient in the number of registers used. Specifically, they are based on a simple timestamping mechanism for detecting concurrent executions, and, in systems with n processes, use only n abortable registers or only O(n^2) single-reader, single-writer abortable registers. The timestamping mechanism we introduce is based on the inc&read counter type and appears to be interesting in its own right. As a generalization, we study the k-inc&read counter types, for k>0. We also identify a potential problem with correctness properties based on step contention: with such properties, the composition of correct object implementations may result in an implementation that is not correct. In other words, implementations defined in terms of step contention are not always composable. To avoid this problem, we introduce a property based on interval contention, namely non-triviality, to define the correct behaviour of abortable and query-abortable object implementations.

Transactional memory systems are expected to enable parallel programming at lower programming complexity, while delivering improved performance over traditional lock-based systems. Nonetheless, there are certain situations where transactional memory systems could actually perform worse. Transactional memory systems can outperform locks only when the executing workloads contain sufficient parallelism. When the workload lacks inherent parallelism, launching excessive transactions can adversely degrade performance. These situations will actually become dominant in future workloads when large-scale transactions are frequently executed. In this thesis, we propose a new paradigm called adaptive transaction scheduling to address this issue. Based on the parallelism feedback from applications, our adaptive transaction scheduler dynamically dispatches and controls the number of concurrently executing transactions. In our case study, we show that our low-cost mechanism not only guarantees that hardware transactional memory systems perform no worse than a single global lock, but also significantly improves performance for both hardware and software transactional memory systems.

Nas últimas décadas do séc. XX, mais precisamente a partir do final da década de 80, uma questão fundamental começa a ser discutida multisetorialmente na Região Metropolitana de São Paulo (RMSP): Como lidar com as questões relacionadas à infra-estrutura urbana e aos limites do crescimento, considerando a necessidade de preservar o Cinturão Verde da RMSP? O objetivo principal desta dissertação de mestrado é descrever e analisar as ações coletivas e o movimento socioambiental, tomando como estudo de caso o movimento liderado por moradores do entorno da Cantareira que culminaram no reconhecimento internacional do Cinturão Verde da Cidade de São Paulo como Reserva da Biosfera pela UNESCO em 1994. Após mais de 20 anos de resistência, ainda hoje, este movimento persiste na forma de abaixo assinados, passeatas e ações judiciais, o que o transforma em uma das mais expressivas formas de ativismo ambiental em favor da preservação de uma floresta urbana. Ao traçarmos um panorama histórico, até os dias de hoje, das ações coletivas e do movimento ambiental em prol da Cantareira temos como objetivo investigar as razões pelas quais as populações urbanas participam de arenas políticas que decidem o futuro e a preservação de uma grande floresta dentro de uma cidade / In the last decades of the twentieth century, more precisely from the end of the decade of the eighties, a key issue started being discussed multisectorally in the Metropolitan Region of São Paulo (MASP): how to deal with the issues related to urban infrastructure and the limits of growth considering the need to maintain the green belt around the metropolitan region of São Paulo. The main objective of this master thesis is to describe and analyze the collective actions and the environmental movement taking as case study of the movement led by the Cantareira Park`s entour inhabitants, which resulted in the in international recognition of the Green Belt of the City of São Paulo as a Biosphere Reserve by UNESCO in 1994. After more than 20 years of resistence, still today, this movement continues in the form of undersigned, parades, lawsuits, which makes it one of the most expressive forms of environmental activism in favor of preserving an urban forest. When we draw a historical overview, until today, of collective action in environmental movement in favor of Cantareira, we have as objective to investigate the reasons for which the urban populations participate in policies that decide the future and the preservation of a great forest within a city

No description available.

Yes / The only available solution in the IEEE 802.22 standard for avoiding collision amongst various contending customer premises equipment (CPEs) attempting to associate with a base station (BS) is binary exponential random backoff process in which the contending CPEs retransmit their association requests. The number of attempts the CPEs send their requests to the BS are fixed in an IEEE 802.22 network. This paper presents a mathematical framework that helps the BS in determining at which attempt the majority of the CPEs become part of the wireless regional area network from a particular number of contending CPEs. Based on a particular attempt, the ranging request collision probability for any number of contending CPEs with respect to contention window size is approximated. The numerical results validate the effectiveness of the approximation. Moreover, the average ranging success delay experienced by the majority of the CPEs is also determined.

