Hectospec, the MMT's 300 Optical Fiber-Fed Spectrograph

The Hectospec is a 300 optical fiber fed spectrograph commissioned at the MMT in the spring of 2004. A pair of high-speed six-axis robots move the 300 fiber buttons between observing configurations within ~300 s and to an accuracy ~25 microns. The optical fibers run for 26 m between the MMT's focal surface and the bench spectrograph operating at R~1000-2000. Another high dispersion bench spectrograph offering R~5,000, Hectochelle, is also available. The system throughput, including all losses in the telescope optics, fibers, and spectrograph peaks at ~10% at the grating blaze in 1" FWHM seeing. Correcting for aperture losses at the 1.5" diameter fiber entrance aperture, the system throughput peaks at $\sim$17%. Hectospec has proven to be a workhorse instrument at the MMT. Hectospec and Hectochelle together were scheduled for 1/3 of the available nights since its commissioning. Hectospec has returned \~60,000 reduced spectra for 16 scientific programs during its first year of operation.Comment: 68 pages, 28 figures, to appear in December 2005 PAS

Determination of the pion-nucleon coupling constant and scattering lengths

We critically evaluate the isovector GMO sum rule for forward pion-nucleon scattering using the recent precision measurements of negatively charged pion-proton and pion-deuteron scattering lengths from pionic atoms. We deduce the charged-pion-nucleon coupling constant, with careful attention to systematic and statistical uncertainties. This determination gives, directly from data a pseudoscalar coupling constant of 14.11+-0.05(statistical)+-0.19(systematic) or a pseudovector one of 0.0783(11). This value is intermediate between that of indirect methods and the direct determination from backward neutron-proton differential scattering cross sections. We also use the pionic atom data to deduce the coherent symmetric and antisymmetric sums of the negatively charged pion-proton and pion-neutron scattering lengths with high precision. The symmetric sum gives 0.0012+-0.0002(statistical)+-0.0008 (systematic) and the antisymmetric one 0.0895+-0.0003(statistical)+-0.0013(systematic), both in units of inverse charged pion-mass. For the need of the present analysis, we improve the theoretical description of the pion-deuteron scattering length.Comment: 27 pages, 5 figures, submitted to Phys. Rev. C, few modifications and clarifications, no change in substance of the pape

Glueballs, Hybrids, Multiquarks. Experimental facts versus QCD inspired concepts

The spectroscopy of light and heavy mesons is reviewed with emphasis on glueballs, hybrids, and tetraquarks.Comment: 266 pages, 117 figures, 39 tables. to be published in Physics Report

Small fluorescence-activating and absorption-shifting tag for tunable protein imaging in vivo

International audienceThis paper presents Yellow Fluorescence-Activating and absorption-Shifting Tag (Y-FAST), a small monomeric protein tag, half as large as the green fluorescent protein, enabling fluorescent labeling of proteins in a reversible and specific manner through the reversible binding and activation of a cell-permeant and nontoxic fluorogenic ligand (a so-called fluorogen). A unique fluorogen activation mechanism based on two spectroscopic changes, increase of fluorescence quantum yield and absorption red shift, provides high labeling selectivity. Y-FAST was engineered from the 14-kDa photoactive yellow protein by directed evolution using yeast display and fluorescence-activated cell sorting. Y-FAST is as bright as common fluorescent proteins, exhibits good photostability, and allows the efficient labeling of proteins in various organelles and hosts. Upon fluorogen binding, fluorescence appears instantaneously, allowing monitoring of rapid processes in near real time. Y-FAST distinguishes itself from other tagging systems because the fluorogen binding is highly dynamic and fully reversible, which enables rapid labeling and unlabeling of proteins by addition and withdrawal of the fluorogen, opening new exciting prospects for the development of multiplexing imaging protocols based on sequential labeling

A Blue-Absorbing Photolabile Protecting Group for <i>in Vivo</i> Chromatically Orthogonal Photoactivation

The small and synthetically easily accessible 7-diethylamino-4-thiocoumarinylmethyl photolabile protecting group has been validated for uncaging with blue light. It exhibits a significant action cross-section for uncaging in the 470–500 nm wavelength range and a low light absorption between 350 and 400 nm. These attractive features have been implemented in living zebrafish embryos to perform chromatic orthogonal photoactivation of two biologically active species controlling biological development with UV and blue-cyan light sources, respectively

