This thesis details the application of a medium frequency (MF) Doppler radar to observations of meteoroids entering the Earth's atmosphere. MF radars make possible a greater height coverage of the meteor region (70 to 160 km) than conventional meteor radars. However this type of radar has generally been under-utilised for meteor observations, primarily due to the less than ideal radio environment associated with MF systems. This situation demanded selection of the most appropriate radar meteor techniques and in this respect a variety of techniques are evaluated for application at this frequency. The 2 MHz radar system used in this study is located at the Buckland Park research facility (35.6 deg. S, 138.5 deg. E), near Adelaide, South Australia and is operated by the Department of Physics of the University of Adelaide. This radar has the largest antenna of any MF radar with 89 crossed dipoles distributed over an area of about 1 km in diameter. Beam forming is achieved by varying the phase to groups of elements of the array. The array was constructed in the 1960's, and while having several upgrades, a preliminary examination of the array and associated systems indicated that a significant amount of maintenance work would be required to enable the system to be used for meteor observations. It was also apparent that the software used with the radar hardware for atmospheric studies was not suitable for processing meteor data. Thus a major refurbishment of the radar hardware, as well as the development of appropriate software, was initiated. The complete radar system was divided into its constituent components of antenna array, transmitter, receiver and computer systems. The transmitter and receiver systems were examined and various improvements made including increasing total output power and enhancing beam steering capability. Time domain reflectometry (TDR) techniques were extensively used on the antenna array, as many feed cables showed the presence of moisture. New hardware in the form of a portable power combining system was designed, constructed and tested to further increase radar experimental capabilities. Techniques were developed that verified system performance was to specification. Extensive night time observations of sporadic and shower meteor events were made over a two and a half year period. A particular study was made of the Orionids shower as well as other meteor activity on the night of 22 October 2000. Using the upgraded beam swinging features of the array, a narrow radar beam was used to track the shower radiant in an orthogonal sense so as to maximise the number of shower meteors detected. From each echo, various intrinsic meteoroid parameters were determined, including meteor reflection point angle-of-arrival using a five-element interferometer, echo duration and height; meteoroid speeds were determined using the Fresnel phase time technique. Meteor echoes belonging to the Orionids radiant were selected using a coordinate transform technique. The speed was then used as an additional discriminant to confirm the Orionid shower members. A second radiant, observed at a slightly higher declination is classified as also part of the Orionid stream. The sporadic meteor component in the data set was examined and found to exhibit speeds much higher than expected for sporadic meteors at the time of the observations. However, these results are consistent with a selection bias based on meteoroid speed, that is inherent in radar observations. The Orionid observations indicate that the refurbishment of the radar system and the introduction of new software for meteor analysis has been successfully achieved and that radar meteor studies can now be carried out routinely with the Buckland Park 2 MHz radar. Moreover it has been shown for the first time that meteoroid speeds can be determined with a MF radar operating on a PRF as low as 60 Hz. / Thesis (Ph.D.)--School of Chemistry and Physics, 2003.

This thesis details the application of a medium frequency (MF) Doppler radar to observations of meteoroids entering the Earth's atmosphere. MF radars make possible a greater height coverage of the meteor region (70 to 160 km) than conventional meteor radars. However this type of radar has generally been under-utilised for meteor observations, primarily due to the less than ideal radio environment associated with MF systems. This situation demanded selection of the most appropriate radar meteor techniques and in this respect a variety of techniques are evaluated for application at this frequency. The 2 MHz radar system used in this study is located at the Buckland Park research facility (35.6 deg. S, 138.5 deg. E), near Adelaide, South Australia and is operated by the Department of Physics of the University of Adelaide. This radar has the largest antenna of any MF radar with 89 crossed dipoles distributed over an area of about 1 km in diameter. Beam forming is achieved by varying the phase to groups of elements of the array. The array was constructed in the 1960's, and while having several upgrades, a preliminary examination of the array and associated systems indicated that a significant amount of maintenance work would be required to enable the system to be used for meteor observations. It was also apparent that the software used with the radar hardware for atmospheric studies was not suitable for processing meteor data. Thus a major refurbishment of the radar hardware, as well as the development of appropriate software, was initiated. The complete radar system was divided into its constituent components of antenna array, transmitter, receiver and computer systems. The transmitter and receiver systems were examined and various improvements made including increasing total output power and enhancing beam steering capability. Time domain reflectometry (TDR) techniques were extensively used on the antenna array, as many feed cables showed the presence of moisture. New hardware in the form of a portable power combining system was designed, constructed and tested to further increase radar experimental capabilities. Techniques were developed that verified system performance was to specification. Extensive night time observations of sporadic and shower meteor events were made over a two and a half year period. A particular study was made of the Orionids shower as well as other meteor activity on the night of 22 October 2000. Using the upgraded beam swinging features of the array, a narrow radar beam was used to track the shower radiant in an orthogonal sense so as to maximise the number of shower meteors detected. From each echo, various intrinsic meteoroid parameters were determined, including meteor reflection point angle-of-arrival using a five-element interferometer, echo duration and height; meteoroid speeds were determined using the Fresnel phase time technique. Meteor echoes belonging to the Orionids radiant were selected using a coordinate transform technique. The speed was then used as an additional discriminant to confirm the Orionid shower members. A second radiant, observed at a slightly higher declination is classified as also part of the Orionid stream. The sporadic meteor component in the data set was examined and found to exhibit speeds much higher than expected for sporadic meteors at the time of the observations. However, these results are consistent with a selection bias based on meteoroid speed, that is inherent in radar observations. The Orionid observations indicate that the refurbishment of the radar system and the introduction of new software for meteor analysis has been successfully achieved and that radar meteor studies can now be carried out routinely with the Buckland Park 2 MHz radar. Moreover it has been shown for the first time that meteoroid speeds can be determined with a MF radar operating on a PRF as low as 60 Hz. / Thesis (Ph.D.)--School of Chemistry and Physics, 2003.

