Spatial Event Detection in Twitter: A Comparison of State-of-the-Art Techniques

Κατά την διάρκεια της τελευταίας δεκαετίας, οι πλατφόρμες κοινωνικής δικτύωσης όπως το Twitter έχουν αναπτυχθεί και ωριμάσει, με αποτέλεσμα τεράστιο πλήθος δεδομένων να δημιουργείται σε πραγματικό χρόνο. Οι χρήστες αυτών των δικτύων, μεταφορτώνουν συνεχώς δεδομένα σχετικά με την κατάσταση του περιβάλλον τους. Αυτή η πλούσια συλλογή δεδομένων μπορεί να χρησιμοποιηθεί για να προσφέρει ανάδραση πραγματικού χρόνου για ενεργά γεγονότα, η οποία μπορεί να αξιοποιηθεί με ποικίλους τρόπους. Σε αυτήν την πτυχιακή εργασία, δοκιμάζουμε δύο συστήματα, ανίχνευσης γεγονότων στοχευμένου τομέα, ένα εκ των οποίων είναι με επίβλεψη, και το άλλο είναι χωρίς. Αυτά τα συστήματα ανίχνευσης γεγονότων, επεξεργάζονται μια συλλογή από χρονικά ταξινομημένα δεδομένα και εκτελούν την διαδικασία της ανίχνευσης γεγονότων ως μια σωλήνωση τριών διακριτών βημάτων, αυτό του φιλτραρίσματος, της χωρικής συσταδοποίησης και της βαθμολόγησης. Στο βήμα του φιλτραρίσματος, τα tweets, έπειτα από επεξεργασία, χωρίζονται σε δύο κατηγορίες, αυτά που είναι συναφή με τον τομέα, και αυτά που δεν είναι. Το επόμενο βήμα της διαδικασίας είναι η χωρική συσταδοποίηση των συναφών tweets σε συναφής περιοχές. Στο τελικό στάδιο της διαδικασίας, οι περιοχές οι οποίες είχαν εξορυχθεί κατά την διαδικασία της χωρικής συσταδοποίησης, ταξινομούνται με τέτοιο τρόπο, ώστε οι περιοχές οι οποίες είχαν επηρεαστεί περισσότερο από το γεγονός, να βαθμολογούνται υψηλότερα. Πιο συγκεκριμένα, το σύστημα με επίβλεψη, απαιτεί ανθρώπινη εργασία και έναν απλό αλγόριθμο για το φιλτράρισμα των tweets. Σε αντίθεση, το σύστημα χωρίς επίβλεψη υιοθετεί έναν αλγόριθμο χωρίς επίβλεψη για αυτήν την διαδικασία. Και τα δύο συστήματα συσταδοποιούν τα συναφή tweets, είτε με τον αλγόριθμο k-Means, είτε με έναν αλγόριθμο συσταδοποίησης γράφων με την χρήση της μετρικής modularity. Τέλος, αυτά τα συστήματα ταξινομούν τις συστάδες με βάση κάποιες στρατηγικές βαθμολόγησης. Κατά την διάρκεια των πειραμάτων μας, κατέστη σαφές πως το σύστημα χωρίς επίβλεψη, είχε χειρότερα αποτελέσματα από το σύστημα με επίβλεψη, αλλά δεν απαιτεί χρόνο για τον χαρακτηρισμό των δεδομένων, και με αυτόν τον τρόπο προσφέρει έναν καλό συμβιβασμό μεταξύ ανθρώπινης εργασίας και ακρίβειας των αποτελεσμάτων.During the last decade, social media platforms such as Twitter have grown and matured to a point where enormous amounts of data are being generated in real-time fashion. Users of these networks are constantly uploading information about the current state of their surroundings. This wealth of information can be exploited in order to provide meaningful real-time feedback about ongoing events for a wide range of applications. In this thesis, we test two targeted domain, event detection systems; one that is supervised and one that is not. These event detection systems, process a collection of time-indexed data and perform the detection procedure as a pipeline of three discrete steps, a filtering phase, a spatial clustering phase, and a scoring phase. In the filtering phase, the tweets get processed, and they are divided into two categories, those that are related to the targeted domain and those that are not. The next step of the process is the spatial clustering, which aggregates the related tweets into areas of interest. As the last part of the process, the regions that were extracted by the clustering phase, are sorted, by ranking higher those regions that were mostly affected by the event. More specifically, the supervised system, requires human labor and a simple algorithm for filtering the tweets. By contrast, the unsupervised system employs an unsupervised algorithm for this process. Both systems cluster the related tweets, either with the k-Means algorithm, or with a modularity based graph clustering algorithm. Finally these systems rank the resulting clusters with the help of several ranking schemes. During our experiments, it became clear that the unsupervised system provides worse results than the supervised approach, but it does not require time for labeling the data, and thus it provides a good trade-off between human labor and accuracy of the results

