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Intra-Storm Pattern Recognition through Fuzzy Clustering

Konstantinos Vantas, Epaminondas Sidiropoulos
2021 Hydrology  
The identification and recognition of temporal rainfall patterns is important and useful not only for climatological studies, but mainly for supporting rainfall–runoff modeling and water resources management. Clustering techniques applied to rainfall data provide meaningful ways for producing concise and inclusive pattern classifications. In this paper, a timeseries of rainfall data coming from the Greek National Bank of Hydrological and Meteorological Information are delineated to independent
more » ... ainstorms and subjected to cluster analysis, in order to identify and extract representative patterns. The computational process is a custom-developed, domain-specific algorithm that produces temporal rainfall patterns using common characteristics from the data via fuzzy clustering in which (a) every storm may belong to more than one cluster, allowing for some equivocation in the data, (b) the number of the clusters is not assumed known a priori but is determined solely from the data and, finally, (c) intra-storm and seasonal temporal distribution patterns are produced. Traditional classification methods include prior empirical knowledge, while the proposed method is fully unsupervised, not presupposing any external elements and giving results superior to the former.
doi:10.3390/hydrology8020057 fatcat:ofgoyhesefcxbg27e5djczmpje

Hysteroscopic treatment of retained placental tissue: a case report

Daniilidis Angelos, Liberis Anastasios, Papandreou Panagiotis, Sidiropoulos Konstantinos, Pratilas George, Dinas Konstantinos
2020 Gynecological Surgery  
Retained placenta tissue is a rare condition, and its diagnosis and surgical treatment are often challenging. Conventionally, the surgical management of such cases is largely performed using blind dilation and curettage. Our case demonstrates that the successful complete removal of retained placental tissues can be achieved with operative hysteroscopy with minimal use of electrosurgery in order to minimize the short-and long-term complications. This was achieved using the loop of the bipolar resectoscope as a curette performing cold dissection.
doi:10.1186/s10397-020-01072-5 fatcat:a32ngesgzvcpdoedbh57g5psvm

ReactomeGSA - Efficient Multi-Omics Comparative Pathway Analysis [article]

Johannes Griss, Guilherme Viteri, Konstantinos Sidiropoulos, Vy Nguyen, Antonio Fabregat, Henning Hermjakob
2020 bioRxiv   pre-print
Pathway analyses are key methods to analyse 'omics experiments. Nevertheless, integrating data from different 'omics technologies and different species still requires considerable bioinformatics knowledge. Here we present the novel ReactomeGSA resource for comparative pathway analyses of multi-omics datasets. ReactomeGSA can be used through Reactome's existing web interface and the novel ReactomeGSA R Bioconductor package with explicit support for scRNA-seq data. Data from different species is
more » ... utomatically mapped to a common pathway space. Public data from ExpressionAtlas and Single Cell ExpressionAtlas can be directly integrated in the analysis. ReactomeGSA thereby greatly reduces the technical barrier for multi-omics, cross-species, comparative pathway analyses. We used ReactomeGSA to characterise the role of B cells in anti-tumour immunity. We compared B cell rich and poor human cancer samples from five TCGA transcriptomics and two CPTAC proteomics studies. There, B cell-rich lung adenocarcinoma samples lack the otherwise present activation through NFkappaB. This may be linked to the presence of a specific subset of tumour associated IgG+ plasma cells that lack NFkappaB activation in scRNA-seq data from human melanoma. This showcases how ReactomeGSA can derive novel biomedical insights by integrating large multi-omics datasets.
doi:10.1101/2020.04.16.044958 fatcat:ge3sjihv6vef5cldmjmicuha4m

