Refine
Year of publication
Document Type
- Article (15825)
- Part of Periodical (2818)
- Working Paper (2353)
- Preprint (2085)
- Doctoral Thesis (2065)
- Book (1736)
- Part of a Book (1071)
- Conference Proceeding (753)
- Report (471)
- Review (165)
Language
- English (29537) (remove)
Keywords
- taxonomy (744)
- new species (444)
- morphology (174)
- Deutschland (142)
- Syntax (125)
- Englisch (120)
- distribution (117)
- biodiversity (101)
- Deutsch (98)
- inflammation (97)
Institute
- Medizin (5347)
- Physik (3819)
- Wirtschaftswissenschaften (1921)
- Frankfurt Institute for Advanced Studies (FIAS) (1762)
- Biowissenschaften (1550)
- Center for Financial Studies (CFS) (1494)
- Informatik (1401)
- Biochemie und Chemie (1090)
- Sustainable Architecture for Finance in Europe (SAFE) (1071)
- House of Finance (HoF) (710)
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.
Configuration, simulation and visualization of simple biochemical reaction-diffusion systems in 3D
(2004)
Background In biological systems, molecules of different species diffuse within the reaction compartments and interact with each other, ultimately giving rise to such complex structures like living cells. In order to investigate the formation of subcellular structures and patterns (e.g. signal transduction) or spatial effects in metabolic processes, it would be helpful to use simulations of such reaction-diffusion systems. Pattern formation has been extensively studied in two dimensions. However, the extension to three-dimensional reaction-diffusion systems poses some challenges to the visualization of the processes being simulated. Scope of the Thesis The aim of this thesis is the specification and development of algorithms and methods for the three-dimensional configuration, simulation and visualization of biochemical reaction-diffusion systems consisting of a small number of molecules and reactions. After an initial review of existing literature about 2D/3D reaction-diffusion systems, a 3D simulation algorithm (PDE solver), based on an existing 2D-simulation algorithm for reaction-diffusion systems written by Prof. Herbert Sauro, has to be developed. In a succeeding step, this algorithm has to be optimized for high performance. A prototypic 3D configuration tool for the initial state of the system has to be developed. This basic tool should enable the user to define and store the location of molecules, membranes and channels within the reaction space of user-defined size. A suitable data structure has to be defined for the representation of the reaction space. The main focus of this thesis is the specification and prototypic implementation of a suitable reaction space visualization component for the display of the simulation results. In particular, the possibility of 3D visualization during course of the simulation has to be investigated. During the development phase, the quality and usability of the visualizations has to be evaluated in user tests. The simulation, configuration and visualization prototypes should be compliant with the Systems Biology Workbench to ensure compatibility with software from other authors. The thesis is carried out in close cooperation with Prof. Herbert Sauro at the Keck Graduate Institute, Claremont, CA, USA. Due to this international cooperation the thesis will be written in English.
We investigate the sensitivity of several observables to the density dependence of the symmetry potential within the microscopic transport model UrQMD (ultrarelativistic quantum molecular dynamics model). The same systems are used to probe the symmetry potential at both low and high densities. The influence of the symmetry potentials on the yields of pi-, pi+, the pi-/pi+ ratio, the n/p ratio of free nucleons and the t/3He ratio are studied for neutron-rich heavy ion collisions (208Pb+208Pb, 132Sn+124Sn, 96Zr+96Zr) at E_b=0.4A GeV. We find that these multiple probes provides comprehensive information on the density dependence of the symmetry potential.
DCD – a novel plant specific domain in proteins involved in development and programmed cell death
(2005)
Background: Recognition of microbial pathogens by plants triggers the hypersensitive reaction, a common form of programmed cell death in plants. These dying cells generate signals that activate the plant immune system and alarm the neighboring cells as well as the whole plant to activate defense responses to limit the spread of the pathogen. The molecular mechanisms behind the hypersensitive reaction are largely unknown except for the recognition process of pathogens. We delineate the NRP-gene in soybean, which is specifically induced during this programmed cell death and contains a novel protein domain, which is commonly found in different plant proteins.
Results: The sequence analysis of the protein, encoded by the NRP-gene from soybean, led to the identification of a novel domain, which we named DCD, because it is found in plant proteins involved in d evelopment and c ell d eath. The domain is shared by several proteins in the Arabidopsis and the rice genomes, which otherwise show a different protein architecture. Biological studies indicate a role of these proteins in phytohormone response, embryo development and programmed cell by pathogens or ozone.
Conclusion: It is tempting to speculate, that the DCD domain mediates signaling in plant development and programmed cell death and could thus be used to identify interacting proteins to gain further molecular insights into these processes.
