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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Theory, design and implementation of a digital receiver for the Advanced Communications Technology Satellite (ACTS) beacons

Sylvester, William R. 18 August 2009 (has links)
This document describes the theory, design and implementation of a digital receiver designed for the ACTS propagation experiments. The Virginia Tech Satellite Communications Group is designing, constructing and distributing eight ACTS propagation terminals (APTs) under a contract with NASA. The terminals will measure the received signal power from the ACTS satellite beacons (20 GHz, 27.5 GHz) in various climates at different elevation angles. The resulting signal power measurement, radiometer and weather measurement data will be used to characterize atmospheric effects on signal propagation at Ka band. Each APT system will contain two identical, independent digital receivers; one 20 GHz channel and one 27.5 GHz channel. The algorithm implemented on each receiver utilizes the results of multiple fast Fourier transforms to reliably identify the carrier tone amidst neighboring modulation tones. The acquisition procedure, can reliably identify the carrier signal at signal-to-noise ratios down to 10 dB in a 20 Hz bandwidth (23 dBHz in a 1 Hz bandwidth, -26 dB relative to clear air conditions on the APT system) in 2 seconds. The receiver then uses a comb filter, two FIR filters and additional FFTs to produce power measurements accurate to 0.1 dB at signal-to-noise ratios down to 5 dB in a 20 Hz bandwidth (18 dBHz in a 1 Hz bandwidth, -31 dB relative to clear air conditions on the APT system) at 1 Hz and 20 Hz sampling rates. The algorithm also provides several supplemental functions including a software selectable detection bandwidth from 2 Hz to 50 Hz (1 Hz increments), spectrum analyzer type output for a 303.333 kHz bandwidth centered on the current carrier frequency and carrier frequency estimates accurate to ±O. 5 Hz. / Master of Science
22

Etude des mécanismes de reconnaissance du transcrit dans la terminaison de la transcription Rho-dépendante / Study of transcript recognition mechanisms in Rho-dependent termination of transcription

Nadiras, Cédric 07 December 2018 (has links)
Terminaison de la transcription. Rho se fixe aux transcrits naissants au niveau d’un site Rut (Rhoutilization) libre à partir duquel il transloque le long de l’ARN (5’→3’) de façon ATP-dépendante pour rattraper le complexe d’élongation de la transcription et induire la dissociation de celui-ci. Il est généralement admis que les sites de fixation de Rho présentent une richesse en Cytosines et une pauvreté en Guanines, ainsi qu’une relative pauvreté en structures secondaires. Les études génomiques ou transcriptomiques n’ont pas dégagé d’éléments consensus ou de règles permettant de prédire les sites de terminaison Rho-dépendants. En combinant approches biochimiques et bioinformatiques, j’ai tenté de comprendre les mécanismes par lesquels Rho reconnait les transcrits.J’ai identifié un ensemble de déterminants de séquence qui, pris ensemble, possèdent un bon pouvoir prédictif et que j’ai utilisé pour construire le premier modèle computationnel capable de prédire la terminaison Rho-dépendante à l’échelle des génomes d’E. coli et Salmonella. J’ai caractérisé in vitro certains de ces terminateurs, en particulier dans les régions 5’UTR, avec l’espoir qu’ils soient impliqués dans des mécanismes de régulation conditionnelle. J’ai identifié des candidats dont l’activité pourrait être sous le contrôle de facteurs comme des petits ARN non codants (sRNA) ou latempérature. J’ai également développé une méthode fluorogénique pour détecter facilement la terminaison Rho-dépendante in vitro et ai commencé à adapter l’approche CLIP-seq à l’étude du transcriptome Rho-dépendant chez Salmonella. Collectivement, mes travaux offrent de nouveaux outils d’analyse et de prédiction de la terminaison Rho-dépendante, une meilleure cartographie des sites d’action de Rho chez E. coli et Salmonella, ainsi que de nouvelles pistes d’étude du rôle de Rhodans l’expression conditionnelle du génome. / Transcripts at a free Rut (Rho-utilization) site from which Rho moves along the RNA in an ATP dependentfashion to catch up with and dissociate the transcription elongation complex. It is generally believed that the Rut sites are, respectively, rich and poor in Cytosines and Guanines as well as relatively poor in secondary structures. Studies at the genomic or transcriptomic scale have notrevealed any stronger consensus features or rules for predicting potential Rho-dependent termination sites. By combining biochemical and bioinformatics approaches, I have explored the mechanisms by which Rho recognizes transcripts to induce transcription termination. I have identified a complex set of sequence determinants which, taken together, have good predictive power and which I used to build the first computational model able to predict Rho-dependent termination at the scale of Escherichiacoli and Salmonella genomes. I have characterized in vitro some of these terminators, particularly in 5'UTRs, with the hope that they will be involved in conditional regulatory mechanisms. I have identified several candidates whose activity may be under the control of factors such as small non-coding RNAs(sRNA) or temperature. I have also developed a fluorogenic method to easily detect Rho-dependent termination in vitro and have begun to adapt the CLIP-seq approach to the study of the Rhodependent transcriptome in Salmonella. Collectively, my work offers new tools for the analysis and prediction of Rho-dependent termination, a better mapping of the sites of probable Rho action in E.coli and Salmonella, as well as several lines of investigation of the role of Rho in the conditional expression of bacterial genomes.
23

