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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.
161

FUNDAMENTAL PROPERTIES, ACTIVITY, AND PLANET-HOSTING POTENTIAL OF YOUNG SUNS NEAR EARTH

Cabrera Salazar, Nicole E. 10 May 2017 (has links)
In this dissertation, we conduct a census and assessment of the nearest young Sun-like stars and investigate the potential for finding giant planets orbiting spotted stars using the radial velocity (RV) method at optical and near-infrared wavelengths. Based in part on new spectroscopic measurements conducted here, we have assembled a complete list of 129 young (<150 >Myr), nearby Sun-like stars and their fundamental parameters, including rotational and multiplicity information. We also provide a statistical analysis of their stellar parameters, including projected rotational velocity and inclination. Sixteen of these stars have no close companions and have low projected rotational velocities (vsini/s) that are ideal for precision RV planet searches. Seven of these rotate nearly edge-on and are ideal targets for upcoming transiting planet searches, assuming low obliquity. We conduct precision RV planet search of 7 young Sun-like stars using the TRES spectrograph, mounted on the 1.5-m Tillinghast Reflector at the Fred L. Whipple Observatory, and with the SOPHIE spectrograph, mounted on the 1.93-m Telescope at the Observatoire de Haute Provence; we achieve a precision of 10 m/s for both. Four stars are identified as having larger RV variations that are periodic, possibly caused by an orbiting companion. However, the RV variations are correlated with asymmetries in the spectral absorption features, which instead suggests that the variations are caused by spots. Nevertheless our observations provide new independent measures of the rotation periods of these stars. Through this analysis we tentatively confirm the planetary companion around BD+20 1790 in the presence of activity. We additionally investigate the use of comparing red orders of the optical spectrum to the blue orders in order to distinguish spots from planets; we find that this method can be effective for observations that span the full wavelength range of the optical. We also investigate our detection limits at optical wavelengths and find that we are sensitive to over 90% of short period giant planets. Next, we assemble the stellar jitter measurements of our stars with previous studies of all Sun-like stars younger than 1 Gyr to investigate how stellar jitter declines with stellar age. We find that stellar jitter decreases with stellar age as t^(0.53±0.13), similar to the relationship between stellar rotation period and stellar age. The implication is that it will be diffcult to find planets orbiting stars younger than 100 Myr without using techniques that mitigate star spot noise. Furthermore, we present a near-infrared RV search for giant planets orbiting 8 stars observed with CSHELL at the NASA Infrared Telescope Facility (IRTF). Because of the limited wavelength coverage (29 ̊A) and older (1980s) detector technology, the achieved precision of 200 m/s inhibits finding the majority of exoplanets, but is nevertheless sufficient to identify short-period brown dwarfs for these stars. We also analyze our detection limits at IR wavelengths and find that we are only sensitive to roughly 50% of short period giant planets. Finally, we present a new orbital solution for V835 Her, a spectroscopic binary with a 3 day orbital period.
162

Variability in cortical haemodynamic response during executive function tasks in older adults using functional near infrared spectroscopy

Halliday, Drew 18 August 2016 (has links)
Variability in neural activity has historically been treated as noise, in favour of deriving estimates based on central tendency (e.g., mean). Recently, researchers have shown that variability and mean confer different sources of information and that increased variability in neural activity is associated with superior behavioural performance and that it decreases during late-life. Although mounting evidence suggests that neural variability is beneficial, it is less clear whether these findings are driven by within- or between-person factors and whether they are apparent during higher-order cognitive tasks. Further, variability can be derived in several different ways, drawing into question its congruence across operationalizations. The present investigation sought to separate within- and between-person sources of variance in order to ascertain what was driving any observable effects in three operationalizations of cerebral oxygenation, computed based on central tendency (mean), variability (standard deviation) and signal complexity (multivariate multiscale entropy). 25 older adults (71-81 years of age) completed two tasks of executive functions while undergoing assessment using functional near infrared spectroscopy. Time-varying covariation models were employed to estimate the effects of cerebral oxygenation on behavioural performance, as well as the moderating effects of age and fall status. Findings suggest that mean and variability are differentially associated with behavioural performance and are increased in older adults at greater fall risk. Whereas mean based computations were positively associated with more accurate and faster responding, variability based computations were primarily associated with faster responding only and occurred in non-overlapping regions of prefrontal cortex. Future studies of neural variability may consider examining within- and between-person factors and operationalizing signal complexity in cerebral oxygenation over longer time periods to examine its effects over multiple time scales. / Graduate / drewh@uvic.ca
163

