Showing papers by "University of Crete published in 1990"
TL;DR: A new laser refractive procedure is being developed in a rabbit model that might induce stable corneal changes because of the preservation of the anterior layers of the cornea.
Abstract: A new laser refractive procedure is being developed in a rabbit model. With a modified microkeratome, central corneal flaps were created. An ArF excimer laser was used to produce 3-mm-diameter circular ablations on the central part of the exposed stromal bed. One group of animals was sacrificed immediately postoperatively, and both the dissected and ablated areas were studied using scanning electron microscopy. A second group of animals was sacrificed 4 weeks postoperatively. In this group, the subsequent healing of the corneas was studied using light microscopy. At 3 days, the wounded stromal areas showed some degree of haze. Haze was progressively reduced over 1 month, but it could be still discerned biomicroscopically. A hemicircular opacification corresponding to the flap edges was also apparent on slit-lamp examination. Microscopic observation showed that the epithelium was normal, except at the flap margins, where it was thickened. An increased number of keratocytes was observed in the interface between the flap stroma and the ablated area. The procedure might induce stable corneal changes because of the preservation of the anterior layers of the cornea.
614 citations
TL;DR: The renal parenchymal thickness decreases about 10% per decade of increasing age in both men and women, consistent with previously reported findings based on autopsy material.
Abstract: Renal parenchymal thickness was estimated by using CT in 360 patients with no evidence of renal disease. In each patient, the measurements were normalized to the transverse diameter of the vertebral body and a reference table was formulated. The renal parenchymal thickness decreases about 10% per decade of increasing age in both men and women. These findings are consistent with previously reported findings based on autopsy material. The proposed table may be useful as a criterion for assessing normal renal parenchyma on CT.
119 citations
TL;DR: In this article, the deHoffmann-Teller frame was used to detect the magnetopause normal vector, N, and the average plasma velocity along N is used to deduce a boundary layer thickness of about 1.3 R{sub E}.
Abstract: Convection electric fields, E{sub c} = {minus}V{sub p}{times}B, measured during a magnetopause/boundary layer encounter at low latitude by the AMPTE/IRM spacecraft, are shown to yield an accurate determination of the magnetopause normal vector, N, even though the magnetic shear across the magnetopause was small. The average plasma velocity along N is used to deduce a boundary layer thickness of about 1.3 R{sub E}. Analysis of E{sub c} in the magnetopause itself reveals the existence of a deHoffmann-Teller frame in which the flow is nearly field aligned and approximately Alfvenic, indicating that the magnetopause was a rotational discontinuity; this is interpreted as a signature that magnetic-field reconnection was occurring somewhere on the magnetopause.
81 citations
TL;DR: Photoinhibitory illumination of isolated oxygen evolving photosystem II core complexes results in a substantial degradation of the Dl‐protein, accompanied by the appearance of high amounts of at least 4 different degradation products.
81 citations
TL;DR: Results revealed that NADH-GDH from leaf, shoot, and root tissues are closely related proteins, and addition of ammonium ions to the culture medium of in vitro grown explants resulted in a significant increase in NADH
Abstract: Rabbit antiserum was raised against NADH-glutamate dehydrogenase (GDH) isoenzyme 1, purified from leaves of Vitis vinifera L cv Soultanina and its specificity was tested This antiserum was used for immunocharacterization of the GDH from leaf, shoot, and root tissues The antiserum recognized the seven isoenzymes of NADH-GDH and precipitated all the enzyme activity from the three tissues tested Western blot following SDS-PAGE revealed the same protein band for the three tissues, with a molecular mass of 425 kilodaltons corresponding to NADH-GDH subunit Results, based on the immunological studies, revealed that NADH-GDH from leaf, shoot, and root tissues are closely related proteins Furthermore, addition of ammonium ions to the culture medium of in vitro grown explants resulted in a significant increase in NADH-GDH activity in root, shoot, and leaf tissues
63 citations
TL;DR: In this paper, a simple extension of the Heisenberg model which is abstracted from the large-U limit of the Hubbard Hamiltonian and includes charge fluctuations is studied, and some basic features of the T = 0 phase diagram within a suitable 1/N expansion.
