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Showing papers by "Technische Universität Darmstadt published in 1995"


Journal ArticleDOI
TL;DR: The paper reviews string fusion into color ropes and hadronic rescattering which serve as models for these interactions for collective interactions in the preequilibrium quark matter andHadronic resonance gas stage of ultrarelativistic nucleus-nucleus collisions.
Abstract: Collective interactions in the preequilibrium quark matter and hadronic resonance gas stage of ultrarelativistic nucleus-nucleus collisions are studied in the framework of the transport theoretical approach RQMD. The paper reviews string fusion into color ropes and hadronic rescattering which serve as models for these interactions. Hadron production in central Pb(160A GeV) on Pb collisions has been calculated. The changes of the final flavor composition are more pronounced than in previous RQMD studies of light ion induced reactions at 200A GeV. The ratio of created quark pairs ss\ifmmode\bar\else\textasciimacron\fi{}/(u\ifmmode \bar{u}\else \={u}\fi{}+dd\ifmmode\bar\else\textasciimacron\fi{}) is enhanced by a factor of 2.4 in comparison to pp results. Color rope formation increases the initially produced antibaryons to 3 times the value in the ``NN mode,'' but only one quarter of the produced antibaryons survives because of subsequent strong absorption. The differences in the final particle composition for Pb on Pb collisions compared to S-induced reactions are attributed to the hadronic resonance gas stage which is baryon-richer and lasts longer.

289 citations


Journal ArticleDOI
TL;DR: In this article, an α-decay chain was observed, which can be unambiguously assigned to 269110, with the mass number 269 of the element 110 on the basis of delayed α-α coincidences.
Abstract: In an experiment carried out to identify element 110, we have observed anα-decay chain, that can be unambiguously assigned to269110. In a scries of preexperiments the excitation functions of the fusion reactions50Ti +208Pb→258104* and58Fe +208Pb→266108* were measured with high precision in order to get the optimum projectile energies for the production of these heavy elements. The cross-section maxima of the 1n evaporation channels were observed at excitation energies of 15.6 MeV and 13.4 MeV, respectively. These data result in an optimum excitation energy of 12.3 MeV of the compound nucleus for the production of269110 in the reaction62Ni +208Pb→269110 + 1n. In irradiations at the corresponding beam energy of 311 MeV we have observed a decay chain of 4 subsequent a decays. This can be assigned to the isotope with the mass number 269 of the element 110 on the basis of delayed α-α coincidences. The accurately measured decay data of the daughter isotopes of the elements 108 to 102, obtained in the previous experiments, were used. The isotope269110 decays with a hair-life of (270 -120 +1300 ) μs by emission of (11.132±0.020) MeV alpha particles. The production cross-section is (3.3 -2.7 +6.2 ) pb.

255 citations


Journal ArticleDOI
TL;DR: In this article, the new element 111 was identified and unambiguously identified in an experiment at SHIP, GSI Darmstadt, and three nuclei of the isotope272111 were observed in irradiations of209Bi targets with64Ni projectiles of 318 MeV and 320 MeV energy.
Abstract: The new element 111 was produced and unambiguously identified in an experiment at SHIP, GSI Darmstadt. Three nuclei of the isotope272111 were observed in irradiations of209Bi targets with64Ni projectiles of 318 MeV and 320 MeV energy. The cross-sections are (1.7 −1.4 +3.3 ) pb and (3.5 −2.3 +4.6 ) pb, respectively. The nuclei decay by a emission into the new and so far the heaviest isotopes of the elements 109 and 107 with mass numbers A=268 and A=264. Theα-decay chains were followed down to the known nuclei260105 and256Lr.

209 citations


Journal ArticleDOI
TL;DR: Matrix-assisted laser desorption/ionization (MALDI) mass spectra and methods to improve their quality are reported for three hydrophobic, membrane-bound proteins: porin from Escherichia coli, bacteriorhodopsin from Halobacterium salinarium and cholesterolesterase from Pseudomonas fluorescens.
Abstract: Matrix-assisted laser desorption/ionization (MALDI) mass spectra and methods to improve their quality are reported for three hydrophobic, membrane-bound proteins: porin from Escherichia coli, bacteriorhodopsin from Halobacterium salinarium and cholesterolesterase from Pseudomonas fluorescens. Several commonly used UV and IR matrices have been tested. In addition, the susceptibility of MALDI mass spectrometry to various neutral and ionic detergents, known usually to degrade the quality of MALDI mass spectra, has been tested systematically. For porin, consisting of three identical non-covalently bound subunits, a new sample preparation is reported, resulting in the desorption of the intact quaternary protein structure. This leads to a better understanding of the way a given analyte is embedded into the host matrix crystals.