Synthesis and characterization of colloidal lead chalcogenide quantum dots and progress towards single photons on-demand

Abel, Keith Alexander 19 August 2011 (has links)
Nanometer-sized semiconductor crystals, termed ‘quantum dots’, are of fundamental interest because of their size-tunable properties. Three-dimensional quantum confinement of charge carriers by the small crystal size results in discrete atomic-like electronic states. This dissertation describes the synthesis and in-depth characterization of lead chalcogenide colloidal quantum dots for forthcoming applications as near-infrared single photon emitters. An efficient single photon source that operates at telecommunication wavelengths (between 1.3 and 1.6 µm) is a basic requirement for many photonic quantum technologies, such as quantum computing and quantum cryptography. Chapters 1 and 2 of this work provide an introduction to colloidal quantum dots and their use as single photon emitters. It includes a description of photonic crystal microcavities and their ability to enhance the spontaneous emission rate of quantum dots. The synthesis and basic characterization of PbSe and PbS quantum dots is then discussed in chapter 3. In particular, a new synthetic method for the preparation of highly photoluminescent PbS quantum dots is presented. PbSe/CdSe core/shell quantum dots prepared by a cation exchange reaction are also described and a significant improvement in photo-stability is shown. Chapter 3 concludes with a description of three different surface modification techniques. PbSe core and PbSe/CdSe core/shell materials are investigated further in chapter 4 by advanced characterization techniques that include high-angle annular dark field (HAADF) imaging, energy-filtered transmission electron microscopy (EF-TEM) imaging, energy-dependent X-ray photo-electron spectroscopy (XPS), small angle X-ray scattering (SAXS), and small angle neutron scattering (SANS). The information obtained from these techniques is combined to form a structural model of the PbSe core and PbSe/CdSe core/shell quantum dots with greater complexity than previously reported. In chapter 5, the temperature-dependent photoluminescence from PbSe and PbSe/CdSe core/shell quantum dots is discussed and a thermal model is presented that accounts for the large (non-trivial) temperature dependence of the Stokes shift and photoluminescence lineshape over the entire temperature range (4.5 to 295 K). Chapter 6 examines two scalable methods to integrate the colloidal quantum dots into silicon two-dimensional photonic crystal slab microcavities (a requirement for efficient single photon emission). Finally, conclusions and possible future work are discussed in chapter 7. / Graduate
164

Delivery of Myoglobin Polymersomes Results in Tumor Hemorrhagic Necrosis and Enhanced Radiation Response

