O Ruído de Baixa Frequência (LFN), tais como o ruído flicker e o Random Telegraph Noise (RTN), são limitadores de performance em muitos circuitos analógicos e digitais. Para transistores diminutos, a densidade espectral de potência do ruído pode variar muitas ordens de grandeza, impondo uma séria limitação na performance do circuito e também em sua confiabilidade. Nesta tese, nós propomos um novo modelo de RTN estatístico para descrever o ruído de baixa frequência em MOSFETs. Utilizando o modelo proposto, pode-se explicar e calcular o valor esperado e a variabilidade do ruído em função das polarizações, geometrias e dos parâmetros físicos do transistor. O modelo é validado através de inúmeros resultados experimentais para dispositivos com canais tipo n e p, e para diferentes tecnologias CMOS. É demonstrado que a estatística do ruído LFN dos dispositivos de canal tipo n e p podem ser descritos através do mesmo mecanismo. Através dos nossos resultados e do nosso modelo, nós mostramos que a densidade de armadilhas dos transistores de canal tipo p é fortemente dependente do nível de Fermi, enquanto para o transistor de tipo n a densidade de armadilhas pode ser considerada constante na energia. Também é mostrado e explicado, através do nosso modelo, o impacto do implante de halo nas estatísticas do ruído. Utilizando o modelo demonstra-se porque a variabilidade, denotado por σ[log(SId)], do RTN/LFN não segue uma dependência 1/√área; e fica demonstrado que o ruído, e sua variabilidade, encontrado em nossas medidas pode ser modelado utilizando parâmetros físicos. Além disso, o modelo proposto pode ser utilizado para calcular o percentil do ruído, o qual pode ser utilizado para prever ou alcançar certo rendimento do circuito. / Low Frequency Noise (LFN) and Random Telegraph Noise (RTN) are performance limiters in many analog and digital circuits. For small area devices, the noise power spectral density can easily vary by many orders of magnitude, imposing serious threat on circuit performance and possibly reliability. In this thesis, we propose a new RTN model to describe the statistics of the low frequency noise in MOSFETs. Using the proposed model, we can explain and calculate the Expected value and Variability of the noise as function of devices’ biases, geometry and physical parameters. The model is validated through numerous experimental results for n-channel and p-channel devices from different CMOS technology nodes. We show that the LFN statistics of n-channel and p-channel MOSFETs can be described by the same mechanism. From our results and model, we show that the trap density of the p-channel device is a strongly varying function of the Fermi level, whereas for the n-channel the trap density can be considered constant. We also show and explain, using the proposed model, the impact of the halo-implanted regions on the statistics of the noise. Using this model, we clarify why the variability, denoted by σ[log(SId)], of RTN/LFN doesn't follow a 1/√area dependence; and we demonstrate that the noise, and its variability, found in our measurements can be modeled using reasonable physical quantities. Moreover, the proposed model can be used to calculate the percentile quantity of the noise, which can be used to predict or to achieve certain circuit yield.

