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1
Neirac, Lucie. "Learning with a linear loss function : excess risk and estimation bounds for ERM and minimax MOM estimators, with applications." Electronic Thesis or Diss., Institut polytechnique de Paris, 2023. http://www.theses.fr/2023IPPAG012.
Abstract:
La détection de communautés sur des graphes, la récupération de phase, le clustering signé, la synchronisation angulaire, le problème de la coupe maximale, la sparse PCA, ou encore le single index model, sont des problèmes classiques dans le domaine de l'apprentissage statistique. Au premier abord, ces problèmes semblent très dissemblables, impliquant différents types de données et poursuivant des objectifs distincts. Cependant, la littérature récente révèle qu'ils partagent un point commun : ils peuvent tous être formulés sous la forme de problèmes d'optimisation semi-définie positive (SDP). En utilisant cette modélisation, il devient possible de les aborder du point de vue classique du machine learning, en se basant sur la minimisation du risque empirique (ERM) et en utilisant la fonction de perte la plus élémentaire: la fonction de perte linéaire. Cela ouvre la voie à l'exploitation de la vaste littérature liée à la minimisation du risque, permettant ainsi d'obtenir des bornes d'estimation et de développer des algorithmes pour résoudre ces problèmes. L'objectif de cette thèse est de présenter une méthodologie unifiée pour obtenir les propriétés statistiques de procédures classiques en machine learning basées sur la fonction de perte linéaire. Cela s'applique notamment aux procédures SDP, que nous considérons comme des procédures ERM. L'adoption d'un “point de vue machine learning” nous permet d'aller plus loin en introduisant d'autres estimateurs performants pour relever deux défis majeurs en apprentissage statistique : la parcimonie et la robustesse face à la contamination adversaire et aux données à distribution à queue lourde. Nous abordons le problème des données parcimonieuses en proposant une version régularisée de l'estimateur ERM. Ensuite, nous nous attaquons au problème de la robustesse en introduisant un estimateur basé sur le principe de la "Médiane des Moyennes" (MOM), que nous nommons l'estimateur minmax MOM. Cet estimateur permet de faire face au problème de la robustesse et peut être utilisé avec n'importe quelle fonction de perte, y compris la fonction de perte linéaire. Nous présentons également une version régularisée de l'estimateur minmax MOM. Pour chacun de ces estimateurs, nous sommes en mesure de fournir un “excès de risque” ainsi que des bornes d'estimation, en utilisant deux outils clés : les points fixes de complexité locale et les équations de courbure de la fonction d'excès de risque. Afin d'illustrer la pertinence de notre approche, nous appliquons notre méthodologie à cinq problèmes classiques en machine learning, pour lesquels nous améliorons l'état de l'artCommunity detection, phase recovery, signed clustering, angular group synchronization, Maxcut, sparse PCA, the single index model, and the list goes on, are all classical topics within the field of machine learning and statistics. At first glance, they are pretty different problems with different types of data and different goals. However, the literature of recent years shows that they do have one thing in common: they all are amenable to Semi-Definite Programming (SDP). And because they are amenable to SDP, we can go further and recast them in the classical machine learning framework of risk minimization, and this with the simplest possible loss function: the linear loss function. This, in turn, opens up the opportunity to leverage the vast literature related to risk minimization to derive excess risk and estimation bounds as well as algorithms to unravel these problems. The aim of this work is to propose a unified methodology to obtain statistical properties of classical machine learning procedures based on the linear loss function, which corresponds, for example, to the case of SDP procedures that we look as ERM procedures. Embracing a machine learning view point allows us to go into greater depth and introduce other estimators which are effective in handling two key challenges within statistical learning: sparsity, and robustness to adversarial contamination and heavy-tailed data. We attack the structural learning problem by proposing a regularized version of the ERM estimator. We then turn to the robustness problem and introduce an estimator based on the median of means (MOM) principle, which we call the minmax MOM estimator. This latter estimator addresses the problem of robustness and can be constructed whatever the loss function, including the linear loss function. We also present a regularized version of the minmax MOM estimator. For each of those estimators we are able to provide excess risk and estimation bounds, which are derived from two key tools: local complexity fixed points and curvature equations of the excess risk function. To illustrate the relevance of our approach, we apply our methodology to five classical problems within the frame of statistical learning, for which we improve the state-of-the-art results
2
Faghihirad, Shervin. "Modelling of flows through hydraulic structures and interaction with sediment." Thesis, Cardiff University, 2014. http://orca.cf.ac.uk/62107/.