Hofmann, Christina Lehmkuhl January 2015 (has links)
<p>There is a critical need to target tumor hypoxia as patients with hypoxic tumors have worse prognosis due to aggressive phenotypes and resistance to radiotherapy and chemotherapy. The overall goal of this work is to improve response to conventional cancer therapies by targeting tumor hypoxia. This has been carried out and evaluated through the use of polymersome-encapsulated myoglobin (PEMs) with the hypothesis that O2-releasing PEMs will increase tumor oxygenation, and thereby improve response to radiotherapy. Mb was chosen as an O2 carrying protein to deliver to tumors because it has a strong association to O2, providing a mechanism to deliver O2 only within the hypoxic regions of the tumor. Mb was loaded within nanoscale polymeric vesicles that were expected to accumulate within solid tumors due to the enhanced permeability and retention (EPR) effect. This hypothesis has been tested through the following aims:</p><p>1. Develop NIR imaging techniques for studying the biodistribution and pharmacokinetics of polymersomes</p><p>2. Establish the effects of Mb-containing polymersomes on tumor physiology</p><p>3. Modify tumor growth through delivery of Mb polymersomes in combination with a cytotoxic therapy specific to aerobic tumors</p><p>These aims have been evaluated through numerous in vivo studies. First, polymersomes of various polymer formulations and diameters ranging from 110-550 nm were prepared with a near-infrared (NIR) -emissive fluorophore. Using live animal fluorescence imaging, I was able to study the biodistribution of the polymersomes following i.v. administration, demonstrating significant polymersome accumulation in orthotopic 4T1 mammary carcinomas. In addition, a novel method for measuring pharmacokinetics was developed, using serial small volume blood draws from individual mice. The plasma fluorescence in microcapillary tubes was used to quantify polymersome concentrations, demonstrating long circulation half-lives that varied from 6-23 h. Toxicity of various polymersome formulations were also studied in vitro and in vivo, revealing negligible toxicities.</p><p>For the second aim, PEMs were administered i.v. in tumor-bearing mice. Unexpectedly, we observed a dramatic gross tumor effect within hours of treatment in both orthotopic 4T1 tumors and flank Renca renal cell carcinomas. Histological analysis revealed endothelial cell apoptosis as early as 1 h following treatment, with scattered tumor cell death throughout the tumor by 4 h. Hematoxylin and eosin staining showed significant necrosis 24 h following PEM treatment. Vascular effects and polymersome distribution were studied in 4T1 window chamber tumors. Following i.v. treatment with PEMs, intravital microscopy was used to image polymersome fluorescence, brightfield transmission was imaged for vessel morphology and blood flow, and a tunable filter was used for determining hemoglobin (Hb) oxygen saturation. Tumor hemorrhaging was observed within hours of PEM treatment, which was not seen with empty polymersomes. This was consistent with the gross tumor effects observed initially. Hb saturation decreased in both the PEM and empty polymersome groups, but not in saline-treated mice. While we expected to observe an increase in tumor oxygenation by using Mb as an oxygen carrier, we actually observed hemorrhage, decreased oxygenation, and central tumor necrosis. In vitro studies using human endothelial cells demonstrated dramatic changes in cell morphology and increased permeability due to Mb and PEM treatments, which appear to be enhanced in an oxidative environment. These in vitro and in vivo observations are similar to what is seen with tumor vascular disrupting agents.</p><p>For the third aim, I combined radiotherapy (RT) and PEM treatment with a new hypothesis. I originally expected the PEMs to increase tumor oxygenation, thus making the tumor more susceptible to RT. However, considering the results from the second aim, this hypothesis was modified: the PEMs would result in necrosis of the tumor core, while RT would target the more oxygenated rim of the tumor, thus leading to improved tumor growth delay compared with PEM or RT alone. This hypothesis was tested in both orthotopic, syngeneic 4T1 tumors as well as flank FaDu xenografts. 4T1 tumor cells were surgically implanted within the dorsal mammary fat pad of mice and grown until ~200 mm3. A CT microirradiator with a square collimator was used in order to locate and specifically irradiate the tumor. Within 1 h following RT, the PEMs were administered i.v.. Mice receiving PEMs with no RT showed a significant decrease in tumor growth compared with saline-treated mice (p = 0.0001 for time to 3x original tumor volume). In addition, the combination of RT plus PEMs reduced tumor growth compared with RT alone (p = 0.0144 for time to 3x original tumor volume). However, this effect was not seen with FaDu tumors. This may have been due to excessive radiation dose or other compounding factors: the timing between RT and PEM treatment was not optimized, and the number of mice per group was small (3-4). </p><p>Thus, the conclusions for each aim are as follows:</p><p>1. Develop NIR imaging techniques for studying the biodistribution and pharmacokinetics of polymersomes</p><p>NIR imaging techniques were optimized for studying polymersomes, demonstrating long plasma circulation times and accumulation within tumors.</p><p>2. Establish the effects of Mb-containing polymersomes on tumor physiology</p><p>While the hypothesis was that PEMs would accumulate within hypoxic tumors and subsequently increase O2 tension, we observed a rapid decrease in tumor oxygenation followed by a dramatic hemorrhagic effect of Mb polymersomes, which appear to be due to both endothelial cell apoptosis and morphological changes, resulting in central tumor necrosis.</p><p>3. Modify tumor growth through delivery of Mb polymersomes in combination with a cytotoxic therapy specific to aerobic tumors</p><p>Combination therapy of PEMs with RT results in enhanced tumor growth delay in aggressive 4T1 mammary carcinomas compared with RT or PEMs alone.</p><p>These studies have led to a proposed mechanism for the PEM anti-tumor effect in combination with RT. Prior to PEM administration, RT is administered, resulting in tumor cell kill of the well-oxygenated tumor periphery. Mb polymersomes are then injected i.v. and begin to accumulate within tumors due to the EPR effect. As shown in Aim 1, this accumulation occurs over a short time scale. Within 30 min of PEM treatment, the Mb is believed to act on tumor vessels, resulting in morphological changes and apoptosis of endothelial cells. These effects are expected to increase permeability of the vessels and expose the basement membrane, which leads to clotting and decreased blood flow. Both decreased perfusion and increased permeability are believed to have a catastrophic effect on interior tumor vessels. Hemorrhage results as the endothelial cells die, resulting in tumor core necrosis. Therefore, the result is tumor cell kill at the periphery due to RT and central tumor necrosis due to PEM treatment.</p><p>PEMs have potential in cancer therapy as a new class of VDAs. While the mechanism requires further investigation, this work has demonstrated that PEM treatment results in tumor vessel destruction and central necrosis. PEMs accumulate within tumors, thus minimizing the systemic toxicity of treatment commonly seen with VDAs. By combining PEMs with a therapy that kills the better perfused tumor periphery, PEMs show promise in improving tumor response. Future mechanistic studies will be needed in order to maximize vessel damage and optimize combination dosing schedules to improve outcome.</p> / Dissertation
165

