Cyanobacteria from the Baltic Sea and Finnish lakes as an energy source and modulators of bioenergetic pathways

Cyanobacteria are a diverse group of oxygenic photosynthetic bacteria that inhabit in a wide range of environments. They are versatile and multifaceted organisms with great possibilities for different biotechnological applications. For example, cyanobacteria produce molecular hydrogen (H2), which is one of the most important alternatives for clean and sustainable energy. Apart from being beneficial, cyanobacteria also possess harmful characteristics and may become a source of threat to human health and other living organisms, as they are able to form surface blooms that are producing a variety of toxic or bioactive compounds. The University of Helsinki Culture Collection (UHCC) maintains around 1,000 cyanobacterial strains representing a large number of genera and species isolated from the Baltic Sea and Finnish lakes. The culture collection covers different life forms such as unicellular and filamentous, N2-fixing and non-N2-fixing strains, and planktonic and benthic cyanobacteria. In this thesis, the UHCC has been screened to identify potential strains for sustainable biohydrogen production and also for strains that produce compounds modifying the bioenergetic pathways of other cyanobacteria or terrestrial plants. Among the 400 cyanobacterial strains screened so far, ten were identified as high H2-producing strains. The enzyme systems involved in H2 metabolism of cyanobacteria were analyzed using the Southern hybridization approach. This revealed the presence of the enzyme nitrogenase in all strains tested, while none of them are likely to have contained alternative nitrogenases. All the strains tested, except for two Calothrix strains, XSPORK 36C and XSPORK 11A, were suggested to contain both uptake and bidirectional hydrogenases. Moreover, 55 methanol extracts of various cyanobacterial strains were screened to identify potent bioactive compounds affecting the photosynthetic apparatus of the model cyanobacterium, Synechocystis PCC 6803. The extract from Nostoc XPORK 14A was the only one that modified the photosynthetic machinery and dark respiration. The compound responsible for this effect was identified, purified, and named M22. M22 demonstrated a dual-action mechanism: production of reactive oxygen species (ROS) under illumination and an unknown mechanism that also prevailed in the dark. During summer, the Baltic Sea is occupied by toxic blooms of Nodularia spumigena (hereafter referred to as N. spumigena), which produces a hepatotoxin called nodularin. Long-term exposure of the terrestrial plant spinach to nodularin was studied. Such treatment resulted in inhibition of growth and chlorosis of the leaves. Moreover, the activity and amount of mitochondrial electron transfer complexes increased in the leaves exposed to nodularin-containing extract, indicating upregulation of respiratory reactions, whereas no marked changes were detected in the structure or function of the photosynthetic machinery. Nodularin-exposed plants suffered from oxidative stress, evidenced by oxidative modifications of various proteins. Plants initiated strategies to combat the stress by increasing the levels of alpha-tocopherol, mitochondrial alternative oxidase (AOX), and mitochondrial ascorbate peroxidase (mAPX).

Quest/ion of Identities in African American Feminist Postmodern Drama: A Study of Selected Plays by Suzan-Lori Parks

Innovative and unconventional, Pulitzer Prize-winning playwright Suzan-Lori Parks belongs to the continuum of African American playwrights who have contributed to the quest/ion – the quest for and question – of identities for African Americans. Her plays are sites in which the quest/ion of identities for African Americans is pursued, raised and enacted. She makes use of both page and stage to emphasize the exigency of reshaping African Americans’ identities through questioning the dominant ideologies and metanarratives, delegitimizing some of the prevailing stereotypes imposed on them, drawing out the complicity of the media in perpetuating racism, evoking slavery, lynching and their aftereffects, rehistoricizing African American history, catalyzing reflections on the various intersections of sex, race, class and gender orientations, and proffering alternative perspectives to help readers think more critically about issues facing African Americans. In my dissertation, I approach three plays by Parks – The Death of the Last Black Man in the Whole Entire World (1990), Venus (1996) and Fucking A (2000) – from the standpoints of postmodern drama and African American feminism with a focus on the terrains that reflect the quest/ion of identities for African Americans, especially African American women. I argue that postmodern drama and African American feminism provide the ground for Parks to promote the development of a political agenda in order to call into question a number of dominant ideologies and metanarratives with regard to African Americans and draw upon the roles of those metanarratives as a powerful apparatus of racial and sexual oppressions. I also explore how Parks engages with postmodern drama and African American feminism to incorporate her own mininarratives in the dominant discourses. I argue that Parks in these plays uses postmodern drama and African American feminism to encourage reflections on intersectionality in order to reveal the concerns of African Americans, particularly African American women. Her plays challenge the dominant order of hierarchy and patriarchy, while in some cases urging unity and solidarity between African American men and women by showing how unity and solidarity can help them confront race, class and gender oppressions. Furthermore, I discuss how the utilization of postmodern techniques and devices helps Parks to transform the conventional features of playwriting, to create incredulity toward the dominant systems of oppression and to incorporate her mininarratives within the context of dominant discourses.

