The Albanian Migration to Greece and the Refugee Crisis of 2015 from the Greek Perspective

Although migration has always been a timeless and volatile phenomenon, modern transnational movements of people have become a dominant topic of interest by constantly acquiring new characteristics that modify their evolutionary process. Europe is a geographical area that has been significantly affected by recent changes as a result of the evolution of migration flows of the last 30 years. The urgent need to initially understand and later implement evidence-based policies in order to sufficiently manage the migration phenomenon can be considered as the basic spark that led to the scientific blast of the 21st century, focusing on the gradual development of migration studies. One of the most notable efforts of the scientific community was the use of the comparison method to examine, understand, and in some cases even forecast the characteristics of specific migration case studies, thereby forming the backbone of comparative migration research in general. Greece, due to its geographical position, has been unintentionally positioned, many times, inside the so called "ring of fire", as result of multiple factors and disastrous events that evolved mainly in its neighbouring countries, forcing massive, irregular migration flows to its external borders. The outbreak of the Albanian exodus in the early 1990s and the recent refugee flows of 2015 can be described as two major migration crises that have occurred in Greek’s contemporary history, making their comparison a fruitful example of the potential capabilities of the above-mentioned method, contributing to a holistic study of the migration phenomenon in Greece

Influence of combined thermal and mechanical loadings on pearlitic steel microstructure in railway wheels and rails

One of the most important aspects in railway operation is the interaction between rail and wheel. The contact patch between these two components is around the size of a small coin, and since high loads act on this small area, stresses will give rise to wear and damage in both components. Frictional forces on the surface of wheels and rails caused by recurring train acceleration, braking, curving and occasional slippage can cause cyclic plastic deformation and heating, which in turn causes an aligned, anisotropic microstructure with altered mechanical behaviour. Control of material property degradation is an important topic for guiding maintenance, as well as ensuring safety of railways, since it will allow for a more accurate prediction of material wear and lifetime.The thesis focuses on the mechanical properties of railway wheel and rail steels after exposure to elevated temperatures and plastic deformation. Specifically examined are the carbon wheel steels, UIC ER7T and ER8T (~0.55 wt. %C) and rail steel R260 (~0.72 wt. %C). During their service life, the surface layers of rails and wheels are subjected to very high rolling contact loads. These lead to accumulation of large shear strains close to the running surface. Moreover the high thermal loads that wheels experience when block brakes are used can cause severe degradation of the material microstructure, more specifically spheroidisation of the pearlite, which combined with plastic deformation (that makes the material more prone to spheroidisation) can lead to severe deterioration of the material’s mechanical properties. Both un-deformed and pre-strained wheel materials were heat treated at various temperatures from 250\ub0C to 600\ub0C for various durations, and the change in room temperature hardness was analysed. Additionally, Electron Backscatter Diffraction Analysis (EBSD) was used to evaluate if orientation gradients in the pearlitic colonies affect the spheroidisation of the pearlitic microstructure, that is observed at higher temperatures. Uniaxial (tension-compression) and biaxial (including torsion) low cycle fatigue tests were performed to study the behaviour of R7T and R8T material at different temperatures. The influence of hold times as well as the ratchetting behaviour with mean stress effects were also studied. Virgin rail material was twisted using a biaxial machine to various shear strain levels to create a microstructure representative for the surface layer observed in field samples. The microstructure was characterised using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and hardness measurements.The results showed that wheel material hardening due to strain ageing takes place at around 300\ub0C while microstructural degradation caused softening at higher temperatures. Spheroidisation of the pearlite started to become visible at 450\ub0C for the un-deformed material and at around 400\ub0C for the pre-strained. The spheroidised areas appear to have lost their initial orientation gradients after spheroidisation and obtain a more uniform orientation. Cyclic tests at elevated temperature revealed cyclic hardening at around 300\ub0C, as an effect of dynamic strain ageing. At higher temperatures, cyclic softening followed due to a combination of increasing thermal activation and spheroidisation. Biaxial testing showed a more severe effect of strain hardening and shorter fatigue life. For the rail material, the dislocation density was found to increase with increasing shear strain. The flow stresses calculated using microstructural parameters such as dislocation density and interlamellar spacing of the pearlite seem to agree well with those evaluated from hardness measurements

A severe coarctation of aorta in a 72-year-old female: a case report

Aortic coarctation is a congenital malformation of the aorta usually diagnosed and corrected early in life. Long-term survival is exceptional in patients with untreated aortic coarctation. In this case report, we present a late diagnosis of aortic coarctation in a 72-year-old female. Our patient was relatively asymptomatic until she presented with exertional dyspnea and fatigue in her seventh decade of life. The patient was managed conservatively with aggressive antihypertensive medication. After the 1-year follow-up visit, the patient was in good clinical condition, without, however, adequate control of blood pressure

