Showing papers by "University of Patras published in 1995"
TL;DR: In this article, a study of contact metric manifolds for which the characteristic vector field of the contact structure satisfies a nullity type condition, condition (*) below, is presented.
Abstract: This paper presents a study of contact metric manifolds for which the characteristic vector field of the contact structure satisfies a nullity type condition, condition (*) below. There are a number of reasons for studying this condition and results concerning it given in the paper: There exist examples in all dimensions; the condition is invariant underD-homothetic deformations; in dimensions>5 the condition determines the curvature completely; and in dimension 3 a complete, classification is given, in particular these include the 3-dimensional unimodular Lie groups with a left invariant metric.
325 citations
TL;DR: In this paper, a model pore network of the chamber-and-throat type, etched in glass, was used to determine the flow regimes, and to calculate the corresponding relative permeabilities and fractional flow values.
Abstract: Steady-state two-phase flow in porous media was studied experimentally, using a model pore network of the chamber-and-throat type, etched in glass. The size of the network was sufficient to make end effects negligible. The capillary number, Cu, the flow-rate ratio, Y, and the viscosity ratio, K, were changed systematically in a range that is of practical interest, whereas the wettability (moderate), the coalescence factor (high), and the geometrical and topological parameters of the porous medium were kept constant. Optical observations and macroscopic measurements were used to determine the flow regimes, and to calculate the corresponding relative permeabilities and fractional flow values. Four main flow regimes were observed and videorecorded, namely large-ganglion dynamics (LGD), small-ganglion dynamics (SGD), drop-traffic flow (DTF) and connected pathway flow (CPF). A map of the flow regimes is given in figure 3. The experimental demonstration that LGD, SGD and DTF prevail under flow conditions of practical interest, for which the widely held dogma presumes connected pathway flow, necessitates the drastic modification of that assumption. This is bound to have profound implications for the mathematical analysis and computer simulation of the process. The relative permeabilities are shown to correlate strongly with the flow regimes, figure 1 1. The relative permeability to oil (non-wetting fluid), k,,, is minimal in the domain of LGD, and increases strongly as the flow mechanism changes from LGD to SGD to DTF to CPF. The relative permeability to water (wetting fluid), k,,, is minimal in the domain of SGD; it increases moderately as the flow mechanism changes from SGD to LGD, whereas it increases strongly as the mechanism changes from SGD to DTF to CPF. Qualitative mechanistic explanations for these experimental results are proposed. The conventional relative permeabilities and the fractional flow of water,f,, are found to be strong functions not only of the water saturation, S,, but also of Cu and K (with the wettability, the coalescence factor, and all the other parameters kept constant). These results imply that a fundamental reconsideration of fractional flow theory is warranted.
277 citations
TL;DR: It may be concluded that P. fruticosa leaves avoid severe photoinhibitory and oxidative damage during the long, warm, dry and sunny Mediterranean summer by reducing light harvesting and electron flow capacity, whilst maintaining an adequate photoprotective ability.
Abstract: Photosynthetic pigments and relative water content of young leaves of P. fruticosa decreased considerably with the onset of the summer dry period and stabilized at low values for the last two summer months, while leaf growth was arrested. Corresponding decreases in photochemical efficiency of photosystem II, as judged by chlorophyll fluorescence measurements of predarkened leaves, were, however, negligible. Following the first autumn heavy rains, growth was restored and photosynthetic pigments and relative water content increased to the pre-drought values. The results indicate that the reduction of chlorophylls does not result from severe photoinhibitory damage but, instead, it may be an adaptive response against the adverse conditions of the Mediterranean summer. Some photosynthetic and photoprotective characteristics of P. fruticosa leaves at two stages of their development, i.e. at the severely dehydrated state with arrested growth during late summer and after their revival following the first heavy autumn rains were compared. Apart from the chlorophyll loss, the photon yield of O 2 evolution and the photosynthetic capacity at saturated CO 2 were considerably suppressed during the summer, indicating that the extremely low net photosynthetic rates observed in the field were the combined result of stomatal and mesophyll limitations. Epoxidation state was low at midday during the summer, indicating an active, photodissipative xanthophyll cycle. Although zeaxanthin content did not increase at midday after the rains, the potential of the cycle was maintained in the revived leaves, as judged by the high concentrations of the cycle components. After the rains, the activities of the anti-oxidant enzymes (superoxide dismutase, ascorbate peroxidase) remained relatively unchanged on a chlorophyll basis, but increased when expressed on a leaf surface area or protein basis. It may be concluded that P. fruticosa leaves avoid severe photoinhibitory and oxidative damage during the long, warm, dry and sunny Mediterranean summer by reducing light harvesting and electron flow capacity, whilst maintaining an adequate photoprotective ability. The preservation of a remarkable photodissipative and anti-oxidative potential after the rains may be related to the low predictability of precipitation even during the rainy winter.