Abstract:
A three-dimensional layer integrated morphodynamic model has been developed to predict the hydrodynamic, sediment transport and morphological processes in a regulated reservoir. The model was based on an existing sediment transport model, with improvements being made. A bed evolution module based on the mass balance equation has been developed to determine the bed level change due to sediment transport. The horizontal eddy viscosity coefficient was equated to the depth averaged eddy viscosity, based on the horizontal velocity distribution while the vertical eddy viscosity coefficient was evaluated using the layer integrated form of the - equations. This scheme enhances the accuracy of the computed velocity and suspended sediment concentration distributions. The highly accurate ULTIMATE QUICKEST scheme was used to represent the advective terms in solving the advective-diffusion equation for suspended sediment transport. An explicit finite difference scheme has been developed for the bed sediment mass balance equation to calculate bed level changes. The numerical model was verified against laboratory data obtained from experiments in a trench and a partially closed channel. A physical model was constructed to represent the flow, sediment transport and morphodynamic processes in Hamidieh regulated reservoir. The physical model was designed based on the Froude similarity law and was undistorted. The model sediment size was determined in such a manner that the same ratio of particle fall velocity to shear velocity is maintained for both the model and prototype reservoir. Stokes law was used in calculating the particle fall velocity. The physical model results confirmed that the normal water surface elevation in the reservoir should increase by up to 25 cm in order to reach the nominal flow discharge diverted to the intakes. The numerical model was then applied to the scaled physical model of the reservoir and the associated water intakes and sluice gates. Various scenarios were tested to investigate the effects of different situations of diverting flow and sediment transport regimes, as well as to establish how these operations affect the morphodynamic processes in the reservoir and the vicinity of hydraulic structures. The model predictions agreed with measured data generally well. The numerical model results revealed the possibility of forming sedimentary islands in the regulated reservoir and it is uneconomical to set up a dredging zone near the one of the intakes. In summary, the integrated numerical and physical modelling approach showed many benefits and could help to optimize time and budget for design hydraulic structures. Key words: morphodynamic numerical model, turbulent flow, regulated reservoir, three- dimensional flow, laboratory tests.
3
Mihalyi, Agnes. "Screening for novel inhibitors of phospho-MurNAc-pentapeptide translocase MraY." Thesis, University of Warwick, 2014. http://wrap.warwick.ac.uk/62707/.
Abstract:
Bacterial drug resistance is an increasingly serious problem that threatens public health and researchers need to develop new drugs. The biosynthetic pathway of the bacterial peptidoglycan is a known and good target for the development of novel antibacterial agents. This research project focused on the first lipid-linked step of peptidoglycan biosynthesis. The enzyme required for this step is Phospho-MurNAc-pentapeptide Translocase MraY. Our aim was to screen for novel inhibitors of MraY. A continuous fluorescence MraY assay was developed and optimised to test known and potential inhibitors such as nucleoside natural products, antimicrobial peptides and structurally new small molecule potential inhibitors. The fluorescence assay was adapted to a high-throughput fluorescence assay in microtitre plate format and around 2,000 compounds were screened from the diversity set of the National Cancer Institute (NCI) against MraY in order to identify novel inhibitors. However, around 22 % of the test compounds from the diversity set interfered with fluorescence. Therefore, a radiochemical MraY assay was developed as an independent method. We eventually identified one potential MraY inhibitor from the diversity set, the naphthylisoquinoline alkaloid, michellamine B, with IC50 values of 400 and 340 μg/ml against E. coli and B. subtilis MraY respectively. The compound showed antibacterial activity against B. subtilis with an MIC value of 16 μg/ml. It was established that MraY inhibition from the pacidamycin producer, S. coeruleorubidus, was detectable directly from culture supernatants by the fluorescence and by the radiochemical MraY assays. Therefore, we tested culture supernatants and cell extracts from various Streptomyces strains. MraY inhibition was observed using cell extracts from Streptomyces venezuelae, and higher levels of inhibition were observed from a gbnB/gbnR S. venezuelae mutant, though it was not possible to identify the active species present. Following an earlier report of halogenated fluoresceins identified from a combined MraY/MurG screen, we also tested several halogenated fluoresceins, and found that phloxine B, a tetra-bromo fluorescein analogue, was an inhibitor of E. coli MraY with an IC50 value of 32 μM, and also inhibited MraY from P. aeruginosa, B. subtilis, M. flavus and S. aureus with IC50 values ranging between 100 and 210 μg/ml.
4
Ignasiak, Katarzyna. "Investigating antimicrobial resistance in the gut bacteria of insects feeding on plants." Thesis, University of East Anglia, 2016. https://ueaeprints.uea.ac.uk/62307/.
Abstract:
It has been previously described that antibiotic-resistant bacteria can be found in the guts of insects feeding on a variety of plants and not exposed to significant levels of antibiotics. Such naturally-occurring resistance has implications for clinically-relevant antibiotic resistance, which is a worldwide problem, and for using plants as a source of potential novel antibiotics. We investigated this phenomenon further. Firstly, we searched for antibiotic resistance in different insects’ guts and explored its origin, using two lepidopteran hosts feeding on artificial food containing either ciprofloxacin or oxytetracycline. We discovered that these antibiotics have a diverse impact on the insect gut microbiome, beyond simply inducing antibiotic resistance. Secondly, we used the insect gut bacteria to identify plant extracts with antibacterial activity, and purified their active fractions. We found that vindoline, from leaf extract, and serpentine, from root extract, are the most abundant metabolites in active fractions of Madagascar periwinkle extracts. Finally, we developed one of the insect species we used, Galleria mellonella, into a laboratory model for antibiotic efficacy testing, toxicity testing and as a model for human baby gut. In summary, in this project we explored different aspects of the antibiotic resistance that can be found in the insect gut and used it to guide us towards plant metabolites with antibacterial properties.
