5,497 research outputs found

    The multi-phase ISM of radio galaxies: a spectroscopic study of ionized and warm gas

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    Actieve galactische kernen horen tot de meest energetische bronnen van het universum. Deze bevinden zich meestal in het centrum van massieve sterrenstelsels waarbij hun energie ontstaat door middel van accretie van materiaal op een super zwaar zwart gat. Het licht dat uitgezonden wordt door een actieve galactische kern kan het licht afkomstig van de sterren in zijn sterrenstelsel sterk domineren. Sommige actieve galactische kernen zijn in staat om krachtige tweezijdige stralen van relativistische deeltjes te lanceren, deze noemt men radio sterrenstelsels. Actieve galactische kernen kregen toenemende aandacht in het vakgebied van de evolutie van sterrenstelsels, omdat men aangetoond heeft dat ze in staat zijn om gas te verwarmen of te verwijderen uit hun sterrenstelsel. De interactie tussen de energie die uitgezonden wordt door een actieve galactische kern met het materiaal in zijn sterrenstelsel wordt ook wel 'AGN-feedback' genoemd. Dit wordt als een van de belangrijkste mechanismen gezien die verantwoordelijk is voor het verlagen van stervorming in massieve melkwegstelsels. In mijn proefschrift bespreek ik een aantal open vragen met betrekking tot AGN-feedback en de mechanismen die betrokken zijn bij de accretie van gas op een super zwaar zwart gat. Dit is gedaan door middel van het bestuderen van gas in radio sterrenstelsels met behulp van verschillende observatietechnieken, voornamelijk in het optische en infrarode domein. Om het effect te begrijpen die de tweezijdige stralen kunnen hebben op het gas in het sterrenstelsel, heb ik een aantal radiosterrenstelsels bestudeerd. Deze sterrenstelsels stelden mij in staat om de complexiteit en de vele facetten van het AGN-feedback fenomeen te onderzoeken en waarderen

    Exposure of farm workers to electromagnetic radiation from cellular network radio base stations situated on rural agricultural land

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    The electromagnetic field (EMF) levels generated by mobile telephone radio base stations (RBS) situated on rural-agricultural lands were assessed in order to evaluate the exposure of farm workers in the surrounding area. The expected EMF at various distances from a mobile telephone RBS was calculated using an ad hoc numerical forecast model. Subsequently, the electric fields around some RBS on agricultural lands were measured, in order to obtain a good approximation of the effective conditions at the investigated sites. The viability of this study was tested according to the Italian Regulations concerning general and occupational public exposure to time-varying EMFs. The calculated E-field values were obtained with the RBS working constantly at full power, but during the in situ measurements the actual power emitted by RBS antennas was lower than the maximum level, and the E-field values actually registered were much lower than the calculated values

    Robotic double-loop reconstruction method following total gastrectomy

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    Minimally invasive surgery for gastric cancer is a challenge. The reconstructive time is a particular issue and researchers have adopted a large variety of solutions and produced heterogeneous data. The reconstructive phase can be divided into two major categories based on the approach adopted: the execution of extracorporeal versus intracorporeal anastomosis. In turn, the surgical team can perform the latter with laparoscopic or robotic assistance. However, the question is, how should a robotic esophagojejunal anastomosis be performed after total gastrectomy? Most articles in the literature have reported the execution of mechanical anastomoses [1] [2] [3] [4] [5] [6], especially with circular staplers via the creation of a manual purse-string around the anvil. Other solutions have described the use of the Orvil or the overlap technique. Only three authors have reported intracorporeal sutures with a completely robotic-sewn anastomosis [7] [8] [9]. A new robotic technique (the Parisi technique) was developed and adopted at St. Mary’s Hospital, Terni, Italy. A double-loop reconstruction method with an intracorporeal robot-sewn anastomosis is performe

    La riqualificazione della viabilità costiera per la mobilità dolce: il caso di Palermo

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    The attractiveness and the availability of services offered in urban areas nearby the port terminals are conditioned by the improvement of the connection of different urban transport systems and by the enhancement of the accessibility. But they should be based on the overall improvement of urban mobility. The structural organization of the territory is favored by the presence of links, which realize an infrastructure system to the different levels of connection and accessibility. The interventions could include the requalification of the coastal strip, including the road network component. Attention should be given to the supply quality, the rationalization of a linear model based on the coastal viability and on the access to the poles of the city and its hinterland. It should be also took in to account a rationalization of urban traffic, using exchange parking areas with enhanced public transport systems, and of the creation of pedestrian and bicycle paths for soft mobility on the short and medium range distances

    Recycling of Pre-Washed Municipal Solid Waste Incinerator Fly Ash in the Manufacturing of Low Temperature Setting Geopolymer Materials

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    In this work, three samples of municipal solid waste incinerators fly ash (MSWI-FA) have been stabilized in systems containing coal fly ash to create geopolymers through a polycondensation reaction. Monolithic products have been obtained with both MSWI fly ash as received and after the partial removal of chloride and sulfate by water washing. The polycondensation products have been characterized qualitatively by means of Fourier transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy and quantitatively, through the determination of the volume of reacted water and silicate. Furthermore, the heavy metals and chloride releases together with the physico-mechanical properties have been evaluated on the hardened products. In conclusion, considering the technological and environmental performances of the obtained geopolymers, they could be suitable for many non-structural applications, such as backfilling of abandoned quarries, decorative materials or brick fireplaces, hearths, patios, etc
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