Disertacijoje sprendžiama papildomų ekranų įtakos meandrinių lėtinimo sistemų dažninėms savybėms įvertinimo problema. Pagrindiniai tyrimo objektai – planariosios meandrinės lėtinimo sistemos (PMLS) su papildomais ekranais, jų modeliai ir analizės bei sintezės metodai. Darbo tikslas – ištirti PMLS su papildomais ekranais, sukurti naujus modelius ir jų tyrimo metodikas leidžiančias įvertinti lėtinimo sistemų kraštų bei galų efektus, sukurti tokių lėtinimo sistemų parametrinės sintezės metodiką. / The dissertation investigates the issues of influence of additional shields on frequency characteristics of meander slow-wave system. The main objects of research include planar meander slow-wave systems with additional shields, their models and the methods of analysis and synthesis. The primary purpose of this dissertation is to investigate the planar meander slow-wave systems with additional shields by creating new models and their investigation techniques which allow to evaluate the effects on the edges and ends of slow-wave systems and create the technique for parametric synthesis of such slow-wave systems.

Aging and Alzheimer’s disease (AD), are associated with disabling sleep and cognitive deficits. Specifically, aging and Alzheimer’s disease is associated with reduced quantity and quality of the deepest stage of sleep, called slow-wave-sleep (SWS). Interestingly, SWS has been implicated in hippocampus-dependent memory in mice. More importantly, sleep deprivation, aging, and AD are all associated with deficits in memory. Therefore, I hypothesize that, in aging and AD, the sleep deficits are, at least in part, responsible for memory impairments and increasing the quantity and quality of SWS will reverse these memory deficits. I first developed mouse models of SWS enhancement in aging and AD. Chemogenetic activation of the parafacial zone GABAergic neurons enhances SWS in aged mice as previously described in adult mice. Similarly, in AD mice, SWS enhancement is as effective as in littermate wild-type controls. Then, I used these mouse models to characterize the role of SWS in memory using novel gain-of-sleep experiments. I found that acute SWS enhancement: 1) reduce spatial memory in adult mice and 2) failed to improve spatial memory in aged mice. In a preliminary study, acute SWS enhancement seems to improve contextual memory in AD mice. Collectively, my work provides a novel mouse model of SWS enhancement in aging and AD, offering a pivotal tool to study the role of SWS in physiological functions and neurodegenerative diseases. Furthermore, my results suggest that acute SWS enhancement does not benefit the behavioral manifestation of memory consolidation in adult mice and aged mice.

This study provides the baseline and initial assessment of the napping habits of the United States Military Academy Class of 2007. This portion of a four-year longitudinal study examines data collected on 62 Cadets over 32 days from 4 October 2004 to 4 November 2004 using actigraphy data and sleep logs. Data were stratified and cleaned in accordance with nap infrastructure. A total of 607 naps were reported for a total of 73.3 hours of additional sleep. Naps ranged from 15 minutes to six hours and occurred most frequently on weekdays. This finding contrasts with research of other samples of adolescent college students. Weekend naps were shorter in duration than weekday naps. This finding was also a departure from current scientific nap research findings. Consistent with other research, most naps were between 30 minutes to one and one half hours in length. Frequency and duration of naps were greatest on Wednesdays. The primary type of nap taken was restorative, as opposed to appetitive or prophylactic in nature. Afternoon naps were more prevalent than morning naps, possibly reflecting Cadet class schedule rather than sleep need. Suggestions for additional research are proposed.