5
Pribadi, Aaron. "Algebraic Methods for Log-Linear Models." Scholarship @ Claremont, 2012. https://scholarship.claremont.edu/hmc_theses/41.
Abstract:
Techniques from representation theory (Diaconis, 1988) and algebraic geometry (Drton et al., 2008) have been applied to the statistical analysis of discrete data with log-linear models. With these ideas in mind, we discuss the selection of sparse log-linear models, especially for binary data and data on other structured sample spaces. When a sample space and its symmetry group satisfy certain conditions, we construct a natural spanning set for the space of functions on the sample space which respects the isotypic decomposition; these vectors may be used in algorithms for model selection. The construction is explicitly carried out for the case of binary data.
6
Donald, Claire Louisa. "Development of molecular tools to enhance understanding of antiviral RNAi in mosquitoes." Thesis, University of Glasgow, 2015. http://theses.gla.ac.uk/6207/.
Abstract:
Mosquito-borne arboviruses are a considerable threat to human and animal health across the world. Many of them are classed as emerging or remerging pathogens and the incidence of disease for a number of serious viral infections has increased as they expand their geographical and host ranges. As with other invertebrates, mosquitoes lack the adaptive immune response present in vertebrates and instead rely on their innate immune defences to modulate viral infections. Nevertheless, in contrast to vertebrates, arboviral infections in their arthropod vector are non-pathogenic and have no cytopathic effect or detrimental impact on their survival. The response considered to be the most important for antiviral defence in mosquitoes is RNA interference (RNAi) which is a sequence-specific, RNA silencing mechanism. Most of what is known about antiviral RNAi in arthropods has been established in Drosophila as the model insect organism. These studies have benefited from an extensive range of genetic mutants, molecular tools, reporter assays and genetic profiling. The absence of these tools for use in mosquito research is a substantial deficit for arboviral studies in their natural vector system and must be rectified in order to fully understand the influence vector immunity has on virus transmission. This thesis discusses the development of a ‘molecular tool-box’ for advancing the acquisition of knowledge in this area. Efficient RNAi gene silencing and its effect on the antiviral RNAi response was established in vitro using Semliki Forest virus (SFV) as model arbovirus. This assay determined that knock-down of Argonaute-2 had the most substantial impact on virus replication compared to the knockdown of other RNAi proteins. In addition, the limited detection of virus-derived small RNAs, key molecules of the antiviral RNAi response by Northern blot analysis provides further support to previous evidence that SFV may circumvent the antiviral response by sequestering its genomic RNA, resulting in restricted access by the RNAi machinery and preventing the generation of large quantities of virus-derived small RNAs. However, some SFV-derived small RNAs are known to be produced and these have been shown to generate a pattern of ‘hot’ and ‘cold’ spots along the full-length coding sequences. This thesis has determined that this pattern is not exclusive to viral-derived dsRNA trigger molecules but is also exhibited following the treatment of mosquito cells in culture with non-viral dsRNA. This implies that all exogenous dsRNA is processed by RNAi in a similar manner. This study has also characterised the presence of an RNA-dependent RNA polymerase (RdRP) encoded by Aedes aegypti mosquitoes. RdRPs are important for the amplification and spread of the RNAi signal in other organisms such as plants and worms; however, only one study suggested the existence of one in Drosophila. Although, this project proposed the presence and transcription of a homologue of the Drosophila RdRP in the Aedes aegypti-derived Aag2 cell line, protein knockdown assays revealed that it has no effect on virus replication in vitro; suggesting that it does not function as an RdRP. Due to the lack of antibodies against the major RNAi proteins Dicer-1, Dicer-2, Argonaute-1 and Argonaute-2 in mosquitoes, these were designed and screened which allowed the identification of several candidates for the detection of the proteins in mosquito cells in culture. Further to this, recombinant forms of the RNAi initiator protein Dicer-2 and the slicer protein Argonaute-2 were successfully generated and tested in vitro using different promoters to establish their use for future temporal and spatial kinetic studies. It was concluded that of the promoters tested the most successful for the expression of these reporter constructs was the subgenomic promoter of SFV. On the other hand a second promoter, the PUb promoter, may prove more suitable in the future. Finally, this project studied the antiviral capabilities of a non-haematophagous mosquito cell line which would not come across an arboviral infection by traditional blood- feeding routes. Instead the mosquito larvae sustain their adult life stages by feeding on the larvae of other species which may be vertically infected. A cell line derived from Toxorhynchites amboinensis was characterised and was shown to carry out RNAi if induced by dsRNA suggesting that they are able to mount an antiviral response to acquired infections. This study also determined that the cell line contains an endogenous insect specific virus and, although the source of this is unknown, it adds an interesting new dimension to mosquito antiviral immunity. This thesis enhances RNAi research in Aedes mosquitoes by presenting novel molecular tools and reporter assays which will be highly valuable for facilitating future investigations. The studies performed also add to what is already understood regarding the interaction between SFV and mosquito antiviral immunity through the RNAi response.
