cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Ποιότητα σχέσης παιδαγωγού- μαθητή και βαθμός συμμετοχής στην τάξη:
Creators: name: Παπαδοπούλου, Ελένη Παύλου
Publisher: name: Aristotle University of Thessaloniki
Year: 2014
Subjects: αντιλήψεις παιδιών
ποιότητα σχέσης
βαθμός συμμετοχής
Children’s perceptions
quality of relationship
degree of engagement

description: Η παρούσα εργασία διερευνά την ποιότητα της σχέσης εκπαιδευτικού- μαθητή στη προσχολική εκπαίδευση. Παράλληλα εξετάζει το βαθμό επίδρασης της σχέσης αυτής στη συμμετοχή των μαθητών στις εκπαιδευτικές διαδικασίες και το βαθμό στον οποίο η καταγωγή των μαθητών τις διαφοροποιεί ή όχι. Τα εργαλεία μέτρησης που χρησιμοποιήθηκαν για τις ανάγκες της έρευνας ήταν τα ερωτηματολόγια Y-CATS και TREE. Τα ερευνητικά δεδομένα συλλέχτηκαν από 232 μαθητές νηπιαγωγείου κατά τους μήνες Απρίλιο και Μάιο σε Ανατολική και Κεντρική Μακεδονία στην Ελλάδα. Τα αποτελέσματα έδειξαν ότι τα παιδιά έχουν τη δυνατότητα να εκφράζουν τις αντιλήψεις τους έγκυρα και αξιόπιστα. Επιπρόσθετα, βρέθηκε ότι η μεταβλητή της σύγκρουσης, όπως την αντιλαμβάνονται οι μαθητές, συσχετίζεται θετικά με τη μη συμμετοχή τους στην τάξη και αρνητικά με τη συναισθηματική εγγύτητα.
description: The purpose of the present study was to investigate the quality of teacher-child relationship in preschool education. Additionally, the degree of children’s engagement, its correlations with the teacher-child relationship quality and the extent to which the origin differentiates or not, were examined. The questionnaires Y-CATS and TREE were the measurement instruments that were used by the researchers. The data were collected from 232 kindergarten students during April and May in East and Central Macedonia in Greece. The results supported that children have the ability to express their perceptions with reliability and validity. In addition, the “conflict” factor appeared to have positive correlation with the factor of “no engagement in classroom” and negative correlation with the factor of “closeness”.
Ο Κωνσταντίνος Θ΄ Μονομάχος μέσα από την ιστοριογραφία του 11ου αιώνα:
Creators: name: Κοτζαγιαννίδου, Κωνσταντία Παύλου
Publisher: name: Aristotle University of Thessaloniki
Year: 2014
Subjects: Μονομάχος
Ιστοριογραφία
Φιλολογία
Monomachus
Historiography
Philology

description: Σκοπός της διατριβής είναι η παρουσίαση του αυτοκράτορα Κωνσταντίνου Θ´ Μονομάχου μέσα από την ιστοριογραφία του 11ου αιώνα. Περιγράφεται η καταγωγή του αυτοκράτορα και αναλύεται λεπτομερώς η διαδικασία ανόδου του στο θρόνο. Στη συνέχεια ακολουθούν χωρία βυζαντινών ιστοριογράφων με λεπτομερείς περιγραφές της εξωτερικής μορφής του Κωνσταντίνου Θ´ Μονομάχου. Ιδιαίτερη έμφαση δίνεται τόσο στην εσωτερική όσο και στην εξωτερική πολιτική που ασκήθηκε, μέσα στο ιστορικό πλαίσιο για το οποίο γίνεται λόγος. Αναφέρονται τα αίτια που η συγκεκριμένη προσωπικότητα προκάλεσε ποικίλες συζητήσεις , πυροδότησε έντονες διαφωνίες και απασχόλησε ποικιλοτρόπως της ιστορικούς. Κατατίθενται απόψεις των ιστορικών Μιχαήλ Ψελλού, Μιχαήλ Ατταλειάτη, Ιωάννη Σκυλίτζη και Ιωάννη Ζωναρά, οι οποίες παρουσιάζουν εξαιρετικό ενδιαφέρον δεδομένου ότι είναι αντικρουόμενες καταμαρτυρώντας συμπάθειες ή αντιπάθειες. Ακολουθούν αναφορές στην ασθένεια που ταλαιπώρησε τον αυτοκράτορα και τέλος στο θάνατό του. Ξεχωριστή μνεία γίνεται και της απόψεις των νεότερων μελετητών , οι οποίοι υπήρξαν ομοίως αυστηροί μαζί του αλλά σίγουρα του αναγνώρισαν τα πολλαπλά και πολυδιάστατα αποτελέσματα της αυτοκρατορίας του . Τέλος , γίνεται μια αποτίμηση του συνόλου του διοικητικού έργου του Κωνσταντίνου Θ´ Μονομάχου και εν γένει της αυτοκρατορικής του διαδρομής.
description: The objective of this study is to present the emperor Constantine Monomachos through the historiography of the 11th century. The origin of the emperor is examined and the ascension to the throne is analyzed in detail. Furthermore, his outward appearance is thoroughly described based on the descriptions contained in byzantine historiographers’ passages. Particular emphasis is put on both the internal and the external policy that was exerted by the emperor within the historical context that is described. Moreover, it is provided an indication of the reasons that this particular personality generated various discussions, sparked a great deal of heated debate and concerned historians in various ways. The opinions of the historians Michael Psellos, Michael Attaleiates, John Skylitzes and John Zonaras are also provided. These opinions are very interesting due to the fact that they are opposed to each other, indicating sympathies or aversions. Additionally, references to the disease that wracked the emperor, and finally led to his death, are presented. A special attention is paid to the viewpoints of younger researchers who, although they were strict with him, they absolutely recognize the multiple and multidimensional effects of his empire. Finally, an evaluation of the total administrative work of Constantine Monomachos, and of the empire in general, is executed.
Hawking radiation from rotating black holes in anti-de Sitter spaces via gauge and gravitational anomalies
Creators: name: Jiang, Qing-Quan
name: Wu, Shuang-Qing
Publisher: name: arXiv
Year: 2007
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Astrophysics (astro-ph)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: Robinson-Wilczek's recent work, which treats Hawking radiation as a compensating flux to cancel gravitational anomaly at the horizon of a Schwarzschild-type black hole, is extended to study Hawking radiation of rotating black holes in anti-de Sitter spaces, especially that in dragging coordinate system, via gauge and gravitational anomalies. The results show that in order to restore gauge invariance and general coordinate covariance at the quantum level in the effective field theory, the charge and energy flux by requiring to cancel gauge and gravitational anomalies at the horizon, must have a form equivalent to that of a $(1+1)$-dimensional blackbody radiation at Hawking temperature with an appropriate chemical potential.
description: 15 pages
Σύνθεση και μελέτη της δομής συμπλόκων ενώσεων με ligand υποκατεστημένη τερπυριδίνη και πυριδινο- προπενόνη:
Creators: name: Ιορδανίδου, Δόμνα Γεωργίου
Publisher: name: Aristotle University of Thessaloniki
Year: 2014
Subjects: Χημεία
Σύμπλοκα
Τερπυριδίνη
Chemistry
Complexes
Terpyridine

