Developmental changes in the heavy subunit of neurofilaments in the corpus callosum of the cat.

In the corpus callosum of the cat, the heavy subunit of neurofilaments (NFH) can be demonstrated with the monoclonal antibody NE14, as early as P11, not at P3, and only in a few axons. At P18-19 and more markedly at P29, many more callosal axons have become positive to NE14 and this is similar to what is found in the adult. In contrast, callosal axons become positive to the neurofilament antibody SMI-32 only between P29 and P39 and remain positive in the adult. Treatment with alkaline phosphatase prevents axonal staining with NE14, but results in SMI-32 staining of a few callosal axons as early as P11, but not at P3. Between P11 and P19 the number of axons stained with SMI-32 after alkaline phosphatase treatment increases, in parallel with that of axons stained with NE14. Thus NE14 appears to recognize a phosphorylated form of NFH, while SMI-32 appears to recognize an epitope of NFH which is either masked by phosphate or inaccessible until between P29 and P39, unless the tissue is treated with alkaline phosphatase. These two forms of NFH appear towards the end of the period of massive developmental elimination of callosal axons. They are also synchronous with changes in the spacing of neurofilaments quantified in a separate ultrastructural study. These cytoskeletal changes may terminate the juvenile-labile state of callosal axons and allow further axial growth of the axon.

The relationship between virtual body ownership and temperature sensitivity.

In the rubber hand illusion tactile stimulation seen on a rubber hand, that is synchronous with tactile stimulation felt on the hidden real hand, can lead to an illusion of ownership over the rubber hand. This illusion has been shown to produce a temperature decrease in the hidden hand, suggesting that such illusory ownership produces disownership of the real hand. Here we apply immersive virtual reality (VR) to experimentally investigate this with respect to sensitivity to temperature change. Forty participants experienced immersion in a VR with a virtual body (VB) seen from a first person perspective. For half the participants the VB was consistent in posture and movement with their own body, and in the other half there was inconsistency. Temperature sensitivity on the palm of the hand was measured before and during the virtual experience. The results show that temperature sensitivity decreased in the consistent compared to the inconsistent condition. Moreover, the change in sensitivity was significantly correlated with the subjective illusion of virtual arm ownership but modulated by the illusion of ownership over the full virtual body. This suggests that a full body ownership illusion results in a unification of the virtual and real bodies into one overall entity - with proprioception and tactile sensations on the real body integrated with the visual presence of the virtual body. The results are interpreted in the framework of a"body matrix" recently introduced into the literature.

Identification of neuronal network properties from the spectral analysis of calcium imaging signals in neuronal cultures

Neuronal networks in vitro are prominent systems to study the development of connections in living neuronal networks and the interplay between connectivity, activity and function. These cultured networks show a rich spontaneous activity that evolves concurrently with the connectivity of the underlying network. In this work we monitor the development of neuronal cultures, and record their activity using calcium fluorescence imaging. We use spectral analysis to characterize global dynamical and structural traits of the neuronal cultures. We first observe that the power spectrum can be used as a signature of the state of the network, for instance when inhibition is active or silent, as well as a measure of the network's connectivity strength. Second, the power spectrum identifies prominent developmental changes in the network such as GABAA switch. And third, the analysis of the spatial distribution of the spectral density, in experiments with a controlled disintegration of the network through CNQX, an AMPA-glutamate receptor antagonist in excitatory neurons, reveals the existence of communities of strongly connected, highly active neurons that display synchronous oscillations. Our work illustrates the interest of spectral analysis for the study of in vitro networks, and its potential use as a network-state indicator, for instance to compare healthy and diseased neuronal networks.

Drift and ownership toward a distant virtual body.

