Ioannis Giannakopoulos - Academia.edu (original) (raw)

Papers by Ioannis Giannakopoulos

2014 IEEE International Conference on Big Data (Big Data), 2014

2015 IEEE International Conference on Cloud Engineering, 2015

In this work we address the problem of predicting the performance of a complex application deploy... more In this work we address the problem of predicting the performance of a complex application deployed over virtualized resources. Cloud computing has enabled numerous companies to develop and deploy their applications over cloud infrastructures for a wealth of reasons including (but not limited to) decrease costs, avoid administrative effort, rapidly allocate new resources, etc. Virtualization however, adds an extra layer in the software stack, hardening the prediction of the relation between the resources and the application performance, which is a key factor for every industry. To address this challenge we propose PANIC, a system which obtains knowledge for the application by actually deploying it over a cloud infrastructure and then, approximating the performance of the application for the all possible deployment configurations. The user of PANIC defines a set of resources along with their respective values in which her application can be deployed to and then the system samples the deployment space formed by all the combinations of the resources, deploys the application in some representative points and utilizes a wealth of approximation techniques to predict the behavior of the application in the remainder space. The experimental evaluation has indicated that a small portion of the possible deployment configurations is enough to create profiles with high accuracy for three real world applications.

Proceedings of the 2015 ACM SIGMOD International Conference on Management of Data, 2015

The amount of social networking data that is being produced and consumed daily is huge and it is ... more The amount of social networking data that is being produced and consumed daily is huge and it is constantly increasing. A user's digital footprint coming from social networks or mobile devices, such as comments and check-ins contains valuable information about his preferences. The collection and analysis of such footprints using also information about the users' friends and their footprints offers many opportunities in areas such as personalized search, recommendations, etc. When the size of the collected data or the complexity of the applied methods increases, traditional storage and processing systems are not enough and distributed approaches are employed. In this work, we present MoDis-SENSE, an open-source distributed platform that provides personalized search for points of interest and trending events based on the user's social graph by combining spatio-textual user generated data. The system is designed with scalability in mind, it is built using a combination of latest state-ofthe art big data frameworks and its functionality is offered through easy to use mobile and web clients which support the most popular social networks. We give an overview of its architectural components and technologies and we evaluate its performance and scalability using different query types over various cluster sizes. Using the web or mobile clients, users are allowed to register themselves with their own social network credentials, perform socially enhanced queries for POIs, browse the results and explore the automatic blog creation functionality that is extracted by analyzing already collected GPS traces.

Emerging Research in Cloud Distributed Computing Systems

Today's complex cloud applications are composed of multiple components executed in multi-cloud en... more Today's complex cloud applications are composed of multiple components executed in multi-cloud environments. For such applications, the possibility to manage and control their cost, quality, and resource elasticity is of paramount importance. However, given that the cost of different services offered by cloud providers can vary a lot with their quality/performance, elasticity controllers must consider not only

Japanese journal of infectious diseases, 2008

The purpose of the present study was to compare the incidence of childhood meningitis in regions ... more The purpose of the present study was to compare the incidence of childhood meningitis in regions with fewer than 2,000 inhabitants (rural regions) and regions with more than 2,000 inhabitants (urban regions) in the prefecture of Achaia in Western Greece during 1991-2005. Included were all 555 children hospitalized for meningitis. The criteria for bacterial meningitis were (i) positive blood/cerebralspinal fluid (CSF) culture, Gram stain, or latex agglutination and/or (ii) increased beta-glucuronidase in CSF. In case of suspected bacterial meningitis, the following findings were considered: compatible clinical and laboratory findings, and whether or not a cure was achieved with antibiotic treatment and finally resulted in negative cultures. In cases of suspected viral meningitis, compatible clinical and laboratory findings were considered, together with observation of a cure without antibiotic treatment. Only 28 of 555 meningitis patients were from rural regions. The incidence per 10...

