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Dry-grinded ultrafine cements hydration. physicochemical and microstructural characterization
Kontoleontos, Foteini;Tsakiridis, Petros;Marinos, Apostolos;Katsiotis, Nikolaos;Kaloidas, Vasileios;Katsioti, Margarita;
Materials Research , 2013, DOI: 10.1590/S1516-14392013005000014
Abstract: the aim of the present research work was the evaluation of the physicochemical and microstructural properties of two ultrafine cements, produced by dry grinding of a commercial cem i 42.5n cement. the effect of grinding on particle size distribution was determined by laser scattering analyzer. all cements were tested for initial and final setting times, consistency of standard paste, soundness, flow of normal mortar and compressive strengths after 1, 2, 7 and 28 days. the effect of the fineness on the heat of hydration was also investigated. the hydration products were determined by x-ray diffraction analysis and by fourier transform infrared spectroscopy, at 1, 2, 7 and 28 days. the microstructure of the hardened cement pastes and their morphological characteristics were examined by scanning electron microscopy. porosity and pore size distribution were evaluated by mercury intrusion porosimetry. the effects of greater fineness on compressive strengths were evident principally at early ages. after the first 24 hours of hydration, the compressive strength of the finest cements was about 3 times higher (over 48 mpa) than the corresponding of cem i 42.5n (15.1 mpa).
The Avascular Tumour Growth in the Presence of Inhomogeneous Physical Parameters Imposed from a Finite Spherical Nutritive Environment
Foteini Kariotou,Panayiotis Vafeas
International Journal of Differential Equations , 2012, DOI: 10.1155/2012/175434
Abstract: A well-known mathematical model of radially symmetric tumour growth is revisited in the present work. Under this aim, a cancerous spherical mass lying in a finite concentric nutritive surrounding is considered. The host spherical shell provides the tumor with vital nutrients, receives the debris of the necrotic cancer cells, and also transmits to the tumour the pressure imposed on its exterior boundary. We focus on studying the type of inhomogeneity that the nutrient supply and the pressure field imposed on the host exterior boundary, can exhibit in order for the spherical structure to be supported. It turns out that, if the imposed fields depart from being homogeneous, only a special type of interrelated inhomogeneity between nutrient and pressure can secure the spherical growth. The work includes an analytic derivation of the related boundary value problems based on physical conservation laws and their analytical treatment. Implementations in cases of special physical interest are examined, and also existing homogeneous results from the literature are fully recovered. 1. Introduction Mathematical modelling of cancer tumour growth helps in understanding the mechanisms underlying the phenomenon in many ways. The main idea is that modelling physical hypotheses in mathematical terms, a biological phenomenon, such as tumour growth, is approached by a mathematical problem. Analytic and numerical or hybrid methods, applied to the problem studied, lead to conclusions on the solution of the problem. The conclusions are interpreted in biological terms that are subject to evaluation with respect to experimental evidence. Thus, mathematical modelling may potentially offer new perspective in the research directions of biological procedures. As cancer research and the related technology improved, an increasing amount of experimental data was produced, which made it hard to interpret. At the same time, mathematical models begun to develop at the aid of understanding the crucial parameters involved in tumour’s evolution [1, 2]. In the early years, mathematical models focused mainly on the avascular phase of the tumour’s development. This phase corresponds to the stages right after tumorigenesis and ends with a steady state, where the tumour’s volume gain, due to the new cancerous cells birth, balance the volume loss from the cells’ death and disintegration. In order for the tumour’s evolution to proceed, new phenomena, as angiogenesis, have to take place and the vascular phase may begin. In this phase, the tumour has developed a vascular net around it that provides
Employment Status and Job-Studies Relevance of Social Science Graduates: The Experience from a Greek Public University
Aglaia G. Kalamatianou,Foteini Kougioumoutzaki
International Journal of Economic Sciences and Applied Research , 2012,
Abstract: Research on social science graduates' employment prospects reaches contradictor conclusions intensifying the scepticism on the value of these disciplines in the labour market. The paper examines two important labour market outcomes of these graduates, employment status and job-studies relevance taking into account gender and time of graduation. This is put into the Greek context, then examined further in a case study on graduates of a public University thatexclusively serves social sciences. Results indicate deterioration of the graduates' employment opportunities, lower employment status of female graduates, and persistence of a high degree of 'job-studies no relevance' over time.