231 citations
TL;DR: The results indicate that ISMN and ISDN inhibit angiogenesis and tumour growth and metastasis in an animal tumour model, and it is considered that these nitrovasodilators which are widely used therapeutically and have well characterized pharmacological profiles, may also possess antitumour properties in the clinic.
Abstract: 1. The effect of the nitric oxide (NO)-producing nitrovasodilators isosorbide mononitrate (ISMN) and isosorbide dinitrate (ISDN) were assessed on (a) the in vivo model of angiogenesis of the chick chorioallantoic membrane (CAM) and (b) on the growth and metastatic properties of the Lewis Lung carcinoma (LLC) in mice. 2. Isosorbide 5-mononitrate (ISMN) and isosorbide dinitrate (ISDN), inhibited angiogenesis in the CAM dose-dependently. ISMN was more potent in inhibiting this process. Both compounds were capable of completely reversing the angiogenic effect of alpha-thrombin. These effects of ISMN and ISDN on angiogenesis were comparable to those previously observed with sodium nitroprusside which generates NO non-enzymatically. 3. Mice, implanted intramuscularly with LLC, received daily i.p. injections of ISMN for 14 days resulting in a significant decrease in the size of the primary tumour and a reduction in the number and size of metastatic foci in the lungs. ISDN had a similar but less pronounced effect than that observed with ISMN. 4. Addition of ISMN or ISDN to cultures of bovine, rabbit and human endothelial cells and to cultures of LLC cells had no effect on their growth characteristics. 5. These results indicate that ISMN and ISDN inhibit angiogenesis and tumor growth and metastasis in an animal tumour model. The possibility should therefore be considered that these nitrovasodilators which are widely used therapeutically and have well characterized pharmacological profiles, may also possess antitumour properties in the clinic.
167 citations
TL;DR: In this article, the authors present an up-to-date literature survey on the dynamics of underground structures and present numerical examples involving lined cavities and long lined tunnels buried in the full- or the half-space subjected to external forces or seismic waves.
Abstract: An up to date literature survey on the dynamics of underground structures is presented briefly. The dynamic response of large three-dimensional underground structures to external or internal dynamic forces or to seismic waves is numerically determined by the frequency domain boundary element method. This method is used to model both the structure and the soil medium, which are assumed to behave as linear elastic or viscoelastic bodies. The full-space dynamic fundamental solution is employed in the formulation and this requires a free soil surface discretization, confined to a finite portion around the area of interest, in addition to soil—structure interface and free structural surface discretizations. The dynamic disturbances can have a harmonic or a transient time variation. The transient case is treated with the aid of numerical Laplace transforms with respect to time. Various numerical examples involving lined cavities and long lined tunnels buried in the full- or the half-space subjected to harmonic or transient external forces or seismic waves are presented to illustrate the method and demonstrate its advantages.
124 citations
TL;DR: It was found that the contribution of the polar interactions to the energy of interaction at the solid-liquid interface increases with the glassy phase content of the oxide that causes reduction of the measured contact angle.
Abstract: Wetting experiments, by the sessile drop technique, were carried out at 37°C in air to determine the surface and interfacial interactions that take place in various solid bioceramics based on Al2O3, ZrO2(YPZ), SiO2, and TiO2 in contact with water, Ringer solution, artificial synovial fluid, calf serum, human plasma, and whole blood (+ EDTA). The surface energy of the liquids was measured by the ring method. The calculated values of the energy of interaction (work of adhesion) reveal that intermolecular forces act across the solid-liquid interfaces. The contribution of the dispersion and polar interactions to the surface energy of the polar liquids and the pure or mixed oxides was determined assuming that in the system of Mn-steel-liquids only dispersion forces act at the interface. It was found that the contribution of the polar interactions to the energy of interaction at the solid-liquid interface increases with the glassy phase content of the oxide that causes reduction of the measured contact angle. © 1995 John Wiley & Sons, Inc.