Japanese journal of infectious diseases, 2006

The purpose of this study was to evaluate clinical and laboratory findings, treatment modalities ... more The purpose of this study was to evaluate clinical and laboratory findings, treatment modalities and final outcomes of brucellosis in children and to compare our data with those of other studies performed in Greece. Fifty-two children treated for brucellosis in the Department of Pediatrics during the decade 1995-2004 were analyzed. Of the 52 children, 47 were reexamined during July 2005. Fever, arthritis or arthralgia, hepatomegaly and splenomegaly were the main findings. Young children had positive blood cultures and lower or negative antibody titers statistically significantly more often than did older children. Brucella abortus was isolated in 9 of 18 patients with positive blood cultures. Antibiotic treatment lasted for 28 days on average. There were no complications or relapses, except one, and the final outcomes were excellent.

2014 IEEE International Conference on Big Data (Big Data), 2014

One of the main promises of the cloud computing paradigm is the ability to scale resources on-dem... more One of the main promises of the cloud computing paradigm is the ability to scale resources on-demand. This feature characterizes the cloud era, where the overhead of early expenditure for infrastructure is eliminated. Innovative services are thus able to enter the market quicker and adopt faster to new challenges and user demand. One of the main aspects of this on-demand nature is the concept of elasticity, i.e., the ability of autonomously provision and de-provision resources by reacting to changes in the incoming load. An elastic service is able to operate with an optimal cost by expanding and contracting its used resources at runtime and according to demand. This does not only minimizes running cost, but also avoids disruptive outages due to spikes in service usage. While the various layers comprising a cloud service can be scaled, this does not happen in a unified manner. The vision of CELAR is to provide a fully integrated software stack that manages resource allocation for cloud applications in an autonomous, efficient and generic manner. In order to achieve that, CELAR incorporates novel methodologies for describing cloud applications, monitoring the use of various resources, evaluating cost, taking informed decisions and interacting with the underlying cloud infrastructure. Our goal is twofold. On the one hand is developing the methodologies for achieving multi-grained, automatic elasticity control on both application and infrastructure level. On the other hand is developing the open-source tools that implement those methods in an integrated manner. Hereby we present an overview of the CELAR platform, explaining its architectural components and some basic workflows that show how they interact in order to achieve the core functionalities.

Knee Surgery, Sports Traumatology, Arthroscopy, 2005

International Journal of Cardiology, 2011

Background: Tobacco use in pregnancy is considered a human developmental toxicant and potential t... more Background: Tobacco use in pregnancy is considered a human developmental toxicant and potential teratogen. The aim of the study was to test for a possible association between periconceptional tobacco smoking and congenital heart disease (CHD) in the neonatal period. Methods: Maternal and infant characteristics of 157 neonates diagnosed with CHD at the University of Patras Medical School were collected and were compared with 208 normal neonates (aged 1-28 days) that were referred for echocardiography during a specified 3-year period. Results: In neonates with CHD 64 of 157 mothers (40.8%) reported smoking in pregnancy, whereas in the control group 41 of 208 mothers (19.7%) were smokers (p = 0.000). Logistic regression analysis with pregestational diabetes, history of influenza-like illness in the first trimester, therapeutic drug exposure in pregnancy, maternal age, parity, family history of CHD, infant gender, prematurity and paternal smoking, as potential confounding factors showed that periconceptional tobacco smoking was associated with increased risk of CHD in the offspring (OR = 2.750, 95% CI = 1.659-4.476, p = 0.00001). The incidence of neonatal heart disease in women who were non-smokers or smoked 1-10 and ≥11 cigarettes per day increased with the level of fetal tobacco exposure (35.8% versus 55.3% versus 64.3%, x 2 -test = 20.303, p = 0.000), suggesting a dose effect. Conclusions: The results of the study are indicative of an association between periconceptional tobacco exposure and increased risk of CHD in the neonatal period. The potential role of gestational smoking as a risk factor for specific heart defect subgroups requires the conduction of large population based epidemiological studies.

