Growing request for wideband communications requires innovation in power efficiency and signal processing. Without the use of any peak to average power ratio (PAPR) reduction technique, the efficiency of power consumption at the transmitter end becomes very poor. PAPR reduction in this work is accomplished based on using a unique class of functions, prolate spheroidal wave functions (PSWFs). The difficulty arises from the fact that these pulses do not belong to the Nyquist family. A zero forcing equalizer (ZFE) is designed to compensate intersymbol interference (ISI), and its performance is studied under the presence of AWGN. Considering PAPR and ISI as the constraints of communication systems, based on the properties of PSWF, a set of pulses with minimum ISI with respect to a specific amount of PAPR is achieved by defining an optimization problem. The desired level of PAPR is considered to be moved to the constraint set to convert the multi-objective problem into a single objective problem. The results of the numerical optimization of both ISI and PAPR are presented along with a couple of examples of comparison between the resultant pulse and the conventional square root raised cosine. It is shown that by achieving the same level of PAPR of the SRRC, the obtained pulse is a close approximation of SRRC. An implementation based on state variable filters is introduced to realize PSWF for high speed applications. An example based on this approach is presented to compare the finite pole approximation result with the original pulse.

Ultra-Wideband (UWB) is an emerging wireless technology that has attracted many applications in modern day communications. Its ability to provide high data rates at very low complexity makes the system attractive for many indoor high-speed wireless communications. UWB signal can be transmitted by either impulse radio (IR) or multicarrier techniques. Impulse radio technique in particular, is a carrier less technology using pulses in the range of nanoseconds or less providing a low complexity, low power and low interference susceptible wireless system. These features motivate the usage of energy detection based receiver structures that operates at very low power. With the recent developments in UWB technology, a promising feature of this system is to provide high data rate with transceivers operating at very low power. High data rate on the other hand can be achieved only by using a complex modulation schemes that requires more transmitted power. As a limitation in the spectral emission associated with UWB, only low-level modulation technology can be used in UWB systems. Hence, in order to achieve high data rates using low-level modulation schemes, the Inter-symbol interference (ISI) becomes unavoidable. Decision feedback equalization (DFE) is one of the signal process techniques that can be used to mitigate the effects of ISI. This thesis proposes an energy subtraction algorithm combining with the principles of DFE to mitigate the effects of ISI in an impulse radio UWB system employing energy detection receiver. Computer simulations have been performed to verify the operation of the new proposed algorithm under UWB channel characteristics and relevant comparisons have been made with the basic energy detection receiver. Simulation results show that the ISI can be effectively mitigated with low system complexity.

