Thesis (Ph. D.)--Massachusetts Institute of Technology and Woods Hole Oceanographic Institution Joint Program in Oceanography/Applied Ocean Science and Engineering, 1997. / "September 1997." "Funding was provided by National Science Foundation Grant OCE-9201286, National Science Foundation Graduate Fellowship Program, and the JOI/USSAC Ocean Drilling Graduate Fellowship Program." Includes bibliographical references (p. 152-153).

Τα τελευταια χρόνια ειμαστε μαρτυρες ενός εντυπωσιακού παραδόξου στο χώρο της τεχνολογίας. Ενώ όλη η ανθρωπότητα αναζητά το κάτι παραπάνω σε υπολογιστική ισχύ, σε χώρο αποθήκευσης και σε ταχύτητα, μικρές αυτόνομες συσκευές έρχονται να κατακτήσουν όλο και περισσότερους τομείς της καθημερινότητάς μας. Μονάδες με την ικανότητα της επεξεργασίας και της αποθήκευσης δεδομένων, της αίσθησης του περιβάλλοντος αλλά και της επικοινωνίας μεταξύ τους, ενσωματώνονται σχεδόν σε όλους τους τομείς δραστηριοποίησης του ανθρώπου. Ο τρόπος αυτό-οργάνωσης αυτών των κόμβων - μονάδων στα πλαίσια μεγάλων ασύρματων δικτύων αισθητήρων, και η συλλογή δεδομένων από μια ευρεία περιοχή, τους δίνει τη δυνατότητα λήψης αποφάσεων, πολλές φορές κρίσιμων, ανάλογα με τις επικρατούμενες συνθήκες. Τα παραπάνω χαρακτηριστικά των δομικών στοιχείων των ασυρμάτων δικτύων αισθητήρων, σε συνδυασμό με τις υπηρεσίες της υψηλής και καθιερωμένης τεχνολογίας του συστήματος GPS (Global Positioning System) μπορούν να δημιουργήσουν έναν εκρηκτικό συνδυασμό και ερευνητικές ιδέες για ανάπτυξη αστικών εφαρμογών αυτοματισμού, στο πλαίσιο των λεγόμενων «έξυπνων πόλεων». Μέσα σε ένα απέραντο δίκτυο ασυρμάτων αισθητήρων, αποτελούμενο από χιλιάδες οντότητες, η ικανότητα του κάθε κόμβου να εντοπίζει την θέση του και να την μοιράζεται με τους υπόλοιπους, κερδίζει ολοένα και περισσότερο έδαφος ειδικά σε θέματα δρομολόγησης. Η χρήση της τεχνολογίας GPS από έναν κόμβο, αντικείμενο που μελετάμε στη παρούσα εργασία, μπορεί να οδηγήσει από την επιτυχή εφαρμογή του Geographical Routing σε ένα WSN, μέχρι την υλοποίηση απαιτητικών εφαρμογών για αντιγραφή κίνησης αλλά και δημιουργίας «έξυπνων αυτοκινητόδρομων» μέσα στους οποίους θα γίνεται αυτόματη πλοήγηση των κινητών υπό την επίβλεψη ενός μεγάλου WSN με κόμβους που συνεργάζονται με το σύστημα δορυφορικού εντοπισμού θέσης αλλά και μεταξύ τους. Όπως γίνεται άμεσα αντιληπτό, η παρούσα εργασία, που πραγματεύεται την σωστή συνεργασία και επικοινωνία ενός δικτύου ασυρμάτων αισθητήρων με την τεχνολογία GPS για την ιχνηλάτηση της πορείας ενός κινητού, μπορεί να δώσει μελλοντική τροφή για ενασχόληση σε πολλαπλά ερευνητικά επίπεδα. Η εργασία μας χωρίστηκε σε τρείς θεματικές ενότητες. Η πρώτη αφορά τον τομέα του WSN και του προγραμματισμού των κόμβων, για επικοινωνία με τους δορυφόρους, με τον υπολογιστή αλλά και μεταξύ τους, με τις απαραίτητες λειτουργικές εφαρμογές που κληθήκαμε να υλοποιήσουμε. Η δεύτερη αναφέρεται στην εργασία μας από την πλευρά του υπολογιστή, που λειτουργεί σαν συλλέκτης των δεδομένων του δικτύου, και τη σύνδεση του συστήματός μας με την πρότυπη εφαρμογή Google EarthTM για απεικόνιση σε πραγματικό χρόνο της τροχιάς που ακολουθεί ένα κινητό. Η τρίτη ενότητα περιλαμβάνει εκτέλεση πειραμάτων χρήσης του συστήματος που σχεδιάσαμε και παράθεση οπτικοποιημένων αποτελεσμάτων, για την εύκολη εξαγωγή χρήσιμων συμπερασμάτων όσον αφορά στη λειτουργικότητά του. / The last few years we witness a striking paradox in the field of technology. While all humanity is seeking for more computing power, more storage capabilities and more proccessing speed, small autonomous devices have appeared to occupy more and more areas of our lives in the daily routine. Units with the capabilities of data proccessing, data storage, enviromental sensing and communication with each other, are incorporated in almost all areas of human activity. The way in which these nodes are self-organized into large Wireless Sensor Networks and their ability to collect data from a wide area, enables them in taking decisions, critical ones sometimes, according to the prevailing conditions. The above characteristics of the components of wireless sensor networks, combined with the services of the established and standard technology of the GPS (Global Positioning System) can create ideas for research and development of urban applications of automation in the so-called “smart cities”. In a vast network of wireless sensors, consisting of thousands of entities, the ability of each node to detect its position and share it with others, is gaining more and more