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Search Results: 1 - 10 of 831 matches for " Panagiotis Deloukas "
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A Histone Map of Human Chromosome 20q13.12
Pelin Akan, Martin Sahlén, Panagiotis Deloukas
PLOS ONE , 2009, DOI: 10.1371/journal.pone.0004479
Abstract: Background We present a systematic search for regulatory elements in a 3.5 Mb region on human chromosome 20q13.12, a region associated with a number of medical conditions such as type II diabetes and obesity. Methodology/Principal Findings We profiled six histone modifications alongside RNA polymerase II (PolII) and CTCF in two cell lines, HeLa S3 and NTERA-2 clone D1 (NT2/D1), by chromatin immunoprecipitation using an in-house spotted DNA array, constructed with 1.8 kb overlapping plasmid clones. In both cells, more than 90% of transcription start sites (TSSs) of expressed genes showed enrichments with PolII, di-methylated lysine 4 of histone H3 (H3K4me2), tri-methylated lysine 4 of histone H3 (H3K4me3) or acetylated H3 (H3Ac), whereas mono-methylated lysine 4 of histone H3 (H3K4me1) signals did not correlate with expression. No TSSs were enriched with tri-methylated lysine 27 of histone H3 (H3K27me3) in HeLa S3, while eight TSSs (4 expressed) showed enrichments in NT2/D1. We have also located several CTCF binding sites that are potential insulator elements. Conclusions/Significance In summary, we annotated a number of putative regulatory elements in 20q13.12 and went on to verify experimentally a subset of them using dual luciferase reporter assays. Correlating this data to sequence variation can aid identification of disease causing variants.
Data analysis issues for allele-specific expression using Illumina's GoldenGate assay
Matthew E Ritchie, Matthew S Forrest, Antigone S Dimas, Caroline Daelemans, Emmanouil T Dermitzakis, Panagiotis Deloukas, Simon Tavaré
BMC Bioinformatics , 2010, DOI: 10.1186/1471-2105-11-280
Abstract: We analyze data from a mixture experiment where genomic DNA samples from pairs of individuals of known genotypes are pooled to create allelic imbalances at varying levels for the majority of SNPs on the array. We observe that GoldenGate has less sensitivity at detecting subtle allelic imbalances (around 1.3 fold) compared to extreme imbalances, and note the benefit of applying local background correction to the data. Analysis of data from a dye-swap control experiment allowed us to quantify dye-bias, which can be reduced considerably by careful normalization. The need to filter the data before carrying out further downstream analysis to remove non-responding probes, which show either weak, or non-specific signal for each allele, was also demonstrated. Throughout this paper, we find that a linear model analysis of the data from each SNP is a flexible modelling strategy that allows for testing of allelic imbalances in each sample when replicate hybridizations are available.Our analysis shows that local background correction carried out by Illumina's software, together with quantile normalization of the red and green channels within each array, provides optimal performance in terms of false positive rates. In addition, we strongly encourage intensity-based filtering to remove SNPs which only measure non-specific signal. We anticipate that a similar analysis strategy will prove useful when quantifying ASE on Illumina's higher density Infinium BeadChips.Preferential expression of one of the two alleles of a gene has been widely studied in the context of development, where key mechanisms such as genomic imprinting and X-inactivation lead to extreme allelic imbalances [1]. Allele-specific expression has been linked to the susceptibility of many human diseases [2-4].Various experimental techniques exist for measuring ASE [5], including microarray-based approaches that have been used in a number of studies to screen for ASE in a high-throughput manner [6-11]. With microarray
Institutional Inefficiencies in Latin America  [PDF]
Panagiotis Evangelopoulos
Theoretical Economics Letters (TEL) , 2012, DOI: 10.4236/tel.2012.25095
Abstract: In North America the establishment of the institutions of individual liberty and free enterprise demonstrate that prosperity is a function of freedom. Diametrically opposite, Latin America has throughout its history been required to endure attempts at imposing collectivist institutions. The new institutional economic historian approach implies that poor economic performance is attributable to the inefficient institutional framework. Based on this analysis I explain the reasons of the wealth differences between North and Latin America.
Analyzing the Relation between Greek Paper and Paperboard Imports and Exports with Macroeconomic Variables  [PDF]
Panagiotis Koulelis
Open Journal of Forestry (OJF) , 2014, DOI: 10.4236/ojf.2014.45048
Abstract: This paper describes the relation between Greek imports and exports of paper and paperboard and a number of major macroeconomic variables, such as population, gross domestic product, the industrial production index and domestic round wood production. The Pearson correlation coefficient and multiple regression analysis were employed in the analysis of the data. The study shows that there is no significant relation between paper and paperboard imports as a dependent variable and population, gross domestic product and domestic round wood production as independent variables. Despite this, an acceptable model is constructed using only gross domestic product as an independent variable. The study also shows that there is a significant relation between the export of paper and paperboard and gross domestic product, the industrial production index and round wood production. The results indicate that gross domestic product as an independent variable has the greatest effect on wood imports and exports in Greece during the period studied. Using these models is confirmed that the use of socioeconomic variables and the construction of future scenarios for the Greek forest sector is very efficient considering the special characteristics of the Greek economy. These models could help the establishment of economic growth, the reduction of the financial and ecological deficit, the implementation of economic reforms and to increase new investments.