Kaasunpolton tutkimuslaitteiston mittausten suunnittelu

Tämä diplomityö on Lappeenrannan teknillisessä yliopistossa aloitetun kaasunpolttotutkimushankkeen ensimmäinen tutkimusjakso. Tutkimushanketta varten on LTY:n voimalaitostekniikan koepolttolaboratoriossa rakennettu kaasunpolton tutkimuslaitteisto, jolla tässä diplomityössä perehdytään kaasuliekin lämpötilan mittausmenetelmiin, lämmönsiirtoon ja syntyviin päästöihin neste- ja maakaasupoltossa. Hankkeen toisessa tutkimusjaksossa laitteistolla tutkitaan regenaratiivista polttoa, ja polttoaineena käytetään neste- ja maakaasun lisäksi muita kaasuja kuten vetyä ja erilaisia seoskaasuja. Kaasunpolttotutkimushankkeen kokonaistavoitteena on pienentää kaasunpoltossa syntyviä NOx-päästöjä ja parantaa palamishyötysuhdetta ja tätä kautta pienentää laitteiston kokoa ja vähentää hiilidioksidipäästöjä.

Novel Proteins Involved in Dynamics of The Photosynthetic Apparatus

During the past few years, a considerable number of research articles have been published relating to the structure and function of the major photosynthetic protein complexes, photosystem (PS) I, PSII, cytochrome (Cyt) b6f, and adenosine triphosphate (ATP) synthase. Sequencing of the Arabidopsis thaliana (Arabidopsis) genome together with several high-quality proteomics studies has, however, revealed that the thylakoid membrane network of plant chloroplasts still contains a number of functionally unknown proteins. These proteins may have a role as auxiliary proteins guiding the assembly, maintenance, and turnover of the thylakoid protein complexes, or they may be as yet unknown subunits of the photosynthetic complexes. Novel subunits are most likely to be found in the NAD(P)H dehydrogenase (NDH) complex, the structure and function of which have remained obscure in the absence of detailed crystallographic data, thus making this thylakoid protein complex a particularly interesting target of investigation. In this thesis, several novel thylakoid-associated proteins were identified by proteomics-based methods. The major goal of characterization of the stroma thylakoid associated polysome-nascent chain complexes was to determine the proteins that guide the dynamic life cycle of PSII. In addition, a large protein complex of ≥ 1,000 kDa, residing in the stroma thylakoid, was characterized in greater depth and it was found to be a supercomplex composed of the PSI and NDH complexes. A set of newly identified proteins from Arabidopsis thylakoids was subjected to detailed characterization using the reverse genetics approach and extensive biochemical and biophysical analysis. The role of the novel proteins, either as auxiliary proteins or subunits of the photosynthetic protein complexes, was revealed. Two novel thylakoid lumen proteins, TLP18.3 and AtCYP38, function as auxiliary proteins assisting specific steps of the assembly/repair of PSII. The role of the 10-kDa thylakoid lumen protein PsbR is related to the optimization of oxygen evolution of PSII by assisting the assembly of the PsbP protein. Two integral thylakoid membrane proteins, NDH45 and NDH48, are novel subunits of the chloroplast NDH complex. Finally, the thylakoid lumen immunophilin AtCYP20-2 is suggested to interact with the NDH complex, instead of PSII as was hypothesized earlier.