7
Kausar, Nighat. "Experimental spectroscopic and theoretical studies of amino acid derivatives." Thesis, University of Greenwich, 2008. http://gala.gre.ac.uk/6207/.
Abstract:
Experimental vibrational/electronic circular dichroism spectroscopic and theoretical studies of amino acid derivatives, i.e. N-acetyl-L-Asp, N-acetyl-L-Glu, and di-amino acid peptide/derivatives, i.e. L-Asp-L-Glu, a-N-acetyl-L-Asp-L-Glu, and ß-N-acetyl-L-Asp-L-Glu are reported. The calculated structures for N-acetyl-L-Asp and N-acetyl-L-Glu differ. The conformation of the trans amide moiety changes with the carbon chain length of the side chain of the amino acid derivatives. In the computed structures of N-acetyl-L-Asp and N-acetyl-L-Glu all backbone atoms are in-plane, except the side chain group; with respect to C2-C3 they both possess a staggered conformation. In addition both the N-acetyl and the side chain carboxylic acid groups are present in the anti-periplanar (i.e. anti- or trans-conformation). The amide I band occurs in the IR and Raman spectra of N-acetyl-L-Asp as a strong band at 1646 cm-1. In the case of N-acetyl-L-Glu it occurs as a weak, broad band at 1690 cm-1 in the solid state Raman spectrum; in the solution state Raman spectrum the amide I band is blue shifted, and presented at 1728 cm-1. The two different wavenumbers for C=O stretching vibrations, for both molecules, indicate that the two carboxylic acid groups are in different environments. According to DFT band assignments, the amide I bands are predicted at 1679 1682 cm-1 for N-acetyl-L-Asp and N-acetyl-L-Glu, respectively. A band due to the trans amide II mode is found at ˜1545 cm-1 for N-acetyl-L-Asp in the IR spectrum and for N-acetyl-L-Glu at ˜1575 cm-1 in both solid state IR and Raman spectra. The amide II mode is not observed in the solid or solution state Raman spectra of N-acetyl-L-Asp. In the solution state Raman spectrum of N-acetyl-L-Glu, the amide II mode is blue shifted and occurs at 1647 cm-1. The calculated wavenumber value for the amide II mode is ˜1482 cm-1 for both amino acid derivatives. The amide III mode for N-acetyl-L-Asp is found at 1229 cm-1 in both solid state IR and Raman spectra. In the solution state Raman spectrum, this is found as a very weak band at 1238 cm-1. This mode is not observed in the solid state IR and solution Raman spectra of N-acetyl-L-Glu, but it appears at 1233 cm-1 in the solid state Raman spectrum. According to DFT calculations, the amide III mode is predicted at ˜1210 cm-1 for both acetyl derivatives. The calculated vibrational spectra of L-Asp-L-Glu show a good fit with the experimentally recorded vibrational spectra. For example, the predicted and observed wavenumbers for amide I and amide II modes are similar i.e. observed values for amide I mode are at 1676 and 1692 cm-1 for solid state IR/Raman and solution state Raman spectra, respectively, and the predicted value is 1693 cm-1.
8
Scott, Ian Alexander. "Studies on seasonal variation in metabolic rate related to changes in body composition with particular reference to shorebirds (Charadrii)." Thesis, Durham University, 1992. http://etheses.dur.ac.uk/6207/.
Abstract:
The basal metabolic rate of three species of shorebird was measured throughout the non-breeding season. These measurements were related to change in body mass and body composition. No seasonal pattern in BMR was apparent after variation related to changes in body mass and body composition had been accounted for. Seasonal variation in body mass of captive Grey Plover and Redshank was found to resemble that of the same species in the wild. This was not so for Sanderling. Body composition changes were either inferred from destructive analysis, or measured using a technique known as total body electrical conductance (TOBEC). The intraspecific relationship between TLM (Total lean mass) and TOBEC index was found to be best described by a linear equation. Separate intraspecific allometric equations were derived relating BMR to body mass for two shorebird and one wildfowl species. The mass exponents in these equations were found to be 1.03, 0.62 and 0.61 for Redshank, Grey Plover and Wigeon respectively. The results were related to the current interpretations of the BMR/body mass exponent. The within-individual BMR/body mass relationship was investigated for Redshank and Grey Plover. The mean mass exponent was found to be 1.23 and 0.92 respectively. No significant relationship was found for any individual Sanderling. Variation in BMR within an individual was related to variation in body composition. In most cases variation in body fat was found to be the most important predictor of within-individual variation in metabolic rate. In Vitro determinations of the oxygen uptake of avian fat, liver and muscle tissues indicated that the energy consumption of fat was less than one tenth that of liver and muscle. This indicates that within-individual increases in BMR with increased levels of fat are probably associated with increased metabolic output of the lean tissues.