In body ownership illusions participants feel that a mannequin or virtual body (VB) is their own. Earlier results suggest that body ownership over a body seen from behind in extra personal space is possible when the surrogate body is visually stroked and tapped on its back, while spatially and temporal synchronous tactile stimulation is applied to the participant's back. This result has been disputed with the claim that the results can be explained by self-recognition rather than somatic body ownership. We carried out an experiment with 30 participants in a between-groups design. They all saw the back of a VB 1.2 m in front, that moved in real-time determined by upper body motion capture. All felt tactile stimulation on their back, and for 15 of them this was spatially and temporally synchronous with stimulation that they saw on the back of the VB, but asynchronous for the other 15. After 3 min a revolving fan above the VB descended and stopped at the position of the VB neck. A questionnaire assessed referral of touch to the VB, body ownership, the illusion of drifting forwards toward the VB, and the VB drifting backwards. Heart rate deceleration (HRD) and the amount of head movement during the threat period were used to assess the response to the threat from the fan. Results showed that although referral of touch was significantly greater in the synchronous condition than the asynchronous, there were no other differences between the conditions. However, a further multivariate analysis revealed that in the visuotactile synchronous condition HRD and head movement increased with the illusion of forward drift and decreased with backwards drift. Body ownership contributed positively to these drift sensations. Our conclusion is that the setup results in a contradiction-somatic feelings associated with a distant body-that the brain attempts to resolve by generating drift illusions that would make the two bodies coincide.

Is my hand connected to my body? The impact of body continuity and arm alignment on the virtual hand illusion

When a rubber hand is placed on a table top in a plausible position as if part of a person"s body, and is stroked synchronously with the person"s corresponding hidden real hand, an illusion of ownership over the rubber hand can occur (Botvinick and Cohen 1998). A similar result has been found with respect to a virtual hand portrayed in a virtual environment, a virtual hand illusion (Slater et al. 2008). The conditions under which these illusions occur have been the subject of considerable study. Here we exploited the flexibility of virtual reality to examine four contributory factors: visuo-tactile synchrony while stroking the virtual and the real arms, body continuity, alignment between the real and virtual arms, and the distance between them. We carried out three experiments on a total of 32 participants where these factors were varied. The results show that the subjective illusion of ownership over the virtual arm and the time to evoke this illusion are highly dependent on synchronous visuo-tactile stimulation and on connectivity of the virtual arm with the rest of the virtual body. The alignment between the real and virtual arms and the distance between these were less important. It was found that proprioceptive drift was not a sensitive measure of the illusion, but was only related to the distance between the real and virtual arms.

Decrease in luteinizing hormone pulse frequency during a five-hour peripheral Ghrelin infusion in the ovariectomized rhesus monkey