Nuclear Matrix in Apoptotic Cell Death and Cell Proliferation. The role of Nuclear Mitotic Apparatus (NuMA) Protein

The nucleus is a membrane enclosed organelle containing most of the genetic information of the cell in the form of chromatin. The nucleus, which can be divided into many sub-organelles such as the nucleoli, the Cajal bodies and the nuclear lamina, is the site for several essential cellular functions such as the DNA replication and its regulation and most of the RNA synthesis and processing. The nucleus is often affected in disease: the size and the shape of the nucleus, the chromatin distribution and the size of the nucleoli have remained the basis for the grading of several cancers. The maintenance of the vertebrate body shape depends on the skeleton. Similarly, in a smaller context, the shape of the cell and the nucleus are mainly regulated by the cytoskeletal and nucleoskeletal elements. The nuclear matrix, which by definition is a detergent, DNase and salt resistant proteinaceous nuclear structure, has been suggested to form the nucleoskeleton responsible for the nuclear integrity. Nuclear mitotic apparatus protein, NuMA, a component of the nuclear matrix, is better known for its mitotic spindle organizing function. NuMA is one of the nuclear matrix proteins suggested to participate in the maintenance of the nuclear integrity during interphase but its interphase function has not been solved to date. This thesis study concentrated on the role of NuMA and the nuclear matrix as structural and functional components of the interphase nucleus. The first two studies clarified the essential role of caspase-3 in the disintegration of the nuclear structures during apoptosis. The second study also showed NuMA and chromatin to co-elute from cells in significant amounts and the apoptotic cleavage of NuMA was clarified to have an important role in the dissociation of NuMA from the chromatin. The third study concentrated on the interphase function of NuMA showing NuMA depletion to result in cell cycle arrest and the cytoplasmic relocalization of NuMA interaction partner GAS41. We suggest that the relocalization of the transcription factor GAS41 may mediate the cell cycle arrest. Thus, this study has given new aspects in the interactions of NuMA, chromatin and the nuclear matrix.

Transforming Bodies, Wandering Desires. Intra-actions of Gender and Sexuality in Non-heterosexual Transgender Embodiment

Pro gradu -tutkielmani käsittelee sukupuolen ja seksuaalisuuden keskinäisiä intraaktiivisia vuorovaikutussuhteita elettyjen, ei-heteroseksuaalisten transsukupuolisten ruumiiden kokemuksissa. Tutkielmani haastaa sukupuolen ja seksuaalisuuden pysyvyyden käsityksiä sekä niihin liittyviä yhteiskunnallisia normeja kuvaten tapoja, joilla seksuaalisuuden ja sukupuolen kokeminen ja käytännöt liikkuvat, kehittyvät ja vuorovaikuttavat eletyissä transsukupuolisuuden ruumiillistumissa. Haastattelen kuutta suomalaista, syntymässä naiseksi määriteltyä transsukupuolista henkilöä liittyen heidän kokemuksiinsa sukupuolesta, seksuaalisuudesta ja näiden muutoksista heidän tähänastisen elämänsä aikana. Tarkastelen nauhoitettuja ja litteroituja haastattelutekstejä transtutkimusta, queer-teoriaa ja feminististä uusmaterialistista filosofiaa yhdistävän teoreettisen kehyksen kautta keskittyen siihen, miten sukupuoli ja seksuaalisuus vaikuttavat toistensa kehitykseen, muutokseen ja materialisoitumiseen eri elämänvaiheissa ja tilanteissa. Erityisen tärkeiksi teoreettisiksi vaikuttajiksi tutkielmassani muodostuvat Judith Butlerin Gender Trouble (2006 [1990]) -teoksessaan hahmottelema performatiivisen sukupuolen teoria, Sara Ahmedin analyysi teoksessa Queer Phenomenology. Orientations, Objects, Others (2006) ja Karen Baradin teoksessa Meeting the Universe Halfway. Quantum Physics and the Entanglement of Matter and Meaning (2007) teoretisoima toimijuudellinen realismi. Päästäkseni kiinni sukupuolen ja seksuaalisuuden yhtymäkohtiin erittelen ensin niitä ominaisuuksia ja kokemuksia, jotka näyttäytyvät haastatteluteksteissäni oleellisina seksuaalisuuden ja sukupuolen kannalta. Tarkastelen seksuaalisuutta suuntautumisen, halun ja seksuaalisten käytäntöjen näkökulmasta: vaikka nämä seksuaalisuuden aspektit ovat kiinteästi kytköksissä toisiinsa, niitä ei voi kokonaan palauttaa toisiinsa. Sukupuolta käsittelen performatiivisuuden näkökulmasta painottaen transsukupuolisiin ruumiisiin ja niiden materiaalisuuteen liittyviä erityispiirteitä. Sukupuolen ja seksuaalisuuden suhteita toisiinsa tarkastelen sekä sellaisissa tilanteissa, joissa niitä on vaikea erottaa toisistaan, että sellaisissa, joissa niiden voidaan nähdä tuottavan toinentoisiaan. Tutkielmallani on etnografisia, filosofisia ja poliittisia ulottuvuuksia. Yhtäältä tahdon kuvata ja analysoida elettyjä transsukupuolisia kokemuksia ja tuottaa tietoa vähän tutkitun ihmisryhmän todellisuudesta. Toisaalta osallistun sukupuolifilosofiseen keskusteluun ruumiillisuudesta ja sukupuolen ja seksuaalisuuden olemuksesta. Lähestyn tutkimusprosessiani niin sanotusta transgender standpoint -näkökulmasta; kirjoitan transsukupuolisena ruumiina, transsukupuolisia ruumiita koskien, pyrkimyksenäni edistää elävien transsukupuolisten ruumiiden asemaa, toimijuutta ja näkyvyyttä yhteiskunnassa.

