Showing papers by "Fraunhofer Society published in 1989"

Macrophage Activation by the Polysaccharide Arabinogalactan Isolated From Plant Cell Cultures of Echinacea purpurea

Abstract: In this study, acidic arabinogalactan, a highly purified polysaccharide from plant cell cultures of Echinacea purpurea, with a molecular weight of 75,000, was effective in activating macrophages to cytotoxicity against tumor cells and micro-organisms (Leishmania enriettii). Furthermore, this polysaccharide induced macrophages to produce tumor necrosis factor (TNF-alpha), interleukin-1 (IL-1), and interferon-beta 2. Arabinogalactan did not activate B cells and did not induce T cells to produce interleukin-2, interferon-beta 2, or interferon-gamma, but it did induce a slight increase in T-cell proliferation. When injected ip, this agent stimulated macrophages, a finding that may have therapeutic implications in the defense against tumors and infectious diseases.

Speaker adaptation for large vocabulary speech recognition systems using speaker Markov models

Abstract: An alternative approach to speaker adaptation for a large-vocabulary hidden-Markov-model-based speech recognition system is described. The goal of this investigation was to train the IBM speech recognition system with only five minutes of speech data from a new speaker instead of the usual 20 minutes without the recognition rate dropping by more than 1-2%. The approach is based on the use of a stochastic model representing the different properties of the new speaker and an old speaker for which the full training set of 20 minutes is available. It is called a speaker Markov model. It is shown how the parameters of such a model can be derived and how it can be used for transforming the training set of the old speaker in order to use it in addition to the short training set of the new speaker. The adaptation algorithm was tested with 12 speakers. The average recognition rate dropped from 96.4% to 95.2% for a 5000-word vocabulary task. The decoding time increased by a factor of 1.35; this factor is often 3-5 if other adaptation algorithms are used. >

Heterotrophic nitrification by Alcaligenes faecalis: NO2-, NO3-, N2O, and NO production in exponentially growing cultures.

Abstract: Heterotrophic nitrification by Alcaligenes faecalis DSM 30030 was not restricted to media containing organic forms of nitrogen. In both peptone-meat extract and defined media with ammonium and citrate as the sole nitrogen and carbon sources, respectively, NO2-, NO3-, NO, and N2O were produced under aerobic growth conditions. Heterotrophic nitrification was not attributable to old or dying cell populations. Production of NO2-, NO3-, NO, and N2O was detectable shortly after cultures started growth and proceeded exponentially during the logarithmic growth phase. NO2- and NO3- production rates were higher for cultures inoculated in media with pH values below 7 than for those in media at alkaline pH. Neither assimilatory nor dissimilatory nitrate or nitrite reductase activities were detectable in aerobic cultures.

Evidence for the existence of two forms of membrane tumor necrosis factor: an integral protein and a molecule attached to its receptor.

Abstract: Plasma membranes were isolated from thioglycolate-induced peritoneal mouse macrophages and tested directly in a 51Cr-release assay against WEHI 164 tumor cells. These membranes showed anti-TNF antibody inhibitable killing of the TNF-sensitive tumor cell line, indicating that membrane-associated TNF is present on mouse macrophages. In order to elucidate whether membrane TNF is an integral protein or a molecule attached to a receptor, cells and plasma membranes were treated with low pH buffer. A partial reduction in TNF activity was observed which could be restored by incubation with exogenous TNF. In a Western blot analysis the integral membrane TNF could be identified as the 26-kDa molecule on activated mouse macrophages. These results indicate that both forms of membrane-associated TNF exist on macrophages and are responsible for cell-mediated cytotoxicity against TNF-alpha-sensitive targets.

A very-high-slew-rate CMOS operational amplifier

Abstract: The amplifier uses a circuit to inject an extra bias current into a conventional source-coupled CMOS differential input stage in the presence of large differential input signals. This measure substantially increases the slew rate of an operational amplifier for a given quiescent current. The performance of the amplifier is compared to a conventional operational amplifier when used in a sample-and-hold circuit. The maximum operating clock frequency of the sample-and-hold increases from 290 kHz to 1 MHz with a hold capacitor of 1 nF. The amplifier has been fabricated in a 5- mu m CMOS process and dissipates a static power of 7.5 mW. >

On a constraint equation for the estimation of displacement rates in image sequences

