97 research outputs found
An investigation of the secondary organic aerosol formation and volatility in mixtures of anthropogenic and biogenic precursors using smog chamber experiments
Full text linkSubmicron particle number doses in the human respiratory tract: implications for urban traffic and background environments
No full textThe deposition of ambient submicron particles in the different parts of the human respiratory tract (HRT) was, for the first time, estimated for males and females from different age classes (children-adults-seniors) of urban population in the city of Thessaloniki, northern Greece, during the cold and the warm period of the year. Outdoor daily and hourly particle number doses in the different regions of the HRT, i.e., the extra-thoracic (ET), tracheobronchial (TB), and the acinar (AC) regions, were calculated by employing the Multiple-Path Particle Dosimetry (MPPD) model. Because of the absence of information being available for the hygroscopic properties of particles, three different particle hygroscopicity scenarios were considered: (i) non-hygroscopic (i.e., raw model estimations), (ii) nearly hydrophobic, and (iii) hygroscopic particles. When hygroscopic properties were considered, we found a remarkable reduction (up to ~ 55%) in the estimated total particle number doses in comparison to the non-hygroscopic particle scenario. Furthermore, we found that the size distribution pattern of the particle doses within the different parts of the HRT was strongly affected by particles’ hygroscopic properties with the non-hygroscopic particle scenario significantly overestimating the particle doses in the sub-100-nm range, while underestimating the doses of larger particles. On the contrary, the deposition density appeared to be negligibly affected by the particles’ hygroscopic properties, implying the existence of a possible threshold in the number of particles deposited per airway surface area. Similarly, the lobar particle number deposition fraction was unaffected by the hygroscopic properties of particles, as well as the ambient particle size distribution and the individuals’ physiological parameters. The total particle number deposition doses estimated here are within the range of the corresponding values reported for other urban environments. It is hoped that our findings could contribute to better understanding of submicron particle exposure and add to the development of more sufficient methods to evaluate the related health impacts
Structural Optimisation of Permanent Magnet Direct Drive Generators for 5MW Wind Turbines
Full text linkThis thesis has been submitted in fulfilment of the requirements for a postgraduate degree (e.g. PhD, MPhil, DClinPsychol) at the University of Edinburgh. Please note the following terms and conditions of use: • This work is protected by copyright and other intellectual property rights, which are retained by the thesis author, unless otherwise stated. • A copy can be downloaded for personal non-commercial research or study, without prior permission or charge. • This thesis cannot be reproduced or quoted extensively from without first obtaining permission in writing from the author. • The content must not be changed in any way or sold commercially in any format or medium without the formal permission of the author. • When referring to this work, full bibliographic details including the author, title, awarding institution and date of the thesis must be given
New insights on humic-like substances associated with wintertime urban aerosols from central and southern Europe: Size-resolved chemical characterization and optical properties
No full textAlthough Humic-LIke Substances (HULIS) are important contributors to the mass of organic aerosol in airborne particulate matter (PM), little is known about their chemical composition, while, their size-resolved optical properties have not been studied yet. Here, HULIS fractions were isolated from size-resolved aerosol samples (≤0.49, 0.49–0.95, 0.95–3 and 3–10 μm) collected in urban and suburban environments of four European cities during wintertime. The bulk (i.e., sum of all size fractions) concentration of HULIS ranged between 1.29 and 2.80 μg m−3 across sites with highest values in the ≤0.49 μm particle size fraction. The contribution of the carbon mass of HULIS (HULIS-C) to the water-soluble organic carbon content (WSOC) of PM was 32–43%, which is typical for urban sites affected by biomass burning. The