121 citations
TL;DR: In this article, the effect of temperature-dependent viscosity on an incompressible fluid in steady laminar free-forced convective boundary layer flow over an isothermal vertical semi-infinite flat plate is studied.
Abstract: The effect of a temperature-dependent viscosity on an incompressible fluid in steady laminar free-forced convective boundary layer flow over an isothermal vertical semi-infinite flat plate is studied. The local similarity solution is used to transform the system of partial differential equations, describing the problem under consideration, into a boundary value problem of coupled ordinary differential equations and an efficient numerical technique is implemented to solve the reduced system. Numerical calculations are carried out, for various values of the dimensionless parameters of the problem, which include a Prandtl number, a mixed convection parameter and a viscosity/temperature parameter. The results are presented graphically and the conclusion is drawn that the flow field and other quantities of physical interest are significantly influenced by these parameters. In particular, it is concluded that when the viscosity of a working fluid is sensitive to the variation of temperature, care must be taken to include this effect, otherwise considerable error can result in the heat transfer processes. In the literature, such care is not always evident.
118 citations
TL;DR: In this paper, the efficiency of four different compatibilizers melt-mixed with a poly(ethylene terephthalate)/high density polyethylene (PET/HDPE) blend was investigated.
114 citations
Journal Article•
TL;DR: Five language and tagset independent stochastic taggers, handling morphological and contextual information, are presented and tested in corpora of seven European languages, using two sets of grammatical tags, and it is shown that the taggers' performance is satisfactory, even though a small training text is available.
Abstract: Five language and tagset independent stochastic taggers, handling morphological and contextual information, are presented and tested in corpora of seven European languages (Dutch, English, French, German, Greek, Italian and Spanish), using two sets of grammatical tags; a small set containing the eleven main grammatical classes and a large set of grammatical categories common to all languages. The unknown words are tagged using an experimentally proven stochastic hypothesis that links the stochastic behavior of the unknown words with that of the less probable known words. A fully automatic training and tagging program has been implemented on an IBM PC-compatible 80386-based computer. Measurements of error rate, time response, and memory requirements have shown that the taggers' performance is satisfactory, even though a small training text is available. The error rate is improved when new texts are used to update the stochastic model parameters.
110 citations
TL;DR: In this paper, a post-tensioning metal strips around reinforced concrete columns, by using a strapping machine, are used to increase member strength and ductility to higher levels than those possible by conventional reinforcement.
103 citations
TL;DR: In this paper, a parametric experimental investigation of the coupling effects during steady-state two-phase flow in porous media was carried out using a large model pore network of the chamber-and-throat type, etched in glass.
Abstract: A parametric experimental investigation of the coupling effects during steady-state two-phase flow in porous media was carried out using a large model pore network of the chamber-and-throat type, etched in glass. The wetting phase saturation, S 1, the capillary number, Ca, and the viscosity ratio, κ, were changed systematically, whereas the wettability (contact angle θ e ), the coalescence factor Co, and the geometrical and topological parameters were kept constant. The fluid flow rate and the pressure drop were measured independently for each fluid. During each experiment, the pore-scale flow mechanisms were observed and videorecorded, and the mean water saturation was determined with image analysis. Conventional relative permeability, as well as generalized relative permeability coefficients (with the viscous coupling terms taken explicitly into account) were determined with a new method that is based on a B-spline functional representation combined with standard constrained optimization techniques. A simple relationship between the conventional relative permeabilities and the generalized relative permeability coefficients is established based on several experimental sets. The viscous coupling (off-diagonal) coefficients are found to be comparable in magnitude to the direct (diagonal) coefficients over board ranges of the flow parameter values. The off-diagonal coefficients (k rij /μ j ) are found to be unequal, and this is explained by the fact that, in the class of flows under consideration, microscopic reversibility does not hold and thus the Onsager—Casimir reciprocal relation does not apply. The coupling indices are introduced here; they are defined so that the magnitude of each coupling index is the measure of the contribution of the coupling effects to the flow rate of the corresponding fluid. A correlation of the coupling indices with the underlying flow mechanisms and the pertinent flow parameters is established.