European Journal of Pediatrics, 2008

This manuscript reports on two very low birth weight premature infants with respiratory distress,... more This manuscript reports on two very low birth weight premature infants with respiratory distress, receiving parenteral nutrition and broad-spectrum antibiotics for about 3 weeks, who developed Candida albicans sepsis associated with fungal mycoses and endocarditis, despite treatment with Amphotericin B and Caspofungin. On days 40 and 47, respectively, antifungal therapy was modified to liposomal Amphotericin B combined with Fluconazole 6 mg/kg/day for 4 weeks, resulting in complete resolution of the mycetomas. Our observations suggest that the combination of liposomal Amphotericin B with Fluconazole is able to result in complete resolution of cardiac mycetomas in preterm infants.

European Journal of Pediatrics, 2010

The aim of this study was to evaluate indices of respiratory failure in terms of their ability to... more The aim of this study was to evaluate indices of respiratory failure in terms of their ability to predict respiratory impairment and need for ventilatory support in late-preterm neonates with respiratory distress. Arterial blood gas data during the first 12 postnatal hours or until intubation were recorded in 155 neonates with gestational age 34 0/7-36 6/7 weeks admitted in the NICU with respiratory distress between January 2006 and June 2008. Alveolar-arterial oxygen tension difference (A-aDO 2), arterial to alveolar oxygen tension ratio (a/A ratio), and partial arterial oxygen tension to inspired oxygen fraction ratio (PaO 2 /FiO 2) were calculated. Considering the worst single value of each parameter, receiver operating characteristic curve analyses and area under the curve (AUC) comparisons were used to evaluate their predictive performance. Fifty-five neonates (35.5%) required mechanical ventilation. The predictive performances of the maximum A-aDO 2 (AUC 0.97), minimum a/A ratio (AUC 0.95), and minimum PaO 2 /FiO 2 (AUC 0.95) were similar. The A-aDO 2 at a threshold of >200 mmHg proved to be more effective than the other parameters, having excellent positive and negative likelihood ratios of 24.5 and 0.02, respectively. This threshold was achieved by 98.25% of the neonates who developed respiratory failure at a median of 3 h before the ventilatory support to be definitely decided. Composite indices, such as A-aDO 2 , a/A ratio, and PaO 2 /FiO 2 , can reasonably predict respiratory failure in late-preterm neonates with respiratory distress, allowing for closer monitoring, early medical intervention, or transfer to a level III neonatal unit.

2014 IEEE International Conference on Big Data (Big Data), 2014

2015 IEEE International Conference on Cloud Engineering, 2015

In this work we address the problem of predicting the performance of a complex application deploy... more In this work we address the problem of predicting the performance of a complex application deployed over virtualized resources. Cloud computing has enabled numerous companies to develop and deploy their applications over cloud infrastructures for a wealth of reasons including (but not limited to) decrease costs, avoid administrative effort, rapidly allocate new resources, etc. Virtualization however, adds an extra layer in the software stack, hardening the prediction of the relation between the resources and the application performance, which is a key factor for every industry. To address this challenge we propose PANIC, a system which obtains knowledge for the application by actually deploying it over a cloud infrastructure and then, approximating the performance of the application for the all possible deployment configurations. The user of PANIC defines a set of resources along with their respective values in which her application can be deployed to and then the system samples the deployment space formed by all the combinations of the resources, deploys the application in some representative points and utilizes a wealth of approximation techniques to predict the behavior of the application in the remainder space. The experimental evaluation has indicated that a small portion of the possible deployment configurations is enough to create profiles with high accuracy for three real world applications.

Proceedings of the 2015 ACM SIGMOD International Conference on Management of Data, 2015

The amount of social networking data that is being produced and consumed daily is huge and it is ... more The amount of social networking data that is being produced and consumed daily is huge and it is constantly increasing. A user's digital footprint coming from social networks or mobile devices, such as comments and check-ins contains valuable information about his preferences. The collection and analysis of such footprints using also information about the users' friends and their footprints offers many opportunities in areas such as personalized search, recommendations, etc. When the size of the collected data or the complexity of the applied methods increases, traditional storage and processing systems are not enough and distributed approaches are employed. In this work, we present MoDis-SENSE, an open-source distributed platform that provides personalized search for points of interest and trending events based on the user's social graph by combining spatio-textual user generated data. The system is designed with scalability in mind, it is built using a combination of latest state-ofthe art big data frameworks and its functionality is offered through easy to use mobile and web clients which support the most popular social networks. We give an overview of its architectural components and technologies and we evaluate its performance and scalability using different query types over various cluster sizes. Using the web or mobile clients, users are allowed to register themselves with their own social network credentials, perform socially enhanced queries for POIs, browse the results and explore the automatic blog creation functionality that is extracted by analyzing already collected GPS traces.

