Macroscopic quantum tunneling in a dc SQUID: Instanton splitting

The theory of macroscopic quantum tunneling is applied to a current-biased dc SQUID which constitutes a system of two interacting quantum degrees of freedom coupled to the environment. The decay probability is obtained in the exponential approximation for the overdamped case. Close to the critical driving force of the system, the decay of the metastable state is determined by a unique instanton solution describing the symmetric decay of the phases in each of the two Josephson juctions. Upon reducing the external driving force a new regime is reached where the instanton splits. The doubling of the decay channels reduces the decreasing of the decay rate in the quantum regime. A current-temperature phase diagram is constructed based on the Landau theory of phase transitions. Depending on the external parameters the system develops either a first- or a second-order transition to the split-instanton regime. © 1994 The American Physical Society.

Structural and geochronological studies of the Médio Coreaú domain, NE Brazil: Constraints on Brasiliano/Pan-African tectonic evolution in the NW part of the Borborema Province

Recent structural investigations and geochronological studies of rocks from the Médio Coreaú domain in the NW part of northeast Brazil's Borborema Province provide important constraints on the tectonic evolution of the region both preceeding and during the assembly of West Gondwana. Field observations of structural features and fabrics have revealed the presence of four distinct deformational phases in the MCD: D1, D2, D3 and D4. Only the early Paleoproterozoic gneisses record the D1 tectonic event and its preservation is cryptic owing to strong overprinting by the subsequent tectonic phases. The D2, D3 and D4 events affected younger supracrustal rocks and Neoproterzoic magmatic units, and U-Pb geochronological constraints show that all of these tectonic phases represent deformational events that occurred during Brasiliano collision between the West African craton and the NW part of the Borborema Province. The D2 phase, lasting between ca. 622 and 591 Ma, represents a frontal collision stage, which generated NW verging thrust-nappe systems, low-angle foliation, high-grade metamorphism and crustal anatexis. Transition to a strike-slip regime (D3) occurred at around 591 Ma when the region entered a phase of escape tectonics. During this time, the motion of crustal blocks towards NE and E was accommodated along numerous anastomosing shear zones. Syntectonic emplacement of granitoid plutons took place in transtensional domains of the shear zone system. The intrusion of late tectonic granitoids and rapid uplift and cooling of the orogen around 560 Ma as a result of D4 transpressional movements marked the end of the D3 transcurrent regime. These findings show that only the early Paleoproterozoic gneisses in the Médio Coreaú domain are polycyclic in nature. Rather than representing distinct orogenic events, the D2, D3 and D4 tectonic phases are a manifestation of progressive deformational events that developed in response to changes in the regional stress field during convergence and collision between the Borborema Province and its surrounding cratons.

Respiratory chemoreceptor function in vertebrates - Comparative and evolutionary aspects

The sensing of blood gas tensions and/or pH is an evolutionarily conserved, homeostatic mechanism, observable in almost all species studied from invertebrates to man. In vertebrates, a shift from the peripheral O2-oriented sensing in fish, to the central CO2/pH sensing in most tetrapods reflects the specific behavioral requirements of these two groups whereby, in teleost fish, a highly O2-oriented control of breathing matches the ever-changing and low oxygen levels in water, whilst the transition to air-breathing increased the importance of acid-base regulation and O2-related drive, although retained, became relatively less important. The South American lungfish and tetrapods are probably sister groups, a conclusion backed up by many similar features of respiratory control. For example, the relative roles of peripheral and central chemoreceptors are present both in the lungfish and in land vertebrates. In both groups, the central CO2/pH receptors dominate the ventilatory response to hypercarbia (60-80), while the peripheral CO2/pH receptors account for 20-30. Some basic components of respiratory control have changed little during evolution. This review presents studies that reflect the current trends in the field of chemoreceptor function, and several laboratories are involved. An exhaustive review on the previous literature, however, is beyond the intended scope of the article. Rather, we present examples of current trends in respiratory function in vertebrates, ranging from fish to humans, and focus on both O2 sensing and CO2 sensing. As well, we consider the impact of chronic levels of hypoxia - a physiological condition in fish and in land vertebrates resident at high elevations or suffering from one of the many cardiorespiratory disease states that predispose an animal to impaired ventilation or cardiac output. This provides a basis for a comparative physiology that is informative about the evolution of respiratory functions in vertebrates and about human disease. Currently, most detail is known for mammals, for which molecular biology and respiratory physiology have combined in the discovery of the mechanisms underlying the responses of respiratory chemoreceptors. Our review includes new data on nonmammalian vertebrates, which stresses that some chemoreceptor sites are of ancient origin.

