Showing papers by "École Polytechnique Fédérale de Lausanne published in 1984"
TL;DR: The rapidity and ease of performance as well as the low costs of the test necessitate a high priority for validation of this promising Drosophila short-term test.
Abstract: A novel test system for the detection of mutagenic and recombinogenic activity of chemicals is described in detail. Drosophila melanogaster larvae trans-heterozygous for the mutations multiple wing hairs (mwh) and flare (flr) are exposed to the test compounds for various periods of time ranging from 96 hr to 1 hr. Induced mutations are detected as single mosaic spots on the wing blade of surviving adults that show either the multiple wing hairs or flare phenotype. Induced recombination leads to mwh and flr twin spots and also to a certain extent, to mwh single spots. Recording of the frequency and the size of the different spots allows for a quantitative determination of the mutagenic and recombinogenic effects. This and earlier studies with a small set of well-known mutagens indicate that the test detects monofunctional and polyfunctional alkylating agents (ethyl methanesulfonate, diepoxybutane, mitomycin C, Trenimon), mutagens forming large adducts (aflatoxin B1), DNA breaking agents (bleomycin), intercalating agents (5-aminoacridine, ICR-170), spindle poisons (vinblastine), and antimetabolites (methotrexate). In addition, the test detects mutagens unstable in aqueous solution (beta-propiolactone), gaseous mutagens (1,2-dibromoethane), as well as promutagens needing various pathways of metabolic activation (aflatoxin B1, diethylnitrosamine, dimethylnitrosamine, mitomycin C, and procarbazine). The rapidity and ease of performance as well as the low costs of the test necessitate a high priority for validation of this promising Drosophila short-term test.
641 citations
TL;DR: A parallel implementation, based on pseudo-QMF filters, is presented as an efficient way to split a signal into equal sub-bands.
531 citations
TL;DR: In this article, a growth equation for free dendrites growing in a liquid alloy was developed by coupling their diffusion fields for a parabolic tip and by applying a stability criterion.
454 citations
TL;DR: A simple algorithm for the evaluation of discrete Fourier transforms (DFT) and discrete cosine transforms (DCT) is presented, which achieves a substantial decrease in the number of additions when compared to currently used FFT algorithms.
366 citations
TL;DR: The photo-oxygenation of furfuryl alcohol (FFA) in water sensitized by naturally occurring dissolved organic materials under visible light is shown to proceed almost exclusively by a singlet oxygen mechanism.
354 citations
TL;DR: Results indicate that a 9-bit matching accuracy can be obtained for capacitors and an 8-bit accuracy for MOS current sources without difficulty if the systematic error sources are reduced using proper design and layout techniques.
Abstract: Explicit formulas are derived using statistical methods for the random errors affecting capacitance and current ratios in MOS integrated circuits. They give the dependence of each error source on the physical dimensions, the standard deviations of the fabrication parameters, the bias conditions, etc. Experimental results, obtained for both matched capacitors and matched current sources using a 3.5-/spl mu/m NMOS technology, confirmed the theoretical predictions. Random effects represent the ultimate limitation on the achievable accuracy of switched-capacitor filters, D/A converters, and other MOS analog integrated circuits. The results indicate that a 9-bit matching accuracy can be obtained for capacitors and an 8-bit accuracy for MOS current sources without difficulty if the systematic error sources are reduced using proper design and layout techniques.
339 citations
TL;DR: In the absence of catalysts, homogeneous Mn(II) solutions that are not oversaturated with respect to MnCO3 or Mn(OH)2, remain in the presence of dissolved oxygen unoxidized for periods in excess of seven years as discussed by the authors.
286 citations
[...]
TL;DR: In this paper, a rather general theory of friction, inspired from the classical theory of plasticity, is proposed, which includes the contact impenetrability condition as a by-product.
202 citations
[...]
TL;DR: This poster presents a probabilistic procedure for determining the carrier and removal of canine coronavirus from the blood stream through a simple, straightforward, and efficient procedure called “catch-and-catch” surgery.
202 citations
TL;DR: This work derived theoretically the ultimate sensitivity limits of the grating devices employed either as switches or as gas sensors, and demonstrated new switching and gas-sensing effects in integrated optics using input and output grating couplers and Bragg reflector gratings with 1200 lines/mm on planar SiO-TiO(2) waveguides.
Abstract: We have demonstrated new switching and gas-sensing effects in integrated optics using input and output grating couplers and Bragg reflector gratings with 1200 lines/mm on planar SiO2–TiO2 waveguides. Switching is actuated by adsorption or desorption of water or other adsorbates on the waveguide surface through a change in the effective index of the guided modes under the grating. We derived theoretically the ultimate sensitivity limits of the grating devices employed either as switches or as gas sensors. Switching requires the adsorption and desorption, respectively, of less than one H2O monolayer. Sensors can detect variations in surface coverage of 1/100 of an H2O monolayer.
161 citations
TL;DR: In this paper, selectivities were measured for membrane electrodes containing a given amount of a neutral carrier (ETH 1692) and varying amounts of the additive potassium tetrakis( p -chlorophenyl)borate.
