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Search Results: 1 - 10 of 11342 matches for " George Xanthopoulos "
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Active Modified Atmosphere Packaging of Fresh-cut Bell Peppers: Effect on Quality Indices
Helen Manolopoulou,Gregory Lambrinos,George Xanthopoulos
Journal of Food Research (JFR) , 2012, DOI: 10.5539/jfr.v1n3p148
Abstract: Fresh-cut green bell peppers (Capsicum annuum L.) were stored in modified atmosphere packaging (MAP) made of impermeable high-density polyethylene film. Two in-packaging atmospheres and storage temperatures (0 oC and 5 oC) were tested. The respiration rate of the unpackaged produce and the in-package gas concentration, mass loss, firmness, skin colour, ascorbic acid and visual quality of the packaged produce were estimated. Cutting, increased respiration rate of the unpackaged produce by 24% compared to the intact produce for the same storage temperature. After 5 days of storage at 5 °C, significant O2 depletion of the active modified atmosphere was found. Limited mass loss (0.4-0.5% of the initial mass) and firmness degradation were estimated in both storage temperatures due to the beneficial effect of packaging. The hue angle (h*) reduction was limited in all cases and the initial green colour was preserved. Initial ascorbic acid content was preserved at 0 °C, but significantly increased at 5 °C. The visual quality of the packaged produce was assessed by six trained panelists and found that was not significantly changed at 0 °C storage. In conclusion, the tested active MAP maintained the initial quality indices of fresh-cut peppers (cv. Twingo F1) for up to 10 days at 0 °C but not at 5 °C.
A Comparison of Spectral Angle Mapper and Artificial Neural Network Classifiers Combined with Landsat TM Imagery Analysis for Obtaining Burnt Area Mapping
George P. Petropoulos,Krishna Prasad Vadrevu,Gavriil Xanthopoulos,George Karantounias,Marko Scholze
Sensors , 2010, DOI: 10.3390/s100301967
Abstract: Satellite remote sensing, with its unique synoptic coverage capabilities, can provide accurate and immediately valuable information on fire analysis and post-fire assessment, including estimation of burnt areas. In this study the potential for burnt area mapping of the combined use of Artificial Neural Network (ANN) and Spectral Angle Mapper (SAM) classifiers with Landsat TM satellite imagery was evaluated in a Mediterranean setting. As a case study one of the most catastrophic forest fires, which occurred near the capital of Greece during the summer of 2007, was used. The accuracy of the two algorithms in delineating the burnt area from the Landsat TM imagery, acquired shortly after the fire suppression, was determined by the classification accuracy results of the produced thematic maps. In addition, the derived burnt area estimates from the two classifiers were compared with independent estimates available for the study region, obtained from the analysis of higher spatial resolution satellite data. In terms of the overall classification accuracy, ANN outperformed (overall accuracy 90.29%, Kappa coefficient 0.878) the SAM classifier (overall accuracy 83.82%, Kappa coefficient 0.795). Total burnt area estimates from the two classifiers were found also to be in close agreement with the other available estimates for the study region, with a mean absolute percentage difference of ~1% for ANN and ~6.5% for SAM. The study demonstrates the potential of the examined here algorithms in detecting burnt areas in a typical Mediterranean setting.
Signature of a universal statistical description for drift-wave plasma turbulence
Johan Anderson,Pavlos Xanthopoulos
Physics , 2010, DOI: 10.1063/1.3505824
Abstract: This Letter provides a theoretical interpretation of numerically generated probability density functions (PDFs) of intermittent plasma transport events. Specifically, nonlinear gyrokinetic simulations of ion-temperature-gradient turbulence produce time series of heat flux which exhibit manifestly non-Gaussian PDFs with enhanced tails. It is demonstrated that, after the removal of autocorrelations, the numerical PDFs can be matched with predictions from a fluid theoretical setup, based on the instanton method. This result points to a universality in the modeling of intermittent stochastic process, offering predictive capability.
Ion temperature gradient turbulence in helical and axisymmetric RFP plasmas
I. Predebon,P. Xanthopoulos
Physics , 2015, DOI: 10.1063/1.4921645
Abstract: Turbulence induced by the ion temperature gradient (ITG) is investigated in the helical and axisymmetric plasma states of a reversed field pinch device by means of gyrokinetic calculations. The two magnetic configurations are systematically compared, both linearly and nonlinearly, in order to evaluate the impact of the geometry on the instability and its ensuing transport, as well as on the production of zonal flows. Despite its enhanced confinement, the high-current helical state demonstrates a lower ITG stability threshold compared to the axisymmetric state, and ITG turbulence is expected to become an important contributor to the total heat transport.
Asymptotic behavior of solutions for a semibounded nonmonotone evolution equation
Nikos Karachalios,Nikos Stavrakakis,Pavlos Xanthopoulos
Abstract and Applied Analysis , 2003, DOI: 10.1155/s1085337503210022
Abstract: We consider a nonlinear parabolic equation involving nonmonotonediffusion. Existence and uniqueness of solutions are obtained, employing methods for semibounded evolution equations. Also shown is the existence of a global attractor for the corresponding dynamical system.
