Messerschmitt Bf-109 Suomen ja Unkarin ilmavoimissa vuosina 1942 - 1945

Tämä laadullinen sotahistorian tutkimus käsittelee ja vertailee Messerschmitt Bf-109 -konetyypin käyttöä Suomessa ja Unkarissa toisen maailmansodan aikana. Tutkimusmenetelmänä on käytetty vertailevaa (komparatiivista) aineistoanalyysia. Suomen ja Unkarin ilmavoimat ovat tutkimuksen kohdemaita, ja tutkimuksessa perehdytään Messerschmitthävittäjän käyttöperiaatteisiin, konemallin taktiseen käyttöön, sekä lentäjien koulutukseen. Lisäksi perehdytään laivueiden ja yksittäisten lentäjien taistelukertomuksien kautta siihen, millainen konemalli oli lentää ilmataisteluissa. Tutkielmassa pyritään vastaamaan pääkysymykseen: Mitkä olivat Messerschmitt Bf-109:n käyttöperiaatteet Suomen ja Unkarin ilmavoimissa toisen maailmansodan aikana? Pääkysymystä tukevat seuraavat alatutkimuskysymykset: Miten lentäjiä koulutettiin kyseiseen konetyyppiin? Miten Messerschmitthävittäjät ryhmitettiin kohdemaiden sodan ajan organisaatioissa? Mitä viholliskalustoa vastaan Messerschmitthävittäjiä käytettiin itärintamalla? Mitä eroja ja samankaltaisuuksia ilmenee Suomen ja Unkarin hävittäjätaktiikassa Messerschmitt Bf-109:n kohdalla ja miksi? Miten näissä maissa toimintaympäristöt erosivat /muistuttivat toisiaan? Tutkielman johdannossa esitellään tutkimuksen päämäärä, rajaus, tutkimuskysymykset, viitekehys sekä lyhyesti tutkimuksen aiheena oleva Messerschmitt Bf-109 -hävittäjä. Ensimmäisessä pääluvussa käsitellään Bf-109:n käyttöä Suomessa aina hävittäjähankinnasta taktiik-kaan ja koulutukseen. Toisessa pääluvussa käsitellään vastaavasti Bf-109:n käyttöä Unkarin ilmavoimissa samalla logiikalla. Johtopäätösluvussa esitellään tutkimustulokset ja johtopäätökset, joilla vastataan tutkimuskysymyksiin. Tutkimuksen tuloksina todetaan että isoimmat käyttöperiaatteelliset erot Suomen ja Unkarin välillä liittyivät hankintaan ja koulutukseen ja taistelutapaan, kun taas samankaltaisuuksia oli havaittavissa konekaluston sijoittelussa ja toimintaympäristöissä. Unkari sai geopoliittisen asemansa ansiosta enemmän tukea saksalaiselta Luftwaffe:lta, kun taas esimerkiksi varaosien saaminen Suomeen oli usein vaikeaa.

Free Flap Monitoring. Using Tissue Oxygen Measurement and Positron Emission Tomography

Aims:This study was carried out to evaluate the feasibility of two different methods to determine free flap perfusion in cancer patients undergoing major reconstructive surgery. The hypotheses was that low perfusion in the flap is associated with flap complications. Patients and methods: Between August 2002 and June 2008 at the Department of Otorhinolaryngology – Head and Neck Surgery, Department of Surgery, and at the PET Centre, Turku, 30 consecutive patients with 32 free flaps were included in this study. The perfusion of the free microvascular flaps was assessed with positron emission tomography (PET) and radioactive water ([¹⁵O] H₂O) in 40 radiowater injections in 33 PET studies. Furthermore, 24 free flaps were monitored with a continuous tissue oxygen measurement using flexible polarographic catheters for an average of three postoperative days. Results: Of the 17 patients operated on for head and neck (HN) cancer and reconstructed with 18 free flaps, three re-operations were carried out due to poor tissue oxygenation as indicated by p_tiO₂ monitoring results and three other patients were reoperated on for postoperative hematomas in the operated area. Blood perfusion assessed with PET (BF_PET) was above 2.0 mL / min / 100 g in all flaps and a low flap-to-muscle BFPET ratio appeared to correlate with poor survival of the flap. Survival in this group of HN cancer patients was 9.0 months (median, range 2.4-34.2) after a median follow-up of 11.9 months (range 1.0-61.0 months). Seven HN patients of this group are alive without any sign of recurrence and one patient has died of other causes. All of the 13 breast reconstruction patients included in the study are alive and free of disease at a median follow-up time of 27.4 months (range 13.9-35.7 months). Re-explorations were carried out in three patients due data provided by p_tiO₂ monitoring and one re-exploration was avoided on the basis of adequate blood perfusion assessed with PET. Two patients had donorsite morbidity and 3 patients had partial flap necrosis or fat necrosis. There were no total flap losses. Conclusions: P_tiO₂ monitoring is a feasible method of free flap monitoring when flap temperature is monitored and maintained close to the core temperature. When other monitoring methods give controversial results or are unavailable, [₁₅O] H₂O PET technique is feasible in the evaluation of the perfusion of the newly reconstructed free flaps.