A teoria da perturbação baseada em múltiplas escalas temporais é usada neste trabalho para estudar as interações não lineares entre ondas na atmosfera no contexto das equações primitivas no plano beta-equatorial em coordenadas isobáricas. As ondas equatoriais de Rossby, mista Rossby-gravidade, gravidade-inerciais e Kelvin, com diferentes estruturas verticais, são obtidas como soluções de ordem dominante. A partir da condição de solvabilidade do problema de ordem superior, foi obtido um modelo assintótico reduzido que governa a interação fracamente não linear entre as ondas numa determinada tríade ressonante. A conservação da energia total para a solução de ordem dominante do modelo de equações original implica que a soma dos coeficientes de interação numa tríade ressonante qualquer deve ser nula. Usando um método gráfico, foram encontradas algumas tríades ressonantes envolvendo ondas baroclínicas equatorialmente confinadas e ondas de Rossby barotrópicas possuindo significativa influência em médias e altas latitudes. Duas tríades ressonantes receberam especial atenção devido ao significativo acoplamento entre os modos e à possível relação desses modos com alguns aspectos observados acerca dos fenômenos de baixa freqüência na atmosfera. A primeira tríade é composta por uma onda de Rossby barotrópica possuindo o segundo modo meridional interagindo ressonantemente com uma onda mista de Rossby-gravidade com a estrutura vertical do primeiro modo baroclínico, ambas possuindo o mesmo número de onda zonal, por meio de um modo geostrófico zonalmente simétrico (k = 0) possuindo a mesma estrutura vertical da onda mista e o modo meridional n = 1. A segunda tríade é constituída por uma onda mista de Rossby-gravidade com número de onda-2, uma onda de Kelvin com número de onda-1, ambas associadas ao primeiro modo baroclínico, e uma onda de Rossby barotrópica com número de onda-3 e modo meridional n = 2. A integração das equações reduzidas para essas duas tríades ressonantes mostra que para as amplitudes iniciais dos modos caracterizando magnitudes típicas de anomalias atmosféricas observadas, os modos na primeira tríade, em geral, trocam energia na escala intra-sazonal, enquanto os modos na segunda tríade trocam energia na escala intra-sazonal ou numa escala semi-anual, dependendo da amplitude inicial do modo de Rossby barotrópico. São discutidas as implicações dos resultados para a dinâmica da interação trópicos-extratrópicos na escala de baixa-freqüência do espectro dos movimentos atmosféricos. / The asymptotic perturbation theory based on multiple scales in time is used to investigate the nonlinear interactions among equatorial waves in an equatorial beta-plane adiabatic primitive equation atmospheric model in isobaric coordinates. The equatorial Rossby, mixed Rossby-gravity, Kelvin and inertio-gravity waves, with several vertical structures, are obtained as the leading-order solution. From the solvability condition of the problem, a reduced model governing the weakly nonlinear interaction of the waves in a particular resonant triad was obtained. The total energy conservation of the leading-order solution of the original model equations implies that the sum of the coupling coefficients in any resonant triad must be zero. Using a graphical approach, we determined some resonant triads involving equatorially trapped baroclinic waves and barotropic Rossby waves having large mid-latitude amplitude. Two particular interactions deserve special attention because of their strong coupling and their possible relation to observed features in the atmospheric circulation. One is characterized by a first baroclinic mode structure mixed Rossby-gravity wave interacting with a barotropic Rossby wave with the second gravest meridional mode, both having the same wavenumber, through a zonally symmetric geostrophic mode with the same vertical structure as the Yanai wave and having the n = 1 meridional mode. The other triad is composed of a zonal wavenumber-1 Kelvin wave, a zonal wavenumber-2 mixed Rossby-gravity wave, both with the first baroclinic mode vertical structure, and a barotropic zonal wavenumber-3 Rossby wave having the second gravest meridional mode. The barotropic Rossby waves in these two triad interactions have significant projection onto middle and higher latitudes. The integration of the triad equations for these particular interactions shows that, for the initial mode amplitudes characterizing typical magnitudes of atmospheric flow perturbations, the modes in the first triad usually exchange energy on intraseasonal time-scales, while the modes in the second triad exchange energy on either intraseasonal or semi-annual time-scale, depending on the initial condition. The implications of the results for the dynamics of tropics-extratropics interaction on low-frequency time-scales are discussed.