The parallel nature of process execution on Chip Multi-Processors (CMPs) has boosted levels of application performance far beyond the capabilities of erstwhile single-core designs. Generally, CMPs offer improved performance by integrating multiple simpler cores onto a single die that share certain computing resources among them such as last-level caches, data buses, and main memory. This ensures architectural simplicity while also boosting performance for multi-threaded applications. However, a major trade-off associated with this approach is that concurrently executing applications incur performance degradation if their collective resource requirements exceed the total amount of resources available to the system. If dynamic resource allocation is not carefully considered, the potential performance gain from having multiple cores may be outweighed by the losses due to contention for allocation of shared resources. Additionally, CMPs with inbuilt dynamic voltage-frequency scaling (DVFS) mechanisms may try to compensate for the performance bottleneck by scaling to higher clock frequencies. For performance degradation due to shared-resource contention, this does not necessarily improve performance but does ensure a significant penalty on power consumption due to the quadratic relation of electrical power and voltage (P_dynamic ∝ V^2 * f).This dissertation presents novel methodologies for balancing the competing requirements of high performance, fairness of execution, and enforcement of priority, while also ensuring overall power efficiency of CMPs. Specifically, we (1) Analyze the problem of resource interference during concurrent process execution and propose two fine-grained scheduling methodologies for improving overall performance and fairness, (2) Develop an approach for enforcement of priority (i.e., minimum performance) for specific processes while avoiding resource starvation for others, and (3) Present a machine-learning approach for maximizing the power efficiency (performance-per-Watt) of CMPs through estimation of a workload's performance and power consumption limits at different clock frequencies.As modern computing workloads become increasingly dynamic, and computers themselves become increasingly ubiquitous, the problem of finding the ideal balance between performance and power consumption of CMPs is of particular relevance today, especially given the unprecedented proliferation of embedded devices for use in Internet-of-Things, edge computing, smart wearables, and even exotic experiments such as space probes comprised entirely of a CMP, sensors, and an antenna ("space chips"). Additionally, reducing power consumption while maintaining constant performance can contribute to addressing the growing problem of dark silicon.

Cette thèse analyse la possibilité d'utiliser des communications sans fil inter-véhiculaires pour améliorer la sécurité routière. Les performances du nouveau réseau ainsi créé (réseau ad-hoc véhiculaire) sont étudiées analytiquement et par des simulations dans un environnement réaliste. La thèse se concentre surtout sur des scénarios avec une forte densité de véhicules. Dans ce cas, l'accès au support devient un problème essentiel, en principal pour les applications de sécurité routière qui nécessitent une qualité de service élevée pour fonctionner dans un tel contexte. Ce travail montre que la version actuelle du standard IEEE 802.11, proposé comme méthode d'accès dans les réseaux véhiculaires, ne peut pas résoudre ce problème de passage à l'échelle pour supporter correctement les applications de sécurité routière. Plusieurs améliorations possibles sont analysées, liées à l'utilisation optimale de certains paramètres du protocole comme la taille de la fenêtre de contention ou bien le seuil de détection de la porteuse. Des nouveaux mécanismes adaptatifs visant ces paramètres sont proposés et les améliorations ainsi obtenues sont non-négligeables. Finalement, une nouvelle méthode d'accès est définie, en tenant compte des caractéristiques des applications de sécurité routière. Toujours basée sur des techniques CSMA, cette technique donne des résultats largement supérieurs à la version standard actuelle. / The equipment of vehicles with wireless communication devices in order to improve road safety is a major component of a future intelligent transportation system. The success and availability of IEEE 802.11-based products make this technology the main competitor for the Medium Access Control (MAC) layer used in vehicle-to-vehicle communication. The IEEE 802.11p amendment has been specially designed in this special context of wireless access in vehicular environments. However, as all the other approaches based on Carrier Sense Multiple Access (CSMA), this protocol presents scalability problems, which leads to poor performance in high density scenarios, quite frequent in the case of a vehicular ad hoc network (VANET). This thesis studies the congestion control problem in the context of safety vehicular communications, with a special focus on the back-off mechanism and the carrier sense function. First of all, a number of important characteristics presented by the safety messages are discovered and understood by the means of an analytical framework. Second, the lessons learned from the analytical study are put into practice with the design of two adaptive mechanisms (one for the contention window and the other one for the carrier sense threshold) that take into account the local vehicular density. These mechanisms remain simple, but highly efficient, while also being straightforward to integrate in IEEE 802.11 devices. Finally, by taking into account the most important properties of a safety VANET, a new CSMA-based MAC protocol is proposed. This new access method, named Safety Range CSMA (SR-CSMA), relies on the idea that collisions can not be avoided in a high density network. However, by increasing the number of simultaneous transmissions between geographically distant nodes, SR-CSMA manages to better protect the immediate neighborhood, the most important area for safety applications.