Showing papers by "Fraunhofer Society published in 1988"

Thermally excited silicon microactuators

Abstract: A cantilever-type micromachined silicon actuator based on the bimetal effect used extensively for the fabrication of temperature-controlled electrical switches is described. The silicon actuator consists of a Si-metal sandwich layer and an integrated poly-Si heating resistor as a driving element. Due to the low heat capacity of the transducer element, a high temperature increase per input power unit can be achieved. For a (Si-Au)-cantilever-type actuator, 500- mu m long and several micrometers thick, a specific deflection of approximately 0.1 mu m/K at the free end has been measured. The design considerations, fabrication process, and experimental results of the actuator are discussed. >

Development of the pattern of cell renewal in the crypt-villus unit of chimaeric mouse small intestine

Abstract: We have previously shown that the epithelium of each adult intestinal crypt in chimaeric mice is derived from a single progenitor cell. Whether the crypts are monoclonal from the outset-that is, are formed by the proliferation of a single cell-or whether their formation is initiated by several cells was not known. Here we report that many crypts contain cells of both chimaeric genotypes in the neonatal period indicating a polyclonal origin at this stage of morphogenesis. The cellular organization of the early neonatal crypt is therefore different from that of the adult crypt, which includes a zone of ‘anchored’ stem cells above the crypt base. Within 2 weeks, however, the crypt progenitor cell and its descendants displace all other cells from the crypt and the crypt attains monoclonality. The distribution of enterocytes on chimaeric villi in the neonate shows a mottled pattern of mosaicism which is progressively replaced by coherent sheets of cells from the crypts, and within two weeks the orderly adult clonal pattern is established.

Toward a symbolic representation of intensity changes in images

Abstract: The symbolic representation of gray-value variations is studied, with emphasis on the gradient of the image function. The goal is to relate the results of this analysis to the structure of the picture, which is determined by the physics of the image generation process. Candidates for contour points are the maximal magnitudes of the gray-value gradient for different scales in the direction of the gradient. Based on the output of such a bank of gradient filters, a procedure is proposed to select automatically a suitable scale, and with that, the size of the right convolution kernel. The application of poorly adapted filters, which make the exact localization of gray-value corners or T-, X-, and Y-junctions more difficult, is thus avoided. Possible gaps at such junctions are discussed for images of real scenes, and possibilities for the closure of some of these gaps are demonstrated when the extrema of the magnitudes of the gray-value gradients are used. >

The genotoxicity of lucidin, a natural component of Rubia tinctorum L., and lucidinethylether, a component of ethanolic Rubia extracts.

Abstract: The genotoxic activity of lucidin (1,3-dihydroxy-2-hydroxymethyl-9,10-anthraquinone), a natural component of Rubia tinctorum L., was tested in a battery of short-term tests. The compound was mutagenic in five Salmonella typhimurium strains without metabolic activation, but the mutagenicity was increased after addition of rat liver S9 mix. In V79 cells, lucidin was mutagenic at the hypoxanthine-guanine phosphoribosyl transferase gene locus and active at inducing DNA single-strand breaks and DNA-protein cross-links as assayed by the alkaline elution method. Lucidin also induced DNA repair synthesis in primary rat hepatocytes and transformed C3H/M2-mouse fibroblasts in culture. We also investigated lucidinethylether, which is formed from lucidin by extraction of madder roots with boiling ethanol. This compound was also mutagenic in Salmonella, but only after addition of rat liver S9 mix. Lucidinethylether was weakly mutagenic to V79 cells which were cocultivated with rat hepatocytes. The compound did not induce DNA repair synthesis in hepatocytes from untreated rats, but positive results were obtained when hepatocytes from rats pretreated with phenobarbital were used. We conclude that lucidin and its derivatives are genotoxic.

