114 research outputs found
Schéma de niveaux de 223Ra II. Spectre d'électrons de conversion interne émis dans la désintégration 227Th → 223Ra
Cet article expose l'ensemble de nos études sur les quelques 300 raies de conversion du spectre d'électrons émis dans la désintégration 227 Th → 223Ra : étude par spectrométrie à focalisation semi-circulaire et à double focalisation, ce qui a permis de fixer toutes les intensités en valeur absolue par désintégration α et de fournir un grand nombre de multipolarités
The {\L}ojasiewicz exponent of a set of weighted homogeneous ideals
We give an expression for the {\L}ojasiewicz exponent of a set of ideals
which are pieces of a weighted homogeneous filtration. We also study the
application of this formula to the computation of the {\L}ojasiewicz exponent
of the gradient of a semi-weighted homogeneous function (\C^n,0)\to (\C,0)
with an isolated singularity at the origin.Comment: 15 page
Topological properties of punctual Hilbert schemes of almost-complex fourfolds (I)
In this article, we study topological properties of Voisin's punctual Hilbert
schemes of an almost-complex fourfold . In this setting, we compute their
Betti numbers and construct Nakajima operators. We also define tautological
bundles associated with any complex bundle on , which are shown to be
canonical in -theory
Dosimetric uncertainties related to the elasticity of bladder and rectal walls: Adenocarcinoma of the prostate
Purpose. - Radiotherapy is an important treatment for prostate cancer.During
treatment sessions, bladder and rectal repletion is difficult to quantify and
cannot be measured with a single and initial CT scan acquisition. Some methods,
such as image-guided radiation therapy and dose-guided radiation therapy, aimto
compensate thismissing information through periodic CT acquisitions. The aimis
to adapt patient's position, beam configuration or prescribed dose for a
dosimetric compliance. Methods. -We evaluated organmotion (and repletion) for
54 patients after having computed the original ballistic on a new CT scan
acquisition. A new delineation was done on the prostate, bladder and rectum to
determine the newdisplacements and define organ dosesmistakes (equivalent
uniformdose, average dose and dose-volume histograms). Results. - The new CT
acquisitions confirmed that bladder and rectal volumes were not constant during
sessions. Some cases showed that previously validated treatment plan became
unsuitable. A proposed solution is to correct dosimetries when bladder volume
modifications are significant. The result is an improvement for the stability
of bladder doses, D50 error is reduced by 25.3%, mean dose error by 5.1% and
equivalent uniform dose error by 2.6%. For the rectum this method decreases
errors by only 1%. This process can reduce the risk of mismatch between the
initial scan and following treatment sessions. Conclusion. - For the
proposedmethod, the cone-beamCT is necessary to properly position the isocenter
and to quantify bladder and rectal volume variation and deposited doses. The
dosimetries are performed in the event that bladder (or rectum) volume
modification limits are exceeded. To identify these limits, we have calculated
that a tolerance of 10% for the equivalent uniformdose (compared to the initial
value of the first dosimetry), this represents 11% of obsolete dosimetries for
the bladder, and 4% for the rectum
Radio Astronomy
Contains reports on five research projects.National Science Foundation (Grant AST82-14296)National Aeronautics and Space Administration (Grant NAG W-373)National Aeronautics and Space Administration (Grant NAG5-537)U.S. Navy - Office of Naval Research (Contract N00014-84-C-2082)SM Systems and Research, Inc.Defense Advanced Research Project Agency (Contract MDA903-82-K-0521
Radio Astronomy
Contains summary of research and reports on seven research projects.National Science Foundation (Grant AST82-14296)National Aeronautics and Space Administration (Grant NAGW-373)National Aeronautics and Space Administration (Contract NAS5-28410)U.S. Navy - Office of Naval Research (Contract N00014-84-C-2082)M.I.T. Sloan Fund for Basic ResearchNational Oceanic and Atmospheric Administration (Grant 04-8-M01-1)National Aeronautics and Space Administration (Grant NAG5-10)Defense Advanced Research Project Agency (Contract MDA 903-84-K-0297
Radio Astronomy
Contains summary of research and reports on nine research projects.National Science Foundation (Grant AST81-21416)National Science Foundation (Grant AST82-14296)National Aeronautics and Space Administration (Grant S-10781-C)National Aeronautics and Space Administration (Grant NAGW-373)National Science Foundation (Grant AST79-19553)M.I.T. Sloan Fund for Basic ResearchNational Oceanic and Atmospheric Administration (Grant 04-8-M01-1)National Aeronautics and Space Administration (Grant NAG5-10)National Aeronautics and Space Administration (Contract NAS5-22929)Defense Advanced Research Projects Agency (Contract MDA 903-82-K-0521)Center for Advanced Television Studie
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