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<p>Cilj: Brzina ispaljivanja neuralnih impulsa u kori velikog mozga je veoma promenljiva &scaron;to ukazuje da bi Poasonov tačkasti proces mogao da bude pogodan za modelirqnje takvog procesa. Međutim, brojna istraživanja su pokazala da statistika ispaljivanja ne sledi Poasona. Uprkos tome, jo&scaron; uvek se nije iskristalisao ni alternativni mehanizam koji bi opisao generisanje spajkova, ni raspodela koja bi opisala raspodelu intervala između spajkova (ISI). Ključni cilj ove disertacije je statistička analiza koja će omogućiti modelovanje ISI vremenskih nizova snimljenih u različitim delovima kore velikog mozga dok su majmuni re&scaron;avali različite probleme.<br />Metoda: Primenjena je robusna neparametarska statistika da bi se odredila funkcija gustine raspodele (PDF) ISI vremenskih nizova. Rezultati su verifikovani butstrep metodom i iskori&scaron;ćeni za kreiranje Markovljevog modela.<br />Rezultati: Pokazalo se da se raspodela ISI intervala ne može opisati samo jednom funkcijom i da se statistika ne može da poveže isključivo sa već postojećim modelima, uključujući i eksponencijalni. Pokazalo se, zatim, da ISI statistika ne zavisi od regije u kori velikog mozga, niti, unutar jedne regije, od problema koji je budni majmun re&scaron;avao. Međutim, ISI mizovi snimani dok je majmun re&scaron;avao isti problem ali u različitim vremenskim intervalima nisu statistički slični, &scaron;to ukazuje na postojanje varijabiliteta u ISI vremenskim nizovima u zavisnosti od problema koji se re&scaron;ava.<br />Zaključak: Rezultati analize signala ukazuju da je neuralna aktivnost posledica komplesnih generi&scaron;ućih mehanizama sa značajnom međuzavisno&scaron;ću i da process zavisi od zadatka koji se re&scaron;ava.</p> / <p>Objectives: High variability of neuronal firing patterns in the cerebral cortex points towards spiking activity models based on Poisson point processes. In spite of growing evidence that firing behavior may fail Poisson statistics, an alternate spike generating mechanisms and the resulting inter-spike interval (ISI) distributions have not been clarified yet. The key objective of this thesis is to perform a statistical analysis that would yield a model of ISI time series recorded from different from different cortical areas of awake monkeys performing various behavioral tasks.<br />Methods: A robust and non-parametrical statistics to determine ISI probability density functions (PDF-s) of extracellularly recorded cerebral cortical neurons of behaving macaque monkeys is performed. The results were validated using the bootstrap method. The obtained statistics were used to create a Markov model of ISI time series.<br />Results: It turned out that there is no single ISI distribution, but many, and that the underlying statistics is not associated exclusively to the current established models including the exponential. Distribution of types of ISI statistics obtained from different cortical areas are statistically similar and the same applies to the statistics obtained from the same cortical area by ignoring ongoing behavior. However, particular ISI time series observed during the time epochs of the same behavioral task did not show statistical similarity, suggesting a task dependent variation of spike generating dynamics.<br />Conclusion: In summary, the results indicate that neuronal firing activity is resulted by complex generative mechanisms with significant dependency and that this process is contingent upon the behavior.</p>

Recent advancements in iterative processing have allowed communication systems to perform close to capacity limits withmanageable complexity.For manychannels such as the AWGN and flat fading channels, codes that perform only a fraction of a dB from the capacity have been designed in the literature. In this dissertation, we will focus on the design and analysis of near-capacity achieving codes for another important class of channels, namely inter-symbol interference (ISI)channels. We propose various coding schemes such as low-density parity-check (LDPC) codes, parallel and serial concatenations for ISI channels when there is no spectral shaping used at the transmitter. The design and analysis techniques use the idea of extrinsic information transfer (EXIT) function matching and provide insights into the performance of different codes and receiver structures. We then present a coding scheme which is the concatenation of an LDPC code with a spectral shaping block code designed to be matched to the channel??s spectrum. We will discuss how to design the shaping code and the outer LDPC code. We will show that spectral shaping matched codes can be used for the parallel concatenation to achieve near capacity performance. We will also discuss the capacity of multiple antenna ISI channels. We study the effects of transmitter and receiver diversities and noisy channel state information on channel capacity.

We present a serially concatenated coding scheme for partial response channels. The encoder consists of an outer irregular LDPC code and an inner matched spectrum trellis code. These codes are shown to offer considerable improvement over the i.i.d. capacity (> 1 dB) of the channel for low rates (approximately 0.1 bits per channel use). We also present a qualitative argument on the optimality of these codes for low rates. We also formulate a performance index for such codes to predict their performance for low rates. The results have been verified via simulations for the (1-D)/sqrt(2) and the (1-D+0.8D^2)/sqrt(2.64) channels. The structure of the encoding/decoding scheme is considerably simpler than the existing scheme to maximize the information rate of encoders over partial response channels.