RESUME : La ghrelin est un peptide sécrété par l'estomac jouant un rôle important dans le maintien de l'homéostasie énergétique. Ses taux plasmatiques sont augmentés durant des périodes prolongées de déficit nutritionnel. Une carence énergétique étant souvent associée à une inhibition de l'axe hypothalamo-hypophyso-ovarien, nous avons postulé que l'augmentation des taux circulant de ghrelin pourrait diminuer l'activité du générateur hypothalamique de pulsations de GnRH. Le protocole expérimental impliquait des singes rhésus adultes ovariectomisés (n=6) qui dans un premier temps recevaient durant 3 heures une perfusion de solution saline physiologique afin de mesurer la sécrétion pulsatile de LH à l'état basai. L'expérience se poursuivait alors durant 5 heures par une perfusion intraveineuse de ghrelin humaine (un bolus de 100-150µg suivi par 100-150µg/h) ou le maintien de la perfusion de solution saline physiologique. Des échantillons de sang étaient prélevés toutes les 15 minutes. La perfusion de ghrelin a augmenté ses taux plasmatiques de 2.9 fois par rapport aux valeurs de base. L'administration de ghrelin a significativement diminué la fréquence des pulsations de LH (de 0.89±0.07/h à l'état basai à 0.57±0.10/h durant la perfusion de ghrelin; p<0.05, moyenne±SEM), alors que la fréquence des pulsations de LH est restée inchangée durant la perfusion de solution physiologique. L'amplitude des pulsations de LH n'a pas été modifiée. La ghrelin a également stimulé de manière significative la sécrétion de cortisol et d'hormone de croissance, mais n'a toutefois pas eu d'effet sur la sécrétion de leptin. En conclusion, la ghrelin peut inhiber l'activité du générateur de pulsations de GnRH et pourrait ainsi contribuer à l'inhibition de l'axe de la reproduction observée durant des périodes de carence nutritionnelle, comme notamment chez les patientes souffrant d'anorexie mentale. La ghrelin peut également activer l'axe hypothalamo-hypophyso-surrénalien. Le lien dans cette situation entre l'activation de l'axe surrénalien et l'inhibition de l'axe de la reproduction reste à démontrer. ABSTRACT: Ghrelin, a nutrition-related peptide secreted by the stomach, is elevated during prolonged food deprivation. Because undernutrition is often associated with a suppressed reproductive axis, we have postulated that increasing peripheral ghrelin levels will decrease the activity of the GnRH pulse generator. Adult ovariectomized rhesus monkeys (n = 6) were subjected to a 5-h iv human ghrelin (100- to 150µg bolus followed by 100-150 µg/h) or saline infusion, preceded by a 3-h saline infusion to establish baseline pulsatile LH release. Blood samples were collected at 15-min intervals throughout the experiment. Ghrelin infusion increased plasma ghrelin levels 2.9-fold of baseline. Ghrelin significantly decreased LH pulse frequency (from 0.89 ± 0.07/h in baseline to 0.57 ± 0.10/h during ghrelin infusion; P<0.05, mean ± SEM), whereas LH pulse frequency remained unchanged during saline treatment. LH pulse amplitude was not affected. Ghrelin also significantly stimulated both Cortisol and GH release, but had no effect on leptin. We conclude that ghrelin can inhibit GnRH pulse activity and may thereby mediate the suppression of the reproductive system observed in conditions of undernutrition, such as in anorexia nervosa. Ghrelin also activates the adrenal axis, but the relevance of this to the inhibition of GnRH pulse frequency remains to be established.

Designing Digital Filters for Servo Systems

The aim of this work was to select an appropriate digital filter for a servo application and to filter the noise from the measurement devices. Low pass filter attenuates the high frequency noise beyond the specified cut-off frequency. Digital lowpass filters in both IIR and FIR responses were designed and experimentally compared to understand their characteristics from the corresponding step responses of the system. Kaiser Windowing and Equiripple methods were selected for FIR response, whereas Butterworth, Chebyshev, InverseChebyshev and Elliptic methods were designed for IIR case. Limitations in digital filter design for a servo system were analysed. Especially the dynamic influences of each designed filter on the control stabilityof the electrical servo drive were observed. The criterion for the selection ofparameters in designing digital filters for servo systems was studied. Control system dynamics was given significant importance and the use of FIR and IIR responses in different situations were compared to justify the selection of suitableresponse in each case. The software used in the filter design was MatLab/Simulink® and dSPACE's DSP application. A speed controlled Permanent Magnet Linear synchronous Motor was used in the experimental work.

Drift and ownership toward a distant virtual body.

In body ownership illusions participants feel that a mannequin or virtual body (VB) is their own. Earlier results suggest that body ownership over a body seen from behind in extra personal space is possible when the surrogate body is visually stroked and tapped on its back, while spatially and temporal synchronous tactile stimulation is applied to the participant's back. This result has been disputed with the claim that the results can be explained by self-recognition rather than somatic body ownership. We carried out an experiment with 30 participants in a between-groups design. They all saw the back of a VB 1.2 m in front, that moved in real-time determined by upper body motion capture. All felt tactile stimulation on their back, and for 15 of them this was spatially and temporally synchronous with stimulation that they saw on the back of the VB, but asynchronous for the other 15. After 3 min a revolving fan above the VB descended and stopped at the position of the VB neck. A questionnaire assessed referral of touch to the VB, body ownership, the illusion of drifting forwards toward the VB, and the VB drifting backwards. Heart rate deceleration (HRD) and the amount of head movement during the threat period were used to assess the response to the threat from the fan. Results showed that although referral of touch was significantly greater in the synchronous condition than the asynchronous, there were no other differences between the conditions. However, a further multivariate analysis revealed that in the visuotactile synchronous condition HRD and head movement increased with the illusion of forward drift and decreased with backwards drift. Body ownership contributed positively to these drift sensations. Our conclusion is that the setup results in a contradiction-somatic feelings associated with a distant body-that the brain attempts to resolve by generating drift illusions that would make the two bodies coincide.