Preventing Another Crisis: Quality Data for MBS Markets
Andrew Kumiega,Ben Van Vliet,Apostolos Xanthopoulos
Accounting and Finance Research , 2012, DOI: 10.5430/afr.v1n1p162
Abstract: Mortgage-backed securities and derivatives pricing and risk models often assume static input distributions. As real-world uncertainty increases, the need for real-time data updates becomes imperative. Quality standards for pool level data would ensure the orderly re-pricing of risk. Many industries abide by government mandated quality data standards. We argue that what the financial industry needs is what the NIST already provides to manufacturing and the NASS provides to agriculture. The financial industry has evolved and now needs continuous monitoring framework for the securitization process to control the complex mathematical models and technological systems that enable disintermediation in the mortgage markets.
IRAM observations of JVAS/CLASS gravitational lenses
E. Xanthopoulos,F. Combes,T. Wiklind
Physics , 2000, DOI: 10.1046/j.1365-8711.2001.04414.x
Abstract: We have searched for molecular absorption lines at millimeter wavelengths in eleven gravitational lens systems discovered in the JVAS/CLASS surveys of flat spectrum radio sources. Spectra of only one source 1030+074 were obtained in the 3-, 2- and 1.3-millimeter band at the frequencies corresponding to common molecular transitions of CO and HCO+ as continuum emission was not found in any of the other sources. We calculated upper limits to the column density in molecular absorption for 1030+074, using an excitation temperature of 15 K, to be N_{CO} < 6.3 x 10^{13} cm^{-2} and N_{HCO+} < 1.3 x 10^{11} cm^{-2}, equivalent to hydrogen column density of the order N_H < 10^{18} cm^{-2}, assuming standard molecular abundances. We also present the best upper limits of the continuum at the lower frequency for the other 10 gravitational lenses.
MERLIN imaging of the maser flare in Markarian 348
E. Xanthopoulos,A. M. S. Richards
Physics , 2000, DOI: 10.1046/j.1365-8711.2001.04817.x
Abstract: MERLIN images of Mrk 348 at 22 GHz show water maser emission at 0.02 - 0.11 Jy, within approximately 0.8 pc of the nucleus. This is the first direct confirmation that molecular material exists close to the Seyfert 2 nucleus. Mrk 348 was observed in 2000 May one month after Falcke et al. (2000) first identified the maser in single-dish spectra. The peak maser flux density has increased about threefold. The masing region is < 0.6 pc in radius. The flux density of radio continuum emission from the core has been rising for about 2 years. The maser-core separation is barely resolved but at the 3 sigma significance level they are not coincident along the line of sight. The masers lie in the direction of the northern radio lobes and probably emanate from material shocked by a jet with velocity close to c. The correlation between the radio continuum increase and maser flare is explained as arising from high level nuclear activity through a common excitation mechanism although direct maser amplification of the core by masers tracing a Keplerian disc is not completely ruled out.
Venture Capital and Innovation in Europe  [PDF]
George Geronikolaou, George Papachristou
Modern Economy (ME) , 2012, DOI: 10.4236/me.2012.34058
Abstract: In this paper we search for evidence signifying whether VC activity is demand or supply stimulated. Namely, we examine whether innovation and entrepreneurship are fostered by Venture Capital (VC) investments or whether innovative entrepreneurship is a precondition of a VC involvement. Based on a European panel of VC investments, we test the direction of causality between VC and innovation (proxied by annual patent applications at the European Patents Office). We present evidence indicating that causality runs from patents to VC suggesting that, in Europe, innovation seems to create a demand for VC and not VC a supply of innovation. In this sense, innovative ideas seem to lack more than funds in Europe. We explain our findings on the basis of information asymmetry issues and irreversibility considerations of VC investments.
Response of Mouse Breast Cancer Cells to Anastrozole, Tamoxifen, and the Combination
J. M. Xanthopoulos,A. E. Romano,S. K. Majumdar
Journal of Biomedicine and Biotechnology , 2005, DOI: 10.1155/jbb.2005.10
Abstract: The murine breast cancer cells (4T1) grown both in female BALB/c mice and in culture were treated with anastrozole (50 μg/mL), tamoxifen citrate (5 μg/mL), and the combination of the two drugs in order to determine treatment efficacies, toxic potential, and the mechanism of cell death. The in vivo treatments were evaluated by monitoring tumor growth, development, and life span. The in vitro effects were measured through cell growth kinetics, cell proliferation, mitochondrial membrane potential disruption assay, and light and scanning electron microscopy. All drug treatments extended the mean life span of the 4T1-inoculated tumor-bearing mice; however, only tamoxifen and combination treatments statistically increased the life span when compared to untreated mice. Although the most drug inhibitory effect on cell multiplication was observed in the combination treatment, both anastrozole and tamoxifen individually inhibited cell proliferation significantly at most time periods in this mouse breast cancer cell line. The mitochondrial membrane potential disruption assay demonstrated significant increase in the percent of cells undergoing apoptosis in all treatment groups. However, the combination treatment was the most effective in inducing cell death via apoptosis. Light and scanning electron microscopy of the treated cells revealed characteristics such as rounding, clumping, and shrinkage of the cells as well as formation of cell surface blebbing and apoptotic bodies suggestive of cell death via apoptotic pathway.
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