We present a serially concatenated coding scheme for partial response channels. The encoder consists of an outer irregular LDPC code and an inner matched spectrum trellis code. These codes are shown to offer considerable improvement over the i.i.d. capacity (> 1 dB) of the channel for low rates (approximately 0.1 bits per channel use). We also present a qualitative argument on the optimality of these codes for low rates. We also formulate a performance index for such codes to predict their performance for low rates. The results have been verified via simulations for the (1-D)/sqrt(2) and the (1-D+0.8D^2)/sqrt(2.64) channels. The structure of the encoding/decoding scheme is considerably simpler than the existing scheme to maximize the information rate of encoders over partial response channels.

Recent advancements in iterative processing have allowed communication systems to perform close to capacity limits withmanageable complexity.For manychannels such as the AWGN and &#64258;at fading channels, codes that perform only a fraction of a dB from the capacity have been designed in the literature. In this dissertation, we will focus on the design and analysis of near-capacity achieving codes for another important class of channels, namely inter-symbol interference (ISI)channels. We propose various coding schemes such as low-density parity-check (LDPC) codes, parallel and serial concatenations for ISI channels when there is no spectral shaping used at the transmitter. The design and analysis techniques use the idea of extrinsic information transfer (EXIT) function matching and provide insights into the performance of di&#64256;erent codes and receiver structures. We then present a coding scheme which is the concatenation of an LDPC code with a spectral shaping block code designed to be matched to the channel??s spectrum. We will discuss how to design the shaping code and the outer LDPC code. We will show that spectral shaping matched codes can be used for the parallel concatenation to achieve near capacity performance. We will also discuss the capacity of multiple antenna ISI channels. We study the effects of transmitter and receiver diversities and noisy channel state information on channel capacity.

Des systèmes injectables de formation in situ ont été utilisés dans les dernières années pour l'obtention de formulations de préparation facile et permettant la libération prolongée de principes actifs. Ces systèmes utilisant des solvants biocompatibles et des polymères biodégradables sont des liquides (solutions ou émulsions) qui une fois injectés dans l'organisme donnent lieu à des implants (ISI) ou à des microparticules (ISM) solides. La formation de ces systèmes est induite par la précipitation du polymère à partir des solutions polymériques qu'ils contiennent lors du contact avec les fluides corporaux aqueux. Dans ce travail, des ISI et des ISM, réalisés à partir des polymères de l'acide lactique et/ou glycolique (PLA et PLGA) et des différents solvants biocompatibles, pour la libération prolongée d?ivermectine (IVM), un principe actif antiparasitaire faiblement biodisponible par la voie orale, ont été développés. Les profils de libération du principe actif in vitro et in vivo à partir de ces systèmes, ont été comparés avec ceux obtenus à partir de microparticules réalisées par la méthode classique dite d'émulsion simple - évaporation de solvant ; il s'agit d'une technique aux multiples étapes, à coût élevé et dont l'utilisation de solvants toxiques la font difficilement industrialisable. La libération du principe actif à partir des microparticules obtenues par émulsion simple/évaporation du solvant a été influencée par la forte interaction du principe actif avec les polymères mais aussi par la porosité. Dans le cas des systèmes in situ, la vitesse de libération d'IVM a été conditionnée par la solubilité dans l'eau du solvant biocompatible sélectionné et par les interactions solvant/polymère. Pour les ISM, des paramètres tels que la nature de la phase externe, aqueuse (ISM-O/W) ou huileuse (ISM-O/O), la solubilité dans l'eau du solvant de la phase interne, l'affinité entre les phases et l'affinité de l'IVM pour chacune des phases, ont déterminé la vitesse de libération du principe actif. La bonne stabilité ainsi que les profils de libération plus prolongés et présentant une faible libération initiale du principe actif in vivo et in vitro, ont montré que les ISI et les ISM réalisés à partir de solvants biocompatibles de faible solubilité dans l'eau tels que la triacetine sont les plus indiqués pour l'encapsulation d'IVM par rapport à ceux plus solubles dans l'eau comme la N-methyl-2-pyrrolidone et la 2-pyrrolidone. Ces systèmes représentent donc une alternative intéressante par rapport aux formulations conventionnelles d'IVM / In situ forming injectable systems have been used in the past years to obtain sustained drug release formulations which are easy to prepare. These systems using biocompatible solvents and biodegradable polymers are liquids (solutions or emulsions) that upon injection on the body lead to solid implants (ISI) or microparticles (ISM). These systems are formed in contact with water body fluids by polymer precipitation from the polymeric solution. In this work, ISI and ISM made from lactide and/or glycolide polymers (PLA and PLGA) and different biocompatible solvents were performed to obtain sustained release of ivermectin (IVM), an antiparasitic drug with a low oral bioavailability. In vitro and in vivo drug release profiles from these systems were compared with those from microparticles obtained by the classical simple emulsion/solvent evaporation method, which is difficult to propose in industry because of its multiple steps, high cost and the solvent toxicity. Drug release from simple emulsion/solvent evaporation microparticles was affected by the strong polymer/drug interactions and porosity. Concerning to in situ forming systems, the rate of IVM release was dependent on solvent water solubility and solvent/polymer interactions. The nature of the external phase, water (ISM-O/W) or oil (ISM-O/O), the water solubility of the solvent in the internal phase, phase affinity and IVM/phase affinity determined drug release from ISM. The good stability, the in vitro and in vivo sustained release and the low burst effect of IVM, indicated that ISI and ISM formulated from low hydrosoluble biocompatible solvents such as triacetin are more appropriated to IVM formulation instead of those based on more hydrophilic solvent (N-methyl-2-pyrrolidone and 2-pyrrolidone). These systems are an interesting alternative to conventional IVM formulations