190 citations


Journal ArticleDOI
TL;DR: A classification of formulations for the TDTSP is presented and it is shown that, in terms of linear relaxations, the latter formulation is either equivalent or better than other formulations already known from the literature.

133 citations


Journal ArticleDOI
TL;DR: In this article, a geometrical model to describe the cutting process by using ball end milling with a tilt angle is presented, based on which the wear process and optimized cutting conditions for high speed milling of free formed surfaces can be determined.

103 citations


Journal ArticleDOI
TL;DR: In this article, the halo systems Be-11 and Li-11 with a carbon target demonstrate that (n + Li-9) has an (unbound) l = 0 ground state very close to the threshold.
Abstract: Reactions of the halo systems Be-11 and Li-11 (at 460 and 280 MeV/nucleon) with a carbon target demonstrate that (n + Li-9) has an (unbound) l = 0 ground state very close to the threshold. The neutron halo of Li-11 has appreciable (1s(1/2))(2) and (0p(1/2))(2) components.

91 citations


Journal ArticleDOI
TL;DR: In this article, the correlation of these produced particles with respect to the reaction plane was analyzed with the FOPI detector system, and it was shown that baryons exhibit a very pronounced sideward flow pattern which is qualitatively similar to the proton flow.
Abstract: Particles with strange quark content produced in the system 1.93A·GeV58Ni on58Ni have been investigated at GSI Darmstadt with the FOPI detector system. The correlation of these produced particles was analyzed with respect to the reaction plane.Λ baryons exhibit a very pronounced sideward flow pattern which is qualitatively similar to the proton flow. However, the kaon (K +,K s 0 ) flow patterns are significantly different from that of the protons, and their form may be useful to restrict theoretical models on the form of the kaon potential in the nuclear medium.

87 citations


Journal ArticleDOI
TL;DR: A brief review on neozoans in European inland waters shows how processes develop very rapidly in the European waters, particularly in the lowland river systems.
Abstract: The loss of biodiversity — the tendency of the world's fauna to become more and more homogeneous —is widely acknowledged as a problem. Biodiversity is threatened by neozoism and acculturation as much as the extinction of species, but these dangers are less well known. Neozoism and acculturation have an effect on two levels; they lead 1) to an equalisation of the faunal regions and their originally different, specially adapted biocenoses, and 2) to a reduction of genetic diversity below the species level. These processes develop very rapidly in the European waters, particularly in the lowland river systems. The present contribution gives a brief review on neozoans in European inland waters.

84 citations


Journal ArticleDOI
TL;DR: A theoretical model for receptor-controlled cytosolic calcium oscillations and for external influences on the signal transduction pathway is presented and it is argued that these systems form an ideal basis for information-encoding processes in biological systems.
Abstract: Experiments on the effects of extremely-low-frequency (ELF) electric and magnetic fields on cells of the immune system, T-lymphocytes in particular, suggest that the external field interacts with the cell at the level of intracellular signal transduction pathways. These are directly connected with changes in the calcium-signaling processes of the cell. Based on these findings, a theoretical model for receptor-controlled cytosolic calcium oscillations and for external influences on the signal transduction pathway is presented. The authors discuss the possibility that the external field acts on the kinetics of the signal transduction between the activated receptors at the cell membrane and the G-proteins. It is shown that, depending on the specific combination of cell internal biochemical and external physical parameters, entirely different responses of the cell can occur. The authors compare the effects of a coherent (periodic) modulation and of incoherent perturbations (noise). The model and the calculations are based on the theory of self-sustained, nonlinear oscillators. It is argued that these systems form an ideal basis for information-encoding processes in biological systems.

