Avatar modeling: a telepresence study with natural user interface

Dissertação para obtenção do Grau de Mestre em Engenharia Electrotécnica e de Computadores

Caracterització d'oscil·ladors basats en CMOS-M/NEMS i la seva aplicació com a sensors de massa

El present projecte tracta sobre la caracterització d'oscil·ladors basats en ressonadors micro/nanoelectromecànics (M/NEMS) i la seva aplicació com a sensors de massa. Els oscil·ladors utilitzats es basen en un pont i una palanca ressoants M/NEMS, integrats en tecnologia CMOS. En primer lloc s'ha fet una introducció teòrica als conceptes utilitzats per a entendre el funcionament i la caracterització dels dispositius. A continuació s'han realitzat proves per tal de caracteritzar els paràmetres importants per a l'ús dels oscil·ladors com a sensors de massa, com la seva estabilitat en freqüència. Per acabar s'han aplicat aquests sensors en la caracterització i modelització del flux de massa a través d'obertures de dimensions micromètriques.

Binding under Conflict Conditions: State-Space Analysis of Multivariate EEG Synchronization.

Real-world objects are often endowed with features that violate Gestalt principles. In our experiment, we examined the neural correlates of binding under conflict conditions in terms of the binding-by-synchronization hypothesis. We presented an ambiguous stimulus ("diamond illusion") to 12 observers. The display consisted of four oblique gratings drifting within circular apertures. Its interpretation fluctuates between bound ("diamond") and unbound (component gratings) percepts. To model a situation in which Gestalt-driven analysis contradicts the perceptually explicit bound interpretation, we modified the original diamond (OD) stimulus by speeding up one grating. Using OD and modified diamond (MD) stimuli, we managed to dissociate the neural correlates of Gestalt-related (OD vs. MD) and perception-related (bound vs. unbound) factors. Their interaction was expected to reveal the neural networks synchronized specifically in the conflict situation. The synchronization topography of EEG was analyzed with the multivariate S-estimator technique. We found that good Gestalt (OD vs. MD) was associated with a higher posterior synchronization in the beta-gamma band. The effect of perception manifested itself as reciprocal modulations over the posterior and anterior regions (theta/beta-gamma bands). Specifically, higher posterior and lower anterior synchronization supported the bound percept, and the opposite was true for the unbound percept. The interaction showed that binding under challenging perceptual conditions is sustained by enhanced parietal synchronization. We argue that this distributed pattern of synchronization relates to the processes of multistage integration ranging from early grouping operations in the visual areas to maintaining representations in the frontal networks of sensory memory.

GNSS array: diseño de una antena con polarización circular

Aquest projecte es centra en el disseny d’una antena microstrip per a GNSS. Una antena per a GNSS ha de tenir adaptació de impedància d’entrada i polarització circular a dretes, com a principals especificacions, en el rang de 1.15-1.6 GHz. El tipus d’alimentació d’una antena microstrip amb el major ample de banda d’adaptació és l’alimentació mitjançant acoblament per apertura. Si a l’antena s’introdueixen dos apertures de forma ortogonal, alimentades amb un desfasament de 90º entre elles, s’aconsegueix polarització circular. L’opció de separar les apertures redueix la transferència de potència entre elles, i disminueix el guany de polarització creuada. La xarxa d’alimentació dissenyada és un divisor de Wilkinson amb una línia de λ/4 a la freqüència central, encara que el desfasament als extrems de la banda no sigui de 90º. Com a xarxa d’alimentació es va provar un hibrid de 90º, però l’elevat valor del paràmetre S21 de l’antena impossibilita l’adaptació a l’entrada del hibrid.

Control of optical fields and single photon emitters by advanced nanoantenna structures

The control of optical fields on the nanometre scale is becoming an increasingly important tool in many fields, ranging from channelling light delivery in photovoltaics and light emitting diodes to increasing the sensitivity of chemical sensors to single molecule levels. The ability to design and manipulate light fields with specific frequency and space characteristics is explored in this project. We present an alternative realisation of Extraordinary Optical Transmission (EOT) that requires only a single aperture and a coupled waveguide. We show how this waveguide-resonant EOT improves the transmissivity of single apertures. An important technique in imaging is Near-Field Scanning Optical Microscopy (NSOM); we show how waveguide-resonant EOT and the novel probe design assist in improving the efficiency of NSOM probes by two orders of magnitude, and allow the imaging of single molecules with an optical resolution of as good as 50 nm. We show how optical antennas are fabricated into the apex of sharp tips and can be used in a near-field configuration.

