RF-signaalin siirtomenetelmiä vastaanottokeloille magneettikuvauslaitteen ja lineaarikiihdyttimen integraatiossa

MR-Linac is an integration of a magnetic resonance imaging system and a linear accelerator. It is used to deliver image-guided radiation therapy treatments for patients with cancer. It can deliver higher doses with better accuracy than traditional radiation therapy treatment tools. The goal of this thesis work was to develop a way to transmit a 63.87 MHz RF-signal through a radiation window in an MR-Linac receive coil. Transmitting the received signal through the radiation window would enable the development of MR-Linac receive coils with higher signal-to-noise ratio and reduced imaging time. When transmitting signals in the radiation window the transmission lines must be designed to have a minimal linear accelerator radiation attenuation and a sufficient radiation resistance. Three different transmission line methods where tested and compared: micro-coaxial cable, microstrip line and coplanar waveguide. The most promising results were achieved with the microstrip line. The coplanar waveguide was not usable for the application because of its strong coupling to the surrounding environment.MR-Linac on magneettikuvauslaitteen ja lineaarikiihdyttimen yhdistelmä. Siinä käytetään magneettikuvia apuna syöpäpotilaiden säteilyhoidossa. Magneettikuvien ansiosta potilaille voidaan antaa paremmalla tarkkuudella suurempia säteilyannoksia kuin perinteisissä säteilyhoitomenetelmissä. Tämän diplomityön aiheena oli 63,87 MHz:n signaalin siirtäminen MR-Linacin vastaanottokelan säteilyikkunan läpi. Vastaanotetun signaalin siirtäminen säteilyikkunan läpi mahdollistaisi vastaanottokelojen suunnittelun, joilla saavutettaisiin suurempi signaali-kohinasuhde ja lyhyempi kuvausaika. Siirrettäessä signaalia säteilyikkunassa siirtolinjojen tulee vaimentaa lineaarikiihdyttimen säteilyä mahdollisimman vähän ja kestää korkeaenergisen säteilyn pitkäaikaiset vaikutukset. Kolmea erityyppistä siirtolinjaa testattiin ja vertailtiin: mikro-koaksiaalikaapelia, mikroliuskajohtoa ja koplanaarista johtoa. Mikroliuskajohdolla saatiin kaikista lupaavimpia tuloksia. Koplanaarinen johto osoittautui tässä käyttötarkoituksessa täysin käyttökelvottomaksi sen voimakkaan kytkennän takia

The Spores of Life and Death

Fungi are key players in ecosystems. They sustain life, affect the transformation of life forms, and are crucial actors in recycling carbon and minerals back into the common cycle. In addition to the author, three mushrooms are involved in the constellation of this article. In Western art history, self-portraits are intertwined with the theme of death in multiple ways. This posthumanist art-based study asks how mushrooms challenge our understanding of death. The study is located in the framework of queer death studies. Queering death by providing a basis for fungi to grow is a comforting thought

AI-assisted anomaly detection from log data

As the production of software continues to increase, the volume of log data being generated is also on the rise. This surge in data has made it impractical for human operators to manually review each log line produced by software systems. This necessity has led to the development of automatic anomaly detection methods. Automatic anomaly detection methods would allow system operators to respond to incidents more quickly and improve the quality of the software. In the past, anomaly detection from log data relied heavily on predefined rules. However, with the complexity of modern software systems, finding experts for every system component to write these rules has become difficult. Additionally, it is very labor-intensive to implement these rules. This has spurred interest in unsupervised anomaly detection methods. The purpose of this thesis is to research which kind of methods can be used for automatic anomaly detection, what is required to use them in a production system, and how well deep learning-based methods would work with log data produced by hundreds of embedded devices. The thesis begins with a literature review to explore the various methods used for anomaly detection from log data. It then outlines the required infrastructure for efficient anomaly detection and concludes by testing the DeepLog Deep Learning method on real log data from a production system. The key findings suggest that the DeepLog model performs effectively for anomaly detection when trained in an unsupervised fashion. However, it is essential to ensure that anomalous samples do not dominate the training data. This can be achieved either by completely excluding them from the training set or by ensuring that no single anomalous sample overwhelms the entire dataset, which could lead to overfitting. Moreover, the training dataset can be continuously refined by eliminating recognized anomalous sequences and subsequently retraining the model

Discursive Legitimation Strategies in Presidential Statements: A Case Study of the United States and the Paris Agreement on Climate Change

This thesis studies how two US presidents, Barack Obama and Donald Trump, aim to (de)legitimate their respective decisions on either to join the Paris Agreement on Climate Change or to withdraw from it. The two presidents’ uses of discursive legitimation strategies are compared to see how they differ or resemble each other. In addition, the study examines how the used strategies relate to the larger socio-political context of the US and two different administrations and parties in terms of their respective climate policies. In order to examine what strategies the presidents used, a combination typology of legitimation strategies by Van Leeuwen (2007 and 2008) and Reyes (2011) was employed. The study also aimed to test how well the legitimation framework worked with this kind of topic, since it has not been previously applied similarly. A total of five presidential statements were analysed with the method of close reading. The analysis found that there were more differences than similarities between the presidents. Obama used mostly positive legitimation and the strategies of altruism, mythopoesis and moral evaluation, while Trump employed mostly negative delegitimation and the strategies of authorization, hypothetical future and rationalization. Noteworthy was that Obama employed all strategies, but Trump did not use altruism at all. This provides a niche for further research. It was concluded that the used strategies relate to the policies of the presidents’ political parties. Future research could study more profoundly the divide in US climate policies in terms of discursive legitimation. The study proved that the legitimation framework could be applied to a topic of this kind. However, the framework could be tested and developed further, since there are still some limitations

Minna Silver & Pirjo Uino (eds.): Tiedenainen peilissä. Arkeologian professori Ella Kivikosken elämä ja tutkimuskentät. Book review.

Non peer reviewe

Function follows form? : The role of analogies in discovering the Stone Age

Peer reviewe