ground especially in routing topics. The use of GPS technology from a node, which is one of the subjects we study in this thesis, could lead from the successful implementation of the Geographical Routing, to the implementation of more demanding applications for motion replication but also to creating “smart highways” through which mobiles will execute an automatic navigation, supervised by a large WSN consisting of nodes cooperating with the satellite positioning system and with each other. As is readily apparent, the present thesis which is dealing with the good cooperation and communication of a wireless sensor network with the GPS technology in order to trace the path of a mobile, can provide room for future involvement in multiple levels of research. Our work was divided into three thematic sections. The first concerns the field of WSN and node programming so that they can be able to communicate with satellites, with the computer and with each other, by installing them with the necessary functional applications that we had to implement. The second section refers to our work on the computer side, which acts as a network data collector, and the link of our system with the standard Google EarthTM application to display the path of a mobile in real – time. The third section includes conducting experiments using the system we designed. The results are visualised and listed for an easy extraction of usefull conclusions regarding the functionality of our system.

Introduction: Policing is a public health issue. The police often encounter vulnerable populations. Police officers have wide discretionary powers, which could impact on how they support vulnerable populations. In encountering vulnerable populations the police officers are required to be professional; maintaining mental health in the face of challenges is part of professionalism. Their encounters with vulnerable populations might influence their mental health which in turn might influence the way they use their discretion when making decisions. Background/context: Sweden receives more unaccompanied, asylum-seeking refugee children than any other country in Europe. The number of asylum applications for such children increased from 400 in 2004 to 7000 in 2014 to over 35,000 in 2015. These children come to Sweden and apply for asylum without being under the care of their parents or other legal guardian. Some are denied asylum. If they do not return to their country of origin voluntarily the police are responsible for their deportation. The Swedish government wants an increasing number of deportations and wants them carried out with dignity. This thesis is about the police officers’ perceptions of how to interpret the seemingly contradictory demands for more deportations, that is, efficiency; and concerns for human rights during the deportation process, that is, dignity. This is conceptualized using three theoretical frameworks: a) street-level bureaucracy, b) job demand-control-social support model and c) coping. These theoretical frameworks indicate the complexity of the issue and function as constructions by means of which understanding can be brought to the police officers’ perceptions of deportation work involving unaccompanied, asylum-seeking refugee children and how such work is associated to their mental health. Aim: The current research aims to investigate and analyse Swedish police officers’ mental health in the context of deportations of unaccompanied, asylum-seeking refugee children. Methods: This thesis uses both qualitative and quantitative methodology. The qualitative approach comprised interviews conducted to achieve a deeper understanding of the phenomenon of police officers’ perceptions of deportations of unaccompanied, asylum-seeking refugee children. The quantitative method involved the use of validated questionnaires to investigate the association between police officers’ mental health and psychosocial job characteristics and coping. This approach made it possible to study a complex issue in a complex environment and to present relevant recommendations. A total of 14 border police officers were interviewed and 714 police officers responded to a survey. Results: The police officers utilize their wide discretionary powers and perceive that they are doing what is best in the situation, trying to listen to the child and to be aware of the child’s needs. Police officers with experience of deportations of unaccompanied, asylum-seeking refugee children were not