The COVID-19 Pandemic and Its Effects on the Greek Tourism Sector: A Case Study of the Region of Eastern Macedonia - Thrace

The recent novel coronavirus pandemic (COVID-19 pandemic) has led to a new, multi-faceted societal, healthcare and generalized economic crisis, both at national and international levels. The measures taken to deal with the pandemic have resulted in unprecedented situations in almost all sectors of the Greek economy. This article attempted to investigate the extent of the impact of this new crisis on Greek tourism companies, focusing on the case of tourist accommodation and food services by region, since the tourism industry has been greatly afflicted. The main variable examined was the degree of decline in the turnover of the tourism businesses under discussion over the last two years, at regional and national levels. This was supplemented with comparative analyses of similar measurable data. Secondary and statistical data were obtained from the Hellenic Statistical Authority, the Hellenic Tourism Organization and databases of other related institutions. Keywords: COVID-19, tourism industry, Greek companies, tourist product, region οf Eastern Macedonia - Thrac

Modelling of temperature and strain rate dependent behaviour of pearlitic steel in block braked railway wheels

Block braked railway wheels are subjected to thermal and rolling contact loading. The thermal loading results in high temperatures and thermal stresses which cause slow time dependent processes such as creep, relaxation and static recovery of the wheel material. At the same time, the rolling contact loading implies a very fast mechanical load application. This paper is focused on material modeling of pearlitic steel for a wide range of loading rates at elevated temperatures. The starting point is a viscoplasticity model including nonlinear isotropic and kinematic hardening. The Delobelle overstress function is employed to capture strain rate dependent response of the material. The model also includes static recovery of the hardening to capture slower viscous (diffusion dominated) behaviour of the material. Experiments for the pearlitic wheel steel ER7 in terms of cyclic strain-controlled uniaxial tests with hold-time, uniaxial ratchetting tests including rapid cycles and biaxial cyclic tests with tension/compression and torsion are used to calibrate the material model. These experiments were performed under isothermal conditions at different temperatures. In the ratchetting tests, higher loading rates are obtained and these have been used to calibrate the high strain rate response of the viscoplasticity model. The paper is concluded with a numerical example of a block braked wheel where the importance of accounting for the viscoplasticity in modelling is highlighted

Primary Ewing sarcoma of the axis-C2: A case report and the review of the literature

Introduction Neck pain and torticollis are common symptoms in the pediatric population that rarely requires further investigation. However, in case symptoms persist, then a more meticulously approach should be considered. Underlying conditions such as infections, neck injury, autoimmune disorders or even cervical spine cancer should be excluded from diagnosis. Cervical spine cancer is a rare neurosurgical entity in the pediatric population and even rarer is atlantoaxial Ewing's sarcoma. In this report, we present a rare case of primary Ewing's sarcoma of the axis. Case report A 3.5-year-old female with progressive neck pain and intermittent episodes of torticollis was referred to our outpatient clinic. Imaging studies revealed a malignant tumor located on C2 vertebra. Diagnosis of Ewing's Sarcoma was confirmed via open biopsy and the patient was treated with Euro-EWING 99 chemotherapy. Conclusion Pediatric neck pain and/or torticollis should raise high suspicion for malignancy of cervical spine. Modern diagnostic means and techniques can assist in the screening and diagnosis of these tumors

Burnout and motivation to study medicine among students during the COVID-19 pandemic

AimTo investigate medical students’ burnout and motivation levels in each of the six years of their studies during the COVID-19 pandemic and identify independent predictors of burnout and motivation.MethodsAn anonymous cross-sectional survey was sent to the students of all six years within our school. Burnout was measured with the adapted Oldenburg Burnout Inventory questionnaire (OLBI-S) and motivation with the updated Strength of Motivation for Medical School (SMMS-R) questionnaire. Univariate analysis was performed with the Kruskal–Wallis test and Spearman’s correlation, while multivariable analysis with linear regression models.ResultsA total of 333 medical students (52% of student body) responded. Higher burnout levels correlated with lower motivation to study medicine (rho = −0.30, p < 0.001). Burnout levels differed between the six years of medical studies, peaking in years two and four whereas being the lowest in year one (p = 0.01). Motivation levels differed significantly as well, peaking in years one and four whereas being the lowest in years five and six (p = 0.012). In the multivariable linear regression models, being a female (b = 2.22, p = 0.016), studying in the fourth year vs. first year (b = 2.54, p = 0.049), having a perceived beginner/intermediate vs. advanced/expert technology level (b = 2.05, p = 0.032) and a perceived poor school support system (b = 6.35, p < 0.001) were independently associated with higher burnout levels. Furthermore, studying in the fifth year vs. first year (b = −5.17, p = 0.019) and a perceived poor school support system (b = −3.09, p = 0.01) were independently associated with a reduced motivation to study medicine.ConclusionOur study highlighted potential areas for intervention to decrease the rate of burnout and low motivation among medical students. However, further research is needed to unravel the full effect of the pandemic on medical students