Acute seizures in acute ischemic stroke: does thrombolysis have a role to play?

Seizures appear at stroke presentation, during the acute phase or as a late complication of stroke. Thrombolysis has not been investigated as a risk factor despite its potential neurotoxic effect. We try to identify risk factors for seizures during the acute phase of ischemic stroke in a cohort including thrombolysed patients. We undertook a case-control study at a single stroke center using data from Acute Stroke Registry and Analyse of Lausanne (ASTRAL). Patients with seizure occurring during the first 7days following stroke were retrospectively identified. Bi-variable and multivariable statistical analyses were applied to compare cases and randomly selected controls. We identified 28 patients experiencing from seizures in 2,327 acute ischemic strokes (1.2%). All seizures occurred during the first 72h. Cortical involvement, thrombolysis with rt-PA, arterial recanalization, and higher initial NIHSS were statistically associated with seizures in univariated analysis. Backward linear regression identified cortical involvement (OR 7.53, 95% CI 1.6-35.2, p<0.01) and thrombolysis (OR 4.6, 95% CI 1.6-13.4, p=0.01) as being independently associated with seizure occurrence. Overall, 3-month outcome measured by the modified Rankin scale (mRS) was comparable in both groups. In the subgroup of thrombolysed patients, outcome was significantly worse at 3months in the seizure group with 9/12 (75%) patients with mRS ≥3, compared to 6/18 (33.3%) in the seizure-free group (p=0.03). Acute seizures in acute ischemic stroke were relatively infrequent. Cortical involvement and thrombolysis with rt-PA are the principal risk factors. Seizures have a potential negative influence on clinical outcome in thrombolysed patient

THE PSYCHOLOGICAL AND SOCIO-ECONOMIC IMPACTS OF FESTIVAL CELEBRATIONS ON THE ISLAND OF RHODES, GREECE, DURING THE COVID-19 PANDEMIC

This research paper aims to study the function of the traditional festivals on the island of Rhodes during the period of the COVID-19 pandemic in order to explore community members and official institution representatives’ views on their psychological and socio-economic consequences. A structured interview was designed, which was given online to 168 subjects, of which 96 community members in the villages of the island of Rhodes and to 72 official institutions, representatives of cultural and local authorities, within the context of the beginning of the festivities with some restrictions, in August 2021, in the light of the pandemic. The results of the research show that the majority of community members and official institution representatives of the sample emphasize the communicative, cultural, recreational, and social dimensions of the festivals, however, some claim that there are no longer events that arise interest. Regarding their cancellation during the pandemic period, the majority of community members answer that the entertainment - communication sector was most affected, while the representatives of the institutions emphasize the economic consequences. In general, regarding the consequences of the pandemic on the behavior and psychology of individuals, introversion, isolation, antisociality, belligerence, tension and nervousness, are emphasized, while mistrust seems to prevail even in close family settings. Moreover, the majority of community members and representatives emphasize that social offer and solidarity are not exhibited to a satisfactory degree, while volunteering activities are limited. Regarding the pandemic, vaccination is suggested as the most effective means, mainly by the official institution representatives. Regarding the events of 2021 that shocked them most, the community members focus on economic, social and psychological - personal problems, while the official institution representatives focus on environmental and economic problems. Finally, most of them state that they do not want the transformation of festivals, however, they regard the emphasis on tradition as a sustainable perspective of local festivals.  Article visualizations

Effects of antiplatelet therapy on stroke risk by brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases: subgroup analyses of the RESTART randomised, open-label trial

