Nonphotochemical quenching is an important protective mechanism of photosynthetic proteins against excessive irradiation. In this work, isolation of native light harvesting antennae from alga Chromera velia was optimized using methods of sucrose density centrifugation, isoelectric focusing, ion exchange chromatography and gel electrophoresis. Moreover, the ability of light harvesting antennae to trigger nonphotochemical quenching was studied in vivo and in vitro.

Les interactions entre individus sont un socle vital pour l’organisation des colonies d’abeilles, en particulier lors du recrutement pour le butinage. Outre la communication de la localisation d’une source de nourriture par la fameuse danse, les abeilles recrutées apprennent les caractéristiques de l’odeur des fleurs butinées au cours de transferts de nectar (trophallaxie). Les mécanismes de cet apprentissage ne sont pas encore éclaircis car il est parfois effectif sans aucun transfert de nectar, suggérant que d’autres mécanismes, comme par exemple d’apprentissage social, sont impliqués. Nous avons reproduit cette interaction en laboratoire, suivant un protocole basé sur le conditionnement olfactif appétitif de la réponse d’extension du proboscis (REP). Ici, un composé odorant initialement neutre (Stimulus conditionnel) était associé à un contact avec une congénère (Stimulus Inconditionnel social), sans récompense sucrée. Nos expériences montrent que ce simple contact social entre congénères peut constituer un renforcement pour les abeilles. A la suite de cette association, celles-ci montrent donc des REP à l’odeur préalablement associée au contact social. Nos expériences montrent de plus que des contacts antennaires entre les abeilles sont indispensables à l’efficacité de cet apprentissage social, représentant un indice social tactile. Nous avons alors développé un dispositif permettant d’enregistrer les mouvements des antennes de manière précise et à haute vitesse (90 hz) et étudié les différents facteurs modulant les mouvements antennaires des abeilles. Les abeilles montrent des réponses contrastées et reproductibles à des odeurs de valeurs biologiques différentes. De plus, le couplage de ces enregistrements à des expériences de conditionnement associatif montre que ces réponses antennaires sont plastiques et modifiées par l’expérience des individus. Ce travail a permis de mettre en lumière un nouveau type d’apprentissage social chez les insectes et d’approfondir l’étude des mouvements antennaires comme indicateurs de l’état motivationnel, attentionnel et physiologique des abeilles ainsi que de la valence des stimuli perçus. / In honeybees, interactions between individuals are cornerstones for the organization of the colony, especially during recruitment for foraging. Besides learning the location of a food source thanks to the well-known dance, the recruited bees learn the characteristics of odors of foraged flowers through nectar transfer (trophallaxis). The underlying mechanisms are still unclear because this learning can occur without any nectar transfer, suggesting that other, probably social, learning mechanisms are involved. We reproduced this interaction in the lab, using a protocol based on the appetitive olfactory conditioning of the proboscis extension response (PER). Here, an initially neutral odorant (conditioned stimulus) was associated with a contact with a nestmate (social unconditioned stimulus), without any sugar reward. Our experiments show that this simple social contact between workers can act as a reinforcement for bees. As a result, they show PER to the odor previously associated with a social contact. We further demonstrate that antenna contacts are essential for the effectiveness of this social learning, representing a tactile social cue. We thus developed a system allowing to record bees’ antennal movements accurately and at high frequency (90 hz). We then determined the factors modulating bees’ antennal movements. First, we show that bees display contrasted and reproducible responses to odors of different biological values. Second, the coupling of these recordings with associative conditioning experiments shows that these antennal responses are plastic and modified by individual experience. This work has shed light on a new type of social learning in insects and has furthered our understanding of antennal movements as indicators of the motivational, attentional and physiological state of bees and of the valence of perceived stimuli.

