Showing papers by "University of Crete published in 1992"
24 Aug 1992
TL;DR: These constraints require that for every clock i, the constraint ~ x i] = 0 or ~ xi] > c i holds at innnitely many regions along the path (here, c i is the largest constant in a constraint involving x in the enabling conditions of G) and can be used to handle progressiveness in the reduced region graphs.
Abstract: 15 For a formula = 93 c , the algorithm is the same; the initial partition now distinguishes between the cases ~ x0] = 0 and 0 < ~ x0] c and 0 < ~ x0] 6 6 c. The analysis for = 83 c is similar; the initial partition now needs to account for the progressiveness assumption also (as in the case of 83). Automatic veriication of nite-state concurrent systems using temporal-logic speciications. 14 certain sets of regions. In particular, these constraints require that for every clock i, the constraint ~ xi] = 0 or ~ xi] > c i holds at innnitely many regions along the path (here, c i is the largest constant in a constraint involving x in the enabling conditions of G). We can use this fact to handle progressiveness in our reduced region graphs.
175 citations
TL;DR: In this paper, the authors proposed an incentive scheme appropriate for a dynamic framework, which takes the form of charges per unit deviation between desired and observed pollutant accumulation paths, and these paths converge to the socially desirable ambient pollutant concentration.
173 citations
TL;DR: It is concluded that hypothyroidism affects respiratory muscle strength and that this weakness is linearly related to thyroid hormone levels.
91 citations
TL;DR: The data suggest that cytoskeletal alterations in response to cell swelling may be involved in the regulation of hepatic metabolism by cell volume and that cell swelling exerts rapid and marked effects on the state of actin polymerization and increases actin mRNA levels.
80 citations
73 citations
TL;DR: It is concluded that Police-Schools Liaison has only limited positive effects, as predicted from critiques of the traditional 'contact hypothesis'.
Abstract: This paper evaluates the impact of Police-Schools Liaison on young people's views and attitudes about the police and offending. It reports the first, large-scale, independent evaluation of this social intervention. The evaluation (based on 1245 secondary-school pupils) compares views of the police in schools with (target) and without (control) a full-time Schools Liaison Officer (SLO). Although attitudes to the police are marginally positive, they become less so over one year. There is no evidence that Schools Liaison input into the target schools slows or halts this decline, or that it affects perceptions of the seriousness of offences, and the likelihood of identification associated with crime. This weak impact is, at least in part, attributable to the low reported rates of direct contact, and the judged atypicality of the SLO. Target-school pupils judged their SLO positively, but as distinct from the 'police in general'. Their view of the SLO had a direct impact on their liking of the police in general, but there was no effect for contact. We conclude that Police-Schools Liaison has only limited positive effects, as predicted from critiques of the traditional 'contact hypothesis'.
57 citations
TL;DR: Preliminary normative BUA results indicate that BUA may be a useful technique for detection of persons at risk.
Abstract: Broadband ultrasound attenuation (BUA) on the os calcis has been proposed as a safe and reliable technique for evaluating skeleted status. The present study provides preliminary normative BUA results on 93 female subjects divided into five age groups. These data can be used as a guide for comparing the results of individual studies. The diagnosis of osteoporosis was determined from lateral calcaneus and spine radiographs. Postmenopausal osteoporotic female subjects had significantly lower BUA values than normal women (P <0.001). There was a significant negative linear relationship between BUA and age in the postmenopausal subjects. No correlation was found between body size pararneters (weight, height, and body mass index) and ultrasound attenuation. These results indicate that BUA may be a useful technique for detection of persons at risk.
56 citations
TL;DR: In this article, the authors studied linearized gravitons on the D-dimensional open submanifold spanned by de Sitter conformal coordinates and showed that the resulting polatization tensors have vanishing zero components and are transverse and traceless, just as in flat space.
55 citations
TL;DR: In this article, the Mandelstam covariant is introduced as an interpolating field constructed from geodesics, parallel transport, and the Riemann tensor, which is nonlocal in all gauges and therefore may not give the usual S -matrix beyond tree order.