Urinary and faecal excretion of chrysene and chrysene metabolites by rats after oral, intraperitoneal, intratracheal or intrapulmonary application

Abstract: The urinary and faecal excretion of chrysene and its phenolic metabolites after oral, intraperitoneal, intratracheal, and intrapulmonary administration to rats have been studied by means of gas chromatography/mass spectrometry The metabolite profile was found to depend on the mode of excretion and on the route of administration In all cases the oxidation of chrysene in the 1,2- or 3,4-position predominates, whereas oxidation in the 5,6-position (K-region) seems be a minor pathway

VISTA: visual interpretation system for technical applications -architecture and use

Abstract: The present state of the construction of a vision system for the fast interpretation of complicated industrial scenes is reported. The system is being built at the Fraunhofer Institute for Information and Data Process in Karlsruhe, West Germany. The scenes for which the system is intended are also presented. They form the basis for specifying the requirements for the system called VISTA. Its principal architecture as a bus-oriented multiprocessor system is discussed. Some special hardware modules of VISTA are described in more detail, and its basic software concept is introduced. As an application, detection and classification of defects that appear in automatic visual inspection of hard wood are reviewed. Using special modules for the iconic and the symbolic stage, VISTA is capable of real-time processing and evaluation of endless images, image sequences, images of various formats, and multisensorial data. >

On the application of a new method for fast and robust position control of industrial robots

Abstract: A concept called predictive functional control (PFC) is presented for industrial robot (IR) control. It provides excellent control performance, a high accuracy even for fast trajectories, an outstanding tracking quality for sharp contour deviations, and a very good robustness with respect to parameter variations. It is shown that PFC can be implemented on conventional IR control systems. The performance is demonstrated by several experimental results. >

Simulation of dry etch processes by COMPOSITE

Abstract: Anetch simulator that allows modeling of dry etch processes by means of rates, fitting functions, and models is presented. Isotropic etching by chemically active neutrals, sputtering by energetic ions, and anisotropic etching by ion-induced chemistry can be considered. The simulation of secondary effects such as redeposition and trenching as well as polymerization effects is possible. Some applications are presented to demonstrate the possibilities of the new program. This etch simulator is part of the process modeling program COMPOSITE, which is able to simulate the complete fabrication process of integrated circuits. >

Chapter 6 – Direct Manipulation

Abstract: Publisher Summary This chapter discusses the concept of direct manipulation (DM). DM is characterized by several principles. The chapter describes a number of examples that show typical characteristics of DM. A screen editor as opposed to line-oriented editors displays the document in its actual form. Some editors present the text exactly as it would look on the printout, with immediate feedback on modifications. Spreadsheets might employ the metaphor of an accountant's worksheet to convey an easily comprehensible visual representation of the data with their complex arithmetic and logical relationships, which is always current with respect to the actual state of the calculations. Spatial management systems and graphical browsers might use DM principles for orientation and navigation in large complex data structures. Video games, CAD/CAM systems, or query-by-example database retrieval are other examples of applications where DM can be used. A number of favorable usability attributes can be achieved by using DM interaction techniques.

Characterization of active layers in GaAs by microwave absorption

Abstract: Free carrier electric microwave absorption is applied to the analysis of ion implanted and epitaxial active layers in GaAs. An improved version of a previously reported waveguide system is described. It allows a quick and nondestructive determination of the sheet resistance, carrier concentration and carrier mobility of active layers. The usefulness of the method for routine electric material characterization supporting a microelectronic device fabrication is demonstrated. Finally, some explorative microwave measurements of heterostructures and photo-induced effects are reported.

Compensator design by frequency-weighted approximation

Abstract: The author believes, that the approach which is outlined for scalar problems has two major benefits: it provides a basis to introduce more effective computer assistance in the design process as compared to the usual presentation of frequency response graphs and performance indices; and it creates a bridge between the classical approach and more sophisticated methods like LQG- or mod H/sup infinity /-design. The author first reviews the classical design specifications and explains their underlying assumptions. This leads to a new understanding of the design process and to an algorithmic formulation. The approach is illustrated by a non-trivial design example, and unsolved problems are outlined together with perspectives for extensions of the method. >

Towards autonomous convoy driving: recognizing the starting vehicle in front

Abstract: The problem of automatically detecting a leading vehicle in the process of starting off and deriving a model for further tracking is addressed. Very little knowledge about the appearance of the vehicle is utilized. Motion information is the main cue for selecting image structures belonging to the leading vehicle. An edge model is derived from two independent, complementary motion-estimation processes that cross-validate each other. The suitability of the aggregated model for recognition and the precision of the motion estimation process are demonstrated by means of an image sequence consisting of 130 TV images. >

Extracellular killing of Leishmania promastigotes and amastigotes by macrophage precursors derived from bone marrow cultures.

