Under vissa typer av operationer, till exempel då kärlen kring hjärtat opereras, använder sig läkare av en speciell typ av röntgenmaskin för att orientera sig inuti kroppen, så kallad genomlysning. För att undgå att öppna upp bröstkorgen på patienten går läkarna in med små verktyg i kärlen via ljumskarna och upp till hjärtat. Eftersom läkarna står så nära patienten träffar en del av strålningen de"Background: Cataract (opacity of the lens of the eye) has always been thought of as a deterministic effect. That is, that there is a threshold dose below which damage does not occur. However, recent studies suggest a lower threshold and the question whether there is any threshold at all has been raised. One situation that leads to special concern, if this turns out to be the case, is during

En mycket vanlig behandlingsteknik vid cancer är strålbehandling. Tekniken har utvecklats snabbt de senaste åren och idag uppnås millimeterprecision för många behandlingsområden. Därmed har behovet av att kunna kompensera för rörelser under behandlingen ökat. I detta arbete undersöktes möjligheten att låta strålgången följa tumören med en teknik som kallas MLC-tracking. Strålbehandling började a"Purpose: To investigate the geometric accuracy of MLC-tracking using a circular field, and to investigate the dosimetric accuracy for inversely optimized arc delivery to a moving target. This is done for two different MLCs and for varying plan complexity. Materials and methods: For investigating the geometric accuracy, a marker was placed on a motion platform while the MLC set to shape a ci

Intensity-modulated radiation therapy (IMRT) has during the recent years become a frequently used technique in radiotherapy. Lately IMRT has also been combined with rotational beam delivery, with a simultaneously moving couch, a technique called tomotherapy. The great benefit with this treatment method is the ability to give highly conformal treatments, with high dose to the tumour, while sparing

The aim of this master thesis was to develop a rotation-based collimation system for large coaxial high-purity germanium detectors for use in intense radiation fields. A collimator was constructedformed as a cylinder surrounding the detector, with a 90° slit opening to the detector. The rotational asymmetry caused by the slit was used to trace the direction of the incident gamma rays as well as re

A new method to extract mass density and elemental compositions of tissues from dual-energy computed tomography (DECT) scans is described and investigated. The method decomposes a tissue into proportions of two or three predened base materials and was proposed in 2008 by a research team at Linkoping University. Informations of tissue parameters may be important in radiation treatment planning to c

When doing mobile gamma-spectrometry the equipment has for severaldecades been limited to NaI(Tl) and Ge-based detectors. Recent developements has led to a possible replacement of NaI(Tl)-based systems in the form of a new scintillation material: LaBr3:Ce (cerium doped lanthanum bromide). LaBr3:Ce-detectors successfully compete with NaI(Tl)-based detectors when considering resolution, efficiency,

Syftet med denna studie är att utreda möjligheterna för Öresundskraft AB att utvinna marin förnyelsebar energi från norra Öresund. Studien genomförs i två delar där Öresunds fysikaliska egenskaper samt marina krafttekniker kartläggs i den första för att sedan analysera den möjliga miljöpåverkan från de alternativen som kan vara intressanta i Öresund. De marina energitekniker som studerades var OTEThe purpose of this study is to determine the possibilities for Öresundskraft AB to derive marine renewable energy from northern Öresund, the sound between Sweden and Denmark. The physical properties of the sound, such as temperature, current speed, wave height, salinity gradients, bathymetry, are researched as well as which technologies are present in the current marine renewable energy market. T

Populärvetenskaplig sammanfattning Modern kommunikationsteknologi genererar dataset som kan hjälpa samhällsvetenskapen att förstå hur vi kommunicerar: när vi skickar meddelanden, till vilka och hur vi organiserar våra sociala nätverk på nätet. Storleken på kommunikationsdataset gör att man måste an-vända enkla mekanistiska modeller av samma typ som förekommer i statistisk fysik för att förstå desWe investigate an online community where people meet and communicate in forms of discussions or sending messages to each other. We try to see the big picture of communications and social activities by network analysis. Specifically, in this social network, there are two modes of communications. Either a user can reply to others in a public forum in such a way that we see who comments on whom; or t