Dosage du polyisoprène et des résines de la biomasse de guayule (Parthenium argentatum) par spectroscopie proche infrarouge (SPIR) : méthodes d'extraction par solvant de référence / Quick analysis of rubber,lipids and other components of the biomass of Parthenium argentatum by NIRS and fractionating process.

Suchat, Sunisa 09 November 2012 (has links)
Dosage du polyisoprène et des résines de la biomasse de guayule (Parthenium argentatum) par spectroscopie proche infrarouge (SPIR) Méthodes d'extraction par solvant de référence Un protocole basé sur l'extraction accélérée (ASE) avec l'acétone (EA) (résine) puis l'hexane (EH) (polyisoprène, PI) a été sélectionné et optimisé (rendement maximal; adapté à l'analyse de séries) ; quantification d'abord basée sur le poids de l'extrait (gravimétrie). L'EH est maximal à 120°C après étapes avec l'acétone à 40°C (plan d'expérience). La contamination croisée a été confirmée par SEC et FTIR (5 à 29%), conduisant à une deuxième méthode basée sur résine et PI et non plus sur EA et EH, incluant le PI de faible masse molaire (Mw) de l'EA. Ces 2 méthodes de référence ont servi à calibrer la SPIR (chimiométrie/PLS, coeff. beta) afin de relier signature spectrale, PI, résine. ASE-SPIR, couplés ici pour la première fois, ont été plus performants (R² 0.96; 0.98; RPD 4.8; 4.6; EA et EH resp.) que les méthodes de la littérature, grâce aux 215 échantillons représentatifs (génotypes, saison, âge du guayule, climat). La méthode tenant compte de la contamination est moins performante (erreur exp. due aux analyses SEC et FTIR; variation de composition des résines). Ayant montré la dégradation du PI au cours de l'extraction, un autre protocole a été étudié (biomasse humide, un solvant, une seule étape, 20°C) afin d'accéder au Mw «natif », donnant 2.106 g au lieu de 6.105 avec la biomasse séchée; il faut donc être prudent face aux Mw de guayule de la littérature. Ce travail montre la nécessité de tenir compte de la complexité de la biomasse de guayule (échelle cellulaire/PI vacuolaire, résine des canaux; moléculaire/instabilité chimique) lors de l'extraction du PI pour l'analyse structurale. Ces méthodes analytiques ont contribué à produire des prototypes (gant non allergisant, pneu) à haut Mw et à l'acclimatation en Europe dans le cadre du projet EU-Pearls. / Measurement of resin and polyisoprene in Parthenium argentatum (guayule) biomass using near infrared spectroscopy (NIRS) -Associated solvent-based reference methods .A protocol based on sequential extraction with acetone (resin) and hexane (polyisoprene, PI) with accelerated solvent extraction (ASE) was optimized and selected (maximized yield; adapted to large series) instead of Soxhlet and homogenizer. Quantification was first based on extract weight (gravimetry). Hexane extract was maximized at 120°C, after acetone steps at 40°C, through an experimental design. Cross contamination was confirmed and quantified (5 to 29%; SEC and FTIR). This gave a second method based on resin and PI, instead of crude extracts, accounting for low average molar mass PI (Mw) extracted by acetone instead of hexane. Both reference methods were used for calibrating NIRS applied to powdered biomass, with chemometric tools (PLS loadings, beta coefficients) to interpret spectral bands vs PI-resin relationship. ASE, not used before as reference, is highly reliable, and calibration with gravimetry (R² 0.96; 0.98; RPD 4.8; 4.6; for acetone and hexane extract) better than published data, thanks to the 215 samples covering genotypes, harvest date, plant age, climate. The method using cross contamination was less efficient because of higher experimental error induced by additional SEC and FTIR, and change in resin composition. Having set NIRS methods, a new protocol (single solvent THF, minimized processing, 20°C, fresh biomass) was designed to avoid degradation, yielding PI extracts with Mw above 2.106g/mole, closer to in vivo structure (6.105 when using dried guayule); caution to sample preparation in literature dealing with guayule PI structure. This calls for considering the complex structure of guayule biomass (PI in cells; resin in ducts; chemical instability) when extracting PI. These methods allowed producing high PI Mw glove and tire prototypes and domesticating this new crop in Europe within the EU-Pearls project.
166