The evolution of Greek fauna since classical times

Konstantinos Sidiropoulos, Rosa-Maria Polymeni, Anastasios Legakis
2017 Historical Review  
This article concerns the Greek fauna of classical and late antiquity and changes up to the present day. The main sources for the fauna of antiquity are historical, geographical and zoological texts, as well as descriptions from travellers who visited Greece. The study of the texts of classical and late antiquity was based on the following classical authors: Xenophon, Aristotle, Aristophanes Byzantios, Pliny, Dio Chrysostom, Plutarch, Pausanias and Aelian. Some species that were present in the
more » ... reek fauna of classical and late antiquity, such as the lion and the leopard, are today extinct in Greece, whereas some other species that are now common, such as the cat, the chicken and the peacock, were introduced about that time or a little earlier from other regions. Some other species that are also common today, such as the wild rabbit and the pheasant, were unknown at that time, as they appeared later in Greece from other areas.
doi:10.12681/hr.11559 fatcat:lhnkog3sa5hdre3omsvcokcxjq

Susceptibility of β-Thalassemia Heterozygotes to COVID-19

Sotirios Sotiriou, Athina A. Samara, Dimitra Vamvakopoulou, Konstantinos-Odysseas Vamvakopoulos, Andreas Sidiropoulos, Nikolaos Vamvakopoulos, Michel B. Janho, Konstantinos I. Gourgoulianis, Styllianos Boutlas
2021 Journal of Clinical Medicine  
β-Thalassemia is the most prevalent single gene blood disorder, while the assessment of its susceptibility to coronavirus disease 2019 (COVID-19) warrants it a pressing biomedical priority. Methods: We studied 255 positive COVID-19 participants unvaccinated against severe acute respiratory syndrome–coronavirus 2 (SARS-CoV-2), consecutively recruited during the last trimester of 2020. Patient characteristics including age, sex, current smoking status, atrial fibrillation, chronic respiratory
more » ... ase, coronary disease, diabetes, neoplasia, hyperlipidemia, hypertension, and β-thalassemia heterozygosity were assessed for COVID-19 severity, length of hospitalization, intensive care unit (ICU) admission and mortality from COVID-19. Results: We assessed patient characteristics associated with clinical symptoms, ICU admission, and mortality from COVID-19. In multivariate analysis, severe-critical COVID-19 was strongly associated with male sex (p = 0.023), increased age (p < 0.001), and β-thalassemia heterozygosity (p = 0.002, OR = 2.89). Regarding the requirement for ICU care, in multivariate analysis there was a statistically significant association with hypertension (p = 0.001, OR = 5.12), while β-thalassemia heterozygosity had no effect (p = 0.508, OR = 1.33). Mortality was linked to male sex (p = 0.036, OR = 2.09), increased age (p < 0.001) and β-thalassemia heterozygosity (p = 0.010, OR = 2.79) in multivariate analysis. It is worth noting that hyperlipidemia reduced mortality from COVID-19 (p = 0.008, OR = 0.38). No statistically significant association of current smoking status with patient characteristics studied was observed. Conclusions: Our pilot observations indicate enhanced mortality of β-thalassemia heterozygotes from COVID-19.
doi:10.3390/jcm10163645 pmid:34441941 pmcid:PMC8397014 fatcat:yapltfodr5fjhibglzsvjntici

Rainfall Erosivity and Its Estimation: Conventional and Machine Learning Methods [chapter]

Konstantinos Vantas, Epaminondas Sidiropoulos, Chris Evangelides
2019 Soil Erosion [Working Title]  
A different approach for the estimation of R, in the presence of missing values, was followed by Vantas and Sidiropoulos [47] .  ... 
doi:10.5772/intechopen.85937 fatcat:rzttizlcnrcrfjd6qrcffttyi4

CDNsim

Konstantinos Stamos, George Pallis, Athena Vakali, Dimitrios Katsaros, Antonis Sidiropoulos, Yannis Manolopoulos
2010 ACM Transactions on Modeling and Computer Simulation  
CDNsim may support several Web data management policies Sidiropoulos et al. 2008 ]. -Content outsourcing.  ...  In this framework, CDNsim has been used to evaluate a wide range of policies [Pallis et al. 2005 Sidiropoulos et al. 2008] .  ... 
doi:10.1145/1734222.1734226 fatcat:sws6ksl3zvbnhgowiotgmbcpi4