Secure Telemedicine: Biometrics for Remote and Continuous Patient Verification
Foteini Agrafioti,Francis M. Bui,Dimitrios Hatzinakos
Journal of Computer Networks and Communications , 2012, DOI: 10.1155/2012/924791
Abstract: The technological advancements in the field of remote sensing have resulted in substantial growth of the telemedicine industry. While health care practitioners may now monitor their patients’ well-being from a distance and deliver their services remotely, the lack of physical presence introduces security risks, primarily with regard to the identity of the involved parties. The sensing apparatus, that a patient may employ at home, collects and transmits vital signals to medical centres which respond with treatment decisions despite the lack of solid authentication of the transmitter’s identity. In essence, remote monitoring increases the risks of identity fraud in health care. This paper proposes a biometric identification solution suitable for continuous monitoring environments. The system uses the electrocardiogram (ECG) signal in order to extract unique characteristics which allow to discriminate users. In security, ECG falls under the category of medical biometrics, a relatively young but promising field of biometric security solutions. In this work, the authors investigate the idiosyncratic properties of home telemonitoring that may affect the ECG signal and compromise security. The effects of psychological changes on the ECG waveform are taken into consideration for the design of a robust biometric system that can identify users based on cardiac signals despite physical or emotional variations. 1. Introduction For a number of severe diseases such as diabetes, hypertension, or respiratory disorders, where hospitalization might not always be justified or needed, home care is traditionally preferred. Moreover, the visit of a medical practitioner to the patient’s home is not necessarily an efficient solution either. This is because (i) the high health care costs for this service are undesirable; (ii) it may be infeasible for the personnel to reach highly rural areas; and (iii) monitoring is usually required on a continuous basis, rather than per visit. Home telemonitoring is now a reality, addressing the above problem very effectively, that is, it is not only cost-efficient but can also reach isolated communities and allow for 24?hr reporting on the patient’s status. Nevertheless, the widespread utilization of telemonitoring increases the risk of identity fraud in health care. Due to the lack of physical presence at the time of collection of the medical information (e.g., vital signals), the identity of the user that transmits the respective information is uncertain. Typically, every monitoring device is assigned with a unique ID (e.g., a serial code)
Subdiagnóstico de doen as respiratórias durante uma desacelera o econ mica e necessidade do uso da espirometria como teste de triagem Underdiagnosis of respiratory diseases during an economic downturn and the need for spirometry as a screening test
Filio Kotrogianni,Foteini Malli,Konstantinos I Gourgoulianis
Jornal Brasileiro de Pneumologia , 2013,
Abstract:
Simulations for a next-generation UHECR observatory
Foteini Oikonomou,Kumiko Kotera,Filipe B. Abdalla
Physics , 2014, DOI: 10.1088/1475-7516/2015/01/030
Abstract: We explore the potential of a future, ultra-high energy cosmic ray (UHECR) experiment, that is able to overcome the limitation of low statistics, to detect anisotropy in the arrival directions of UHECRs. We concentrate on the lower energy range of future instruments (E > 50 EeV), where, if the UHECR source number density is not too low, the sources should be numerous enough to imprint a clustering pattern in the sky, and thus possibly in the UHECR arrival directions. Under these limits, the anisotropy signal should be dominated by the clustering of astrophysical sources per-se in the large-scale structures, and not the clustering of events around individual sources. We study the potential for a statistical discrimination between different astrophysical models which we parametrise by the number density of UHECR sources, the possible bias of the UHECR accelerators with respect to the galaxy distribution, and the unknown fraction of UHECRs that have been deflected by large angles. We demonstrate that an order-of-magnitude increase in statistics would allow to discriminate between a variety of astrophysical models, provided that a sub-sample of light elements can be extracted, and that it represents at least ~70% of the overall flux, sensitive to the UHECR source number density. Even without knowledge of the composition, an anisotropy at the 99.7% level should be detectable when the number of detected events exceeds 2000 beyond 50 EeV, as long as the composition is proton dominated, and the number density of UHECR sources is relatively high. If the UHECR sources are strongly biased relative to the galaxy distribution, as are for example galaxy clusters, an anisotropy at the 99.7% should be detectable once the number of detected events exceeds 1000, if the fraction of protons at the highest energies is ~60% or higher.