Emerging Research in Cloud Distributed Computing Systems

Today's complex cloud applications are composed of multiple components executed in multi-cloud en... more Today's complex cloud applications are composed of multiple components executed in multi-cloud environments. For such applications, the possibility to manage and control their cost, quality, and resource elasticity is of paramount importance. However, given that the cost of different services offered by cloud providers can vary a lot with their quality/performance, elasticity controllers must consider not only

Japanese journal of infectious diseases, 2008

The purpose of the present study was to compare the incidence of childhood meningitis in regions ... more The purpose of the present study was to compare the incidence of childhood meningitis in regions with fewer than 2,000 inhabitants (rural regions) and regions with more than 2,000 inhabitants (urban regions) in the prefecture of Achaia in Western Greece during 1991-2005. Included were all 555 children hospitalized for meningitis. The criteria for bacterial meningitis were (i) positive blood/cerebralspinal fluid (CSF) culture, Gram stain, or latex agglutination and/or (ii) increased beta-glucuronidase in CSF. In case of suspected bacterial meningitis, the following findings were considered: compatible clinical and laboratory findings, and whether or not a cure was achieved with antibiotic treatment and finally resulted in negative cultures. In cases of suspected viral meningitis, compatible clinical and laboratory findings were considered, together with observation of a cure without antibiotic treatment. Only 28 of 555 meningitis patients were from rural regions. The incidence per 10...

Japanese journal of infectious diseases, 2006

The purpose of this study was to evaluate clinical and laboratory findings, treatment modalities ... more The purpose of this study was to evaluate clinical and laboratory findings, treatment modalities and final outcomes of brucellosis in children and to compare our data with those of other studies performed in Greece. Fifty-two children treated for brucellosis in the Department of Pediatrics during the decade 1995-2004 were analyzed. Of the 52 children, 47 were reexamined during July 2005. Fever, arthritis or arthralgia, hepatomegaly and splenomegaly were the main findings. Young children had positive blood cultures and lower or negative antibody titers statistically significantly more often than did older children. Brucella abortus was isolated in 9 of 18 patients with positive blood cultures. Antibiotic treatment lasted for 28 days on average. There were no complications or relapses, except one, and the final outcomes were excellent.

2014 IEEE International Conference on Big Data (Big Data), 2014

One of the main promises of the cloud computing paradigm is the ability to scale resources on-dem... more One of the main promises of the cloud computing paradigm is the ability to scale resources on-demand. This feature characterizes the cloud era, where the overhead of early expenditure for infrastructure is eliminated. Innovative services are thus able to enter the market quicker and adopt faster to new challenges and user demand. One of the main aspects of this on-demand nature is the concept of elasticity, i.e., the ability of autonomously provision and de-provision resources by reacting to changes in the incoming load. An elastic service is able to operate with an optimal cost by expanding and contracting its used resources at runtime and according to demand. This does not only minimizes running cost, but also avoids disruptive outages due to spikes in service usage. While the various layers comprising a cloud service can be scaled, this does not happen in a unified manner. The vision of CELAR is to provide a fully integrated software stack that manages resource allocation for cloud applications in an autonomous, efficient and generic manner. In order to achieve that, CELAR incorporates novel methodologies for describing cloud applications, monitoring the use of various resources, evaluating cost, taking informed decisions and interacting with the underlying cloud infrastructure. Our goal is twofold. On the one hand is developing the methodologies for achieving multi-grained, automatic elasticity control on both application and infrastructure level. On the other hand is developing the open-source tools that implement those methods in an integrated manner. Hereby we present an overview of the CELAR platform, explaining its architectural components and some basic workflows that show how they interact in order to achieve the core functionalities.