The Dynamics of Force Fluctuations in Shear Granular Flows

Tämän työn tavoitteena oli tutkia rakeisen materiaalin kinematiikkaa ja rakentaa koelaitteisto rakeisen materiaalin leikkausjännitysvirtauksien tutkimiseen. Kokeellisessa osassa on keskitytty sisäisiin voimaheilahteluihin ja niiden ymmärtämiseen. Teoriaosassa on käyty läpi rakeisen materiaalin yleisiä ominaisuuksia ja lisäksi on esitetty kaksi eri tapaa mallintaa fysikaalisien ominaisuuksien heilahteluja rakeisessa materiaalissa. Nämä kaksi esitettyä mallinnusmenetelmää ovat skalaarinen q-malli ja simulointi. Skalaarinen q-malli määrittelee jokaiseen yksittäiseen rakeeseen kohdistuvan jännityksen, rakeen ollessa osa 2- tai 3-dimensionaalista asetelmaa. Tämän mallin perusidea on kuvata jännityksien epähomogeenisuutta, joka johtuu rakeiden satunnaisasettelusta. Simulointimallinnus perustuu event-driven algoritmiin, missä systeemin dynamiikkaa kuvataan yksittäisillä partikkelien törmäyksillä. Törmäyksien vaiheet ratkaistiin käyttämällä liikemääräyhtälöitä ja restituution määritelmää. Teoriaosuudessa käytiin vielä pieniltä osin läpi syitä jännitysheilahteluihin ja rakeisen materiaalin lukkiintumiseen. Tutkimuslaitteistolla tutkittiin rakeisen materiaalin käyttäytymistä rengasmaisessa leikkausjännitysvirtauksessa. Tutkimusosuuden päätavoitteena oli mitata partikkelien kosketuksista ja törmäyksistä johtuvia hetkellisiä voimaheilahteluja rengastilavuuden pohjalta. Rakeisena materiaalina tutkimuksessa käytettiin teräskuulia. Jännityssignaali ajan funktiona osoittaa suurta heilahtelua, joka voi olla jopa kertalukua keskiarvosta suurempaa. Tällainen suuren amplitudin omaava heilahtelu on merkittävä haittapuoli yleisesti rakeisissa materiaaleissa käytettyjen jatkuvuusmallien kanssa. Tällainen heilahtelu tekee käytetyt jatkuvuusmallit epäpäteviksi. Yleisellä tasolla jännityksien todennäköisyysjakauma on yhtäpitävä skalaarisen q-mallin tuloksien kanssa. Molemmissa tapauksissa todennäköisyysjakaumalla on eksponentiaalinen muoto.

