Ανάλυση Συναισθήματος και Εξόρυξη Κειμένου σε αξιολογήσεις στο TripAdvisor

Το αντικείμενο της παρούσας διπλωματικής εργασίας είναι η ανάλυση συναισθήματος σε δεδομένα της κοινωνικής πλατφόρμας TripAdvisor με την μέθοδο μη επιβλεπόμενης μάθησης βασισμένη σε λεξικό. Η ανάλυση συναισθήματος, που ονομάζεται επίσης εξόρυξη γνώμης (opinion mining), είναι ο τομέας της επιστήμης που αναλύει τις απόψεις, τα αισθήματα, τις εκτιμήσεις, τις στάσεις, τα συναισθήματα προς οντότητες και τα χαρακτηριστικά γνωρίσματά που εκφράζονται σε γραπτό κείμενο. Τα τελευταία χρόνια έχει παρουσιαστεί ραγδαία ανάπτυξη ως πεδίο έρευνας, εξαιτίας της μεγάλης επιρροής των κοινωνικών δικτύων και των πλατφόρμων κοινωνικής δικτύωσης στην καθημερινότητά μας, και λόγω του ότι παρέχει ένα αυτοματοποιημένο τρόπο για την ανάλυση της γραπτής πληροφορίας που αφθονεί στις διαδικτυακές πηγές. Η αναγνώριση του συναισθήματος γίνεται σε δύο κατηγορίες, θετικό και αρνητικό συναίσθημα και για τις ανάγκες της εργασίας χρησιμοποιείται ένα σύνολο από περίπου 50.047 αξιολογήσεων από τους χρήστες του TripAdvisor σχετικά με πέντε βασικά σημεία τουρισμού της Αθήνας. Το πρώτο μέρος της ανάλυσης αναφέρεται στην ανάκτηση των δεδομένων μέσω της χρήσης του scraping και αφού γίνει η προ-επεξεργασία των δεδομένων για όλους τους ειδικούς όρους που απαντώνται σε αυτά και μπορεί να δυσκολεύουν την ανάλυση τους, παράλληλα, εξετάζονται διάφοροι τρόποι εξαγωγής πληροφορίας από τα δεδομένα κειμένου και συγκεκριμένα η κλασσική μέθοδος Bag-of-Words με τις παραλλαγές term frequency και tf-idf (term frequency - inverse document frequency) και οι διανυσματικές αναπαραστάσεις λέξεων που καλούνται word vectors με την χρήση της γλώσσας python, της βιβλιοθήκης της pandas και του NRC-Emotion Lexicon. Οι παραπάνω ιδέες αξιολογούνται όλες στο σύνολο δεδομένων. Η εργασία καταλήγει στο συμπέρασμα πως οι τεχνικές ανάλυσης συναισθήματος μέσω της χρήσης λεξικού ανταποκρίνονται πολύ καλά στο πρόβλημα παρέχοντας γρήγορες υλοποιήσεις και αξιόπιστες επιδόσεις. Ακολουθώντας τις διαφορετικές μεθοδολογίες: (α) τη συχνότητα χρήσης μεμονωμένων λέξεων το σχήμα στάθμισης TF-IDF, (β) την εμφάνιση επιλεγμένων λέξεων πολικότητας με τη χρήση λεξικού καθώς και (γ) την τεχνική ομαδοποίησης K-means Clustering, παράγονται σημαντικές πληροφορίες σχετικά με την άποψη των χρηστών για τα πέντε αυτά τουριστικά σημεία της Αθήνας. Τα αποτελέσματα της μελέτης αυτής αποδεικνύουν ότι οι αξιολογήσεις των χρηστών, οι οποίες είναι γραμμένες στην αγγλική γλώσσα, είναι δυνατό να ταξινομηθούν, με βάση την συναισθηματική τους πολικότητα, με έναν πολύ αποτελεσματικό τρόπο, παράγοντας επαρκή συμπεράσματα. Η έρευνα αυτή μπορεί να βοηθήσει στην ελαχιστοποίηση του χρόνου που απαιτείται στην αναζήτηση εξόρυξη πληροφορίας σχετικά με τα πέντε τουριστικά σημεία μελέτης καθώς επίσης να βοηθήσει στην ανάπτυξη του τουρισμού στην περιοχή της Αθήνας και της Ελλάδας γενικότερα. Λέξεις Κλειδιά: Ανάλυση συναισθήματος, Εξόρυξη κειμένου, TripAdvisor, Κ-means ClusteringThe subject of this thesis is the analysis of sentiment in data on the social platform of TripAdvisor with the non-supervised lexical based learning method. Sentiment analysis, also called opinion mining, is the field of science that analyzes opinions, feelings, assessments, attitudes, feelings to entities, and features that are expressed in written text. Recent years have shown rapid growth as a research field, due to the great influence of social networks and social media platforms in our everyday lives, and because it provides an automated way to analyze the written information that abounds in online sources. Recognition of sentiment occurs in two categories, positive and negative emotions, and for the needs of work, a total of about 49,748 evaluations from the users of TripAdvisor on five key tourist spots in Athens are used. The first part of the analysis refers to the data recovery through the use of scraping and after pre-processing the data for all the specific terms encountered in them and can make their analysis difficult, while at the same time various ways of extracting information from the data and in particular the classical Bag-of-Words method with the term frequency and tf-idf (term frequency - inverse document frequency) variants and the vector representations of words called word vectors using the python language, the pandas library and the use of NRC-Emotion Lexicon. The above ideas are all evaluated in the dataset. The work concludes that speech-based emotional analysis techniques respond very well to the problem by providing quick implementations and reliable performance. Following different methods: (a) the frequency of use of individual words using the TF-IDF method, (b) the appearance of selected polarity of words using a dictionary, and (c) technical K-means Clustering, producing significant information on the users' view of these five tourist spots in Athens. The results of our study show that we can classify reviews written in English based on their emotional polarity in a very effective way. This research can help minimize the time needed to search for relevant information as well as help in the development of tourism in Athens and Greece in general