description: Στην παρούσα εργασία έγινε η σύνθεση και η μελέτη των ligands της 4΄-(4-κυανοφαίνυλο)τερπυριδίνης και της πυριδινο-προπενόνης. Τα ligands χαρακτηρίστηκαν από φασματοσκοπία υπερύθρου (IR), υπεριώδους- ορατού (UV- Vis), φθορισμού και πυρηνικού μαγνητικού συντονισμού (NMR), έγινε θεωρητική μελέτη και μελέτη της ηλεκτροχημείας τους και λήφθηκε με ακτίνες-X η δομή του δεύτερου ligand. Κατόπιν παρασκευάστηκαν τα σύμπλοκα της 4΄-(4-κυανοφαινυλο)τερπυριδίνης με κοβάλτιο, χαλκό, νικέλιο και ψευδάργυρο και της πυριδινο-προπενόνης με ψευδάργυρο και μελετήθηκαν με φασματοσκοπία υπερύθρου (IR), υπεριώδους- ορατού (UV-Vis), φθορισμού και πυρηνικού μαγνητικού συντονισμού (NMR) ενώ έγιναν αγωγιμομετρικές και μαγνητικές μετρήσεις και λήφθηκαν πέντε δομές αυτών των συμπλόκων με ακτίνες- X. Από τις στοιχειακές μετρήσεις προκύπτει ότι η αναλογία μετάλλου- ligands είναι 1:2, εκτός από την περίπτωση του συμπλόκου του δισθενούς χαλκού. Στη συνέχεια, παρασκευάστηκε το μικτό σύμπλοκο του κοβαλτίου με την 4΄-(4-κυανοφαινυλο)τερπυριδίνη και την 4΄-(4-μεθυλφαινυλο)τερπυριδίνη και μελετήθηκε η δομή του συμπλόκου αυτού. Από φασματοσκοπία φθορισμού προκύπτει ότι το ligand και τα παραπάνω σύμπλοκα εμφανίζουν TICT συμπεριφορά.
description: In this study we made the synthesis and study of ligands of 4΄-(4-cyanophenyl) terpyridine and pyridine-propenone. The ligands were characterized by infrared spectroscopy (IR), ultraviolet– visible spectroscopy (UV-Vis), fluorescence spectroscopy and nuclear magnetic resonance (NMR), was theoretical studied and were taken measurements of electrochemistry and X -ray structure of the second ligand. Then we prepared the complexes of 4΄-(4-cyanophenyl)terpyridine with cobalt, copper, nickel and zinc and the complex of pyridine-propenone with zinc and we have studied them by infrared spectroscopy (IR), ultraviolet-visible spectroscopy (UV-Vis), fluorescence spectroscopy and nuclear magnetic resonance (NMR) and were taken conductivity and magnetic measurements and five structures of these complexes by X- ray. The elemental measurements show that the proportion of metal -ligands is 1:2, except in the case of the complex of bivalent copper. Then there was prepared a mixed cobalt complex with 4΄-(4-cyanophenyl)terpyridine and 4΄-(4-methylphenyl)terpyridine and studied the structure of this complex. The fluorescence spectroscopy shows that the ligand and the above complexes exhibit TICT behavior.
High-dimensional analysis of semidefinite relaxations for sparse principal components
Creators: name: Amini, Arash A.
name: Wainwright, Martin J.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Statistics Theory (math.ST)
subject: Information Theory (cs.IT)
subject: FOS: Mathematics
subject: FOS: Computer and information sciences
subject: 62H25 (Primary) 62F12 (Secondary)