Synchrotron pair halo and echo emission from blazars in the cosmic web: application to extreme TeV blazars
Foteini Oikonomou,Kohta Murase,Kumiko Kotera
Physics , 2014, DOI: 10.1051/0004-6361/201423798
Abstract: High frequency peaked high redshift blazars, are extreme in the sense that their spectrum is particularly hard and peaks at TeV energies. Standard leptonic scenarios require peculiar source parameters and/or a special setup in order to account for these observations. Electromagnetic cascades seeded by ultra-high energy cosmic rays (UHECR) in the intergalactic medium have also been invoked, assuming a very low intergalactic magnetic field (IGMF). Here we study the synchrotron emission of UHECR secondaries produced in blazars located in magnetised environments, and show that it can provide an alternative explanation to these challenged channels, for sources embedded in structured regions with magnetic field strengths of the order of $10^{-7}$ G. To demonstrate this, we focus on three extreme blazars: 1ES 0229+200, RGB J0710+591, and 1ES 1218+304. We model the expected gamma-ray signal from these sources through a combination of numerical Monte Carlo simulations and solving the kinetic equations of the particles in our simulations, and explore the UHECR source and intergalactic medium parameter space to test the robustness of the emission. We show that the generated synchrotron pair halo/echo flux at the peak energy is not sensitive to variations in the overall IGMF strength. This signal is unavoidable in contrast to the inverse Compton pair halo/echo intensity, which is appealing in view of the large uncertainties on the IGMF in voids of large scale structure. It is also shown that the variability of blazar gamma-ray emission can be accommodated by the synchrotron emission of secondary products of UHE neutral beams if these are emitted by UHECR accelerators inside magnetised regions.
Building and Maintaining Halls of Fame over a Database
Foteini Alvanaki,Sebastian Michel,Aleksandar Stupar
Computer Science , 2012,
Abstract: Halls of Fame are fascinating constructs. They represent the elite of an often very large amount of entities---persons, companies, products, countries etc. Beyond their practical use as static rankings, changes to them are particularly interesting---for decision making processes, as input to common media or novel narrative science applications, or simply consumed by users. In this work, we aim at detecting events that can be characterized by changes to a Hall of Fame ranking in an automated way. We describe how the schema and data of a database can be used to generate Halls of Fame. In this database scenario, by Hall of Fame we refer to distinguished tuples; entities, whose characteristics set them apart from the majority. We define every Hall of Fame as one specific instance of an SQL query, such that a change in its result is considered a noteworthy event. Identified changes (i.e., events) are ranked using lexicographic tradeoffs over event and query properties and presented to users or fed in higher-level applications. We have implemented a full-fledged prototype system that uses either database triggers or a Java based middleware for event identification. We report on an experimental evaluation using a real-world dataset of basketball statistics.