Non-Isothermal Crystallization Kinetics of PBSu/Biochar Composites Studied by Isoconversional and Model Fitting Methods

Non-isothermal crystallization of Poly(butylene succinate) (PBSu)/biochar composites was studied at various constant cooling rates using differential scanning calorimetry. The analysis of the kinetics data revealed that the overall crystallization rate and activation energy of the PBSu polymer were significantly influenced by the addition of biochar. Specifically, the PBSu/5% biochar composite with a higher filler content was more effective as a nucleation agent in the polymer matrix, as indicated by the nucleation activity (ψ) value of 0.45. The activation energy of the PBSu/5% biochar composite was found to be higher than that of the other compositions, while the nucleation activity of the PBSu/biochar composites decreased as the biochar content increased. The Avrami equation, which is commonly used to describe the kinetics of crystallization, was found to be limited in accurately predicting the non-isothermal crystallization behavior of PBSu and PBSu/biochar composites. Although the Nakamura/Hoffman–Lauritzen model performed well overall, it may not have accurately predicted the crystallization rate at the end of the process due to the possibility of secondary crystallization. Finally, the combination of the Šesták–Berggren model with the Hoffman–Lauritzen theory was found to accurately predict the crystallization behavior of the PBSu/biochar composites, indicating a complex crystallization mechanism involving both nucleation and growth. The Kg parameter of neat PBSu was found to be 0.7099 K2, while the melting temperature and glass transition temperature of neat PBSu were found to be 114.91 °C and 35 °C, respectively, very close to the measured values. The Avrami nucleation dimension n was found to 2.65 for PBSu/5% biochar composite indicating that the crystallization process is complex in the composites

The Effect of Biochar Addition on Thermal Stability and Decomposition Mechanism of Poly(butylene succinate) Bionanocomposites

In the present study, poly(butylene succinate) (PBSu) and its bionanocomposites containing 1, 2.5, and 5 wt.% biochar (MSP700) were prepared via in situ melt polycondensation in order to investigate the thermal stability and decomposition mechanism of the materials. X-ray photoelectron spectroscopy (XPS) measurements were carried out to analyze the surface area of a biochar sample and PBSu/biochar nanocomposites. From XPS, it was found that only physical interactions were taking place between PBSu matrix and biochar nanoadditive. Thermal stability, decomposition kinetics, and the decomposition mechanism of the pristine PBSu and PBSu/biochar nanocomposites were thoroughly studied by thermogravimetric analysis (TGA) and pyrolysis–gas chromatography/mass spectrometry (Py−GC/MS). TGA thermograms depicted that all materials had high thermal stability, since their decomposition started at around 300 °C. However, results indicated a slight reduction in the thermal stability of the PBSu biochar nanocomposites because of the potential catalytic impact of biochar. Py−GC/MS analysis was employed to examine, in more detail, the thermal degradation mechanism of PBSu nanocomposites filled with biochar. From the decomposition products identified by Py−GC/MS after pyrolysis at 450 °C, it was found that the decomposition pathway of the PBSu/biochar nanocomposites took place mainly via β-hydrogen bond scission, which is similar to that which took place for neat PBSu. However, at higher biochar content (5 wt.%), some localized differences in the intensity of the peaks of some specific thermal degradation products could be recognized, indicating that α-hydrogen bond scission was also taking place. A study of the thermal stability and decomposition pathway of PBSu/biochar bionanocomposites is crucial to examine if the new materials fulfill the requirements for further investigation for mulch films in agriculture or in electronics as possible applications

The effectiveness of a stress-management intervention program in the management of overweight and obesity in childhood and adolescence

