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A Deep Q-Learning Agent for the L-Game with Variable Batch Training [article]

Petros Giannakopoulos, Yannis Cotronis
2018 arXiv   pre-print
We employ the Deep Q-Learning algorithm with Experience Replay to train an agent capable of achieving a high-level of play in the L-Game while self-learning from low-dimensional states. We also employ variable batch size for training in order to mitigate the loss of the rare reward signal and significantly accelerate training. Despite the large action space due to the number of possible moves, the low-dimensional state space and the rarity of rewards, which only come at the end of a game, DQL
more » ... successful in training an agent capable of strong play without the use of any search methods or domain knowledge.
arXiv:1802.06225v1 fatcat:v672wwcqwnau7lsun2ua7d63pm

An Update on Sexual Transmission of Zika Virus

Hercules Sakkas, Petros Bozidis, Xenofon Giannakopoulos, Nikolaos Sofikitis, Chrissanthy Papadopoulou
2018 Pathogens  
Zika virus (ZIKV) is a single-stranded RNA virus belonging to the arthropod-borne flaviviruses (arboviruses) which are mainly transmitted by blood-sucking mosquitoes of the genus Aedes. ZIKV infection has been known to be rather asymptomatic or presented as febrile self-limited disease; however, during the last decade the manifestation of ZIKV infection has been associated with a variety of neuroimmunological disorders including Guillain–Barré syndrome, microcephaly and other central nervous
more » ... tem abnormalities. More recently, there is accumulating evidence about sexual transmission of ZIKV, a trait that has never been observed in any other mosquito-borne flavivirus before. This article reviews the latest information regarding the latter and emerging role of ZIKV, focusing on the consequences of ZIKV infection on the male reproductive system and the epidemiology of human-to-human sexual transmission.
doi:10.3390/pathogens7030066 pmid:30081445 fatcat:boupaae4zjb3ppfkqwplti3sla

A Deep Reinforcement Learning Approach to Audio-Based Navigation in a Multi-Speaker Environment [article]

Petros Giannakopoulos, Aggelos Pikrakis, Yannis Cotronis
2021 arXiv   pre-print
In this work we use deep reinforcement learning to create an autonomous agent that can navigate in a two-dimensional space using only raw auditory sensory information from the environment, a problem that has received very little attention in the reinforcement learning literature. Our experiments show that the agent can successfully identify a particular target speaker among a set of N predefined speakers in a room and move itself towards that speaker, while avoiding collision with other
more » ... or going outside the room boundaries. The agent is shown to be robust to speaker pitch shifting and it can learn to navigate the environment, even when a limited number of training utterances are available for each speaker.
arXiv:2105.04488v1 fatcat:zccnole5j5anrenwswbm5zxes4

Radiological findings and the clinical importance of megacalycosis

Christos Kalaitzis, Emmanuel Patris, Evangelia Deligeorgiou, Petros Sountoulides, Athanasios Bantis, Stilianos Giannakopoulos, Stavros Touloupidis
2015 Research and Reports in Urology  
Objective: To describe the radiological f indings and the clinical importance of megacalycosis. Materials and methods: On the basis of a case report and literature review, diagnostic criteria and clinical significance of megacalycosis are presented. Result: Megacalycosis is mostly asymptomatic and is usually discovered either accidentally or as a result of its complications, such as stone formation, flank pain, hematuria, infection, and fever. The renal pelvis, infundibulum, and ureter are not
more » ... ilated. Calyces have a semilunar configuration rather than the conventional triangular or conical form. The tip of each pyramid is flat, and the calyces possess neither fornix nor papillae impressions. The number of calyces is increased compared to the healthy condition, typically from 20-25. The renal parenchyma has a normal width but with a slight narrowing of the renal medulla. The kidney exhibits normal function, in particular with respect to its ability to concentrate the urine. Conclusion: Megacalycosis is a rare, usually unilateral dilatation of the kidney calyces in the presence of a normal, undilated renal pelvis and ureter. Its pathological significance lies in the occurrence of complications.
doi:10.2147/rru.s81519 pmid:26528455 pmcid:PMC4621186 fatcat:rgh2re5b6zdjhpn5s5gmfn7mgq

The impact of endograft type on inflammatory response after endovascular treatment of abdominal aortic aneurysm

