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The purpose of the project described in this paper has been to complete construction and to determine the operating characteristics of a charging system and a corona-type controlled leakage system for the compact Van de Graaf generator now under construction at North Texas State University. Calibration data of the generating voltmeter to be used for determining the potential developed by the generator are also included in the paper.

Title: From fish flu to corona crisis – a quantitative content analysis of front pages from Dagens Nyheter and Aftonbladet during the coronavirus outbreak. The aim of this essay was to examine the reporting and framing of the coronavirus on DN.se and Aftonbladet.se's front pages, between January 7, 2020 and April 30, 2020. In order to do so, we chose to examine front page teasers on both newspapers front pages online. We define front page teasers as the package of text and pictures on the front page, which then takes the reader to the actual article. We formulated three questions to concretize the aim: ​How much space is given to the front page teasers about the coronavirus on Dagens Nyheter and Aftonbladet's front pages, in terms of number, size and location? ​How do the front page teasers frame the coronavirus on Dagens Nyheter and Aftonbladet's front pages, regarding to framing and perspectives as well as calming or alarming signals? And, ​what differences and similarities can be found between Dagens Nyheter and Aftonbladet’s front page teasers about the coronavirus, regarding to space and shape? ​The method chosen for this study was a quantitative content analysis, which was supported by theories about news values, media logic and narration, as well as the agenda setting theory and the framing theory. The results of the analysis stated that front page teasers about the coronavirus was given more space on both newspapers’ front pages during the majority of the selected time period, than front page teasers about other events. This could be explained by multiple theories about how threats, risks and crises, as well as sensational news, stand a better chance of making it to the front page, than other news. The analysis also showed that Dagens Nyheter chose to frame the coronavirus based on themes such as healthcare and economical consequences, while Aftonbladet chose a more human perspective. We speculated on how these results could affect the readers and their picture of reality – in this case the coronavirus – and came to the conclusion that Aftonbladet’s readers might feel more of a closeness to the coronavirus, than the readers of Dagens Nyheter. So, regarding to space – both in number and size – as well as theme, actor and signal, but also the newspapers’ own choice of words, our study made it possible for us to see how the “fish flu” gradually turned into a corona crisis.

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The work presented in this thesis describes an investigation into the properties and behaviour of nonlinear optical guest molecules doped into polymeric matrices. The interactions of the guest molecule 2-(N, N dimethylamino)-5-nitroacetanilide (DAN) with a polycarbonate and polymethyl methacrylate (PMMA) host are compared. A detailed characterisation of the two systems is described employing infra red spectroscopy and analysis of the chromophore alignment during electric field poling. The study reveals that hydrogen bond formation between the guest and the polar polycarbonate backbone accounts for the unusually good alignment stability previously reported in the polycarbonate system. The molecular hyperpolarisibility of DAN in PMMA is also measured and the apparent enhancement compared with solution measurements is accounted for by the more polar nature of the polymer environment. A new technique allowing the measurement of the dipole moment of polar molecules doped into thin polymer films is also presented. The technique is demonstrated on a series of zwitterionic chromophores whose measured dipole moments range from 30 to 40 D. Electrochroism measurements are performed to account for aggregation of the monomer species which then permits the first hyperpolarisibility of the molecules to be calculated. The values of dipole moment and hyperpolarisibility are found to be very sensitive to the choice of dielectric cavity shape used when deriving the local field correction factors. The measured values are therefore compared with theoretical calculations and a preferred cavity shape is proposed.

The high altitude balloon operations at Esrange Space Center have been goingon since 1972, and about 550 launches have been performed. Their present service system for the high altitude balloons is about 18 years old. To be able to meet the requests from their customers, SSC have started the development of a new service system. A service system contains all features and technology required to perform a high altitude balloon mission. This system is separated from the payload. Important design aspects for the new service system have been investigated to be able to leave recommendations to SSC. These are frequency for the radio communication, modulation scheme for the communication link, prevention of corona discharge, and available computer systems to be used as on-board computers. These design aspects have been evaluated according to the requirements for the development project. Theory, articles, available standards and analyzes have been read and evaluated to reach a conclusion about these subjects. It was found that the best frequency bands are the 400MHz-band, downlink, and the 450MHz-band, uplink. The operation in these bands will be unmodified for many years, and the link suffers little loss. The 2.3GHz-band is interesting from an international perspective, and it is suggested that SSC work to get a band dedicated to aeronautical services in this band. The best modulation scheme for the service system is GMSK, as it has very good spectral eficiency. The corona discharge can only be prevented indirect by SSC, as the phenomena occurs within or between components, aspects which SSC can't control. Standardized methods for tests and specications lists was suggested to minimize the risk of a discharge. The best computer system is an in-house designed service system that have been used on sounding rockets. It fits the present requirements the best. It suggested that the Beaglebone Black should be implemented in basic systems, providing processing and storage via simple serial communication, as it is a very cost eficient solution.