Background Findings from the RESTART trial suggest that starting antiplatelet therapy might reduce the risk of recurrent symptomatic intracerebral haemorrhage compared with avoiding antiplatelet therapy. Brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases (such as cerebral microbleeds) are associated with greater risks of recurrent intracerebral haemorrhage. We did subgroup analyses of the RESTART trial to explore whether these brain imaging features modify the effects of antiplatelet therapy

Effects of antiplatelet therapy after stroke due to intracerebral haemorrhage (RESTART): a randomised, open-label trial

Background: Antiplatelet therapy reduces the risk of major vascular events for people with occlusive vascular disease, although it might increase the risk of intracranial haemorrhage. Patients surviving the commonest subtype of intracranial haemorrhage, intracerebral haemorrhage, are at risk of both haemorrhagic and occlusive vascular events, but whether antiplatelet therapy can be used safely is unclear. We aimed to estimate the relative and absolute effects of antiplatelet therapy on recurrent intracerebral haemorrhage and whether this risk might exceed any reduction of occlusive vascular events. Methods: The REstart or STop Antithrombotics Randomised Trial (RESTART) was a prospective, randomised, open-label, blinded endpoint, parallel-group trial at 122 hospitals in the UK. We recruited adults (≥18 years) who were taking antithrombotic (antiplatelet or anticoagulant) therapy for the prevention of occlusive vascular disease when they developed intracerebral haemorrhage, discontinued antithrombotic therapy, and survived for 24 h. Computerised randomisation incorporating minimisation allocated participants (1:1) to start or avoid antiplatelet therapy. We followed participants for the primary outcome (recurrent symptomatic intracerebral haemorrhage) for up to 5 years. We analysed data from all randomised participants using Cox proportional hazards regression, adjusted for minimisation covariates. This trial is registered with ISRCTN (number ISRCTN71907627). Findings: Between May 22, 2013, and May 31, 2018, 537 participants were recruited a median of 76 days (IQR 29–146) after intracerebral haemorrhage onset: 268 were assigned to start and 269 (one withdrew) to avoid antiplatelet therapy. Participants were followed for a median of 2·0 years (IQR [1·0– 3·0]; completeness 99·3%). 12 (4%) of 268 participants allocated to antiplatelet therapy had recurrence of intracerebral haemorrhage compared with 23 (9%) of 268 participants allocated to avoid antiplatelet therapy (adjusted hazard ratio 0·51 [95% CI 0·25–1·03]; p=0·060). 18 (7%) participants allocated to antiplatelet therapy experienced major haemorrhagic events compared with 25 (9%) participants allocated to avoid antiplatelet therapy (0·71 [0·39–1·30]; p=0·27), and 39 [15%] participants allocated to antiplatelet therapy had major occlusive vascular events compared with 38 [14%] allocated to avoid antiplatelet therapy (1·02 [0·65–1·60]; p=0·92). Interpretation: These results exclude all but a very modest increase in the risk of recurrent intracerebral haemorrhage with antiplatelet therapy for patients on antithrombotic therapy for the prevention of occlusive vascular disease when they developed intracerebral haemorrhage. The risk of recurrent intracerebral haemorrhage is probably too small to exceed the established benefits of antiplatelet therapy for secondary prevention

Effects of antiplatelet therapy after stroke due to intracerebral haemorrhage (RESTART): a randomised, open-label trial

