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Search Results: 1 - 10 of 11281 matches for " George Geroulakos "
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A 75-Year-Old Woman with a Hemispheric Stroke
Stavros K Kakkos,George Geroulakos
PLOS Medicine , 2005, DOI: 10.1371/journal.pmed.0020079
A 75-Year-Old Woman with a Hemispheric Stroke
Kakkos Stavros K,Geroulakos George
PLOS Medicine , 2005, DOI: 10.1371/journal.pmed.0020079.20050521
Effect of zooming on texture features of ultrasonic images
Stavros K Kakkos, Andrew N Nicolaides, Efthyvoulos Kyriacou, Constantinos S Pattichis, George Geroulakos
Cardiovascular Ultrasound , 2006, DOI: 10.1186/1476-7120-4-8
Abstract: Eighteen still B-mode images of carotid plaques were zoomed during carotid scanning (zoom factor 1.3) and both images were transferred to a PC and normalised. Using bilinear and bicubic interpolation, the original images were interpolated in a process of simulating off-line zoom using the same interpolation factor. With the aid of the colour-coded image, carotid plaques of the original, zoomed and two resampled images for each case were outlined and histogram, first order and second order statistics were subsequently calculated.Most second order statistics (21/25, 84%) were significantly (p < 0.05) sensitive to image zooming during scanning, in contrast to histogram and first order statistics (4/25, 16%, p < 0.001, Fisher's exact test). Median (interquartile range) change of those features sensitive to zooming was 18.14% (4.94–28.43). Image interpolation restored these changes, the bicubic interpolation being superior compared to bilinear interpolation (p = 0.036).Texture analysis of ultrasonic plaques should be performed under standardised resolution settings; otherwise a resolution normalisation algorithm should be applied.Cross-sectional studies have shown that echolucent and heterogeneous internal carotid artery plaques on B-mode ultrasound scanning are associated with neurological symptoms [1-3]; similarly prospective studies have confirmed that these subjective plaque characteristics predict future neurological symptoms [4,5]. Our group has investigated objective, computer-assisted methods, which involved standardisation of ultrasonic images (normalisation) and echogenicity measurements [6,7]. We have also, like other groups, investigated objective methods of accessing plaque heterogeneity, known also as texture analysis, and found these helpful in separating symptomatic from asymptomatic plaques [8-12].Image resolution has a significant effect on texture analysis results; this has been shown by studies on remote sensing [13-15], and ultrasound [16]. Images ob
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.
The Index of Invariant Subspaces of Bounded below Operators on Banach Spaces  [PDF]
George Chailos
Advances in Pure Mathematics (APM) , 2012, DOI: 10.4236/apm.2012.22018
Abstract: For an operator on a Banach space , let be the collection of all its invariant subspaces. We consider the index function on and we show, amongst others, that if is a bounded below operator and if , , then If in addition are index 1 invariant subspaces of , with nonzero intersection, we show that . Furthermore, using the index function, we provide an example where for some , holds .
General Markowitz Optimization Problems  [PDF]
George Stoica
Applied Mathematics (AM) , 2012, DOI: 10.4236/am.2012.312A281

We solve two Markowitz optimization problems for the one-step financial model with a finite number of assets. In our results, the classical (inefficient) constraints are replaced by coherent measures of risk that are continuous from below. The methodology of proof requires optimization techniques based on functional analysis methods. We solve explicitly both problems in the important case of Tail Value at Risk.

A Spectral Integral Equation Solution of the Gross-Pitaevskii Equation  [PDF]
George Rawitscher
Applied Mathematics (AM) , 2013, DOI: 10.4236/am.2013.410A3009

The Gross-Pitaevskii equation (GPE), that describes the wave function of a number of coherent Bose particles contained in a trap, contains the cube of the normalized wave function, times a factor proportional to the number of coherent atoms. The square of the wave function, times the above mentioned factor, is defined as the Hartree potential. A method implemented here for the numerical solution of the GPE consists in obtaining the Hartree potential iteratively, starting with the Thomas Fermi approximation to this potential. The energy eigenvalues and the corresponding wave functions for each successive potential are obtained by a spectral method described previously. After approximately 35 iterations a stability of eight significant figures for the energy eigenvalues is obtained. This method has the advantage of being physically intuitive, and could be extended to the calculation of a shell-model potential in nuclear physics, once the Pauli exclusion principle is allowed for.

Rethinking the Formal Methodology (II): Cognitive Content of Relativity (On the Centenary of General Relativity)  [PDF]
George Kirakosyan
International Journal of Astronomy and Astrophysics (IJAA) , 2016, DOI: 10.4236/ijaa.2016.61004
Abstract: An attempt to epistemological completion of formal-math theories of relativity is presented. Causal interpretations of SR and GR are suggested. The problem to physical gist of gravity is explained as a contradiction of cognition vs. intuition. Gravity phenomena are represented as unexplored peculiarity of basic particles. The gravity constant is deduced from the known parameters of the electron.
Small Scale Contractors in Africa’s Emerging Markets: The Case of South Africa  [PDF]
George Hove
Open Journal of Business and Management (OJBM) , 2016, DOI: 10.4236/ojbm.2016.44065
Abstract: In South Africa, the development of Small scale emerging contractors (SSECs) has become vital to bring about economic prosperity and the government has prioritised the advancement of SSECs as the vehicle towards achieving economic growth, development and job creation for previously disadvantaged people. This paper reviewed related construction studies on small scale contractors and highlighted unique roles and challenges as they relate to emerging construction businesses. The paper established that the main challenges affecting SSECs included finance, skills shortage, enabling environment and competition. Based on data analysis, it is imperative for the South African government to develop a clear and more comprehensive small business contracting policies that would enhance growth and profitability of Small scale emerging contractors.
Left Atrial Volume Index in Patients with Dilated Cardiomyopathy—Correlation with Left Ventricular Function  [PDF]
Stanley George
World Journal of Cardiovascular Diseases (WJCD) , 2016, DOI: 10.4236/wjcd.2016.69035
Abstract: Background: The aim of this study was to determine the relation of left atrial (LA) volume and LA volume index with left ventricular function and to determine the association of duration of symptoms and left atrial volume index in patients with dilated cardiomyopathy. Materials and Methods: This was an observational, single centre study conducted in India. A total of 50 patients who were admitted to department of cardiology from July, 2008 to February, 2009 with diagnosis of dilated cardiomyopathy and an ejection fraction of <40% were included. Results: Of the 50 patients, 34 (68%) were males. 27 (54%) patients were in NYHA class II and 23 (46%) patients were in NYHA class III. LA volume was found to be ≥40 ml in all patients. LV function and LA volume were found to be correlated (r = -0.789, p < 0.01). Similarly, there was a correlation between LV function and LA volume index (r = -0.826, p < 0.01). There was no correlation between LA volume index and duration of symptoms (r = 0.04). Conclusion: It can be concluded that there is a strong inverse correlation between LA volume and left ventricular function and also between LA volume index and left ventricular function. The patients with NYHA class III were having larger left atrial volume than those with NYHA class II. Moreover, the duration of symptoms has no correlation with left atrial volume index.
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