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Search Results: 1 - 10 of 5816 matches for " Markus Stock "
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A detailed dosimetric comparison between manual and inverse plans in HDR intracavitary/interstitial cervical cancer brachytherapy
Petra Trnková,Dimos Baltas,Andreas Karabis,Markus Stock
Journal of Contemporary Brachytherapy , 2010,
Abstract: Purpose: The purpose of this study was to compare two inverse planning algorithms for cervical cancer brachytherapy and a conventional manual treatment planning according to the MUW (Medical University of Vienna) protocol.Material and methods: For 20 patients, manually optimized, and, inversely optimized treatment plans with Hybrid Inverse treatment Planning and Optimization (HIPO) and with Inverse Planning Simulated Annealing (IPSA) were created. Dosimetric parameters, absolute volumes of normal tissue receiving reference doses, absolute loading times of tandem, ring and interstitial needles, Paddick and COIN conformity indices were evaluated.Results: HIPO was able to achieve a similar dose distribution to manual planning with the restriction of high dose regions. It reduced the loading time of needles and the overall treatment time. The values of both conformity indices were the lowest. IPSA was able to achieve acceptable dosimetric results. However, it overloaded the needles.This resulted in high dose regions located in the normal tissue. The Paddick index for the volume of two times prescribed dose was outstandingly low.Conclusions: HIPO can produce clinically acceptable treatment plans with the elimination of high dose regions in normal tissue. Compared to IPSA, it is an inverse optimization method which takes into account current clinical experience gained from manual treatment planning.
Imaginaries Imagined
Stock, Femke
Ars Disputandi : the Online Journal for Philosophy of Religion , 2006,
L’habiter comme pratique des lieux géographiques.
Mathis Stock
EspacesTemps.net , 2004,
Abstract: Comment appréhender les dimensions spatiales des sociétés humaines ? Afin d’y apporter des éléments de réponse à l’un des questionnements fondamentaux de la géographie, on propose ici une perspective particulière centrée sur les manières dont les individus pratiquent les lieux, bref l’habiter. En effet, deux éléments de contexte concourent à proposer un questionnement centré sur l’habiter : d’abord, un contexte scientifique qui fait que les questions des valeurs ou ...
Les sociétés à individus mobiles : vers un nouveau mode d’habiter ?
Mathis Stock
EspacesTemps.net , 2005,
Abstract: On constate aujourd’hui une mobilité géographique accrue des individus pour l’essentiel de leurs pratiques. La mobilité géographique change de multiples fa ons le rapport aux lieux des individus. En effet, on assiste à une recomposition des lieux familiers et des lieux étrangers pour les individus. Ce ne sont pas nécessairement les lieux proches qui sont les plus familiers. Cette recomposition se laisse appréhender de fa on particulièrement claire dans le cas des pratiques ...
L’hypothèse de l’habiter poly-topique : pratiquer les lieux géographiques dans les sociétés à individus mobiles.
Mathis Stock
EspacesTemps.net , 2006,
Abstract: Une nouvelle fa on d’habiter le Monde s’est développée : elle est essentiellement informée par la mobilité spatiale de biens matériels, d’informations ou de personnes. Ce développement d’une mobilité spatiale accrue concerne le fondement de l’être-ensemble, de l’économie, des pratiques individuelles, du politique ainsi que la solution de différents problèmes posés aux sociétés humaines. Quelques chiffres, livrés en vrac et dans un arbitraire total, donnent une ...
Relativistic Nuclear Collisions
Reinhard Stock
Physics , 2009,
Abstract: A comprehensive introduction is given to the field of relativistic nuclear collisions, and the phase diagram of strongly interacting matter. The content of this complex of reviews is shown.