Abstract: The commonly used constraint equation Delta g/sup T/u+g/sub t/=0 for the estimation of optical flow can only be justified by assumptions that are, in general, far too restrictive for image sequences of real world scenes. B.G. Schunck (1985, 86) recently argued that a constraint equation for the estimation of what he called image flow has to include a term containing the divergence of this image flow without presenting, however, a stringent derivation based on perspective projection from 3-D scene space. The present author derives a constraint equation based on a combination of perspective projection and notions from differential geometry. In addition, he demonstrates the quantitive effects of taking into account radiometric considerations based on the use of Lambertian reflection properties and isotropic illumination in scene space. >

Quantum-limited FM-spectroscopy with a lead-salt diode laser

Abstract: Ultrasensitive absorption spectroscopy of NO2 was performed with a tunable lead-salt diode laser (TDL) using a single-tone high-frequency modulation (FM) technique. With a detection bandwidth of 200 kHz, an optical density of 2.7 × 10−5 was detectable at SNR of 1. The detectable optical density could be further improved by reducing the detection bandwidth in agreement with the √Δf relationship, reaching 2.5 × 10−6 at a detection bandwidth of 1.56 kHz. Normalized to 1 Hz bandwidth, the demonstrated performance would then correspond to a detectable optical density of 5.9 × 10−8. This detection limit agrees well with the calculated “quantum limited” performance based on the measured laser power, modulation index, noise figure of the electronic components, and other parameters of the apparatus. These measurements and calculations show that by implementation of the FM technique, the sensitivity of the present TDL absorption spectrometers (TDLAS) can be improved by at least a factor of 10 and possibly even of 100. Such a sensitivity improvement would greatly extend the applicability of TDLAS for trace gas analysis, especially in atmospheric monitoring.

Applications of silicon microactuators based on bimorph structures

Abstract: Microactuators for electromechanical signal conversion are described. Basic elements of the transducer are a bimorph structure and an integrated heat source. Due to the differences of the coefficients of thermal expansion, a temperature-controlled deformation of the the bimorph structure occurs. Bulk and surface micromachining techniques can be used to achieve an object displacement perpendicular to or within the substrate plane. The main advantages of this class of actuators are simple fabrication processes and operation at standard IC (integrated circuit) voltage levels, allowing further system integration. The conversion characteristics are described, and the application of these transducers for microvalves, optical components, manipulators, and motors is discussed. >

Proliferation of fetal rat hepatocytes in response to growth factors and hormones in primary culture.

Abstract: Fetal rat hepatocytes (day 19 of gestation) multiply in primary culture in arginine-free, hydrocortisone-containing chemically defined medium MX-82 supplemented either with epidermal growth factor (EGF) or insulin or both. In contrast, hepatocytes did not multiply under similar culture conditions using Dulbecco's minimum essential medium (DMEM). Cells underwent two divisions within 10 days in cultures maintained in MX-82 medium without a medium change, and cells grew to increased final cell densities when the medium was renewed every third day. When the medium MX-82 was enriched by the addition of lipids, intermediary metabolites, and trace metals (medium MX-83), cells grew to higher densities. In the absence of the growth factors, cells became quiescent and subsequently could be induced to synthesize DNA in response to EGF. With the increasing numbers of cells per dish, the growth response of the hepatocytes diminished. Levels of hepatocyte-specific albumin and α-fetoprotein mRNAs at day 0 were similar to those observed at day 10 in primary fetal rat hepatocyte cultures and were maintained at higher levels in medium MX-83 than in medium MX-82.

Fluxes of atmospheric hydrogen sulphide to plant shoots

Abstract: Short-term exposure of maize, pumpkin, spinach and spruce to various atmospheric H2 S concentrations resulted in high H2 S fluxes to the shoots. In all species an almost linear relation was observed between flux and H2 S concentration up to around 0.3 μl -1 . At higher H2 S concentrations the flux reached a maximum, which was about 0.08, 0.04, 0.1 and 0.03 μmol g f. wt-1 h-1 for maize, pumpkin, spinach and spruce, respectively. The transpiration rate was not affected during H2 S exposure. Up to a level of 0.3 μl 1-1 , the shoot conductance for a influx of the various species varied between 61 and 92% of that predicted from shoot conductance for aqueous vapour efflux. There was no relation between the H2 S flux to the shoots and the sensitivity of the species towards H2 S. A 12 days' exposure of maize, pumpkin and spinach to 0.75 μl 1-1 H2 S resulted in a reduction of shoot yield of 1.36 and 69%, respectively. H2 S flux to the shoots of pumpkin, spinach and spruce remained rather constant during exposure for three or four days to about 0.22μl l-l H2 S. Even at a concentration of about 0.8 μl 1-1 H2 , which reduced the growth of pumpkin and spinach, the fluxes remained nearly constant. Fluxes of H2 S to the shoots did, however, vary diurnally, being high during the light and low during the dark period. The H2 S flux to transpiration ratio was constant during both light and dark periods, indicating that uptake was predominantly via the stomata. Only part of the total flux of H2 S to the shoots of pumpkin and spinach could be recovered in the water-soluble non-protein sulphydryl fraction of the shoots (maximum 34%). It is proposed that cysteine synthase is directly involved in the fixation and metabolism of atmospheric H2 S by the plant.