Marker-free phase nanoscopy

We introduce a microscopic method that determines quantitative optical properties beyond the optical diffraction limit and allows direct imaging of unstained living biological specimens. In established holographic microscopy, complex fields are measured using interferometric detection, allowing diffraction-limited phase measurements. Here, we show that non-invasive optical nanoscopy can achieve a lateral resolution of 90 nm by using a quasi-2 pi-holographic detection scheme and complex deconvolution. We record holograms from different illumination directions on the sample plane and observe subwavelength tomographic variations of the specimen. Nanoscale apertures serve to calibrate the tomographic reconstruction and to characterize the imaging system by means of the coherent transfer function. This gives rise to realistic inverse filtering and guarantees true complex field reconstruction. The observations are shown for nanoscopic porous cell frustule (diatoms), for the direct study of bacteria (Escherichia coil), and for a time-lapse approach to explore the dynamics of living dendritic spines (neurones).

The Possibilities and Dosimetric Limitations of MLC-Based Intensity-Modulated Radiotherapy Delivery and Optimization Techniques

The use of intensity-modulated radiotherapy (IMRT) has increased extensively in the modern radiotherapy (RT) treatments over the past two decades. Radiation dose distributions can be delivered with higher conformality with IMRT when compared to the conventional 3D-conformal radiotherapy (3D-CRT). Higher conformality and target coverage increases the probability of tumour control and decreases the normal tissue complications. The primary goal of this work is to improve and evaluate the accuracy, efficiency and delivery techniques of RT treatments by using IMRT. This study evaluated the dosimetric limitations and possibilities of IMRT in small (treatments of head-and-neck, prostate and lung cancer) and large volumes (primitive neuroectodermal tumours). The dose coverage of target volumes and the sparing of critical organs were increased with IMRT when compared to 3D-CRT. The developed split field IMRT technique was found to be safe and accurate method in craniospinal irradiations. By using IMRT in simultaneous integrated boosting of biologically defined target volumes of localized prostate cancer high doses were achievable with only small increase in the treatment complexity. Biological plan optimization increased the probability of uncomplicated control on average by 28% when compared to standard IMRT delivery. Unfortunately IMRT carries also some drawbacks. In IMRT the beam modulation is realized by splitting a large radiation field to small apertures. The smaller the beam apertures are the larger the rebuild-up and rebuild-down effects are at the tissue interfaces. The limitations to use IMRT with small apertures in the treatments of small lung tumours were investigated with dosimetric film measurements. The results confirmed that the peripheral doses of the small lung tumours were decreased as the effective field size was decreased. The studied calculation algorithms were not able to model the dose deficiency of the tumours accurately. The use of small sliding window apertures of 2 mm and 4 mm decreased the tumour peripheral dose by 6% when compared to 3D-CRT treatment plan. A direct aperture based optimization (DABO) technique was examined as a solution to decrease the treatment complexity. The DABO IMRT technique was able to achieve treatment plans equivalent with the conventional IMRT fluence based optimization techniques in the concave head-and-neck target volumes. With DABO the effective field sizes were increased and the number of MUs was reduced with a factor of two. The optimality of a treatment plan and the therapeutic ratio can be further enhanced by using dose painting based on regional radiosensitivities imaged with functional imaging methods.

Palynotaxonomy of Vernonanthura H. Rob. (Vernonieae, Asteraceae) species from Southeast Brazil

The present work studied the pollinic characteristics of 22 species of Vernonanthura from Southeast Brazil. The pollen grains were acetolysed, measured, described and ilustrated under light, scanning and transmission electron microscopy. Based on the results, Vernonanthura was considered an euripolinic genus as pollen grains presented distinctive characteristics, mainly related to the ornamentation, the size and apertures of the pollen grains, which may serve as a further tool in the delimitation of the species.