description: Principal component analysis (PCA) is a classical method for dimensionality reduction based on extracting the dominant eigenvectors of the sample covariance matrix. However, PCA is well known to behave poorly in the ``large $p$, small $n$'' setting, in which the problem dimension $p$ is comparable to or larger than the sample size $n$. This paper studies PCA in this high-dimensional regime, but under the additional assumption that the maximal eigenvector is sparse, say, with at most $k$ nonzero components. We consider a spiked covariance model in which a base matrix is perturbed by adding a $k$-sparse maximal eigenvector, and we analyze two computationally tractable methods for recovering the support set of this maximal eigenvector, as follows: (a) a simple diagonal thresholding method, which transitions from success to failure as a function of the rescaled sample size $θ_{\mathrm{dia}}(n,p,k)=n/[k^2\log(p-k)]$; and (b) a more sophisticated semidefinite programming (SDP) relaxation, which succeeds once the rescaled sample size $θ_{\mathrm{sdp}}(n,p,k)=n/[k\log(p-k)]$ is larger than a critical threshold. In addition, we prove that no method, including the best method which has exponential-time complexity, can succeed in recovering the support if the order parameter $θ_{\mathrm{sdp}}(n,p,k)$ is below a threshold. Our results thus highlight an interesting trade-off between computational and statistical efficiency in high-dimensional inference.
description: Published in at http://dx.doi.org/10.1214/08-AOS664 the Annals of Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical Statistics (http://www.imstat.org)
Η αντιμετώπιση της τρομοκρατίας από την ελληνική έννομη τάξη με τους νόμους 2928/2001 και 3251/2004 για το οργανωμένο έγκλημα και τις τρομοκρατικές πράξεις:
Creators: name: Θεοχάρης, Θεοχάρης Χρήστου
Publisher: name: Aristotle University of Thessaloniki
Year: 2014
Subjects: Τρομοκρατία
Οργανωμένο έγκλημα
Οι νόμοι 2928/2001 και 3251/2004
Terrorism
Organized crime
The laws 2928/2001 and 3251/2004

description: Σκοπός της διπλωματικής μεταπτυχιακής εργασίας ήταν η καταγραφή και η αξιολόγηση της πορείας της αντιμετώπισης του τρομοκρατικού φαινομένου στην Ελλάδα από τη μεταπολίτευση και εντεύθεν, καθώς και η παρουσίαση, μελέτη και κριτική προσέγγιση των νόμων 2928/2001 και 3251/2004. Αρχικά έγινε μια σύντομη ιστορική αναδρομή, ενώ στη συνέχεια ακολούθησε μια θεωρητική προσέγγιση του ζητήματος του ορισμού του τρομοκρατικού εγκλήματος. Κατόπιν εξετάστηκαν οι νομοθετικές πρωτοβουλίες της ελληνικής έννομης τάξης με εμβάθυνση στους προαναφερθέντες νόμους. Δόθηκε έμφαση στις σημαντικές τομές που συντελέστηκαν στο ποινικό δίκαιο της χώρας με την ενσωμάτωση της σχετικής απόφασης – πλαίσιο του Συμβουλίου, στις νέες «ειδικές» ανακριτικές πράξεις καθώς και στον ορατό κίνδυνο διεύρυνσης του κύκλου των ατόμων, που πιθανόν να εμπλακούν με την ποινική καταστολή. Τέθηκαν ζητήματα ατομικών δικαιωμάτων και στάθμισής τους με τους κινδύνους και τις απειλές, που απορρέουν για τα έννομα αγαθά των πολιτών από το τρομοκρατικό έγκλημα αλλά και από την αντιμετώπισή του.
description: The aim of the present thesis was to identify and evaluate the progress of addressing the terrorist phenomenon in Greece from the dictatorship onwards and to present, study and critically approach the laws 2928/2001 and 3251/2004. Initially there was a literature review on the history of the terrorist crime and its definition. Then an examination of the legislative initiatives of the Greek legal order followed with a focus on the aforementioned laws. Emphasis was placed on the significant changes that have occurred in the criminal law of the country with the integration of the related council’s framework - decision, on the new "special" interrogation acts and also on the foreseeable risk of widening the circle of people likely to engage with criminal enforcement. Issues were raised about the individual rights in relation with the risks and threats posed on the legal rights of the citizens by the terrorist crime but also by the efforts to address it.
Multimodal optical systems for clinical oncology
Creators: name: Horgan, Conor Ciaran
Publisher: name: Imperial College London
Year: 2019