ReactomeGSA - Efficient Multi-Omics Comparative Pathway Analysis

Johannes Griss, Guilherme Viteri, Konstantinos Sidiropoulos, Vy Nguyen, Antonio Fabregat, Henning Hermjakob
2020 Molecular & Cellular Proteomics  
Pathway analyses are key methods to analyse 'omics experiments. Nevertheless, integrating data from different 'omics technologies and different species still requires considerable bioinformatics knowledge. Here we present the novel ReactomeGSA resource for comparative pathway analyses of multi-omics datasets. ReactomeGSA can be used through Reactome's existing web interface and the novel ReactomeGSA R Bioconductor package with explicit support for scRNA-seq data. Data from different species is
more » ... utomatically mapped to a common pathway space. Public data from ExpressionAtlas and Single Cell ExpressionAtlas can be directly integrated in the analysis. ReactomeGSA greatly reduces the technical barrier for multi-omics, cross-species, comparative pathway analyses. We used ReactomeGSA to characterise the role of B cells in anti-tumour immunity. We compared B cell rich and poor human cancer samples from five of the Cancer Genome Atlas (TCGA) transcriptomics and two of the Clinical Proteomic Tumor Analysis Consortium (CPTAC) proteomics studies. B cell-rich lung adenocarcinoma samples lacked the otherwise present activation through NFkappaB. This may be linked to the presence of a specific subset of tumour associated IgG+ plasma cells that lack NFkappaB activation in scRNA-seq data from human melanoma. This showcases how ReactomeGSA can derive novel biomedical insights by integrating large multi-omics datasets.
doi:10.1074/mcp.tir120.002155 pmid:32907876 pmcid:PMC7710148 fatcat:r3vg6zyu2jfuxoawflgrdwsmo4

Robustness Spatiotemporal Clustering and Trend Detection of Rainfall Erosivity Density in Greece

Konstantinos Vantas, Epaminondas Sidiropoulos, Athanasios Loukas
2019 Water  
Soil erosion is affected by rainfall, among other factors, and it is likely to increase in the future due to climate change impacts, resulting in higher rainfall intensities. This paper evaluates the impact of the missing values ratio on the computation of the rainfall erosivity factor, R, and erosivity density, ED. The paper also investigates the temporal trends and defines regions of Greece with a similar monthly distribution of ED using an unsupervised method. Preprocessed and free from
more » ... and errors rainfall data from 108 stations across Greece were extracted from the Greek National Bank of Hydrological and Meteorological Information. The rainfall data were analyzed and erosive rainfalls were identified, their return period was determined using intensity–duration–frequency curves and R and ED values were computed. The impact of missing data in the computation of annual values of R and ED was investigated using a Monte Carlo simulation. The findings indicated that missing rainfall data resulted in a linear underestimation of R, while ED is more robust. The trends in ED timeseries were evaluated using the Kendall's Tau test and their autocorrelation and partial autocorrelation were computed for a small subset of stations using criteria based on the quality of data. Furthermore, cluster analysis was applied to a larger subset of stations to define regions of Greece with similar monthly distribution of ED. The findings of this study indicate that: (a) ED should be preferred for the assessment of erosivity in Greece over the direct computation of R, (b) ED timeseries are found to be stationary for the majority of the selected stations, in contrast to reported precipitation trends for the same time period, (c) Greece is divided into three clusters/areas of stations with distinct monthly distributions of ED.
doi:10.3390/w11051050 fatcat:cxyrbxcfrvd6zgmafdf6h6akry

