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Search Results: 1 - 10 of 11300 matches for " Tsiamis George "
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Detection and characterization of Wolbachia infections in laboratory and natural populations of different species of tsetse flies (genus Glossina)
Doudoumis Vangelis,Tsiamis George,Wamwiri Florence,Brelsfoard Corey
BMC Microbiology , 2012, DOI: 10.1186/1471-2180-12-s1-s3
Abstract: Background Wolbachia is a genus of endosymbiotic α-Proteobacteria infecting a wide range of arthropods and filarial nematodes. Wolbachia is able to induce reproductive abnormalities such as cytoplasmic incompatibility (CI), thelytokous parthenogenesis, feminization and male killing, thus affecting biology, ecology and evolution of its hosts. The bacterial group has prompted research regarding its potential for the control of agricultural and medical disease vectors, including Glossina spp., which transmits African trypanosomes, the causative agents of sleeping sickness in humans and nagana in animals. Results In the present study, we employed a Wolbachia specific 16S rRNA PCR assay to investigate the presence of Wolbachia in six different laboratory stocks as well as in natural populations of nine different Glossina species originating from 10 African countries. Wolbachia was prevalent in Glossina morsitans morsitans, G. morsitans centralis and G. austeni populations. It was also detected in G. brevipalpis, and, for the first time, in G. pallidipes and G. palpalis gambiensis. On the other hand, Wolbachia was not found in G. p. palpalis, G. fuscipes fuscipes and G. tachinoides. Wolbachia infections of different laboratory and natural populations of Glossina species were characterized using 16S rRNA, the wsp (Wolbachia Surface Protein) gene and MLST (Multi Locus Sequence Typing) gene markers. This analysis led to the detection of horizontal gene transfer events, in which Wobachia genes were inserted into the tsetse flies fly nuclear genome. Conclusions Wolbachia infections were detected in both laboratory and natural populations of several different Glossina species. The characterization of these Wolbachia strains promises to lead to a deeper insight in tsetse flies-Wolbachia interactions, which is essential for the development and use of Wolbachia-based biological control methods.
Detection and Characterization of Wolbachia Infections in Natural Populations of Aphids: Is the Hidden Diversity Fully Unraveled?
Antonis A. Augustinos, Diego Santos-Garcia, Eva Dionyssopoulou, Marta Moreira, Aristeidis Papapanagiotou, Marios Scarvelakis, Vangelis Doudoumis, Silvia Ramos, Antonio F. Aguiar, Paulo A. V. Borges, Manhaz Khadem, Amparo Latorre, George Tsiamis, Kostas Bourtzis
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0028695
Abstract: Aphids are a serious threat to agriculture, despite being a rather small group of insects. The about 4,000 species worldwide engage in highly interesting and complex relationships with their microbial fauna. One of the key symbionts in arthropods is Wolbachia, an α-Proteobacterium implicated in many important biological processes and believed to be a potential tool for biological control. Aphids were thought not to harbour Wolbachia; however, current data suggest that its presence in aphids has been missed, probably due to the low titre of the infection and/or to the high divergence of the Wolbachia strains of aphids. The goal of the present study is to map the Wolbachia infection status of natural aphids populations, along with the characterization of the detected Wolbachia strains. Out of 425 samples from Spain, Portugal, Greece, Israel and Iran, 37 were found to be infected. Our results, based mainly on 16S rRNA gene sequencing, indicate the presence of two new Wolbachia supergroups prevailing in aphids, along with some strains belonging either to supergroup B or to supergroup A.