Application of two-dimensional correlation spectroscopy for monitoring the mechanism of reaction between phenyl glycidyl ether (PGE) and metaphenylene diamine (mPDA)

Hollock, Michael R. January 1900 (has links)
Master of Science / Department of Chemical Engineering / J.R. Schlup / The curing reaction for the amine epoxy resin system of phenyl glycidyl ether (PGE) with metaphenylene diamine (mPDA) was investigated using two-dimensional correlation spectroscopy in the near-infared region (2DNIR). Synchronous and asynchronous correlation maps were generated using 2Dshige© software. The characteristic NIR band assignments were made, including the identification of new peaks for the O-H combination band in the 4825-4750 cm[superscript]-1 region and the CH stretching vibration overtone at 6018 cm[superscript]-1. Finally, the data suggests the reaction proceeds as follows: the appearance of the OH groups and C-H backbone vibrations occurs before the primary amine reactions and epoxide rings disappear.
167

Monitoramento em linha de reações de copolimerização em emulsão de acetato de vinila e acrilato de butila em um reator contínuo pulsado de pratos perfurados usando espectrocospia NIR. / In-line monitoring of vinyl acetate and butyl acrylate emulsion copolymerization in a continuous pulsed sieve plate reactor using NIR spectroscopy.

Chicoma Lara, Dennis 25 August 2009 (has links)
Neste trabalho estudou-se a viabilidade e sensibilidade do monitoramento em linha, utilizando a espectroscopia NIR, da evolução das concentrações dos monômeros e do polímero, e do tamanho médio das partículas, em processo de copolimerização de acetato de vinila e acrilato de butila em emulsão ao longo das seções de um reator contínuo pulsado de pratos perfurados. Para a elaboração de modelos de calibração NIR destas variáveis foram realizadas reações em um reator tanque agitado de mistura, correlacionando os dados experimentais adquiridos via gravimetria e cromatografia gasosa para a determinação da concentração dos monômeros residuais e a espectroscopia de correlação de fótons para a determinação do tamanho médio das partículas, com os espectros coletados simultaneamente utilizando uma sonda de imersão no modo de transflectância. O modelo de predição NIR foi calibrado utilizando o pacote computacional OPUS próprio do equipamento NIR (FT-NIR IFS 28N) através da ferramenta QUANT baseada em métodos multivariados PLS e PCA. O uso da segunda derivada com 25 pontos de alisamento e da primeira derivada com 17 pontos de alisamento foram escolhidas como melhores pré-tratamentos para as concentrações dos monômeros e o tamanho médio das partículas, respectivamente. A validação dos modelos foi realizada com reações conduzidas no reator continuo pulsado de pratos perfurados inserindo a sonda NIR nas diferentes seções da coluna. Os resultados apresentaram uma concordância satisfatória entre os dados experimentais medidos off line e os resultados preditos pelos modelos de calibração. As predições feitas a partir dos modelos de calibração NIR serviram para a estimativa de outros variáveis importantes no processo de copolimerização, tais como, a conversão global e individual, composição do copolímero e numero de partículas. Estas variáveis estimadas foram também comparadas satisfatoriamente com os valores correspondentes obtidos a partir de dados medidos experimentalmente. Adicionalmente, o monitoramento foi capaz de detectar a ocorrência de alguns distúrbios operacionais, tais como, paradas de alimentação dos reagentes, verificando-se sua sensibilidade de detecção de problemas em tempo real, os resultados reportaram com sucesso os desvios produzidos pela perturbação operacional. Os resultados mostraram que é possível realizar com sucesso o monitoramento em linha, in situ e em tempo real, de diferentes variáveis simultaneamente, no processo de copolimerização em emulsão em um reator continuo com potencial alternativa para uso em ambiente industrial. / This work deals with the study of the viability and sensitivity of the on-line monitoring, using NIR spectroscopy, of monomers and polymer concentration and average particle size during continuous vinyl acetatebutyl acrylate emulsion copolymerization carried out in a novel tubular pulsed sieve plate reactor. For the elaboration of NIR calibration models of these variables, reactions were performed in a stirred tank reactor, and the experimental data of residual monomers concentrations obtained by gravimetry and gas chromatography, and average particle size obtained by photon correlation spectroscopy were correlated with the spectra collected simultaneously in the process using an immersion probe in transflectance mode. The NIR calibration model was obtained by using the built-in computational package OPUS-QUANT in the NIR equipment (FT-NIR IFS 28N) based on PLS and PCA multivariate methods. The use of second derivative with 25- point-smoothing filter and the first derivative with 17-point smoothing filter were chosen as the best pre-treatments for the monomers concentration and the average particle size, respectively. The model validation was tested with reactions carried out in a continuous pulsed sieve plate tubular reactor, in which a NIR probe was inserted into different sections along the column. The results showed a reasonable agreement between experimental data and NIR predicted data. These results were also used to estimate other important variables in the copolymerization, such as the global and individual conversion, the copolymer composition and the number of particles. These estimated variables were also satisfactorily compared with corresponding data estimated from the experimental data. In addition, the NIR monitoring was able to detect some operational disturbances, such as the interruption of reagent feeding, thus showing its sensitivity for successfully detecting process disturbances in real time. The results indicate that NIR spectroscopy is a powerful tool for in-line, in-situ, real-time monitoring of different variables simultaneously during emulsion copolymerization process carried out in a novel continuous reactor, being a potential alternative for use in a real industrial environment.
168

