Trigger and data link system for CMS Resistive Plate Chambers at the LHC accelerator

The purpose of the work was to realize a high-speed digital data transfer system for RPC muon chambers in the CMS experiment on CERN’s new LHC accelerator. This large scale system took many years and many stages of prototyping to develop, and required the participation of tens of people. The system interfaces to Frontend Boards (FEB) at the 200,000-channel detector and to the trigger and readout electronics in the control room of the experiment. The distance between these two is about 80 metres and the speed required for the optic links was pushing the limits of available technology when the project was started. Here, as in many other aspects of the design, it was assumed that the features of readily available commercial components would develop in the course of the design work, just as they did. By choosing a high speed it was possible to multiplex the data from some the chambers into the same fibres to reduce the number of links needed. Further reduction was achieved by employing zero suppression and data compression, and a total of only 660 optical links were needed. Another requirement, which conflicted somewhat with choosing the components a late as possible was that the design needed to be radiation tolerant to an ionizing dose of 100 Gy and to a have a moderate tolerance to Single Event Effects (SEEs). This required some radiation test campaigns, and eventually led to ASICs being chosen for some of the critical parts. The system was made to be as reconfigurable as possible. The reconfiguration needs to be done from a distance as the electronics is not accessible except for some short and rare service breaks once the accelerator starts running. Therefore reconfigurable logic is extensively used, and the firmware development for the FPGAs constituted a sizable part of the work. Some special techniques needed to be used there too, to achieve the required radiation tolerance. The system has been demonstrated to work in several laboratory and beam tests, and now we are waiting to see it in action when the LHC will start running in the autumn 2008.

Photodamage to Oxygen Evolving Complex - An Initial Event in Photoinhibition of Photosystem II.

Photosystem II (PSII) of oxygenic photosynthesis is susceptible to photoinhibition. Photoinhibition is defined as light induced damage resulting in turnover of the D1 protein subunit of the reaction center of PSII. Both visible and ultraviolet (UV) light cause photoinhibition. Photoinhibition induced by UV light damages the oxygen evolving complex (OEC) via absorption of UV photons by the Mn ion(s) of OEC. Under visible light, most of the earlier hypotheses assume that photoinhibition occurs when the rate of photon absorption by PSII antenna exceeds the use of the absorbed energy in photosynthesis. However, photoinhibition occurs at all light intensities with the same efficiency per photon. The aim of my thesis work was to build a model of photoinhibition that fits the experimental features of photoinhibition. I studied the role of electron transfer reactions of PSII in photoinhibition and found that changing the electron transfer rate had only minor influence on photoinhibition if light intensity was kept constant. Furthermore, quenching of antenna excitations protected less efficiently than it would protect if antenna chlorophylls were the only photoreceptors of photoinhibition. To identify photoreceptors of photoinhibition, I measured the action spectrum of photoinhibition. The action spectrum showed resemblance to the absorption spectra of Mn model compounds suggesting that the Mn cluster of OEC acts as a photoreceptor of photoinhibition under visible light, too. The role of Mn in photoinhibition was further supported by experiments showing that during photoinhibition OEC is damaged before electron transfer activity at the acceptor side of PSII is lost. Mn enzymes were found to be photosensitive under visible and UV light indicating that Mn-containing compounds, including OEC, are capable of functioning as photosensitizers both in visible and UV light. The experimental results above led to the Mn hypothesis of the mechanism of continuous-light-induced photoinhibition. According to the Mn hypothesis, excitation of Mn of OEC results in inhibition of electron donation from OEC to the oxidized primary donor P680+ both under UV and visible light. P680 is oxidized by photons absorbed by chlorophyll, and if not reduced by OEC, P680+ may cause harmful oxidation of other PSII components. Photoinhibition was also induced with intense laser pulses and it was found that the photoinhibitory efficiency increased in proportion to the square of pulse intensity suggesting that laser-pulse-induced photoinhibition is a two-photon reaction. I further developed the Mn hypothesis suggesting that the initial event in photoinhibition under both continuous and pulsed light is the same: Mn excitation that leads to the inhibition of electron donation from OEC to P680+. Under laser-pulse-illumination, another Mn-mediated inhibitory photoreaction occurs within the duration of the same pulse, whereas under continuous light, secondary damage is chlorophyll mediated. A mathematical model based on the Mn hypothesis was found to explain photoinhibition under continuous light, under flash illumination and under the combination of these two.

Effect of feeding level during autumn and winter on breeding weight and result in single and pair-housed minks

Selostus: Syys- ja talviruokinnan vaikutus yksin ja pareittain kasvatettujen minkkien lisääntymistulokseen

Calculation of wood volume and stem taper using terrestrial single-image close-range photogrammetry and contemporary software tools

Abstract

Euroopan yhteisen maksualueen (Single European payment area) vaikutukset maksuliikenteen tehokkuuteen case: Metso Oyj

Työn tavoitteena oli tutkia Euroopan yhteisen maksualueen (Single European Payment Area, SEPA) kehitystä ja selvittää mitä hyötyä siitä on Metso-konsernin maksuliikenteelle. Teoreettisessa osassa tarkastellaan mistä tehokas maksuliikenne koostuu ja esitetään SEPA:n kehitys peilaamalla sitä Berger et al.:n (1996) teoriasta muodostettuihin implikaatioihin. Empiirinen osuus sisältää kuvailevan Case-tutkimuksen, joka toteutettiin teemahaastatteluilla. Sitä täydennettiin kvantitatiivisella tilisiirtokustannusaineistolla (Metso-konserni). Tulosten mukaan SEPA-kehitys on sekä positiivista että negatiivista: 1) Jos kaikki maksuliikenteen osapuolet kokevat saavansa hyötyä uudistuksista, toteutuu sosiaalinen tehokkuus, jolloin kehitys nopeutuu ja kustannukset laskevat. Tämä on nähtävissä Metso-konsernin tilisiirtokustannusten kehityksestä. 2) SEPA lisää pankkien kustannuksia. 3) Järjestelmien kehitys vähentää maksuliikenneriskiä 4) Maksualuekehitys on vaarassa hidastua, jos alhaiseksi koetun riskin ehkäisemisestäei haluta maksaa.