Primääri-sekundäärivuodon tunnistaminen aktiivisuusmittauksin Loviisan voimalaitoksella

Diplomityössä tutkittiin Loviisan voimalaitoksen primääri- ja sekundääripiirin aktiivisuusmittausten kykyä tunnistaa pienet primääri-sekundäärivuodot. Tarkasteltavat primääri-sekundäärivuotojen suuruudet valittiin laitoksen hätätilanne- ja häiriönselvitysohjeiden mukaisesti. Vuodon vaikutuksia arvioitiin erilaisilla primäärijäähdytteen ominaisaktiivisuuksilla. Ominaisaktiivisuudet primääripiirissä määritettiin nuklidikohtaisesti erilaisille polttoainevuototapauksille. Työssä huomioitiin myös transienteissa mahdollisesti esiintyvä primääripiirin aktiivisuustasoa nostava spiking-ilmiö. Vuodon tarkempaa tunnistamista varten työssä laskettiin tarkasteltaville mittareille kalibrointikertoimet. Primääri-sekundäärivuoto mallinnettiin APROS-simulointiohjelmalla laitoksen eri käyttötiloissa ja kahdella eri vuotokoolla. Varsinainen aktiivisuuslaskenta suoritettiin SEKUN-ohjelmalla. Työssä tätä aktiivisuus- ja päästölaskentaohjelmaa muokattiin ohjelmoimalla siihen tarkasteltavat aktiivisuusmittaukset sekä primääripiirin puhdistus ja ulospuhallus. Laskelmien tuloksena saatiin arviot kunkin tarkasteltavana olleen aktiivisuusmittauksen soveltuvuudesta primääri-sekundäärivuodon tunnistamiseen erilaisissa polttoainevuototapauksissa ja reaktorin eri tehotasoilla. Häiriönselvitysohje I3:n käyttöönottoa edellyttävät vuotokoot määritettiin aktiivisuusmittausten havaitseman perusteella. Erityisesti kuumavalmiustilassa tapauksissa, joissa reaktorisydämessä oletetaan olevan tiiveytensä menettäneitä polttoainesauvoja, spikingin vaikutus jäähdytteiden aktiivisuuspitoisuuksiin ja mittaustuloksiin oli merkittävä. Niiltä osin, kuin tulokset käsittelevät ohjeissa vuodon tunnistamiseen käytettyjä aktiivisuusrajoja, tulokset osoittivat aktiivisuusrajat oikeiksi. Kuumavalmiudessa aktiivisuusmittausten mittausalueet saattavat joissakin tapauksissa rajoittaa primääri-sekundäärivuodon tunnistamista.