Un vaste programme international est en cours pour déterminer les paramètres du phénomène d'oscillation des neutrinos et approfondir la connaissance de la matrice de mélange des neutrinos (MNSP). Le détecteur OPERA, qui est installé dans le laboratoire souterrain du Gran Sasso en Italie, a pour but principal de mettre en évidence l'apparition de neutrinos de type tau dans un faisceau de neutrinos initialement de type muon, produit au CERN (CNGS) 730 km en amont. Il est aussi en mesure de détecter les oscillations des neutrinos muon en neutrinos électron, donnant accès au paramètre de mélange sin(2θ13)2, où θ13 est le dernier angle de la matrice MNSP finalement déterminé en 2012 conjointement par Daya Bay, RENO et Double Chooz. Pour déterminer la présence des ντ dans le faisceau, le détecteur OPERA est composé de cibles calorimétriques utilisant une alternance de plaques de plomb et de films d'émulsion. Ceux-ci permettront de reconstruire les traces des particules chargées résultant des interactions neutrino avec une précision inégalable (de l'ordre du micron). La recherche des événements de signal d'oscillation νµ → νe sera basée sur l'aptitude à identifier les électrons, à rejeter les événements de fond où un π0 est produit et à soustraire le fond dominant intrinsèque provenant du faisceau. Ce travail de thèse a pour objectif l'élaboration de méthodes d'analyse pour améliorer les performances du détecteur OPERA dans la recherche d'oscillations νµ → νe . / An international program is ongoing to measure the neutrino oscillation phenomenon and to determine the neutrino mixing matrix (MNSP) parameters. OPERA is a long-baseline neutrino experiment located at the Gran Sasso Laboratory in Italy, 730~km from CERN, downstream in the CNGS neutrino beam. The OPERA experiment is designed and optimised for a direct appearance search of νµ → ντ oscillations. It can also detect the νµ → νe oscillation driven by sin(2θ13)2 , where θ13 is the last mixing angle finally measured by the Daya Bay, RENO, and Double Chooz experiments in 2012. To observe the presence of ντ interactions in the beam, the OPERA detector is composed of calorimetric targets made of a modular structure called the "brick": a sandwich of lead plates interspaced with emulsion layers. The latter allows reconstructing tracks of charged particles produced in the neutrino interactions with a micrometric resolution. The search for the νµ → νe oscillation signal is based on the capability of identifying the electrons, rejecting background events where neutral pions are produced and keeping under control the intrinsic and dominant background source from the beam contamination. This work aims to elaborate analysis methods to improve the OPERA detector performance in the νµ → νe oscillation search.

