Studies of Hadronic Event Structure in e+e- Annihilation from 30 GeV to 209 GeV with the L3 Detector

In this Report, QCD results obtained from a study of hadronic event structure in high energy e^+e^- interactions with the L3 detector are presented. The operation of the LEP collider at many different collision energies from 91 GeV to 209 GeV offers a unique opportunity to test QCD by measuring the energy dependence of different observables. The main results concern the measurement of the strong coupling constant, \alpha_s, from hadronic event shapes and the study of effects of soft gluon coherence through charged particle multiplicity and momentum distributions.Comment: To appear in Physics Report

A new generation of satellite based solar rradiance calculation schemes

International audienceA successful integration of solar energy into the existing energy structure highly depends on a detailed knowledge of the solar resource. HELIOSAT-3 will supply high-quality solar radiation data gained from the exploitation of existing Earth observation technologies and will take advantage of the enhanced capabilities of the new Meteosat Second Generation (MSG) satellites. The expected quality represents a substantial improvement with respect to the available methods and will better match the needs of companies and other customers of the resulting products. These goals will be achieved by an improvement of the current semi-empirical Heliosat calculation schemes (see section 2) as well as by the development and establishment of a new type of calculation scheme. This new type will be based on radiative transfer models (RTM) using the information of atmospheric parameters retrieved from the MSG satellite (clouds, ozone, water vapor) and the GOME/ATSR-2 satellites (aerosols). Within this paper, the new type of the solar irradiance calculation scheme, including the functional treatment of the diurnal variation of the solar irradiance, is described

A two-component regulatory system playing a critical role in plant pathogens and endosymbionts is present in Brucella abortus and controls cell invasion and virulence

Two mutants showing increased sensitivity to polycations and surfactants were obtained by transposon mutagenesis of virulent Brucella abortus 2308 Nal(r). These mutants showed no obvious in vitro growth defects and produced smooth-type lipopolysaccharides. However, they hardly multiplied or persisted in mouse spleens, displayed reduced invasiveness in macrophages and HeLa cells, lost the ability to inhibit lysosome fusion and were unable to replicate intracellularly. Subsequent DNA analyses identified a two-component regulatory system [Brucella virulence related (Bvr)] with a regulatory (BvrR) and sensory (BvrS) protein. Cloning on bvrR in the BvrR-deficient mutant restored the resistance to polycations and, in part, the invasiveness to polycations and, in part, the invasiveness and the ability to multiply intracellularly. BvrR and BvrS were highly similar (87-89% and 70-80% respectively) to the regulatory and sensory proteins of the chromosomally encoded Rhizobium meliloti Chvl-ExoS and Agrobacterium tumefaciens Chvl-ChvG systems previously shown to be critical for endosymbiosis and pathogenicity in plants. Divergence among the three sensory proteins was located mostly within a periplasmic domain probably involved in stimulus sensing. As B. abortus, R. meliloti and A. tumefaciens are phylogenetically related, these observations suggest that these systems have a common ancestor that has evolved to sense stimuli in plant and animal microbial environments.Dos mutantes que muestran una mayor sensibilidad a los policationes y a los tensioactivos se obtuvieron por mutagénesis de transposones de la Brucella abortus 2308 Nal(r) virulenta. Estos mutantes no mostraron defectos evidentes de crecimiento in vitro y produjeron lipopolisacáridos de tipo suave. Sin embargo, apenas se multiplicaron o persistieron en el bazo de los ratones, mostraron una menor capacidad de invasión en macrófagos y células HeLa, perdieron la capacidad de inhibir la fusión de lisosomas y fueron incapaces de replicarse intracelularmente. Los análisis posteriores del ADN identificaron un sistema regulador de dos componentes [Brucella virulence related (Bvr)] con una proteína reguladora (BvrR) y otra sensorial (BvrS). La clonación en bvrR en el mutante deficiente en BvrR restauró la resistencia a los policationes y, en parte, la capacidad de invasión a los policationes y, en parte, la capacidad de invasión y de multiplicación intracelular. BvrR y BvrS eran muy similares (87-89% y 70-80% respectivamente) a las proteínas reguladoras y sensoriales de los sistemas Rhizobium meliloti Chvl-ExoS y Agrobacterium tumefaciens Chvl-ChvG codificados cromosómicamente, que habían demostrado ser críticos para la endosimbiosis y la patogenicidad en las plantas. La divergencia entre las tres proteínas sensoriales se localizó sobre todo en un dominio periplásmico probablemente implicado en la detección de estímulos. Dado que B. abortus, R. meliloti y A. tumefaciens están filogenéticamente relacionados, estas observaciones sugieren que estos sistemas tienen un ancestro común que ha evolucionado para percibir estímulos en entornos microbianos vegetales y animales.Universidad Nacional, Costa RicaEscuela de Medicina Veterinari