54 citations
Journal Article•
TL;DR: The availability of the new granulocyte colony stimulating factors which can shorten the duration of neutropenia could represent a significant improvement in the management of fungal infections in cancer patients.
Abstract: Major advances in anticancer treatment have contributed to an increased frequency of severe fungal infections in patients with neoplastic diseases. Neutropenia remains the most important among the predisposing factors related to the malignancy or its treatment. Most fungal infections are caused by the commonly recognized opportunistic fungi Candida spp and Aspergillus spp, and the pathogenic fungi Cryptococcus neoformans, Histoplasma capsulatum, Coccidiodes immitis, and less often by Blastomyces dermatidis. However, recently newer pathogens such as Pheohyphomycetes, Hyalohyphomycetes, Zygomycetes and other fungi of emerging importance such as Torulopsis glabrata, Trichosporon beigelii, Malassezia spp, Saccharomyces spp, Hansenula spp, Rhodotorula spp, and Geotrichum candidum have appeared as significant causes of infection in this patient population. The increasing frequency of fungal infections is of great concern because of the difficulties in diagnosis and treatment. Amphotericin B remains the mainstay of antifungal treatment despite its toxicity and limited efficacy. Liposomal Amphotericin B may be more effective and less toxic. The activity of the azoles in immunocompromised patients is low. New azoles such as fluconazole and itraconazole may show future promise. The availability of the new granulocyte colony stimulating factors which can shorten the duration of neutropenia could represent a significant improvement in the management of fungal infections in cancer patients. As a preventive measure, the invasive procedures that predispose to infections should be done only when absolutely necessary and frequent handwashing by hospital personnel remains an effective prophylactic procedure.
53 citations
TL;DR: In this paper, a Crank-Nicolson-type finite difference scheme for the Kuramoto-Sivashinsky equation in one space dimension with periodic boundary conditions is presented.
Abstract: We analyze a Crank-Nicolson-type finite difference scheme for the Kuramoto-Sivashinsky equation in one space dimension with periodic boundary conditions. We discuss linearizations of the scheme and derive second-order error estimates.
TL;DR: In this paper, the authors used GC/MS and GC/FID analysis on aerosol samples collected seasonally in a coastal area on the north of the island of Crete.
TL;DR: In this paper, the effects of environmental policy, in the form of emission charges or emission limits, on the firm's optimal choices of productive and abatement inputs are analyzed.
TL;DR: Several approaches for classifying two-dimensional objects which are based on the use of both invariant boundary transformations and artificial neural networks were implemented and compared and the strengths and weakness of each approach were shown.
TL;DR: To investigate the cellular localization of the 90-kilodalton heat shock protein (HSP90) and its interaction with the cytoskeleton, single- and double-staining immunofluorescence microscopy of cytoskeletal proteins and HSP90 in the absence and presence of cytOSkeletal inhibitors is performed.
Abstract: To investigate the cellular localization of the 90-kilodalton heat shock protein (HSP90) and its interaction with the cytoskeleton, we performed single- and double-staining immunofluorescence microscopy of cytoskeletal proteins and HSP90 in the absence and presence of cytoskeletal inhibitors. As a model, we used a human endometrial adenocarcinoma cell line (Ishikawa cells), which expresses HSP90. We confirmed the recently reported colocalization of HSP90 with microtubules. However, Ishikawa cells treated with 10(-5) M of the antimicrotubule agents colchicine or triethyl lead showed residual filamentous structures stained with anti-HSP90 antibodies, while no microtubules were visualized with anti-tubulin antibodies. In the presence of 10(-5) M cytochalasin B, the microfilament staining of the cells disappeared, while residual filamentous structures were labeled with anti-HSP90 antibodies. Furthermore, Ishikawa cells treated with 10(-5) M triethyl lead and stained with anti-HSP90 antibodies demonstrated residual filamentous structures, clearly different from those of reorganized vimentin intermediate filaments. Conversely, similar reorganized morphology of filamentous structures stained with both anti-HSP90 and anti-cytokeratins antibodies were observed when Ishikawa cells were treated with 2 x 10(-5) M cytochalasin B and 2 x 10(-5) M colchicine. HSP90 was also present in Ishikawa cell preparations of the Triton X-100 insoluble cytoskeleton. In addition, Triton-insoluble cytoskeleton treated with 10(-5). M triethyl lead and double stained with anti-HSP90 and anti-vimentin antibodies demonstrated clearly different filamentous patterns, when exposed on the same photographic plaque.(ABSTRACT TRUNCATED AT 250 WORDS)
TL;DR: The results indicate that the increase in NADH-GDH specific activity was due to de-novo synthesis of the α-subunit of GDH and the assembly of only the more anodic isoenzymes.