Après plus d'un siècle d'études, l'origine des rayons cosmiques d’ultra-haute énergie reste mal comprise. En améliorant la connaissance de la composition des rayons cosmiques détectés sur Terre, il est possible de contraindre les modèles concernant leur origine, ainsi que leur mécanisme de production dans les sources astrophysiques. Les simulations montrent que le champ électrique émis par les gerbes est sensible à leur développement dans l'atmosphère. Ce champ électrique peut être mesuré avec un cycle utile élevé, faisant du signal radio une observable prometteuse pour identifier le rayon cosmique primaire. Le signal radio permet également de mesurer sa direction d'arrivée et son énergie. Depuis 2006, l'observatoire Pierre Auger accueille plusieurs réseaux de radio détection des rayons cosmiques. Des démonstrateurs équipés de quelques stations (RAuger,MAXIMA) ont permis une caractérisation efficace de l'environnement radio du site, ils ont également apporté des contraintes sur les mécanismes responsables de l'émission du champ électrique par les gerbes dans le domaine du MHz. Les prototypes ont mené à la construction d’AERA (Auger Engineering Radio Array) qui, avec 124 stations couvrant 6 km², est le premier réseau grande échelle de radio détection des gerbes dans le domaine du MHz. AERA est déployé dans l'extension basse énergie de l'observatoire afin de bénéficier d'une statistique plus importante. Le réseau permet d'intéressantes mesures hybrides ; son emplacement permet en effet de croiser les données obtenues par la radio avec celles provenant du réseau de surface (SD) et des télescopes à fluorescence (FD) proches du réseau. Cette thèse est dédiée à la caractérisation de signaux transitoires radio détectés par RAuger et AERA. Comme un des défis de la radio détection des gerbes atmosphériques est de supprimer les bruits de fond anthropiques causant des déclenchements accidentels, des méthodes de réjection du bruit de fond et de sélection des coïncidences SD-AERA ont été développées. Une étude de la corrélation entre le développement de la gerbe dans l'atmosphère (profil longitudinal) et le champ électrique mesuré par les stations radio est également présentée. Cette étude valide le lien direct entre le champ électrique et le développement de la gerbe dans l'atmosphère et confirme l’intérêt du signal radio pour l’estimation de la nature des rayons cosmiques d'ultra-haute énergie. / After more than a century of studies, one of the challenging questions related to ultra-high energy cosmic rays concerns their nature, which remains unclear. Improving the knowledge about the composition of cosmic rays will permit to constrain the models concerning their origins and the production mechanisms in the astrophysical sources. Simulations show that, the electric field emitted by the shower is sensitive to its development. This electric-field can be measured with a high duty cycle, and thus is apromising technique to identify an observable sensitive to the nature of the primary cosmic ray. The radio signal is also used to measure its arrival direction and its energy. Since 2006, the Pierre Auger Observatory hosts several radio detection arrays of cosmic rays, starting from small size prototypes (RAuger, MAXIMA) to achieve a large scale array of 124 radio stations: AERA, the Auger Engineering Radio Array covering 6 km². These different arrays allow the study of the radio emission during the development of the shower in the MHz domain. AERA is deployed in the low energy extension of the Pierre Auger Observatory in order to have a larger statistics. It enables interesting hybrid measurements, with the comparison of radio observable with those obtained with the surface detector (SD) and the fluorescence telescopes close to the array. This thesis is dedicated to the characterization of the radio transient signals detected by RAuger and AERA. As one of the challenges of the radio detection of air-shower is to remove the anthropic background causing accidental triggering, methods for background rejection and SD-AERA coincidences selection have been developed. A study of the correlation between the shower development in the atmosphere (longitudinal profile) and the electric-field measured by the radio stations is also presented. This study shows the relationship between the electric-field and the shower development in the atmosphere and confirms that the radio signal is a powerful tool to study the nature of the ultra-high energy cosmic rays.

Les rayons cosmiques sont des particules chargées, ainsi que des coproduits comme les photons et les neutrinos, issus de sources de rayons cosmiques galactiques ou extragalactiques. Ils arrivent au sommet de l'atmosphère terrestre avec des énergies primaires allant jusqu'à quelques 10 EeV. Lorsque les rayons cosmiques entrent dans l'atmosphère, ils interagissent avec les molécules de l'air et produisent un grand nombre de particules secondaires, créant une gerbe atmosphérique (extensive air shower, EAS). Accompagné des particules secondaires, une émission de la lumière Cherenkov et de la lumière fluorescence est induite par le passage des particules dans l'atmosphère. L'Observatoire Pierre Auger et Large High Altitude Air Shower Observatory (LHAASO) sont des observatoires dédiés à la détection des gerbes atmosphériques dans le but de répondre aux questions ouvertes concernant les rayons cosmiques, mais se concentrant sur différentes gammes d'énergie, les plus hautes énergies et les énergies autour de quelques PeV. Après plus de 10 ans d'exploitation de l'Observatoire Pierre Auger, la collaboration Auger a proposé une amélioration des détecteurs de son réseau de surface, appelée "AugerPrime". Le but est d'augmenter la sensibilité à la masse des particules primaires en ajoutant un détecteur scintillateur sur le détecteur Cherenkov à eau. Les deux observatoires sont dits «hybrides» car composés de télescopes optiques observant le développement longitudinal des gerbes et des réseaux de détecteurs de surface échantillonnant leurs profils