TWAC : EIC Pathfinder Open European project on Novel dielectric acceleration

International audienceParticle accelerators are devices of primary importance in a large range of applications such as fundamental particle physics, nuclear physics, light sources, imaging, neutron sources, and transmutation of nuclear waste. They are also used every day for cargo inspection, medical diagnostics, and radiotherapy worldwide. Electron is the easiest particle to produce and manipulate, resulting in unequaled energy over cost ratio.However, there is an urgent and growing need to reduce the footprint of accelerators in order to lower their cost and environmental impact, from the future high-energy colliders to the portable relativistic electron source for industrial and societal applications. The radical new vision we propose will revolutionize the use of accelerators in terms of footprint, beam time delivery, and electron beam properties (stability, reproducibility, monochromaticity, femtosecond-scale bunch duration), which is today only a dream for a wide range of users. We propose developing a new structure sustaining the accelerating wave pushing up the particle energy, which will enable democratizing the access to femtosecond-scale electron bunch for ultrafast phenomena studies.This light and compact accelerator, for which we propose breaking through the current technological barriers, will open the way toward compact accelerators with an energy gain gradient of more than 100 MeV/m and enlarge time access in the medical environment (preclinical and clinical phase studies)

Les ONG et l'éducation

Les ONG, qu'elles agissent à l'échelle d'un pays ou à l'international, sont aujourd'hui, dans de nombreux domaines, les partenaires des États, des bailleurs de fonds et des populations. Elles sont très présentes dans le champ de l'éducation, sous des formes extrêmement variées. Leurs apports, comme les limites de leur intervention, font l'objet de ce numéro 58 de la Revue internationale d'éducation de Sèvres consacré à un thème encore peu abordé par la recherche. Illustrant des cas, des géographies et des contextes variés, principalement au Sud, le dossier reflète les questionnements et les points de vue différents de bailleurs de fonds, d'ONG, ainsi que de chercheurs français et étrangers. Quelle est aujourd'hui la place, quels sont les modes de fonctionnement et les logiques d'intervention des ONG, au regard d'activités qui relèvent généralement de la responsabilité des États ? Quel rôle jouent-elles dans l'évolution des politiques éducatives, principalement dans les pays en développement, ainsi qu'auprès des populations concernées ? Quels nouveaux acteurs, quelles pratiques innovantes voit-on émerger dans ce vaste secteur de l'aide au développement ? Ce numéro ouvre de nombreuses pistes de réflexion, afin de stimuler un débat encore naissant. Un dossier coordonné par Sandra Barlet (Gret) , avec Jean-Pierre Jarousse (Université de Rennes 2) NGOs, whether they operate in a single country or at international level, act as partners to States, sponsors, and peoples in a wide range of fields. Their presence is particularly felt in education, where it takes a great variety of forms. Their contributions, along with the limits set on their intervention, are the subject of No.58 of the Revue Internationale d'Education de Sèvres, which is devoted to a topic that research has so far only barely touched upon. With examples drawn from a variety of cases, geographies and contexts, mainly in the South, this special issue reflects the different questions and viewpoints of sponsors and NGOs themselves, as well as of French and foreign researchers. What place do NGOs have today, how do they operate, and what is their intervention with regard to activities for which States are usually seen as being responsible? What role do they play in the evolution of educational policies, in particular in developing countries, and in the lives of the peoples concerned? What new actors and innovative practices emerge in this vast sector of aid to development? Coordination: Sandra Barlet (GRET), with Jean-Pierre Jarousse. Las ONG, que actúan a escala de un país o en el plano internacional, son en la actualidad, en numerosos ámbitos, los socios de los Estados, de los proveedores de fondos y de las poblaciones. Están muy presentes en el campo de la educación, bajo formas extremadamente variadas. Sus aportes, como los límites de su intervención, son objeto de este número 58 de la Revue internationale d'éducation de Sèvres consagrada a un tema aún poco abordado por la investigación. Ilustrando casos, geografías y contextos variados, principalmente en el Sur, el expediente refleja los cuestionamientos y los puntos de vista diferentes de proveedores de fondos, de ONG, así como de investigadores franceses y extranjeros. ¿Cuál es el lugar hoy en día, cuáles son los modos de funcionamiento y las lógicas de intervención de las ONG, con respecto a actividades que generalmente competen a la responsabilidad de los Estados? ¿Qué función desempeñan en la evolución de las políticas educativas, principalmente en los países en desarrollo, así como ante las poblaciones concernidas? ¿Qué nuevos protagonistas, qué prácticas innovadoras se ven surgir en este extenso sector de la ayuda al desarrollo? Un dossier coordinado por Sandra Barlet (GRET) con Jean-Pierre Jarouss