Abstract: When callus derived from shoot segments of Vitis vinifera L. was transferred to ammonium-containing medium the aminating activity of NAD(H)-glutamate dehydrogenase (GDH, EC 1.4.1.2) increased significantly. This increase in enzyme activity closely paralleled an increase in the protein of the GDH α-subunit (43.0 kDa), as detected by sodium dodecyl sulfate (SDS) gel electrophoresis and Western-blotting. A similar correlation was observed between the deaminating activity and the β-subunit (42.5 kDa) which both decreased during this treatment. Using [35S]methionine and immunochemical detection it was shown that the rate of synthesis of the α-subunit increased considerably in the ammonium-containing medium while there was no detectable synthesis of the β-subunit. At the isoenzyme level, ammonium caused an increase in the de-novo synthesis and hence the activity staining of the more anodic isoenzymes, which are hexameric and consist mainly of α-subunits. The results indicate that the increase in NADH-GDH specific activity was due to de-novo synthesis of the α-subunit of GDH and the assembly of only the more anodic isoenzymes.
TL;DR: During a 5 year period, leiomyomas of the small intestine are identified in six patients using enteroclysis with excellent correlation between the radiological appearances and morphology of the pathology specimens.
16 Dec 1992
TL;DR: It is shown that if a sufficiently large number of high-order connections between neurons is allowed, the RHONN model is capable of approximating the input-output behavior of general dynamical systems to any degree of accuracy.
Abstract: The authors study the stability and convergence properties of recurrent high-order neural networks (RHONNs) as models of nonlinear dynamical systems. The overall structure of the RHONN consists of dynamical elements distributed throughout the network in the form of dynamical neurons, which are interconnected by high-order connections. It is shown that if a sufficiently large number of high-order connections between neurons is allowed, the RHONN model is capable of approximating the input-output behavior of general dynamical systems to any degree of accuracy. Based on the linear-in-the-weights property of the RHONN model, the authors have developed identification schemes and derived weight adaptive laws for adjustment of the weights. The convergence and stability properties of these weight adaptive laws have been analyzed. In the case of no modeling error, the state error between the system and the RHONN model converges to zero asymptotically. If modeling errors are present, the sigma -modification is proposed as a method of guaranteeing the stability of the overall scheme. The feasibility of applying these techniques has been demonstrated by considering the identification of a simple rigid robotic system. >
TL;DR: It is demonstrated that the release of IR-beta END from Ishikawa cells in culture is inhibited by estradiol and dexamethasone, suggesting that endometrial beta END is under estrogen and glucocorticoid regulation, as is the case with hypothalamic and pituitary POMC-derived peptides.