Previous research has shown that Generalized Anxiety Disorder (GAD) is related to stress levels, poor sleep quality, female gender, and younger age. Therefore, the aim of this study was to examine if stress level, sleep quality, gender, and age could predict an increased risk of developing GAD. We hypothesized that increased levels of stress, poorer sleep quality, female gender and younger age predicted an increased risk of developing GAD. A quantitative data collection was performed. The questionnaire was presented on Facebook and was sent by email to contacts at “Blekinge Tekniska Högskola” and “Telenor Connexion” who then forwarded the survey to their colleagues. This self-assessment survey was based on three measuring instruments “Generalized Anxiety Disorder 7 item Scale” (GAD-7),” Karolinska Exhaustion Disorder Scale” (KEDS) and” Insomnia Severity Index” (ISI). A total of 154 participants (93 women, 61 men), were included in the study. The results from the study showed that stress level and age predicted an increased risk of suffering from GAD, where the variable stress level strongest predicted the risk of developing GAD. It could be concluded that stress level and age could predict an increased risk of developing GAD. / Tidigare forskning har visat att generaliserat ångestsyndrom (GAD) är relaterat till stress, sämre sömnkvalitet, kvinnligt kön och lägre åldrar. Därmed var syftet med föreliggande studie att undersöka om stressnivå, sömnkvalitet, kön och ålder kunde predicera en ökad risk för GAD. Studiens hypotes var att ökade nivåer av stress, sämre sömnkvalitet, kvinnligt kön och yngre ålder predicerade en ökad risk att drabbas av GAD. En kvantitativ datainsamling utfördes genom insamling från sociala medier såsom Facebook samt via email till kontaktpersoner från ”Blekinge Tekniska Högskola” och ”Telenor Connexion” som i sin tur vidarebefordrade enkäten till sina arbetskollegor. Enkäten som skickades ut var ett självskattningsformulär som baserades på de tre mätinstrumenten “Generalized Anxiety Disorder 7 item Scale” (GAD-7),” Karolinska Exhaustion Disorder Scale” (KEDS) and ”Insomnia Severity Index” (ISI). Totalt deltog 154 personer (93 kvinnor, 61 män). Resultatet från studien visade att prediktorerna stressnivå och ålder kunde predicera en ökad risk att drabbas av GAD, där stressnivå i störst utsträckning kunde predicera GAD. Sammanfattningsvis kunde man dra slutsatsen att stressnivå och ålder kunde predicera en ökad risk för att utveckla GAD.