Background: Antiplatelet therapy reduces the risk of major vascular events for people with occlusive vascular disease, although it might increase the risk of intracranial haemorrhage. Patients surviving the commonest subtype of intracranial haemorrhage, intracerebral haemorrhage, are at risk of both haemorrhagic and occlusive vascular events, but whether antiplatelet therapy can be used safely is unclear. We aimed to estimate the relative and absolute effects of antiplatelet therapy on recurrent intracerebral haemorrhage and whether this risk might exceed any reduction of occlusive vascular events. Methods: The REstart or STop Antithrombotics Randomised Trial (RESTART) was a prospective, randomised, open-label, blinded endpoint, parallel-group trial at 122 hospitals in the UK. We recruited adults (≥18 years) who were taking antithrombotic (antiplatelet or anticoagulant) therapy for the prevention of occlusive vascular disease when they developed intracerebral haemorrhage, discontinued antithrombotic therapy, and survived for 24 h. Computerised randomisation incorporating minimisation allocated participants (1:1) to start or avoid antiplatelet therapy. We followed participants for the primary outcome (recurrent symptomatic intracerebral haemorrhage) for up to 5 years. We analysed data from all randomised participants using Cox proportional hazards regression, adjusted for minimisation covariates. This trial is registered with ISRCTN (number ISRCTN71907627). Findings: Between May 22, 2013, and May 31, 2018, 537 participants were recruited a median of 76 days (IQR 29–146) after intracerebral haemorrhage onset: 268 were assigned to start and 269 (one withdrew) to avoid antiplatelet therapy. Participants were followed for a median of 2·0 years (IQR [1·0– 3·0]; completeness 99·3%). 12 (4%) of 268 participants allocated to antiplatelet therapy had recurrence of intracerebral haemorrhage compared with 23 (9%) of 268 participants allocated to avoid antiplatelet therapy (adjusted hazard ratio 0·51 [95% CI 0·25–1·03]; p=0·060). 18 (7%) participants allocated to antiplatelet therapy experienced major haemorrhagic events compared with 25 (9%) participants allocated to avoid antiplatelet therapy (0·71 [0·39–1·30]; p=0·27), and 39 [15%] participants allocated to antiplatelet therapy had major occlusive vascular events compared with 38 [14%] allocated to avoid antiplatelet therapy (1·02 [0·65–1·60]; p=0·92). Interpretation: These results exclude all but a very modest increase in the risk of recurrent intracerebral haemorrhage with antiplatelet therapy for patients on antithrombotic therapy for the prevention of occlusive vascular disease when they developed intracerebral haemorrhage. The risk of recurrent intracerebral haemorrhage is probably too small to exceed the established benefits of antiplatelet therapy for secondary prevention

Effects of antiplatelet therapy after stroke due to intracerebral haemorrhage (RESTART): a randomised, open-label trial

BACKGROUND: Antiplatelet therapy reduces the risk of major vascular events for people with occlusive vascular disease, although it might increase the risk of intracranial haemorrhage. Patients surviving the commonest subtype of intracranial haemorrhage, intracerebral haemorrhage, are at risk of both haemorrhagic and occlusive vascular events, but whether antiplatelet therapy can be used safely is unclear. We aimed to estimate the relative and absolute effects of antiplatelet therapy on recurrent intracerebral haemorrhage and whether this risk might exceed any reduction of occlusive vascular events. METHODS: The REstart or STop Antithrombotics Randomised Trial (RESTART) was a prospective, randomised, open-label, blinded endpoint, parallel-group trial at 122 hospitals in the UK. We recruited adults (≥18 years) who were taking antithrombotic (antiplatelet or anticoagulant) therapy for the prevention of occlusive vascular disease when they developed intracerebral haemorrhage, discontinued antithrombotic therapy, and survived for 24 h. Computerised randomisation incorporating minimisation allocated participants (1:1) to start or avoid antiplatelet therapy. We followed participants for the primary outcome (recurrent symptomatic intracerebral haemorrhage) for up to 5 years. We analysed data from all randomised participants using Cox proportional hazards regression, adjusted for minimisation covariates. This trial is registered with ISRCTN (number ISRCTN71907627). FINDINGS: Between May 22, 2013, and May 31, 2018, 537 participants were recruited a median of 76 days (IQR 29-146) after intracerebral haemorrhage onset: 268 were assigned to start and 269 (one withdrew) to avoid antiplatelet therapy. Participants were followed for a median of 2·0 years (IQR [1·0- 3·0]; completeness 99·3%). 12 (4%) of 268 participants allocated to antiplatelet therapy had recurrence of intracerebral haemorrhage compared with 23 (9%) of 268 participants allocated to avoid antiplatelet therapy (adjusted hazard ratio 0·51 [95% CI 0·25-1·03]; p=0·060). 18 (7%) participants allocated to antiplatelet therapy experienced major haemorrhagic events compared with 25 (9%) participants allocated to avoid antiplatelet therapy (0·71 [0·39-1·30]; p=0·27), and 39 [15%] participants allocated to antiplatelet therapy had major occlusive vascular events compared with 38 [14%] allocated to avoid antiplatelet therapy (1·02 [0·65-1·60]; p=0·92). INTERPRETATION: These results exclude all but a very modest increase in the risk of recurrent intracerebral haemorrhage with antiplatelet therapy for patients on antithrombotic therapy for the prevention of occlusive vascular disease when they developed intracerebral haemorrhage. The risk of recurrent intracerebral haemorrhage is probably too small to exceed the established benefits of antiplatelet therapy for secondary prevention. FUNDING: British Heart Foundation