Abstract: We study a simple extension of the Heisenberg model which is abstracted from the large-U limit of the Hubbard Hamiltonian and includes charge fluctuations. An attempt is made to elucidate some basic features of the T = 0 phase diagram within a suitable 1/N expansion. We find that the ferromagnetic boundary dictated by a naive application of the Nagaoka, theorem is actually incorrect because of an instability induced by phase separation. We derive what we believe to be the correct ferromagnetic boundary for sufficiently high dimension, and provide a detailed description of the ensuing phase separation. We also find that a uniform canted antiferromangetic state is stable over a nontrivial region of the phase diagram. Potential implications of these results for the physics of the original Hubbard model are discussed briefly.
61 citations
TL;DR: In this article, the authors compared the infaunal and epifaunal assemblages from surveys encompassing 121 grab stations and 152 Agassiz trawl samples respectively, collected between 1980 and 1985.
49 citations
TL;DR: The use of two-dimensional NMR techniques and spin simulation afforded a detailed set of chemical shift and spin-spin coupling data for the main tautomeric forms of D-fructose in dimethyl sulfoxide and aqueous solutions.
Abstract: The use of two-dimensional NMR techniques and spin simulation afforded a detailed set of chemical shift and spin–spin coupling data for the main tautomeric forms of D-fructose in dimethyl sulfoxide and aqueous solutions. Differences in vicinal coupling parameters for β-D-fructofuranose in the two solvents are taken as evidence that this tautomer incorporates intramolecular hydrogen bonding in dimethyl sulfoxide, which helps to account for its exceptional prominence in this solvent. The enhanced proportion of α-D-fructofuranose in dimethyl sulfoxide over that in water also receives comment. Also described are corresponding data from NMR measurements on the tautomeric equilibria of disaccharides that contain a D-fructose reducing-end residue, and of the homomorphic ketose, L-galacto-2-heptulose, i.e. structurally related compounds that may entail different kinds of hydrogen-bonding possibilities. Evidence indicating the presence of extensive inter-residue hydrogen bonding within the individual tautomers of the disaccharide turanose is provided by the pattern of hydroxyl proton chemical shifts in dimethyl sulfoxide.
47 citations
TL;DR: The analysis by capillary GC and GC-MS of the volatile oil of Calamintha nepeta (L.) Savi subsp. glandulosa (Req.) P.W. Ball, endemic to Greece, showed the presence of at least 46 components, of which 31 were identified, corresponding to 98% of the total as mentioned in this paper.
Abstract: The analysis by capillary GC and GC–MS of the volatile oil of Calamintha nepeta (L.) Savi subsp. glandulosa (Req.) P.W. Ball, endemic to Greece, showed the presence of at least 46 components, of which 31 were identified, corresponding to 98% of the total. The major components were found to be the two diastereoisomers of piperitone oxide (55%) and β-bisabolene (8.5%).
35 citations
TL;DR: Two cases of atypical syphilis in HIV‐infected patients assuming characteristics of malignant syphilis are described with special emphasis on the peculiarities of histologic and immunohistochemical findings.
Abstract: Two cases of atypical syphilis in HIV-infected patients assuming characteristics of malignant syphilis are described with special emphasis on the peculiarities of histologic and immunohistochemical findings.
33 citations
TL;DR: In this paper, three chorion cDNA clones from a Ceratitis capitata ovarian library were isolated by differential screening of the library using as probes 32P-labeled poly(A)+ mRNAs obtained from hand-staged medfly choriogenic versus prechoriogenic follicles.
TL;DR: The finding ofIL-2-R on non-lymphoid cells may disclose new functions for IL-2, and this work has recently demonstrated its presence on leukemic cells from various hemopoietic lineages.
TL;DR: 5-azacytidine, when given to pregnant females before the ectoplacental cone formation, dramatically increases fetal loss, which correlates with class II antigen expression in the labyrinthine trophoblast zone, suggesting that the maintenance of the class II antigens-negative expression on the placenta is indeed necessary to avoid maternal immune attack and ensure fetal survival.
TL;DR: Axenic shoot cultures of virus-free Vitis vinifera L. cv.