Temporal and Elevation Trend Detection of Rainfall Erosivity Density in Greece

Konstantinos Vantas, Epaminondas Sidiropoulos, Athanasios Loukas
2019 Proceedings (MDPI)  
This paper presents certain characteristics of trends in rainfall erosivity density (ED), that have not been so far investigated in depth in the current literature. Raw pluviograph data were acquired from the Greek National Bank of Hydrological and Meteorological Information for 108 stations. Precipitation time series values were cleared from noise and errors, and the ratio of missing values was computed. Erosive rainfalls were identified, their return period was determined using
more » ... ion–frequency (IDF) curves and erosivity values were computed. A Monte Carlo method was utilized to assess the impact of missing values ratio to the computation of annual erosivity (R) and ED values. It was found that the R values are underestimated in a linear way, while ED is more robust against the presence of missing precipitation values. Indicatively, the R values are underestimated by 49%, when only 50% of the erosive rainfall events are used, while at the same time the estimation error of ED is 20%. Using predefined quality criteria for coverage and time length, a subset of stations was selected. Their annual ED values, as well as the samples' autocorrelation and partial autocorrelation functions were computed, in order to investigate the presence of stochastic trends. Subsequently, Kendall's Tau was used in order to yield a measure of the monotonic relationship between annual ED values and time. Finally, the hypothesis that ED values are affected by elevation was tested. In conclusion: (a) It is suggested to compute ED for the assessment of erosivity in Greece instead of the direct computation of R; (b) stationarity of ED was found for the majority of the selected stations, in contrast to reported precipitation trends for the same time period; and (c) the hypothesis that ED values are not correlated to elevation could not be rejected.
doi:10.3390/ecws-3-05814 fatcat:scidrtb3hfei7gnwxlersrt3zi

Estimating Rainfall Erosivity from Daily Precipitation Using Generalized Additive Models

Konstantinos Vantas, Epaminondas Sidiropoulos, Chris Evangelides
2020 Environmental Sciences Proceedings  
[12] compared the results from deep neural networks to empirical equations on the estimation of R, and Vantas and Sidiropoulos [14] evaluated the use of Bayesian neural networks on the estimation  ... 
doi:10.3390/environsciproc2020002021 fatcat:dfs3ipvv5fflvl6o3mcstoztfy

Laser Scanners Technology Applications–The Case of Church of Holy Trinity and Figure of Panagia Pafsolipi, Heybeliada, Turkey

Andreas Sidiropoulos, Konstantinos Lakakis, Konstantinos Tokmakidis
2014 Civil engineering and architecture  
Laser scanning is a method commonly used to geometric documentation of monuments and historical landmarks. Laser scanners, as surveying instruments, combine principals of the sciences of topography and photogrammetry. The purpose of the paper is to evaluate a group of data collected using a laser scanner, concerning the attribution of geometry while drawing. The evaluation was accomplished comparing this group to another group of data, which was used as the reference data and was measured using
more » ... a total station. Two objects of study were used and surveyed. The Greek Orthodox Church which is dedicated to Holy Trinity and is located in Heybeliada of Turkey and a famous figure of Holy Mother holding Jesus, known as Panagia Pafsolipi, which is placed at the interior of the Church. The comparison of the drawings that were exported using both data was satisfying. The divergence that was noticed is of the size of some millimeters. Such differences are acceptable for the most cases of architectural and archaeological documentation. This means that laser scanning, except from the fact that is a fast and efficient way of documentation, also provides products at level of accuracy that is close to the accuracy of the traditional documentation methods.
doi:10.13189/cea.2014.020904 fatcat:sobso24xhfezrmoj5llodvwa2y

Enhanced activity of NLRP3 inflammasome in peripheral blood cells of patients with active rheumatoid arthritis