Abstract Brain activity fluctuations occur in multiple spatial and temporal scales. Functional magnetic resonance imaging (fMRI) has shown that infra slow fluctuations (ISF) of blood oxygen level-dependent signal (BOLD) are organized into well-defined areas called resting state networks (RSN). ISFs have also been detected in full-band EEG (fbEEG) data and in recent years, many have combined these two modalities to enable more accurate measurements of brain fluctuations. In simultaneous EEG-fMRI measurements the ISFs of BOLD signal have been found to be correlated with amplitude envelopes of faster electrophysiological data, suggesting the same underlying neuronal dynamics. Also direct correlations have been found in task related studies but not previously in resting state studies. Understanding the relation between EEG and BOLD signal in resting state might prove beneficial in the research of baseline activity fluctuations of the brain. Functional connectivity (FC) of the RSNs has been found to vary in different tasks and in some diseases, but also in resting state in healthy people. Despite numerous studies, no clear cause for these variations has yet been found. To research these open questions we performed simultaneous fbEEG-fMRI studies. The measurements from both modalities were analyzed with independent component analysis to improve the comparability of these results. Correlation analysis revealed that the EEG ISFs correlate with BOLD signal both temporally and spatially. These correlations showed spatiotemporal variability that was related to the strength of RSN functional connectivity. These results indicate that the ISFs of EEG and BOLD reflect a common source of fluctuations. The understanding of the correlations between ISFs in EEG and fMRI BOLD signals gives basic information of brain dynamics and of the variables that affect it. A better understanding of the background of brain activity helps in the development of more effective treatments for various neurological diseases as the knowledge of the mechanisms behind them grows. The ability to measure RSN activity with EEG more accurately can help in the development of new methods for early diagnosis of diseases. / Tiivistelmä Aivojen toiminta vaihtelee monissa avaruudellisissa ja ajallisissa mittakaavoissa. Toiminnallisissa magneettikuvauksissa (TMK) on havaittu, että veren happipitoisuudesta riippuvan (engl. BOLD) signaalin erittäin hitaat vaihtelut ovat järjestäytyneet hyvin määriteltyihin alueisiin, joita kutsutaan lepotilahermoverkostoiksi. Erittäin hitaita vaihteluita on havaittu myös täysikaistaisesta aivosähkökäyrästä (fbEEG). Viime vuosina nämä kaksi menetelmää on usein yhdistetty tarkemman mittaustuloksen aikaansaamiseksi. Samanaikaisissa EEG-TMK-mittauksissa BOLD signaalin erittäin hitaiden vaihteluiden on huomattu korreloivan nopeampien elektrofysiologisten värähtelyjen amplitudien verhokäyrien kanssa, mikä viittaa samaan perustana olevaan neuraaliseen dynamiikkaan. Myös suoria korrelaatioita on löydetty tehtäviin liittyvissä tutkimuksissa, mutta ei aiemmin lepotilatutkimuksissa. Lepotilan EEG:n ja BOLD-signaalin suhteen ymmärrys voi osoittautua hyödylliseksi aivojen perustilan aktiivisuuden vaihteluiden tutkimisessa. Hermoverkostojen toiminnallisen liittyvyyden on todettu huojuvan tietyissä tehtävissä ja joissain sairauksissa, mutta myös lepotilassa terveillä henkilöillä. Runsaasta tutkimuksesta huolimatta ei liittyvyyden huojunnalle ole vielä löytynyt selkeää aiheuttajaa. Näiden avoimien kysymysten tutkimiseksi suoritimme yhdenaikaisia fbEEG-TMK-mittauksia. Kummankin modaliteetin mittaustuloksia analysoitiin itsenäisten komponenttien analyysillä tulosten vertailtavuuden parantamiseksi. Korrelaatioanalyysit osoittivat, että EEG:n erittäin hitaat vaihtelut korreloivat ajallisesti ja avaruudellisesti TMK:n BOLD-signaalin kanssa. Näissä korrelaatioissa esiintyi sekä paikkaan että aikaan liittyvää huojuntaa, joka oli yhteydessä lepotilahermoverkostojen toiminnallisen liittyvyyden vahvuuteen. Nämä tulokset viittaavat siihen, että samat tekijät tuottavat EEG:n ja TMK:n BOLD-signaalien hitaat vaihtelut. EEG:n ja TMK:n signaalien erittäin hitaiden vaihteluiden välisen korrelaation ymmärtäminen antaa perustason tietoa aivojen toiminnan dynamiikasta sekä siihen vaikuttavista tekijöistä. Parempi ymmärrys aivotoiminnan taustoista auttaa kehittämään tehokkaampia hoitoja neurologisiin sairauksiin, kun tieto mekanismeista niiden takana tarkentuu. Mahdollisuus mitata lepotilahermoverkostojen toimintaa EEG:llä aiempaa tarkemmin voi auttaa kehittämään uusia menetelmiä sairauksien varhaiseen diagnostiikkaan.