Investigation of the relationship between retinol-binding-protein-4 and insulin resistance in the haemodialysis population

Introduction: The Retinol Binding Protein-4 (RBP-4) is a unique, special protein-carrier of retinol (vitamin A) in blood and until recently, the only known function was the transport of retinol in various tissues. Recent studies have shown that the RBP-4 seems to be involved in the onset of chronic inflammation and the development of insulin resistance. Insulin resistance and chronic inflammation are very common in patients with chronic conditions especially in those with end-stage kidney disease (CKD) receiving dialysis. However, it is not known whether the levels of RBP-4 are elevated in end stage renal disease (ESRD) patients and whether those levels are associated with factors involved in the development of insulin resistance.Purpose: The aim of the current study was to examine the levels of RBP-4 in hemodialysis patients and to explore the possibility of the association – if any - with insulin resistance. Methodology: Participants were identified among the patients with ESRD who were under a regular Hemodialysis (HD) program in the Renal Replacement Unit of Larissa University Hospital and “healthy” adult volunteers from the region of Thessaly. Volunteers in both groups had to fulfil all the inclusion criteria of this study. After providing written informed consent they participated in a series of tests to assess the aspects related to overall health, body composition, hormonal profile, haematological and biochemical parameters, the levels of insulin resistance by Homeostasis Model Assessment index Insulin Resistance Index (HOMA-IR) and the levels of RBP-4 in the blood. The study was approved by the local Ethical Committee at the University Hospital of Larissa and the University of Thessaly.Results: 35 HD patients (HD-group 12M/13F, 53.8 ± 18.1 years) and 27 healthy participants (CON-Group, 16M/11F, 52.1 ± 13.2 years) without any known kidney diseases and normal creatinine values. Τhe results showed that HD patients have significantly elevated levels of RBP-4 compared to the control group. The level of RBP-4 was not correlated significantly with the HOMA score, but only with fasting glucose, total cholesterol, iron levels, the thyroid and parathyroid hormone levels. HOMA-IR index was positively associated with anthropometric characteristics of the HD patients.Conclusions: The level of RBP-4 found to be elevated in the HD patients, while it seems that this protein is involved in metabolic pathways of chronic inflammation. However there is no strong evidence to denote any involvement of the levels of RBP-4 in the development of insulin resistance, as those assessed by the HOMA-IR index. In conclusion, the levels of RBP-4 have the potential to become an important factor for the evaluation of the metabolic profile of the HD patients and potentially be considered a supporting prognostic tool for monitoring the health of patients with chronic kidney diseases.