Optimisation of data analysis method for a fluidized bed combustion test rig

Nowadays the used fuel variety in power boilers is widening and new boiler constructions and running models have to be developed. This research and development is done in small pilot plants where more faster analyse about the boiler mass and heat balance is needed to be able to find and do the right decisions already during the test run. The barrier on determining boiler balance during test runs is the long process of chemical analyses of collected input and outputmatter samples. The present work is concentrating on finding a way to determinethe boiler balance without chemical analyses and optimise the test rig to get the best possible accuracy for heat and mass balance of the boiler. The purpose of this work was to create an automatic boiler balance calculation method for 4 MW CFB/BFB pilot boiler of Kvaerner Pulping Oy located in Messukylä in Tampere. The calculation was created in the data management computer of pilot plants automation system. The calculation is made in Microsoft Excel environment, which gives a good base and functions for handling large databases and calculations without any delicate programming. The automation system in pilot plant was reconstructed und updated by Metso Automation Oy during year 2001 and the new system MetsoDNA has good data management properties, which is necessary for big calculations as boiler balance calculation. Two possible methods for calculating boiler balance during test run were found. Either the fuel flow is determined, which is usedto calculate the boiler's mass balance, or the unburned carbon loss is estimated and the mass balance of the boiler is calculated on the basis of boiler's heat balance. Both of the methods have their own weaknesses, so they were constructed parallel in the calculation and the decision of the used method was left to user. User also needs to define the used fuels and some solid mass flowsthat aren't measured automatically by the automation system. With sensitivity analysis was found that the most essential values for accurate boiler balance determination are flue gas oxygen content, the boiler's measured heat output and lower heating value of the fuel. The theoretical part of this work concentrates in the error management of these measurements and analyses and on measurement accuracy and boiler balance calculation in theory. The empirical part of this work concentrates on the creation of the balance calculation for the boiler in issue and on describing the work environment.

Development of a simulation tool for torsional vibration of branched power transmission system

In this master's thesis a mechanical model that is driven with variable speed synchronous machine was developed. The developed mechanical model simulates the mechanics of power transmission and its torsional vibrations. The mechanical model was developed for the need of the branched mechanics of a rolling mill and the propulsion system of a tanker. First, the scope of the thesis was to clarify the concepts connected to the mechanical model. The clarified concepts are the variable speed drive, the mechanics of power transmission and the vibrationsin the power transmission. Next, the mechanical model with straight shaft line and twelve moments of inertia that existed in the beginning was developed to be branched considering the case of parallel machines and the case of parallel rolls. Additionally, the model was expanded for the need of moreaccurate simulation to up to thirty moments of inertia. The model was also enhanced to enable three phase short circuit situation of the simulated machine. After that the mechanical model was validated by comparing the results of the developed simulation tool to results of other simulation tools. The compared results are the natural frequencies and mode shapes of torsional vibration, the response of the load torque step and the stress in the mechanical system occurred by the permutation of the magnetic field that is arisen from the three phase short circuit situation. The comparisons were accomplished well and the mechanical model was validated for the compared cases. Further development to be made is to develop the load torque to be time-dependent and to install two frequency converters and two FEM modeled machines to be simulated parallel.

Automating The User Interface Implementation Process by Code Generation

3G-radioverkon asetusten hallinnointi suoritetaan säätämällä radioverkkotietokantaan talletettavia parametreja. Hallinnointiohjelmistossa tuhannetradioverkon parametrit näkyvät käyttöliittymäkomponentteina, joita ohjelmiston kehityskaaressa jatkuvasti lisätään, muutetaan ja poistetaan asiakkaan tarpeidenmukaan. Parametrien lisäämisen toteutusprosessi on ohjelmistokehittäjälle työlästä ja mekaanista. Diplomityön tavoitteeksi asetettiin kehittää koodigeneraattori, joka luo kaiken toteutusprosessissa tuotetun koodin automaattisesti niistä määrittelyistä, jotka ovat nykyäänkin saatavilla. Työssä kehitetty generaattori nopeuttaa ohjelmoijan työtä eliminoimalla yhden aikaa vievän ja mekaanisen työvaiheen. Seurauksena saadaan yhtenäisempää ohjelmistokoodia ja säästetään yrityksen ohjelmistotuotannon kuluissa, kun ohjelmoijan taito voidaan keskittää vaativimpiin tehtäviin.