64 citations


Journal ArticleDOI
TL;DR: In this paper, the doubly magic nucleus (Ni50) and the heavy isotopes (Ni,73,74,75Co,80Cu) were produced by nuclear fission in collisions of 750 A·MeV projectiles of 238U on Be target nuclei.
Abstract: We report the first observation of the doubly magic nucleus78Ni50 and the heavy isotopes77Ni,73,74,75Co,80Cu. The isotopes were produced by nuclear fission in collisions of 750 A·MeV projectiles of238U on Be target nuclei. The fully-stripped fission products were separated in-flight by the fragment separator FRS and identified event-by-event by measuring the magnetic rigidity, the trajectory, the energy deposit, and the time of flight. Production cross-sections and fission yields for the new Ni-isotopes are given.

Journal ArticleDOI
TL;DR: Radiation-induced DNA double-strand breaks were measured in CHO-K1 cells by means of an experimental approach involving constant-field gel electrophoresis and densitometric scanning of ethidium bromide stained gels, compared with published results on dsb induction in mammalian cells by radiations of comparable LET.
Abstract: Radiation-induced DNA double-strand breaks (dsbs) were measured in CHO-K1 cells by means of an experimental approach involving constant-field gel electrophoresis and densitometric scanning of ethidium bromide stained gels. For X-irradiation, an induction efficiency of 36 +/- 5 dsbs (Gy x cell)-1 was determined. With this set-up, the induction of dsbs was investigated in CHO-K1 cells after irradiation with accelerated carbon ions with specific energies ranging from 2.7 to 261 MeV/u. This set of particle beams covers the important linear energy transfer (LET) range between 17 and 400 keV/microns, where maximum efficiencies have been reported for other cellular endpoints like inactivation or mutation induction. For LETs up to 100 keV/microns, RBEs of approximately 1 have been determined, while efficiencies per unit dose decline for higher LETs. No RBE maximum > 1 was found. Data are compared with published results on dsb induction in mammalian cells by radiations of comparable LET.

Journal ArticleDOI
TL;DR: It is suggested that cholinesterases in AD function nonclassically as in the embryo, possibly as part of a "neoembryonic" restorative program, and this view may open new strategies for pharmacology and therapy for AD.
Abstract: Summary Evidence about nonclassic functions of acetyl- (AChE) and butyryl-cholinesterase (BChE) during embryonic development of vertebrate brains is compared with evidence of their expression in Alzheimer disease (AD). Before axons extend in the early neural tube, BChE expression shortly precedes the expression of AChE. BChE is associated with neuronal and glial cell proliferation, and it may also regulate AChE. AChE is suggested to guide and stabilize growing axons. Pathologically, cholinesterase expression in AD shows some resemblance to that in the embryo. These findings are inconsistent with the “cholinergic hypothesis.” Rather, it is suggested that cholinesterases in AD function nonclassically as in the embryo, possibly as part of a “neoembryonic” restorative program. These views may open new strategies for pharmacology and therapy for AD.

Book ChapterDOI
01 Jan 1995
TL;DR: An overview of the usage of database systems in the emerging field of multimedia computing systems is given and the notions of hybrid, structural, behavioral, and distributed multimedia systems to classify them are suggested.
Abstract: In this article, we give an overview of the usage of database systems in the emerging field of multimedia computing systems. We motivate that management of multimedia information requires support of temporal relationships, interactive operations, high data volume, and transport of multimedia data. The solutions achieved so far vary to which extend multimedia applications are supported. We suggest to use the notions of hybrid, structural, behavioral, and distributed multimedia systems to classify them. We emphasize the current issues in the area of multimedia database research. Multimedia data modeling, content-based retrieval, continuous storage management, and a distributed architecture are the constituents of multimedia database management systems. The developments achieved so far with the AMOS prototype currently under development at our institutes serve as an illustrating example of current efforts. Specifically, the design of a datatype for audio information, the modeling of meta information and of interactive multimedia presentations, the development of an object manager for continuous objects, and the integration of an information retrieval system in our system are described.

Book ChapterDOI
07 May 1995
TL;DR: This work presents a proof method for intuitionistic logic based on Wallen's matrix characterization that combines the connection calculus and the sequent calculus and reduces the number of extra copies of formulae to be considered.
Abstract: We present a proof method for intuitionistic logic based on Wallen's matrix characterization. Our approach combines the connection calculus and the sequent calculus. The search technique is based on notions of paths and connections and thus avoids redundancies in the search space. During the proof search the computed first-order and intuitionistic substitutions are used to simultaneously construct a sequent proof which is more human oriented than the matrix proof. This allows to use our method within interactive proof environments. Furthermore we can consider local substitutions instead of global ones and treat substitutions occurring in different branches of the sequent proof independently. This reduces the number of extra copies of formulae to be considered.