Acquiring GPR data at multiple frequencies is useful because higher-frequency profiles have better spatial resolution, although they suffer from reduced depth penetration. Lower-frequencies can generally resolve to greater depths, but at the cost of spatial resolution. For concise presentation of GPR data, it would be useful to combine the best features of each profile into a composite radargram. This study explores effective ways to present GPR data acquired at multiple frequencies. An example is shown from a survey of hurricane overwash deposits from Santa Rosa Island, Florida. The methodology used to create a composite radargram is dependent on which of two goals the composite radargram is designed to achieve. These goals are broadening the spectral bandwidth of GPR data to increase the effectiveness of deconvolution and enhancing the resolution and depth of GPR data by plotting high-frequency data at early two-way travel times, low-frequency data at late two-way travel times, and using filters to smoothly transition from high-frequency to lower-frequency data. The steps towards creating a composite radargram include: 1) applying standard processing to nominal frequency data sets, 2) creating spatially coincident data sets, 3) equalizing the amplitude spectra among each nominal frequency data set, and 4) summing nominal frequency data sets together. Spectral bandwidth broadening is achieved by applying optical spectral whitening and summing nominal frequency data sets using a single ramped. Deconvolving this composite radargram did not show the same success observed by Booth et al. (2009). Enhancing the resolution and depth of GPR data can be achieved by applying amplitude envelope equalization (AEE) and summation using double ramped filters. AEE calculates the coefficients required to make equivalent average amplitude envelopes for GPR data that has been gained with automatic gain control . Double ramped filters suppress low-frequency energy for two-way travel times when a higher-frequency data set has adequate signal strength and higher frequency energy for two-way travel times when higher- frequency energy exhibits significant attenuation. A composite radargram built with AEE and double ramped filters achieves the goal enhancing resolution and depth of GPR data. Shallow reflections are interpreted as dune and hurricane overwash stratigraphy.

No description available.

No description available.

The hemlock woolly adelgid (HWA), Adelges tsugae Annand (Homoptera: Adelgidae), is forest pest introduced to eastern North America in the early 1950's. Although this pest occurs on both landscape and nursery stock as well as in natural stands of hemlock forest, pesticides are only practical and effective in urban settings. Ecological and economical considerations prevent utilization of chemical treatment in the forest setting, thus biological control is viewed as the most promising option for slowing the spread of HWA. It is essential for researchers to be able to accurately assess the population levels of biocontrol agents after release into the environment. No method currently exists for sampling HWA predators. This project was designed to determine whether two species of predators are able to utilize olfactory cues from eastern hemlock and/or HWA in host-finding. If predators use olfactory cues, we may develop an attractive sythnetic blend of compounds to draw them to a trap, thereby simplifying the sampling and improving its accuracy. To address this question we executed three experiments. The first involved examination of the antennae of the predators for the presence and abundance of olfactory sensilla. The second experiment was designed to detect a behavioral response by the predators following exposure to host volatile compounds. The final experiment involved identifying compounds emitted from eastern hemlock, and the affect of HWA-feeding on volatile emissions. Laricobius nigrinus Fender (Coleoptera: Derodontidae) antennae are densely populated with sensilla, several of which are potentially olfactory in function. In addition, we observed a behavioral response to olfactory cues which included altered flight behavior. However, the behavior was not clearly attraction. Pseudoscymnus tsugae Sasaji and McClure (Coleoptera: Coccinellidae) has few sensilla on a very short antennae and only one type of sensilla possesses wall pores suggestive of an olfactory function. In addition, we did not observe a significant behavioral response to host-volatiles. It seems unlikely that this species uses olfaction in long-range host location. We identified 10 monoterpenes that were consistently expressed in the hemlock volatile profile and were unable to isolate volatile emissions from HWA. There is an increased monoterpene release rate from HWA-infested hemlock foliage as compared to uninfested foliage apparently driven indirectly by HWA through a reduction in new growth at branch tips. In addition there was a slight but statistically significant change in the percent composition of the individual compounds. We see potential in developing a more efficient sampling procedure for L. nigrinus through utilization of olfactory cues. More biological assays must be conducted to determine whether an attractive blend exists and electrophysiological assays are required to isolate physiologically active compounds. However, our data suggest that P. tsugae is not likely to be reliant on olfaction in long-range host location. / Master of Science