L’objectif de cette action R&T CNES est le développement en technologie intégrée SiGe BiCMOS d’un core-chip MMIC pour les antennes à formation de faisceaux. Les nouvelles solutions pour les charges satellites développées pour les applications télécom notamment ont besoin d’être de plus en plus flexibles. Cela passe par la mise en place d’un très grand nombre de points de contrôle RF ‘Amplitude/Phase’ qui alimentent les antennes actives. Il faut donc de nouvelles solutions pour optimiser ces fonctions. Ces solutions doivent répondre à plusieurs critères : être compactes, diminuer la consommation DC et conserver les mêmes niveaux de performance en termes de gain, résolution et linéarité que les solutions déjà en place. Dans ce contexte, notre projet de recherche a porté sur le développement de circuits déphaseurs et atténuateurs en technologie SiGe. Une étude préliminaire a permis d’évaluer la technologie en réalisant un premier run comprenant des cellules de déphasage et d’atténuation élémentaires. Des lignes de transmission de type Slow Wave Lines ont également été intégrées afin de montrer leur potentiel pour des applications futures. Ces premiers résultats ont conduits à réaliser un second run comprenant des circuits plus avancés ainsi que le test d’une nouvelle technique pour le design des transistors : le body floating. Cette technique nous a permis de diminuer les pertes de nos circuits tout en améliorant la linéarité. Un troisième run incluant un déphaseur et un atténuateur 4 bits a permis de confirmer les modèles de simulations et le potentiel des circuits MMIC en technologie SiGe. Un dernier run a enfin permis de réaliser un nouveau type de SWL et de réaliser des solutions alternatives aux circuits classiques basées sur ces dernières. / This R&T CNES project concerns the design and realization of a Core-chip MMIC system integrated in SiGe BiCMOS technology. The MMIC core-chip system is dedicated to the beamforming for the active satellite antenna. The new solutions for the satellite payloads being developed for telecommunication applications need an increased flexibility at all the levels. More precisely, the system of active antennas allowing an adjustment by real-time electronic command of the terrestrial covered area offers an optimized response for the communication link budget. This performance has a cost: the necessity of a very large number of RF control points "amplitude / phase" of the beamforming equipment which power the active antenna matrix elements. So, it becomes mandatory to bring a new solution to optimize this function. The main challenges are: increasing the functions integration, decreasing the DC power consumption and keeping the RF performances in terms of gain, resolution and linearity.

A true time delay multi-bit MEMS phase shifter topology based on impedance-matched slow-wave CPW sections on a 500µm thick quartz substrate is presented. Design equations based on the approximate model for a distributed line is derived and used in optimization of the unit cell parameters. A semi-lumped model for the unit cell is derived and its equivalent circuit parameters are extracted from measurement and EM simulation data. This unit cell model can be cascaded to accurately predict N-section phase shifter performance. Experimental data for a 4.6mm long 4-bit device shows a maximum phase error of 5.5° and S11 less than -21dB from 1-50GHz. A reconfigurable MEMS transmission line based on cascaded capacitors and slow-wave sections has been developed to provide independent Zo - and β-tuning. In the Zo-mode of operation, a 7.4mm long line provides Zo-tuning from 52 to 40Ω (+/-2Ω) with constant phase between the states through 50GHz. The same transmission line is reconfigured by addressing the MEM elements differently and experimental data for a 1-bit version shows 358°/dB (or 58°/mm) with S11 less than -25dB at 50GHz. The combined effect of Zo- and β-tuning is also realized using a 5-bit version. An electronically tunable TRL calibration set that utilizes a 4-bit true time delay MEMS phase shifter topology, is demonstrated. The accuracy of the tunable TRL is close to a conventional multi-line TRL calibration and shows a maximum error bound of 0.12 at 40GHz. The Tunable TRL method provides for an efficient usage of wafer area while retaining the accuracy associated with the TRL technique, and reduces the number of probe placements.

Naturally fractured reservoirs have attracted an increased interest of exploration and production geophysics in recent years. In many instances, natural fractures control the permeability of the reservoir, and hence the ability to find and characterize fractured areas of the reservoir represents a major challenge for seismic investigations. In fractured and porous reservoirs the fluid affects elastic anisotropy of the rock and also causes significant frequency dependent attenuation and dispersion. In this study we develop a mathematical model for seismic wave attenuation and dispersion in a porous medium in a porous medium with aligned fractured, caused by wave induced fluid flow between pores and fractures. In this work fractures in the porous rock are modelled as very thin and highly porous layers in a porous background. Dry highly porous materials have low elastic moduli; thus dry skeleton of our system contains thin and soft layers, and is described by linear slip theory. The fluid saturated rock with high-porasity layers is described by equations of poroelasticity with periodically varying coefficients. These equations are analyzed using propagator matrix approach commonly used to study effective properties of layered system. This yields a dispersion equation for a periodically layered saturated porous medium taking into account fluid communication between pore spaces of the layers. Taking in this dispersion equation a limit of small thickness for high-porosity layers gives the velocity and attenuation as a function of frequency and fracture parameters. The results of this analysis show that porous saturated rock with aligned fractures exhibits significant attenuation and velocity dispersion due to wave induced fluid flow between pores and fractures. / At low frequencies the material properties are equal to those obtained by anisotropic Gassmann theory applied to a porous material with linear-slip, interfaces. At high frequencies the results are equivalent to those for fractures with vanishingly small normal slip in a solid (non-porous) background. The characteristic frequency of the attenuation and dispersion depends on the background permeability, fluid viscosity, as well as fracture density and spacing. The wave induced fluid flow between pores and fractures considered in this work has exactly the same physical nature as so-called squirt flow, which is widely believed to by a major cause of seismic attenuation. Hence, the present model can be viewed as a new model of squirt-flow attenuation, consistent with Biot’s theory of poroelasticity. The theoretical results of this work are also limited by the assumption of periodic distribution of fractures. In reality fractures may be distributed in a random fashion. Sensitivity of our results to the violation of the periodicity assumption was examined numerically using reflectivity modelling for layered poroelastic media. Numerical experiments for a random distribution of fractures of the same thickness still show surprisingly good agreement with theoretical results obtained for periodic fractures. However this agreement may break down if fracture properties are allowed to vary from fracture to fracture. The results of this thesis show how to compute frequency dependences of attenuation and velocity caused by wave induced fluid flow between pores and fractures. These results can be used to obtain important parameters of fractured reservoirs, such as permeability and fracture weakness, from attenuation measurements. The major requirement for the success of such an approach is that measurements must be made in over a relatively broad frequency range.