9
Scarpino, A. L. "Pain body : writing at the intersection of elegy and witness." Thesis, Bath Spa University, 2014. http://researchspace.bathspa.ac.uk/6207/.
Abstract:
This thesis contains a creative and critical component. Written at the intersection of two poetics forms, elegy and poetry of witness, the creative piece, a book-length poem titled 'Pain Body', weaves together personal writing based on my experience with chronic pain, 'found' poetry that grounds my experience in larger conversations about the body and illness, and mythically-minded writing about the ash tree. In the critical component, I identify the intersection of elegy and poetry of witness as having four defining characteristics: it is situated in what Carolyn Forche terms the 'social' sphere, it is firmly located in the body, it refuses consolation, and it demonstrates a fragmented and wounded language. I then discuss the poets Paul Monette and Audre Lorde as exemplars of writing at this intersection, as they elegize a loved one (Monette) and their own body (Lorde) while bearing witness to the AIDS epidemic (Monette) and growing cancer epidemic (Lorde). Finally, I examine the ways in which my writing in 'Pain Body' also exemplifies this intersection. My critical research thus shapes my creative writing, while extending and refining current scholarly conversations about elegy and witness.
10
Rizzo, Stefano Giovanni. "Una base dati per il knowledge discovery in genetica medica." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2013. http://amslaurea.unibo.it/6207/.
Abstract:
L'innovazione delle tecnologie di sequenziamento negli ultimi anni ha reso possibile la catalogazione delle varianti genetiche nei campioni umani, portando nuove scoperte e comprensioni nella ricerca medica, farmaceutica, dell'evoluzione e negli studi sulla popolazione.
La quantità di sequenze prodotta è molto cospicua, e per giungere all'identificazione delle varianti sono necessari diversi stadi di elaborazione delle informazioni genetiche in cui, ad ogni passo, vengono generate ulteriori informazioni.
Insieme a questa immensa accumulazione di dati, è nata la necessità da parte della comunità scientifica di organizzare i dati in repository, dapprima solo per condividere i risultati delle ricerche, poi per permettere studi statistici direttamente sui dati genetici.
Gli studi su larga scala coinvolgono quantità di dati nell'ordine dei petabyte, il cui mantenimento continua a rappresentare una sfida per le infrastrutture.
Per la varietà e la quantità di dati prodotti, i database giocano un ruolo di primaria importanza in questa sfida. Modelli e organizzazione dei dati in questo campo possono fare la differenza non soltanto per la scalabilità, ma anche e soprattutto per la predisposizione al data mining. Infatti, la memorizzazione di questi dati in file con formati quasi-standard, la dimensione di questi file, e i requisiti computazionali richiesti, rendono difficile la scrittura di software di analisi efficienti e scoraggiano studi su larga scala e su dati eterogenei.
Prima di progettare il database si è perciò studiata l’evoluzione, negli ultimi vent’anni, dei formati quasi-standard per i flat file biologici, contenenti metadati eterogenei e sequenze nucleotidiche vere e proprie, con record privi di relazioni strutturali. Recentemente questa evoluzione è culminata nell’utilizzo dello standard XML, ma i flat file delimitati continuano a essere gli standard più supportati da tools e piattaforme online.
È seguita poi un’analisi dell’organizzazione interna dei dati per i database biologici pubblici. Queste basi di dati contengono geni, varianti genetiche, strutture proteiche, ontologie fenotipiche, relazioni tra malattie e geni, relazioni tra farmaci e geni. Tra i database pubblici studiati rientrano OMIM, Entrez, KEGG, UniProt, GO. L'obiettivo principale nello studio e nella modellazione del database genetico è stato quello di strutturare i dati in modo da integrare insieme i dati eterogenei prodotti e rendere computazionalmente possibili i processi di data mining.
La scelta di tecnologia Hadoop/MapReduce risulta in questo caso particolarmente incisiva, per la scalabilità garantita e per l’efficienza nelle analisi statistiche più complesse e parallele, come quelle riguardanti le varianti alleliche multi-locus.
11
Miserocchi, Anna <1983>. "Analisi dei meccanismi patogenetici alla base del danno vascolare Hiv-indotto." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2014. http://amsdottorato.unibo.it/6207/.
Abstract:
L'infezione da HIV-1 resta ancora oggi una delle principali problematiche nell'ambito della sanità mondiale, con circa 35 milioni di individui infetti in tutto il mondo. L'introduzione della terapia antiretrovirale combinata (cART) ha drasticamente modificato l’evoluzione di questa infezione, che da patologia a sviluppo terminale dopo alcuni anni dalla trasmissione, è diventata una patologia cronica con una lunga aspettativa di vita per i pazienti. Tuttavia, la cART non è in grado di eradicare l’infezione e nei pazienti HIV-infetti trattati è possibile notare un aumento della comparsa di comorbidità, tra le quali le più frequentemente riscontrate sono lesioni al sistema nervoso centrale, ai reni, al tessuto osseo, al fegato e al sistema cardiovascolare.