Journal ArticleDOI
TL;DR: In this article, the phase-space distributions of 3-body events were analyzed by means of an improved version of the kinematic coincidence method and it was shown that 3-and possibly 4-body body events predominantly originate from a two-step mechanism and are compatible with the hypothesis of a binary deep-inelastic interaction followed by the further fissionlike decay of one (or both) of the primary fragments.
Abstract: Events with 2, 3 and 4 heavy fragments (A≥20) detected in the reactions100Mo +100Mo at 18.7, 23.7 A·MeV and120Sn +120Sn at 18.4 A·MeV were analyzed by means of an improved version of the kinematic coincidence method. The phase-space distributions prove that 3- (and possibly 4-) body events predominantly originate from a two-step mechanism and are compatible with the hypothesis of a binary deep-inelastic interaction followed by the further fissionlike decay of one (or both) of the primary fragments. The characteristics of the fission step — mass asymmetry, relative velocity, in-plane and out-of-plane angles — have been reconstructed for the 3-body events and indications are found that nonequilibrium effects at the end of the deep-inelastic phase may influence the fissionlike decay.

Proceedings ArticleDOI
12 Sep 1995
TL;DR: An approach for the self organizing generation of models of complex and unknown processes by means of genetic programming and its application in a biotechnological fed batch production may overcome the specific difficulties that are bound to the use of adaptive or learning-in the sense of neural networks-methods.
Abstract: The article describes an approach for the self organizing generation of models of complex and unknown processes by means of genetic programming and its application in a biotechnological fed batch production. The approach described combines novel results of computer science-genetic programming-with well known and proven techniques of control and system theory-block diagrams and Z transformation. The synthesis of these approaches is a powerful tool for data driven modelling that offers a large number of possibilities to integrate existing knowledge e.g. on submodels or expected elements. The models received by the use of this tool provide a transparent insight into the structure of the process and a basis for long term prediction of the process behaviour and therefore for the determination of optimal setpoint profiles. That means that this approach may overcome the specific difficulties that are bound to the use of adaptive or learning-in the sense of neural networks-methods.

Journal ArticleDOI
TL;DR: A novel method for the generation of fuzzy classification systems based on radial basis function networks with restricted Coulomb energy learning is presented, modified for easy hardware implementation by introducing cubic basis functions.

Proceedings ArticleDOI
22 May 1995
TL;DR: The REACH prototype is one of the first running systems that combines most of the advanced features of aOODBMSs that previously have been shown in partial implementations only and provides a much needed platform for the development of applications.
Abstract: REACH [1] is a full-fledged aOODBMS research platform, that was implemented by extending TI’s OpenOODB [2]. The REACH prototype is one of the first running systems that combines most of the advanced features of aOODBMSs that previously have been shown in partial implementations only. It provides a much needed platform for the development of applications and was instrumented to make performance measurements and visualize the flow of execution. It has a graphical user interface and support tool for rule definition and administration (GRANT). OpenOODB is implemented in an extensible way that resembles the event-driven paradigm of active database systems. A meta-architecture module implements the notions of low-level event, sentry, and policy manager interface. Policy managers are used for handling persistence, transactions, queries, etc. We extended Open OODB with policy managers for event handling and rule execution. REACH implements primitive method events, temporal events, flow control events and the composition operators for sequence, disjunction, conjunction, closure, negation, and history. It uses the C++ type system and detects method events through inline wrapping of the methods in the extended preprocessor of OpenOODB. An ECA rule is mapped to an ECA manager which is accessed during event detection and propagates the event object to the relevant rules implemented as two C functions (for condition and action), which are stored in a shared library [1]. REACH supports a rich set of coupling modes. Rules can be executed either in immediate, deferred or detached mode. Detached mode may be independent or dependent with variants parallel, sequential or exclusive which is used for contingency plans. For details see [1]. Event composition semantics are defined relative to transaction boundaries. Composite events that trigger deferred rules must be composed from events originating in one transaction. Composite events where the constituent events originate in multiple transactions

