Showing papers by "University of Patras published in 1991"
TL;DR: In this paper, the authors present experimental results obtained in an accelerated carbonation apparatus using a variety of techniques, including TGA, and extend the mathematical model developed recently to include the entire range of ambient relative humidities.
260 citations
TL;DR: It is demonstrated that discrepancies between total and exogenous glucose oxidation in relation to the peak occurrence time, as well as the absolute quantities, could be adequately explained by the interference of the bicarbonate stores.
Abstract: In 13C02 breath tests, based on 13C:12C ratio measurements, the appearance of 13C in exhaled C02 was monitored after the administration of a 13C-la-belled compound. Independently of the substrate used, the existence of a bicarbonate pool into which the C02 produced enters before being exhaled, imposes a delay on the appearance of changes in the 13C:12C ratio. To estimate the nature and magnitude of this delay, we applied a two-compartment model to describe the kinetics of the body bicarbonate pool and we evaluated the 13C:12C ratio of C02 entering that pool from the measured 13C:12C ratio in the exhaled C02 after an oral intake of “naturally labelled” 13C-glucose. Our results demonstrated that discrepancies between total and exogenous glucose oxidation in relation to the peak occurrence time, as well as the absolute quantities, could be adequately explained by the interference of the bicarbonate stores.
105 citations
94 citations
TL;DR: It is found that the time TPN is started is important in influencing the course of the disease and in the development of local complications, as well as in the mortality rate.
Abstract: The influence of total parenteral nutrition (TPN) was studied in 67 patients with severe acute pancreatitis having three or more criteria according to Ranson (mean +/- SD = 3.8 +/- 0.21). Although TPN has been reported to not be of benefit in the progress and severity of the disease, we have found that the time TPN is started is important in influencing the course of the disease and in the development of local complications, as well as in the mortality rate. Patients whose TPN was started within the first 72 hours of the disease had a 23.6% complication rate and 13% mortality, in comparison with patients whose TPN was started later in the course of the disease, who had a 95.6% complication rate (p less than 0.01) and a mortality rate of 38% (p less than 0.03). The nutritional status of the patients during TPN administration of 28.4 days was maintained either steady or was improved, as assessed by nitrogen balance, serum levels of transferrin (p less than 0.05), and albumin (p less than 0.05). The administration of fat solution, either to prevent essential fatty acid deficiency or to provide part of the caloric requirements, was found to cause neither clinical nor laboratory worsening of the disease. All pancreatic fistulae that developed during the course of the disease spontaneously closed in patients receiving TPN without operation in a mean period of 33.3 days, and all pseudocysts subsided in an average of 18.3 days. Those who died (overall mortality rate 24%) had had uncontrollable sepsis, which resulted in hypercatabolism and multiple system organ failure.(ABSTRACT TRUNCATED AT 250 WORDS)
90 citations
TL;DR: The immunocytochemical approach showed that the entire rat cerebellum is innervated by DA fibers, and an antiserum against dopamine (DA), and specific [3H]ligands in order to shed more light on the dopaminergic system of the rat Cerebellum support the existence of a DA system.
89 citations
TL;DR: In this paper, the catalytic activity of polycrystalline Pt films deposited on β-Al 2 O 3, a Na + -conducting solid electrolyte, can be altered dramatically and reversibly by polarizing the catalyst-solid electrolyte interface.
87 citations
TL;DR: Deletion of genes encoding shikimate pathway enzymes represents a possible approach to generation of rationally attenuated strains of M. tuberculosis for use as live vaccines, and indicates a common ancestral origin for genes encoding the catabolic dehydroquinases of fungi and the biosynthetic dehydoquinases present in some prokaryotes.
Abstract: The Mycobacterium tuberculosis shikimate pathway genes designated aroB and aroQ encoding 3-dehydroquinate synthase and 3-dehydroquinase, respectively were isolated by molecular cloning and their nucleotide sequences determined. The deduced dehydroquinate synthase amino acid sequence from M. tuberculosis showed high similarity to those of equivalent enzymes from prokaryotes and filamentous fungi. Surprisingly, the deduced M. tuberculosis 3-dehydroquinase amino acid sequence showed no similarity to other characterised prokaryotic biosynthetic 3-dehydroquinases (bDHQases). A high degree of similarity was observed, however, to the fungal catabolic 3-dehydroquinases (cDHQases) which are active in the quinic acid utilisation pathway and are isozymes of the fungal bDHQases. This finding indicates a common ancestral origin for genes encoding the catabolic dehydroquinases of fungi and the biosynthetic dehydroquinases present in some prokaryotes. Deletion of genes encoding shikimate pathway enzymes represents a possible approach to generation of rationally attenuated strains of M. tuberculosis for use as live vaccines.