TL;DR: A complementary DNA clone derived from the medfly white gene was isolated, which showed substantial similarity to white genes in Drosophila melanogaster and other Diptera, and can be used to restore partial eye color in transgenic Dosophila carrying a null mutation in the endogenous white gene.
Abstract: Reliable germline transformation is required for molecular studies and ultimately for genetic control of economically important insects, such as the Mediterranean fruit fly (medfly) Ceratitis capitata. A prerequisite for the establishment and maintenance of transformant lines is selectable or phenotypically dominant markers. To this end, a complementary DNA clone derived from the medfly white gene was isolated, which showed substantial similarity to white genes in Drosophila melanogaster and other Diptera. It is correlated with a spontaneous mutation causing white eyes in the medfly and can be used to restore partial eye color in transgenic Drosophila carrying a null mutation in the endogenous white gene.
TL;DR: The effects of enhanced UV-B (290-320 nm) radiation on two native Mediterranean pines (Pinus pinea L., Pinus halepensis Mill) were recorded during a one-year field study as discussed by the authors.
Abstract: The effects of enhanced UV-B (290-320 nm) radiation on two native Mediterranean pines (Pinus pinea L., Pinus halepensis Mill.) were recorded during a one-year field study. Plants received ambient or ambient plus supplemental UV-B radiation (simulating a 15% stratospheric ozone depletion over Patras, Greece, 38.3 o N, 29.1 o E) and only natural precipitation, i.e. they were simultaneously exposed to other natural stresses, particularly water stress during summer. Supplemental UV-B irradiation started in early February, 1993 and up to late June, no effects were observed on growth and photochemical efficiency of photosystem II, as measured by chlorophyll fluorescence induction. Water stress during the summer was manifested in the control plants as a decline in the ratio of variable to maximum fluorescence (F v /F m ), the apparent photon yield for oxygen evolution (Φ i ) and the photosynthetic capacity at 5% CO 2 (P m ). In addition, a partial needle loss was evident. Under supplemental UV-B radiation, however, the decreases in F v /F m , Φ i , and P m , as well as needle losses were significantly less. Soon after the first heavy autumn rains, photosynthetic parameters in both control and UV-B treated plants recovered to similar values, but the transient summer superiority of UV-B irradiated plants resulted in a significant increase in their dry weight measured at plant harvest, during late January, 1994. Plant height, UV-B absorbing compounds, photosynthetic pigments and relative water content measured at late spring, late summer and at plant harvest, were not significantly affected by supplemental UV-B radiation. The results indicate that enhanced UV-B radiation may be beneficial for Mediterranean pines through a partial alleviation of the adverse effects of summer drought
TL;DR: A rapid, highly sensitive and reproducible HPCE method is described for the determination of all non- and variously sulphated disaccharides present in hyaluronan and vertebrate chondroitin sulphates and dermatan sulphates.
TL;DR: Amphiphilic heteroarm star copolymers bearing polystyrene (PS) and poly(ethylene oxide) branches have been synthesized by sequential anionic living copolymerization.
Journal Article•
TL;DR: The results suggest that young SLE patients exhibit a "premature aging" of the inner ear which eventually stabilizes and there is a regular decrease in acuity in all groups (except for the elderly patients: 60-69), which may indicate a subclinical vestibular hydrops.
Abstract: Objective Hearing abnormalities have been described in several connective tissue diseases, but relevant data in systemic lupus erythematosus (SLE) is very insufficient. We therefore prospectively evaluated forty unselected consecutive female SLE patients for evidence of audiovestibular dysfunction and compared the results with those of 65 age-matched healthy women. Methods Patients and controls were separated into five age groups, i.e. 16-29 years, 30-39, 40-49, 50-59 and 60-69 years. Evaluation included pure tone audiometry thresholds at octave frequencies from 125Hz to 8000Hz, tympanometry and the stapedial reflex test in both ears. In particular, SLE activity, the presence of vasculitis and severe kidney and nervous system involvement, and serum levels of anti-ds-DNA antibodies and C3 and C4 were recorded. Results A statistically significant decrease in hearing acuity at low frequencies (125-500Hz) was found in the patients aged 16-59 compared with the controls, whereas in the first group of young patients (16-29) a similar decrease was observed in the high frequencies as well. No correlation was found between these abnormalities and any parameter of the underlying disease. Conclusion With regard to the high frequencies, our results suggest that young SLE patients exhibit a "premature aging" of the inner ear which eventually stabilizes. On the contrary, at low frequencies there is a regular decrease in acuity in all groups (except for the elderly patients: 60-69), which may indicate a subclinical vestibular hydrops. This could be accounted for by an autoimmune process in the inner ear, quite possible in SLE.