Napakäämityn murtovakokestomagneettitahtikoneen suunnittelu

Diplomityössä tutustutaan napakäämittyihin murtovakokestomagneettitahtikoneisiin sekä syvennytään niiden suunnitteluun analyyttisen laskennanavulla. Analyyttisen laskennan haasteena on perinteisesti käytettyjen kestomagneettitahtikoneiden laskentayhtälöiden sovittaminen murtovakokäämityille kestomagneettitahtikoneille. Työn lopussa analyyttisen laskennan tuloksia verrataan kenttälaskentaohjelmalla saatuihin tuloksiin. Tärkeimmät analyyttiset yhtälöt sekä laskentamallin rakenne on esitetty työssä.

Höyrynkestävän eristerakenteen suunnittelu sähkökoneen staattoriin

Perinteiset sähkökoneen eristemateriaalit eivät kestä vesihöyryä. Vesihöyryä kestävä eristerakenne on tarpeen, kun tehdään hermeettinen turbogeneraattori, jossa vesihöyry virtaa ilmavälin läpi. Tällainen turbogeneraattori mahdollistaa teholtaan tavallista pienemmän biopolttoainevoimalan rakentamisen kustannustehokkaasti. Työssä tutkittiin erilaisia pyörölankakäämityn pienjännitekoneen eristemateriaaleja. Pienoismallikokein testattiin ne eristemateriaalit, joiden uskottiin kirjallisuustietojen perusteella selviytyvän vesihöyryssä. Myös perinteinen, polyesteriin pohjautuva eristerakenne testattiin. Kokeiden perusteella valittiin turbogeneraattorin staattoriin sopiva eristerakenne.

Plasmapolttoprosessin kehittäminen ja optimointi

Ydinvoimaloidenprimaarivesikierron puhdistukseen käytetään ioninvaihtohartsia. Käytönjälkeen ioninvaihtohartsi luokitellaan matalaja keskiaktiivisiin jätteisiin. Plasmakäsittelyllä käytetyn ioninvaihtohartsin tilavuutta voidaan pienentää sekä sen orgaaninen luonne poistaa. Plasmakäsittelyn tarkoituksena on hapettaa orgaaninen aines oksideiksi, jotka poistuvat prosessista savukaasuina. Epäorgaaninen aines, joka sisältää radioaktiivisen aineksen, on tarkoitus hapettaa oksideiksi ja sulfideiksi, jotka voidaan kerätä talteen tuhkana. Tässä diplomityössä käsitellään käytetyn ioninvaihtohartsin käsittelyyn suunnitellun plasmapolttoprosessin kehittämistä ja optimointia. Ioninvaihtohartsin plasmakäsittelyssä syntyvien reaktiotuotteiden selvittäminen suoritettiin tarkastelemalla ainetaseita sekä aihetta käsitteleviä tutkimuksia. Näiden perusteella parannettiin jäähdytystä, suunniteltiin jatkuvatoiminen syöttömenetelmä sekä laadittiin toimintaalueen reunaehdot laitteistolle. Koelaitteistossa 6,5 kW:n rfteho syötetään sovitinpiirin ja kuparisen induktiokelan kautta plasmaan. Plasmakaasuna on käytetty hapenja argonin seoskaasua. Plasmapolttoa on seurattu massaspektrometrilla, optisella emissiospektrometrilla, lämpösekä painemittareilla. Laskennan ja kokeiden pohjalta selvitettiin optimaalinen seossuhde plasmakaasulle, paineen ja tehon noston vaikutus hartsin polttonopeuteen sekä jatkuvatoimisen syöttömenetelmän edut panostoimiseen syöttöön. Rfgeneraattorin teho rajoitti jatkuvatoimisen polttonopeuden 130 g/h ja hetkellisen polttonopeuden 175 g/h. Radioaktiivisten aineiden pidätys oli 93,5 % cesiumin osalta. Tulosten perusteella 4 kg/h ioninvaihtohartsia polttavan laitteiston tehon lähteeksi tarvitaan 65 kW rfgeneraattori. Palamattoman hartsin ja tuhkan kulkeutuminen partikkelisuodattimille sekä reaktiotuotteena syntyvien rikinoksidien käsittely vaatii vielä jatkotutkimusta.