Patients with Atrial Fibrillation and Chronic Kidney Disease More Often Undergo Angioplasty of Left Main Coronary Artery – a 867 Patient Study

Background/Aims: Several studies have implicated atrial fibrillation (AF) as a contributing factor in chronic kidney disease (CKD) and cardiovascular events. The prevalence of coronary artery disease (CAD) in patients with AF varies substantially from 17% to 46.5%. There are only few studies concerning renal function in population with AF undergoing coronary angiography. The aim of the present study was to assess which type of AF is dominant in CKD population scheduled for coronary angiography and if it can influence patients’ outcome, the association between renal impairment and the type of coronary procedures in AF patients and the influence of renal function on in-hospital mortality. Methods: We retrospectively studied 867 patients with AF hospitalized due to coronary angiography in two year time. The cut off value of CKD was eGFR ≤ 60 ml/min./1.73m2 evaluated by CKD-EPI formula. Results: A total of 867 patients with AF (44% women; mean age 72±10 years) were included in the analysis. The mean eGFR was 44±11ml/min./1.73m2 in patients with CKD and 89±18 ml/min./1.73m2 in patients with preserved renal function. Patients with CKD and AF were older (p< 0.001), had more often diabetes (p=0.009), heart failure (p< 0.001) and anaemia (p< 0.001). Patients with CKD and AF had more often permanent type of AF (p< 0.001). In CKD patients CHA2DS2VASc score was 4.3±1.5 and HAS-BLED score was 2.0±1.2 and it was significantly higher as compared to population with preserved renal function (p< 0.001, p=0.02, respectively). The use of oral anticoagulation was less frequent in CKD group (p< 0.001) although these patients had higher CHA2DS2VASc score. Patients with AF and CKD were more often admitted due to myocardial infarction (STEMI or NSTEMI) (p=0.02, p< 0.001, respectively) and more often underwent percutaneous coronary intervention (PCI) (p=0.01). Among coronary arteries the percutaneous coronary intervention (PCI) of left main artery was done more frequently in CKD patients (p=0.01). Among CKD population in-hospital mortality was significantly higher in patients with eGFR < 30 ml/min (p< 0.001). Conclusion: Patients with CKD had more often permanent type of AF. Percutaneous interventions of the left main coronary artery, the only elective procedures influencing patients’ prognosis, were done more frequently in CKD patients with AF. In-hospital mortality was significantly higher in patients with severe renal impairment. Despite the higher risk of ischaemic stroke in CKD group the use of oral anticoagulation therapy was significantly less frequent and the patients were deprived of the confirmed benefits of such treatment

Impact on outcome of different types of carotid stent: Results from the European Registry of Carotid Artery Stenting

AIMS: Conflicting data exist on the impact on outcome of the use of different stent types during carotid artery stenting (CAS). The aim of this study was to evaluate clinical outcomes according to different carotid stent design among the population of the European Registry of Carotid Artery Stenting (ERCAS). METHODS AND RESULTS: The present study was conducted in 1,604 patients who underwent neuroprotected CAS in ERCAS. All types of commercially available carotid stent were used. Open-cell design stents were classified according to free cell area into 7.5 mm2. A total of 713 closed-cell, 456 hybrid-cell, 238 7.5 mm2 open-cell stents were implanted. Overall, the 30-day stroke and death rate was 1.37%. At 30 days, 19 strokes occurred (1.18%): eight in the group of patients treated with a closed-cell (1.12%), two in those with a hybrid-cell (0.44%), three in those with a 7.5 mm2 open-cell stent (3.05%) (p=0.045). CONCLUSIONS: Data of the present study suggest that, in the setting of neuroprotected CAS performed in high-volume centres by properly trained operators, the use of an open-cell design stent with a free cell area >7.5 mm2 may be associated with an increased 30-day stroke risk