Aim and tasks of the work. The aim of this work is to investigate insufficiently analyzed variants of the electrodynamic super-wide-band slow-wave structures, create their models, improve methods of analysis, analyze properties of the systems and reveal potentiality of the traveling-wave cathode-ray tubes, slow-wave structures. In order to achieve the aim it is necessary: 1. To improve method for evaluation of non-linear distortions in the traveling-wave cathode-ray tubes and reveal possibilities of reduction of non-linear distortions. 2. To create models of the insufficiently analyzed variants of slow-wave structures and reveal properties of the slow-wave structures. 3. To reveal influence of periodical non-homogeneities on properties of slow-wave structures, simulate and reveal influence of transitions to properties of slow-wave structures and traveling-wav cathode-ray tubes. 4. To make investigation of potentiality of slow-wave structures and traveling-wave cathode-ray tubes and select variants of slow-wave structures that can guarantee wide band and high operating speed of the traveling-wave cathode-ray tubes. Scientific novelty and practical value. Models of insufficiently simulated slow-wave structures were created and their properties were analyzed. According to analysis and modeling results, variants of systems were selected that can guarantee the wide pass-band and high operating speed of the traveling-wave cathode-ray tubes. Using finite element method calculation... [to full text]

Aim and tasks of the work. The aim of this work is to investigate insufficiently analyzed variants of the electrodynamic super-wide-band slow-wave structures, create their models, improve methods of analysis, analyze properties of the systems and reveal potentiality of the traveling-wave cathode-ray tubes, slow-wave structures. In order to achieve the aim it is necessary: 1. To improve method for evaluation of non-linear distortions in the traveling-wave cathode-ray tubes and reveal possibilities of reduction of non-linear distortions. 2. To create models of the insufficiently analyzed variants of slow-wave structures and reveal properties of the slow-wave structures. 3. To reveal influence of periodical non-homogeneities on properties of slow-wave structures, simulate and reveal influence of transitions to properties of slow-wave structures and traveling-wav cathode-ray tubes. 4. To make investigation of potentiality of slow-wave structures and traveling-wave cathode-ray tubes and select variants of slow-wave structures that can guarantee wide band and high operating speed of the traveling-wave cathode-ray tubes. Scientific novelty and practical value. Models of insufficiently simulated slow-wave structures were created and their properties were analyzed. According to analysis and modeling results, variants of systems were selected that can guarantee the wide pass-band and high operating speed of the traveling-wave cathode-ray tubes. Using finite element method calculation... [to full text]