85 citations
15 Oct 1991
TL;DR: In this paper, the effects of pore-size correlations on mercury intrusion/retraction curves are investigated with a new theoretical simulator, focusing on the class of porous materials that can be represented as networks of chambers and throats.
Abstract: The effects of pore-size correlations on mercury intrusion/retraction curves are investigated with a new theoretical simulator. Attention is focused on the class of porous materials that can be represented as networks of chambers and throats. Simulations are made with three types of networks: uncorrelated, c-t correlated, and c-c & c-t correlated. It is found that, whereas the effects of c-t correlation on mercury porosimetry curves are relatively weak, the effects of c-c & c-t correlation are strong. The c-c & c-t correlation widens the intrusion curve, extending it in ranges of both low and high pressure. The residual mercury saturation is somewhat smaller for c-c & c-t correlated networks than for uncorrelated ones, but part of this difference is caused by boundary effects. Type c-c & c-t correlated networks can be used to represent porous media with nonrandom heterogeneities at the microscopic level.
81 citations
TL;DR: In this article, the feasibility of using all-pole and all-zero model approximations of room transfer functions was examined especially in respect to the degree that such approximation models are suitable for removing room reverberation from signals.
79 citations
TL;DR: It is shown that the property of approximation is preserved when the maxmin compositional rule of inference is applied to approximately equal values of fuzzy variables and fuzzy relations.
75 citations
TL;DR: In this paper, the results of a statistical analysis on landslide phenomena in Greece are presented based upon 800 case-histories of landslide incidents, recorded up to 1986, retrieved from an original number of more than 1500 coded engineering reports and studies.
Abstract: The results of a statistical analysis on landslide phenomena in Greece are presented here. The task is based upon 800 case-histories of landslide incidents, recorded up to 1986, retrieved from an original number of more than 1500 coded engineering reports and studies. The object concerns village areas and the road network. It especially refers to their frequency distribution and their consequences on different geological formations, altitudes, rain-fall, slope angles etc. Furthermore, assessments for the above parameters were made and certain interrelations were studied. Additionally an engineering geological map of Greece as well as landslide distribution and frequency zone maps were compiled on the basis of the evaluated data.
TL;DR: Proline is not compatible with enzymes extracted from Salsola soda, a glycine-betaine former adapted to saline soils, and a co-evolution of enzyme structure and osmolyte systems, at least at the species level, is inferred from results.
TL;DR: Leaflet strips, fixed under dynamic loading between zero and a predefined maximum load, set at an early post-transition state, give parameters not significantly different from those of human valves.
TL;DR: In this article, a Kelvin probe was used to measure in situ the changes induced in the work function of Pt catalyst films deposited on doped ZrO2 and β-Al2O3 solid electrolytes upon electrochemical supply or removal of O2− and Na+ to or from the catalyst surface.
TL;DR: In this paper, the authors applied cyclic linear potential sweep chronoamperometry (CLPWC) to investigate the chemisorptive and catalytic properties of porous metal catalyst films also functioning as electrodes in solid electrolyte cells.
TL;DR: In this paper, the frequency domain boundary element method employing the Green's function of Kausel-Peek-Hull for a thin layered half-space is applied to vibration isolation problems and the effect of the inhomogeneity on the wave screening effectiveness of trenches is studied.
TL;DR: In this article, two submarine hydrothermal fields off Nisiros and Kos islands in the eastern sector of the Hellenic Volcanic Arc have been investigated using analyses of submarine Hydrothermal waters and sediments.
TL;DR: In this paper, the authors present a theoretical model of the process of collision and coalescence of a pair of mobilized ganglia in porous media, and investigate the conditions under which coalescence is prompt or difficult.
01 Jun 1991
TL;DR: Efficient sequential and parallel solutions to the problem of answer on-line queries requesting the shortest distance between any two vertices in G, based on the hammock decomposition of a planar digraph and the use of separators for computing quickly internal distances in the graph.