Deux approches potentiellement anti-tumorales, employant des nanoparticules magnétiques (NPMs) et des champs magnétiques oscillants, furent étudiées. La première, l’hyperthermie magnétique, utilise l’échauffement de NPMs au contact des cellules tumorales provoqué par un champ magnétique alternatif haute-fréquence. Durant cette thèse, il fut démontré que les forces magnéto-mécaniques induites par les inhomogénéités de champ magnétique pendant un essai d’hyperthermie magnétique n’avaient aucune influence sur la viabilité cellulaire. Egalement, des mesures magnétiques, d’XPS, et de puissance de chauffe de NPMs de fer enrobées d’une coquille de silice amorphe furent effectuées et analysées. Il fut observé que cette coquille permettait de préserver les propriétés magnétiques des NPMs suite à l’exposition à un environnement aqueux. La deuxième approche anti-tumorale utilise des NPMs soumises à un champ magnétique basse-fréquence, induisant une stimulation mécanique des cellules tumorales. Une étude théorique complète de l’influence du champ magnétique, de l’agitation thermique et des interactions magnétiques sur la force magnéto-mécanique exercée par des NPMs, fut effectuée. Elle démontra notamment que cette force augmente de manière drastique pour une assemblée de NPMs lorsque la rotation du champ magnétique induit une rupture de symétrie dans l’évolution temporelle du couple magnéto-mécanique. Expérimentalement, il fut développé différents prototypes de génération de champ magnétique tournant à basse fréquence. Des tests in vitro furent réalisés en utilisant des NPMs enrobées par une matrice de phosphatidylcholine, leur permettant d’être solidaires des membranes cellulaires. Suite à la rotation d’un champ magnétique de 40 ou 380 mT, à 10 Hz, il fut observé une réduction de la survie cellulaire. / Two anti-tumor treatments based on magnetic nanoparticles (MNPs) and oscillating magnetic field were studied. The first one, magnetic hyperthermia, uses the heat released by MNPs in contact with tumor cells under a high frequency alternating magnetic field. We have shown that the forces induced by magnetic field inhomogeneity during magnetic hyperthermia essay no influence on cellular viability. Moreover, magnetic measurements, XPS characterization and heating power evaluation of iron MNPs coated by amorphous silica shell were carried out. It was observed that this shell is able to preserve the MNP magnetic properties submitted to an aqueous environment. The second anti-tumor treatment combines MNPs and low-frequency magnetic field, inducing mechanical stress to tumor cells. A complete theoretical study on the influence of magnetic field, thermal agitation and magnetic interaction on the magneto-mechanical forces generated by the MNPs was carried out. It was demonstrated that for a MNP assembly this force increases dramatically when the rotation of the magnetic field induces a break of time reversal symmetry on the magneto-mechanical torque. Experimentally, several devices generating low frequency rotating magnetic fields were developed. Using these devices, in-vitro essays were also achieved using phosphatidylcholine coated MNPs, which bind to cellular membranes. An application of a 40 or 380 mT magnetic field rotating at 10 Hz reduced cell survival rate.

