Non-zero torsion and late cosmology

In this work, we study some thermodynamical aspects associated with torsion in a flat FLRW spacetime cosmic evolution. By implementing two Ansatze for the torsion term, we find that the model admits a phantom regime or a quintessence behavior. This scheme differs from the $\Lambda$CDM model at the thermodynamical level. The resulting cosmic expansion is not adiabatic, the fulfillment of the second law of thermodynamics requires a positive torsion term, and the temperature of the cosmic fluid is always positive. The entropy of the torsion phantom scenario is negative, but introducing chemical potential solves this issue. For a Dirac-Milne type Universe, the torsion leads to a growing behavior for the temperature of the fluid but has no incidence on the rate of expansion.Comment: 20 pages, 1 figure. Accepted version in EPJ

Building global and scalable systems with atomic multicast

The rise of worldwide Internet-scale services demands large distributed systems. Indeed, when handling several millions of users, it is common to operate thousands of servers spread across the globe. Here, replication plays a central role, as it contributes to improve the user experience by hiding failures and by providing acceptable latency. In this thesis, we claim that atomic multicast, with strong and well-defined properties, is the appropriate abstraction to efficiently design and implement globally scalable distributed systems. Internet-scale services rely on data partitioning and replication to provide scalable performance and high availability. Moreover, to reduce user-perceived response times and tolerate disasters (i.e., the failure of a whole datacenter), services are increasingly becoming geographically distributed. Data partitioning and replication, combined with local and geographical distribution, introduce daunting challenges, including the need to carefully order requests among replicas and partitions. One way to tackle this problem is to use group communication primitives that encapsulate order requirements. While replication is a common technique used to design such reliable distributed systems, to cope with the requirements of modern cloud based ``always-on'' applications, replication protocols must additionally allow for throughput scalability and dynamic reconfiguration, that is, on-demand replacement or provisioning of system resources. We propose a dynamic atomic multicast protocol which fulfills these requirements. It allows to dynamically add and remove resources to an online replicated state machine and to recover crashed processes. Major efforts have been spent in recent years to improve the performance, scalability and reliability of distributed systems. In order to hide the complexity of designing distributed applications, many proposals provide efficient high-level communication abstractions. Since the implementation of a production-ready system based on this abstraction is still a major task, we further propose to expose our protocol to developers in the form of distributed data structures. B-trees for example, are commonly used in different kinds of applications, including database indexes or file systems. Providing a distributed, fault-tolerant and scalable data structure would help developers to integrate their applications in a distribution transparent manner. This work describes how to build reliable and scalable distributed systems based on atomic multicast and demonstrates their capabilities by an implementation of a distributed ordered map that supports dynamic re-partitioning and fast recovery. To substantiate our claim, we ported an existing SQL database atop of our distributed lock-free data structure. Here, replication plays a central role, as it contributes to improve the user experience by hiding failures and by providing acceptable latency. In this thesis, we claim that atomic multicast, with strong and well-defined properties, is the appropriate abstraction to efficiently design and implement globally scalable distributed systems. Internet-scale services rely on data partitioning and replication to provide scalable performance and high availability. Moreover, to reduce user-perceived response times and tolerate disasters (i.e., the failure of a whole datacenter), services are increasingly becoming geographically distributed. Data partitioning and replication, combined with local and geographical distribution, introduce daunting challenges, including the need to carefully order requests among replicas and partitions. One way to tackle this problem is to use group communication primitives that encapsulate order requirements. While replication is a common technique used to design such reliable distributed systems, to cope with the requirements of modern cloud based ``always-on'' applications, replication protocols must additionally allow for throughput scalability and dynamic reconfiguration, that is, on-demand replacement or provisioning of system resources. We propose a dynamic atomic multicast protocol which fulfills these requirements. It allows to dynamically add and remove resources to an online replicated state machine and to recover crashed processes. Major efforts have been spent in recent years to improve the performance, scalability and reliability of distributed systems. In order to hide the complexity of designing distributed applications, many proposals provide efficient high-level communication abstractions. Since the implementation of a production-ready system based on this abstraction is still a major task, we further propose to expose our protocol to developers in the form of distributed data structures. B- trees for example, are commonly used in different kinds of applications, including database indexes or file systems. Providing a distributed, fault-tolerant and scalable data structure would help developers to integrate their applications in a distribution transparent manner. This work describes how to build reliable and scalable distributed systems based on atomic multicast and demonstrates their capabilities by an implementation of a distributed ordered map that supports dynamic re-partitioning and fast recovery. To substantiate our claim, we ported an existing SQL database atop of our distributed lock-free data structure