Knee Surgery, Sports Traumatology, Arthroscopy, 2005

International Journal of Cardiology, 2011

Background: Tobacco use in pregnancy is considered a human developmental toxicant and potential t... more Background: Tobacco use in pregnancy is considered a human developmental toxicant and potential teratogen. The aim of the study was to test for a possible association between periconceptional tobacco smoking and congenital heart disease (CHD) in the neonatal period. Methods: Maternal and infant characteristics of 157 neonates diagnosed with CHD at the University of Patras Medical School were collected and were compared with 208 normal neonates (aged 1-28 days) that were referred for echocardiography during a specified 3-year period. Results: In neonates with CHD 64 of 157 mothers (40.8%) reported smoking in pregnancy, whereas in the control group 41 of 208 mothers (19.7%) were smokers (p = 0.000). Logistic regression analysis with pregestational diabetes, history of influenza-like illness in the first trimester, therapeutic drug exposure in pregnancy, maternal age, parity, family history of CHD, infant gender, prematurity and paternal smoking, as potential confounding factors showed that periconceptional tobacco smoking was associated with increased risk of CHD in the offspring (OR = 2.750, 95% CI = 1.659-4.476, p = 0.00001). The incidence of neonatal heart disease in women who were non-smokers or smoked 1-10 and ≥11 cigarettes per day increased with the level of fetal tobacco exposure (35.8% versus 55.3% versus 64.3%, x 2 -test = 20.303, p = 0.000), suggesting a dose effect. Conclusions: The results of the study are indicative of an association between periconceptional tobacco exposure and increased risk of CHD in the neonatal period. The potential role of gestational smoking as a risk factor for specific heart defect subgroups requires the conduction of large population based epidemiological studies.

European Journal of Pediatrics, 2008

This manuscript reports on two very low birth weight premature infants with respiratory distress,... more This manuscript reports on two very low birth weight premature infants with respiratory distress, receiving parenteral nutrition and broad-spectrum antibiotics for about 3 weeks, who developed Candida albicans sepsis associated with fungal mycoses and endocarditis, despite treatment with Amphotericin B and Caspofungin. On days 40 and 47, respectively, antifungal therapy was modified to liposomal Amphotericin B combined with Fluconazole 6 mg/kg/day for 4 weeks, resulting in complete resolution of the mycetomas. Our observations suggest that the combination of liposomal Amphotericin B with Fluconazole is able to result in complete resolution of cardiac mycetomas in preterm infants.

European Journal of Pediatrics, 2010

The aim of this study was to evaluate indices of respiratory failure in terms of their ability to... more The aim of this study was to evaluate indices of respiratory failure in terms of their ability to predict respiratory impairment and need for ventilatory support in late-preterm neonates with respiratory distress. Arterial blood gas data during the first 12 postnatal hours or until intubation were recorded in 155 neonates with gestational age 34 0/7-36 6/7 weeks admitted in the NICU with respiratory distress between January 2006 and June 2008. Alveolar-arterial oxygen tension difference (A-aDO 2), arterial to alveolar oxygen tension ratio (a/A ratio), and partial arterial oxygen tension to inspired oxygen fraction ratio (PaO 2 /FiO 2) were calculated. Considering the worst single value of each parameter, receiver operating characteristic curve analyses and area under the curve (AUC) comparisons were used to evaluate their predictive performance. Fifty-five neonates (35.5%) required mechanical ventilation. The predictive performances of the maximum A-aDO 2 (AUC 0.97), minimum a/A ratio (AUC 0.95), and minimum PaO 2 /FiO 2 (AUC 0.95) were similar. The A-aDO 2 at a threshold of >200 mmHg proved to be more effective than the other parameters, having excellent positive and negative likelihood ratios of 24.5 and 0.02, respectively. This threshold was achieved by 98.25% of the neonates who developed respiratory failure at a median of 3 h before the ventilatory support to be definitely decided. Composite indices, such as A-aDO 2 , a/A ratio, and PaO 2 /FiO 2 , can reasonably predict respiratory failure in late-preterm neonates with respiratory distress, allowing for closer monitoring, early medical intervention, or transfer to a level III neonatal unit.