Background: Osteoarthritis (OA) has a high prevalence in primary care. Conservative, guideline orientated approaches aiming at improving pain treatment and increasing physical activity, have been proven to be effective in several contexts outside the primary care setting, as for instance the Arthritis Self management Programs (ASMPs). But it remains unclear if these comprehensive evidence based approaches can improve patients' quality of life if they are provided in a primary care setting. Methods/Design: PraxArt is a cluster randomised controlled trial with GPs as the unit of randomisation. The aim of the study is to evaluate the impact of a comprehensive evidence based medical education of GPs on individual care and patients' quality of life. 75 GPs were randomised either to intervention group I or II or to a control group. Each GP will include 15 patients suffering from osteoarthritis according to the criteria of ACR. In intervention group I GPs will receive medical education and patient education leaflets including a physical exercise program. In intervention group II the same is provided, but in addition a practice nurse will be trained to monitor via monthly telephone calls adherence to GPs prescriptions and advices and ask about increasing pain and possible side effects of medication. In the control group no intervention will be applied at all. Main outcome measurement for patients' QoL is the GERMAN-AIMS2-SF questionnaire. In addition data about patients' satisfaction (using a modified EUROPEP-tool), medication, health care utilization, comorbidity, physical activity and depression (using PHQ-9) will be retrieved. Measurements (pre data collection) will take place in months I-III, starting in June 2005. Post data collection will be performed after 6 months. Discussion: Despite the high prevalence and increasing incidence, comprehensive and evidence based treatment approaches for OA in a primary care setting are neither established nor evaluated in Germany. If the evaluation of the presented approach reveals a clear benefit it is planned to provide this GP-centred interventions on a much larger scale.
We present a detailed study of chemical freeze-out in nucleus-nucleus collisions at beam energies of 11.6, 30, 40, 80 and 158A GeV. By analyzing hadronic multiplicities within the statistical hadronization approach, we have studied the chemical equilibration of the system as a function of center of mass energy and of the parameters of the source. Additionally, we have tested and compared different versions of the statistical model, with special emphasis on possible explanations of the observed strangeness hadronic phase space under-saturation.
Cancer has become one of the most fatal diseases. The Heidelberg Heavy Ion Cancer Therapy (HICAT) has the potential to become an important and efficient treatment method because of its excellent “Bragg peak” characteristics and on-line irradiation control by the PET diagnostics. The dedicated Heidelberg Heavy Ion Cancer Therapy Project includes two ECR ion sources, a RF linear injector, a synchrotron and three treatment rooms. It will deliver 4*10 high 10 protons, or 1*10 high 10 He, or 1*10 high 9 Carbons, or 5*10 high 8 Oxygens per synchrotron cycle with the beam energy 50-430AMeV for the treatments. The RF linear injector consists of a 400AkeV RFQ and of a very compact 7AMeV IH-DTL accelerator operated at 216.816MHz. The development of the IH-DTL within the HICAT project is a great challenge with respect to the present state of the DTL art because of the following reasons: • The highest operating frequency (216.816MHz) of all IH-DTL cavities; • Extremely large cavity length to diameter ratio of about 11; • IH-DTL with three internal triplets; • The highest effective voltage gain per meter (5.5MV/m); • Very short MEBT design for the beam matching. The following achievements have been reached during the development of the IH-DTL injector for HICAT : The KONUS beam dynamics design with LORASR code fulfills the beam requirement of the HICAT synchrotron at the injection point. The simulations for the IH-DTL injector have been performed not only with a homogeneous input beam, but also with the actual particle distribution from the exit of the HICAT RFQ accelerator as delivered by the PARMTEQ code. The output longitudinal normalized emittance for 95% of all particles is 2.00AkeVns, the emittance growth is less than 24%, while the X-X’ and Y-Y’ normalized emittance are 0.77mmmrad and 0.62mmmrad, respectively. The emittance growth in X-X’ is less than 18%, and the emittance growth in Y-Y’ is less than 5%. Based on the transverse envelopes of the transported particles, the redesign of the buncher drift tubes at the RFQ high energy end has been made to get a higher transit time factor for this novel RFQ internal buncher. An optimized effective buncher gap voltage of 45.4KV has been calculated to deliver a minimized longitudinal beam emittance, while the influence of the effective buncher voltage on the transverse emittance can be neglected. Six different tuning concepts were investigated in detail while tuning the 1:2 scaled HICAT IH model cavity. ‘Volume Tuning’ by a variation of the cavity cross sectional area can compensate the unbalanced capacitance distribution in case of an extreme beta-lambda-variation along an IH cavity. ‘Additional Capacitance Plates’ or copper sheets clamped on drift tube stems are a fast way for checking the tuning sensitivity, but they will be replaced by massive copper blocks mounted on the drift tube girders finally. ‘Lens Coupling’ is an important tuning to stabilize the operation mode and to increase or decrease the coupling between neighboring sections. ‘Tube Tuning’ is the fine tuning concept and also the standard tuning method to reach the needed field distributions as well as the gap voltage distributions. ‘Undercut Tuning’ is a very sensitive tuning for the end sections and with respect to the voltage distribution balance along the structure. The different types of ‘plungers’ in the 3rd and 4th sections have different effects on the resonance frequency and on the field distribution. The different triplet stems and the geometry of the cavity end have been also investigated to reach the design field and voltage distributions. Finally, the needed uniform field distribution along the IH-DTL cavity and the corresponding effective voltage distribution were realized, the remaining maximum gap voltage difference was less than 5% for the model cavity. The several important higher order modes were also measured. The RF tuning of the IH-DTL model cavity delivers the final geometry parameters of the IH-DTL power cavity. A rectangular cavity cross section was adopted for the first time for this IH-DTL cavity. This eases the realization of the volume tuning concept in the 1st and 2nd sections. Lens coupling determines the final distance between the triplet and the girder. The triplets are mounted on the lower cavity half shell. The Microwave Studio simulations have been carried out not only for the HICAT model cavity, but also for the final geometry of the IH-DTL power cavity. The field distribution for the operation mode H110 fits to the model cavity measurement as well as the Higher Order Modes. The simulations prove the IH-DTL geometrical design. On the other hand, the precision of one simulation with 2.3 million mesh points for full cross section area and the CPU time more than 15hours on a DELL PC with Intel Pentium 4 of 2.4GHz and 2.096GRAM were exploited to their limit when calculating the real parameters for the two final machining iterations during production. The shunt impedance of the IH-DTL power cavity is estimated by comparison with the existing tanks to about 195.8MOmega/m, which fits to the simulation result of 200.3MOmega/m with reducing the conductivity to the 5.0*10 high 7 Omega-1m-1. The effective shunt impedance is 153 MOmega/m. The needed RF power is 755kW. The expected quality factor of the IH-DTL cavity is about 15600. The IH-DTL power cavity tuning measurements before cavity copper plating have been performed. The results are within the specifications. There is no doubt that the needed accuracy of the voltage distribution will be reached with the foreseen fine tuning concepts in the last steps.