On the Analysis and Control of a Linear Synchronous Servomotor with a Flexible Load

Industry's growing need for higher productivity is placing new demands on mechanisms connected with electrical motors, because these can easily lead to vibration problems due to fast dynamics. Furthermore, the nonlinear effects caused by a motor frequently reduce servo stability, which diminishes the controller's ability to predict and maintain speed. Hence, the flexibility of a mechanism and its control has become an important area of research. The basic approach in control system engineering is to assume that the mechanism connected to a motor is rigid, so that vibrations in the tool mechanism, reel, gripper or any apparatus connected to the motor are not taken into account. This might reduce the ability of the machine system to carry out its assignment and shorten the lifetime of the equipment. Nonetheless, it is usually more important to know how the mechanism, or in other words the load on the motor, behaves. A nonlinear load control method for a permanent magnet linear synchronous motor is developed and implemented in the thesis. The purpose of the controller is to track a flexible load to the desired velocity reference as fast as possible and without awkward oscillations. The control method is based on an adaptive backstepping algorithm with its stability ensured by the Lyapunov stability theorem. As a reference controller for the backstepping method, a hybrid neural controller is introduced in which the linear motor itself is controlled by a conventional PI velocity controller and the vibration of the associated flexible mechanism is suppressed from an outer control loop using a compensation signal from a multilayer perceptron network. To avoid the local minimum problem entailed in neural networks, the initial weights are searched for offline by means of a differential evolution algorithm. The states of a mechanical system for controllers are estimated using the Kalman filter. The theoretical results obtained from the control design are validated with the lumped mass model for a mechanism. Generalization of the mechanism allows the methods derived here to be widely implemented in machine automation. The control algorithms are first designed in a specially introduced nonlinear simulation model and then implemented in the physical linear motor using a DSP (Digital Signal Processor) application. The measurements prove that both controllers are capable of suppressing vibration, but that the backstepping method is superior to others due to its accuracy of response and stability properties.

Electrochemical Characterisation of Filter Media Properties and Their Exploitation in Enhanced Filtration

Streaming potential measurements for the surface charge characterisation of different filter media types and materials were used. The equipment was developed further so that measurements could be taken along the surfaces, and so that tubular membranes could also be measured. The streaming potential proved to be a very useful tool in the charge analysis of both clean and fouled filter media. Adsorption and fouling could be studied, as could flux, as functions of time. A module to determine the membrane potential was also constructed. The results collected from the experiments conducted with these devices were used in the study of the theory of streaming potential as an electrokinetic phenomenon. Several correction factors, which are derived to take into account the surface conductance and the electrokinetic flow in very narrow capillaries, were tested in practice. The surface materials were studied using FTIR and the results compared with those from the streaming potentials. FTIR analysis was also found to be a useful tool in the characterisation of filters, as well as in the fouling studies. Upon examination of the recorded spectra from different depths in a sample it was possible to determine the adsorption sites. The influence of an external electric field on the cross flow microflltration of a binary protein system was investigated using a membrane electroflltration apparatus. The results showed that a significant improvement could be achieved in membrane filtration by using the measured electrochemical properties to help adjust the process conditions.

Characterization of Microparticle Retention Systems with Retention Process Analyzer

In the literature survey retention mechanisms, factors effecting retention and microparticles were studied. Also commercial microparticle retention systems and means to measure retention were studied. Optical retention measurement with RPA and Lasentec FBRM was studied. The experimental part contains study of different cationic polyacrylamides, anionic silica, bentonite and new generation micropolymer. In these studies the dosage, dosing order and dosing history were changing factors. The experimental work was done with RPA-apparatus with which, the retention process can be followed in real time. In testing was found that silica yielded better retention, when dosed nontraditionally before the polymer. Also silica was very dependant on the polymer dosage. With bentonite good colloidal retention was achieved with relatively low doses. Unlike silica bentonite was not dependant on polymer dosage. The relation of bentonite and polymer dosage is more defining when high retention is wanted. With 3-component systems using bentonite very high retention was achieved. With silica no improvement in retention was found in 3-component systems compared to dual component systems.