Smart Adaptive Beaconing Schemes for VANET

Unknown Date (has links)
Vehicular Ad hoc Networks (VANET) is a wireless ad-hoc network that includes two types of communications, Vehicle-to-Vehicle (V2V) and Vehicle-to-Infrastructure (V2I). In VANET there are two types of messages. The first type is the event-driven messages that are only triggered in case of emergency. The second type is the periodical messages named beacons that are exchanged frequently between vehicles. A beacon message contains basic information about the sending vehicle such as id, location and velocity. Beacons are frequently exchanged to increase the cooperative awareness between vehicles. Increasing beacon frequency helps increasing neighborhood awareness and improving information accuracy. However, this causes more congestion in the network, specially when the number of vehicles increases. On the other hand, reducing beacon frequency alleviates network congestion, but results in out-dated information. In this dissertation, we address the aforementioned challenges and propose a number of smart beaconing protocols and evaluate their performance in di↵erent environments and network densities. The four adaptive beaconing protocols are designed to increase the cooperative awareness and information freshness, while alleviating the network congestion. All the proposed protocols take into account the most important aspects, which are critical to beaconing rate adaptation. These aspects include channel status, traffic conditions and link quality. The proposed protocols employ fuzzy logic-based techniques to determine the congestion rank, which is used to adjust beacon frequency. The first protocol considers signal to interference-noise ratio (SINR), number of neighboring nodes and mobility to determine the congestion rank and adjust the beacon rate accordingly. This protocol works well in sparse conditions and highway environments. The second protocol works well in sparse conditions and urban environments. It uses channel busy time (CBT), mobility and packet delivery ratio (PDR) to determine the congestion rank and adjust the beacon rate. The third protocol utilizes CBT, SINR, PDR, number of neighbors and mobility as inputs for the fuzzy logic system to determine the congestion rank and adjust the beacon rate. This protocol works well in dense conditions in both highway and urban environments. Through extensive simulation experiments, we established that certain input parameters are more e↵ective in beacon rate adaptation for certain environments and conditions. Based on this, we propose a high awareness and channel efficient scheme that adapts to di↵erent environments and conditions. First, the protocol estimates the network density using adaptive threshold function. Then, it looks at the spatial distribution of nodes using the quadrat method to determine whether the environment is highway or urban. Based on the density conditions and nodes distribution, the protocol utilizes the appropriate fuzzy input parameters to adapt the beaconing rate. In addition, the protocol optimizes the performance by adapting the transmission power based on network density and nodes distribution. Finally, an investigation of the impact of adaptive beaconing on broadcasting is conducted. The simulation results confirm that our adaptive beaconing scheme can improve performance of the broadcast protocols in terms of reachability and bandwidth consumption when compared to a fixed rate scheme. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2018. / FAU Electronic Theses and Dissertations Collection
24

Novel spectroscopic probes of sunscreens, initial excited-state structural dynamics and DNA photodamage