TL;DR: Conformational investigation of the ANGII type I antagonists in DMSO by 1D-NOE spectroscopy revealed that the Tyr-Ile-His bend, a conformational property found in ANGII and [Sar1]ANGII is not present, providing for the first time an important conformational difference between angiotensin II agonists andtype I antagonists.
Abstract: Type I angiotensin II antagonists with O-methyl-L-homoserine [HSer(gamma-OMe)] and delta-methoxy-L-norvaline [Nva(delta-OMe)] at position 8 have been prepared by the solid-phase method, purified by reverse-phase HPLC, and bioassayed in the rat uterus, and their backbone conformational properties were investigated by nuclear Overhauser effect (NOE) spectroscopy. [Sar1,HSer-(gamma-OMe)8]ANGII, [HSer(gamma-OMe)8]ANGII, [Des1,HSer(gamma-OMe)8]ANGII, [Sar1,Nva(delta-OMe)8]-ANGII, and [Des1,Nva(delta-OMe)8]ANGII had, respectively, the following antagonist activities, pA2: 7.6, 7.5, < 6.0, 7.1, and 6.9. Analogs of [Sar1]ANGII with delta-hydroxy-L-norvaline [Nva(delta-OH)], delta-methoxy-L-norvaline [Nva(delta-OMe)], 4'-carboxyphenylalanine [Phe(4'-COOH)], and 4'-(trifluoromethyl)phenylalanine [Phe(4'-CF3)] at position 4 were also prepared by solid phase and bioassayed in the rat uterus. [Sar1,Nva(delta-OH)4]ANGII, [Aib1,Nva(delta-OMe)4]ANGII, [Sar1,DL-Phe(4'-COOH)4]ANGII, and [Sar1,DL-Phe(4'-CF3)4]ANGII had, respectively, agonist activities as follows: 4%, 1.5%, 3%, < 0.1%, and < 0.1%. These data emphasize that replacement of Ile8 in Sarilesin with the higher homologs HSer(gamma-OMe) and Nva(delta-OMe) does not greatly alter the structural requirements necessary for expression of type I antagonist activity, while replacement of the tyrosine hydroxyl in [Sar1]ANGII by the carboxylate or the trifluoromethyl group abolishes activity, suggesting that the tyrosinate pharmacophore cannot be replaced by any negatively charged or electronegative group. Conformational investigation of the ANGII type I antagonists [HSer(gamma-OMe)8]ANGII and [Sar1Nva(delta-OMe)8]ANGII in DMSO by 1D-NOE spectroscopy revealed that the Tyr-Ile-His bend, a conformational property found in ANGII and [Sar1]ANGII (J. Biol. Chem. 1994, 269, 5303) is not present in type I antagonists, providing for the first time an important conformational difference between angiotensin II agonists and type I antagonists.
TL;DR: In this article, the authors present an efficient numerical method for locating and computing to any desired accuracy periodic orbits (stable, unstable, and complex) of any period based on the topological degree of the mapping and is particularly useful for studying the behavior of many dynamical systems of physical interest.
TL;DR: The performance of the presented Stochastic Estimator Learning Automaton (SELA) is superior to all previous well-known S- model ergodic schemes and it is proved that SELA is ϵ-optimal in every S-model random environment.
TL;DR: A cryptographic scheme for encrypting 2-D gray scale images by using a large family of fractals based on a transposition of the image elements implemented by a generator of 2- D hierarchical scanning patterns, derived from a parailel algorithm implementing the creation of the family of scanning patterns.