Pollen morphology of species of Hortia (Rutaceae)

A palinological study covering all 10 species of the Neotropical genus Hortia Vand. (Rutaceae) was conducted. Pollen grains were collected from herbarium exsiccates, acetolysed and mounted in glycerine jelly on glass slides. The grains were studied under light and scanning electron microscopy, including measurements of polar and equatorial diameters, shape of the grains, number and shape of apertures, and thickness of the exine. The results demonstrated that the genus is stenopalynous, with pollen grains in monads, subprolate to prolate, 3-colporate, with very thick exine and a psilate-perforate pattern of ornamentation. Pollen grains of all species revealed a great similarity, with few variations in the pattern of ornamentation of exine, number and form of apertures and measurements. Although well-characterized palinologycally, pollen features did not furnish relevant information on the position of Hortia into an intrafamilial phylogeny.

Confocal and two-photon microscopy : image enhancement /

Confocal and two-photon microcopy have become essential tools in biological research and today many investigations are not possible without their help. The valuable advantage that these two techniques offer is the ability of optical sectioning. Optical sectioning makes it possible to obtain 3D visuahzation of the structiu-es, and hence, valuable information of the structural relationships, the geometrical, and the morphological aspects of the specimen. The achievable lateral and axial resolutions by confocal and two-photon microscopy, similar to other optical imaging systems, are both defined by the diffraction theorem. Any aberration and imperfection present during the imaging results in broadening of the calculated theoretical resolution, blurring, geometrical distortions in the acquired images that interfere with the analysis of the structures, and lower the collected fluorescence from the specimen. The aberrations may have different causes and they can be classified by their sources such as specimen-induced aberrations, optics-induced aberrations, illumination aberrations, and misalignment aberrations. This thesis presents an investigation and study of image enhancement. The goal of this thesis was approached in two different directions. Initially, we investigated the sources of the imperfections. We propose methods to eliminate or minimize aberrations introduced during the image acquisition by optimizing the acquisition conditions. The impact on the resolution as a result of using a coverslip the thickness of which is mismatched with the one that the objective lens is designed for was shown and a novel technique was introduced in order to define the proper value on the correction collar of the lens. The amoimt of spherical aberration with regard to t he numerical aperture of the objective lens was investigated and it was shown that, based on the purpose of our imaging tasks, different numerical apertures must be used. The deformed beam cross section of the single-photon excitation source was corrected and the enhancement of the resolution and image quaUty was shown. Furthermore, the dependency of the scattered light on the excitation wavelength was shown empirically. In the second part, we continued the study of the image enhancement process by deconvolution techniques. Although deconvolution algorithms are used widely to improve the quality of the images, how well a deconvolution algorithm responds highly depends on the point spread function (PSF) of the imaging system applied to the algorithm and the level of its accuracy. We investigated approaches that can be done in order to obtain more precise PSF. Novel methods to improve the pattern of the PSF and reduce the noise are proposed. Furthermore, multiple soiu'ces to extract the PSFs of the imaging system are introduced and the empirical deconvolution results by using each of these PSFs are compared together. The results confirm that a greater improvement attained by applying the in situ PSF during the deconvolution process.

Examining the impact of trait anxiety on the recognition of facial emotional expressions