Book ChapterDOI
07 Jun 1995
TL;DR: An attempt to establish a time-discrete neuron model which is applied to build Radial Basis Function and Multilayer Perceptron networks with distributed dynamics and the well-known delta-rule is extended to the dynamic delta- rule in order to optimize network parameters.
Abstract: An attempt has been made to establish a time-discrete neuron model which is applied to build Radial Basis Function and Multilayer Perceptron networks with distributed dynamics. The well-known delta-rule is extended to the dynamic delta-rule in order to optimize network parameters. Both network types were used to identify empirical, parametrical models of a turbocharger of a Diesel engine which comply with the demanded accuracy properties to a high degree. The performance of both network types is compared according to required number of parameters, approximation accuracy and computational effort.

Journal ArticleDOI
TL;DR: In this paper, positively charged pions and protons from collisions of Ne+NaF and Au+Au at 1 GeV/nucleon incident energy were measured near midrapidity.
Abstract: Positively charged pions and protons from collisions of Ne+NaF and Au+Au at 1 GeV/nucleon incident energy were measured near midrapidity. The center-of-mass pion spectra deviate from a Maxwell-Boltzmann distribution. The slope of the high-energy part of the pion spectra varies significantly with the system mass and little with the size of the reaction zone. While the total pion yield rises linearly with the number of participant nucleons, the highenergy component increases more than linearly.

Journal ArticleDOI
TL;DR: In this article, a number of experimental problems are discussed and the transition rates for new lines in the same wavelength range are compared to the available theoretical data, and the experimental results for these new lines are discussed.
Abstract: N=3, Δn=0 transitions in Na-like ions have been observed and the resonance level lifetimes have been measured by time-resolved spectroscopy of foil-excited ion beams of Xe (Z=54) and Au (Z=79). Other lines in the same wavelength range are identified withn=3, Δn=0 transitions in Ne-, Mg-, and Al-like ions. Wavelengths and transition rates for these new lines are compared to the available theoretical data. A number of experimental problems are discussed.

Journal ArticleDOI
TL;DR: It can be shown that the nearest prototype classifier is functionally equivalent to an alternative fuzzy classifier model, which enables the generation of fuzzy systems in real time.
Abstract: Research in fuzzy neural networks, which started from application oriented fuzzy system tuning, then moving to the automatic generation of fuzzy systems from data, is reaching a more mature stage, especially after the proof of functional equivalence of certain fuzzy models and neural networks. It is essential that the applicability of such developments is explored emphasizing the directions that research should follow. It can be shown that the nearest prototype classifier is functionally equivalent to an alternative fuzzy classifier model. Efficient, hardware friendly training algorithms are developed for dynamic generation of an optimum number of nearest prototypes for neural classifiers which enable the generation of fuzzy systems in real time. These systems are tested with complex applications showing the simulation results.

Journal ArticleDOI
TL;DR: A significantly higher expression ofγGT+ cells in the total MNC populations was observed in B-chronic lymphocytic leukemia (B-CLL) and chronic myelogenous leukemia (CML), whereas other leukemias did not show clear differences, suggesting a possible protective role ofγ GT in MNC and a regulatory function of this enzyme in the development of CML.
Abstract: The expression of the ectoenzymeγ-glutamyl transpeptidase (EC2.3.2.2.,γGT) was investigated by flow cytometry on populations of peripheral blood mononuclear cells (PBMC) from healthy subjects and patients suffering from several types of leukemia before and under chemotherapy. In unstimulated PBMC, 28% of these cells were found to beγGT positive. The highest expression was measured on monocytes (CD14/γGT+ cells: 60%). Within the subsets of T lymphocytes (CD3/γGT+ cells: 18%) we saw no clear differences between CD4+ and CD8+ cells. B lymphocytes, NK cells, and activated cells showed low expressions (up to 10%). Treatment of PBMC with mitogens, α-IFN, IL-2, and GM-CSF did not affect the enzyme expression on normal mononuclear cells (MNC). However, a rapid increase of yGT+ cells was found in the presence of glutathione (GSH) and n-acetyl cysteine (nAC), particularly on monocytes, B cells, and NK cells. Comparing 40 healthy subjects and untreated patients suffering from leukemias, a significantly higher expression ofγGT+ cells in the total MNC populations (B-CLL: 57%, CML: 62%γGT+ cells) was observed in B-chronic lymphocytic leukemia (B-CLL) and chronic myelogenous leukemia (CML), whereas other leukemias did not show clear differences. Most interestingly, theγGT expression was diminished in all populations of CML cells after 5 h of incubation in the presence of 10 units/ml IFN-α. These data suggest a possible protective role ofγGT in MNC and a regulatory function of this enzyme in the development of CML.