Développement de nouveaux chromophores dipolaires pour l'imagerie de fluorescence et l'imagerie photoacoustique / Design and synthesis of new dipolar chromophores for fluorescence imaging and photoacoustic imaging

Rémond, Maxime 31 October 2018 (has links)
Cette thèse traite de la conception, la synthèse et la caractérisation de chromophores dipolaires D-π-A pour l’imagerie de fluorescence et l’imagerie photoacoustique.La première partie est consacrée à la synthèse et à l’étude de nouveaux fluorophores émettant à l’état solide dans le proche infrarouge, pour l’imagerie de fluorescence biphotonique. Afin d’améliorer les propriétés optiques à l’état solide, nous avons exploré différentes pistes en modifiant d’abord le groupement D donneur d’électron, puis le groupement A accepteur et enfin le pont π conjugué de nos structures dipolaires.La seconde partie concerne l’imagerie photoacoustique. Cette imagerie, basée sur une excitation optique et une détection acoustique, nécessite une forte absorption dans le proche infrarouge. Une des stratégies pour effectuer ce décalage bathochrome de l’absorption a été incorporation de groupements thiophènes à faible aromaticité, afin d’augmenter la délocalisation du système π. Parallèlement, nous avons aussi étudiés des hémicyanines, présentant de fortes absorptions au-delà de 650 nm.Enfin, les colorants ont été formulés en nanoparticules organiques afin d’acquérir une solubilité aqueuse pour leur application en imagerie. Deux types de nanoparticules ont été étudiés : la nanoprécipitation des colorants en présence d’un agent tensioactif, ainsi que l’encapsulation des colorants dans une matrice polymérique amphiphile stabilisée par une couche de silice. Les meilleurs chromophores ont permis l’acquisition d’images de cellules par microscopie biphotonique ainsi que d’images photoacoustiques de circuits microfluidiques et de la microvascularisation de souris in vivo. / This thesis is focused on the conception, synthesis and characterization of dipolar dyes D-π-A for fluorescence imaging and photoacoustic imaging.The first part aim to synthesize and to study new fluorophores emitting in the solid-state in the near-infrared for fluorescence imaging with two-photon excitation. In order to improve the optical properties in the solid-state, we first explored various electron donating groups D, then acceptors A and finally we modified the π bridge. In a second part, we focused on dyes for photoacoustic imaging. This technique is based on an optical excitation and an acoustic detection. It requires a strong absorption in the biological window. To red shift the absorption we incorporated a thiophene bridge with low aromaticity to increase the delocalization. We also studied several hemicyanines with strong absorption above 650 nm.Finally, dyes were formulated as water-soluble nanoparticles for their final application for imaging. Two types of nanoparticles were studied: nanoprecipitated dyes stabilized by a surfactant to increase the colloidal stability or encapsulated dyes in a amphiphilic polymer matrix stabilized with a silica shell. Those nanoparticles enabled cells imaging with biphotonic florescence imaging as well as photoacoustic imaging of a microfluidic chip and of the microvascularisation of mice ears in vivo.
169