Imaging of Tumour Microenvironment for the Planning of Oncological Therapies Using Positron Emission Tomography

Tumour cells differ from normal tissue cells in several important ways. These differences, like for example changed energy metabolism, result in altered microenvironment of malignant tumours. Non-invasive imaging of tumour microenvironment has been at the centre of intense research recently due to the important role that this changed environement plays in the development of malignant tumours and due to the role it plays in the treatment of these tumours. In this respect, perhaps the most important characteristics of the tumour microenvironment from this point of view are the lack of oxygen or hypoxia and changes in blood flow (BF). The purpose of this thesis was to investigate the processes of energy metabolism, BF and oxygenation in head and neck cancer and pancreatic tumours and to explore the possibilities of improving the methods for their quantification using positron emission tomography (PET). To this end [18F]EF5, a new PET tracer for detection of tumour hypoxia was investigated. Favourable uptake properties of the tracer were observed. In addition, it was established that the uptake of this tracer does not correlate with the uptake of existing tracers for the imaging of energy metabolism and BF, so the information about the presence of tissue hypoxia cannot therefore be obtained using tracers such as [18F]FDG or [15O]H2O. These results were complemented by the results of the follow-up study in which it was shown that the uptake of [18F]EF5 in head and neck tumours prior to treatment is also associated with the overall survival of the patients, indicating that tumour hypoxia is a negative prognostic factor and might be associated with therapeutic resistance. The influences of energy metabolism and BF on the survival of patients with pancreatic cancer were investigated in the second study. The results indicate that the best predictor of survival of patients with pancreatic cancer is the relationship between energy metabolism and BF. These results suggest that the cells with high metabolic activity in a hypoperfused tissue have the most aggressive phenotype.

Towards sustainable Iron- and steelmaking with economic optimization

The iron and steelmaking industry is among the major contributors to the anthropogenic emissions of carbon dioxide in the world. The rising levels of CO2 in the atmosphere and the global concern about the greenhouse effect and climate change have brought about considerable investigations on how to reduce the energy intensity and CO2 emissions of this industrial sector. In this thesis the problem is tackled by mathematical modeling and optimization using three different approaches. The possibility to use biomass in the integrated steel plant, particularly as an auxiliary reductant in the blast furnace, is investigated. By pre-processing the biomass its heating value and carbon content can be increased at the same time as the oxygen content is decreased. As the compression strength of the preprocessed biomass is lower than that of coke, it is not suitable for replacing a major part of the coke in the blast furnace burden. Therefore the biomass is assumed to be injected at the tuyere level of the blast furnace. Carbon capture and storage is, nowadays, mostly associated with power plants but it can also be used to reduce the CO2 emissions of an integrated steel plant. In the case of a blast furnace, the effect of CCS can be further increased by recycling the carbon dioxide stripped top gas back into the process. However, this affects the economy of the integrated steel plant, as the amount of top gases available, e.g., for power and heat production is decreased. High quality raw materials are a prerequisite for smooth blast furnace operation. High quality coal is especially needed to produce coke with sufficient properties to ensure proper gas permeability and smooth burden descent. Lower quality coals as well as natural gas, which some countries have in great volumes, can be utilized with various direct and smelting reduction processes. The DRI produced with a direct reduction process can be utilized as a feed material for blast furnace, basic oxygen furnace or electric arc furnace. The liquid hot metal from a smelting reduction process can in turn be used in basic oxygen furnace or electric arc furnace. The unit sizes and investment costs of an alternative ironmaking process are also lower than those of a blast furnace. In this study, the economy of an integrated steel plant is investigated by simulation and optimization. The studied system consists of linearly described unit processes from coke plant to steel making units, with a more detailed thermodynamical model of the blast furnace. The results from the blast furnace operation with biomass injection revealed the importance of proper pre-processing of the raw biomass as the composition of the biomass as well as the heating value and the yield are all affected by the pyrolysis temperature. As for recycling of CO2 stripped blast furnace top gas, substantial reductions in the emission rates are achieved if the stripped CO2 can be stored. However, the optimal recycling degree together with other operation conditions is heavily dependent on the cost structure of CO2 emissions and stripping/storage. The economical feasibility related to the use of DRI in the blast furnace depends on the price ratio between the DRI pellets and the BF pellets. The high amount of energy needed in the rotary hearth furnace to reduce the iron ore leads to increased CO2 emissions.