Question : Cette thèse comporte deux articles portant sur l’étude d’expressions faciales émotionnelles. Le processus de développement d’une nouvelle banque de stimuli émotionnels fait l’objet du premier article, alors que le deuxième article utilise cette banque pour étudier l’effet de l’anxiété de trait sur la reconnaissance des expressions statiques. Méthodes : Un total de 1088 clips émotionnels (34 acteurs X 8 émotions X 4 exemplaire) ont été alignés spatialement et temporellement de sorte que les yeux et le nez de chaque acteur occupent le même endroit dans toutes les vidéos. Les vidéos sont toutes d’une durée de 500ms et contiennent l’Apex de l’expression. La banque d’expressions statiques fut créée à partir de la dernière image des clips. Les stimuli ont été soumis à un processus de validation rigoureux. Dans la deuxième étude, les expressions statiques sont utilisées conjointement avec la méthode Bubbles dans le but d’étudier la reconnaissance des émotions chez des participants anxieux. Résultats : Dans la première étude, les meilleurs stimuli ont été sélectionnés [2 (statique & dynamique) X 8 (expressions) X 10 (acteurs)] et forment la banque d’expressions STOIC. Dans la deuxième étude, il est démontré que les individus présentant de l'anxiété de trait utilisent préférentiellement les basses fréquences spatiales de la région buccale du visage et ont une meilleure reconnaissance des expressions de peur. Discussion : La banque d’expressions faciales STOIC comporte des caractéristiques uniques qui font qu’elle se démarque des autres. Elle peut être téléchargée gratuitement, elle contient des vidéos naturelles et tous les stimuli ont été alignés, ce qui fait d’elle un outil de choix pour la communauté scientifique et les cliniciens. Les stimuli statiques de STOIC furent utilisés pour franchir une première étape dans la recherche sur la perception des émotions chez des individus présentant de l’anxiété de trait. Nous croyons que l’utilisation des basses fréquences est à la base des meilleures performances de ces individus, et que l’utilisation de ce type d’information visuelle désambigüise les expressions de peur et de surprise. Nous pensons également que c’est la névrose (chevauchement entre l'anxiété et la dépression), et non l’anxiété même qui est associée à de meilleures performances en reconnaissance d’expressions faciales de la peur. L’utilisation d’instruments mesurant ce concept devrait être envisagée dans de futures études.

Design Considerations of Sonar Projector Arrays with Improved Performance

Systems which employ underwater acoustic energy for observation or communication are called sonar systems. The active and passive sonars are the two types of systems used for the detection and localisation of targets in underwater. Active sonar involves the transmission of an acoustic signal which, when reflected from a target, provides the sonar receiver with a basis for the detection and estimation. Passive sonar bases its detection and estimation on sounds which emanate from the target itself--Machinery noise, flow noise, transmission from its own active sonar etc.Electroacoustic transducers are used in sonar systems for the transmission and detection of acoustic energy. The transducer which is used for the transmission of acoustic energy is called projector and the one used for reception is called hydrophone. Since a single transducer is not sufficient enough for long range and directional transmission, a properly distributed array of transducers are to be used [9-11].The need and requirement for spatial processing to generate the most favourable directivity patterns for transducer systems used in underwater applications have already been analysed by several investigators [12-21].The desired directivity pattern can be either generated by the use of suitable focussing techniques or by an array of non-directional sensor elements, whose arrangements, spacing and the mode of excitation provide the required radiation pattern or by the combination of these.While computing that the directivity pattern, it is assumed strength of the elements are unaffected by the the source acoustic pressure at each source. However, in closely packed a r r a y s , the acoustic interaction effects experienced among the elements will modify the behaviour of individual elements and in turn will reduce the acoust ic source leve 1 wi t h respect to the maximum t heoret i cal va 1ue a s well as degrade the beam pa t tern. Th i s ef fect shou 1d be reduced in systems that are intended to generate high acoustic power output and unperturbed beam patterns [2,22-31].The work herein presented includes an approach for designing efficient and well behaved underwater transd~cer arrays, taking into account the acoustic interaction effect experienced among the closely packed multielement arrays.Architectural modifications reducing the interaction effect different radiating apertures.

Wechselwirkung von im NANOJET erzeugten Teilchen mit Polymeren und biologischen Objekten