Mass Absorption Efficiency (MAE), which characterizes the efficiency of absorbing solar energy per carbon mass of HULIS decreased with particle size, suggesting that the finest size fractions contain more light-absorbing chromophores, which could affect the light-absorbing ability of organic aerosols. The good correlation of HULIS with effective biomass tracers such as K+, as well as with secondary inorganic aerosol components, proposed that HULIS had both primary (i.e., biomass burning) and secondary sources. The Fourier Transfer Infrared coupled to Attenuation Total Reflectance (FTIR-ATR) spectra demonstrated prevalence of aromatic over carboxylic functional groups in most HULIS fractions, indicating contribution from coal combustion emissions in addition to fresh biomass burning aerosol. The new findings add to better understanding the sources and chemical structure of HULIS in urban and suburban environments
Temporal analysis of the least energetic events in pulsar data from observations with the high energy stereoscopic system
Full text linkIt has been more than 60 years since astronomers turned their attention towards the 7֊ray window (> 100 TeV). Nowadays, 7֊ray astronomy has won its place as a separate branch of astronomy in its own right. The present thesis introduces the reader to 7-ray observations in the 〜 100 GeV-100 TeV energy window, but focuses, in particular, on the efforts to describe and detect the pulsed, Very High-Energy (VHE) 7-ray emission from pulsars. Pulsars are highly magnetised {B 〜 101շ G) ， rapidly rotating (P ~ 10—2 s) neutron stars. Periodic radio emission from pulsars has been detected in more than 1,500 cases, in contrast to their 7-ray signature which has been confirmed for only six of them and only up to a few GeV. There are many models in existence which attempt to reproduce the observed pulsed profiles and energy spectra in high energies (optical, X and ๆ rays). Nevertheless, two classes of models are the most popular: the Polar Cap and the Outer Gap models. Both predict spectral cut-offs at tens of GeV, which are consistent with previous upper limits in the VHE range. The six most energetic pulsars have been detected with the EGRET (Energetic Gamma Ray Experiment Telescope) instrument on-board the с GRO (Compton Gamma Ray Observatory) satellite. Probing the universe at higher energies requires a different detection technique. The Imaging Atmospheric Technique (lACT) exploits the Earth's atmosphere with the use of large, ground-based reflectors that are very sensitive to Cherenkov light (300-600 nm). The latter is produced during electromagnetic particle cascades, triggered by the interaction of VHE 7 rays with the top atmospheric layers. So far there has not been a confirmed pulsar detection using Cherenkov astronomy. The High Energy Stereoscopic System (H.E.S.S.) in Namibia is an array of four telescopes, which is sensitive above 100 GeV. H.E.S.S. uses the lACT to reject the lO3 times more abundant cosmic-ray events that suppress the 7-ray signal. The system is capable of stereoscopic observations of the same source with all four telescopes, which further eliminates background events. Despite the fact that imaging with H.E.S.S. is not effective below 100 GeV, lower energy events can still be recorded, along with a large portion of the background. The present thesis deals with the least energetic events (< 100 ĢeV) detectable with H.E.ร.ร., where pulsar 7-ray emission is likely to be present. A very sensitive temporal analysis has been performed in order to identify the potentially periodic events in the large background. The necessary procedures and parameters of the analysis are described in detail, prior to the results. The author has analysed data from two 7-ray pulsars, the Crab and PSR B1706-44, which were seen with EGRET up to ~ 20 GeV, as well as the binary radio pulsar PSR B1259-63, which has not been detected at high energies (> 1 eV). The data were optimised for the lowest energies, and the lowest energy threshold achieved was 75 GeV (in the case of PSR B1706-44). In all cases studied, the author coded and applied a number of periodicity tests that check for significant deviations from random noise. The resulting probabilities were not significantly low to support signal presence. Based on the background levels in the data sets, the author derived upper limits on the integral and differential flux. These upper limits were consistent with the Polar Cap and Outer Gap scenarios, within statistical errors, but constrain the alternative model of a spectrum with a simple exponential cut-off in the case of PSR B1706—44. Despite the lack of detection, these results represent the lowest energies explored with H.E.S.S.， yet