In this thesis the production and filtration performance of electrospun nylon-4,6 nanofiber mats was experimentally studied. The average fiber diameter of nylon-4,6 fibers is controlled by altering the polymer concentration in solution. Adding small amount of pyridine to the electrospinning solution controlled fiber beading and other defects. These fibers were then deposited onto a wide variety of conductive and dielectric substrate materials. A corona ion source was used to eliminate surface charging effects observed at the surface of all substrates. The resulting fiber mats, uniform in size and distribution as verified by SEM imaging, are tested for filtration efficiency and pressure drop. A Figure of Merit (FOM) is calculated for each filter produced and compared to high-grade commercial filters.

Trabajo de Investigación Requisito para optar al Título de Cirujano Dentista / Autor no autoriza el acceso a texto completo de su tesis en el Portal de Tesis Electrónicas / Introducción: El traumatismo dentoalveolar (TDA) corresponde a una lesión traumática que afecta a los tejidos duros del diente, la pulpa, y a las estructuras de soporte que lo rodean como son el periodonto y el hueso alveolar, consecutivo a un impacto violento. Este tipo de traumatismo puede afectar a la dentición temporal, mixta o permanente (1, 2, 3). Constituye uno de los motivos más frecuentes de consulta en los Servicios de Urgencias pediátricos (5, 6). El TDA en la dentición permanente daña principalmente las estructuras duras del diente, provocando la mayoría de las veces pérdida de tejido coronario y alteración de la formación radicular, dando origen a una formación radicular incompleta o enanismo radicular (7). La fractura coronaria no complicada de esmalte dentina, es la lesión más frecuente en dentición permanente, generalmente afecta a un solo diente, pero puede estar asociada a lesiones de los tejidos de soporte como, concusiones, subluxaciones, luxaciones intrusivas, extrusivas y laterales. El propósito de este estudio es conocer y comparar el pronóstico de dientes con fractura coronaria de esmalte dentina con lesión concomitante de los tejidos de soporte, con fracturas coronarias de esmalte dentina sin lesiones asociadas, evaluando la supervivencia pulpar, la obliteración del canal pulpar (OCP), la progresión del desarrollo radicular, necesidad de tratamiento endodóntico, considerando además la influencia de la edad, el sexo y el uso de férula durante el tratamiento. Material y Método: Se realizó un estudio retrospectivo de corte transversal, para lo cual se acudió al Servicio Dental de la Unidad de Emergencia del Hospital de Niños Dr. Roberto del Río, ubicado en la comuna de Independencia. Se recopilaron las fichas clínicas de los pacientes entre 6 y 14 años con fractura coronaria no complicada de esmalte y dentina más lesión de los tejidos de soporte que fueron atendidos en el servicio, con el objetivo de demostrar que las fracturas coronarias no complicadas de esmalte y dentina tienen mal pronóstico cuando están asociadas a lesiones concomitantes de los tejidos de soporte. Resultados: De un total de 1400 niños, de edades entre 6 y 14 años que acudieron al servicio dental, se seleccionaron las fichas pertenecientes a 221 pacientes, con 279 dientes afectados, de los cuales el 65% tenían fractura coronaria no complicada de esmalte dentina, el 25% fractura coronaria con lesión concomitante sin desplazamiento de los tejidos de soporte y el 10% fractura coronaria con lesión concomitante con desplazamiento. En todos los tipos de lesión, el sexo más afectado fue el masculino (64,3% a 71,4%). El rango de edad más frecuente fue entre 6 y 9 años. La mayor parte de los niños atendidos provenían del área Norte (51%). El lugar donde mayoritariamente ocurrieron los traumatismos fue en el colegio. Alrededor del 50% de los casos estudiados tenían formación radicular incompleta, los casos con lesión concomitante con desplazamiento fueron los que mayoritariamente emplearon férula (92,9%), el 60,7% de estos casos necesitaron tratamiento endodóntico, desarrollaron OCP post tratamiento el 10,7%, continuaron su desarrollo radicular el 100%, y el 64,3% de los casos tuvieron un gran seguimiento. Conclusión: Se observó que existe una leve asociación entre ser hombre y tener mayor necesidad de tratamiento endodóntico, pero no es estadísticamente significativo. A su vez, ni los grupos de edad, ni los dientes con formación radicular completa respecto de la incompleta se asocian con un mayor riesgo de necesitar tratamiento endodóntico, sin embargo, las piezas dentarias con fractura coronaria no complicada de esmalte dentina, con lesión concomitante con desplazamiento si mostraron la necesidad de tratamiento endodóntico pronóstico.

Owing to their inherent isolation and ability for remote interrogation, wireless sensors are an effective way to monitor the operation of high-voltage power transmission lines. A wireless sensor on a high-voltage line has the potential to form corona discharges, particularly on an exposed antenna. The effects of corona formation on the antenna of a wireless radio frequency (RF) communication system were studied. The physics of corona plasma formation and charge composition was analyzed, leading to a theoretical understanding of corona interaction with the antenna. Through a series of high-voltage experiments, the effects of corona on the impedance and gain of an antenna, as well as the RF interference generated by corona current pulses, were identified. RF interference and low-frequency corona current were observed to have the largest impact on a wireless RF system. Corona was found to have no significant impact on the impedance or gain of an antenna. Based on the results, design guidelines were proposed for an antenna and RF front end to be used in wireless high-voltage sensing applications.

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