New Permo-Carboniferous geochemical data from central Thailand: implication for a volcanic arc model

Current ideas and models of geotectonic reconstructions of Southeast Asia are reviewed and new data on Late Carboniferous through Middle Permian tuffites and sills from central Thailand are presented in the light of the problems of Southeast Asian palaeogeography. The volcanic rocks of quartz-keratophyric to spilitic composition are associated with platform carbonates and deep basin sediments. Their geochemistry and the character of the accompanying sediments suggest the existence of a Late Palaeozoic volcanic arc separating a subduction zone in the west from a back arc basin to the east. The geotectonic frame of Southeast Asia is explained in terms of repeated accretion of volcanic arcs by the Late Palaeozoic subduction zone along the northern Tethys margin

Sub-kHz-level relative stabilization of an intracavity doubled continuous wave optical parametric oscillator using Pound-Drever-Hall scheme

We report the relative frequency stabilization of an intracavity frequency doubled singly resonant optical parametric oscillator on a Fabry-Perot\'etalon. The red/orange radiation produced by the frequency doubling of the intracavity resonant idler is stabilized using the Pound-Drever-Hall locking technique. The relative frequency noise of this orange light, when integrated from 1 Hz to 50 kHz, corresponds to a standard deviation of 700 Hz. The frequency noise of the pump laser is shown experimentally to be transferred to the non resonant signal beam

Laser cooling of trapped ytterbium ions with an ultraviolet diode laser

We demonstrate an ultraviolet diode laser system for cooling of trapped ytterbium ions. The laser power and linewidth are comparable to previous systems based on resonant frequency doubling, but the system is simpler, more robust, and less expensive. We use the laser system to cool small numbers of ytterbium ions confined in a linear Paul trap. From the observed spectra, we deduce final temperatures < 270 mK.Comment: submitted to Opt. Let

The optical calcium frequency standards of PTB and NIST

We describe the current status of the Ca optical frequency standards with laser-cooled neutral atoms realized in two different laboratories for the purpose of developing a possible future optical atomic clock. Frequency measurements performed at the Physikalisch-Technische Bundesanstalt (PTB) and the National Institute of Standards and Technology (NIST) make the frequency of the clock transition of 40Ca one of the best known optical frequencies (relative uncertainty 1.2e-14) and the measurements of this frequency in both laboratories agree to well within their respective uncertainties. Prospects for improvement by orders of magnitude in the relative uncertainty of the standard look feasible.Comment: 13 pages, 11 figures, to appear in Comptes Rendus Physiqu

Trapping of single atoms in cavity QED

By integrating the techniques of laser cooling and trapping with those of cavity quantum electrodynamics (QED), single Cesium atoms have been trapped within the mode of a small, high finesse optical cavity in a regime of strong coupling. The observed lifetime for individual atoms trapped within the cavity mode is $\tau \approx 28$ms, and is limited by fluctuations of light forces arising from the far-detuned intracavity field. This initial realization of trapped atoms in cavity QED should enable diverse protocols in quantum information science.Comment: 4 pages, 4 figure

Ultra-cold atoms in an optical cavity: two-mode laser locking to the cavity avoiding radiation pressure

The combination of ultra-cold atomic clouds with the light fields of optical cavities provides a powerful model system for the development of new types of laser cooling and for studying cooperative phenomena. These experiments critically depend on the precise tuning of an incident pump laser with respect to a cavity resonance. Here, we present a simple and reliable experimental tuning scheme based on a two-mode laser spectrometer. The scheme uses a first laser for probing higher-order transversal modes of the cavity having an intensity minimum near the cavity's optical axis, where the atoms are confined by a magnetic trap. In this way the cavity resonance is observed without exposing the atoms to unwanted radiation pressure. A second laser, which is phase-locked to the first one and tuned close to a fundamental cavity mode drives the coherent atom-field dynamics.Comment: 7 pages, 7 figure

Replace One´s Place: The Livelihood of Internally Displaced People in Colombia

Colombia es el país con el número más alto en desplazados internos en el mundo. La población rural huye generalmente por la violencia generada en el conflicto armado. Pero también los llamados “proyectos de desarrollo” de empresas multinacionales que invierten en infraestructura generalmente afectan a comunidades locales. El Banco Mundial ofrece un manual de operaciones (4.12) para los “reasentamientos inducidos por el desarrollo” para evitar el empobrecimiento. El manual pone énfasis en la devolución de los bienes desubsistencia (livelihood) de la población reasentada. Pero, ¿comparte la población afectada por desplazamiento el mismo concepto de subsistencia (livelihood)? ¿Se puede reemplazar el lugar (place)? Entrevistas profundas con personas afectadas enseñan que cultura y proyecto de vida están relacionados fuertemente con lugar e identidad. A través de los resultados un enfoque (approach) de livelihood basado en el concepto de lugar es desarrollado y reúne la teoría de livelihood con la teoría del Buen Vivir.Colombia is the country with the highest number of internally displaced people worldwide. Rural populations often flee violence provoked by the armed conflict. Also so called “development projects” when multinational corporations invest in infrastructure, usually affect local communities. The World Bank provides an Operational Manual (4.12) for “development induced resettlement” to prevent impoverishment. It puts its focus on reimbursing the assets of livelihood of the resettled population. But does the population suffering of displacement share the same approach of livelihood? Can place be replaced? This thesis analyses the case of El Quimbo, a hydroelectric project in the south of Colombia, which displaces a peasant community. In-depth interviews with affected people show that culture and life projects are strongly related to place and identity. Through the findings a place-based livelihood approach is developed, bringing together the livelihood and the Buen Vivir (good life/well-being)approach