found to have poorer mental health than police officers with no such experience. Furthermore, high job demand, low decision latitude, low levels of work-related social support, shift work and being single are associated with poor mental health. Coping moderates the association between mental health and the experience of carrying out deportations of unaccompanied, asylum-seeking, refugee children, and the police officers seem to utilize both emotional and problem-solving coping during the same complex deportation process. Implications / conclusions: The general conclusion reached in this thesis is that if police officers are subject to reasonable demands, have high decision latitude, access to work-related social support, and utilize adaptable coping, the deportation work does not seem to affect their mental health. When police officers meet vulnerable people, they utilize their discretionary powers to deal with seemingly contradictory demands, that is, efficiency and dignity. The executive role in the deportations of unaccompanied, asylum-seeking refugee children and the awareness of dealing with a child threatened with deportation might give rise to activation of a sense of protection, safety and security. Discretion might make it possible to act on this sense of protection, safety and security and to combine efficiency and dignity. Further studies, which integrate cognitive and emotional discretion with coping, need to be undertaken. / Introduktion: Polisarbete är i mångt och mycket en folkhälsofråga, något som inte minst blir tydligt i polisers möte med utsatta människor. Poliser har ett stort handlingsutrymme, vilket kan påverka hur de bemöter utsatta människor. I mötet med dessa människor behöver poliserna vara professionella; att ta hand om sin psykiska hälsa när man möts av utmaningar är en del av professionalismen. Att möta utsatta människor kan påverka polisernas psykiska hälsa, som i sin tur kan påverka hur de använder sitt handlingsutrymme när de fattar beslut. Bakgrund: Sverige tar emot fler ensamkommande asylsökande flyktingbarn än något annat land i Europa. Antalet asylansökningar för sådana barn ökade från 400 år 2004 till 7000 år 2014 till över 35 000 år 2015. Dessa barn kommer till Sverige och ansöker om asyl utan sina föräldrar eller annan vårdnadshavare. Somliga av dem nekas asyl. Om de inte återvänder till sitt ursprungsland frivilligt är polisen ansvariga för utvisningen. Den svenska regeringen kräver ett ökande antal verkställigheter av av- och utvisningar samt fastlår att verkställigheterna ska genomföras med respekt för människors värdighet. Denna avhandling handlar om polisers uppfattningar och tolkningar av de till synes motsägelsefulla kraven på att verkställa fler av- och utvisningar, det vill säga effektivitet; och hur man hanterar de mänskliga rättigheterna under utvisningsprocessen, det vill säga värdighet. Detta beskrivs och analyseras med hjälp av tre teoretiska ramverk: a) gräsrotsbyråkrati, b) jobb-krav-kontroll-socialt stödmodellen och c) coping. Dessa teoretiska ramverk visar på arbetsuppgiftens komplexitet och fungerar som utgångspunkt för att skapa förståelse för polisernas uppfattningar av arbetet med att verkställa av- och utvisningar av ensamkommande asylsökande flyktingbarn och hur sådant arbete är associerat med polisernas psykiska hälsa. Syfte: Denna avhandling syftar till att undersöka och analysera svenska polisers psykiska hälsa i relation till av- och utvisningar av ensamkommande asylsökande flyktingbarn. Metod: Både kvalitativ och kvantitativ metod användes i denna avhandling. Det kvalitativa tillvägagångssättet innefattade intervjuer för att uppnå en djupare förståelse för hur poliser uppfattar av- och utvisningar av ensamkommande asylsökande flyktingbarn. Den kvantitativa metoden innebar tillämpning av validerade frågeformulär för att undersöka sambandet mellan polisernas psykiska hälsa och psykosociala jobbkarakteristika samt coping. Detta tillvägagångssätt gjorde det möjligt att studera en komplex fråga i en komplex miljö och att presentera relevanta rekommendationer. Totalt intervjuades 14 gränspoliser och 714 poliser svarade på en enkätundersökning. Resultat: Resultatet visar att poliserna utnyttjar sitt stora handlingsutrymme och uppfattar att de gör det som är bäst i situationen, att de försöker lyssna på barnet och vara medvetna om barnets behov. Poliser med erfarenhet av av- och utvisningar av ensamkommande asylsökande flyktingbarn har inte visat sig ha en sämre