Fouling management and retention in nanofiltration of integrated paper mill effluents

Nanofiltration performance was studied with effluents from the pulp and paper industry and with model substances. The effect of filtration conditions and membrane properties on nanofiltration flux, retention, and fouling was investigated. Generally, the aim was to determine the parameters that influence nanofiltration efficiency and study how to carry out nanofiltration without fouling by controlling these parameters. The retentions of the nanofiltration membranes studied were considerably higher than those of tight ultrafiltration membranes, and the permeate fluxes obtained were approximately the same as those of tight ultrafiltration membranes. Generally, about 80% retentions of total carbon and conductivity were obtained during the nanofiltration experiments. Depending on the membrane and the filtration conditions, the retentions of monovalent ions (chloride) were between 80 and 95% in the nanofiltrations. An increase in pH improved retentions considerably and also the flux to some degree. An increase in pressure improved retention, whereas an increase in temperature decreased retention if the membrane retained the solute by the solution diffusion mechanism. In this study, more open membranes fouled more than tighter membranes due to higher concentration polarization and plugging of the membrane material. More irreversible fouling was measured for hydrophobic membranes. Electrostatic repulsion between the membrane and the components in the solution reduced fouling but did not completely prevent it with the hydrophobic membranes. Nanofiltration could be carried out without fouling, at least with the laboratory scale apparatus used here when the flux was below the critical flux. Model substances had a strong form of the critical flux, but the effluents had only a weak form of the critical flux. With the effluents, some fouling always occurred immediately when the filtration was started. However, if the flux was below the critical flux, further fouling was not observed. The flow velocity and pH were probably the most important parameters, along with the membrane properties, that influenced the critical flux. Precleaning of the membranes had only a small effect on the critical flux and retentions, but it improved the permeability of the membranes significantly.

Thylakoid Protein Phosphorylation in Regulation of Photosynthesis

Once the seed has germinated, the plant is forced to face all the environmental changes in its habitat. In order to survive, plants have evolved a number of different acclimation systems. The primary reaction behind plant growth and development is photosynthesis. Photosynthesis captures solar energy and converts it into chemical form. Photosynthesis in turn functions under the control of environmental cues, but is also affected by the growth, development, and metabolic state of a plant. The availability of solar energy fluctuates continuously, requiring non-stop adjustment of photosynthetic efficiency in order to maintain the balance between photosynthesis and the requirements and restrictions of plant metabolism. Tight regulation is required, not only to provide sufficient energy supply but also to prevent the damage caused by excess energy. The very first reaction of photosynthesis is splitting of water into the form of oxygen, hydrogen, and electrons. This most fundamental reaction of life is run by photosystem II (PSII), and the energy required for the reaction is collected by the light harvesting complex II (LHCII). Several proteins of the PSII-LHCII complex are reversibly phosphorylated according to the energy balance between photosynthesis and metabolism. Thylakoid protein phosphorylation has been under extensive investigation for over 30 years, yet the physiological role of phosphorylation remains elusive. Recently, the kinases behind the phosphorylation of PSII-LHCII proteins (STN7 and STN8) were identified and the knockout mutants of these kinases became available, providing powerful tools to elucidate the physiological role of PSII-LHCII phosphorylation. In my work I have used the stn7 and stn8 mutants in order to clarify the role of PSII-LHCII phosphorylation in regulation and protection of the photosynthetic machinery according to environmental cues. I show that STN7- dependent PSII-LHCII protein phosphorylation is required to balance the excitation energy distribution between PSII and PSI especially under low light intensities when the excitation energy transfer from LHC to PSII and PSI is efficient. This mechanism differs from traditional light quality-induced “state 1” – “state 2” transition and ensures fluent electron transfer from PSII to PSI under low light, yet having highest physiological relevance under fluctuating light intensity. STN8-dependent phosphorylation of PSII proteins, in turn, is required for fluent turn-over of photodamaged PSII complexes and has the highest importance upon prolonged exposure of the photosynthetic apparatus to excess light.