A suite of new collision avoidance systems (CAS) is presented for use in heavy vehicles whose structure and size necessarily impede driver visibility is introduced. The main goal of the project is to determine the appropriate use of each of the commercially available technologies and, where possible, produce a low cost variant suitable for use in proximity detection on large mining industry haul trucks. CAS variants produced were subjected to a field demonstration and, linked to the output from the earlier CAS 1 project, (a production high-definition in-cabin video monitor and r/f tagging system). The CAS 2 system used low cost Doppler continuous wave radar antennae coupled to the CAS 1 monitor to indicate the presence of an object moving at any speed above 3 Km/h relative to the antennae. The novelty of the CAS 3 system lies in the design of 3 interconnected, modules. The modules are 8 radar antennae (as used in CAS 2) modules located on the truck, software to interface with the end user (i.e. the drivers of the trucks) and a display unit. Modularisation enables the components to be independently tested, evaluated and replaced when in use. The radar antennae modules and the system as a whole are described together with the empirical tests conducted and results obtained. The tests, drawing on Monte-Carlo simulation techniques, demonstrate both the 'correctness' of the implementations and the effectiveness of the system. The results of the testing of the final prototype unit were highly successful both as a computer simulation level and in practical tests on light vehicles. A number of points, (as a consequence of the field test), are reviewed and their application to future projects discussed.

The brain is incredibly complex, with billions of diverse cells performing a variety of necessary functions. It is fascinating then, that a small group of progenitor cells are capable of generating all of the neural cell types. During development, robust and stable expression of identity factors is necessary for diverse cell fate determination, but progenitor cells must also be flexible to quickly change expression programs in response to developmental cues. The metazoan genome is non-randomly organized, and this organization is thought to underlie cell type specific gene expression programs. However, the process by which genome organization is stabilized, and then reorganized, is not well-understood. A Drosophila neuroblast nuclear factor, Distal antenna (Dan), was previously identified as a key regulator of this process. Downregulation of Dan is necessary for a developmentally-timed genome reorganization in neural progenitors that terminates their competence to specify early-born cell types. Maintaining Dan expression prevents genome reorganization, extending the early competence window, and implicating Dan in the stabilization of the early competence state. The mechanisms through which Dan functions to stabilize the genome architecture is not known. In this work, we take advantage of the Drosophila embryonic ventral nerve cord model system to study Dan and its role in regulating neuroblast competence. We find that Dan, a DNA- binding protein that localizes throughout the nucleus in distinct puncta, coalesces into large, liquid condensates that relocalize to the nuclear periphery when DNA-binding is inhibited. The size of the droplets increases as impairment to the DNA-binding domain increases, suggesting that Da normally exists in a competitive tug-of-war between genome binding and protein condensation at the nuclear periphery. We further find that while Dan is a highly intrinsically disordered protein, formation of the large droplets requires a LARKS domain – a glycine-rich, structural motif that forms kinked beta-sheets associated with labile interactions that underlie phase-separation. In embryos, Dan’s ability to maintain neural progenitor early competence requires both its Pipsqueak motif DNA-binding domain and phase separation properties. Finally, we find that Dan interacts with proteins of the nuclear pore complex. In particular, we find that Elys, a core scaffold protein which has been shown to bind DNA and regulate nuclear architecture, is required for termination of the early competence window. Together, we propose a mechanism by which a single protein can exert opposing forces between DNA binding and self- association to organize progenitor genome architecture and regulate neuronal diversification.

No description available.