Abstract: We provide here efficient sequential and parallel solutions to the following problem: given a planar digraph G (with real edge weights but no negative cycles) for preprocessing, answer on-line queries requesting the shortest distance (or path) between any two vertices in G. Our algorithms for preprocessing need O(n log n + q2) space and O(n log n + q2) sequential time. (Here q is the cardinality of a set of faces of a planar embedding of G that cover all vertices.)A parallel implementation on a CREW PRAM needs also O(n log n + q2) space and runs in O(log2n) time using O(n + M(q)) processors (where M(q) is the number of processors required to multiply two q × q matrices in O(log q) time), provided that the q faces are given by the input.This enables us to achieve O(log n) time using a single processor for a “distance” query, or O(L + log n) time for a “path” query (where L is the length of the path). Note that this is a considerable improvement over previous results in the case where q = o(n). Our techniques are based on the hammock decomposition of a planar digraph and the use of separators for computing quickly internal distances in the graph. Several other results are achieved. For outerplanar graphs, our algorithms preprocess the graph in O(n logn) space and run either in O(n log n) sequential time, or in O(log2n) time using O(n) processors on a CREW PRAM. A “distance” query can be answered in O(log n) time using a single processor. A “path” query is answered in O(L + log n) time. An optimal solution is given in the case of trees. We achieve O(1) time per “distance” query andwe need O(n) sequential time, or O(log n) time and O(n/log n) processors (on an EREW PRAM) for preprocessing. A “path” query is answered in O(L) time.
TL;DR: In this article, the hydrogenation of benzene, naphthalene and biphenyl over monometallic and bimetallic catalysts supported on γ-Al2O3 or TiO2 was investigated in a three-phase slurry reactor at a temperature of 300 °C and a hydrogen pressure of 66 atm.
TL;DR: In this article, it was shown that the catalytic activity and selectivity of polycrystalline Pt for the oxidation of methanol to formaldehyde and Co 2 can be dramatically and reversibly affected when oxygen anions O 2− are electrochemically pumped to or from the Pt catalyst surface.
TL;DR: The Xanthi pluton is a series of Oligocene subduction-related granodiorites in northern Greece as mentioned in this paper, which is located on the ENE-trending Kavala-Komotini fault zone.
Abstract: The Xanthi pluton is one of a series of Oligocene subduction-related granodiorites in northern Greece. Its emplacement was controlled by major faults. It is located on the ENE-trending Kavala–Komotini fault zone, which probably originated as a strike-slip fault. Geophysical data show that the pluton is laccolith-shaped, extending many kilometres south of the fault. Andesitic dykes several million years older than the pluton indicate a NE–SW-directed extensional stress field. Mineral lineations plunging to the SW reflect continued extension during cooling of the pluton. Subsequent jointing and dykes of aplite and lamprophyre reflect continued extension. Although this could result from extensional pull-apart at a bend during dextral strike-slip motion on the Kavala–Komotini fault, there is no evidence for subsequent strike-slip deformation. Furthermore, two similar laccolithic plutons are unrelated to the Kavala–Komotini fault and the regional extent of thick Oligocene sediments suggests an extensional environment. During the extension that created a ramp space along the listric fault bounding the Xanthi basin, into which the granite was intruded, the Kavala–Komotini fault acted as a transfer fault. Reactivation of early joints occurred during late Oligocene–Early Miocene compression. Faults within the pluton parallel to the Kavala–Komotini fault accompanied extension during Neogene basin formation. Emplacement of subduction-related magma into ramp space developed along listric faults, to produce laccolith-like plutons, may be a common feature of back-arc extension.
TL;DR: In this article, a 3D trajectory analysis of particle deposition in unit cells of the constricted-tube type is developed, and the particle size and pore geometry effects on the rate of deposition are thoroughly studied and shown to be important for various cell orientations.
Abstract: A 3-D trajectory analysis of particle deposition in unit cells of the constricted-tube type is developed. Creeping newtonian How of the suspension through the unit cells is assumed, and the flow field in each unit cell is computed using the collocation solution provided by Tilton and Payatakes (1984). Particle trajectory equations are developed for the three-dimensional case, taking into account the hydrodynamic forces and torques, gravity, the London-van der Waals force, and the double ionic layer force. The one-step trajectory approach is used to predict the rate and pattern of deposition in a unit cell of arbitrary orientation. Numerical results agree with the experimental observation that deposition in oblique flow channels contributes substantially to the overall rate of deposition. Particle size and pore geometry effects on the rate of deposition are thoroughly studied and shown to be important for various cell orientations. This method can be used in a 3-D network analysis to estimate the overall f...