Abstract: Immunoreactive beta-endorphin (IR-beta END) is present in human endometrium. Several indirect lines of evidence suggest that endometrial beta END is under steroid hormone control, i.e. IR-beta END is detectable in the secretory, but not the proliferative, endometrium, and progesterone administration increases the concentration of IR-beta END in uterine secretions of ovariectomized gilts. To study the effect of steroid hormones on endometrial beta END, we first questioned whether Ishikawa human endometrial adenocarcinoma cells (which respond to steroid hormones) express the proopiomelanocortin (POMC) gene. Indeed, on Northern blot analysis, a RNA similar or identical in size to pituitary POMC mRNA was present in Ishikawa cell RNA extracts. IR-beta END was also present in Ishikawa cell extracts and culture medium, which coeluted with synthetic human beta END in a Sephadex G-50 column. Ishikawa cells released most of their IR-beta END into the culture medium. Estradiol decreased the release of IR-beta END fr...
TL;DR: A low-temperature EPR study, with both diamagnetic and paramagnetic lanthanide ions, has demonstrated a close interaction between the lanthanides and the tyrosine radical YD, taken as evidence that the extrinsic 17 and 23 kDa do not bind Lanthanide/calcium ions.
TL;DR: The results confirm that in thyrotoxicosis respiratory muscle weakness occurs that affects both inspiratory and expiratory muscles and statistically significant linear relationship was found between PImax and PEmax.
Abstract: We undertook this study to investigate respiratory muscle strength in relation to thyroid function in 20 thyrotoxic patients and in a group of 20 normal subjects matched for age and sex. Global respiratory muscle strength was assessed by measuring mouth pressure during maximal static inspiratory (PImax) and expiratory (PEmax) efforts. We also measured VC, FVC, and FEV1 as well as thyroid-related hormones (T3, T4, TSH). Measurements were made once in normal subjects and twice in thyrotoxic patients, before and 3 months after medical treatment. Our results showed that both maximal pressures were significantly reduced (p less than 0.0001) before treatment in thyrotoxic patients in relation to the mean values of the normal subjects (p less than 0.0001), and they increased significantly (p less than 0.0003) after treatment. Lung volumes were significantly reduced (p less than 0.0001) before and increased significantly (p less than 0.008) after treatment. The ratio FEV1/FVC did not change. A statistically significant linear relationship was found when PImax of patients with thyrotoxicosis before treatment and of normal subjects were plotted against thyroid hormones (T3, T4) (r = -0.746 and r = -0.745, respectively, p less than 0.001). Similarly, a statistically significant linear relationship was found between PEmax and T3 and T4 (r = -0.837 and r = -0.838, respectively, p less than 0.001). No relationship was found between maximal pressures and TSH. Finally, a significant linear relationship was found between PImax and PEmax (r = 0.872, p less than 0.001). Our results confirm that in thyrotoxicosis respiratory muscle weakness occurs that affects both inspiratory and expiratory muscles.(ABSTRACT TRUNCATED AT 250 WORDS)
TL;DR: Fluorescent lipid peroxidation products were determined in nodal and internodal stem explants from micropropagated Vitis vinifera L. cv.
TL;DR: It appears that after cholinergic stimulation, PC12 dynorphin is cosecreted with catecholamines, a phenomenon described for a number of neuropeptides, including the proenkephalin-derived opioids.
Abstract: The PC12 is a cloned rat pheochromocytoma cell line that retains a number of chromaffin cell characteristics, such as the presence of nicotinic cholinergic receptors, the synthesis and secretion of catecholamines, and the expression of a number of neuropeptide genes. The PC12 cell line is a useful model for the study of neuronal development, since PC12 cells can be induced to differentiate toward sympathetic neurons after exposure to nerve growth factor (NGF). PC12 cells can also be induced to differentiate toward the opposite direction, i.e. toward mature chromaffin cells. Morphological and biochemical changes mark the differentiation of PC12 cells toward either direction. Among the substances proposed as biochemical markers of PC12 cell differentiation toward chromaffin cells is the endogenous opioid precursor proenkephalin and its posttranslational peptide products. Indeed, the proenkephalin gene is expressed in both adrenal chromaffin and PC12 cells. The secretion of enkephalins from PC12 cells increa...
TL;DR: The potential for four-alpha-helix bundle folding is reflected primarily in the pattern of residue occurrence in the heptad and not in the overall amino acid composition of the protein.
