254 research outputs found
GRI: The Gamma-Ray Imager mission
With the INTEGRAL observatory, ESA has provided a unique tool to the
astronomical community revealing hundreds of sources, new classes of objects,
extraordinary views of antimatter annihilation in our Galaxy, and fingerprints
of recent nucleosynthesis processes. While INTEGRAL provides the global
overview over the soft gamma-ray sky, there is a growing need to perform
deeper, more focused investigations of gamma-ray sources. In soft X-rays a
comparable step was taken going from the Einstein and the EXOSAT satellites to
the Chandra and XMM/Newton observatories. Technological advances in the past
years in the domain of gamma-ray focusing using Laue diffraction have paved the
way towards a new gamma-ray mission, providing major improvements regarding
sensitivity and angular resolution. Such a future Gamma-Ray Imager will allow
studies of particle acceleration processes and explosion physics in
unprecedented detail, providing essential clues on the innermost nature of the
most violent and most energetic processes in the Universe.Comment: 8 page
Overview of the LISA mission and R&D developments at the APC
International audienceThe study of the gravitational waves opens a new window for the observation of the universe. Completing the observations obtained from electro-magnetic waves, neutrinos and cosmic rays, the gravitational waves will provide informations on the most violent phenomena in the universe, as supernova explosions, collisions of binary systems or mergers of black holes. Their study will thus increase our knowledge in astrophysics, but also in cosmology and fundamental physics. This paper will make a short presentation of the future space interferometer LISA, aiming at detecting gravitational waves, and presents an overview of the R&D developments for LISA at the APC laboratory
The Competition of Wild Oats With Wheat, Barley and Oats for Phosphorus and Potassium
Wild oat plants attained the same heights, weights, and P contents when competing with barley, wheat, oats, or other wild oats al both high and low nutrient concentrations. This same relation was found in the K content of wild oats grown with barley and wheat, but wild oats competing with oats contained less K than those competing with wild oats, and this difference was accentuated with increased nutrient concentrations.
Barley plants grown in competition with wild oats or with other barley plants showed no effects of competitive interaction al either nutrient concentration.
Wheat and oats, like barley, showed no gross growth differences with competing species, but ,both wheat and oats contained more P and K when grown in competition with wild oats than when grown under intraspecific competition. While this interaction was found al both nutrient concentrations, it was more pronounced al the higher one
LISACode : A scientific simulator of LISA
A new LISA simulator (LISACode) is presented. Its ambition is to achieve a
new degree of sophistication allowing to map, as closely as possible, the
impact of the different sub-systems on the measurements. LISACode is not a
detailed simulator at the engineering level but rather a tool whose purpose is
to bridge the gap between the basic principles of LISA and a future,
sophisticated end-to-end simulator. This is achieved by introducing, in a
realistic manner, most of the ingredients that will influence LISA's
sensitivity as well as the application of TDI combinations. Many user-defined
parameters allow the code to study different configurations of LISA thus
helping to finalize the definition of the detector. Another important use of
LISACode is in generating time series for data analysis developments
Imaging the Gamma-Ray Sky with SPI aboard INTEGRAL
The spectrometer SPI on INTEGRAL allows for the first time simultaneous
imaging of diffuse and point-like emission in the hard X-ray and soft gamma-ray
regime. To fully exploit the capabilities of the instrument, we implemented the
MREM image deconvolution algorithm, initially developed for COMPTEL data
analysis, to SPI data analysis. We present the performances of the algorithm by
means of simulations and apply it to data accumulated during the first 2
mission years of INTEGRAL. Skymaps are presented for the 1809 keV gamma-ray
line, attributed to the radioactive decay of 26Al, and for continuum energy
bands, covering the range 20 keV - 3 MeV. The 1809 keV map indicates that
emission is clearly detected by SPI from the inner Galactic radian and from the
Cygnus region. The continuum maps reveal the transition between a point-source
dominated hard X-ray sky to a diffuse emission dominated soft gamma-ray sky.
From the skymaps, we extract a Galactic ridge emission spectrum that matches
well SPI results obtained by model fitting. By comparing our spectrum with the
cumulative flux measured by IBIS from point sources, we find indications for
the existence of an unresolved or diffuse emission component above ~100 keV.Comment: 12 pages, 7 figure
Caractérisation de la cicatrice gliale dans un modèle de compression médullaire : focus sur l'acide hyaluronique
SPI Measurements of the Diffuse Galactic Hard X-ray Continuum
INTEGRAL Spectrometer SPI data from the first year of the Galactic Centre
Deep Exposure has been analysed for the diffuse continuum from the Galactic
ridge. A new catalogue of sources from the INTEGRAL Imager IBIS has been used
to account for their contribution to the celestial signal. Apparently diffuse
emission is detected at a level ~10% of the total source flux. A comparison of
the spectrum of diffuse emission with that from an analysis of IBIS data alone
shows that they are consistent. The question of the contribution of unresolved
sources to this ridge emission is still open.Comment: Proceedings of the 5th INTEGRAL Workshop, Munich 16-20 February 2004.
ESA SP-552. Reference to Terrier et al. (2004) updated to include astro-ph
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THE DEVELOPMENT OF THE AMERICAN SOLO TUBA REPERTOIRE
A very good case can be made that no other instrument has experienced as dramatic an increase in artistic solo repertoire as the tuba in the past sixty years. Prior to 1954, the mainstays of the tuba repertoire were trite caricature pieces such as Solo
Pomposo, Rocked in the Cradle of the Deep, Beelzebub, and Bombastoso. A few tubists, seeing the tremendous repertoire by great composers written for their brass brethren, took it upon themselves to raise the standard of original compositions for tuba. These pioneers and champions of the tuba accomplished a great deal in the mid to late twentieth century. They structured a professional organization to solidify their ranks, planned and performed in the first tuba recitals at Carnegie Hall, organized the First International Tuba Symposium-Workshop, indirectly created more prestigious positions for tuba specialists at major universities, and improved the quantity and quality of the solo tuba repertoire.
This dissertation focuses on the development of the solo repertoire for tuba that happened in the United States because of the tremendous efforts of William Bell,
Harvey Phillips, Roger Bobo, and R. Winston Morris. Because of their tireless work, tuba instrumentalists today enjoy a multitude of great solo works including traditional sonatas, concertos, and chamber music as well as cutting edge repertoire written in many genres and accompanied by a variety of mediums. This dissertation attempts to trace the development of the repertoire presenting the works of American composers in varying genres and musical styles from 1962 to present through three performed recitals
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