Abstract: Flagellates of the genus Leishmania are obligate intracellular parasites of vertebrates including man. The microorganisms reside and multiply inside the phagolysosomes of cells of the mononuclear phagocyte lineage. We here report on the spontaneous leishmanicidal activity exerted extracellularly by immature cells of the mononuclear phagocyte lineage. Highly purified, bone marrow-derived macrophage precursor cells displayed a strong spontaneous leishmanicidal activity already at very low effector/target rations (3:1, 6:1). This leishmanicidal activity was effective against both promastigotes and amastigotes as targets. The cytotoxic effect was evident within 4 h and maximal after 12 h of effector-target organism cocultivation, as determined by a radiolabel-release assay. An intimate cell-cell contact seemed necessary for the parasites to be killed.

Low Noise - Low Power CMOS Readout Systems for Silicon Strip Detectors

Abstract: Two readout systems for silicon strip detectors (128-and 64-channels) have has been developed in CMOS technology. The readout systems have been designed for a readout pitch of 50?m and 100?m, respectively. They provide signal amplification, noise filtering, parallel storage, and serial readout and contain a digital contol for analog switching. Switched-capacitor filters are used in all channels for noise reduction by multi-correlated double sampling. Power consumption is controlled by an external reference voltage thus allowing for optimization of speed and noise behavior versus power consumption for individual use in experiments. Power-down mode for further reduction of power dissipation is available without switching off the supply voltages. A high charge amplification (15mV/fC) and a good noise performance (335 ENC + 30 ENC/pF) have been obtained at a very low power consumption of 2mW per channel.

Liver‐associated macrophage precursor cells proliferate under impairment of regular hemopoiesis

Abstract: We reported previously that immature macrophage precursor cells can be isolated from spleen and liver of cyclophosphamide or pyran copolymer-pretreated mice. We now extended our investigations to livers of normal, untreated specific pathogen-free mice. Using the response to the macrophage growth factor colony-stimulating factor-1 (CSF-1) and the presence of the mouse macrophage-specific F4/80 antigen as criteria of definition, in the liver of normal mice we could demonstrate macrophage precursor (M phi P) cells by means of proliferation assays and flow cytometric analysis. The amount of M phi P present in the normal liver was significantly increased after administration of pyran copolymer. Also an enhanced proliferative response to CSF-1 as well as augmented natural killer activity and cytostasis of Candida albicans was noted in liver nonparenychymal cells (LNPC) after treatment of bone marrow (BM)-irradiated, splenectomized mice with pyran copolymer. Since the irradiated BM was actually proven to be silent by assessment of BM number and proliferative capacity and by scoring white blood cells, our findings suggest a response of endogenous liver M phi P under the applied conditions. Further evidence for the presence of endogenous liver hemopoietic cells was obtained from transplantation experiments in which LNPC brought about the survival of lethally irradiated mice. The data point towards a significance of the liver in disposing hemopoietic cells to the organism under impairment of regular hemopoiesis.

Recrystallized silicon thin film structure for solar cells

Abstract: The technological sequence for the realization of crystalline silicon thin-film solar cells is described. The sequence consists of the deposition of an oxide layer (thermal or by PECVD) on different substrates (monocrystalline or polycrystalline silicon), etching of windows into this layer by means of a photolithographic process, deposition of microcrystalline Si layers (by LPCVD) on top of the oxide layer, and recrystallization of these Si layers by a special surface melting technique. During solidification, substantial grain growth is observed leading to grain diameters in the millimeter range. This is due to a special seeding technique. >

A Plasma Focus as Radiation Source for a Laboratory X-Ray Microscope

Abstract: To open the X-ray microscopy to a wider range of applications there is need for a user oriented tool for routine biological investigations, which is located in the laboratories of biologists. The requirements are defined by the specimen to be examined: They are entire cells in culture, nuclei or other organells, wet and thick (0.1 – 10 μm). There should be only short delay between preparation and experiment. The specimen should stay under atmospheric conditions and room temperature during examination. In order to eliminate blurring due to the motion of the cell and due to radiation damage the exposure time should be as short as possible.