[pt] No cenário atual das telecomunicações móveis, os arranjos de antenas voltaram a receber grande atenção dos pesquisadores, especialmente quando esquemas adaptativos de modificação de seus diagramas de radiação são utilizados. Uma das aplicações que exploram o potencial dos arranjos de antenas é o seu uso como forma de aumentar consideravelmente a eficiência espectral dos sistemas móveis atuais e da próxima geração. A outra aplicação em evidência está voltada para sistemas de localização de posição, pois algumas das técnicas conhecidas envolvem a estimação de ângulos-de-chegada usando arranjos de antenas. Diante destas possibilidades, cresce em importância o estudo das variações do canal de propagação rádio móvel no domínio em que o uso dos arranjos de antenas atua: o espacial. O presente trabalho procura contribuir para o contexto em questão, com uma investigação experimental do canal real rádio-móvel nos domínios temporal (retardos) e espacial (ângulos-de-chegada). No que se refere ao contexto nacional, contribuições similares baseadas em simulações já são encontradas; baseadas em medidas não. Em particular, sondagens na faixa de 1,8 GHz em ambientes internos típicos foram realizadas. Duas técnicas distintas de sondagem temporalespacial foram implementadas, tomando por base uma sonda de canal faixa-larga montada e testada com sucesso, como contribuição principal de uma dissertação de mestrado recentemente apresentada por um integrante do mesmo grupo de pesquisa ao qual esta tese está vinculada. Uma das técnicas sintetiza o arranjo realizando as sondagens com uma única antena que é sucessivamente deslocada para ocupar as posições correspondentes às dos elementos do arranjo. A outra técnica emprega um arranjo real. Em ambas, a configuração mais simples para um arranjo foi utilizada: a linear uniforme. As sondagens não forneciam diretamente os espectros espaciais-temporais. As estimativas dos espectros foram processadas posteriormente, aplicando técnicas como o correlograma para o domínio do retardo, e quatro técnicas distintas para o domínio espacial, que foi o foco principal deste trabalho: duas convencionais; e duas paramétricas, com potencial de aumentar a resolução das estimativas, assumindo hipóteses razoáveis sobre as respostas esperadas. De posse das respostas espectrais estimadas, comparações com estimativas teóricas permitiram uma análise de desempenho das técnicas utilizadas. Adicionalmente à investigação experimental do canal espacial, procurou-se verificar o potencial da aplicação da teoria de wavelets ao estudo do canal rádiomóvel. Em especial, uma das principais aplicações daquela teoria foi testada como técnica de pós-processamento das respostas espectrais no domínio do retardo. A supressão de ruído por decomposição wavelet foi aplicada a um vasto conjunto de medidas de canal disponíveis, fruto de trabalhos anteriores do grupo de pesquisa ao qual esta tese está vinculada, com resultados expressivos. / [en] In the present mobile communications scenario, researchers have turned once again special attention to antennae arrays, particularly when adaptive schemes are employed to modify its radiation patterns. One of its main applications results in considerable increases to the spectral efficiency of present and next generation mobile systems. The other major application is headed towards position location systems, since some of the known techniques comprise angle-of-arrival estimation using antennae arrays. Under such possibilities, mobile radio propagation channel variations studies grow in relevance, specially regarding the antennae arrays main domain of action: the spatial domain. The present work tries to contribute to the overstated context, experimentally investigating the actual mobile radio channel over the temporal (delays) and spatial (angles of arrival) domains. Regionally speaking, similar contributions based on simulations are already found, but none based on measurements. In special, 1.8 GHz indoor soundings have been carried out. Two different temporal spatial sounding techniques have been deployed, based on na available wideband channel sounder successfully assembled and tested as the major contribution of a MSc. dissertation recently presented by a member of the same research team to which this thesis belongs. One of such techniques sinthesyzes the array carrying the sounding out with a single antenna, which is successively moved to occupy the spots corresponding to the array elements. The other method employs an actual array. For both cases, the simplest array configuration has been used: the uniform linear one. Space-time spectra were not directly available in real time during the soundings. Its estimates have been processed later, applying techniques such as the correlogram over the delay domain, and four distinct methods over the spatial domain, the main focus of the present work. Two conventional methods have been used, as well as two parametric ones, potentially capable to increase the estimates resolution, assuming reasonable hypotheses regarding the expected responses. With the estimated spectral responses in hands, comparisons with theoretical estimates allowed a performance assessment of the employed methods. In addition to the spatial channel experimental investigation, the wavelets theory potential of application to the mobile-radio channel study has been checked out. Notably, one of the wavelets theory major applications has been tested as a post-processing technique to improve delay-domain spectral responses. Wavelet decomposition based de-noising has been applied to a huge measurements ensemble, available as the product of previous works of the research group to which this thesis is attached, leading to remarkable results.