Konstantinos G. Moulakakis, Maria Alepaki, George S. Sfyroeras, Constantine N. Antonopoulos, Triantafillos G. Giannakopoulos, John Kakisis, Petros Karakitsos, Christos D. Liapis
2013 Journal of Vascular Surgery  
Objective: To evaluate the impact of endograft type on the inflammatory response after elective endovascular repair of abdominal aortic aneurysms. Methods: From January 2011 to November 2011, we included 100 consecutive patients who underwent elective abdominal aortic aneurysm endovascular repair. Thirteen patients were excluded from the analysis: four with cancer, three with autoimmune disease, two because of recent infection, two who were receiving long-term anti-inflammatory medication, and
more » ... wo because of recent surgery. Temperature, white blood cell count, platelet count, and serum concentrations of cytokines (interleukin [IL]-6, IL-8, and IL-10) were measured preoperatively, 24 hours postoperatively, and 48 hours postoperatively. The study sample was divided into four groups with respect to the type of endograft used: group A, n [ 28 (Anaconda; Sulzer Vascutek, Bad Soden, Germany); group B, n [ 26 (Zenith; Cook Inc, Bloomington, Ind); group C, n [ 23 (Excluder; W. L. Gore and Assoc, Flagstaff, Ariz); and group D, n [ 10 (Endurant; Medtronic, Minneapolis, Minn). Endograft configurations included bifurcated grafts only. Results: Epidemiologic characteristics, atherosclerotic risk factors, type of anesthesia, mean blood loss during surgery, and baseline serum levels of cytokines did not differ among the four groups. Mean elevated temperature was more pronounced postoperatively in group A. Serum levels of IL-6 and IL-10 were significantly higher 24 hours and 48 hours postoperatively compared with preoperative levels in all groups. Patients in group C showed the smallest increase in levels of serum IL-6 and IL-10 at 24 hours and 48 hours postoperatively. Mean difference in cytokine levels after aneurysm exclusion was greater for group A vs group C (P < .01) compared with group A vs B (P < .05). No differences in the mortality and morbidity rates were observed among the four groups. Conclusions: Endograft type appears to influence the inflammatory response after endovascular aortic repair. The postimplantation syndrome was apparent during the first 24 hours and decreased afterward. Anaconda and Zenith endografts induced a more intense inflammatory response. A "milder" inflammatory activation was observed in patients with an Excluder endograft. The postimplantation syndrome was not associated with perioperative adverse clinical events showing a benign course. The possible long-term sequelae of postimplantation syndrome require further investigation. (J Vasc Surg 2013;57:668-77.)
doi:10.1016/j.jvs.2012.09.034 pmid:23317524 fatcat:dpyeozaak5ap7kg5zihwiosq7e

RR20. Inflammatory Response following Endovascular Treatment of Abdominal Aortic Aneurysm: Impact of Endograft Type

Konstantinos G. Moulakakis, Maria Alepaki, Giorgos S. Sfyroeras, Triantafillos G. Giannakopoulos, Constantinos N. Antonopoulos, John Kakisis, Anastasios Papapetrou, Petros Karakitsos, Christos D. Liapis
2012 Journal of Vascular Surgery  
Giannakopoulos 1 , Constantinos N. Antonopoulos 1 , John Kakisis 1 , Anastasios Papapetrou 1 , Petros Karakitsos 2 , Christos D.  ...  Giannakopoulos: Nothing to disclose; J. Kakisis: Nothing to disclose; P. Karakitsos: Nothing to disclose; C. D. Liapis: Nothing to disclose; K. G. Moulakakis: Nothing to disclose; A.  ... 
doi:10.1016/j.jvs.2012.03.229 fatcat:ccs2ed5z4zcqrbugmzf6cu4hny

Volume of new-onset thrombus is associated with the development of postimplantation syndrome after endovascular aneurysm repair