Background: Obesity in childhood and adolescence represents a major health problem of our century, and accounts for a significant increase in morbidity and mortality in adulthood. In addition to the increased consumption of calories and lack of exercise, accumulating evidence suggests that childhood obesity is strongly associated with prolonged and excessive activation of the stress system. Aim: The aim of our study was to assess the effectiveness of a stress-management intervention program, which included progressive muscle relaxation, diaphragmatic breathing, guided imagery and cognitive restructuring, in overweight and obese children and adolescents. Methods: Forty-nine children and adolescents (mean age ± SEM: 11.15 ± 1.48 years) were prospectively recruited to participate in this randomized controlled study. Of those, 23 participants were assigned into the intervention group, while 26 participants represented the control group. Anthropometric measurements were recorded at the beginning and at the end of the study, and participants were asked to complete the Screen for Child Anxiety Related Disorders (S.C.A.R.E.D.), the Child Depression Inventory (C.D.I.), the Child Behavior Checklist (C.B.C.L.) and the Youth Self Report (Y.S.R.). Results: The applied stress-management methods resulted in a significant reduction in the body mass index (BMI) in the intervention group compared with the control group [ΔBMI=1.18 vs 0.10 kg/m2 (p˂0.001)]. In addition to BMI, these methods ameliorated depression and anxiety, and reduced the internalizing and externalizing problems in the intervention group. Conclusions: Our study demonstrated that the application of an 8-week stress management program could facilitate weight loss in Greek overweight and obese children and adolescents. Further larger studies are required to evaluate the effectiveness of stress-management methods in overweight and obese subjects

Chelator-free/chelator-mediated radiolabeling of colloidally stabilized iron oxide nanoparticles for biomedical imaging

The aim of this study was to develop a bioimaging probe based on magnetic iron oxide nanoparticles (MIONs) surface functionalized with the copolymer (p(MAA-g-EGMA)), which were radiolabeled with the positron emitter Gallium-68. The synthesis of the hybrid MIONs was realized by hydrolytic condensation of a single ferrous precursor in the presence of the copolymer. The synthesized MagP MIONs displayed an average D-h of 87 nm, suitable for passive targeting of cancerous tissues through the enhanced permeation and retention (EPR) effect after intravenous administration, while their particularly high magnetic content ascribes strong magnetic properties to the colloids. Two different approaches were explored to develop MIONs radiolabeled with Ga-68: the chelator-mediated approach, where the chelating agent NODAGA-NHS was conjugated onto the MIONs (MagP-NODAGA) to form a chelate complex with Ga-68, and the chelator-free approach, where Ga-68 was directly incorporated onto the MIONs (MagP). Both groups of NPs showed highly efficient radiolabeling with Ga-68, forming constructs which were stable with time, and in the presence of PBS and human serum. Ex vivo biodistribution studies of [Ga-68]Ga- MIONs showed high accumulation in the mononuclear phagocyte system (MPS) organs and satisfactory blood retention with time. In vivo PET imaging with [Ga-68]Ga-MagP MIONs was in accordance with the ex vivo biodistribution results. Finally, the MIONs showed low toxicity against 4T1 breast cancer cells. These detailed studies established that [Ga-68]Ga- MIONs exhibit potential for application as tracers for early cancer detection.Web of Science117art. no. 167

Development and validation of a framework for the assessment of school curricula on the presence of evolutionary concepts (FACE)

Evolution is a key concept of biology, fundamental to understand the world and address important societal problems, but research studies show that it is still not widely understood and accepted. Several factors are known to influence evolution acceptance and understanding, but little information is available regarding the impacts of the curriculum on these aspects. Very few curricula have been examined to assess the coverage of biological evolution. The available studies do not allow comparative analyses, due to the different methodologies employed by the authors. However, such an analysis would be useful for research purposes and for the development of appropriate educational policies to address the problem of a lack of evolution acceptance in some countries. In this paper we describe the steps through which we developed a valid and reliable instrument for curricula analysis known as FACE: “Framework to Assess the Coverage of biological Evolution by school curricula.” This framework was developed based on the “Understanding Evolution Conceptual Framework” (UECF). After an initial pilot study, our framework was reformulated based on identified issues and experts’ opinions. To generate validity and reliability evidence in support of the framework, it was applied to four European countries’ curricula. For each country, a team of a minimum of two national and two foreign coders worked independently to assess the curriculum using this framework for content analysis. Reliability evidence was estimated using Krippendorf's alpha and resulted in appropriate values for coding the examined curricula. Some issues that coders faced during the analysis were discussed and, to ensure better reliability for future researchers, additional guidelines and one extra category were included in the framework. The final version of the framework includes six categories and 34 subcategories. FACE is a useful tool for the analysis and the comparison of curricula and school textbooks regarding the coverage of evolution, and such results can guide curricula development.info:eu-repo/semantics/publishedVersio

Correction to: Development and validation of a framework for the assessment of school curricula on the presence of evolutionary concepts (FACE)

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