Wideband noise characteristics of a lead-salt diode laser: possibility of quantum noise limited TDLAS performance

Abstract: The wideband noise characteristics of a PbEuSe molecular beam epitaxy diode laser have been measured up to 500 MHz. The cutoff of the frequency dependent (1/f type) laser noise contribution was found to be 170 MHz for this particular laser. Above this cutoff frequency the photon shot noise dominates, as was demonstrated. A noise reduction of more than 2 orders of magnitude was observed in the shot noise limited domain when compared with the 1/f noise dominated region below 1 MHz. This finding indicates that a similar 2 orders of magnitude sensitivity improvement can be achieved in tunable diode laser absorption spectroscopy when frequency modulation techniques are applied instead of the more conventional derivative modulation below 1 MHz.

Recovery of sulfate transport into heterotrophic tobacco cells from inhibition by reduced glutathione

Abstract: In heterotrophic tobacco cells (Nicotiana tabacum L. cv. Samsun) inhibition of sulfate transport by reduced glutathione (GSH) is a reversible process. When GSH was removed from the culture medium subsequent to a 10-h treatment with 1 mM GSH, sulfate transport began to recover after a lag period of ca 4 h and reached the transport rates of controls without GSH within another 3–4 h. Recovery was prevented when inhibitors of protein synthesis, i.e. cycloheximide or puromycin, were added to the medium upon removal of GSH, even if low concentrations (cycloheximide 1 μM; puromycin 250 μM) were applied. At these low concentrations the rate of synthesis of sulfate transport entities was maintained at the rate of degradation in the absence of GSH. The post-transcriptional polyadenylation inhibitor cordycepin and the transcription inhibitor α-amanitin only slightly reduced recovery of sulfate transport from inhibition by GSH. Apparently, protein synthesis is required for this recovery, suggesting that inhibition of synthesis of sulfate carrier entities is the mechanism of action of GSH on sulfate transport in heterotrophic tobacco cells. An initial rate of net increase in sulfate transport during recovery from inhibition of GSH of 3.6±0.2 U h−1 was calculated [1 U=1 nmol sulfate (g DW)−1 min−1]. This rate of increase is small compared with the rate of decrease in sulfate transport at maximum inhibition by cycloheximide (110±3 U h−1). However, with increasing time of exposure without GSH, the net increase in sulfate transport was enhanced to a maximum rate of 96±3 U h−1, measured 5–7 h after GSH had been removed from the media. Apparently, the rate of synthesis of sulfate transport entities in heterotrophic tobacco cells is about twice its rate of degradation.

Investigation on the carcinogenic effects of various cadmium compounds after inhalation exposure in hamsters and mice.

Abstract: Summary The inhalation of cadmium chloride aerosols induced lung carcinomas in rats (3). Subsequently, CdCl 2 was classified as probably carcinogenic in humans (2). Thus the Cd compounds CdCl 2 , CdSO 4 , CdS and CdO were investigated for their carcinogenic potencies in the lungs of hamsters and mice. The same experiment was conducted by Glaser et al. whith rats (1).

Long‐term inhalation study with Wistar rats and four cadmium compounds

Abstract: In a previous long‐term inhalation study it was shown that by continuous exposure (23 hours per day, 7 days per week) to CdCl2 for one and a half years primary lung tumors were induced in male Wistar rats at Cd concentrations between 12.5 and 50 μg/m3. In these new extended experiments the carcinogenic result with CdCl2 was also verified for female rats and for either the water soluble aerosol Cd sulfate (CdSO4) or the insoluble compounds Cd sulfide (CdS) and Cd oxide (CdO) as dust and fume. The same types of primary lung tumors were determined histopathologically as in the previous study: benign and malignant adenomas, squamous cell carcinomas and combined forms. The lung tumor rates were rather high for all Cd compounds. At the Cd aerosol concentrations of 90 μg/m3 or more, the tumor rates decreased due to shorter inhalation periods for the water insoluble compounds. For these groups the inhalation times had to be reduced because of increased toxicity (lethality). But even if the inhalation periods last...