psykisk hälsa än poliser utan sådan erfarenhet. Vidare är höga krav och lågt beslutsutrymme på arbetet, låga nivåer av arbetsrelaterat socialt stöd, skiftarbete och singelliv associerat med dålig psykisk hälsa. Coping mildrar effekten på den psykiska hälsan hos de som har erfarenhet av att utföra av- och utvisningar av ensamkommande asylsökande flyktingbarn. Poliserna verkar utnyttja både emotionell och problemlösande coping under en och samma komplexa utvisningsprocess. Slutsats: Den viktigaste slutsatsen i denna avhandling är att om poliser utsätts för rimliga krav, har stort beslutsutrymme, tillgång till arbetsrelaterat socialt stöd och använder sig av anpassningsbar coping, verkar det som att arbetet med av- och utvisningar inte påverkar deras psykiska hälsa. När poliser möter utsatta människor utnyttjar de sitt handlingsutrymme för att hantera de till synes motsägelsefulla kraven, det vill säga effektivitet och värdighet. Den verkställande rollen i av- och utvisningar av ensamkommande asylsökande flyktingbarn och medvetenheten om att hantera ett barn som hotas av utvisning kan ge upphov till en aktivering av känslan att ge skydd, trygghet och säkerhet. Handlingsutrymmet kan göra det möjligt att agera på denna känsla av skydd, trygghet och säkerhet samt att kunna kombinera effektivitet och värdighet. Ytterligare studier, som integrerar kognitivt och känslomässigt handlingsutrymme med coping, behöver emellertid genomföras.

Les transformations du monde du travail, dues à la mondialisation, se font principalement au profit de l’efficacité et l’efficience des entreprises. Ces changements, touchant aussi l’organisation du travail, ne sont pas sans effets sur la santé des travailleurs. Cette étude traite principalement de l’effet des horaires atypiques sur la santé mentale des travailleurs. Elle a pour objectifs 1) d’étudier l’association entre l’horaire atypique et les problèmes de santé mentale chez les travailleurs ; 2) d’explorer l’effet du conflit travail-famille, des demandes psychologiques et de l’autorité décisionnelle sur la santé mentale des travailleurs. Cette étude est basée sur un échantillon de 2 162 participants de l’enquête SALVEO, qui est une des plus importantes études réalisées sur la santé mentale et le travail au Canada. Préalablement, des analyses descriptives ont été effectués afin de dresser le portrait de la population à l’étude et de comparer la prévalence des problèmes de santé mentale chez les travailleurs. Afin de tester les hypothèses, des analyses de corrélation bivariée et de régression logistique ont été réalisées. Les résultats nous ont montré que les horaires atypiques n’ont pas d’association directe sur la santé mentale des travailleurs. Cependant, l’horaire atypique est associé à des problèmes de santé mentale. Le conflit travail-famille et les demandes psychologiques tendent à augmenter le risque de développer des problèmes de santé mentale, et inversement pour l’autorité décisionnelle. / The changes in the world of work due to globalization are mainly for the benefit of the effectiveness and efficiency of enterprises. These changes, which also affect the work organization, are not without effects on the health of workers. This thesis focuses on the effect of non-standard work schedules on the mental health of workers. Its objectives are 1) to study the association between non-standard schedules and mental health problems among workers; and 2) to explore the effect of work-family conflict, psychological demands, and decision latitude on workers' mental health. This study is based on a sample of 2,162 participants from the SALVEO survey, which is one of the most important mental health studies conducted in Canada. Preliminary, descriptive analyses were conducted in order to draw up a portrait of the study population and compare the prevalence of mental health problems among workers. In order to refute or confirm the hypotheses put forward, bivariate correlation and logistic regression analyses were carried out. All analyses were performed using version 25 of the SPSS software. The results showed us that non-standard schedules have no direct effect on the mental health of workers. However, people working non-standard schedules are at greater risk of developing mental health problems compared to those working standard schedules. Work-family conflict and psychological demands tend to increase the risk of developing mental health problems, while decision-making latitude has the opposite effect.