Ce travail se concentre sur la conception de VCO mm-wave pour les applications de Backhaul en BiCMOS 55 nm technologie. Toutes les conceptions de VCO proposées sont par rapport à conventionnel LC-tank oscillateur. La première conception de l'oscillateur proposé fonctionne entre 81-86 GHz. L'innovation est liée à l'utilisation d'une bande coplanaires ondes lentes (S-CPS) comme inducteur différentiel. Grace à facteur de qualité élevé (≈ 33) de S-CPS, le bruit de phase a été amélioré de 20 dBc/Hz à l'offset 10MHz et la consommation d'énergie a été réduite de 14% aussi. La plage de réglage de fréquence (FTR) était de 5,3 GHz seulement. La seconde conception du VCO est sur la base de ligne déphaseur chargé comme un résonateur. Le déphaseur a été conçu en utilisant une topologie dissymétrique de S-CPS, afin de parvenir à une meilleure FTR. Mais la performance réalisée de VCO n'a pas été beaucoup améliorée en raison de la capacité parasite en charge. Ainsi, avec le même dissymétrique résonateur déphaseur sur la base d'un oscillateur d'onde permanente distribuée a été conçu, ce qui a réduit l'effet de charge et de conduire à une FTR de 8 GHz. Enfin, un buffer moins mm-wave oscillateur stationnaire a été conçu. Dans ce proposé moins oscillateur buffer, il a montré que l’impédance caractéristique de sortie peut être envisagé grâce à un choix judicieux de la position de sortie. Par conséquent, aucun buffer de sortie n’est nécessaire dans la conception proposée, en raison de la flexibilité dans le choix de la position long de sortie de SWO. Cette innovation conduit à deux mérites. Tout d'abord une sortie 50 ohms peut-être synthétisé sans consommation d'énergie supplémentaire et d'autre part la taille est réduite si un réseau d'adaptation est nécessaire pour connecter le VCO à un mélangeur ou un autre bloc de construction du système d'émetteur-récepteur. / This work focuses on the design of mm-wave VCO for Backhaul applications in BiCMOS 55 nm technology. All the proposed VCO designs are compared to the conventional LC-tank oscillator. The first proposed oscillator design operates between 81-86 GHz. The innovation is linked to the use of a slow-wave coplanar strip (S-CPS) as a differential inductor. Thanks to high quality factor (≈ 33) of S-CPS, the phase noise was improved by 20 dBc/Hz at 10 MHz offset and the power consumption was reduced by 14 % as well. The achieved frequency tuning range (FTR) was 5.3 GHz only. The second VCO design is based on loaded line phase shifter as a resonator. The phase shifter has been designed using an unsymmetric topology of S-CPS in order to achieve better FTR. But the achieved VCO performance was not improved a lot due to the loading parasitic capacitance. So, with the same unsymmetric phase shifter based resonator a distributed standing wave oscillator was designed, which reduced the loading effect and lead to a FTR of 8 GHz. Finally, a buffer less mm-wave standing wave oscillator was designed. In this proposed buffer less oscillator it is shown that any output characteristic impedance can be envisaged thanks to a careful choice of the output position. Hence, no output buffer is needed in the proposed design, due to the flexibility in choosing the output position along the SWO. This innovation leads to two merits. Firstly a 50 ohms output can be synthesized without any additional power consumption and secondly the size is reduced if a matching network is needed to connect the VCO to a mixer or another building block of the transceiver system.

Words that deviate in their physical characteristics from their surrounding lead to enhanced recall memory, a pattern known as the Von Restorff effect. Furthermore, common (high frequency; HF) words are more likely to be recalled than uncommon (low frequency; LF) words when they occur in pure lists, while this pattern is reversed in mixed lists of both HF and LF words. This study investigated whether the Von Restorff effect and the reversal of word frequency effects in mixed lists, which may both be explained by enhanced perceived distinctiveness, are associated with common underlying brain processes. Event-related potentials (ERPs) were recorded while participants studied and subsequently recalled 70 word lists using rote memorization strategies. The three list types included (1) 14 regular-sized and one larger word, (2) 14 HF words and one LF word, or (3) 14 LF words and one HF word. The behavioral data showed a typical Von Restorff effect, a word frequency effect, as well as a reversal of the word frequency effect for LF words isolated in HF word lists ("LF isolates"). Larger words and LF isolates elicited a P300, an ERP component associated with subjective distinctiveness, whose amplitude was correlated with subsequent recall for both word types. This indicates that LF isolates were perceived as distinctive, and that this perceived distinctiveness aided subsequent recall in a similar way as for physically deviant words. Both larger words and LF isolates also elicited a left-lateralized slow wave which was larger for subsequently recalled than for not recalled words. This ERP component supposedly reflects item-to-item elaborative processes, indicating that such elaborative processes are enhanced when LF words occur in HF word list. HF words isolated in lists of LF words did not elicit comparable ERP subsequent memory effects. Rather, for these "HF isolates", the N400 was negatively correlated with subsequent recall, an ERP component that reflects semantic integration processes. We conclude that the reversal of the word frequency effect in mixed lists can be explained by a combination of enhanced subjective distinctiveness and enhanced inter-item elaborative processes for LF words that occur in lists of HF words.