Technological standards for research-intensive product groups and international competitiveness

Abstract: Summary The paper presents a quantitative model for the assessment of technological standards, which is applied to a sample of data compiled in 1986 comparing technical specifications of R&D-intensive product groups of US, Japanese, and West German origin. The merits and the limitations of this model as well as of comparable concepts and approaches published within the last few years are discussed in a systematic manner. It is found that few of the previously published concepts aim at a quantitative comparison of solely technological specifications on the level of national economies. The ‘technometric’ model introduced in this paper therefore attempts to fill an analytical gap. Technological disparities and national technological standards are presented in the fields of lasers, industrial robots, sensors, photovoltaic modules, immobilized biocatalysts, and genetically engineered drugs. Instead of selecting R&D-intensive products from controversial ‘High Technology’ lists, specified trade subclasses are related to the corresponding technological product specifications for selected and more precisely defined products. Time series up to 1985 for the relative export-import indicator RCA (‘revealed comparative advantage’) for West Germany versus the United States, Japan, and several other countries (depending on the technology under consideration) are discussed and the quantitative findings are characterized by the different competitive positions held by these countries. Finally, trade positions are related to technological standards. Despite the limitations of the technical and economic indicator concepts one arrives at the conclusion that the factor ‘technology’, and thus applied R&D output, seems to be a very important one when interpreting international competitiveness. Other factors, such as trade barriers, management ability, and exchange rates probably cannot compensate for technological disparities. But the correspondence of disaggregated trade classes and technologies remains a serious problem. For the six technological fields indicated above these shortcomings and classification problems are discussed, and hence the requirements for future data bases and future scientific work in the field of technical and economic indicators are sketched.

Formant tracking with quasilinearization

Abstract: An algorithm for the calculation of formant tracks from a speech signal is presented. It is based on the method of quasilinearization, a nonlinear parameter estimation procedure. What distinguishes this method from the most other methods is the fact that the formants are directly calculated from the speech signal, using a nonlinear model for the speech production that is based on formants and LPC parameters (FLPC model). Since quasilinearization is a nonrecursive parameter estimation method, this procedure is also much faster than nonlinear estimation algorithms for formant tracking which are based on extended Kalman filters. >

A data model supporting system engineering

Abstract: The PRODAT is a nonstandard application-oriented database system which allows for the representation of design objects, supports the design process during the whole life-cycle, and permits cooperation between several designers or design tools. The data model of PRODAT is presented, with attention given to the notion of simple and structured objects and the version and configuration management facilities. The practical usability of the model is demonstrated in a case study. >

The potential of reconstructability analysis for production research

Abstract: Reconstructability analysis is a package of methodological tools for dealing with the relationship between wholes and parts in the context of computer-aided systems modelling. The applicability of reconstructability analysis in industrial engineering and production reseach, which is the primary purpose of this paper, is illustrated by simple examples based upon data obtained from psychophysiological and ergonomic experiments under real working conditions.

Experiment Alsdan (1985): Some Preliminary Results of Height Resolved Measurements of Trace Gases, Aerosol Composition, Cloud- and Precipitation Water

Abstract: In- and below-cloud scavenging experiments were performed at Deuselbach (49.8°N, 7.2°E), a rural site in West Germany, in April/May and October/November 1985. Cloud water samples were collected on two platforms of a TV-tower on top of a hill (861 m and 821 m a.s.l.), while rain was sequentially sampled at 754 m, 480 m, and 430 m a.s.l. Cloud- and rainwater samples were analyzed for conductivity, major anions, cations, and H2O2. We also monitored the mixing ratios of SO2, NO, NO2, O3 in air and standard meteorological parameters at 821 m and 480 m a.s.l. At the same locations, HNO3, HC1, NH3, and aerosol were measured by discontinuous sampling. The experiments were generally limited to meteorologically simple precipitation events, like frontal rains. A preliminary analysis of the data shows that the trace substance concentrations in cloudwater at the cloud base always exceed those of rainwater by a factor of 1.5 – 4. Also within the cloud a concentration gradient is observed with higher concentrations at the cloud base. Aerosol particles (r > 0.5 µm) seem to be effectively scavenged by rain droplets, while scavenging of trace gases was barely detectable except in the case of HNO3.