Fluctuations and NA49
(2005)
A systematic analysis of data on strangeness and pion production in nucleon–nucleon and central nucleus–nucleus collisions is presented. It is shown that at all collision energies the pion/baryon and strangeness/pion ratios indicate saturation with the size of the colliding nuclei. The energy dependence of the saturation level suggests that the transition to the Quark Gluon Plasma occurs between 15 A·GeV/c (BNL AGS) and 160 A·GeV/c (CERN SPS) collision energies. The experimental results interpreted in the framework of a statistical approach show that the effective number of degrees of freedom increases in the course of the phase transition and that the plasma created at CERN SPS energies may have a temperature of about 280 MeV (energy density ~ 10 GeV/fm exp-3). The presence of the phase transition can lead to the non–monotonic collision energy dependence of the strangeness/pion ratio. After an initial increase the ratio should drop to the characteristic value for the QGP. Above the transition region the ratio is expected to be collision energy independent. Experimental studies of central Pb+Pb collisions in the energy range 20–160 A·GeV/c are urgently needed in order to localize the threshold energy, and study the properties of the QCD phase transition.
We argue that the measurement of open charm gives a unique opportunity to test the validity of pQCD-based and statistical models of nucleus-nucleus collisions at high energies. We show that various approaches used to estimate D-meson multiplicity in central Pb+Pb collisions at 158 A GeV give predictions which differ by more than a factor of 100. Finally we demonstrate that decisive experimental results concerning the open charm yield in A+A collisions can be obtained using data of the NA49 experiment at the CERN SPS.
Under a conventional policy rule, a central bank adjusts its policy rate linearly according to the gap between inflation and its target, and the gap between output and its potential. Under "the opportunistic approach to disinflation" a central bank controls inflation aggressively when inflation is far from its target, but concentrates more on output stabilization when inflation is close to its target, allowing supply shocks and unforeseen fluctuations in aggregate demand to move inflation within a certain band. We use stochastic simulations of a small-scale rational expectations model to contrast the behavior of output and inflation under opportunistic and linear rules. Klassifikation: E31, E52, E58, E61. July, 2005.
This paper introduces a method for solving numerical dynamic stochastic optimization problems that avoids rootfinding operations. The idea is applicable to many microeconomic and macroeconomic problems, including life cycle, buffer-stock, and stochastic growth problems. Software is provided. Klassifikation: C6, D9, E2 . July 28, 2005.
Groundwater recharge is the major limiting factor for the sustainable use of groundwater. To support water management in a globalized world, it is necessary to estimate, in a spatially resolved way, global-scale groundwater recharge. In this report, improved model estimates of diffuse groundwater recharge at the global-scale, with a spatial resolution of 0.5° by 0.5°, are presented. They are based on calculations of the global hydrological model WGHM (WaterGAP Global Hydrology Model) which, for semi-arid and arid areas of the globe, was tuned against independent point estimates of diffuse groundwater recharge. This has led to a decrease of estimated groundwater recharge under semi-arid and arid conditions as compared to the model results before tuning, and the new estimates are more similar to country level data on groundwater recharge. Using the improved model, the impact of climate change on groundwater recharge was simulated, applying two greenhouse gas emissions scenarios as interpreted by two different climate models.