As average global temperatures rise, cool-season C3 turfgrasses, such as the most commonly grown Kentucky bluegrass (Poa pratensis L.; KBG), struggle to tolerate extreme summer heat and increase their water consumption. Hybrid Bermudagrass (Cynodon dactylon [L.] Pers. × Cynodon transvaalensis Burtt Davy; HBG) is a warm-season C4 grass that may be increasingly suited for northern ecosystems traditionally classified as transition or cool-season climate zones. Glasshouse and field studies were conducted to compare HBG and KBG water use. The objective of the glasshouse study was to evaluate plant health and growth for two HBG cultivars (‘DT-1’ and ‘NorthBridge’) compared to a blend of KBG cultivars in all combinations of deficit, moderate, and high irrigation at optimum or short mowing height. The study was conducted in a glasshouse at Provo, UT, USA from 2020-2021. Grass was grown in pots arranged in a randomized complete block, full factorial design, with four replications of each treatment. The moderate KBG was also significantly different from both high and deficit for verdure and for the last half of NDVI. The objective of the field study was to evaluate two HBG cultivars (‘Tahoma 31’ and ‘Latitude 36’) compared to a blend of KBG cultivars for water loss and canopy health, temperature, and growth when subjected to deficit, moderate, and high irrigation. The study was arranged in a randomized complete block, full factorial design with three replications per treatment, and was conducted at Provo, UT, USA throughout the summer of 2021. In both the glasshouse and field trials, the deficit irrigated KBG consistently scored lower for NDVI and visual turf quality than all other treatments, including moderate and high KBG. This same trend was seen in the field study for percent cover. Although not observed in the glasshouse trial, it was observed in the field trial that the different irrigation levels of HBG resulted in no significant differences for any measurements but the HBG regularly scored better than KBG. The canopy temperatures of deficit irrigated KBG were also higher than all other treatments on most dates. The shoot mass, thatch mass, and total biomass of KBG were significantly less than either HBG cultivar. In the glasshouse trial it was observed that all deficit grasses were significantly lower than the other irrigation treatments and HBG had significantly deeper roots than KBG, although these results were not seen in the field trial. The data suggest that irrigation needs will be less for HBG than KBG and that HBG could provide a water-saving turfgrass alternative to KBG in semi-arid, cool-season regions with increasing water scarcity.

Subject of this master´s thesis is a station testing of Mobile automated astronomical system No. 1 (MAAS – 1). This system is used for measurement of astronomical coordinates by measurments of the stars. This thesis is focused on impact of some systematic effects, especially effects of inaccurate input geographic coordinates to resulting coordinates.

Relationship between the UV index and selected parameters Abstract Ultraviolet radiation (UV radiation) is a shortwave radiation with wavelengths from 100 to 400 nm. This radiation has both positive and negative effects on living organisms and human health. Therefor the so-called UV index (UVI), characterizing the biological effect of UV radiation on human health was defined in 1994. This thesis aims to evaluate the link between selected factors (total ozone column, solar elevation angel, cloudiness and altitude) and the UVI values. Observed data at four stations in Czechia (Hradec Králové, Košetice, Kuchařovice, Labská bouda) and SYNOP reports from the four nearest stations during the period 2010−2017 were used. The Sun elevation (angle of Sun ray) has the strongest effect on the UVI values. The highest UVI values are generally reached at high angels when the Sun rays go the shortest path through the atmosphere. The increase of the UVI is exponential, from an angle of 30ř the increase is approximately linear. The UVI values increase on average by 0.8 at the Hradec Králové station and by 0.9 at the Labská bouda station for angle increasing by 5ř. The effect of clouds is significant and depends on the height and the clouds amount. High level clouds reduce UVI negligible, overcast sky by only 15 %. Medium and...