01 Apr 1991
TL;DR: In this article, the effect of fluid topology, pore size, and pore body to pore throat aspect ratio during quasi-static imbibition for the air-mercury system is demonstrated in terms of experimentally obtained capillary pressure curves.
Abstract: Mercury porosimetry was studied in glass-etched micromodels with the aid of an experimental apparatus that enables the accurate measurement of capillary pressures and mercury saturations, as well as the observation of microdisplacement mechanisms at the pore level. The effect of fluid topology, pore size, and pore body to pore throat aspect ratio during quasi-static imbibition for the air—mercury system is demonstrated in terms of experimentally obtained capillary pressure curves. Imbibition is shown to be determined by the interplay of bond-withdrawal (snap-off in throats) and site-withdrawal (withdrawal from pores) processes. Under conditions of small variability in pore body and pre throat size and for relatively small pore body to pore throat aspect ratio, imbibition phenomena are controlled by the fluid topology in a deterministic manner. That is, withdrawal occurs first from pore throats by the snap-off mechanism and proceeds in pore bodies in a manner that preserves the continuity of the nonwetting phase (nwp). Critical capillary pressures were measured for the withdrawal of mercury from pores and throats under various configurations of capillary interfaces. Theoretical calculations were in qualitative agreement with experimental values. For fully saturated capillary networks, snap-off events in pore throats initiate the withdrawal of mercury. The conjecture that the frontal advance mechanism dominates mercury withdrawal over cluster growth at high initial mercury saturation is not valid for conditions whereby all faces of the pore network are exposed to a mercury sink.
TL;DR: In this paper, an almost inverse linear relation between heat flow and Curie depths was found, which was used to construct the Curie isotherms from the existing heat flow data.
Abstract: The objective of this study is to understand the nature and extent of the regional geothermal system at depth beneath the area of Greece by constructing the Curie isotherms. Spectral analysis of aeromagnetic data in conjunction with heat flow information revealed an almost inverse linear relation between heat flow and Curie depths and was used to construct the Curie isotherms from the existing heat flow data. The results showed that Curie depths in the area range from about 20 km in western Greece, up to 1 km beneath the Hellenic volcanic arc. These results are consistent with the existing geothermal and geotectonic regime in the area.
TL;DR: In this article, the synthesis and properties of a key intermediate for arsonolipids, rac-1,2-dihydroxypropyl-3-arsonic acid and its salts, are described.
Abstract: The synthesis and properties of a key intermediate for arsonolipids, rac-1,2-dihydroxypropyl-3-arsonic acid and its salts, are described. The mechanism of the Meyer reaction with β-hydroxy alkyl halides is discussed.
TL;DR: A computer algorithm based on a method for dealing with the so-called ‘inverse problem’ is presented and produces the solution semi-lattice formed by the fuzzy subsets A ⊂ U satisfying the fuzzy relational equation A⊂ R = B.
TL;DR: The nature of the breast lesion was the most common cause of inadequate sampling, followed by the experience of the aspirator, which could be attributed to sampling errors, the criteria of adequacy, and interpretation.
Abstract: Fine-needle aspiration (FNA) is a valuable technique to use in the evaluation of breast lesions; however, inadequate and discrepant diagnoses do occur. To identify the source and nature of inaccuracies related to the method we studied 39 cases in which FNA posed diagnostic problems. These problems could be attributed to sampling errors (71.8%), to the criteria of adequacy we use at our institution (2.5.6%), and to interpretation (2.6%). The nature of the breast lesion (68%) was the most common cause of inadequate sampling, followed by the experience of the aspirator (32%).
TL;DR: In this article, a new class of lipids, arsonolipids or rac-1,2-diacyloxypropyl-3-arsonic acids, have been synthesized by acylating tetrabutyl ammonium hydrogen with myristic, palmitic and stearic anhydrides in the presence of pyridine.
Abstract: A new class of lipids, arsonolipids or rac-1,2-diacyloxypropyl-3-arsonic acids, have been synthesized by acylating tetrabutyl ammonium hydrogen rac-1,2-dihydroxypropyl-3-arsonate with myristic, palmitic and stearic anhydrides in the presence of pyridine. The yields are moderate to low due to decomposition of rac-1,2-dihydroxypropyl-3-arsonic acid and its salts by acylating agents. Acid salts of arsonolipids were prepared by neutralization but neutral salts could not be made.