Prion diseases, also called transmissible spongiform encephalopathies, are a group of fatal neurodegenerative conditions that affect humans and a wide variety of animals. To date there is no therapeutic or prophylactic approach against prion diseases available. The causative infectious agent is the prion, also termed PrPSc, which is a pathological conformer of a cellular protein named prion protein PrPc. Prions are thought to multiply upon conversion of PrPc to PrPSc in a self-propagating manner. Immunotherapeutic strategies directed against PrPc represent a possible approach in preventing or curing prion diseases. Accordingly, it was already shown in animal models, that passive immunization delays the onset of prion diseases. The present thesis aimed at the development of a candidate vaccine towards the active immunization against prion diseases, an immune response, which has to be accompanied by the circumvention of host tolerance to the self-antigen PrPc. The vaccine development was approached using virus-like particles (retroparticles) derived from either the murine leukemia (MLV) or the human immunodeficiency virus (HIV). The display of PrP on the surface of such particles was addressed for both the cellular and the pathogenic form of PrP. The display of PrPc was achieved by either fusion to the transmembrane domain of the platelet derived growth factor receptor (PDGFR) or to the N-terminal part of the viral envelope protein (Env). In both cases, the corresponding PrPD- and PrPE-retroparticles were successfully produced and analyzed via immune fluorescence, Western Blot analysis, immunogold electron microscopy as well as by ELISA methods. Both, PrPD- and PrPE-retroparticles showed effective incorporation of N-terminally truncated forms of PrPc but not for the complete protein. PrPc at this revealed the typical glycosylation pattern, which was specifically removed by a glycosidase enzyme. Upon display of PrPc on retroparticles the protein remained detectable by PrP-specific antibodies under native conditions. Electron microscopy analysis of PrPc-variants revealed no alteration of the characteristic retroviral morphology of the generated particles. MLV-derived PrPD-retroparticles were successfully used in immunization studies. Contrary to approaches using bacterially expressed PrPc, the immunization of mice resulted in a specific antibody response. The display of the pathogenic isoform was aimed by two different strategies. The first one was directed at the conversion of the proteinase K (PK) sensitive from of PrP on the surface of PrPD-retroparticles into the PK resistant form. Albeit specific adaption of the PK digestion assay detecting resistant PrP, no PrP conversion was observed for PrPD-retroparticles. The second approach utilized a replication competent variant of the ecotropic MLV displaying PrPc on the viral Env protein. This MLV variant was stable in cell culture for six passages but did not replicate on scrapie-infected, PrPSc-propagating neuroblastoma cells. Thus, besides PrPc-displaying virus-like particles a replication competent MLV variant was obtained, which stably incorporated PrPc at the N-terminus of the viral Env protein. The incorporation of the cell-surface located PrPc into particles was expected from previously obtained data on protein display in the context of retrovirus-derived particles. Thus, the lack of incorporation observed for the complete PrPc sequence was rather unexpected and was found to be inhibited at both, fusion to PDGFR and the viral Env. In contrast to N-terminally truncated PrPc, the complete PrPc was shown to exhibit increased cell surface internalization rates and half-life times eventually contributing to the observed results. The PrP-vaccination approach described in this work represents the first successful system inducing PrP-specific antibody responses against the prion protein in wt mice. Explanations at this are based on the induction of specific T cell help or effects of the innate immunity, respectively. MLV-and HIV-derived particles bearing the PrP-coding sequence or being replication competent variants generated during this thesis might help to further improve the PrP-specific immune response.
Using CORSIKA for simulating extensive air showers, we study the relation between the shower characteristics and features of hadronic multiparticle production at low energies. We report about investigations of typical energies and phase space regions of secondary particles which are important for muon production in extensive air showers. Possibilities to measure relevant quantities of hadron production in existing and planned accelerator experiments are discussed.
The knowledge of the build up time of space charge compensation (SCC) and the investigation of the compensation process is of main interest for low energy beam transport of pulsed high perveance ion beams under space charge compensated conditions. To investigate experimentally the rise of compensation an LEBT system consisting of a pulsed ion source, two solenoids and a drift tube as diagnostic section has been set up. The beam potential has been measured time resolved by a residual gas ion energy analyser (RGA). A numerical simulation for the calculation of self-consistent equilibrium states of the beam plasma has been developed to determine plasma parameters which are difficult measure directly. The results of the simulation has been compared with the measured data to investigate the behavior of the compensation electrons as a function of time. The acquired data shows that the theoretical rise time of space charge compensation is by a factor of two shorter than the build up time determined experimentally. In view of description the process of SCC an interpretation of the gained results is given.
High perveance negative ion beams with low emittance are essential for several next generation particle accelerators (i. g. spallation sources like ESS [1] and SNS [2]). The extraction and transport of these beams have intrinsic difficulties different from positive ion beams. Limitation of beam current and emittance growth have to be avoided. To fulfill the requirements of those projects a detailed knowledge of the physics of beam formation the interaction of the H- with the residual gas and transport is substantial. A compact cesium free H- volume source delivering a low energy high perveance beam (6.5 keV, 2.3 mA, perveance K= 0.0034) has been built to study the fundamental physics of beam transport and will be integrated into the existing LEBT section in the near future. First measurements of the interaction between the ion beam and the residual gas will be presented together with the experimental set up and preliminary results.
For investigation of space charge compensation process due to residual gas ionization and the experimentally study of the rise of compensation, a Low Energy Beam Transport (LEBT) system consisting of an ion source, two solenoids, a decompensation electrode to generate a pulsed decompensated ion beam and a diagnostic section was set up. The potentials at the beam axis and the beam edge were ascertained from time resolved measurements by a residual gas ion energy analyzer. A numerical simulation of self-consistent equilibrium states of the beam plasma has been developed to determine plasma parameters which are difficult to measure directly. The temporal development of the kinetic and potential energy of the compensation electrons has been analyzed by using the numerically gained results of the simulation. To investigate the compensation process the distribution and the losses of the compensation electrons were studied as a function of time. The acquired data show that the theoretical estimated rise time of space charge compensation neglecting electron losses is shorter than the build up time determined experimentally. To describe the process of space charge compensation an interpretation of the achieved results is given.