I danni al sistema cardiocircolatorio derivano da una serie di concause virologiche, comportamentali, ambientali e farmacologiche che alterano la parete vascolare, il metabolismo dei lipidi e la regolazione della coagulazione, inducendo la formazione di lesioni strutturali di tipo aterosclerotico che sono alla base dell’aumentata incidenza di infarti, ictus e alterazioni del circolo osservabili nei pazienti HIV-positivi.
Dalla recente letteratura è emerso come l’omeostasi del tessuto endoteliale sia regolata anche a livello delle cellule staminali mesenchimali (MSC) presenti nella parete vascolare. Per questo abbiamo voluto analizzare possibili effetti dell’infezione di HIV, delle sue proteine e di alcune molecole antiretrovirali sulla vitalità e sul differenziamento delle MSC purificate dalla parete arteriosa umana.
I risultati ottenuti indicano come l’infezione da HIV e l’azione delle proteine gp120 e Tat attivino il meccanismo di apoptosi nelle MSC e una profonda alterazione nel differenziamento verso la filiera adipocitaria e verso quella endoteliale. Inoltre, alcune molecole ad azione antiretrovirale (in particolare specifici inibitori della proteasi virale) sono in grado bloccare il differenziamento delle MSC verso le cellule endoteliali. Dall’insieme di queste osservazioni emergono nuovi meccanismi patogenetici correlati al danno cardiovascolare riscontrato nei pazienti HIV-positivi.HIV-1 infection remains nowadays a major problem of health worldwide. The introduction of a combined antiretroviral therapy (cART) has greatly improved life expectancy of HIV-infected patients. However, cART cannot eradicate the infection and HIV-infected patients show different comorbidities, like central nervous system lesions, osteoporosis, renal and liver dysfunction and cardiovascular pathologies. Cardiovascular damages come from viral mechanisms and pharmacological interactions and their frequency is enhanced in HIV-positive patients. Mesenchymal stem cells (MSC) are very important for endothelial homeostasis, therefore we decided to analyze the effects of HIV and cART in these cells. Our results show that HIV-1 and its proteins gp120 and Tat increase MSC apoptosis and alter MSC differentiation towards endothelial and adipogenic lineages. Moreover, also antiretroviral molecules, in particular protease inhibitors, disrupt MSC differentiation regulation.
12
Vincart-Emard, Alexandre. "Numerical investigation of spatial inhomogeneities in gravity and quantum field theory." Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/62607.
Abstract:
Many interesting phenomena, such as high-temperature superconductivity and the quark-gluon plasma, still lack a satisfyingly predictive theoretical description. However, recent advances have revealed a curious connection between quantum field theories at strong coupling and classical gravity. This correspondence, known as the gauge/gravity duality or holographic correspondence, offers a promising perspective for investigating strongly correlated systems. In this thesis, we focus on using these new tools to examine the consequences of breaking translational invariance in such systems.
We first use this duality to study the holographic realization of a spatially inhomogeneous condensed matter device known as a Josephson junction. We do so by constructing the gravitational equivalent of two superconductors separated by a weak metallic link, from which we then extract various field-theoretic quantities of interest. These include the spontaneously generated Josephson current, the superconducting order parameter, as well as a novel quantity we refer to as edge currents, which are indicative of gapless chiral modes localized at the interfaces between phases.
We then investigate the more abstract construct of entanglement entropy in holographic theories. We model the fast local injection of energy in a 2+1 dimensional field theory and study the resulting thermalization of quantum entanglement. We achieve this objective by numerically evolving the geometry dual to a local quench from which we then compute the area of various minimal surfaces, the holographic proxy for entanglement entropy. We observe the appearance of a lightcone featuring two distinct regimes of entanglement propagation and provide a phenomenological explanation of the underlying mechanisms at play.
Finally, we turn our attention to spatial inhomogeneities in gravitational systems themselves. We use an approximation of general relativity in which the number of spacetime dimensions is infinite to investigate the Gregory-Laflamme instability of higher-dimensional charged black branes. We argue that charged branes are always unstable in this new language, and push the approximation to next-to-leading order to compute the critical dimension below which the instability results in horizon fragmentation. We also examine the stability properties of two-dimensional black membranes and find that the triangular lattice minimizes brane enthalpy.Science, Faculty of
Physics and Astronomy, Department of
Graduate
13
Cheung, Walden A. "Selecting quality indicators for pulmonary rehabilitation programs in Canada : a modified RAND Appropriateness Method study." Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/62807.