Abstract A cardiorespiratory system is highly regulated via the autonomic nervous system (ANS), whose function can be quantified noninvasively by analyzing electrocardiogram (ECG), blood pressure (BP) and respiration signals. Several conditions and illnesses are linked with imbalance of the ANS. This thesis aimed to develop methods for describing the ANS regulation of a cardiovascular system from short-term cardiorespiratory measurements. More specifically, the role of breathing rate and its effects on traditional frequency domain based cardiovascular indexes describing ANS control is addressed. The main contributions are as follows: 1) an adaptive filtering based method to remove respiratory influences from cardiovascular signals and indexes was developed. The adaptive filter reduced the bias caused by low respiration rate, enabling the usage of spontaneous respiration measurement protocol over controlled respiration. 2) Methods to quantify respiratory sinus arrhythmia (RSA) index from cardiovascular signals were developed as well: two methods utilizes adaptive filtering and either the measured respiration signal or the ECG-derived respiration signal and one method uses independent component analysis. Developed RSA index methods allow varying respiration rates making them physiologically more accurate than traditional high frequency power with fixed respiration rate, often used as RSA index. 3) Tools for studying the power and the frequency of low frequency (LF) oscillations of cardiovascular signals were developed, including a time-frequency representation for analyzing varying data. An experimental study was conducted with patients of continuum of cardiovascular risks. According to results, aging decreased the frequency of LF oscillation, whereas coronary artery disease decreased it further. 4) Two new ECG-derived respiration (EDR) methods utilizing decomposition techniques were developed. The proposed methods yielded statistically significant improvements over previously developed EDR methods. EDR method enables to get respiratory information from ECG, which in its turn reduces needed modalities in ANS quantification. This thesis provides methods to quantify indexes describing the ANS function more accurately by acknowledging the respiration effects. The results of this thesis may be utilized in various application areas, ranging from clinical to physiology research up to commercial health, wellness and sport products. / Tiivistelmä Autonominen hermosto säätelee tarkasti sydän- ja verenkiertoelimistöä sekä hengitystä. Autonomisen hermoston toimintaa voidaan analysoida laskennallisin menetelmin noninvasiivisesti mitatuista elektrokardiogrammi- (EKG, sydänsähkökäyrä), verenpaine- ja hengityssignaaleista. Useita tekijöitä ja sairauksia voidaan yhdistää autonomisen hermoston epätasapainoon. Väitöskirjassa kehitettiin menetelmiä sydän- ja verisuonijärjestelmän autonomisen säätelyn kuvaamiseksi lyhytaikaisista kardiorespiratorisista tallenteista. Erityistä huomiota on kiinnitetty hengityksen vaikutukseen perinteisiin taajuustasosta laskettaviin muuttujiin, jotka kuvaavat autonomisen hermoston toimintaa. Väitöskirjan päätuloksia ja -tuotoksia ovat: 1) uusi adaptiiviseen suodatukseen pohjautuva laskennallinen menetelmä hengitysvaikutuksien poistamiseksi sydän- ja verisuonisignaaleista. Adaptiivinen suodatin vähensi matalan hengitystaajuuden aiheuttamaa vääristymää hermoston toimintaa kuvaavista parametreistä. Uusi menetelmä mahdollistaa kontrolloimattoman eli vapaan hengitystaajuus-protokollan käytön autonomisen hermoston toiminnan mittauksissa. 2) Uusia menetelmiä respiratorisen sinus arrytmian (RSA) määrittämiseksi sydän- ja verisuonisignaaleista. Kehitetyissä menetelmistä kahdessa käytetään adaptiivista suodatusta hyödyntäen joko mitattua hengityssignaalia tai EKG:stä johdettua hengityssignaalia. Kolmas menetelmä pohjautuu itsenäisten komponenttien analyysiin. Kehitetyt menetelmät RSA:n laskemiseksi sallivat hengitystaajuuden vaihtelun mittauksien aikana, mikä tekee ne fysiologisesti tarkemmaksi kuin perinteisesti käytetty korkeataajuinen (HF) komponentti, joka lasketaan taajuustasossa tietyltä kaistalta riippumatta hengitystaajuudesta. 3) Kehitettiin ja sovellettiin menetelmiä EKG:n ja verenpaineen matalataajuisten (LF) heilahtelujen tutkimista varten. Yhdessä tutkimuksessa sovellettiin aika-taajuustason esitystapaa vaihtelevan datan analysoimiksi. Kokeellinen tutkimus tehtiin aineistolla, joka oli jatkumo sydän- ja verisuonitautien riskejä omaavista potilaista jo sairastuneisiin potilaisiin. Ikääntyminen pienensi matalataajuisen heilahtelun taajuutta ja sepelvaltimosairaus pienensi sitä edelleen. 4) Kaksi uutta hajotelmatekniikoita hyödyntävää menetelmää, joilla lasketaan EKG:stä hengitysvirtausignaali-estimaatti (EDR). Kehitettyjen EDR-menetelmien suorituskyky osoittautui tilastollisesti paremmaksi kuin aikaisemmat menetelmät. Koska hengityssignaali ja -taajuus voidaan johtaa suoraan EKG:stä, tarvittavien mittaussensoreiden määrää vähenee. Lisäksi EDR:ää voidaan hyödyttää autonomisen hermoston toimintaa kuvaavien parametrien estimoinnissa. Väitöskirja tarjoaa menetelmiä autonomisen hermoston toiminnan mittaamiseksi huomioiden erityisesti hengityksen vaikutus estimoitaviin parametreihin. Väitöskirjan tuloksia voidaan soveltaa useissa kardiorespiratorisia signaaleja hyödyntävissä sovelluksissa aina kliinisestä työstä fysiologian tutkimukseen ja kaupallisiin hyvinvointi-, terveys- ja urheilusovelluksiin. / Huomautus/Notice Painetussa virheellinen ISBN: 978-952-62-2312-4, oikea 978-952-62-2310-0. Printed version has incorrect ISBN: 978-952-62-2312-4, it should be 978-952-62-2310-0.