Proceedings ArticleDOI
21 May 1995
TL;DR: The peg-in-hole task performed by a system integrating a dextrous hand, a 6-DOF robot and a camera is discussed and a modular concept for solving insertion tasks with a multifingered gripper is presented.
Abstract: This paper discusses the peg-in-hole task performed by a system integrating a dextrous hand, a 6-DOF robot and a camera. It is shown how the starting conditions of the final insertion only performed by the fingers are affected by the previous stages. Based on the experimental findings, some criteria for the overall system design and the required manipulation capabilities of the gripper are derived. With respect to this performance evaluation a modular concept for solving insertion tasks with a multifingered gripper is presented. The object manipulation is realized by primitives which are executed in dependence on various assembly states. The implementation of this approach is described and beside a theoretical characterization, experimental results are given.

Book ChapterDOI
13 Sep 1995
TL;DR: A new concept for real time analysis of images based on the vectorized contours is presented and the formalism to apply the geometric moments to contour patterns is derived and an analysis system for structured textures is presented.
Abstract: In this article a new concept for real time analysis of images based on the vectorized contours is presented. Given the polygone approximation of contours the geometric moments can be formulated for line contours. The resulting line moments (LM's) can be calculated for an arbitrary collection of contour fragments. Neither the existence of an area nor a closed contour is prerequisite to characterize an object by line moments. Due to these properties of the LM's time consuming preprocessing of noisy object contours is not required. Even objects with structured surfaces can be characterized by LM's. The formalism to apply the geometric moments to contour patterns is derived. A direct and a recursive algorithm to efficiently compute the LM's is given. As an application of the LM's an analysis system for structured textures is presented and results are discussed.

Journal ArticleDOI
TL;DR: In this article, the design of a three-dimensional contraction for a projected full-scale aero-acoustic automotive wind tunnel is described, where two interchangeable outlet sections (overall contraction ratio 5.5 and 16.3, respectively) allow either fullscale testing at a test section speed of 45 m/s or 1 4 -model-scale testing up to 75 m /s.

Journal ArticleDOI
TL;DR: In this article, a modification of the conventional inert gas condensation apparatus for making nanostructured powders, wherein an evaporative source is replaced by a chemical source, is described.

Journal ArticleDOI
TL;DR: A dedicated neural network architecture for anomaly detection that can easily be trained by a single presentation of examples and is amenable to massively parallel VLSI implementation is developed.
Abstract: Visual quality control is a demanding task of increasing importance in industrial manufacturing. Both speed and flexibility are of paramount importance for viable and competitive inspection systems. We have developed a dedicated neural network architecture for anomaly detection that can easily be trained by a single presentation of examples and is amenable to massively parallel VLSI implementation. We focus here on our ASIC and prototype system design effort for this network. >

Journal ArticleDOI
TL;DR: In this paper, an acoustic silicon sensor for airborne sound, which is based on boron-implanted monocrystalline piezoresistors located on an electrochemically etched silicon diaphragm, is presented.
Abstract: In this paper experimental results and theoretical considerations of an acoustic silicon sensor for airborne sound, which is based on boron-implanted monocrystalline piezoresistors located on an electrochemically etched silicon diaphragm, are presented. The bandwidth of the sensor is nearly 20 kHz (full audio bandwidth), a maximum sensitivity of 80 μV Pa −1 (bias voltage, 8 V) was achieved and a lowest equivalent noise level of about 61 dB(A) was measured. The membrane thickness is about 1.3 μm; the membrane area amounts to 1 mm 2 . Furthermore, a good reproducibility and linearity could be obtained. The weak sensitivity can mainly be explained by a residual inherent tensile stress in the silicon-silicon dioxide-silicon nitride layer system of the diaphragm and by the large geometric dimensions of the resistors.