Abstract: We present a cryptographic scheme for encrypting 2-D gray scale images by using a large family of fractals. This scheme is based on a transposition of the image elements implemented by a generator of 2-D hierarchical scanning patterns producing a large
subset of the (n2)! possible orders defined on a 2-0 image of n x n elements. Each pattern defines a distinct order of pixels and can be
described by an expression, which is considered as the key of the transposition. This transposition cipher can easily be combined with various substitution ciphers, producing efficient product ciphers operating on pictorial data. Two such ciphers are constructed and their effects on real gray value images are shown. Encryption and decryption algorithms are derived from a parailel algorithm implementing the creation of the family of scanning patterns.
TL;DR: The findings suggest that the dermatan sulfate chain can be defined as a copolymer that contains short chondroitin sulfate and long dermatan sulphate regions which are distributed periodically and nonrandomly.
TL;DR: The coexistence state obtained in the periodically operated chemostat is usually periodic, but cases of quasi-periodic and chaotic behavior are also observed.
Abstract: Coexistence of three microbial populations engaged in pure and simple competition is not possible in a chemostat with time-invariant operating conditions under any circumstances. It is shown that by periodic variation of the chemostat dilution rate it is possible to obtain a stable coexistence state of all three populations in the chemostat. This is accomplished by performing a numerical bifurcation analysis of a mathematical model of the system and by determining its dynamic behavior with respect to its operating parameters. The coexistence state obtained in the periodically operated chemostat is usually periodic, but cases of quasi-periodic and chaotic behavior are also observed.
TL;DR: In this article, the catalytic activity of IrO2 catalyst films for the gas phase combustion of ethylene can be increased by up to a factor of 10 via anodic polarization of the IrO 2 catalyst relative to a Au electrode both deposited on Y2O3-stabilized ZrO2 solid electrolyte.
Abstract: The catalytic activity of IrO2 catalyst films for the gas phase combustion of ethylene can be increased by up to a factor of 10 via anodic polarization of the IrO2 catalyst relative to a Au electrode both deposited on Y2O3-stabilized ZrO2 solid electrolyte. The steady-state increase in the catalytic reaction rate is typically 200 higher than the expected rate increase of ethylene combustion calculated from Faraday's law. This is the first demonstration of the effect of non-faradaic electrochemical modification of catalytic activity (NEMCA) using a metal oxide catalyst.
TL;DR: In this article, the influence of vanadium loading and molybdenum presence on the catalytic performance of vanadia-titania (anatase) catalysts for the selective oxidation of toluene was investigated.
Abstract: The influence of vanadium loading and molybdenum presence on the catalytic performance of vanadia-titania (anatase) catalysts for the selective oxidation of toluene was investigated. Two series of V2O5/TiO2 and V2O5-MoO3/TiO2 catalysts were prepared. In the first series the loading of vanadium varied from 0 to 8 mole %, whereas in the second the atomic ratio V/(V + Mo) varied from 0 to 1 while the total loading of active elements (V + Mo) was kept constant and equal to 8 mole %. The samples were characterized by XPS, TPR, XRD and BET measurements. It was found that the activity for the oxidation of toluene and the selectivity for side chain partial oxidation products (benzaldehyde and benzoic acid) exhibited by V2O5/TiO2 catalysts increased with the vanadium loading up to monolayer coverage. This increase was attributed to the parallel increase of the surface concentration of easily reducible isolated vanadium species interacting with the anatase surface. When the vanadium content increased above monolayer coverage both activity and selectivity decreased. V2O5-MoO3/TiO2 catalysts were found to be less active and selective than the corresponding V2O5/TiO2 ones. Molybdenum species supported on anatase were less active for this reaction than vanadium and, in addition, the presence of molybdenum inhibited the interaction between vanadium and anatase leading to a poor vanadium dispersion.
Journal Article•
TL;DR: Conservative surgery achieves satisfactory results in the treatment of hepatic hydatidosis with one patient died, 4 developed complications, and there were 3 recurrences.