Preliminary Overview of the Economies of Latin America and the Caribbean 2007

Includes bibliography

Social Panorama of Latin America 2011

Includes bibliography

Financing for sustainable development: visions and proposals for action from a Latin American and Caribbean perspective

Foreword Throughout the preparatory process for the World Summit on Sustainable Development and at the Summit itself, which was held in Johannesburg, South Africa, from 26 August to 4 September 2002, discussions were dominated by one central concern: the need to define and reach consensus on concrete, quantitative goals, with fixed deadlines for implementation, which were to supplement the Millennium Development Goals and facilitate progress towards an effective transition to sustainable development. Participants at the Summit explicitly affirmed the need, as a matter of urgency, to identify the financial and technical resources whereby sustainable development would become a reality and benefit directly and particularly rural and urban communities in the developing countries. The document we are now presenting is the outcome of extensive discussions held at a high-level forum during the Johannesburg Summit. Led by representatives of the Government of Mexico, the Economic Commission for Latin America and the Caribbean (ECLAC), the United Nations Development Programme (UNDP) and the Andean Development Corporation, those discussions were based on the ECLAC/UNDP study entitled Financing for sustainable development in Latin America and the Caribbean: from Monterrey to Johannesburg, which considers the opportunities and challenges for improving prospects for investment and financing for sustainable development and underscores the need to establish a new balance between the market economy and public interest through joint public/private initiatives that combine market innovation, social responsibility and appropriate regulations. Other eminent persons attending the event included heads of State, such as Gustavo Noboa, then President of Ecuador; Enrique V. Iglesias, President of the Inter-American Development Bank (IDB); José María Figueres, Managing Director of the Global Agenda of the World Economic Forum and former President of Costa Rica; and Gro Harlem Brundtland, the legendary figure who pioneered sustainable development. Valuable contributions to the discussions were made by Yolanda Kakabadse, President of the World Conservation Union; Xóchitl Gálvez Ruiz, head of the Unit for the Development of Indigenous Peoples of the Office of the President of Mexico; Cecilia López, former Minister for the Environment of Colombia; and Juan Carlos Maqueda, then Vice President of Argentina. The views emerging from the forum as set forth in this document are designed to facilitate and promote application of the Plan of Implementation of the World Summit on Sustainable Development within the framework of the Millennium Development Goals and the commitments assumed at the International Conference on Financing for Development, which was held in Monterrey, Mexico. We also aspire to continue moving forward with the adoption of measures and policies to increase investment and financing for sustainable development as well as to foster partnerships between the public and private sectors and nongovernmental organizations. We recognize, in this context, the importance of strengthening and improving public and private institutions in order to meet the operational needs associated with the effort to achieve the Millennium Development Goals and pursue the Plan of Implementation formulated in Johannesburg. We trust that this document will contribute to in-depth discussions on the application of the Plan of Implementation in the relevant forums, in particular the United Nations Commission on Sustainable Development. The Plan of Implementation of the World Summit on Sustainable Development opens up new opportunities for Latin America and the Caribbean to renew and revive their own regional agenda -with emphasis on global and especially regional public goods- and to interweave it more cohesively with the global agenda in order to promote the common interests of Latin America and the Caribbean more forcefully in international development forums. The regional agenda and the global agenda cannot be separated in a contrived manner; indeed, to an increasing degree, what we are witnessing are global environmental processes which call for action at the local level. The achievement of sustainable development in Latin America and the Caribbean, where the necessary economic, social, environmental and geopolitical conditions are combined, requires a subtle balance between the market economy, the State and the citizen. Such a balance will result in the consolidation of democratic governance in the service of human development. VICENTE FOX President of Mexico JOSÉ ANTONIO OCAMPO Executive Secretary, Economic Commission for Latin America and the Caribbean (ECLAC) ELENA MARTÍNEZ Assistant Aministrator and Regional Director for Latin America and the Caribbean of the United Nations Development Programme (UNDP) ENRIQUE GARCÍA Executive President, Andean Development Corporation (ADC)""

Road maps towards an information society in Latin America and the Caribbean

Includes bibliography

Building an information society: a Latin American and Caribbean perspective

Includes bibliography

Structural change and productivity growth, 20 years later: old problems, new opportunities

Includes bibliography

Latin America on its path into the digital age: where are we?

Includes bibliography

Theory and practice of industrial policy: evidence from the Latin American experience

Includes bibliography

Innovation and technology policy (ITP) for catching up: a three phase life cycle framework for industrializing economies

Includes bibliography

Pension reform in Europe in the 90's and lessons for Latin America

Includes bibliography

Market failure and technological policy

Includes bibliography

The ongoing history of a Chilean metal products and machinery firm

Includes bibliography