Abstract: Axenic shoot cultures of virus-free Vitis vinifera L. cv. Soultanina were a highly efficient source for isolation of viable protoplasts. Optimum results were obtained with leaves of 50–100 mg fresh weight, leaf discs of 0.7 cm in diameter, 100 and 15 U ml-1 Cellulase R-10 and Macerozyme R-10, respectively, and 18 h reaction time in either light or in darkness. Protoplast yield was approx. 25×106 viable protoplasts per g fresh weight and their size ranged from 12 to 44 μm. During a 20-day culture period, the maximum survival rate obtained was approx. 40%. A plating density of 10×105 protoplasts per ml resulted in increased survival rates. Various growth regulators and glutamine did not significantly improve survival rates of protoplasts, whereas extract from coconut added to the culture medium caused an increase in the survival rates of protoplasts. Cell elongation at a significant rate and divisions were observed. [14C]glucose uptake was studied as an index of cell membrane integrity and functioning. Uptake rate of glucose by protoplasts was linear for up to 60 min, fully inhibited by NaN3, with an optimum pH of 4.8. Protoplasts 24 h old exhibited significantly lower rates of glucose uptake.
TL;DR: In this paper, a mixed method of close coupling and discretization techniques is used for initial Gaussian wave packets localized at particular regions of phase space of HCN which is treated as a system with three vibrational degrees of freedom.
TL;DR: In this paper, the authors studied properties of single operators not of rank one and conditions on the algebra which will ensure that all its single operators are of rank 1, and showed that for many algebras of operators, S is single if and only if S has rank 1 operators.
TL;DR: A case of large Brunner’s gland adenoma is reported with special emphasis on its radiological appearances, which has been paid little attention in the radiologic literature concerning such tumors.
TL;DR: The ene reaction of N-Phenyl-1,2,4-triazoline-3,5-dione with alkenes shows a remarkable preference for hydrogen abstraction from the group which is geminal to the larger substituent of the double bond as mentioned in this paper.
TL;DR: It is demonstrated that the proper place of the Tomimatsu-Sato solutions is in the description of cylindrically symmetric spacetimes, as opposed to stationary axisymmetricSpacetime, which describes a beam-like-shaped pulse of gravitational radiation scattered by a cosmic string.
Abstract: We demonstrate that the proper place of the Tomimatsu-Sato solutions is in the description of cylindrically symmetric spacetimes, as opposed to stationary axisymmetric spacetimes. More particularly, we consider a version of the \ensuremath{\delta}\ifmmode \tilde{}\else \~{}\fi{}=2 Tomimatsu-Sato solutions, obtained from the standard Tomimatsu-Sato solutions by an analytic continuation, that describe a cylindrically symmetric spacetime. It admits a regular axis, is asymptotically flat, and is smooth everywhere but the axis where it exhibits a conical, but not a curvature, singularity. The spacetime describes a beam-like-shaped pulse of gravitational radiation scattered by a cosmic string.
TL;DR: Using the non-ionic detergent dodecyl-β-D-maltoside, the photosynthetic membrane was exposed only to one mild detergent and that resulted in more stable preparations and even under these mild conditions the D1-D2-Cyt b559 did not retain the primary quinone QA.
Abstract: Using the non-ionic detergent dodecyl-β-D-maltoside we have developed a preparative method for the isolation of the 43 kDa, 47 kDa and D1-D2-Cyt b
559 species directly from thylakoid membranes. In contrast to previous procedures the photosynthetic membrane was exposed only to one mild detergent and that resulted in more stable preparations. The isolated species were examined spectroscopically and it was found that even under these mild conditions the D1-D2-Cyt b
559 did not retain the primary quinone QA.
TL;DR: In this article, it was shown that the q-deformed quantum oscillator, with q=exp(2πi/k), k being an integer, and the quantum mechanical system consisting of a charge moving on a k-point discretized circle, around a shielded magnetic flux Φ= 1 2 π(k+2), have identical spectra.
TL;DR: In this article, the authors tried to answer three basic questions: (1) To what extent does the institution of computer-resource teachers (CRTs) constitute an effective strategy for the implementation of computers in schools, and (2) to what extent have CRTs fulfilled their assigned role in Stockholm schools? (3) What are the factors which either inhibit and/or facilitate the integration of computers into schools?