description: This thesis presents three multimodal optical (light-based) systems designed to improve the capabilities of existing optical modalities for cancer diagnostics and theranostics. Optical diagnostic and therapeutic modalities have seen tremendous success in improving the detection, monitoring, and treatment of cancer. For example, optical spectroscopies can accurately distinguish between healthy and diseased tissues, fluorescence imaging can light up tumours for surgical guidance, and laser systems can treat many epithelial cancers. However, despite these advances, prognoses for many cancers remain poor, positive margin rates following resection remain high, and visual inspection and palpation remain crucial for tumour detection. The synergistic combination of multiple optical modalities, as presented here, offers a promising solution. The first multimodal optical system (Chapter 3) combines Raman spectroscopic diagnostics with photodynamic therapy using a custom-built multimodal optical probe. Crucially, this system demonstrates the feasibility of nanoparticle-free theranostics, which could simplify the clinical translation of cancer theranostic systems without sacrificing diagnostic or therapeutic benefit. The second system (Chapter 4) applies computer vision to Raman spectroscopic diagnostics to achieve spatial spectroscopic diagnostics. It provides an augmented reality display of the surgical field-of-view, overlaying spatially co-registered spectroscopic diagnoses onto imaging data. This enables the translation of Raman spectroscopy from a 1D technique to a 2D diagnostic modality and overcomes the trade-off between diagnostic accuracy and field-of-view that has limited optical systems to date. The final system (Chapter 5) integrates fluorescence imaging and Raman spectroscopy for fluorescence-guided spatial spectroscopic diagnostics. This facilitates macroscopic tumour identification to guide accurate spectroscopic margin delineation, enabling the spectroscopic examination of suspicious lesions across large tissue areas. Together, these multimodal optical systems demonstrate that the integration of multiple optical modalities has potential to improve patient outcomes through enhanced tumour detection and precision-targeted therapies.
The future cost of electricity storage and its value in low-carbon power systems
Creators: name: Schmidt, Oliver Lutz
Publisher: name: Imperial College London
Year: 2019

description: The energy sector is transforming rapidly to reduce carbon emissions and limit global climate change. Electricity storage can provide the required flexibility to balance intermittent and relatively inflexible power generation with demand in low-carbon power systems. However, falling investment cost, the wide range of technologies with different performance characteristics and the wide range of use cases with different performance requirements lead to uncertainty on its commercial viability. To assess electricity storage against alternatives and enable further investment in low-carbon technologies, policy-makers and industry need certainty on cost reduction potentials and its value in enabling low-carbon power systems. This thesis creates an experience curve dataset for 11 electricity storage technologies, identifying investment cost reductions to US$325±125/kWh (systems) and US$155±45/kWh (packs) once 1 TWh capacity is installed for each technology. This could be achieved by 2027–2040 based on market growth projections. Expert interviews highlight the importance of production scale-up as cost reduction driver and provide a detailed list of technical and value chain innovations for two prominent storage technologies. The quantification of future application-specific lifetime cost with a novel, comprehensive formula, that accounts for all relevant cost and performance parameters, indicates that lithium ion will be the most cost competitive for most applications by 2030. Lower financing cost, in general, and performance improvements for alternative technologies specifically could challenge this dominance. Matching future lifetime cost to revenue potentials across applications reveals profitable business cases in three distinct application categories with specific requirements. An analysis of modelled flexibility capacity in power system studies reveals two approaches to assess electricity storage capacity requirements in low-carbon power systems. In both approaches, the flexibility capacity requirement relative to peak demand increases linearly with increasing wind, solar and nuclear penetration, albeit at different rates, requiring up to 65% or 115% in a fully decarbonised power system. These insights combined with the online availability of experience curve dataset and lifetime cost tool increase transparency on the future cost of electricity storage and its value in low-carbon power systems, supporting policy and industry in transforming the energy sector.
Einstein's equations as a thermodynamic identity: The cases of stationary axisymmetric horizons and evolving spherically symmetric horizons
Creators: name: Kothawala, Dawood
name: Sarkar, Sudipta
name: Padmanabhan, T.
Publisher: name: arXiv
Year: 2007
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: Astrophysics (astro-ph)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: There is an intriguing analogy between the gravitational dynamics of the horizons and thermodynamics. In case of general relativity, as well as for a wider class of Lanczos-Lovelock theories of gravity, it is possible to interpret the field equations near any spherically symmetric horizon as a thermodynamic identity TdS = dE + PdV. We study this approach further and generalize the results to two more generic cases within the context of general relativity: (i) stationary axis-symmetric horizons and (ii) time dependent evolving horizons. In both the cases, the near horizon structure of Einstein equations can be expressed as a thermodynamic identity under the virtual displacement of the horizon. This result demonstrates the fact that the thermodynamic interpretation of gravitational dynamics is not restricted to spherically symmetric or static horizons but is quite generic in nature and indicates a deeper connection between gravity and thermodynamics.
description: revtex; 6 pages; no figures
Observation and simulation of atmospheric carbon dioxide in Vancouver
Creators: name: Reid, Kenneth Howard
Publisher: name: University of British Columbia
Year: 2009

description: Climate change expected from increasing atmospheric CO₂ concentrations has been studied widely (IPCC, 1990). Further, it is recognized that cities are a major source of anthropogenic CO₂. However, few studies of CO₂ concentrations in, or near, cities have been conducted. A LI-COR infrared gas analyzer was operated at the Sunset Tower in a suburban region of Vancouver during different time periods in 1993 and 1994. Sampling revealed important information on seasonal and diurnal variations. The observed summertime concentrations show a clear diurnal signal around the expected upwind background concentration, and are described by a late afternoon minimum, and overnight maximum. The afternoon CO₂ minimum is attributed to the strength of biospheric photosynthesis and strong mixing of local anthropogenic sources within a large mixed layer. Poor nighttime mixing, lower mixed depths, and biospheric respiration account for the observed nighttime maximum, often more than 80 ppmv greater than the background concentration. A simple numerical multiple-box transport model was developed to simulate the observed diurnal pattern of CO₂ concentration at the suburban site. CO₂ emissions inventories for important mobile sources, stationary sources, and biospheric sources and sinks are calculated as input to the model for upwind fetch areas. Other CO₂ inputs include advection, entrainment from above the mixed layer and determination of the mixed layer depth. Results of both observations and modelling show large diurnal variation in CO₂ concentrations, and the importance of boundary layer structure (as defined by the mixed layer) on concentrations at a specific location. In terms of CO₂, the role of the city is placed in it global context.
The effect of siderophores on the aqueous chemistry of uranium VI: a combined experimental and computational approach
Creators: name: Kirby, Matthew Edward
Publisher: name: Imperial College London
Year: 2019