Detta arbete handlar om att utveckla och förbättra en försöksuppställning som kan mäta laserinducerad fosforescens både spektralt och tidsupplöst. Ämnet som emitterar fosforescensen befinner sig i en kalibreringsugn som kan värmas till olika temperaturer vilket möjliggör studier av irreversibla åldringsprocesser i ämnet som funktion av temperatur och tid. Fosforescens är den långa efterglöd som fo

Detta arbete har syftat till att göra en situationsstudie av dissipation beräknad i HIRLAM, en numerisk prognosmodell, över Danmark och att ge författarna kunskap om fenomenet turbulens. Studien gjordes genom att bearbeta data erhållen från HIRLAM i MATLAB. Den nedersta delen av troposfären där jordytan har en påverkan på atmosfären kallas för gränsskiktet. När vinden blåser i gränsskiktet kommer This case study aimed at analyzing dissipation calculated in HIRLAM, a numerical forecast model, over Denmark and to give the authors more knowledge about the phenomenon of turbulence. The study was done by processing data obtained from HIRLAM in MATLAB. The lowest part of the troposphere where the surface of the earth has an impact on the air is called the planetary boundary layer. When the wind

Åska hör till ett av de farligaste fenomenen som finns i vår atmosfär. Intresset av att observera åska har alltid funnits hos människan. Först på senare tid har man börjat förstå fysiken bakom fenomenet, även om det fortfarande finns många luckor i kunskapen. Sedan 2000 använder Danmarks Meteorologiska Institut blixtlokaliseringssystemet IMAPCT, som bland annat registrerar nedslagspunkt, strömstyrThunderstorms are one of the most dangerous phenomena in our atmosphere. Mankind has always been interested in observing thunderstorms. It is only recently that we have begun to understand the physics behind this phenomenon. However, there are still many gaps in the knowledge. Since 2000, Denmark has been using the lightning locating system IMPACT which registers strike point, average amperage and

This report constitutes that there are factors that may affect capacity assessment within municipal risk- and vulnerability analysis. The scope is an interview survey investigating the attitudes of operators within the municipal emergency preparedness towards factors that could potentially affect the outcome of capacity assessment. Six Influencing factors are identified comprising; 1 Selection re

This master thesis investigates how municipalities can use action program for its safety work and how the municipality of Umeå can improve its work with such a program. Information has been gathered through literature studies and case studies involving the municipality of Umeå, four other municipalities and some of the responsible authorities for the area. Conclusions reached out is that an action

This study looks at nationalism in China since the 1980s. It attempts to examine whether nationalism is increasing by investigating whether an increase is reflected in the arts, in particular Chinese cinema. The logic behind this is that if nationalism is a politicisation of arts, tradition and culture then an increase in nationalism should be reflected in arts, tradition and culture. The topic of

This report evaluates an existing method for testing water mist systems - CEN/TS 14972:2008. Annex A.3. The evaluation is to be seen as an analysis of the uncertainties with respect to repeatability and reproducibility of the test. It is concluded that the test method does not meet the standards required to become an EN-standard in its present form. A new concept is presented and verified, bot the

The capacity of an emergency response system is a deciding factor in its design and development, as well as its consequent success. Given this perspective, it is obvious that it is meaningless to do a risk analysis of a system without examining or knowing its capacity first. But how is capacity evaluated? A literature study was done to find existing methods and it revealed that capacity is a conce

This bachelor’s thesis is an anthropological analysis of the ghetto debate in Denmark taking place from October 2010 to April 2011. Considering the different actors in the debate; the politicians, the ethnic minorities as well as the ethnic Danish residents of the ghetto, and the Danish population in general it will become clear that the debate about ghettos is very different between those trying

In online auctions bidding frequency tends to increase towards the last minutes of the auction. This thesis investigates why bidders might choose to engage in last minute bidding, sniping, in Tradera auctions (Tradera is a Swedish subsidiary of eBay). Tradera uses a hard-close rule and a second-price rule. In hard-close auctions the dead-line occurs at a specific time, after which new bids are not

The purpose of this thesis was to study about the implication of Mandarin language in creating unity among ethnic Chinese in Malaysia. The research was carried out by exploring the role of Chinese school in order to produce an analytical overview of language and unity in Malaysian Chinese context. The identity issue was also being analyzed to find out how Mandarin language helps to create Chinese