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Impact of water uptake and mixing state on submicron particle deposition in the human respiratory tract (HRT) based on explicit hygroscopicity measurements at HRT-like conditions
Full text linkParticle hygroscopicity plays a key role in determining the particle deposition in the human respiratory tract (HRT). In this study, the effects of hygroscopicity and mixing state on regional and total deposition doses on the basis of the particle number concentration for children, adults, and the elderly were quantified using the Multiple-Path Particle Dosimetry model, based on the size-resolved particle hygroscopicity measurements at HRT-like conditions (relative humidity = 98 %) performed in the North China Plain. The measured particle population with an external mixing state was dominated by hygroscopic particles (number fraction = (91.5 ± 5.7) %, mean ± standard deviation (SD); the same below). Particle hygroscopic growth in the HRT led to a reduction by around 24 % in the total doses of submicron particles for all age groups. Such a reduction was mainly caused by the growth of hygroscopic particles and was more pronounced in the pulmonary and tracheobronchial regions. Regardless of hygroscopicity, the elderly group of people had the highest total dose among three age groups, while children received the maximum total deposition rate. With 270 nm in diameter as the boundary, the total deposition doses of particles smaller than this diameter were overestimated, and those of larger particles were underestimated, assuming no particle hygroscopic growth in the HRT. From the perspective of the daily variation, the deposition rates of hygroscopic particles with an average of (2.88 ± 0.81) × 109 particles h-1 during the daytime were larger than those at night ((2.32 ± 0.24) × 109 particles h-1). On the contrary, hydrophobic particles interpreted as freshly emitted soot and primary organic aerosols exhibited higher deposition rates at nighttime ((3.39 ± 1.34) × 108 particles h-1) than those in the day ((2.58 ± 0.76) × 108 particles h-1). The traffic emissions during the rush hours enhanced the deposition rate of hydrophobic particles. This work provides a more explicit assessment of the impact of hygroscopicity and mixing state on the deposition pattern of submicron particles in the HRT. Copyright
Author Response: Safety and Efficacy of Dual Antiplatelet Pretreatment in Patients With Ischemic Stroke Treated With IV Thrombolysis: A Systematic Review and Meta-analysis
No full textChemical composition of secondary organic aerosol particles formed from mixtures of anthropogenic and biogenic precursors
Full text linkA series of experiments was designed and conducted in the Manchester Aerosol Chamber (MAC) to study the photo-oxidation of single and mixed biogenic (isoprene and α-pinene) and anthropogenic (o-cresol) precursors in the presence of NOx and ammonium sulfate seed particles. Several online techniques (HR-ToF-AMS, semi-continuous GC-MS, NOx and O3 analyser) were coupled to the MAC to monitor the gas and particle mass concentrations. Secondary organic aerosol (SOA) particles were collected onto a quartz-fibre filter at the end of each experiment and analysed using liquid chromatography–ultrahigh-resolution mass spectrometry (LC-Orbitrap MS). The SOA particle chemical composition in single and mixed precursor systems was investigated using non-targeted accurate mass analysis of measurements in both negative and positive ionization modes, significantly reducing data complexity and analysis time, thereby providing a more complete assessment of the chemical composition. This non-targeted analysis is not widely used in environmental science and has never been previously used in atmospheric simulation chamber studies. Products from α-pinene were found to dominate the binary mixed α-pinene–isoprene system in terms of signal contributed and the number of particle components detected. Isoprene photo-oxidation was found to generate negligible SOA particle mass under the investigated experimental conditions, and isoprene-derived products made a negligible contribution to particle composition in the α-pinene–isoprene