latéraux. Dans cette thèse, une série d'études contribuant aux projets AugerPrime et LHAASO sont présentées. En ce qui concerne le projet AugerPrime, la présente étude comprend le travail de recherche & développement des scintillateurs et l'analyse de données du réseau de tester. Pour le projet LHAASO, des simulations de télescopes Cherenkov et une analyse multivariée des observations hybrides pour l'identification des masses primaires sont présentées. / Cosmic rays are charged particles, as well as coproducts like photons and neutrinos, originated in cosmic-ray sources inside or outside the Galaxy. They arrive at the top of the Earth's atmosphere with primary energies of up to a few 10 EeV. When the cosmic rays enter the atmosphere, they interact with the molecules in the air and produce a large number of secondary particles, creating an extensive air shower (EAS). The ground-based observation of the EAS can be used to deduce the energy, the arrival direction, and the mass composition of cosmic rays. The Pierre Auger Observatory and the Large High Altitude Air Shower Observatory (LHAASO) are both EAS observatories aiming at solving open questions of cosmic-ray studies but focusing on different energy ranges, the highest-energy and the so-called knee (around few PeV) regions. Based on the experience gained during the operation of the Pierre Auger Observatory for more than 10 years, the Auger collaboration has proposed an upgrade project, called ''AugerPrime'', with the aim of increasing the sensitivity of the surface detector array to the primary mass of cosmic rays. Both observatories employ the so-called ''hybrid detector arrays'' composed of optical telescopes overlooking the longitudinal development and ground detector arrays sampling the signal densities in the lateral direction of the EAS. The ground detector arrays of both observatories are being constructed or upgraded to have various types of particle detectors (scintillator and water-Cherenkov detectors), which allow us to decompose the electromagnetic and muonic components of the EAS. In this thesis, a series of studies contributing to the AugerPrime and LHAASO projects are presented. Concerning the AugerPrime project, the present study includes R&D work of the scintillator detector and data analysis of the engineering array. For the LHAASO project, simulations of the wide field of view Cherenkov telescope array and a multivariate analysis of LHAASO-hybrid observations for the primary mass identification are presented.

Bakgrund: Postoperativ sårinfektion är den näst vanligaste vårdrelaterade infektionen i Sverige och många kan undvikas genom förebyggande arbetssätt. En viktig preventiv åtgärd är den preoperativa duschen. Sjuksköterskor upplever tidsbrist och stress vilket hindrar dem från att ge patienter tillräckligt med information och hjälp kring proceduren och patienter avviker från riktlinjer vid utförandet på grund av ofullständig information. Operationssjuksköterskan är ansvarig för hygien och aseptik i operationssalen och framhåller vikten av preoperativa hygieniska förberedelserna fördet slutgiltiga resultatet av huddesinfektionen.  Motiv: Genom att belysa vårdavdelningssjuksköterskors erfarenheter av preoperativa dusch kan kunskap skapas om eventuella utmaningar samt om hur dessa problem kan förebyggas vilket i sin tur kan öka möjligheter för att främja en patientsäker vård.  Syfte: Syftet var att beskriva avdelningssjuksköterskors erfarenhet av hygieniska preoperativa förberedelser av patient inför kirurgi. Metod: Semistrukturerade intervjuer i fokusgrupper genomfördes med sjuksköterskor som arbetar på kirurgvårdavdelningar. Insamlad data analyserades med kvalitativ innehållsanalys. Resultat: Resultatet presenterades i ett tema och de fyra kategorierna: “Kluvenhet kring betydelsen av preoperativ dusch”, “Behov av tydligare riktlinjer på avdelningen”, “Behov av tydligare arbetsledning” och “Acceptans kring att inte följa riktlinjer”. Konklusion: Sjuksköterskorna upplevde hinder som kunskapsbrist, personalbrist och tidsbrist vid de preoperativa hygienförberedelserna, vilket skapade känslor av osäkerhet, frustration och uppgivenhet. De beskrev en önskan om att ha rätt förutsättningar för att kunna följa nationella riktlinjer och ge omvårdnad av god kvalitet. / Background: Postoperative surgical site infection is the second most common cross infection in Sweden and many can be avoided by preventive measures. An important preventive measure is the preoperative shower. Nurses experiences lack of time and stress which prevents them from giving the patient sufficient information and assistance through the procedure and patients deviate from the guidelines due to lack of information. The operating room nurse is responsible for aseptic and hygiene in the operating room and emphasizes the importance of the preoperative shower for the final result of the skin disinfection.  Motive: By illustrate surgical ward nurses’ experiences of preoperative shower, knowledge can be created about possible challenges and how these problems can be prevented, which in turn can increase opportunities to promote a patient-safe care.  Aim: The aim of the study is to describe surgical ward nurses’ experiences of hygienic preoperative preparations of patient before surgery.  Methods: Semi-structured interviews in focus groups with nurses in a surgical ward were conducted. Collected data were analyzed with qualitative content analysis.  Result: The results were presented in one theme and four categories: “Hesitation of the importance of preoperative shower”, “Need of clearer guidelines in the surgical ward”, “Need of clearer leadership” and “Acceptance of not following guidelines”.  Conclusion: The nurses experienced obstacles such as lack of knowledge, lack of personnel and lack of time in the preoperative hygiene preparations, which created feelings of insecurity, frustration and abandonment. They described a desire to have the right conditions to be able to follow national guidelines and provide a good quality care.