Oladepo, Sulayman 06 1900 (has links)
This thesis discusses developing new tools to probe DNA damage resulting from photoinduced chemical processes and probing the initial excited-state structural dynamics of nucleic acids and sunscreen agents. The results of this thesis show that UV resonance Raman spectroscopy (UVRRS) is an information-rich probe of chemical compositions in in situ analysis of sunscreen formulations. The results indicate that 244-nm excited UV resonance Raman spectra can provide a limit of detection of 0.23% w/w of sunscreen active ingredients (AIs), far below typical active ingredient (AI) concentrations in sunscreen formulations. UVRRS was used to probe the photostability of sunscreens, by determining the initial excited-state structural dynamics of Benzophenone-3 (BZ3), a common sunscreen active ingredient. Only minor excited-state structural distortions were obtained, based on the low displacement values, suggesting an inherently stable molecule. The largest structural change occurs along the carbonyl stretch, suggesting a strong interaction with the methanol solvent and a dissipative decay path for the molecule. Similarly, to gain an insight into how the structure of nucleic acids determine their photochemistry, UVRRS was used to probe the initial excited-state structural dynamics of 9-methyladenine (9-MeA). As for BZ3, the initial excited-state structural dynamics obtained for 9-MeA, are low, and much lower than for pyrimidine bases, providing a strong evidence for the photochemical stability of this purine base analog, compared to pyrimidines. Since DNA does not exist in isolation in cells, the role of a UV-absorbing amino acid, tryptophan, in UV-induced DNA photodamage was explored using molecular beacons (MBs) to detect the damage. The results indicate that tryptophan protective effects on DNA far outweighs their photodamage potential. However, MBs are expensive and they have some technical limitations, despite their exquisite sensitivity. Therefore, a new DNA damage detection method was developed based on smart probes (SPs). These probes are shown to be sensitive and sequence specific for detecting DNA photodamage.
25

Development of a method for correlating integrin beta 1 expression and surface characteristics under individual cells

Myers, Meredith A. 12 August 2011 (has links)
Osseointegration, or the direct integration of an implant into bone tissue, is necessary for implant success. Titanium is commonly used clinically in dental and orthopaedic implants because of its passivating oxide layer, which facilitates osseointegration, and its mechanical properties such as a modulus of elasticity similar to bone. Diverse studies have shown that surface microtopography, chemistry, and surface energy affect osteoblast behavior. The problem with these studies is that they access the average behavior of a culture in response to a substrate and not the behavior of individual cells. The objective of this study was to develop a method for correlating the behavior of individual cells with the characteristics of the surface underneath them. More specifically, this work developed a method to correlate integrin beta-1 (β1) expression with the surface characteristics under individual cells. Integrins are cell surface receptors that bind to specific proteins in the extracellular matrix adsorbed on the implant surface. Previous work has shown that expression of certain integrins is increased when osteoblasts on titanium substrates develop a more differentiated phenotype, and that integrin β1 is necessary for osteoblast response to roughness on titanium substrates. This study used molecular beacons specific to integrin β1 to quantify integrin β1 expression of MG63 cells cultured on titanium disks. A template was designed to coordinate the location of cells using fluorescence microscopy and scanning electron microscopy (SEM) in reference to laser etchings on the disks. After live cell imaging, cells were fixed, dried, and critical point dried for focused ion beam (FIB) milling. Transmission electron microscopy (TEM) sections of cells identified with high and low integrin β1 molecular beacon intensity were milled, and cells with high and low integrin β1 molecular beacon intensity were also serial sectioned. While our TEM results were inconclusive, SEM images from serial sectioning showed contact points between the cell body and the substrate, consistent with previous results. Cells cultured on pretreatment (PT) or sandblasted acid etched (SLA) titanium surfaces were also serial sectioned, showing that cells on SLA surfaces have more regions of contact between the cells and the substrate than cells on PT surfaces. This work is significant as it is the first study to develop a method to correlate individual cell behavior with the substrate surface characteristics under the individual cells. Previous studies have reported the average cell behavior in response to their substrates, while this work allows for the study of substrate surface characteristics that positively affect integrin β1 expression in individual cells. Further optimization of the fluorescence imaging process and FIB milling process could be done, and the method developed in this study could be used in future studies to investigate surface characteristics after using other fluorescent analyses of cell behavior, such as immunocytochemistry.
26

Novel spectroscopic probes of sunscreens, initial excited-state structural dynamics and DNA photodamage

Oladepo, Sulayman Unknown Date
No description available.
27

Development of androgen receptor messenger RNA targeted molecular beacons for use in the study of prostate cancer progression