system. No compounds uniquely found in this system sufficiently contributed to be reliably considered a tracer compound for the mixture. Methyl-nitrocatechol isomers (C7H7NO4) and methyl-nitrophenol (C7H7NO3) from o-cresol oxidation made dominant contributions to the SOA particle composition in both the o-cresol–isoprene and o-cresol–α-pinene binary systems in negative ionization mode. In contrast, interactions in the oxidation mechanisms led to the formation of compounds uniquely found in the mixed o-cresol-containing binary systems in positive ionization mode. C9H11NO and C8H8O10 made large signal contributions in the o-cresol–isoprene binary system. The SOA molecular composition in the o-cresol–α-pinene system in positive ionization mode is mainly driven by the high-molecular-weight compounds (e.g. C20H31NO4 and C20H30O3) uniquely found in the mixture. The SOA particle chemical composition formed in the ternary system is more complex. The molecular composition and signal abundance are both markedly similar to those in the single α-pinene system in positive ionization mode, with major contributions from o-cresol products in negative ionization mode
Η εφαρμογή συστημάτων ολικής ποιότητας σε ασταθή μακρο-περιβάλλοντα
No full textThis research is dealing with the implementation of Total Quality Management tools in an unstable macro-environment, by using a special TQM tool, the Common Assessment Framework and its implementation in the Greek Public Sector, which faced unusual circumstances over the last 8 years, due to the Greek debt crisis. As many authors indicated in the past, literature has everything someone needs to know about TQM implementations, but in most of the cases the reality does not match with the original plan, because there are internal organisational factors that affect the TQM implementation process. Additionally, according to PESTEL analysis, external macro-environmental factors have an impact on an organisation, and its processes. These factors are; Political, Economic, Sociological, Technological, Environmental and Legal. Hence there are external organisational factors that affect the TQM implementation process. On the other hand, in times of fiscal crisis and unstable economic macro-environment the adoption of quality principles by organisations may improve their ability to deal with uncertainty and offer citizens – customers quality services. Nevertheless, lack of resources and support in times of financial crisis may affect corporate culture and cause problems in TQM successful implementation. Additionally, uncontrollable factors in the external environment have an adverse impact on implementation process and cause strategy implementation problems. Having the above in mind, the author combined TQM implementation theory with PESTEL analysis, in order to identify the critical factors for successful implementation of TQM tools, especially in times of an unstable macro-environment; finding out that an important area that needs attention is the attributes of the external environment where the organization operates, in order for the TQM implementation to be effective. Hence, this research contributes to the body of knowledge of TQM theory by exploring how the external environmental factors affect its implementation processes, by using the PESTEL analysis.Η παρούσα έρευνα ασχολείται με την εφαρμογή εργαλείων Ολικής Διαχείρισης Ποιότητας σε ένα ασταθές μακρο-περιβάλλον, με τη χρήση ενός ειδικού εργαλείου TQM, του Κοινού Πλαισίου Αξιολόγησης και την εφαρμογή του στον Ελληνικό Δημόσιο Τομέα, ο οποίος αντιμετώπισε ασυνήθιστες συνθήκες τα τελευταία 8 χρόνια, λόγω στην ελληνική κρίση χρέους.Όπως ανέφεραν πολλοί συγγραφείς στο παρελθόν, η βιβλιογραφία έχει όλα όσα χρειάζεται να γνωρίζει κάποιος για τις εφαρμογές TQM, αλλά στις περισσότερες περιπτώσεις η πραγματικότητα δεν ταιριάζει με το αρχικό σχέδιο, επειδή υπάρχουν εσωτερικοί οργανωτικοί παράγοντες που επηρεάζουν τη διαδικασία υλοποίησης TQM. Επιπλέον, σύμφωνα με την ανάλυση PESTEL, οι εξωτερικοί μακρο-περιβαλλοντικοί παράγοντες έχουν αντίκτυπο σε έναν οργανισμό και στις διαδικασίες του. Αυτοί οι παράγοντες είναι: Πολιτικά, Οικονομικά, Κοινωνιολογικά, Τεχνολογικά, Περιβαλλοντικά και Νομικά θέματα. Ως εκ τούτου, υπάρχουν εξωτερικοί οργανωτικοί παράγοντες που επηρεάζουν τη διαδικασία εφαρμογής της TQM. Από την άλλη πλευρά, σε περιόδους δημοσιονομικής κρίσης και ασταθούς οικονομικού μακροπεριβάλλοντος, η υιοθέτηση αρχών ποιότητας από τους οργανισμούς μπορεί να βελτιώσει την ικανότητά τους να αντιμετωπίζουν την αβεβαιότητα και να προσφέρουν στους πολίτες – πελάτες ποιοτικές υπηρεσίες. Ωστόσο, η έλλειψη πόρων και υποστήριξης σε περιόδους οικονομικής κρίσης μπορεί να επηρεάσει την εταιρική κουλτούρα και να προκαλέσει προβλήματα στην επιτυχή εφαρμογή της TQM. Επιπλέον, ανεξέλεγκτοι παράγοντες στο εξωτερικό περιβάλλον έχουν αρνητικό αντίκτυπο στη διαδικασία υλοποίησης και προκαλούν προβλήματα στην υλοποίηση της στρατηγικής.