Low energy beam transport (LEBT) for a future heavy ion driven inertial fusion (HIDIF [1]) facility is a crucial point using a Bi+ beam of 40 mA at 156 keV. High space charge forces (generalised perveance K=3.6*10-3) restrict the use of electrostatic focussing systems. On the other hand magnetic lenses using space charge compensation suffer from the low particle velocity. Additionally the emittance requirements are very high in order to avoid particle losses in the linac and at ring injection [2]. urthermore source noise and rise time of space charge compensation [3] might enhance particle losses and emittance. Gabor lenses [4] using a continuous space charge cloud for focussing could be a serious alternative to conventional LEBT systems. They combine strong cylinder symmetric focussing with partly space charge compensation and low emittance growth due to lower non linear fields. A high tolerance against source noise and current fluctuations and reduced investment costs are other possible advantages. The proof of principle has already been shown [5, 6]. To broaden the experiences an experimental program was started. Therefrom the first experimental results using a double Gabor lens (DGPL, see fig. 1 ) LEBT system for transporting an high perveance Xe+ beam will be presented and the results of numerical simulations will be shown.
The determination of the beam emittance using conventional destructive methods suffers from two main disadvantages. The interaction between the ion beam and the measurement device produces a high amount of secondary particles. Those particles interact with the beam and can change the transport properties of the accelerator. Particularly in the low energy section of high current accelerators like proposed for IFMIF, heavy ion inertial fusion devices (HIDIF) and spallation sources (ESS, SNS) the power deposited on the emittance measurement device can lead to extensive heat on the detector itself and can destruct or at least dejust the device (slit or grit for example). CCD camera measurements of the incident light emitted from interaction of beam ions with residual gas are commonly used for determination of the beam emittance. Fast data acquisition and high time resolution are additional features of such a method. Therefore a matrix formalism is used to derive the emittance from the measured profile of the beam [1,2] which does not take space charge effects and emittance growth into account. A new method to derive the phase space distribution of the beam from a single CCD camera image using statistical numerical methods will be presented together with measurements. The results will be compared with measurements gained from a conventional Allison type (slit-slit) emittance measurement device.
Investigation of the focus shift due to compensation process for low energy ion beam transport
(2000)
In magnetic Low Energy Beam Transport (LEBT) sections space charge compensation helps to enhance the transportable beam current and to reduce emittance growth due to space charge forces. For pulsed beams the time neccesary to establish space charge compensation is of great interest for beam transport. Particularly with regard to beam injection into the first accelerator section (e.g. RFQ) investigation of effects on shift of the beam focus due to space charge compensation are very important. The achieved results helps to obviate a mismatch into the first RFQ. To investigate the space charge compensation due to residual gas ionization, time resolved measurements using pulsed ion beams were performed at the LEBT system at the IAP and at the CEA-Saclay injektion line. A residual gas ion energy analyser (RGIA) equiped with a channeltron was used to measure the potential destribution as a function of time to estimate the rise time of compensation. For time resolved measurements (delta t min=50ns) of the radial density profile of the ion beam a CCD-camera was applied. The measured data were used in a numerical simulation of selfconsistant eqilibrium states of the beam plasma [1] to determine plasma parameters such as the density, the temperature, the kinetic and potential energy of the compensation electrons as a function of time. Measurements were done using focused proton beams (10keV, 2mA at IAP and 92keV, 62mA at CEA-Saclay) to get a better understanding of the influence of the compensation process. An interpretation of the acquired data and the achieved results will be presented.
Influence of space charge fluctuations on the low energy beam transport of high current ion beams
(2000)
For future high current ion accelerators like SNS, ESS or IFMIF the beam behaviour in low energy beam transport sections is dominated by space charge forces. Therefore space charge fluctuations (e. g. source noise) can drastically influence the beam transport properties of the low energy beam transport section. Losses of beam ions and emittance growth are the most severe problems. For electrostatic transport systems either a LEBT design has to be found which is insensitive to variations of the space charge or the origin of the fluctuations has to be eliminated. For space charge compensated transport as proposed for ESS and IFMIF the situation is different: No major influence on beam transport is expected for fluctuations below a cut-off frequency given by the production rate of the compensation particles. Above this frequency the fluctuations can not be compensated by particle production alone, but redistributions of the compensation particles helps to compensate the influence of the fluctuations. Above a second cut-off frequency given by the density and the temperature of the compensation particles their redistribution is too slow to reduce the influence of the space charge fluctuations. Transport simulations for the IFMIF injector including space charge fluctuations will be presented together with a determination of the cut-off frequencies. The results will be compared with measurements of the rise time of space charge compensation.
New results on the production of Xi and Omega hyperons in Pb+Pb interactions at 40 A GeV and Lambda at 30 A GeV are presented. Transverse mass spectra as well as rapidity spectra of these hyperons are shown and compared to previously measured data at different beam energies. The energy dependence of hyperon production (4Pi yields) is discussed. Additionally, the centrality dependence of Xi- production at 40 A GeV is presented.
First results on the production of Xi- and Anti-xi hyperons in Pb+Pb interactions at 40 A GeV are presented. The Anti-xi/Xi- ratio at midrapidity is studied as a function of collision centrality. The ratio shows no significant centrality dependence within statistical errors; it ranges from 0.07 to 0.15. The Anti-xi/Xi- ratio for central Pb+Pb collisions increases strongly with the collision energy.