Abstract: We cannot expect any substantial success for the integration of computers in schools and across subjects unless questions of planning, design, development and training are placed in the context of a school setting. The author attempts to answer three basic questions: (1) To what extent does the institution of computer-resource teachers (CRTs) constitute an effective strategy for the implementation of computers in schools? (2) To what extent have CRTs fulfilled their assigned role in Stockholm schools? (3) What are the factors which either inhibit and/or facilitate the integration of computers in schools? The results show that, although the integration of computers across school subjects was moderate, due to various constraints, the role of CRTs in the implementation process was crucial. Additionally, school-based in-service computer training seems to be more effective than other forms of training. The contribution of CRTs to this form of training is very important in addressing the urgent need for training and to ensure the successful integration of computers into schools across all subjects. A partnership approach should be adopted between the CRT and the teacher(s) who want to learn about computers, and CRTs should be allowed adequate time to carry out this role.
TL;DR: In most areas binding of L-[3H]glutamate was increased when incubation was done in chloride-containing medium, but this increase was statistically significant in only few of these areas.
TL;DR: The Preconditions for the Exercise of an Effective Technological Development Policy as discussed by the authors is a case study of software houses in Greece, and the case study is presented in detail in Section 2.1.
TL;DR: In this article, the structural features for the exhibition of mesomorphism by homopolymers and copolymers of N-alkyl polymaleamic acid, monoesters of polymaleic acid, or mixed amide-ester derivatives were determined.
Abstract: Polymaleic anhydride prepared by γ-rays irradiation of maleic anhydride was used as a reactive polymer and reacted with certain long-chain aliphatic amines and/or alcohols as well as with the mesogenic biphenylamine. The homopolymers and copolymers that were prepared, i.e., derivatives of N-alkyl polymaleamic acid, monoesters of polymaleic acid, or mixed amide-ester derivatives, were primarily investigated as far as their property to show thermotropic liquid crystalline character is concerned. By this investigation the structural features for the exhibition of mesomorphism by these polymers were determined.
TL;DR: A method for the calculation of multiphoton ionization, including above-threshold ionization and autoionization, which goes beyond the one-electron approximation is presented.
Abstract: We present a method for the calculation of multiphoton ionization, including above-threshold ionization and autoionization, which goes beyond the one-electron approximation. We illustrate the method with examples of calculations in He and Mg.
TL;DR: In this paper, the authors compare both the public and private costs of technical-vocational and of academic upper secondary education in Greece and find that the private costs are much higher for academic than for vocational education while the public costs are similar.
Journal Article•
TL;DR: It is suggested that in neutropenic patients monocyte/macrophages exhibit most likely a qualitative defect in CSA production, which may account at least in part for the impaired granulopoiesis observed in drug-induced neutropenia.
Abstract: Colony stimulating activity (CSA) and granulocyte-macrophage progenitor cells (GM-CFC) were assayed in the bone marrow and peripheral blood of 17 patients with drug-induced chronic neutropenia. Leukocyte-derived and monocyte/macrophage-derived CSA from the neutropenic patients was found to be significantly decreased compared to normal control. However, bone marrow and peripheral blood GM-CFC were within normal limits. These data suggest that in neutropenic patients monocyte/macrophages exhibit most likely a qualitative defect in CSA production, which may account at least in part, for the impaired granulopoiesis observed in drug-induced neutropenia.
TL;DR: In this article, structural features that induce, modify or even inhibit the exhibition of liquid crystallinity in a series of aliphatic α-ω diquaternary and α-ϵ diphosphate amphiphiles were investigated.
Abstract: In this study we investigate the structural features that induce, modify or even inhibit the exhibition of liquid crystallinity in a series of aliphatic α-ω diquaternary and α-ω diphosphate amphiphiles. It was found that the appearance of thermally stable liquid crystalline phases is favored by increasing chain length and employing triethylammonium and phosphate groups as heads of the amphiphiles. On the contrary, the bulky diallylethylammonium group has a rather destructive effect on the existence of the mesophase.