Abstract: The sequences of four-alpha-helical bundle proteins are characterized by a pattern of hydrophilic and hydrophobic amino acids which is repeated every seven residues. At each position of the heptad repeat there are specific constraints on the amino acid properties which result from the topology of the tertiary motif. These constraints give rise to patterns of amino acid distribution which are distinct from those of other proteins. The distributions in each of the heptad positions have been determined by a statistical analysis of structural and sequence data derived from seven families of aligned protein sequences. The constitution of each position is dominated by a very small number of different amino acids, with the core positions consisting overwhelmingly of Leu and Ala. The positional preferences of the individual amino acids can be generally interpreted in terms of residue properties and topological constraints. The potential for four-alpha-helix bundle folding is reflected primarily in the pattern of residue occurrence in the heptad and not in the overall amino acid composition of the protein. Possible applications of this analysis in structure predictions, sequence alignments and in the rational design and engineering of four-alpha-helical bundle proteins are discussed.
TL;DR: In this paper, the authors construct and analyze finite element methods for approximating the equations of linear elastodynamics, using mixed elements for the discretization of the spatial variables.
Abstract: We construct and analyze finite element methods for approximating the equations of linear elastodynamics, using mixed elements for the discretization of the spatial variables. We consider two different mixed formulations for the problem and analyze semidiscrete and up to fourth-order in time fully discrete approximations.L 2 optimal-order error estimates are proved for the approximations of displacement and stress.
TL;DR: In this paper, the authors consider a convex body in Euclidean space R d, d ≥ 2, with volume V ( K ) = 1, and n ≥ d + 1, where n is a natural number.
Abstract: Let K be a convex body in Euclidean space R d , d ≥2, with volume V ( K ) = 1, and n ≥ d +1 be a natural number. We select n independent random points y 1 , y 2 , …, y n from K (we assume they all have the uniform distribution in K ). Their convex hull co { y 1 , y 2 , …, y n } is a random polytope in K with at most n vertices. Consider the expected value of the volume of this polytope It is easy to see that if U : R d → R d is a volume preserving affine transformation, then for every convex body K with V ( K ) = 1, m ( K, n ) = m ( U ( K ), n ).
TL;DR: A novel model is proposed for the processing of multimeric replicative viroid RNA intermediates through RNA cleavage and ligation catalyzed by a host endoribonuclease to indicate that circularization is driven by RNA structure and not governed by a particular sequence.
TL;DR: The authors found that most of the differences between the two countries are best explained by the country and the student gender variables, and that the culture and the society one lives in appears to be of greater importance in determining one's attitudes towards computers more than does, for example, the possession of a computer.
Abstract: With the introduction and use of computers in schools, the study of gender differences in attitude towards computers becomes of particular interest. This article concerns the interaction of gender, culture and attitude in computers among Japanese and Swedish ninth‐grade school students. One of the major findings of this study is that most of the differences between the two countries are best explained by the country and the student gender variables. Accordingly, the culture and the society one lives in appears to be of greater importance in determining one's attitudes towards computers more than does, for example, the possession of a computer. The overall country effects are influenced more by the females in both countries than by males. [1] The data this study is based upon were collected while the author was an assistant professor at the Institute of International Education, University of Stockholm and a Japan Foundation Fellow, affiliated with the National Institute of Educational Research of ...
TL;DR: A prospective study on murine typhus was carried out in Chalkis General Hospital in 1985, during which 49 cases, serologicaly confirmed using indirect fluorescence assay, were diagnosed.
Abstract: Cases of murine typhus were described in Chalkis, capital town of the island Evia in Greece. In the present work a prospective study on murine typhus was carried out in Chalkis General Hospital in 1985, is presented. During this year 49 cases, serologicaly confirmed using indirect fluorescence assay, were diagnosed. Signs and symptoms of the patients as well as preliminary epidemiological data are reported in this paper.