Presence of Extensive Wolbachia Symbiont Insertions Discovered in the Genome of Its Host Glossina morsitans morsitans
Corey Brelsfoard equal contributor,George Tsiamis equal contributor,Marco Falchetto,Ludvik M. Gomulski,Erich Telleria,Uzma Alam,Vangelis Doudoumis,Francesca Scolari,Joshua B. Benoit,Martin Swain,Peter Takac,Anna R. Malacrida,Kostas Bourtzis ,Serap Aksoy
PLOS Neglected Tropical Diseases , 2014, DOI: 10.1371/journal.pntd.0002728
Abstract: Tsetse flies (Glossina spp.) are the cyclical vectors of Trypanosoma spp., which are unicellular parasites responsible for multiple diseases, including nagana in livestock and sleeping sickness in humans in Africa. Glossina species, including Glossina morsitans morsitans (Gmm), for which the Whole Genome Sequence (WGS) is now available, have established symbiotic associations with three endosymbionts: Wigglesworthia glossinidia, Sodalis glossinidius and Wolbachia pipientis (Wolbachia). The presence of Wolbachia in both natural and laboratory populations of Glossina species, including the presence of horizontal gene transfer (HGT) events in a laboratory colony of Gmm, has already been shown. We herein report on the draft genome sequence of the cytoplasmic Wolbachia endosymbiont (cytWol) associated with Gmm. By in silico and molecular and cytogenetic analysis, we discovered and validated the presence of multiple insertions of Wolbachia (chrWol) in the host Gmm genome. We identified at least two large insertions of chrWol, 527,507 and 484,123 bp in size, from Gmm WGS data. Southern hybridizations confirmed the presence of Wolbachia insertions in Gmm genome, and FISH revealed multiple insertions located on the two sex chromosomes (X and Y), as well as on the supernumerary B-chromosomes. We compare the chrWol insertions to the cytWol draft genome in an attempt to clarify the evolutionary history of the HGT events. We discuss our findings in light of the evolution of Wolbachia infections in the tsetse fly and their potential impacts on the control of tsetse populations and trypanosomiasis.
Theories and cures of the rheumatic diseases during the byzantine period (330-1453 a.D.)
C. Tsiamis,N.T. Economou,E. Poulakou-Rebelakou
Reumatismo , 2011, DOI: 10.4081/reumatismo.2006.157
Abstract: Most Byzantine medical texts described the rheumatic diseases. The Byzantine physicians, based on the ancient Greek texts, explained the causes of rheumatic diseases, described their symptoms and proposed certain treatments. The Byzantine medical sources described various types of rheumatic diseases, as inflammatory arthritis, chronic deformans polyarthritis, and gout. As it can be concluded by the available medical sources, during the Byzantine period rheumatic diseases constituted a serious medical and social problem, reprenting a remarkable cause of disability, and this complaint was part of the epidemiological interest of the Byzantine physicians.
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.
Comparative Value of Simple Inflammatory Markers in the Prediction of Left Ventricular Systolic Dysfunction in Postacute Coronary Syndrome Patients
Panagiotis Aggelopoulos,Christina Chrysohoou,Christos Pitsavos,Lambros Papadimitriou,Catherine Liontou,Demosthenes Panagiotakos,Eleftherios Tsiamis,Christodoulos Stefanadis
Mediators of Inflammation , 2009, DOI: 10.1155/2009/826297
Abstract: Objectives. We sought to assess the comparative value of inflammatory markers on the occurrence of left ventricular systolic dysfunction (LVSD) after an acute coronary syndrome (ACS). Methods. During 2006–2008, 760 patients with an ACS were enrolled. C-reactive protein (CRP) and white blood cell (WBC) count were measured during the first 12 hours of hospital admission. Results. CRP levels and WBC count were significantly higher in those who developed LVSD compared to those who did not. The analysis revealed that a 10 mg/dL increase of CRP levels and a 1000/L increase in WBC are associated with a 6% and a 7% increase in the likelihood of developing LVSD, respectively. Furthermore, WBC count at entry and CRP have almost the same predictive value for development of LVSD after an ACS (2=0.109 versus 2=0.093). Conclusions. Serum CRP levels and WBC count at entry are almost equally powerful independent predictors of LVSD, after an ACS.
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.
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