A Quantitative Theory of Laser-Generated Ultrasound

Abstract: The basic work of R. M. White [1] on the generation of elastic waves by transient surface heating was followed by numerous theoretical and experimental investigations, to understand the nature of the strange elastic waveforms obtained and to make this technique available for practical applications [2]. The theoretical considerations of L. R. F. Rose [3] about a point of dilation just below the surface of an elastic halfspace leads to a reasonable qualitative agreement with experiments, but do not relate all relevant material and laser beam parameters to the displacement field. This contributions outlines the application of an extended theory to a complete system of nondestructive evaluation, taking into account the structure of different laser modes, the optical, thermal and elastic material properties as well as the finite area of a capacitance transducer.

Profiles of Ozone and Surface Layer Parameters Over a Mature Spruce Stand

Abstract: Measurements of ozone profiles above a mature spruce stand lead to the conclusion that either an ozone production takes place close to or within the canopy or a destruction well above it, because at certain times a decrease of ozone with height has been observed. Possible influences of terpenes to this phenomenon are discussed. Fluxes and deposition velocities of ozone are calculated on the basis of the gradient approach. In addition, surface layer parameters and aerodynamic stand characteristics derived from wind velocity, temperature, and humidity profiles are presented.

Modified CORDIC algorithm with reduced iterations

Abstract: In this contribution we present a modified CORDIC algorithm that offers a considerable latency time reduction and chip area savings when compared with the original CORDIC method. The operations used are adds, shifts, and multiplication or division.

A self-calibration method for fast high-resolution A/D and D/A converters

Abstract: Monolithic analog-to-digital (A/D) and digital-to-analog (D/A) converters suffer from the limited accuracy of the available circuit compensators. A self-calibration method allows the correction of the linearity errors of binary-weighted current-source arrays commonly used in high-speed converters. To achieve high-calibration accuracy a modified dual-slope method is used. This makes it possible to implement A/D and D/A converters with a resolution of 14 b or more at a conversion time of less than 15 mu s. >

Realization of transmission-gate conditional-sum (TGCS) adders with low latency time

Abstract: Transmission conditional-sum (TGCS) adders realized in a standard 2.5- mu m CMOS technology are discussed. These adders offer short propagation delay and latency time (12.5 ns for 32-b addition) and consume only moderate chip area (i.e. 80*460 mu m/sup 2/ for 1 b in a 32-b adder). They allow static operation and consume only dynamic power (like standard CMOS). The layout exhibits high regularity and can be easily adjusted to various word lengths. Design and layout techniques are described in detail and experimental data are given. >

Lung response to test toner upon 2-year inhalation exposure in rats.

Abstract: Summary SPF F-344 rats were exposed 6 h/day 5 days/wk for up to 24 months to a special test toner at 0, 1, 4 and 16 mg/m3 or TiO2 at 5 mg/m3, or SiO2 at 1 mg/m3, by the inhalation route. The animals were kept for an additional 6 weeks in filtered air. Surviving animals were sacrificed at 25.5 months after start of exposure. Life-span and causes of death were independent of treatment and in accordance with published values. No evidence for systemic toxicity or any upper-respiratory system effects were found in the toner-exposed groups. The incidence of lung tumors was comparable in the control, 3 toner and TiO2-exposed groups. An incidence of 18%, combined benign and malignant tumors was observed in the quartz-treated rats. A slight to moderate degree of fibrosis was observed at the toner high exposure level in all animals, while a very slight degree of fibrosis was noted in 20% of the animals at the toner middle (4 mg/m3) exposure level. The fibrogenic potency of the test toner was calculated to be comparable to TiO2. No pulmonary changes were seen at the toner low (1 mg/m3) and environmentally most relevant exposure level.