Έχοντας υπόψη τα παραπάνω, ο συγγραφέας συνδύασε τη θεωρία υλοποίησης TQM με την ανάλυση PESTEL, προκειμένου να εντοπίσει τους κρίσιμους παράγοντες για την επιτυχή εφαρμογή των εργαλείων TQM, ειδικά σε περιόδους ασταθούς μακρο-περιβάλλοντος. Διαπιστώνοντας ότι ένας σημαντικός τομέας που χρήζει προσοχής είναι τα χαρακτηριστικά του εξωτερικού περιβάλλοντος όπου δραστηριοποιείται ο οργανισμός, προκειμένου η εφαρμογή της TQM να είναι αποτελεσματική. Ως εκ τούτου, αυτή η έρευνα συμβάλλει στο σύνολο των γνώσεων της θεωρίας TQM διερευνώντας πώς οι εξωτερικοί παράγοντες επηρεάζουν τις διαδικασίες εφαρμογής της, χρησιμοποιώντας την ανάλυση PESTEL
The contribution of George Fragoudis to the social and political life in Greece
No full textGeorgios Fragoudis was one of the most interesting public figures of Greek public life. As a very young student of Law he began working as a journalist in leading Greek newspapers and later as a publisher and he published articles on almost every political and social issue of his time, from urban planning to constitutional revision and from the problems of the Greek diaspora to the teaching of the Greek language. He was an admirer of Venizelos but he was also one of his most severe critics. He was author of many books, a man which stands out the book Cypris, a well-documented presentation of the history, life and customs of his native island of Cyprus. In 1901 he organised the Exhibition of Cyprus in Athens, a much-admired event, which presented the culture and the art of Cyprus to the Greek audience. Since 1910 he concived the idea that the political problems of Greece were due to the lack of education in the field of political and social sciences. He devoted ten years of his life to the founding of the University of Political Sciences, which he considered as the main achievement of his life. He introduced the teaching of political and social sciences in Greece.Η ανά χείρας διδακτορική διατριβή παρουσιάζει το έργο και την ζωή του Γεωργίου Φραγκούδη, ο οποίος υπήρξε ο ένας εκ των δύο ιδρυτών της Παντείου Ανωτάτης Σχολής Πολιτικών Επιστημών, ενός άνδρα με πολλές ιδιότητες και ιδιαιτέρως ενδιαφέρουσα προσωπικότητα. Ο Κύπριος Γεώργιος Φραγκούδης ήταν δημοσιολόγος, δικηγόρος, συγγραφέας ταξιδιωτικών και ιστορικών βιβλίων, πολιτικών δοκιμίων και μεταφραστής, συντάκτης κυπριακού συντάγματος, δημοσιογράφος και εκδότης εφημερίδων, διοργανωτής της Πρώτης Εκθέσεως για την Κύπρο στην Αθήνα και των Πανελληνίων Αγώνων, ρήτορας και πολιτικός, μέλος της Δ΄ Συντακτικής Συνέλευσης της Ελλάδος και μέλος της συντακτικής επιτροπής του Ελληνικού Συντάγματος του 1925 και τέλος ιδρυτής της Παντείου Ανωτάτης Σχολής Πολιτικών Επιστημών, του κυκνείου άσματος, με το οποίο πραγματοποίησε το όνειρό του να συμβάλει στην εξύψωση του επιπέδου της πολιτικής ζωής στην Ελλάδα. Και ακόμη πρωτεργάτης του ενωτικού κινήματος στην Κύπρο και αργότερα υποστηρικτής της αυτονομίας, υποστηρικτής του Βενιζέλου στο κίνημα της Θεσσαλονίκης και αυστηρός κριτής του σε όλες του τις πολιτικές επιλογές, με ισχυρό ένστικτο επιβίωσης και απίστευτη προσαρμοστικότητα, επινοητικός και ακούραστος, γεννημένος συγγραφέας, περιηγητής και άνθρωπος της δράσης, ανυποχώρητος στις απόψεις του χωρίς να υπολογίζει τις συνέπειες, ο Φραγκούδης υπήρξε μια προσωπικότητα που κατάφερε χωρίς υλική βάση να παίξει ένα σημαντικό ρόλο στην δημόσια ζωή της Ελλάδας και τελικώς να δημιουργήσει ένα ανώτατο εκπαιδευτικό ίδρυμα, το οποίο εισήγαγε την μελέτη των πολιτικών και κοινωνικών επιστημών στην Ελλάδα και απετέλεσε το βήμα πολλών σημαντικών επιστημόνων της εποχής του Μεσοπολέμου. Η ίδρυση της Παντείου Ανωτάτης Σχολής προσέφερε ένα στοργικό πλαίσιο σε επιστήμονες, οι οποίοι δεν θα είχαν βρει πουθενά αλλού επιστημονική στέγη και θα είχαν μείνει στο εξωτερικό, έδωσε επιστημονικά εφόδια σε μεγάλο αριθμό Ελλήνων και Ελληνίδων και προσέφερε ανθρώπινο κατηρτισμένο δυναμικό σε όλους τους κλάδους της δημόσιας διοίκησης από το 1930 έως σήμερα
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