Sestrin2 Modulates AMPK Subunit Expression and Its Response to Ionizing Radiation in Breast Cancer Cells
Toran Sanli, Katja Linher-Melville, Theodoros Tsakiridis, Gurmit Singh
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0032035
Abstract: Background The sestrin family of stress-responsive genes (SESN1-3) are suggested to be involved in regulation of metabolism and aging through modulation of the AMPK-mTOR pathway. AMP-activated protein kinase (AMPK) is an effector of the tumour suppressor LKB1, which regulates energy homeostasis, cell polarity, and the cell cycle. SESN1/2 can interact directly with AMPK in response to stress to maintain genomic integrity and suppress tumorigenesis. Ionizing radiation (IR), a widely used cancer therapy, is known to increase sestrin expression, and acutely activate AMPK. However, the regulation of AMPK expression by sestrins in response to IR has not been studied in depth. Methods and Findings Through immunoprecipitation we observed that SESN2 directly interacted with the AMPKα1β1γ1 trimer and its upstream regulator LKB1 in MCF7 breast cancer cells. SESN2 overexpression was achieved using a Flag-tagged SESN2 expression vector or a stably-integrated tetracycline-inducible system, which also increased AMPKα1 and AMPKβ1 subunit phosphorylation, and co-localized with phosphorylated AMPKα-Thr127 in the cytoplasm. Furthermore, enhanced SESN2 expression increased protein levels of LKB1 and AMPKα1β1γ1, as well as mRNA levels of LKB1, AMPKα1, and AMPKβ1. Treatment of MCF7 cells with IR elevated AMPK expression and activity, but this effect was attenuated in the presence of SESN2 siRNA. In addition, elevated SESN2 inhibited IR-induced mTOR signalling and sensitized MCF7 cells to IR through an AMPK-dependent mechanism. Conclusions Our results suggest that in breast cancer cells SESN2 is associated with AMPK, it is involved in regulation of basal and IR-induced expression and activation of this enzyme, and it mediates sensitization of cancer cells to IR.
Difficult airway and difficult intubation in postintubation tracheal stenosis: a case report and literature review
Zarogoulidis P,Kontakiotis T,Tsakiridis K,Karanikas M
Therapeutics and Clinical Risk Management , 2012,
Abstract: Paul Zarogoulidis,1 Theodoros Kontakiotis,1 Kosmas Tsakiridis,2 Michael Karanikas,3 Christos Simoglou,4 Konstantinos Porpodis,1 Alexandros Mitrakas,3 Agisilaos Esebidis, 3 Maria Konoglou,5 Nikolaos Katsikogiannis,6 Vasilis Zervas,1 Christina Aggelopoulou,7 Dimitrios Mikroulis,4 Konstantinos Zarogoulidis11Pulmonary Department, "G Papanikolaou" General Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece; 2Cardiothoracic Department, Saint Luke Private Hospital, Thessaloniki, Greece; 31st University Surgery Department, 4Cardiothoracic Department, University General Hospital of Alexandroupolis, Democritus University of Thrace, Alexandroupolis, Greece; 51st Pulmonary Department, "G Papanikolaou" General Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece; 6Surgery Department (NHS), 7Neurology Department (NHS), University General Hospital of Alexandroupolis, Democritus University of Thrace, Alexandroupolis, GreeceAbstract: Management of a "difficult airway" remains one of the most relevant and challenging tasks for anesthesiologists and pulmonary physicians. Several conditions, such as inflammation, trauma, tumor, and immunologic and metabolic diseases, are considered responsible for the difficult intubation of a critically ill patient. In this case report we present the case of a 46-year-old male with postintubation tracheal stenosis. We will focus on the method of intubation used, since the patient had a "difficult airway" and had to be intubated immediately because he was in a life-threatening situation. Although technology is of utter importance, clinical examination and history-taking remain invaluable for the appropriate evaluation of the critically ill patient in everyday medical life. Every physician who will be required to perform intubation has to be familiar with the evaluation of the difficult airway and, in the event of the unanticipated difficult airway, to be able to use a wide variety of tools and techniques to avoid complications and fatality.Keywords: difficult airway, bronchoscopic intubation, predictive factors, predictive scales
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