The Parton-Hadron Phase Transition in Central Nuclear Collisions at the CERN SPS
Reinhard Stock
Physics , 1999, DOI: 10.1016/S0146-6410(99)00084-8
Abstract: A selection of recent data referring to Pb+Pb collisions at the SPS CERN energy of 158 GeV per nucleon is presented which might describe the state of highly excited strongly interacting matter both above and below the deconfinement to hadronization (phase) transition predicted by lattice QCD. A tentative picture emerges in which a partonic state is indeed formed in central Pb+Pb collisions which hadronizes at about T = 185 MeV, and expands its volume more than tenfold, cooling to about 120 MeV before hadronic collisions cease. We suggest further that all SPS collisions, from central S+S onward, reach that partonic phase, the maximum energy density increasing with more massive collision systems.
Relativistic Nucleus-Nucleus Collisions: from the BEVALAC to RHIC
Reinhard Stock
Physics , 2004, DOI: 10.1088/0954-3899/30/8/001
Abstract: I briefly describe the initial goals of relativistic nuclear collisions research, focusing on the LBL Bevatron/Bevalac facility in the 1970's. An early concept of high hadronic density fireball formation, and subsequent isentropic decay (preserving information as to the high density stage) led to an outline of physics observables that could determine the nuclear matter equation of state at several times nuclear ground state matter density. With the advent of QCD the goal of locating, and characterizing the hadron-parton deconfinement phase transformation suggested the need for higher $\sqrt{s}$, the research thus moving to the BNL AGS and CERN SPS, finally to RHIC at BNL. A set of physics observables is discussed where present data span the entire $\sqrt{s}$ domain, from Bevalac and SIS at GSI, to top RHIC energy. Referring, selectively, to data concerning bulk hadron production, the overall $\sqrt{s}$ evolution of directed and radial flow observables, and of pion pair Bose-Einstein correlation are discussed. The hadronization process is studied in the grand canonical statistical model. The resulting hadronization points in the plane T vs. $\mu_B$ converge onto the parton-hadron phase boundary predicted by finite $\mu_B$ lattice QCD, from top SPS to RHIC energy. At lower SPS and top AGS energy a steep strangeness maximum occurs at which the Wroblewski parameter $\lambda_s \approx $ 0.6; a possible connection to the QCD critical point is discussed. Finally the unique new RHIC physics is addressed: high $p_T$ hadron suppression and jet "tomography".
Relativistic Nucleus-Nucleus Collisions and the QCD Matter Phase Diagram
Reinhard Stock
Physics , 2008, DOI: 10.1007/978-3-540-74203-6_7
Abstract: This review will be concerned with our knowledge of extended matter under the governance of strong interaction, in short: QCD matter. Strictly speaking, the hadrons are representing the first layer of extended QCD architecture. In fact we encounter the characteristic phenomena of confinement as distances grow to the scale of 1 fm (i.e. hadron size): loss of the chiral symmetry property of the elementary QCD Lagrangian via non-perturbative generation of "massive" quark and gluon condensates, that replace the bare QCD vacuum. However, given such first experiences of transition from short range perturbative QCD phenomena (jet physics etc.), toward extended, non perturbative QCD hadron structure, we shall proceed here to systems with dimensions far exceeding the force range: matter in the interior of heavy nuclei, or in neutron stars, and primordial matter in the cosmological era from electro-weak decoupling (10^-12 s) to hadron formation (0.5 10^-5 s). This primordial matter, prior to hadronization, should be deconfined in its QCD sector, forming a plasma (i.e. color conducting) state of quarks and gluons: the Quark Gluon Plasma (QGP).
The parton to hadron phase transition observed in Pb+Pb collisions at 158 GeV per nucleon
Reinhard Stock
Physics , 1999, DOI: 10.1016/S0370-2693(99)00482-7
Abstract: Hadronic yields and yield ratios observed in Pb+Pb collisions at the SPS energy of 158 GeV per nucleon are known to resemble a thermal equilibrium population at T=180 +/- 10 MeV, also observed in elementary e+ + e- to hadron data at LEP. We argue that this is the universal consequence of the QCD parton to hadron phase transition populating the maximum entropy state. This state is shown to survive the hadronic rescattering and expansion phase, freezing in right after hadronization due to the very rapid longitudinal and transverse expansion that is inferred from Bose-Einstein pion correlation analysis of central Pb+Pb collisions.
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