Christianna Choulaki, Garyfallia Papadaki, Argyro Repa, Eleni Kampouraki, Konstantinos Kambas, Konstantinos Ritis, George Bertsias, Dimitrios T. Boumpas, Prodromos Sidiropoulos
2015 Arthritis Research & Therapy  
Interleukin-1β (IL-1β) is a major inflammatory cytokine, produced predominantly by innate immune cells through NLRP3-inflammasome activation. Both intrinsic and extrinsic danger signals may activate NLRP3. Genetic variations in NLRP3-inflammasome components have been reported to influence rheumatoid arthritis (RA) susceptibility and severity. We sought to assess the activity of NLRP3-inflammasome in patients with active RA compared to healthy individuals. Method: Intracellular protein
more » ... of NLRP3, ASC, pro-and active caspase-1, pro-and active IL-1β was assessed by immunoblotting both at baseline and upon inflammasome activation. NLRP3 function (IL-1β secretion) was assessed upon priming of TLR2 (Pam(3)CysSK(4), TLR3 (poly(I:C)) or TLR4 (LPS) and ATP sequential treatment. We used caspase inhibitors (casp-1, 3/7 and 8) to assess their contribution to IL-1β maturation. All experiments were performed in whole blood cells. Results: Active RA patients (n = 11) expressed higher basal intracellular levels of NLRP3 (p < 0.008), ASC (p < 0.003), active caspase-1 (p < 0.02) and pro-IL-1β (p < 0.001). Upon priming with TLR4 (LPS) and ATP, RA-derived cell extracts (n = 7) displayed increased expression of NLRP3 (p < 0.01) and active caspase-1 (p < 0.001). Secreted IL-1β in culture supernatants from whole blood cells activated with TLR4 (LPS) or TLR3 agonist (poly(I:C)) plus ATP was higher in RA patients (n = 20) versus controls (n = 18) (p < 0.02 for both). Caspase-1 inhibition significantly reduced IL-1β secretion induced by all stimuli, whereas caspase-8 inhibition affected only TLR4 and TLR3 cell priming. Conclusion: Patients with active RA have increased expression of NLRP3 and NLRP3-mediated IL-1β secretion in whole blood cells upon stimulation via TLR3 and TLR4 but not TLR2. In these patients, IL-1β secretion seems to be predominately driven by caspase-1 and caspase-8. Targeting NLRP3 or downstream caspases may be of benefit in suppressing IL-1β production in RA.
doi:10.1186/s13075-015-0775-2 pmid:26385789 pmcid:PMC4575443 fatcat:j67dtlapfvey7nkk2xm43fgcbq

Development and evaluation of a PDA-based teleradiology terminal in thyroid nodule diagnosis

Konstantinos Ninos, Kostopoulos Spiros, Dimitris Glotsos, Pantelis Georgiadis, Konstantinos Sidiropoulos, Nikolaos Dimitropoulos, Ioannis Kalatzis, Dionisis Cavouras
2010 Journal of Telemedicine and Telecare  
We developed a wireless personal digital assistant (PDA)-based teleradiology terminal which allowed a secure connection to the hospital's Picture Archiving and Communication System (PACS) through the DICOM protocol. Ten members of the hospital's medical staff completed a questionnaire about its mobility, usability, stability, performance and diagnostic efficiency in a real health-care environment. There was a high degree of satisfaction with the system's mobility (mean score 4.1, SD 1.0, on a
more » ... ve-point scale), usability (mean score 4.2, SD 1.1), stability (mean score 3.9, SD 0.4) and performance (mean score 4.2, SD 0.6). The system was evaluated as a tool for providing assistance in diagnosing thyroid nodules from ultrasound images. A total of 144 ultrasound images with thyroid nodules were assessed by an expert. Six image quality attributes were evaluated. The physician concluded that the ultrasound thyroid images on the PDA screen were of similar quality to those displayed on a diagnostic visual display unit screen. However, the expert found difficulties in diagnosing microcalcification, internal echo texture and vascularity. The PDA terminal provided rapid, secure and convenient portable access to PACS images and the image quality was sufficient for diagnostic interpretation of ultrasound images of the thyroid.
doi:10.1258/jtt.2010.090512 pmid:20423934 fatcat:w2ctd6fbqzddlbtj6x5zwfw3la

Extending the Applicability of the Meyer–Peter and Müller Bed Load Transport Formula

Epaminondas Sidiropoulos, Konstantinos Vantas, Vlassios Hrissanthou, Thomas Papalaskaris
2021 Water  
In a following study, Sidiropoulos et al.  ...  Calibration with respect to one parameter only, namely k st , has already been tried (Sidiropoulos et al., 2018) .  ... 
doi:10.3390/w13202817 fatcat:c2t5qgsqincjnco3rmjmpjmhtq
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