O progresso do conhecimento e o desenvolvimento cultural em Leonardo Coimbra e Bernard Lonergan

Leonardo Coimbra y Bernard Lonergan dialogan con Lucien Lévy-Bruhl en el contexto de sus reflexiones acerca del progreso del conocimiento y del desarrollo cultural. Lonergan divide la evolución histórica de la conciencia humana en cuatro estadíos de desarrollo: sentido común indiferenciado, sentido común dififerenciado, consciencia diferenciada y consciencia histórica. Leonardo Coimbra divide el desarrollo del pensamiento humano en tres grandes periodos: razón mítica, razón formal abstracta y razón experimental. Los dos autores consideran que hay una ascensión del pensamiento del nivel prelógico de la mítica conciencia indiferenciada, a un nivel lógico de la razón conceptual y analítica y de la razón experimental científica.Leonardo Coimbra and Bernard Lonergan Dialogue with Lucien Lévy-Bruhl in the context of their reflections on the progress of knowledge and culture development. Lonergan divide the historical evolution of human consciousness into four states of development: undifferentiated common sense, common sense differentiated, differentiated consciousness and historical consciousness. In turn, Leonardo Coimbra divides the development of human thinking into three main periods: mythical reason, Formal experimental abstract reason and reason. The two authors consider that there is an advance in thinking from the pre-logic level of undifferentiated mythical consciousness to the logical level of conceptual and analytical reason and onto the level of experimental scientific reason.Leonardo Coimbra e Bernard Lonergan dialogam com Lucien Lévy-Bruhl no contexto das suas reflexões acerca do progresso do conhecimento e do desenvolvimento cultural. Lonergan divide a evolução histórica da consciência humana em quatro estádios de desenvolvimento: senso comum indiferenciado, senso comum diferenciado, consciência diferenciada e consciência histórica. Leonardo Coimbra divide o desenvolvimento do pensamento humano em três grandes períodos: razão mítica, razão formal abstrata e razão experimental. Os dois autores consideram que há uma ascensão do pensamento do nível pré-lógico da mítica consciência indiferenciada para o nível lógico da razão conceptual e analítica e da razão experimental científica.peerReviewe

A ressurreição pessoal e a espiritualização do Universo na filosofia escatológica "Del sentimiento trágico de la vida" de Miguel de Unamuno

Miguel de Unamuno cree que el final del universo será espiritual. La vida encierra un movimiento redentor que culminará en la salvación de toda la humanidad en el sentido de la apocatastase paulina de Orígenes. Esto no sólo se interrelacionan con la inmortalidad del alma en el sentido platónico, sino también con la resurrección del cuerpo en el sentido cristiano. La vida después de la muerte no consta de ninguna dilución en las conciencias de Dios sino en una relación personal con la conciencia de Dios y con todas las otras conciencias. Este futuro Paraiso consiste en la espiritualización de toda la creación en el ámbito de la garantía de la identidad individual de cada ser humano.Miguel de Unamuno believes the end of the Universe will be spiritualized. Life encloses a redemptive movement that shall culminate in the salvation of all of humanity in the apocatastasic sense heralded by Paul of Orígenes. This does not only interrelate with the immortality of the soul in the Platonic sense but also with the resurrection of the body in the Christian sense. Life beyond death does not consist of any dilution into the consciousnesses of God but instead in a personal relationship with God-Consciousness and with all the other consciousnesses. This future paradise consists of the spiritualization of all of creation within the scope of guaranteeing the individual identity of each being.Miguel de Unamuno acredita que no fim todo o Universo será espiritualizado. A vida encerra um movimento redentor, que culminará com a salvação de toda a humanidade, no sentido enunciado pela apocatástase paulina de Orígenes. Não se trata apenas da imortalidade da alma, no sentido platónico, mas sim da ressurreição do corpo, no sentido cristão. A vida para além da morte não consiste numa diluição das consciencias em Deus, mas sim numa relação pessoal com Deus-Consciência e com todas as outras consciências. O paraíso futuro consiste na espiritualização de toda a criação, em que será garantida a identidade individual de cada ser.peerReviewe

On The Evolution of TFP in Latin America (revised)

Due to several policy distortions, including import-substitution industrialization, widespread government intervention and both domestic and international competitive barriers, there has been a general presumption that Latin America has been much less productive than the leading economies in the last decades. In this paper we show, however, that until the late seventies Latin American countries had high productivity levels relative to the United States. It is only after the late seventies that we observe a fast decrease of relative TFP in Latin America. We also show that the inclusion of human capital in the production function makes a crucial di¤erence in the TFP calculations for Latin America.