description: Understanding aqueous uranium VI (UVI) chemistry in alkaline environments (pH >10) is crucial as radioactive waste can be stored and disposed in these conditions. Naturally occurring organic molecules can interact with UVI, modifying its aqueous chemistry and subsequent groundwater facilitated transport. The aim of this research project is to characterise the effect of the (tris)hydroxamate siderophore desferrioxamine B (DFOB) on UVI aqueous chemistry in alkaline solutions. Initially, the physico-chemical properties of UVI precipitates were characterised in solutions containing 42 µM UVI and 0.1 M NaCl. UVI formed 640 ± 111 and 837 ± 142 nm diameter Na6U7O24 precipitates at pH 10.5 and 11.5 respectively. These were usually physically immobilised in quartz sand columns. When ≥130 µM DFOB was simultaneously added with UVI to pH 11.5, 0.1 M NaCl solutions, UVI quantitatively passes through 0.2 µm filter membranes. This could be due to the formation of an aqueous UVI-DFOB complex as observed below pH 10. To further explore complex formation, a density functional theory protocol was established. The protocol predicts the stability constants (log β) of UVI-organic ligand complexes with root mean square deviation of 1.19 log β units after calibration against experimental data collected in acidic solutions. The relative stability series for UVI complexes with key siderophore functional groups calculated using the fitting equation is: α-hydroxycarboxylate bound via the α-hydroxy and carboxylate groups (log β110 = 17.08), α-hydroxyimidazolate (log β110 = 16.55), catecholate (log β110 = 16.43), hydroxamate (log β110 = 9.00), hydroxy-phenyloxazolonate (log β110 = 8.43) and α-aminocarboxylate (log β110 = 4.73). Finally the DFT protocol was adapted so that the stability of UVI-hydroxamate complexes can be approximated at pH 11.5. This suggests DFOB complexes in a monodentate fashion via one hydroxamate group. These results highlight the significant effect siderophores can play on aqueous UVI chemistry.
Patient-specific analysis of the hemodynamic performance of surgical and transcatheter aortic valve replacements
Creators: name: Pirola, Selene
Publisher: name: Imperial College London
Year: 2019

description: Aortic valve (AV) diseases are life-threatening conditions which affect millions of people worldwide and, if left untreated, can lead to death a few years after symptom onset. Patients affected by AV diseases are commonly referred to surgical AV replacement (SAVR). However, more than 30% of patients are not suitable for SAVR. For this reason, transcatheter aortic valve implantation (TAVI) has been attracting growing interest. Several clinical studies compared the outcomes of these techniques, showing that TAVI could be a valid alternative to SAVR. However, there is a lack of detailed knowledge about changes in the aortic hemodynamic conditions following these procedures. The main aim of this thesis is to develop efficient and robust methodologies to study and compare the influences of different AV replacement procedures on aortic hemodynamics. An image-based patient-specific computational model has been developed, which uses magnetic resonance images (MRI) acquired from patients to obtain realistic geometry and boundary conditions (BCs) for computational fluid dynamics (CFD) analysis. The implemented physiological BCs were compared with the most commonly used inlet and outlet BCs, and showed the best agreement with in vivo data. The model was then applied to study and compare SAVR, TAVI and aortic root replacement using a variety of prostheses. In addition, an experimental set-up was designed to further study TAVI hemodynamics by combining 3D-printing, 4D flow MRI and CFD. Finally, a preliminary analysis of valve leaflet thrombosis was conducted. It has been shown that both TAVI and SAVR are able to greatly improve the aortic hemodynamics, but this often deviates from conditions in healthy volunteers, with the extent of abnormalities strongly dependent on the type of prostheses or valve disease. The work also demonstrated the feasibility of predicting valve leaflet thrombosis using a shear-driven model for thrombus formation and growth.
Statistical mechanics of the shallow-water system with a prior potential vorticity distribution
Creators: name: Chavanis, P. H.
name: Dubrulle, B.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Fluid Dynamics (physics.flu-dyn)
subject: FOS: Physical sciences

description: We adapt the statistical mechanics of the shallow-water equations to the case where the flow is forced at small scales. We assume that the statistics of forcing is encoded in a prior potential vorticity distribution which replaces the specification of the Casimir constraints in the case of freely evolving flows. This determines a generalized entropy functional which is maximized by the coarse-grained PV field at statistical equilibrium. Relaxation equations towards equilibrium are derived which conserve the robust constraints (energy, mass and circulation) and increase the generalized entropy.
Level rearrangement in exotic atoms and quantum dots
Creators: name: Combescure, Monique
name: Khare, Avinash
name: Raina, Ashok
name: Richard, Jean-Marc
name: Weydert, Carole
Publisher: name: arXiv
Year: 2007
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Nuclear Theory (nucl-th)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: A presentation and a generalisation are given of the phenomenon of level rearrangement, which occurs when an attractive long-range potential is supplemented by a short-range attractive potential of increasing strength. This problem has been discovered in condensate-matter physics and has also been studied in the physics of exotic atoms. A similar phenomenon occurs in a situation inspired by quantum dots, where a short-range interaction is added to an harmonic confinement.
description: 12 pages, 11 figures, RevTeX4
New type scalar fields for cosmic acceleration
Creators: name: Kehagias, Alex
Publisher: name: arXiv
Year: 2006
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Astrophysics (astro-ph)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We present a model where a non-conventional scalar field may act like dark energy leading to cosmic acceleration. The latter is driven by an appropriate field configuration, which result in an effective cosmological constant. The potential role of such a scalar in the cosmological constant problem is also discussed.
description: 6 pages
Grafo de cobertura tematica das Revistas Ciência da Informação, Liinc em Revista e Transinformação
Creators: name: Brito, Ronnie F.
Publisher: name: Zenodo
Year: 2022