L’objectif de ce mémoire était d’évaluer l’influence de la latitude, de variables abiotiques et du type de tourbières (bog ou fen) sur la diversité des plantes vasculaires et des bryophytes. Des inventaires ont été réalisés dans 380 tourbières du nord-ouest du Québec (49° à 55° N). Les effets de la latitude, de la continentalité, du climat et de variables abiotiques locales sur la diversité α (richesse spécifique et dispersion fonctionnelle), la diversité β (indices LCBD) et la composition ont été évalués pour les deux groupes de plantes. La diversité α des bryophytes augmentait vers le nord, alors que la diversité α des plantes vasculaires présentait des patrons différents dans les bogs et les fens en réponse à la latitude. Il y avait une homogénéisation taxonomique et fonctionnelle vers le nord pour les deux groupes de plantes et dans les deux types de tourbières. Les variables environnementales avaient des effets différents sur les deux groupes de plantes, dépendamment de l’indicateur de biodiversité utilisé. La composition taxonomique et fonctionnelle des bryophytes et des plantes vasculaires étaient principalement structurées par les conditions locales contrastantes entre les bogs et les fens, tandis que les variations bioclimatiques le long du gradient latitudinal jouaient un rôle secondaire. Les futures études et politiques de gestion des milieux naturels devraient tenir compte de plus d’un indicateur de diversité et considérer les différences entre les deux écosystèmes et les deux groupes de taxons afin de planifier les efforts de conservation et afin d’évaluer les effets des changements environnementaux. / This study aimed to evaluate the influence of latitude, abiotic variables on vascular and bryophyte diversity in bogs and fens. Inventories were conducted in 380 peatlands in northeastern Québec (49° to 55° N). Changes in α-diversity (species richness and functional dispersion), β-diversity (LCBD indices) and composition in response to latitude, continentality, climate, and local abiotic variables were evaluated for both plant groups. Bryophyte α-diversity increased northward, while vascular α-diversity showed contrasting patterns in bogs and fens in response to latitude. Environmental variables had different effects on both species’ groups, and patterns varied depending on the diversity indicator used, as α- and β-diversity and functional and taxonomic diversity were often decoupled. There was taxonomic and functional homogenization with latitude for both groups of plants in both habitats. Bryophyte and vascular taxonomic and functional composition were primarily structured by contrasting local conditions in bogs and fens, while bioclimatic variations along the latitudinal gradient played a secondary role. These results highlight the contrasting biodiversity patterns in both peatland types and the importance of local habitat conditions in structuring vascular and bryophyte biodiversity. Therefore, future studies and policies should include more than one diversity indicator and consider the differences between ecosystems and taxon groups when evaluating the effects of environmental changes on biodiversity and planning conservation.

No description available.

Scintillation of Global Positioning Systems (GPS) signals have been extensively studied at low and high latitude regions of the Earth. It has been shown in past studies that amplitude scintillation is severe at low latitudes and phase scintillation is severe at high latitudes. Unlike low and high latitude regions, mid-latitude scintillation has not been extensively studied. Further, it has been suggested that mid-latitude scintillation is negligible. The purpose of this research is to challenge this belief. A multi-constellation and multi-frequency receiver, that tracks American, Russian, and European satellites, was used to monitor scintillation activity at the Virginia Tech Space Center. Analysis was performed on collected data from various days and compared to past research done at high, mid, and low latitudes. The results are discussed in this thesis. / Master of Science / Earth’s atmosphere disrupts signals transmitted by Global Navigation Satellite Systems (GNSS). In certain regions of the Earth, these signals can be severely degraded. Not much research has been done on what could potentially happen to GNSS signals at mid-latitude regions of the Earth. It is important to gain a better understanding of the impacts mid-latitude regions can have on GNSS signals, in preparation for potential future outages across the system. The United States and Russia have had Global Positioning Systems (GPS) technology for decades. Today, China and Europe are expanding their global positioning systems. In the future there may be up to one hundred or more satellites available for public usage. This study was done to determine if outages could potentially occur at mid-latitudes, and to gain more knowledge on which of these satellite constellations have the best service.