Abstract: But : Etudier la mobidite, la mortalite et les recidives apres traitement des kystes hydatiques du foie par une technique conservatrice modifiee. Type d'etude : Prospective ouverte. Provenance : Hopital universitaire, Grece. Patients : Soixante sept patients consecutifs operes de kystes hydatiques du foie entre 1985 et 1990. Methodes : Apres mobilisation du foie et isolement du reste de la cavite peritoneale par des champs inbibes de serum sale a 15%, les kystes ont ete vides de leur contenu, largement ouverts, sterilises par du serum sale a 15%, et ensuite ourles avec un fil tresse resorbable. Des drains ont ete mis en place et un tiers des patients a eu egalement une epiplooplastie (n = 22). Principaux criteres de jugement : La morbidite, la mortalite et le pourcentage de recidives. Resultats : Un patient est decede, 4 ont eu des complications (6%) et il y a eu 3 recidives (4%). Aucune difference n'a ete notee entre les patients qui ont eu une epiplooplastie et ceux qui n'en ont pas eu. Conclusion : La chirurgie conservatrice donne de bons resultats dans le traitement des kystes hydatiques du foie.
15 Jun 1995
TL;DR: In this article, the acidity of industrial titania has been investigated using potentiometric titration and microelectrophoretic mobility measurements, and it was shown that the surface of rutile is more acidic than anatase.
Abstract: The rutile, anatase, and industrial titania (used in catalysis as support and consisting of rutile and anatase)-water solution interfaces were studied using potentiometric titration and microelectrophoretic mobility measurements. Concerning the simple oxides it was found that specific adsorption of the ions of the background electrolyte (NH4NO3) does not take place. The electrical double layer developed in the anatase/aqueous solution and rutile/aqueous solution interfaces is described by the diffuse layer model. On the basis of this model the surface acidity constants, the point of zero charge, and the concentration of the various surface hydroxyls in the pH range 4-8 were calculated using a computer program called SURFEQL. It was confirmed that the surface of rutile is more acidic than the surface of anatase. Concerning industrial titania used in catalysis as support it was demonstrated that its surface has a patchwise structure consisting of rutile (10%) and anatase (90%) regions. The acid-base behavior of this material is identical to a mechanical mixture of rutile and anatase of the same composition. Taking into account its patchwise structure we calculated the variation, with pH, of the concentration of each surface hydroxyl of industrial titania [TirOH+2, TiIOH, TirO-, TiaOH+2, TiaOH, and TiaO-; a, r stand for anatase and rutile, respectively]. These variations allow one to model the deposition of species containing catalytically active ions on the surface of industrial titania.
TL;DR: In this article, the creeping flow through a swarm of spheroidal particles, that move with constant uniform velocity in the axial direction through an otherwise quiescent Newtonian fluid, is analyzed with a sphroid-in-cell model.
TL;DR: By applying well-known results on the positive invariance of polyhedral sets, an eigenstructure assignment approach to this problem is established and this approach enables one to derive a linear state-feedback stabilizing control law which makes the set of states where the control constraints are respected positively invariant.
TL;DR: The applicability of cooperating knowledge-based system (CKBS) techniques in environmental decision support is discussed, with special emphasis on a typical example, the Distributed Chemical Emergencies Manager (DCHEM).
Abstract: The paper discusses the applicability of cooperating knowledge-based system (CKBS) techniques in environmental decision support. The reasons for using CKBSs are given first. Existing environmental CKBSs are discussed, with special emphasis on a typical example, the Distributed Chemical Emergencies Manager (DCHEM). The methodological framework applied to the building of DCHEM, the knowledge acquisition technique used, and the architecture of the developed system are also described.
TL;DR: In this article, the dynamic behaviour of a system of three-dimensional, massless, rigid, surface foundations of arbitrary shape perfectly bonded to the elastic half-space is numerically studied with the frequency domain boundary element method.
Abstract: The dynamic behaviour of a system of three-dimensional, massless, rigid, surface foundations of arbitrary shape perfectly bonded to the elastic half-space is numerically studied with the frequency domain boundary element method. This method employs the dynamic Green's function for the surface of the half-space and this results in a discretization of only the soil-foundation interfaces. In addition, use of isoparametric quadratic quadrilateral boundary elements increases the accuracy of the method, which is confirmed by comparison with other known numerical solutions. Externally applied loads, harmonically varying with time, are considered. The through the soil coupling effect between the foundations as a function of distance and frequency is assessed through extensive parametric studies involving two and four rigid foundations being isolated or interconnected. It is found that the assertion of ATC-3 regulations that omission of coupling effects leads to conservative results is not always correct for all frequencies.