Εισαγωγή: Η δεσμεύουσα-τη-ρετινόλη πρωτεΐνη 4 (Retinol Binding Protein 4 - RBP-4) είναι η μοναδική, ειδική πρωτεΐνη-μεταφορέας της ρετινόλης (βιταμίνη Α) στο αίμα και ως πρόσφατα η μόνη γνωστή της λειτουργία ήταν η μεταφορά της ρετινόλης στους ιστούς. Νεότερες μελέτες έχουν δείξει ότι η RBP-4 φαίνεται να εμπλέκεται στην εμφάνιση της χρόνιας φλεγμονής καθώς και στην ανάπτυξη της αντίστασης της ινσουλίνης. Η αντίσταση στην ινσουλίνη και η χρόνια φλεγμονή είναι συνήθεις χρόνιες καταστάσεις σε ασθενείς με τελικού σταδίου νεφρική νόσο (ΧΝΝ) που υποβάλλονται σε αιμοκάθαρση. Ωστόσο, δεν είναι γνωστό κατά πόσο τα επίπεδα της RBP-4 είναι αυξημένα στους ασθενείς με ΧΝΝ τελικού σταδίου και εάν σχετίζονται με παράγοντες που εμπλέκονται στην ανάπτυξη της αντίστασης στην ινσουλίνη.Σκοπός: Ο σκοπός λοιπόν της παρούσας μελέτης ήταν να εξετάσει τα επίπεδα της RBP-4 στους αιμοκαθαιρόμενους ασθενείς και να διερευνήσει την πιθανότητα συσχέτισης των επιπέδων της με την αντίσταση στην ινσουλίνη, σε ασθενείς με χρόνια νεφρική ανεπάρκεια τελικού σταδίου υπό αιμοκάθαρση. Μεθοδολογία: Συμμετέχοντες αναζητήθηκαν μεταξύ των ασθενών με ΧΝΝ τελικού σταδίου (ομάδα HD), οι οποίοι βρίσκονταν υπό συστηματική αιμοκάθαρση στη Μονάδα Τεχνητού Νεφρού του Πανεπιστημιακού Νοσοκομείου Λάρισας και “υγιών” εθελοντών από την ευρύτερη περιοχή της Θεσσαλίας. Οι εθελοντές και των 2 ομάδων έπρεπε να πληρούν όλα τα κριτήρια εισαγωγής στη μελέτη. Μετά την έγγραφη συγκατάθεσή τους συμμετείχαν σε μια σειρά από δοκιμασίες και εξετάσεις για την αξιολόγηση της κλινικής τους εικόνας, σωματικής σύστασης, ορμονικού προφίλ, αιματολογικών και βιοχημικών παραμέτρων, των επιπέδων αντίστασης στην ινσουλίνη με τον δείκτη Homeostasis Model Assessment Insulin Resistance Index (HOMA-IR) και των επιπέδων της RBP-4 πρωτεΐνης. Η μελέτη είχε έγκριση από την Επιτροπή Βιοηθικής και Δεοντολογίας του Πανεπιστημιακού Νοσοκομείου Λάρισας και από την Ιατρική Σχολή του Πανεπιστημίου Θεσσαλίας. Αποτελέσματα: Στην παρούσα μελέτη συμμετείχαν 35 ασθενείς με ΧΝΝ τελικού σταδίου (ομάδα HD, 12Α/13Θ, 53,8±18,1 έτη) και 27 υγιείς συμμετέχοντες (ομάδα CON, 16Α/11Θ, 52,1±13,2 έτη) με φυσιολογικές τιμές κρεατινίνης. Τα αποτελέσματα έδειξαν ότι οι αιμοκαθαιρόμενοι ασθενείς έχουν σημαντικά αυξημένα τα επίπεδα της RBP-4 σε σχέση με την ομάδα ελέγχου. Τα επίπεδά της δεν συσχετίστηκαν στατιστικά σημαντικά με τα επίπεδα αντίστασης στην ινσουλίνη αλλά κυρίως με παράγοντες όπως η γλυκόζη νηστείας, η ολική χοληστερόλη, τα επίπεδα σιδήρου καθώς και οι θυρεοειδικές ορμόνες και η παραθορμόνη. Ο δείκτης ΗΟΜΑ-IR βρέθηκε να σχετίζεται με τα σωματομετρικά χαρακτηριστικά των ασθενών. Συμπεράσματα: Τα επίπεδα της RBP-4 είναι αυξημένα στους αιμοκαθαιρόμενους ασθενείς. Φαίνεται δε πως η πρωτεΐνη αυτή εμπλέκεται σε μεταβολικά μονοπάτια χρόνιας φλεγμονής. Δεν βρέθηκε ωστόσο κάποια σημαντική συσχέτιση μεταξύ των επιπέδων της RBP-4 και της αντίστασης στην ινσουλίνη, όπως αυτή αξιολογήθηκε από τον δείκτη ΗΟΜΑ-IR. Συμπερασματικά, τα επίπεδα της RBP-4 θα μπορούσαν να αποτελέσουν ένα σημαντικό δείκτη για την αξιολόγηση του μεταβολικού προφίλ των αιμοκαθαιρόμενων ασθενών και δυνητικά να θεωρηθούν ένα υποστηρικτικό προγνωστικό εργαλείο για την παρακολούθηση της υγείας των ασθενών με χρόνια νεφρική νόσο