Operational Operational Indicators Operational KPIs Operational Planning Operational Procedures Operational Program "Macedonia-Thrace 2007-2013" Operational Programmes Operational Programs Operational Risk Operational Risk Management Operational excellence Operational integration of urban spaces Operations Operations Management Operator Operator E^2 and E^4 Ophthalmic Institute Opinion Mining Opinions Configuration Factors Opinions of teachers Opportunism Opportunities Opportunities & Threats Opportunity Opthalmology Optical Resonators Optical Gain Cross-section Optical Communication Optical Illusion Museum Optical Simulations Optical coherence tomography Optics Optimal Path Optimal Strategy Optimal path Optimal portfolio Optimization Optimization Algorithm Optimization Algorithms Optimization algorithm Optimization of customs roles Optimization, production planning, detergents, bottling, efficiency Optimizer Optimum Currency Area Theories Optimum Currency Areas Optimum Currency Areas (OCA) Options Optogenetic modification of memory, memory circuits, memory overview, Optogenetic memory manipulation, transBit Oracle APEX Oracle Forms Oracle RDBMS Oracles (Χρησμοί) Oracy skills Oracy skills, puppet / mascot, kindergarten learners, vocabulary acquisition/retention Oracy skills/ Ακουστικές και προφορικές δεξιότητες Oral Health Literacy Profile Oral Health Related Quality of Life Oral History Oral history Oral performance Προφορική επίδοση Oral skills Προφορικές δεξιότητες Oral speech Orange Orchestra communication Orchestra economics Orchestras in crisis Order Slicing algorithm, FPGA, SoC, VHDL. Order statistics Ordered Weighted Averaging (OWA) Orders Ordinal Logistic Regression Ordinary Differential Equations (ODEs), Partial Differential Equations (PDEs), Machine Learning, Neural Networks, Neural Network Architectures, Activation functions, DeepXDE, PINNs, Computational cost, Accuracy, Overfitting Orestiada Orestiada’s Panhellenic Festival of Amateur Theater Organic Organic Food Products Organic Photovoltaics, Polymer Solar Cells, ΟPV, PSCs, Third Generation Photovoltaics, New Technologies, Print Technology, Organic Photovoltaic Roll-to-Roll Printing Organic diodes Organic farming and foods Organic fertilizer Organic honey Organic photovoltaics Organic products, health awareness, environmental concern, eco-labels, price, intention to purchase. Organic transistors Organic waste Organic waste water charge Organisational Commitment Organisational changes Organisational creativity Organisational culture, leadership, evaluation, managerial role, teachers Organisational culture, learning organization, effectiveness, school climate, tranformative / participatory leadership, obstacles- difficulties. Organisational resilience Organisation’s structure Evaluation Organised Fan Club Community Organised play Organization Organization Change Organization Chart Organization and Operation of the School Unit Organization chart Organization for Economic Co-Operation and Development (OECD) Organization of Joint Actions (synergy) Organization of museum’s exhibitions, technology and civilization, museums in digital season, digital exhibition, digital civilization, interdisciplinary cooperation, augmented and virtual reality (AR, VR), interactive exhibits, digital conservation, 3D, digital chimera   Organization-Operation of a classroom. Organizationa greening Organizational Adaptation Organizational Behavior Organizational Chart Organizational Citizenship Behavior Organizational Commitment Organizational Commitment, Job Satisfaction, Organizational Behavior Organizational Conflict Organizational Culture Organizational Culture Assessment Instrument (OCAI) Organizational Culture, Innovation Management, Technical Sector, Greece Organizational Culture, Public Hospital, Competitive Value Framework, OCAI tool Organizational Development Organizational Goals Organizational Interest Organizational Justice Organizational Learning Organizational Learning Culture Organizational Paradigms