High perveance negative ion beams with low emittance are essential for several next generation particle accelerators (i. g. spallation sources like ESS [1] and SNS [2]). The extraction and transport of these beams have intrinsic difficulties different from positive ion beams. Limitation of beam current and emittance growth have to be avoided. To fulfill the requirements of those projects a detailed knowledge of the physics of beam formation the interaction of the H- with the residual gas and transport is substantial. A compact cesium free H- volume source delivering a low energy high perveance beam (6.5 keV, 2.3 mA, perveance K= 0.0034) has been built to study the fundamental physics of beam transport and will be integrated into the existing LEBT section in the near future. First measurements of the interaction between the ion beam and the residual gas will be presented together with the experimental set up and preliminary results.
A LEBT system consisting of an ion source, two solenoids, and a diagnostic section has been set up to investigate the space charge compensation process due to residual gas ionization [1] and to study experimentally the rise of compensation. To gain the radial beam potential distribution time resolved measurements of the residual gas ion energy distribution were carried out using a Hughes Rojanski analyzer [2,3]. To measure the radial density profile of the ion beam a CCD-camera performed time resolved measurements, which allow an estimation the rise time of compensation. Further the dynamic effect of the space charge compensation on the beam transport was shown. A numerical simulation under assumption of selfconsistent states [4] of the beam plasma has been used to determine plasma parameters such as the radial density profile and the temperature of the electrons. The acquired data show that the theoretical estimated rise time of space charge compensation neglecting electron losses is shorter than the build up time determined experimentally. An interpretation of the achieved results is given.
To fulfil the requirements of ESS on beam transmission and emittance growth a detailed knowledge of the physics of beam formation as well as the interaction of the H- with the residual gas is substantial. Space charge compensated beam transport using solenoids for ion optics is in favour for the Low Energy Beam Transport (LEBT) between ion source and the first RFQ. Space charge compensation reduces the electrical self fields and beam radii and therefore emittance growth due to aberrations and redistribution. Transport of H- near the ion source is negatively influenced by the dipole fields required for beam extraction and e--dumping and the high gas pressure. The destruction of the rotational symmetry together with the space charge forces causes emittance growth and particle losses within the extraction system. High residual gas pressure near the extractor together with the high cross section for stripping will influence the transmission as well as space charge compensation. Therefore a detailed knowledge of the interaction of the residual gas with the beam and the influence of the external fields on the distribution of the compensation particles is necessary to reduce particle losses and emittance growth. Preliminary experiments using positive hydrogen ions for reference already show the influence of dipole fields on beam emittance. First measurements with H- confirm these results. Additional information on the interactions of the residual gas with the beam ions have been gained from the measurements using the momentum and energy analyser.
Vortrag gehalten an der Tagung "The XVI International Conference on Ultrarelativistic Nucleus-Nucleus Collisions, organized by SUBATECH Laboratory", in Nantes, France, 18-24 Juli 2002.
Rapidity distributions for Lambda and anti-Lambda hyperons in central Pb-Pb collisions at 40, 80 and 158 AGeV and for K 0 s mesons at 158 AGeV are presented. The lambda multiplicities are studied as a function of collision energy together with AGS and RHIC measurements and compared to model predictions. A different energy dependence of the Lambda/pi and anti-Lambda/pi is observed. The anti-Lambda/Lambda ratio shows a steep increase with collision energy. Evidence for a anti-Lambda/anti-p ratio greater than 1 is found at 40 AGeV.
The experiment NA49 at the CERN SPS is a large acceptance detector for charmed hadrons. The identification of neutral strange hadrons Lambda and AntiLambda is based on the measurement of their charged decay particles and the reconstruciton of the decay vertex. The charged particles were measured with the 4 time projection chambers (TPC), two of them are situated inside 2 large dipole magnets, the two others are downstream of the magnet. Lambda and AntiLambda baryons have been measured in central Pb+Pb collisions at 40, 80 and 160 GeV/nucleon over a wide range in rapidity (1 - 5) and transverse momentum (0 - 3 GeV/c). Particle yields and spectra will be shown for the different energies. The results will be put into the existing systematics of Lambda-production as a function of beam energy.
In this paper we present recent results from the NA49 experiment for Lambda and Lambda hyperons produced in central Pb+Pb collisions at 40, 80 and 158 A GeV. Transverse mass spectra and rapidity distributions for Lambda are shown for all three energies. The shape of the rapidity distribution becomes flatter with increasing beam energy. The multiplicities at mid-rapidity as well as the total yields are studied as a function of collision energy including AGS measurements. The ratio Lambda/pi at mid-rapidity and in 4 pi has a maximum around 40 A GeV. In addition, Lambda rapidity distributions have been measured at 40 and 80 A GeV, which allows to study the Lambda Lambda ratio.
Excitation functions for quasi-elastic scattering have been measured at backward angles for the systems 32,34S+197Au and 32,34S+208Pb for energies spanning the Coulomb barrier. Representative distributions, sensitive to the low energy part of the fusion barrier distribution, have been extracted from the data. For the fusion reactions of 32,34S with 197Au couplings related to the nuclear structure of 197Au appear to be dominant in shaping the low energy part of the barrier distibution. For the system 32S+208Pb the barrier distribution is broader and extends further to lower energies, than in the case of 34S+208Pb. This is consistent with the interpretation that the neutron pick-up channels are energetically more favoured in the 32S induced reaction and therefore couple more strongly to the relative motion. It may also be due to the increased collectivity of 32S, when compared with 34S.