Forest Products Consumption and Trade Deficit in Greece during the Financial Crisis: A Quantitative Statistical Analysis  [PDF]
Panagiotis Koulelis
Open Journal of Business and Management (OJBM) , 2016, DOI: 10.4236/ojbm.2016.42027
Abstract: During the economic crisis in Greece, the national forest sector wounded by a serious decline in demand. The national forest sector faced an important decline in forest products consumption. The paper examines the quantitative changes in the above consumption regarding several wood products categories. The results indicated that a very important decline in consumption per capita took place after 2008. Moreover, an unwanted positive relationship between GDP and the forest products trade deficit is confirmed. During the crisis, the continuant reduction of GDP brings reduction on deficit in trade of forest products while an important increase of exports occurs. However, the results also show that policy makers must act immediately in order to stop the total collapse of the sector.
The Restoration of Fiscal Stability. A Public Choice Approach on the Problem of Public Debt  [PDF]
Panagiotis Evangelopoulos
Theoretical Economics Letters (TEL) , 2018, DOI: 10.4236/tel.2018.82010
Abstract: In contemporary democracy fiscal policy is not employed for the fiscal control of necessary state activities but for generation of deficits which causes the state to feed on itself, expands enormously in the service of special interests and is contrary to the public’s interest in fiscal stability and discipline. Starting from the origin of and the reason for, the classical liberal state, I undertake an analysis of the historical theoretical background of public choice. The development and application of public choice analysis can work towards restoring fiscal stability, especially after the outbreak of the global financial crisis that generated the enormous increases in the public deficit and debt in the developed democracies.
Genome-Wide Associations of Gene Expression Variation in Humans
Barbara E Stranger equal contributor,Matthew S Forrest equal contributor,Andrew G Clark,Mark J Minichiello,Samuel Deutsch,Robert Lyle,Sarah Hunt,Brenda Kahl,Stylianos E Antonarakis,Simon Tavaré,Panagiotis Deloukas ,Emmanouil T Dermitzakis
PLOS Genetics , 2005, DOI: 10.1371/journal.pgen.0010078
Abstract: The exploration of quantitative variation in human populations has become one of the major priorities for medical genetics. The successful identification of variants that contribute to complex traits is highly dependent on reliable assays and genetic maps. We have performed a genome-wide quantitative trait analysis of 630 genes in 60 unrelated Utah residents with ancestry from Northern and Western Europe using the publicly available phase I data of the International HapMap project. The genes are located in regions of the human genome with elevated functional annotation and disease interest including the ENCODE regions spanning 1% of the genome, Chromosome 21 and Chromosome 20q12–13.2. We apply three different methods of multiple test correction, including Bonferroni, false discovery rate, and permutations. For the 374 expressed genes, we find many regions with statistically significant association of single nucleotide polymorphisms (SNPs) with expression variation in lymphoblastoid cell lines after correcting for multiple tests. Based on our analyses, the signal proximal (cis-) to the genes of interest is more abundant and more stable than distal and trans across statistical methodologies. Our results suggest that regulatory polymorphism is widespread in the human genome and show that the 5-kb (phase I) HapMap has sufficient density to enable linkage disequilibrium mapping in humans. Such studies will significantly enhance our ability to annotate the non-coding part of the genome and interpret functional variation. In addition, we demonstrate that the HapMap cell lines themselves may serve as a useful resource for quantitative measurements at the cellular level.
Informal Financing of Small – Medium Enterprise Sector: The Case of Greece  [PDF]
Panagiotis Petrakis, Konstantinos Eleftheriou
Journal of Service Science and Management (JSSM) , 2009, DOI: 10.4236/jssm.2009.24045
Abstract: In this paper, we attempt to find a “channel” through which Greek economy can exhibit a relative “resistance” in a credit crunch. For this purpose, we specify an error correction model so as to test the relationship between corporate bank loans and commercial papers comprised of post-dated cheques and bills of exchange. The results show that corporate bank loans and cheques - bills of exchange are substitutes. This finding combined with the fact that in Greece, the issuance of these papers is positively connected with the informal economic activity which in turn rises during economic downturns, has a strong economic implication regarding the ability of Greek economy to partly “amortize” the shocks connected with the current financial crisis.
On the Ideal Duration of Entrepreneurial Resources Commitment  [PDF]
Panagiotis E. Petrakis
Technology and Investment (TI) , 2010, DOI: 10.4236/ti.2010.11006
Abstract: The paper proposes that the entrepreneur’s perception of time in the form of average ideal duration of entre-preneurial resources commitment is an important personal trait. The entrepreneur develops a particular checking filter for the entrepreneurial involvement on which the evaluation of entrepreneurial opportunities is based. The concept of ideal time dimension of entrepreneurial engagement is crucially related to the de-velopment of structural prototype prevailing in space and time. Three main influences have been located with respect to the formation of duration on entrepreneurial commitment: microeconomic influences, long-term macro-environmental influences and short-term macro-environmental influences.
Trace-Based Analysis of MPEG-4 AVC Video Streams  [PDF]
Kizouris Panagiotis, Papadakis Andreas
Journal of Computer and Communications (JCC) , 2019, DOI: 10.4236/jcc.2019.71004
Abstract: MPEG-4 AVC encoded video streams have been analyzed using video traces and statistical features have been extracted, in the context of supporting efficient deployment of networked and multimedia services. The statistical features include the number of scenes composing the video and the sizes of different types of frames, within the overall trace and each scene. Statistical processing has been performed upon the traces and subsequent fitting upon statistical distributions (Pareto and lognormal). Through the construction of a synthetic trace, based upon this analysis, our selections of statistical distribution have been verified. In addition, different types of content, in terms of level of activity (quantified as different scene change ratio) have been considered. Through modelling and fitting, the stability of the main statistical parameters has been verified as well as observations on the dependence of these parameters upon the video activity level.
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