MESFETs in thin silicon on SIMOX

Abstract: Si MESFETs have been built into a thin (100nm) Si film on buried oxide implanted wafers Aluminium has been used as gate material to obtain process compatibility with a highperformance CMOS process With appropriate back bias the normally-on devices become enhancement-type The highquality SIMOX substrate provides excellent transconductance, while the thin film reduces two-dimensional effects

JFET-CMOS microstrip front-end

Abstract: While the CMOS version of the front-end chip developed for the microstrip vertex detector of the Aleph experiment is ready to go into operation, a new development is being carried on to achieve a reduction in noise. The improvement is related to the use of a JFET-CMOS chip design which is described in the present paper.

Efficient generation of acoustic pressure waves by short laser pulses

Abstract: The displacement of laser-generated ultrasonic bulk waves in polycrystalline metal samples consists of signals travelling with pressure wave velocity as well as with shear wave velocity. The waveform obtained depends on the incident laser power density and the laser energy. It is found that there is a specific power density I 0 at which only a maximum pressure pulse is generated whose magnitude is proportional to the laser energy. Furthermore, the angular distribution of the pressure pulse shows that most of the acoustic energy is radiated in the forward direction. The Fourier spectrum of the pressure pulse is also evaluated.

Mouse interferon-gamma in liposomes: pharmacokinetics, organ-distribution, and activation of spleen and liver macrophages in vivo.

Abstract: Recombinant mouse interferon-gamma (IFN-gamma) was encapsulated into multilamellar vesicles and the proportion of encapsulated IFN-gamma determined by biological activity was 19%. The distribution of 125I-labeled IFN-gamma liposomes in C57BL/6 mice was analyzed. After an initial enrichment of liposomes in lung, more than 60% of total 125I-labeled IFN-gamma was accumulated in spleen and liver. Furthermore, it was observed if the encapsulation of IFN-gamma in liposomes prevented the rapid decay of IFN-gamma in serum of C57BL/6 mice after intravenous injection. We compared the serum decay curve of liposomal and free IFN-gamma, and showed that IFN-gamma encapsulated in liposomes has an elongated availability in the serum. In addition, we established that a combination of 10(2) U/ml IFN-gamma and 1 microgram/ml MTP-PE, encapsulated in liposomes, activates splenic and starch-elicited peritoneal macrophages in vitro synergistically to kill Leishmania donovani promastigotes. After intravenous injection of liposomal IFN-gamma (5 X 10(3) U) and muramyltripeptide (MTP-PE) (6 micrograms) in C57BL/6 mice, splenic and liver macrophages were activated in vivo to kill Leishmania species in vitro. Neither an injection of the same amount of free substances nor injection of empty liposomes resulted in an increased leishmanicidal activity.

Hough transform using Cordic method

Abstract: The purpose of the letter is to demonstrate the usefulness of the Cordic algorithm for implementation of image processing algorithms in dedicated hardware to achieve near real-time processing speed. The Cordic algorithm will be discussed, and also its application for line and circle detection as well as for arbitrary shapes using Hough transforms.

Investigation of a potential cotumorigenic effect of the dioxides of nitrogen and sulfur, and of diesel-engine exhaust, on the respiratory tract of Syrian golden hamsters.

Abstract: Syrian golden hamsters (480 males and 480 females) allocated into 24 groups were exposed 19 hours per day and 5 days per week for 6, 10.5, 15, or 18 months to total diesel exhaust, diesel exhaust without particles, a mixture of nitrogen dioxide (5 parts per million (ppm)2) and sulfur dioxide (10 ppm), or clean air. Two exposure groups from each test atmosphere were also treated by a single subcutaneous injection of either 3 mg or 6 mg of diethylnitrosamine/kg of body weight to evaluate an enhancing effect of diethylnitrosamine on exposure-related changes. Morphological evaluation was done by histopathology. Minor changes of the larynx and trachea were investigated by scanning electron microscopy, which showed a loss of ciliated cells in all exhaust-exposed groups. After exposure to diesel exhaust with or without particles, focal metaplasia and dysplasia of the respiratory epithelium were seen in the oldest animals by scanning electron microscopy. In the same specimens, attached mucous droplets indicated changes in mucous cells and mucous viscosity. Only the exposure to total diesel exhaust significantly increased the tumor rate in the upper respiratory tract of male hamsters treated with 6 mg of diethylnitrosamine per kg of body weight. At the lower diethylnitrosaminemore » dose, no exposure-related effects on the tumor rates could be observed. The results from this study and from our other inhalation experiments appear to be insufficiently conclusive to demonstrate that diesel-engine exhaust should be classified as a cocarcinogen or enhancer for the test system used.« less