Abstract:
Pulmonary rehabilitation (PR) is a comprehensive intervention of self-management education and exercise training that improves quality of life, exercise tolerance, symptoms of dyspnea, and reduces the risk of hospitalization in patients living with chronic respiratory diseases such as chronic obstructive pulmonary disease, asthma, lung cancer, and interstitial lung disease. Despite the proven benefit of pulmonary rehabilitation, recent studies have found notable inconsistencies in its organization and delivery. Inconsistencies within clinical practice are likely to affect the quality in the delivery of pulmonary rehabilitation. Quality indicators (QIs) are tools similar to a checklist that can potentially remediate these concerns. While other jurisdictions have created quality indicators for pulmonary rehabilitation programs, their methodological approach to developing these quality indicators is questionable. This study developed 56 quality indicators with a rigorous approach using a modified RAND Appropriateness Method. A panel comprising twelve PR healthcare professionals and stakeholders was created to create a list of QIs. The panel rated each indicator based on four criteria (importance, scientific soundness, reliability, and feasibility) and listed which indicator they believed could determine a quality pulmonary rehabilitation program. This study recommends that the 56 QIs, based upon consensus, be used for operationalizing the evaluation and auditing of PR programs as well as for establishing clinical benchmarks.Medicine, Faculty of
Graduate
14
Laver, Christopher R. J. "Ocular tissue engineering : rebuilding the retina with stem cells." Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/62907.
Abstract:
The full abstract for this thesis is available in the body of the thesis, and will be available when the embargo expires.Medicine, Faculty of
Experimental Medicine, Division of
Medicine, Department of
Graduate
15
Kaya, Firat Ayse. "Early growth technology analysis : case studies in solar energy and geothermal energy." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/62107.
Abstract:
Thesis (S.M. in Technology and Policy)--Massachusetts Institute of Technology, Engineering Systems Division, Technology and Policy Program, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 85-87).
Public and private organizations try to forecast the future of technological developments and allocate funds accordingly. Based on our interviews with experts from MIT's Entrepreneurship Center, Sloan School of Management, and IBM, and review of literature, we found out that this important fund allocation process is dominated by reliance on expert opinions, which has important drawbacks alongside its advantages. In this Thesis, we introduce a data-driven approach, called early growth technology analysis, to technology forecasting that utilizes diverse information sources to analyze the evolution of promising new technologies. Our approach is based on bibliometric analysis, consisting of three key steps: extraction of related keywords from online publication databases, determining the occurrence frequencies of these keywords, and identifying those exhibiting rapid growth. Our proposal goes beyond the theoretical level, and is embodied in software that collects the required inputs from the user through a visual interface, extracts data from web sites on the fly, performs an analysis on the collected data, and displays the results. Compared to earlier software within our group, the new interface offers a much improved user experience in performing the analysis. Although these methods are applicable to any domain of study, this Thesis presents results from case studies on the fields of solar and geothermal energy. We identified emerging technologies in these specific fields to test the viability of our results. We believe that data-driven approaches, such as the one proposed in this Thesis, will increasingly be used by policy makers to complement, verify, and validate expert opinions in mapping practical goals into basic/applied research areas and coming up with technology investment decisions.
by Ayse Kaya Firat.
S.M.in Technology and Policy
16
Lovell, Nathan Gary. "Control of size and charge selectivity in amphiphilic graft copolymer nanofiltration membranes." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/62607.
Abstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2010.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student submitted PDF version of thesis.
Includes bibliographical references (p. 99-106).
The throughput and efficiency of membrane separations make polymer filtration membranes an important resource for the pharmaceutical, food and wastewater treatment industries. Nanofiltration (NF) membranes fill an important niche between nonporous reverse osmosis membranes, which have comprehensive solute rejection and low solvent permeability, and porous sieving ultrafiltration membranes. However, challenges in NF membrane design remain outstanding. At the effective pore size of NF membranes (~0.5 nm-2 nm), both electrostatic and steric factors determine membrane selectivity. Most NF membranes are charged under a wide range of environmental conditions and thus preferentially exclude charged solutes. This charge selectivity precludes separation of molecules based solely on size. An additional limitation of NF membranes is the tendency to foul by adsorption of feed components. The purpose of this thesis is to demonstrate control of membrane selectivity in fouling resistant membranes via manipulation of the chemistry of a specific copolymer system, polyacrylonitrile (PAN)-based poly(ethylene oxide) (PEO) graft polymers. Previous work with amphiphilic graft copolymers as membrane materials has included PANg- PEO with an average graft length of 9 (PAN-g-PEO9). PAN-g-PEO9 was shown to have excellent fouling resistance as an antifouling additive in porous ultrafiltration membranes and as a dense selective layer coated onto a support base membrane-a thin-film composite (TFC) NF membrane. The comb morphology of the polymer imposes high interfacial area on the microphase-separated domains, resulting in a bicontinuous structure consisting of a glassy PAN matrix interpenetrated by PEO-filled "nanochannels" that can act as vias