S.a. Deutsche Fassung: Ökonomie der Gabe - Positivität der Gerechtigkeit: Gegenseitige Heimsuchungen von System und différance. In: Albrecht Koschorke und Cornelia Vismann (Hg.) System - Macht - Kultur: Probleme der Systemtheorie. Akademie, Berlin 1999, 199-212. Auch auf unserem Server vorhanden. * Italienische Fassung: Economia del dono, positività della giustizia: la reciproca paranoia di Jacques Derrida e Niklas Luhmann. Sociologia e politiche sociali 6, 2003, 113-130. Portugiesische Fassung: Economia da dádiva ? posividade da rustica; ?assombracao?? mutua entre sistema e différance. In: Gunther Teubner, Direito, Sistema, Policontexturalidade, Editora Unimep, Piracicaba Sao Paolo, Brasil 2005, 55-78.
Globalized justice - fragmented justice. Human rights violations by "private" transnational actors
(2005)
Plenarvortrag Weltkongress der Rechtsphilosophie und Sozialphilosophie, 24.-29. Mai, Granada 2005. S.a. die deutsche Fassung: "Die anonyme Matrix: Menschenrechtsverletzungen durch "private" transnationale Akteure". Spanische Fassung: Sociedad global, justicia fragmentada: sobre la violatión de los derechos humanos por actores transnacionales 'privados'. In: Manuel Escamilla and Modesto Saavedra (eds.), Law and Justice in a global society, International Association for philosophy of law and social philosophy, Granada 2005, S. 529-546.
"Eurocomprehension" is the term used to describe European intercomprehension in Europe’s three major language families, the Romance, the Slavic and the Germanic. The aim of eurocomprehension is to achieve multilingualism conforming to EU language policy goals through the entry-point of receptive competence in a modular structure. Linguistic intercomprehension research forms the transfer bases for the cognitive use of relations between the language groups which didactics of multilingualism implement. ...
Deutsche Fassung: Expertise als soziale Institution: Die Internalisierung Dritter in den Vertrag. In: Gert Brüggemeier (Hg.) Liber Amicorum Eike Schmidt. Müller, Heidelberg, 2005, 303-334.
Deutsche Fassung: Vertragswelten: Das Recht in der Fragmentierung von private governance regimes. Rechtshistorisches Journal 17, 1998, 234-265. Italienische Fassung: Mondi contrattuali. Discourse rights nel diritto privato. In: Gunther Teubner, Diritto policontesturale: Prospettive giuridiche della pluralizzazione dei mondi sociali. La città del sole, Neapel 1999, 113-142. Portugiesische Fassung: Mundos contratuais: o direito na fragmentacao de regimes de private governance. In: Gunther Teubner, Direito, Sistema, Policontexturalidade, Editora Unimep, Piracicaba Sao Paolo, Brasil 2005, 269-298.
s.a. Deutsche Fassung: Rechtshistorisches Journal 15, 1996, 255-290 und in: Eric Schwarz (Hg.) La théorie des systèmes: une approche inter- et transdisciplinaire. Bösch, Sion 1996, 101-119. Italienische Fassung: La Bukowina globale: il pluralismo giuridico nella società mondiale. Sociologic a politiche sociali 2, 1999, 49-80. Portugiesische Fassung: Bukowina global sobre a emergência de um pluralismo jurídico transnacional. Impulso: Direito e Globalização 14, 2003. Georgische Fassung: Globaluri bukovina: samarTlebrivi pluralizmi msoflio sazogadoebaSi. Journal of the Institute of State and Law of the Georgian Academy of Sciences 2005 (im Erscheinen)
s.a. Deutsche Fassung: Archiv für Rechts- und Sozialphilosophie. Beiheft 65, 1996, 199-220. Italienische Fassung: Altera pars audiatur: Il diritto nella collisione dei discorsi. In: Gunther Teubner, Diritto policontesturale: Prospettive giuridiche della pluralizzazione dei mondi sociali. La città del sole, Neapel 1999, 27-70. Französische Fassung: Altera pars audiatur: le droit dans la collision des discours. Droit et Société 35, 1997, 99-123. Portugiesische Fassung: Altera pars audiatur: o direito na colisao de disursos. In: J.A. Lindgren Alves, Gunther Teubner, Joaquim Leonel de Rezende Alvim, Dorothe Susanne Rüdiger, Direito e Cidadania na Pos-Modernidade. Editora Unimep, Piracicaba, Brasilia 2002; 93-129.