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This master’s thesis is dealing with low frequency all valve stereo amplifier unit conception for an electric guitar. The amplifier contains two independent output stages with two power tubes EL34, working in AB class, with 40Watts of power. The apparatus is equipped with two channels, EQ correctors, parallel effects loop, output selection with lowered anode power supply, selection between silicon or tube rectifier. The preamplifier works in mono mode and the stereophony is reached by dividing the signal in an added effects system. This unusual solution differs from both monaural conceptions and binaural power amplifiers which contains no preamp. It offers the possibility of stereophony without the necessity of dividing the guitar signal before the amplifier’s input. The sound that comes from the speaker on one side is effected and on the other side is dry by using monaural effects apparatus. The sound from both speakers is effected by using binaural effect apparatus. The amplifier can be used as power amplifier stage only when the return of the effect loop is used as the amplifier input. Every available possible solution is discussed in case of each block and then the most suitable is chosen. The biggest attention is paid to a proposal and calculation of both power and output transformer, ergonomical lay-out of the stages in need of the best S/N separation. The stages were simulated in Micro-Cap 9.0 and Tonestack 1.3 computer programmes. The construction was carried out with the emphasis on proper shielding and grounding. The overall stability tests were performed after building the amplifier as well as frequency characteristics with the scope and distortion with the distortion meter.

v anglickém jazyce The possible assessments of unprofessional exposures of low frequency noise Introduction: Along with technical development, the number of sources of low frequency noise increases in the human environment and the number of complaints from people exposed to noise from these sources increases as well. The statutory limit for non-professional exposure to low frequency noise has not yet been established (due to the limited amount of data on low frequency noise exposure risks) in the EU countries (USA) and no WHO recommendations have been issued in this area. For these reasons, the hygienic limit for municipal/non-professional exposure to low frequency noise was not specified in the Czech Republic. Objecticve: The present dissertation thesis was to investigate whether the short-term experimental exposure to low frequency noise with the tonic component induces significant changes in the circadian rhythm of cortisol and alpha-amylase in saliva in the experimental set of volunteers. Saliva is a biological material that allows low-invasiveness collection. The work was supposed to assess whether possible changes could be used as objective indicators of the presence of the stress response to the noise exposure. Material and metods: An experimental study was conducted on a set of 100...