Organizational Performance Organizational Structure Organizational Structure,(de)centralization Organizational Success Organizational Support Organizational Supportiveness Organizational Trust Organizational behavior Organizational change Organizational change/culture Organizational citizenship behavior Organizational climate Organizational commitment Organizational crisis communication and management, Organizational culture Organizational culture, Competing Values Framework, OCAI method Organizational performance Organizational support Organizations Organizations against drugs Organizations’ performance Organized Crime Organized Crime Perpetrator Organized Trip Organized crime Organized crime, criminal network, criminal organization, state-organized crime, Greek crisis Organized tourism Organized travel contract Organizing Orientalism Orientalism και Οριενταλισμός Orientalist perspectives/stereotypes Orienteering Problem Origin Origin Καταγωγή Original Original Sin Original drugs Originality Originals Orlan Oropharyngeal dysphagia Orrganizational commitment Orson Welles Orthodox Orthodox Bishop Orthodox Church Orthodox Church of Greece Orthodox Diaspora Orthodox Pastoral Care Orthodox iconism Orthodox liturgical types Orthodox theology Orthodox tourism Orthodoxy Orthogonal curvilinear coordinate system Orthopaedic Surgery Orwell Osama Alomar Oscillations Oskar Schlemmer Osmotic computing Osteoporosis Osteoporosis, old age, men, diet, exercise. Osteoporosis. Ostomy Products Ostrom Ostrom' s design principles Othello Othello Game Other Otherness Others’ Emotion Appraisal Ottoman Library Out of Court Workout (OCW) Out of Order execution Out-of-court Compromises Outbound Marketing Outcomes Outdoor Outdoor Language Learning Outdoor Play Outdoor activities Outdoor lighting Outdoor sightseeing Outil numérique Outils numériques Outils éducatifs Outlier Detection Outliers Outpouring Output Power of Laser Output Pulse Outsourcing Outsourcing Readiness Outsourcing Readiness Framework & Model Outsourcing Transition Outsourcing human resources management, strategic goals, collaboration, competitive advantage Over the top streaming platform, forecasting techniques, predict with accuracy Over-credited households (borrowers) OverActive Bladder, Urinary incontinence, Quality of life, Urgency. Overall Health Overall Job Satisfaction, Job Satisfaction per Facet, Medical-Nursing Personnel, Secondary-Level Hospital, Spector’s JSS Questionnaire. Overall Tourism Product, Local Authorities, Thessaloniki Overall Tourist Product of Epirus Region Overall capital efficiency Overqualification Overround Overtourism Owner and contractor of the project Ownership Models Oxidation Ozone Oδηγική συμπεριφορά Oικονομική Κρίση Oικονομική κρίση Oικονομική κρίση, Oικονομικές Kαταστάσεις Oικοσύστημα νεοφυών επιχειρήσεων Oινοτουρισμός Oινοτουρισμός, Κεντρική Ελλάδα, Κύκλος Ζωής, Κύκλος Ζωής οινοτουριστικών προορισμών, οίνος Oκτόνια Oλιγοθέσιο σχολείο Oλική ποιότητα, ανακύκλωση, διαχείριση απορριμμάτων, βιώσιμη, πράσινη Oμάδα React Oμαδική συνθετική εργασία Oντολογία, έκφραση, αισθητική, ιδιότητες, τέχνη. Oπαδικές κοινότητες, οπαδική ταυτότητα, βαθμός ταυτοποίησης, οπαδική κουλτούρα Oπαδικές κοινότητες, οπαδική ταυτότητα, τοπική ταυτότητα, κοινότητες οπαδών Oπτική ταυτότητα Oπτικοποίηση δεδομένων Oπτικός γραμματισμός Oργάνωση Eκδηλώσεων Oργάνωση και διοίκηση Oργανισμοί Oργανωμένο έγκλημα, οικονομική κρίση, πανδημία, ποινική καταστολή. Oργανωσιακή Δικαιοσύνη Oργανωσιακή υποστήριξη Oργανωτική Απόδοση Oργανωτική δέσμευση P / BV P / E P / Sales P-graphs P. Freire P. Jarvis P.A.Y.T. P.E.R.T. P.I.O.P. P.O.S. P.P.P's P.V.T.I. P2G Technology P2P Lab P2P lending, crowdfunding, financial system, banking, investments PA 2014-2020 PACIC-PLUS PACKAGING MATERIALS PACT-Q2 PADLET PAF Method PAIN MANAGEMENT PANAS PANCHATANTRA PANDA BONDS PANDEMIC PANDEMIC COVID 19 PANDEMIC COVID-19 PANDEMIC IMPACT PANDEMIC-ΠΑΝΔΗΜΙΑ PANEL DATA PAPANIKOLOU LANDFILL PAPER MILL INDUSTRY PARENTAL INVOLVEMENT PARENTAL ROLE PARENTS PARENTS' SCHOOLS