Am Institut für Mikrostrukturtechnologie und Analytik wurde eine neue Technik entwickelt, die neue Anwendungen und Methoden der Mikro- und Nanostrukturierung auf Basis eines neuen Verfahrens erschlossen hat. NANOJET führt über die passive Rastersondenmikroskopie hinaus zu einem vielseitigen, aktiven Bearbeitungswerkzeug auf der Mikro- und Nanometerskala. NANOJET (NANOstructuring Downstream PlasmaJET) ist eine aktive Rasterkraft-Mikroskopie-Sonde. Radikale (chemisch aktive Teilchen, die ein ungepaartes Valenzelektron besitzen) strömen aus dem Ende einer ultradünnen, hohlen Rasterkraftmikroskop-Spitze. Dadurch wird es möglich, über die übliche passive Abtastung einer Probenoberfläche hinausgehend, diese simultan und in-situ durch chemische Reaktionen zu verändern. Die Abtragung von Material wird durch eine chemische Ätzreaktion erreicht. In dieser Arbeit wurde zum größten Teil Photoresist als Substrat für die Ätzexperimente verwendet. Für das Ätzen des Resists wurden die Atome des Fluors und des Sauerstoffs im Grundzustand als verantwortlich identifiziert. Durch Experimente und durch Ergänzung von Literaturdaten wurde die Annahme bestätigt, dass Sauerstoffradikale mit Unterstützung von Fluorradikalen für die hohen erzielten Ätzraten verantwortlich sind. Die Beimischung von Fluor in einem Sauerstoffplasma führt zu einer Verringerung der Aktivierungsenergie für die Ätzreaktion gegenüber Verwendung reinen Sauerstoffs. In weiterer Folge wurde ein Strukturierungsverfahren dargestellt. Hierbei wurden "geformte Kapillaren" (mikrostrukturierte Aperturen) eingesetzt. Die Herstellung der Aperturen erfolgte durch einen elektrochemischen Ätzstop-Prozess. Die typische Größe der unter Verwendung der "geformten Kapillaren" geätzten Strukturen entsprach den Kapillarenöffnungen. Es wurde ein Monte-Carlo Simulationsprogramm entwickelt, welches den Transport der reaktiven Teilchen in der langen Transportröhre simulierte. Es wurde sowohl die Transmission der Teilchen in der Transportröhre und der Kapillare als auch ihre Winkelverteilung nach dem Verlassen der Kapillare berechnet. Das Aspektverhältnis der Röhren hat dabei einen sehr starken Einfluss. Mit einem steigenden Aspektverhältnis nahm die Transmission exponentiell ab. Die geschaffene experimentelle Infrastruktur wurde genutzt, um auch biologische Objekte zu behandeln und zu untersuchen. Hierfür wurde eine neue Methodik entwickelt, die eine dreidimensionale Darstellung des Zellinneren erlaubt. Dies wurde durch die kontrollierte Abtragung von Material aus der Zellmembran durchgeführt. Die Abtragung der Zellmembran erfolgte mittels Sauerstoffradikalen, die durch eine hohle Spitze lokalisiert zum Ort der Reaktion transportiert wurden. Ein piezoresistiver Cantilever diente als Sensor in dem zur Bildgebung eingesetzten RKM. Das entwickelte Verfahren ermöglicht es nun erstmals, schonend Zellen zu öffnen und die innen liegenden Organellen weiter zu untersuchen. Als Nachweis für weitere Verwendungsmöglichkeiten des NANOJET-Verfahrens wurde auch Knochenmaterial behandelt. Die Ergebnisse dieser Experimente zeigen klar, dass das Verfahren für vielfältige biologische Materialien verwendbar ist und somit nun ein weiter Anwendungskreis in der Biologie und Medizin offen steht.

Methylammonium antimony sulfide

Bis(methylammonium) octaantimony(III) dodecasulfide persulfide, (CH3NH3)(2)[Sb8S12(S-2)], contains pairs of [Sb4S7](2-) chains joined through an unusual persulfide bond to create infinite double [Sb8S14](2-) chains. The double chains are interlocked by longer Sb center dot center dot center dot S interactions to form sheets approximately parallel to the (101) crystallographic plane. Methylammonium cations, formed by decomposition of 2-methylpropane-1,2-diamine during the synthesis, are located in large (Sb8S10) hetero-ring apertures created within the double chains.

The effects of a pre-movement delay on the kinematics of prehension in middle childhood

The present study examined the effects of a pre-movement delay on the kinematics of prehension in middle childhood. Twenty-five children between the ages of 5 and 11 years made visually open-loop reaches to two different sized objects at two different distances along the midline. Reaches took place either (i) immediately, or (ii) 2 s after the occlusion of the stimulus. In all age groups, reaches following the pre-movement delay were characterised by longer movement durations, lower peak velocities, larger peak grip apertures and longer time spent in the final slow phase of the movement. This pattern of results suggests that the representations that control the transport and grasp component are affected similarly by delay, and is consistent with the results previously reported for adults. Such representations therefore appear to develop before the age of 5. (C) 2004 Elsevier B.V. All rights reserved.