description: Grafo de cobertura tematica gerado a partir da extracao de termos dos corpora das revistas e do Tesauro Brasileiro de Ciencia da Informacao
Experimental and numerical investigation of stress-relaxation age forming of AA6082
Creators: name: Rong, Qi
Publisher: name: Imperial College London
Year: 2019

description: This thesis presents a comprehensive experimental and modelling investigation of stress-relaxation ageing of AA6082. Based on this investigation, successful manufacture of a typical industrial component with large and complex curvatures and with high dimensional accuracy has been achieved through the stress-relaxation age forming (SRAF) process. The 12 hr stress-relaxation ageing behaviour in both the elastic and plastic regions of AA6082-T6 at 160 °C has been experimentally investigated for the first time, including stress-relaxation ageing tests, tensile tests, and microstructural observations. It has been observed that the total stress relaxed after a 12 hr test increases significantly with increasing initial strain levels, while the initial strain levels contribute little effect to the yield strength evolution during stress-relaxation ageing. Microstructural observation results and the stress exponent method have been used to analyse the stress-relaxation mechanisms of the material, and a decreasing threshold stress with increasing initial strain is proposed for stress-relaxation ageing in the plastic region. A new unified constitutive model has been proposed and calibrated to accurately predict both the stress-relaxation behaviour and the yield strength evolutions of AA6082-T6 during the SRAF process in both the elastic and plastic regions. FE simulations of the SRAF process have been carried out using the FE solver ABAQUS, in which the developed material model has been implemented through the user-defined CREEP subroutine, and their effectiveness has been validated by SRAF tests of a singly-curved plate. A springback compensation strategy has been developed for tool shape compensation and its effectiveness proved by SRAF tests of a doubly-curved plate. Finally, an industrial component with large and complex curvatures, which was selected from an in-service high-speed train, has been successfully manufactured through the SRAF process with the integrated numerical technologies developed in this thesis, including material and FE simulation models, and a springback compensation strategy. The successful production of the industrial component has proven the feasibility of the developed technologies, which can be used as an effective tool to guide the future industrial applications of the SRAF process with AA6082 alloy.
The onset of X-ray emission in young stellar objects: a Chandra observation of the Serpens star-forming region
Creators: name: Giardino, G.
name: Favata, F.
name: Micela, G.
name: Sciortino, S.
name: Winston, E.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: AIMS: To study the properties of X-ray emissions from young stellar objects (YSOs), through their evolution from Class I to Class III and determine whether Class 0 protostars emit in X-rays. METHODS: A deep Chandra X-ray observation of the Serpens star-forming region was obtained. The Serpens Cloud Core is ideally suited for this type of investigation, being populated by a dense and extremely young cluster whose members are found in all different evolutionary stages, including six well studied Class 0 sources. RESULTS: None of the six Class 0 protostars is detected in our observations, excluding the presence of sources with X-ray luminosities > 0.4 10^30 erg/s (for column densities of the order of 4 10^{23} cm^-2, or A_V ~ 200). A total of 85 X-ray sources are detected and the light curves and spectra of 35 YSOs are derived. There is a clear trend of decreasing absorbing column densities as one moves from Class I to Class III sources, and, possibly, evidence of decreasing plasma temperatures, too. We observe a strong, long-duration, flare from a Class II low-mass star, for which we derive a flaring loop length of the order of 20 stellar radii. We interpret the flaring event as originating from a magnetic flux tube connecting the star to its circumstellar disk. The presence of such a disk is supported by the detection, in the spectrum of this star, of 6.4 keV Fe fluorescent emission.
description: Accepted for publication in A&A
Entropy of Null Surfaces and Dynamics of Spacetime
Creators: name: Padmanabhan, T.
name: Paranjape, Aseem
Publisher: name: arXiv
Year: 2007
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: Astrophysics (astro-ph)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: The null surfaces of a spacetime act as one-way membranes and can block information for a corresponding family of observers (time-like curves). Since lack of information can be related to entropy, this suggests the possibility of assigning an entropy to the null surfaces of a spacetime. We motivate and introduce such an entropy functional for any vector field in terms of a fourth-rank divergence free tensor P_{ab}^{cd} with the symmetries of the curvature tensor. Extremising this entropy for all the null surfaces then leads to equations for the background metric of the spacetime. When P_{ab}^{cd} is constructed from the metric alone, these equations are identical to Einstein's equations with an undetermined cosmological constant (which arises as an integration constant). More generally, if P_{ab}^{cd} is allowed to depend on both metric and curvature in a polynomial form, one recovers the Lanczos-Lovelock gravity. In all these cases: (a) We only need to extremise the entropy associated with the null surfaces; the metric is not a dynamical variable in this approach. (b) The extremal value of the entropy agrees with standard results, when evaluated on-shell for a solution admitting a horizon. The role of full quantum theory of gravity will be to provide the specific form of P_{ab}^{cd} which should be used in the entropy functional. With such an interpretation, it seems reasonable to interpret the Lanczos-Lovelock type terms as quantum corrections to classical gravity.
description: revised version with significantly generalised perspective; references added
The influence of solute diffusion and anisotropic elasticity on the deformation of iron: a study using planar discrete dislocation plasticity
Creators: name: White, William
Publisher: name: Imperial College London
Year: 2019