Enabling awareness in nursing homes with mobile health technologies

Klakegg, S. (Simon) 22 February 2019 (has links)
Abstract This thesis explores the use of assistive in-situ technologies for formal caregivers in nursing homes. More specifically, focus is placed on improving context awareness and medication management. Although these topics have previously been researched for elderly care in general, few solutions targeting nursing homes have been generated. As the aging population further increases the burden on this care environment, it is important that solutions are found to help maintain care quality. The main findings in this thesis emphasise how technology can assist formal caregivers and facilitate increased patient wellbeing. The articles presented in this thesis describe our creation of a context-aware sensor system (named CARE) and a non-expert miniaturised near-infrared spectroscopy (MNIRS) solution. Both systems were designed iteratively with the help of nurses and were evaluated in a nursing home. CARE quantifies elderly residents’ behaviour, analyses the resulting data and produces valuable and actionable insights for nurses. Results from a two-month-long user study demonstrate that the system can facilitate increased awareness of patients’ needs and enhance care service. The custom MNIRS solution allows nurses to scan pharmaceuticals and obtain accurate identifications. This method significantly outperforms currently available tools in nursing homes and represents a promising solution that can reduce medication mismanagement. In the discussion section of the thesis, we revisit the research questions defined in the introduction and examine how each were answered. In addition, we discuss the augmentation of nursing home technology and various stakeholders’ perspectives. We then highlight how the work covered in this thesis was conducted in collaboration with industry and offer some conclusions, limitations and reflections. / Tiivistelmä Tämä väitöstyö tutkii paikkasidonnaisten teknologioiden käyttöä hoitajien työn helpottamiseksi vanhusten palvelukodeissa. Työn keskiössä on erityisesti kontekstitietoisuuden lisääminen ja lääkehoidon valvonta. Näitä aiheita on tutkittu laajalti aiemminkin, mutta aitoihin ympäristöihin keskittyviä ratkaisuja on vielä vain vähän. Väestön ikääntyminen aiheuttaa haasteita vanhustenhoidossa, ja siksi on tärkeää kehittää ratkaisuja hoidon laadun ylläpitoa varten. Väitöstyön löydökset painottavat teknologian roolia hoitajien avustajana sekä hoidettavien hyvinvoinnin ylläpitäjänä. Työn artikkelit kuvailevat kontekstitietoisen järjestelmän (CARE) koko kehitys- ja elinkaaren sekä lähi-infrapunaspektroskopiaan perustuvan ratkaisun lääkehoidon prosessien parantamiseksi. Molemmat järjestelmät kehitettiin iteratiivisesti hoitajien avulla ja koestettiin aidossa ympäristössä vanhainkodissa. CARE analysoi asiakkaiden liikkeitä ja toimintoja sekä visualisoi niistä korkeamman tason tietoa hoitajille. Kahden kuukauden kenttäkokeen tuloksena voidaan todeta, että järjestelmät yhdessä voivat auttaa hoitajia ymmärtämään asiakkaiden tarpeita sekä parantamaan hoidon laatua. Lähi-infrapunaspektroskopiaan perustuvalla kannettavalla ratkaisulla puolestaan hoitajat voivat varmistaa lääkehoidon oikeellisuuden. Tämä menetelmä on tarkempi ja parempi kuin tämänhetkiset käytössä olevat ratkaisut lääkkeiden oikeaksi toteamiseen. Väitöstyön keskusteluosuus palaa tutkimuskysymyksiin ja selventää, kuinka tehty työ ja saavutetut tulokset vastaavat niihin. Lisäksi keskustelu antaa yleiskuvan eri osapuolien näkemyksistä kehitetyn ratkaisun hyödyistä ja sen soveltuvuudesta käytännön työhön. Lopuksi väitöstyö luo katsauksen yhteistyön rooliin eri osa-alueiden toteuttamisessa ja esittää kriittisen näkökulman työn puutteisiin sekä yhteenvedon.
170