In order to understand how the brain functions, under normal as well as pathological conditions, it is important to study the mechanisms underlying information integration. Depending on the nature of an input arriving at a synapse, different strategies may be used by the neuron to integrate and respond to the input. Naturally, if a short train of high-frequency synaptic input arrives, it may be beneficial for the neuron to be equipped with a fast mechanism that is highly sensitive to inputs on a short time scale. If, on the contrary, inputs arriving with low frequency are to be processed, it may be necessary for the neuron to possess slow mechanisms of integration. For example, in certain working memory tasks (e. g. delay-match-to-sample), sensory inputs may arrive separated by silent intervals in the range of seconds, and the subject should respond if the current input is identical to the preceeding input. It has been suggested that single neurons, due to intrinsic mechanisms outlasting the duration of input, may be able to perform such calculations. In this work, I have studied a mechanism thought to be particularly important in supporting the integration of low-frequency synaptic inputs. It is mediated by a cascade of events that starts with activation of group I metabotropic glutamate receptors (mGlu1/5), and ends with a membrane depolarization caused by a current that is mediated by canonical transient receptor potential (TRPC) ion channels. This current, denoted ITRPC, is the focus of this thesis. A specific objective of this thesis is to study the role of ITRPC in the integration of synaptic inputs arriving at a low frequency, < 10 Hz. Our hypothesis is that, in contrast to the well-studied, rapidly decaying AMPA and NMDA currents, ITRPC is well-suited for supporting temporal summation of such synaptic input. The reason for choosing this range of frequencies is that neurons often communicate with signals (spikes) around 8 Hz, as shown by single-unit recordings in behaving animals. This is true for several regions of the brain, including the entorhinal cortex (EC) which is known to play a key role in producing working memory function and enabling long-term memory formation in the hippocampus. Although there is strong evidence suggesting that ITRPC is important for neuronal communication, I have not encountered a systematic study of how this current contributes to synaptic integration. Since it is difficult to directly measure the electrical activity in dendritic branches using experimental techniques, I use computational modeling for this purpose. I implemented the components necessary for studying ITRPC, including a detailed model of extrasynaptic glutamate concentration, mGlu1/5 dynamics and the TRPC channel itself. I tuned the model to replicate electrophysiological in vitro data from pyramidal neurons of the rodent EC, provided by our experimental collaborator. Since we were interested in the role of ITRPC in temporal summation, a specific aim was to study how its decay time constant (τdecay) is affected by synaptic stimulus parameters. The hypothesis described above is supported by our simulation results, as we show that synaptic inputs arriving at frequencies as low as 3 - 4 Hz can be effectively summed. We also show that τdecay increases with increasing stimulus duration and frequency, and that it is linearly dependent on the maximal glutamate concentration. Under some circumstances it was problematic to directly measure τdecay, and we then used a pair-pulse paradigm to get an indirect estimate of τdecay. I am not aware of any computational model work taking into account the synaptically evoked ITRPC current, prior to the current study, and believe that it is the first of its kind. We suggest that ITRPC is important for slow synaptic integration, not only in the EC, but in several cortical and subcortical regions that contain mGlu1/5 and TRPC subunits, such as the prefrontal cortex. I will argue that this is further supported by studies using pharmacological blockers as well as studies on genetically modified animals. / QC 20101005

The financial sector stands for an important part of society’s fundamental infrastructure andnational economy. Previous financial crises indicate the importance of having a well-regulatedfinancial market. Former directives of regulating the insurance industry had insufficient solvencyregulations and were lacking in risk management. Therefore, the regulatory framework SolvencyII, the successor to Solvency I, has been established on the European market. The objective ofSolvency II is to ensure consumer protection by ensuring insurance companies properly reflectthe risks their businesses are vulnerable to.The regulatory framework Solvency II came into force in the turn of 2015/2016. However, it hasbeen on every insurers’ agenda for years and preparations have been done. It is therefore ofinterest to investigate how Swedish insurance companies have adjusted to Solvency II at an earlystage after the transition.This has been investigated by conducting interviews with mainly Chief Risk Officers and RiskManagers at Swedish insurance companies. As a complement, a questionnaire was distributed toasset and capital managers, having insurers as customers, regarding their perception of insurers’changes in investment behaviors.The findings of this study imply that insurance companies have had a compliance focus to adoptthe regulation rather than a business focus. No indications of adjustments to corporate businessstrategy has yet been noticed. However, some companies have developed a risk culture withinthe organizations. The extensive reporting and calculations of capital that Solvency II entails, haslead to implementations of new systems and processes for companies. It is further noticed thatSwedish insurance companies use the standard model for calculating the capital requirements.Solvency II has lead to increased understanding of the trade-off between capital, risk, and returnby holding a risk-adjusted capital. Also, an increased engagement of employees in the riskmanagement process has been noticed. The companies are aligned with the ORSA process, sinceit is one of the requirements, and are aware of the potential benefits the ORSA process cancontribute to. Lastly, this study indicates an improved risk awareness and culture within theinsurance companies by educating existing employees and employing new competentemployees.