description: Plastic deformation of crystalline metals is facilitated by crystallographic defects called dislocations. In certain alloys at certain temperatures and loading rates, the motion of these dislocations can become chaotic and unstable. This is a phenomenon related to dynamic strain ageing called the Portevin–Le Châtelier effect. The effect occurs when impurities, such as carbon and nitrogen, segregate to dislocations and obstruct their motion, leading to reduced ductility, hardening, and in the worst case, mechanical failure. In this thesis, I model plasticity with planar discrete dislocation plasticity. I extend planar discrete dislocation plasticity using anisotropic elasticity and introduce discrete diffusing solutes. This is used to understand the deformation of iron; and the onset and progression of the Portevin– Le Châtelier effect. Results from the model show that the nature of the diffusing solute field significantly affects the manifestation of the Portevin–Le Châtelier effect. As the solute concentration increases, the iron specimen’s proof stress, flow stress and solute strengthening increases; and the serrations recorded in a stress-strain curve (symptomatic of the Portevin–Le Châtelier effect) become smaller and occur at a slower frequency. Conversely, as the solute diffusivity increases, the serrations become larger and occur at a faster frequency. Furthermore, I show that anisotropic elasticity alters the mechanisms of plastic deformation of α-iron at elevated temperatures; specifically, that a<100> type edge dislocations, which are energetically unfavourable at moderate temperatures, are nucleated in increasing numbers. This agrees with experimental observations found in the literature but cannot be predicted by isotropic elastic models. The increase in a<100> edge dislocations is symptomatic of the precipitous decrease in the yield strength of iron. My work has important consequences for the application of steels in elevated temperature environments such as generation IV very high temperature nuclear fission reactors.
Η ψυχή του ανθρώπου κατά τον Νικήτα Στηθάτο:
Creators: name: Γραμμενούδη, Παναγιώτα Στέφανου
Publisher: name: Aristotle University of Thessaloniki
Year: 2014
Subjects: Στηθάτος
Ψυχή
Άνθρωπος
Stethatos
Soul
Human

description: Αν θα θέλαμε να συνοψίσουμε τα κύρια σημεία του έργου του Νικήτα Στηθάτου για την ψυχή, θα λέγαμε ότι η ψυχή του ανθρώπου δημιουργήθηκε από το θείο εμφύσημα, από τη δημιουργική δύναμη του Θεού και όχι από τη θεία ουσία. Η ψυχή είναι αδιαίρετη και ενιαία, παράλληλα όμως είναι και πολυδύναμη. Διακρίνεται σε δύο μέρη στο λογικό και στο άλογο. Τα πάθη της ψυχής δεν βρίσκονται στη φύση του ανθρώπου αλλά αποτελούν εκτροπή της φυσιολογικής λειτουργίας και κίνησης της ψυχής. Αφού η ψυχή έχει παραστρατήσει από τον ορθό προσανατολισμό της και τον θεϊκό προορισμό της, χρειάζεται να διέλθει από διάφορα προπαρασκευαστικά στάδια για να ανυψωθεί και να φτάσει στην εν Χριστώ τελειότητα. Τέλος η ψυχή ως αθάνατη συνεχίζει την ύπαρξή της και μετά τον θάνατο του ανθρώπου. Η κατάσταση της ψυχής, καθώς και ο τόπος παραμονής της κατά την μεταθανάτια ζωή της εξαρτάται αποκλειστικώς από τη διαγωγή της κατά την επίγεια ζωή της.
description: The aim of the present thesis is to investigate the meaning of human soul and how it appears at the work of Nicetas Stethatos. We could say that it was created by the divine dlow, from the creative strength of God and not from God's substance. The soul is indivisible and at the same time it is multipotem. It is distinguished in two parts the logical and the illogical one. The passions of the soul are not part of the human nature but they constitute deviations. If the soul with passions and sins lost the way to God it has to pass from some stages to come back to the path of God. Finally the soul being immortal continues its existence after death as well. Its situation as well as the place it is going to stay depends on the way it has lived throughout its life, that is, whether it's been sinful or pure.
The Collaboration Between Neurosurgeons and Radiologists: Historical Developments and Impacts
Creators: name: Farooq, Mustafa
name: Farooq, Maheen
name: Mehra, Mehul
Publisher: name: History of Radiology
Year: 2024