John D. Kakisis, Konstantinos G. Moulakakis, Constantine N. Antonopoulos, Spyridon N. Mylonas, Triantafillos G. Giannakopoulos, George S. Sfyroeras, Petros Karakitsos, Christos D. Liapis
2014 Journal of Vascular Surgery  
Objective: The objective of this study was to evaluate the impact of contrast medium volume, inferior mesenteric artery (IMA) patency, and pre-existing as well as new-onset thrombus on the inflammatory response after elective endovascular aneurysm repair (EVAR). Methods: The study included 87 patients undergoing elective endovascular repair of asymptomatic infrarenal aneurysms between January 2011 and November 2011. The patency of the IMA was determined by preoperative computed tomography
more » ... raphy; the volume of the contrast medium used during the procedure was measured, and the volumes of chronic mural as well as new-onset thrombus were calculated from the preoperative and postoperative computed tomography angiograms with dedicated imaging software. The results were correlated to the occurrence of postimplantation syndrome (PIS) as well as to the main clinical and laboratory components of PIS: fever; increased white blood cell (WBC) count and C-reactive protein (CRP) level; decreased platelet count; and increased interleukin (IL)-6, IL-8, and IL-10 levels. Results: Postoperatively, a statistically significant increase was recorded in the mean values of body temperature, WBCs, CRP, IL-6, IL-8, and IL-10, and a statistically significant decrease was recorded in the number of platelets. After adjustment for endograft type, the volume of new-onset thrombus was found to be significantly correlated with the peak postoperative temperature (b [ .307; P < .05) and the increase in WBC count (b [ .271; P < .05), CRP level (b [ .484; P < .001), and IL-6 level (b [ .288; P < .05). On the contrary, the volume of chronic mural thrombus, the patency of the IMA, and the volume of contrast medium were not found to significantly affect any parameter of the PIS. PIS occurred in 34 patients (39%). Multiple logistic regression analysis showed that both the volume of new-onset thrombus and the type of endograft were independently associated with the development of PIS. Conclusions: The volume of new-onset thrombus is associated with the development of PIS after EVAR, whereas chronic mural thrombus appears to be an inert material. IMA patency and contrast medium volume are irrelevant to the inflammatory response after EVAR. (J Vasc Surg 2014;60:1140-5.)
doi:10.1016/j.jvs.2014.05.041 pmid:24953900 fatcat:g27whto47bbf5i6gugji4rckre

Perforation of the Urinary Bladder Caused by Transurethral Insertion of a Pencil for the Purpose of Masturbation in a 29-Year-Old Female

Athanasios Bantis, Petros Sountoulides, Christos Kalaitzis, Stelios Giannakopoulos, Eleni Agelonidou, Soultana Foutzitzi, Stavros Touloupidis
2010 Case Reports in Medicine  
The urethra is a usual site of introduction of foreign bodies for autoerotic stimulation. We present an unusual case of bladder perforation caused by foreign body that was self-inserted in the urethra and consequently slipped inside the bladder in a 29-year-old female patient with psychiatric disease. The patient was referred to our department for macroscopic hematuria and abdominal pain. Imaging studies revealed the presence of a foreign body in the pelvic area which had perforated the left
more » ... eral wall of the bladder. The foreign body was removed via open cystotomy. In psychiatric patients hematuria and pelvic pain may result from insertion of a foreign body in the bladder usually during masturbation.
doi:10.1155/2010/460385 pmid:20862362 pmcid:PMC2938437 fatcat:23uratr5pnaafdlyniqooqsrfa

A Deep Reinforcement Learning Approach for Audio-based Navigation and Audio Source Localization in Multi-speaker Environments [article]

Petros Giannakopoulos, Aggelos Pikrakis, Yannis Cotronis
2021 arXiv   pre-print
In this work we apply deep reinforcement learning to the problems of navigating a three-dimensional environment and inferring the locations of human speaker audio sources within, in the case where the only available information is the raw sound from the environment, as a simulated human listener placed in the environment would hear it. For this purpose we create two virtual environments using the Unity game engine, one presenting an audio-based navigation problem and one presenting an audio
more » ... ce localization problem. We also create an autonomous agent based on PPO online reinforcement learning algorithm and attempt to train it to solve these environments. Our experiments show that our agent achieves adequate performance and generalization ability in both environments, measured by quantitative metrics, even when a limited amount of training data are available or the environment parameters shift in ways not encountered during training. We also show that a degree of agent knowledge transfer is possible between the environments.
arXiv:2110.12778v3 fatcat:abrnq4gjmfenlkvmp7dmctvy6e

A study on implementing a multithreaded version of the SIRENE detector simulation software for high energy neutrinos

Petros Giannakopoulos, Michail Gkoumas, Ioannis Diplas, Georgios Voularinos, Theofanis Vlachos, Konstantia Balasi, Ekaterini Tzamariudaki, Christos Filippidis, Yiannis Cotronis, Christos Markou, A. Capone, G. De Bonis (+2 others)
2016 EPJ Web of Conferences  
The primary objective of SIRENE is to simulate the response to neutrino events of any type of high energy neutrino telescope. Additionally, it implements different geometries for a neutrino detector and different configurations and characteristics of photo-multiplier tubes (PMTs) inside the optical modules of the detector through a library of C+ + classes. This could be considered a massive statistical analysis of photo-electrons. Aim of this work is the development of a multithreaded version
more » ... the SIRENE detector simulation software for high energy neutrinos. This approach allows utilization of multiple CPU cores leading to a potentially significant decrease in the required execution time compared to the sequential code. We are making use of the OpenMP framework for the production of multithreaded code running on the CPU. Finally, we analyze the feasibility of a GPU-accelerated implementation.
doi:10.1051/epjconf/201611607005 fatcat:jqxyuuq4evbajctoo5wb3fb7ze