Reflexives Recht. Entwicklungsmodelle des Rechts in vergleichender Perspektive (EUI Working Paper 1982/13). Archiv für Rechts- und Sozialphilosophie 68, 1982, 13-59, und in: Werner Maihofer (Hg.), Noi si Mura, Schriftenreihe des Europäischen Hochschulinstituts, Florenz 1986, 290-340. Englische Fassung: Substantive and Reflexive Elements in Modern Law. (EUI Working Paper 1982/14). Law and Society Review 17, 1983, 239-285 und in: Kahei Rokumoto (Hg.) Sociological Theories of Law. Dartmouth, Aldershot 1994, 415-462. Neuabdruck in: Carroll Seron, The Law and Society Canon, Ashgate, Aldershot 2005 (im Erscheinen). Französische Fassung: Eléments 'substantifs' et 'réflexifs' dans le droit moderne. L'Interdit. Revue de Psychanalyse Institutionelle, 1984, 129-132, und Droit et réflexivité: une perspective comparative sur des modèles d'évolution juridique in: Gunther Teubner, Droit et réflexivité. Librairie générale de droit et de jurisprudence, Paris 1994, 3-50. Dänische Fassung: Refleksiv Ret: Udviklingsmodeller i sammenlignende perspektiv. In: Asmund Born, Nils Bredsdorff, Leif Hansen and Finn Hansson (Hg.) Refleksiv Ret. Publication Series of the Institut for Organisation og Arbeidssociologi. Nytfrasamfundsvidenskaberne, Kopenhagen 1988, 21-79.
We introduce a new method for representing and solving a general class of non-preemptive resource-constrained project scheduling problems. The new approach is to represent scheduling problems as de- scriptions (activity terms) in a language called RSV, which allows nested expressions using pll, seq, and xor. The activity-terms of RSV are similar to concepts in a description logic. The language RSV generalizes previous approaches to scheduling with variants insofar as it permits xor's not only of atomic activities but also of arbitrary activity terms. A specific semantics that assigns their set of active schedules to activity terms shows correctness of a calculus normalizing activity terms RSV similar to propositional DNF-computation. Based on RSV, this paper describes a diagram-based algorithm for the RSV-problem which uses a scan-line principle. The scan-line principle is used for determining and resolving the occurring resource conflicts and leads to a nonredundant generation of all active schedules and thus to a computation of the optimal schedule.
In the last years, much effort went into the design of robust anaphor resolution algorithms. Many algorithms are based on antecedent filtering and preference strategies that are manually designed. Along a different line of research, corpus-based approaches have been investigated that employ machine-learning techniques for deriving strategies automatically. Since the knowledge-engineering effort for designing and optimizing the strategies is reduced, the latter approaches are considered particularly attractive. Since, however, the hand-coding of robust antecedent filtering strategies such as syntactic disjoint reference and agreement in person, number, and gender constitutes a once-for-all effort, the question arises whether at all they should be derived automatically. In this paper, it is investigated what might be gained by combining the best of two worlds: designing the universally valid antecedent filtering strategies manually, in a once-for-all fashion, and deriving the (potentially genre-specific) antecedent selection strategies automatically by applying machine-learning techniques. An anaphor resolution system ROSANA-ML, which follows this paradigm, is designed and implemented. Through a series of formal evaluations, it is shown that, while exhibiting additional advantages, ROSANAML reaches a performance level that compares with the performance of its manually designed ancestor ROSANA.
In the last decade, much effort went into the design of robust third-person pronominal anaphor resolution algorithms. Typical approaches are reported to achieve an accuracy of 60-85%. Recent research addresses the question of how to deal with the remaining difficult-toresolve anaphors. Lappin (2004) proposes a sequenced model of anaphor resolution according to which a cascade of processing modules employing knowledge and inferencing techniques of increasing complexity should be applied. The individual modules should only deal with and, hence, recognize the subset of anaphors for which they are competent. It will be shown that the problem of focusing on the competence cases is equivalent to the problem of giving precision precedence over recall. Three systems for high precision robust knowledge-poor anaphor resolution will be designed and compared: a ruleset-based approach, a salience threshold approach, and a machine-learning-based approach. According to corpus-based evaluation, there is no unique best approach. Which approach scores highest depends upon type of pronominal anaphor as well as upon text genre.
Assessing enhanced knowledge discovery systems (eKDSs) constitutes an intricate issue that is understood merely to a certain extent by now. Based upon an analysis of why it is difficult to formally evaluate eKDSs, it is argued for a change of perspective: eKDSs should be understood as intelligent tools for qualitative analysis that support, rather than substitute, the user in the exploration of the data; a qualitative gap will be identified as the main reason why the evaluation of enhanced knowledge discovery systems is difficult. In order to deal with this problem, the construction of a best practice model for eKDSs is advocated. Based on a brief recapitulation of similar work on spoken language dialogue systems, first steps towards achieving this goal are performed, and directions of future research are outlined.
In the last years, much effort went into the design of robust anaphor resolution algorithms. Many algorithms are based on antecedent filtering and preference strategies that are manually designed. Along a different line of research, corpus-based approaches have been investigated that employ machine-learning techniques for deriving strategies automatically. Since the knowledge-engineering effort for designing and optimizing the strategies is reduced, the latter approaches are considered particularly attractive. Since, however, the hand-coding of robust antecedent filtering strategies such as syntactic disjoint reference and agreement in person, number, and gender constitutes a once-for-all effort, the question arises whether at all they should be derived automatically. In this paper, it is investigated what might be gained by combining the best of two worlds: designing the universally valid antecedent filtering strategies manually, in a once-for-all fashion, and deriving the (potentially genre-specific) antecedent selection strategies automatically by applying machine-learning techniques. An anaphor resolution system ROSANA-ML, which follows this paradigm, is designed and implemented. Through a series of formal evaluations, it is shown that, while exhibiting additional advantages, ROSANAML reaches a performance level that compares with the performance of its manually designed ancestor ROSANA.