Glick, Cindy Jennifer 31 July 2008 (has links)
Messenger RNA (mRNA) posttranscriptional regulation has been implicated in the development and/or progression of several diseases including many types of cancer, rheumatoid arthritis, vascular disease, and Alzheimer's disease. Differential regulation of Androgen Receptor (AR) mRNA has been associated specifically with prostate cancer progression. In this thesis, molecular beacons were developed to allow for the detection of the expression and localization of AR mRNA in live prostate cancer cells. These beacons were then applied as a tool for studying how AR mRNA regulation is involved in prostate cancer growth and advancement. Two AR mRNA targeted beacons were designed and tested in solution and in live cells to determine their functionality. The beacon-based approach for AR mRNA detection was then optimized through the use of the two beacons in tandem and alteration of their backbone chemistry. A series of validation tests were performed on these beacons, including testing their abilities to: 1) produce a feasible localization pattern, 2) discriminate between AR positive (AR+) and AR negative (AR-) prostate cancer cell lines and 3) follow stimulus-induced changes in AR mRNA expression. Based on these results, a dual chimeric beacon approach was selected to determine the role of AR mRNA regulation in two systems that represent important stages in prostate cancer growth and progression: 1) hormone stimulation of androgen-dependent prostate cancer cells and 2) progression of androgen-dependent prostate cancer cells to the androgen-independent state. Our results suggest that changes in AR mRNA expression, organization, and localization may be indicative of molecular mechanisms involved in these critical transitions associated with prostate cancer progression. Taken together, this work provides a feasibility study for visualizing changes in AR mRNA state as a diagnostic measure for evaluating the aggressiveness of the disease and demonstrates the possible utility of therapeutically targeting AR mRNA regulation in order to prevent prostate cancer advancement.
28

Aspects of dedicated (dormant) chip for intelligent part handling by industrial robots

Theron, Stephanus Andreas 12 September 2012 (has links)
M.Ing. / Intelligent object identification (the ability to find the identity, position and orientation of an remote object) in a Manufacturing environment plays an important role in the areas of Automation and Manufacturing. Radio frequency identification (RFID) systems have solve the problem of finding the identity of a remote object, but it fails to determine the position and orientation. The Global Positioning System (GPS) have a solution to find the position of a remote object in the global environment, but in a Manufacturing environment it fails. The main obstacle to overcome in finding a unique solution with radio frequency technology is reflections. This thesis investigates the idea of finding the identity, position (and orientation) of a (dormant) chip remotely. The chip transmits a binary signal at 244kHz. The string is Amplitude modulated. The receiver demodulates the signal to obtain the chip's identity. The receiver antenna is divided into four quadrants. First the quadrant in which the chip is located are determined. Three different voltages are then measured to obtain the position of the chip in the specific quadrant. Reflections can be ignored since the system works at a low frequency.
29

Exploring the Materiality of the Web of Things : A study about web technology as design material for ubiquitous computing

Wiemann, Meike January 2015 (has links)
When looking at the Internet of Things the question arises how people, places and things will be connected to each other in the future. One option to create interoperability between devices and humans for the Internet of Things is to use open web standards. Researchers have named this approach the Web of Things and have studied the vision by showing the technical feasibility and by suggesting software architectures. What has been missing so far is a designer’s view on the challenges of connecting the virtual and the physical world with web technology. This thesis therefore aims to explore how current web technologies can be used as design material for the Web of Things. The results indicate that new web technologies like push notifications work well in the context of ubiquitous computing. Additionally, the repertory grid method was applied to evaluate how users experience the Web of Things. It was found that the prototypes were perceived as easy to use, personal and working instantly but the participants were also clearly aware of the dependency to a working smartphone.
30

Implementace nástroje pro analýzu dat o pohybu osob / Implementation of a tool for human movement data analysis

Matějka, Martin January 2014 (has links)
The aim of this thesis is to provide an insight into theoretical and practical aspects of an analytical tool developed by Ondřej Funiok, Vilém Kalus, Tomáš Rosenberger and Martin Matějka at the University of Economics in Prague. The goal was to develop a tool which could be used for an analysis of human movement within a given place (e.g. retail store) and which could leverage traditional customers' data like age, gender or profession in order to enrich outcomes of conducted analysis, as well as provide a new segmentation of these customers based on their movement. Given that, one of the possible scenarios is that marketers would be able to finely-target their campaigns and use the space more effectively. The thesis contains a short introduction to Location Intelligence as a category of systems which the developed tool belongs to. Further a research of existing theses, articles etc., as well as already available products is conducted. Since a documentation of web services' application interface has proved to be an important aspect of the development, a research and comparison of supporting tools follows. Fourth and fifth chapters are of rather practical nature -- the first of them is about an overall design and architecture of the developed tool, while the second one describes the used application interface and its documentation in detail together with the most important aspects of a backend component -- so called ,,GA-Server``.

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