Coronary stent fracture in an octogenarian patient: from bad to worse

Andreas S Triantafyllis, Petros N Fountoulakis, Georgios Charalampidis, Konstantinos Kotinas, Pavlos Tsinivizov, Dimitrios Varvarousis, Andreas Giannakopoulos, Sofia Apollonatou, Areti Stefanidou, Stamatios Chatzopoulos, Dimitrios Tsiptsios, Konstantinos Tsamakis (+2 others)
tent fracture represents a rare cause of stent failure especially in the era of new generation coronary drug-eluting stents (DES). It is described as the interruption of stent continuity resulting in increased risk of in-stent restenosis and stent thrombosis and predisposes to repeat revascularization. [1] Although a growing number of octogenarians benefit today from an invasive treatment of coronary artery disease (CAD), this benefit could be lost in frail patients with multiple comorbidities.
more » ... [2] ctogenarians constitute a high-risk population in whom frailty and multiple comorbidities mandate for careful treatment planning. An 84-year-old woman was transferred to the Emergency Department (ED) due to a fall following an episode of acute chest pain with diaphoresis. She reported angina in minimal exertion for the last couple of months, which was relieved with the use of sublingual nitrates. Her medical history included CAD treated with stent implantation in the proximal left anterior descending (LAD) artery seven years ago in the context of a positive stress test, hypertension and dyslipidemia under treatment with aspirin, valsartan, hydrochlorothiazide, metoprolol and atorvastatin. At presentation, blood pressure was 180/90 mmHg, with a heart rate of 75 beats/min in sinus rhythm, and an oxygen saturation of 90% on room air. Physical examination revealed bilateral crackles and a third heart sound (S 3 ) while a painful, shortened
doi:10.11909/j.issn.1671-5411.2021.11.009 pmid:34908931 pmcid:PMC8648541 fatcat:3svmytdgnjcczfir2xw4yga4pm

RR19. Remodeling of Aortic Aneurysm and Aortic Neck on Mid- and Long-term Follow-up after Endovascular Repair with Suprarenal Fixation

Nikolaos Tsilimparis, Anand Dayama, Joseph J. Ricotta
2012 Journal of Vascular Surgery  
Giannakopoulos 1 , Constantinos N. Antonopoulos 1 , John Kakisis 1 , Anastasios Papapetrou 1 , Petros Karakitsos 2 , Christos D.  ... 
doi:10.1016/j.jvs.2012.03.228 fatcat:r5sghjug2reuzn2e3a6sify2ja

Page 7553 of Mathematical Reviews Vol. , Issue 2000j [page]

2000 Mathematical Reviews  
Giannakopoulos, Fotios Giannessi, F. CI RW onc. fan ewcenavenesass Gibson, C. G. Gilardi, Gianni Gilfeather, Frank L.  ...  Hachenberger, Dirk | Hacia, Lechostaw Hadjicostas, Petros Hadjigeorgiou, R. I Hadjisavvas, Nicolas Haefner, Jeremy Haeusler, Erich Hafez, M. M Haffaf, Hafid .  ... 

RR18. Helical Endostaple Fixation Blunts Aortic Neck Dilatation after Endovascular Aortic Aneurysm Repair

Wadi Gomero-Cure, Manish Mehta, Ronald M. Fairman, John P. Henretta, Marc H. Glickman, David H. Deaton
2012 Journal of Vascular Surgery  
Giannakopoulos 1 , Constantinos N. Antonopoulos 1 , John Kakisis 1 , Anastasios Papapetrou 1 , Petros Karakitsos 2 , Christos D.  ... 
doi:10.1016/j.jvs.2012.03.227 fatcat:h7nonqlszzannffhcmubwh2f6i

Thanks to all those who reviewed for Journal of Medical Case Reports in 2014

Michael R Kidd
2015 Journal of Medical Case Reports  
Georgopoulos Greece Mehdi Ghasemi USA Stilianos Giannakopoulos Greece Paul Gibson Canada Don Gilden USA Ritu Gill USA Matteo Giorgi Italy Olga Giouleme Greece Stefano Giulieri  ...  Arabia Rakesh Garg India Enrique Garrido UK Bogdan Gaspar Romania Amy Gassama Sow Senegal Danielle Gatti USA Elzbieta Gawrych Poland Roman Gebauer Germany Ralph George Canada Petros  ... 
doi:10.1186/s13256-015-0531-x fatcat:27z7awj46nhsjazgqcvx5f6yki
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