TL;DR: In this paper, the double torsion test technique was used to investigate the fracture properties of two commercial epoxide resins filled with glass beads, and the influence of varying the volume fraction of glass, the mean particle size and the pre-treatment of the glass surface on the stress intensity factor have been determined.
Abstract: The double torsion test technique was used to investigate the fracture properties of two commercial epoxide resins filled with glass beads. The influence of varying the volume fraction of glass, the mean particle size and the pre-treatment of the glass surface on the stress intensity factor have been determined. A correlation has been found between the compressive yield strength and the stability of fracture in these composites, similar to that found for unfilled epoxide resins.
TL;DR: The thylakoid membrane of Rhodopseudomonas viridis contains extensive, regular arrays of photoreceptor complexes arranged on a hexagonal lattice with a repeat distance of ˜130 Å, indicating a strong asymmetry of the membrane.
Abstract: The thylakoid membrane of Rhodopseudomonas viridis contains extensive, regular arrays of photoreceptor complexes arranged on a hexagonal lattice with a repeat distance of ˜130 A. Single membrane sheets were obtained by mild treatment of the thylakoid fraction with the detergent Triton X-100. Heavy metal shadowing and electron microscopy of isolated thylakoids indicated a strong asymmetry of the membrane, showing a smooth plasmic and a rough exoplasmic side. Fourier processing of rotary-shadowed specimens showed the different surface relief on both sides of the membrane. Structural units on both sides were roughly circular and showed 6-fold symmetry at a resolution close to 20 A. The structural unit was characterised by a central core that seemed to extend through the membrane, protruding on the exoplasmic side. The core was surrounded by a ring showing 12 subunits on the plasmic side. Rotary-shadowed as well as negatively-stained membranes indicated a handedness of the structure. Treatment of thylakoid vesicles with higher detergent concentrations yielded a fraction of particles showing the same features as Fourier maps of the structural units. The isolated particles therefore appeared to represent structurally intact units of photosynthesis.
01 Jan 1984
TL;DR: New quadrature mirror filter structures for the frequency domain analysis and synthesis of digital signals are introduced and a new scheme which reduces the computational complexity by about a factor of two over conventional QMF implementations is proposed.
Abstract: This paper introduces new quadrature mirror filter (QMF) structures for the frequency domain analysis and synthesis of digital signals. The conventional QMF technique is first extended to cover complex quadrature mirror filters (CQMF) in which a digital signal is split into N adjacent complex subbands where the real and imaginary parts are subsampled by 1/2N with respect to the original signal. The computational complexity of QMF banks is then analyzed and a new scheme which reduces the computational complexity by about a factor of two over conventional QMF implementations is proposed. Finally, the filter design tradeoffs are discussed and the microprogramed implementation of QMF banks is evaluated.
TL;DR: In this paper, the reaction of triorganyl(dimethylamino)silanes with surface-hydrated silicon dioxide has been studied and shown to yield a dense grafted layer.
Abstract: The reaction of triorganyl(dimethylamino)silanes with surface-hydrated silicon dioxide has been studied. These silylating agents are easy to prepare from the corresponding chloro or bromosilanes with dimethylamine. The resulting products are thermally stable and relatively volatile. Reaction with surface-hydrated silicon-dioxide preparations at 150–250°C for 170 h yields a dense grafted layer. However, with (dimethylamino)silanes having strongly polar substituents, a retreatment of the surface-modified silica seems to be necessary in order to attain maximum coverage.
TL;DR: In this article, the authors showed that assuming a constant quantum yield measured at a short wavelength can overestimate the 1O2 concentration in sunlit surface waters by more than a factor of 2.
TL;DR: In this paper, the accumulation of sediments, trace metals and hydrocarbons has been estimated from the analysis of the sediment from six coring sites in Narragansett Bay.
Abstract: The accumulation of sediments, trace metals and hydrocarbons has been estimated from the analysis of the sediment from six coring sites in Narragansett Bay. Radionuclides ( 234 Th xs , 210 Pb xs , 239,240 Pu) with known input functions and trace metals (Cu, Pb) were used. We estimate that 6·9 × 10 4 tons of sediments, 51–90 tons of Pb, 72–100 tons of Cu and 400–1000 tons of total hydrocarbons accumulate annually under present conditions in the bay. This represents 64–117% (Pb), 89–123% (Cu) and 23–58% (hydrocarbons), respectively, of present day inputs to the bay. Furthermore, close to 100% of the particle-reactive radionuclides 210 Pb and 239,240 Pu accumulate in the bay. Present day inputs to the bay were calculated independently as 77–80 tons Pb and 81 tons of Cu. Sewage effluents were the dominant source of Cu, whereas atmospheric deposition and urban runoff were most important for Pb. Dredging activities by the U.S. Army Corps of Engineers between 1946 and 1971 removed more sediments from the bay than would have accumulated during the same time in the undredged areas of the bay. Copper smelting and coal mining on the shores of the upper bay during 1866–1880 left an imprint in the sediments which is still evident. Model derived accumulation rates of Pb, Cu and coal during that time were 3–4 times present-day inputs.