Near-Infrared Spectroscopy neurofeedback (NIRS neurofeedback) em crianças com Transtorno de Déficit de Atenção/Hiperatividade (TDAH)

Londero, Igor January 2015 (has links)
As intervenções com neurofeedback têm tido grande difusão na área como uma alternativa possível para tratamento do Transtorno de Déficit de Atenção/Hiperatividade (TDAH). Este estudo tem o objetivo de avaliar a viabilidade da utilização de um sistema de neurofeedback de baixo custo chamado Near Infrared Spectroscopy/Hemoencephalography Neurofeedback (NIR/HEG-NF) para tratar crianças com TDAH. Método: trata-se de um estudo clínico piloto aberto, que incluiu 5 crianças (3 meninos e 2 meninas - idade 10,4 ± 0,89 anos) com TDAH-C (tipo combinado). Os indivíduos completaram um programa de 24 sessões de NIR/HEG-NF, duas ou três vezes por semana. Os seguintes desfechos foram avaliados pré e pós-tratamento: 1) sintomas de desatenção e hiperatividade; 2) desempenho neuropsicológico; 3) imagens de SPECT cerebral; 4) qualidade de vida; e 5) efeitos adversos. Resultados: houve maior resistência do que o esperado para a participação dos indivíduos devido a vários fatores, tais como logísticos para a participação nas sessões e requerimento de não uso de medicação durante o protocolo. Detectamos uma diferença significativa na comparação pré e pós-intervenção nos escores atribuídos pelos pais na dimensão de hiperatividade e impulsividade do Swanson, Nolan and Pelham Questionnaire (SNAP-IV) (p = .042; tamanho de efeito [ES] =.38) e uma tendência de melhora nos escores atribuídos pelos pais e professores na dimensão desatenção (p = .066; ES = .47 / p = .068; ES = .60) naquelas crianças que finalizaram o tratamento. Detectamos uma tendência de aumento perfusional em diferentes partes do córtex cerebral em três indivíduos. As comparações pré e pós-intervenção nas outras medidas não indicaram diferenças estatisticamente significativas. Não foram relatados efeitos adversos significativos. Discussão: Os achados iniciais sugerem que o NIR/HEG-NF como tratamento para sintomas de TDAH pode ser promissor e deve ser melhor investigado. O protocolo lança luz sobre novas abordagens para avaliar a eficácia da intervenção. Pode-se, por exemplo, implementar o programa de intervenção no ambiente escolar e com uso concomitante de medicamentos para superar as resistências na alocação de pacientes e para uma avaliação com maior validade externa. / Background and objectives: Neurofeedback interventions have been quick and extensively introduced for clinicians to treat Attention-Deficit/Hyperactivity Disorder (ADHD). This study aims to assess the feasibility of using a low cost neurofeedback system called Near Infrared Spectroscopy/ Hemoencephalography Neurofeedback (NIR/HEG-NF) for treating children with ADHD. Method: This open pilot clinical study included 5 children (3 boys and 2 girls - age 10.4 ± 0.89 years) with ADHD-C (combined type). The subjects completed a program of 24 sessions of NIR/HEG-NF, two or three times a week. The following outcomes were assessed pre and post-treatment: 1) clinical symptoms of inattention and hyperactivity; 2) neuropsychological performance; 3) brain SPECT images; 4) quality of life and; 5) adverse effects. Results: Higher resistance than expected was experienced for patient allocation due to logistic reasons to attend the sessions in the hospital and the requirement of not using medication during the protocol. We detected a significant decrease in hyperactivity/impulsivity comparing pre and post-intervention scores in the parent’s Swanson, Nolan and Pelham Questionnaire - SNAP-IV (p = .042; Effect Size [ES] r = .38) and a trend of improvement in scores attributed by parents and teachers in inattention (p = .066; r = .47 / p = .068; r = .68) . We detected a trend for increased perfusion in different parts of the entire cortex in 3 subjects. Comparisons between pre and post-intervention scores in other measures did not suggest meaningful differences. No significant adverse effects were reported. Discussion: Our initial findings suggest that NIR/HEG-NF technique might be promising and should be further investigated. The protocol shed light on new approaches to assess the effectiveness of the intervention such as the need to both implement the intervention program in a school environment and to pursue the investigation of the treatment effects with concomitant use of medications to surpass resistances to enroll patients and to have an assessment with more external validity.

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