description: The review article The Collaboration Between Neurosurgeons and Radiologists: Historical Developments and Impacts by Mustafa Farooq, Maheen Farooq, and Mehul Mehra explores the crucial partnership between radiologists and neurosurgeons that has shaped modern neurosurgical practices. Tracing the evolution from early X-rays to advanced imaging techniques like CT, MRI, and functional MRI (fMRI), the article highlights how radiology has enabled neurosurgeons to diagnose and treat brain conditions with increasing precision. The collaboration has been further enhanced by intraoperative imaging and real-time decision-making during surgeries. The article also examines emerging technologies such as artificial intelligence (AI) and augmented reality (AR), which promise to deepen this interdisciplinary relationship, further improving patient outcomes in neurosurgical oncology.
Azimuth quadrupole component spectra on transverse rapidity ${\bf y_t}$ for identified hadrons from Au-Au collisions at $\sqrt{s_{NN}} =$ 200 GeV
Creators: name: Trainor, Thomas A.
Publisher: name: arXiv
Year: 2008
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: I present the first isolation of azimuth quadrupole components from published $v_2(p_t)$ data (called elliptic flow) as spectra on transverse rapidity $y_t$ for identified pions, kaons and lambdas/protons from minimum-bias Au-Au collisions at 200 GeV. The form of the spectra on $y_t$ indicates that the three hadron species are emitted from a common boosted source with boost $Δy_{t0} \sim 0.6$. The quadrupole spectra have a Lévy form similar to the soft component of the single-particle spectrum, but with significantly reduced ($\sim 0.7\times$) slope parameters $T$. Comparison of quadrupole spectra with single-particle spectra suggests that the quadrupole component comprises a small fraction ($< 5$%) of the total hadron yield, contradicting the hydrodynamic picture of a thermalized, flowing bulk medium. The form of $v_2(p_t)$ is, within a constant factor, the product of $p'_t$ ($p_t$ in the boost frame) times the ratio of quadrupole spectrum to single-particle spectrum. That ratio in turn implies that above 0.5 GeV/c the form of $v_2(p_t)$ is dominated by the hard component of the single-particle spectrum (interpreted as due to minijets). It is therefore unlikely that so-called {\em constituent-quark scaling} attributed to $v_2$ is relevant to soft hadron production mechanisms (e.g., chemical freezeout).
description: 22 pages, 17 figures
Advanced characterisation methods for the analysis of nanoformulations and extracellular vesicles
Creators: name: Penders, Jelle
Publisher: name: Imperial College London
Year: 2019

description: Nanomedicine represents a challenging and highly multidisciplinary research field, concerned with the development and study of nanoformulations for diagnostic and/or therapeutic purposes. The nano-sized particles of interest are increasingly complex. Their translational potential has been hampered by difficulties in their thorough characterisation. On the nano scale, small variations in size and composition can have large implications for their pharmacodynamic and pharmacokinetic behaviour. More precise techniques are therefore required to address these challenges. This thesis describes novel, advanced characterisation methods designed for the detailed study of single nanoparticles and their interaction and uptake behaviour with cells. A platform technology for Single Particle Automated Raman Trapping Analysis – SPARTA - was developed, capable of non-destructive, label-free and automated comprehensive single particle analysis. With the SPARTA system, the composition, functionalisation, size and dynamic reactions on the surface can be investigated in detail, of a wide variety of nanoparticles, through their Raman spectra. A further improved, custom designed SPARTA 2.0 platform was built, optimised for the analysis of complex biological particles, such as EVs. EVs represent a high potential as biomarkers, studied here in the context of breast cancer. The SPARTA 2.0 platform was able to resolve compositional differences between non-cancerous and cancer cell-derived EVs with excellent sensitivity and specificity. This highlights the possibility for development of new minimally invasive diagnostic approaches. In addition, a new imaging strategy for investigation of the EV-cellular interaction is presented, based on 3D Focused Ion Beam – Scanning Electron Microscopy (FIB-SEM). FIB-SEM allows the generation of 3D models of the subcellular structure and visualisation of the cellular trafficking of nanoparticles. This represents a powerful new approach for investigating EV uptake. The methods developed in this thesis allow for the single particle-based analysis of a wide variety of nanoformulations and EVs, to aid in understanding their composition, applicability and cellular interactions.
The Collaboration Between Neurosurgeons and Radiologists: Historical Developments and Impacts
Creators: name: Quraishi, Muhsin
name: Farooq, Mustafa
name: Farooq, Maheen
name: Mehra, Mehul
Publisher: name: History of Radiology
Year: 2024

description: Abstract

The collaboration between neurosurgeons and radiologists has been pivotal in advancing neurosurgical techniques and improving patient outcomes over the past century. This paper traces the historical development of this interdisciplinary partnership, beginning with the introduction of X-rays by Wilhelm Röntgen in 1895. Early neurosurgeons quickly adopted X-rays for detecting skull fractures and foreign bodies, despite its limitations in providing two-dimensional images. The collaboration deepened in the 1920s with pneumoencephalography, enhancing the accuracy of brain tumor localization. The development of computed tomography (CT) in 1972 marked a turning point, as neurosurgeons were now able to use detailed cross-sectional images of the brain to plan surgeries with unprecedented precision. Magnetic resonance imaging (MRI) in the 1980s and functional MRI (fMRI) in the 1990s further revolutionized the field by allowing for highly accurate visualization of brain structures and functional areas, critical for complex neurosurgical procedures. More recently, intraoperative MRI (iMRI) and real-time imaging technologies have enabled neurosurgeons to adjust their interventions during surgery, further improving surgical outcomes. The advent of artificial intelligence (AI) and augmented reality (AR) promises to push the boundaries of neurosurgical planning and execution even further. This historical review highlights the integral role that radiology has played in neurosurgical advancements and underscores the importance of continued collaboration between neurosurgeons and radiologists in driving future innovations.