TL;DR: In this article, a series of 15 anion-selective membranes, based on quaternary ammonium compounds of different constitution and on a variety of plasticizers in different compositions of the solvent polymeric membranes, lead throughout to the selectivity sequence.
Abstract: A series of 15 anion-selective membranes, based on quaternary ammonium compounds of different constitution and on a variety of plasticizers in different compositions of the solvent polymeric membranes, lead throughout to the selectivity sequence
$$ClO_4 - > SCN - > I - > NO_3 - > Br - > Cl - > HCO_3 - \sim OAc - \sim SO_4 ^2 - \sim HPO_4 ^2 - .$$
. A detailed analysis demonstrates that the selectivity pattern of such systems may be drastically modified only if
TL;DR: Dicyclohexylcarbodiimide, a classical inhibitor of the F1Fo-ATPase, has recently been found to covalently interact and thereby inhibit a number of other enzymes involved in proton translocation across biological membranes.
TL;DR: Utilisation de l'alcool nitro-3 benzylique comme matrice lors des spectres de masse FAB en particulier de la cyclosporine A et de la valinomycine as discussed by the authors.
Abstract: Utilisation de l'alcool nitro-3 benzylique comme matrice lors des spectres de masse FAB en particulier de la cyclosporine A et de la valinomycine
TL;DR: In this article, the deformation mechanism of concentrated alloys up to 550 K was characterized using conventional straining tests, together with in situ deformation experiments in a high voltage electron microscope.
TL;DR: The bovine serum albumin sorption behavior of polymethyl methacrylate nanoparticles was followed under various conditions, and adsorption was found to increase with increasing protein concentration and increasing temperature, reaching a maximum at the isoelectric point of pH 4.9 after approximately 12 h of incubation.
TL;DR: The results are interpreted to indicate that some kind of an induction or activation mechanism is involved in both dye decolorization and lignin degradation in P. chrysosporium.
TL;DR: In this article, the evolution of the structure and local effective stresses with strain has been identified by electron microscopy by pinning the dislocations under load in an Al-Zn alloy.
TL;DR: From an analysis of dynamic and steady‐state experiments, two control systems for carbon dioxide production rate control during the continuous culture of baker's yeast have been designed and evaluated experimentally and provide a means to indirectly optimize biomass production while preventing ethanol formation.
Abstract: Based on the material balance principle applied to microbial reactions in continuous bioprocesses, the concept of reaction rate control has been developed theoretically. This concept provides a more direct way of controlling biological activities than the control of physical or chemical parameters in practice today. From an analysis of dynamic and steady-state experiments, two control systems for carbon dioxide production rate control during the continuous culture of baker's yeast have been designed and evaluated experimentally. In these control methods, intracellular NADH concentration is used as an immediate indication of the onset of glucose repression. A more sophisticated master controller based on the respiratory quotient can be combined with these control methods. The resulting control system provides a means to indirectly optimize biomass production while preventing ethanol formation in the continuous culture of baker's yeast.
TL;DR: Ethanol in the dose of 0.7 g/kg intensified cigarette smoking of the second cigarette by increasing delta tidal CO, average puff volume, and total puff volume per cigarette, whereas caffeine given alone or combined with ethanol failed to influence puffing behavior consistently.
Abstract: Puffing behavior (number of puffs, puff duration, puff volume, peak pressure, peak flow, peak latency, and puff interval) and pre- to postsmoking Δ tidal CO difference were measured in female subjects in order to assess separate and combined effects of ethanol and caffeine. The subjects smoked two cigarettes of their habitual brand in a preliminary familiarizing session and in each of the subsequent four test sessions. The treatments administered after smoking the first cigarette in the test sessions were: alcohol placebo and caffeine placebo; alcohol placebo and caffeine; alcohol and caffeine placebo; alcohol and caffeine. Test-retest reliability across the first cigarette of each session (which was not smoked under the influence of the treatments) was remarkably high for all the puffing parameters. Ethanol in the dose of 0.7 g/kg intensified cigarette smoking of the second cigarette by increasing Δ tidal CO, average puff volume, and total puff volume per cigarette, whereas 0.5 g/kg ethanol and 5 mg/kg caffeine given alone or combined with ethanol failed to influence puffing behavior consistently.
TL;DR: In this paper, the authors investigated the luminescence of 7-azaindole (7AI) in non-polar solvents and alcohols with respect to its dependence upon temperature, concentration, and excitation energy.
TL;DR: Veratryl alcohol, a natural secondary metabolite of P. chrysosporium, also activated the lignin-degrading system as mentioned in this paper, which was connected to increased H2O2 production and glucose oxidation rates.
01 Jan 1984
TL;DR: Flow in channel branches and bends is analysed by using elementary hydraulic theory to explore the simplified flow processes in the two flow elements using expressions for the local loss coefficients.
Abstract: Flow in channel branches and bends is analysed by using elementary hydraulic theory. The results are expressions for the local loss coefficients. The primary purpose is to explore the simplified fl...