Rock-a-Buy Baby: Consumerism by New, First-Time Mothers, is the first known sociological exploration of need-based consumption for babies, despite the baby gear industry being a $6-billion-dollar business (whattoexpect.com). Data stemmed from qualitative, semistructured interviews with new, first-time mothers (3 months – 1 year postpartum) conducted within participants‘ households. The insights gained from the present study tell us a great deal about the ―needs‖ that predominantly white, middle-class mothers socially constructed in anticipation of their first child, and the consumptive behaviors used to accomplish these "needs." Respondents had turned to similar resources (other mothers, online forums, consumer reports, books, magazines, etc.) to help them construct ―need‖ and formulate decisions among commodities. Provided they were relying on comparable, if not overlapping, bodies of knowledge, mothers‘ narratives about consumer ―need‖ were often congruent. Additionally, the ways expectant mothers accumulated items are ritualized and made tradition. The baby shower and gift registration process (which all of my respondents participated in to some variation) are social constructions; these practices, which are so strongly tied to consumption, also constituted reality for mothers, and inevitably, their babies.

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No description available.

O comportamento das interações hadrônicas para energias de centro de massa superiores a 50 TeV/núcleon é uma fonte importante de incerteza sistemática na interpretação de dados de observatórios de raios cósmicos. Nesta tese, estudamos por meio de simulações de Monte Carlo observáveis dos chuveiros atmosféricos que pudessem ser correlacionados com aspectos dos diferentes modelos destas interações. Especial atenção foi dada à componente muônica que sabidamente é gerada do decaimento de partículas de natureza hadrônica na cascata. A precisão e a acurácia de uma rede esparsa de contadores de múons foram estudadas como função da granularidade da rede de detectores e da área de coleção de suas células. Mostramos, em particular, as diferenças na dependência radial da densidade de múons no plano transversal ao eixo da cascata para os diferentes modelos. Tais diferenças se mostram mais acentuadas na vizinhança do eixo e poderiam ser exploradas experimentalmente com um detector com alcance dinâmico suficiente para evitar saturação da eletrônica. Além disso, por meio de um tratamento fenomenológico, investigamos o impacto no desenvolvimento do chuveiro causado por variações na distribuição de pseudorapidez $dN/d\\eta$ de secundários produzidos na colisão primária. Mostramos que diferentemente de quantidades como seção de choque inelástica, multiplicidade, razão de carga e elasticidade, mudanças em $dN/d\\eta$ que preservem tais quantidades são rapidamente diluídas nas sucessivas camadas de interações posteriores à colisão primária. / The behavior of the hadronic interactions at center of mass energies greater than 50 TeV/nucleon is an important source of systematic uncertainty on interpreting data from cosmic ray observatories. In this thesis, we study through Monte Carlo simulations the atmospheric shower observables that could be correlated with different aspects of these interactions. Special attention was paid to the muonic component that is known to be generated from the decay of hadronic particles. The precision and accuracy of a sparse grid of muon counters were studied as a function of the array granularity and the collection area of its cells. In particular, we studied the differences in the radial dependence of the muon density in the shower plane for different models. These differences are shown to be larger in the vicinity of the shower axis and, therefore, could be explored with a detector of sufficiently large dynamic range as to avoid saturation of its acquisition electronics. In addition, through a phenomenological treatment, we investigated the impact on the shower development caused by variations in the distribution of pseudorapidity $ dN/d\\eta $ of secondaries particles produced in the primary collision. We show that unlike quantities such as inelastic cross section, multiplicity, charge ratio and elasticity, changes in $ dN/d\\eta $ that preserve such quantities are rapidly diluted in successive interaction layers subsequent to the primary collision.