Novel Robot Solutions for Carrying out Field Joint Welding and Machining in the Assembly of the Vacuum Vessel of ITER

It is necessary to use highly specialized robots in ITER (International Thermonuclear Experimental Reactor) both in the manufacturing and maintenance of the reactor due to a demanding environment. The sectors of the ITER vacuum vessel (VV) require more stringent tolerances than normally expected for the size of the structure involved. VV consists of nine sectors that are to be welded together. The vacuum vessel has a toroidal chamber structure. The task of the designed robot is to carry the welding apparatus along a path with a stringent tolerance during the assembly operation. In addition to the initial vacuum vessel assembly, after a limited running period, sectors need to be replaced for repair. Mechanisms with closed-loop kinematic chains are used in the design of robots in this work. One version is a purely parallel manipulator and another is a hybrid manipulator where the parallel and serial structures are combined. Traditional industrial robots that generally have the links actuated in series are inherently not very rigid and have poor dynamic performance in high speed and high dynamic loading conditions. Compared with open chain manipulators, parallel manipulators have high stiffness, high accuracy and a high force/torque capacity in a reduced workspace. Parallel manipulators have a mechanical architecture where all of the links are connected to the base and to the end-effector of the robot. The purpose of this thesis is to develop special parallel robots for the assembly, machining and repairing of the VV of the ITER. The process of the assembly and machining of the vacuum vessel needs a special robot. By studying the structure of the vacuum vessel, two novel parallel robots were designed and built; they have six and ten degrees of freedom driven by hydraulic cylinders and electrical servo motors. Kinematic models for the proposed robots were defined and two prototypes built. Experiments for machine cutting and laser welding with the 6-DOF robot were carried out. It was demonstrated that the parallel robots are capable of holding all necessary machining tools and welding end-effectors in all positions accurately and stably inside the vacuum vessel sector. The kinematic models appeared to be complex especially in the case of the 10-DOF robot because of its redundant structure. Multibody dynamics simulations were carried out, ensuring sufficient stiffness during the robot motion. The entire design and testing processes of the robots appeared to be complex tasks due to the high specialization of the manufacturing technology needed in the ITER reactor, while the results demonstrate the applicability of the proposed solutions quite well. The results offer not only devices but also a methodology for the assembly and repair of ITER by means of parallel robots.

Functional characterization of proteins required for mitotic progression and the spindle assembly checkpoint

During mitotic cell division, the genetic material packed into chromosomes is divided equally between two daughter cells. Before the separation of the two copies of a chromosome (sister chromatids), each chromosome has to be properly connected with microtubules of the mitotic spindle apparatus and aligned to the centre of the cell. The spindle assembly checkpoint (SAC) monitors connections between microtubules and chromosomes as well as tension applied across the centromere. Microtubules connect to a chromosome via kinetochores, which are proteinaceous organelles assembled onto the centromeric region of the sister chromatids. Improper kinetochore-microtubule attachments activate the SAC and block chromosome segregation until errors are corrected and all chromosomes are connected to the mitotic spindle in a bipolar manner. The purpose of this surveillance mechanism is to prevent loss or gain of chromosomes in daughter cells that according to current understanding contributes to cancer formation. Numerous proteins participate in the regulation of mitotic progression. In this thesis, the mitotic tasks of three kinetochore proteins, Shugoshin 1 (Sgo1), INCENP, and p38 MAP kinase (p38 MAPK), were investigated. Sgo1 is a protector of centromeric cohesion. It is also described in the tension-sensing mechanism of the SAC and in the regulation of kinetochore-microtubule connections. Our results revealed a central role for Sgo1 in a novel branch of kinetochore assembly. INCENP constitutes part of the chromosomal passenger complex (CPC). The other members of the core complex are the Aurora B kinase, Survivin and Borealin. CPC is an important regulatory element of cell division having several roles at various stages of mitosis. Our results indicated that INCENP and Aurora B are highly dynamic proteins at the mitotic centromeres and suggested a new role for CPC in regulation of chromosome movements and spindle structure during late mitosis. The p38 MAPK has been implicated in G1 and G2 checkpoints during the cell cycle. However, its role in mitotic progression and control of SAC signaling has been controversial. In this thesis, we discovered a novel function for p38γ MAPK in chromosome orientation and spindle structure as well as in promotion of viability of mitotic cells.