for water and small solutes (with a size cutoff of ~0.8 nm). It also presents a PEO brush on the comb surface which acts as a steric barrier to resist irreversible fouling of the membranes. The understanding from previous work on PEO comb NF membranes is that the pore size is determined by the nanochannel's size, i.e. the PEO domain size. Because the graft characteristics (spacing and length) of comb copolymers determine the domain size, it was expected that varying the graft length would allow broad, precise control of the size cutoff of the TFC membranes, a concept demonstrated previously with amphiphilic graft copolymer NF membranes of poly(vinylidene fluoride)-graft-poly(oxyethylene methacrylate) (PVDF-g-POEM). The first aim of this thesis was to tailor the retention properties of PAN-g-PEO TFC NF membranes by modifying the chemistry to tune the electrostatic and steric properties sufficiently to enable complex separations, particularly of solutes with high fouling potential. Comb copolymers incorporating ~40 weight % PEO with side chains varying from 5-40 EO units were synthesized by free radical methods and compared as selective-layer coatings on PAN UF membranes. 3 Membranes incorporating combs with 9 EO units or more were shown to resist irreversible fouling when challenged by a model protein feed solution (bovine serum albumin) for 24 hours. Fouling resistance was found to be compromised, however, upon exposure to acid (pH 2) solution, used to simulate chemical cleaning procedures in industry. Thickness-normalized permeabilities of these PAN-g-PEOn NF membranes exceeded those of commercially available NF membranes by approximately an order of magnitude. A systematic effect of side chain length on permeability was seen when varying temperature, ionic strength, and pressure. Contrary to expectations, the membrane size cutoff (~0.8 nm) for charged rigid molecular probes in deionized water was independent of the comb side chain length. This new finding can be explained by modeling the hydrophilic domains as opposing swollen polymer brushes of uniform density acting as a physical gel. The gel mesh size (distance between chains) is independent of side chain length, and controls the size cutoff in good solvent conditions matching those in which the membrane was equilibrated during fabrication. In poorer solvent conditions, a decrease in the brush height, progressing to complete collapse of the PEO gel, can be expected to create differentiation based on domain size (i.e. side chain length). This is consistent with the finding that retentions of dyes increased with decreasing side chain length in saline solution, as salt is known to reduce PEO-water miscibility. Fluorescently labeled peptides germane to proteomics research were filtered and both chromatographic and size-selective membrane behavior was observed-the first demonstration of size-based nanofiltration of peptides. Based on this finding, two different peptides of molecular weights 1.3kDa and 1.5kDa were fractionated to achieve a six-fold increase in the concentration of the larger peptide relative to the smaller peptide in two filtration steps. The electrostatic selectivity of the PEO comb membranes could also be varied. Terpolymers consisting of PAN-g-PEO with 1-2% charged sulfopropyl acrylate (SPA) or 5% N,Ndimethyl- N-(2-methacryloyloxyethyl-N-(3-sulfopropyl) ammonium betaine (SPE) were synthesized and coated onto PAN base membrane. The divalent salt (Na2SO4) retention of the resulting TFC membranes increased from ~20% for the PAN-g-PEO copolymer to ~45% and 82% for the SPE and SPA terpolymers, respectively. Retention of monovalent NaCl was substantially lower, characteristic of commercial NF membranes. The charged comb membranes did not completely resist fouling by a 1 g/L BSA solution, losing 2% of the initial flux after 24 h exposure. Forming a trilayer TFC, with a layer of PAN-g-PEO coated over a charged terpolymer, reduced membrane fouling compared to the charged layer alone. In summary, the goal of this study was to demonstrate control of membrane selectivity in fouling-resistant PAN-g-PEO NF membranes. An important finding was that the PEO gel created in the hydrophilic domains leads to similar size cutoffs over a wide range of side chain length. To access the desired spectrum of size cutoffs, the quality of solvent for the swollen PEO brush must be reduced. In spite of these limitations, the membrane was shown to have useful fractionating properties as demonstrated with labeled peptides of varying molecular weight. The retention of salts was enhanced by incorporating small amounts of charged monomer into the comb backbone, but at the expense of fouling resistance.
by Nathan Gary Lovell.
Ph.D.
17
Wongso, Ricolas. "An application of Value Stream Mapping to reduce lead time and WIP in a make-to-order manufacturing line." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/62507.
Abstract:
Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 57).
Significant growth in the sales is expected in the coming years for the product family that is the focus of this research. In order to meet the takt time for the future demand, improvement on the current processes and expansion are needed. In this work, Value Stream Mapping was implemented to identify the bottleneck processes: fit up (oval), full welding, and pressure testing. Assembly cell concept, workload balancing and FIFO lanes were proposed countermeasures or improvements to address the capacity shortfall. A decrease of 27% in manufacturing lead time was projected if these improvements were made. In addition, the capacity analysis suggests that an expansion is required in full welding and heat treatment furnace.
by Ricolas Wongso.
M.Eng.
18
Dougherty, Tom (Tom J. ). "Help! not just anybody : essays on altruism and conflicts of interest." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/62407.
Abstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Linguistics and Philosophy, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 54-56).
If you can help someone without detriment to your interest, nor anyone else's interest, then it is clear that you ought to do so. But things are not always so easy. When there is a conflict of interest, you have to decide what to do. Whom should you help when you cannot help everyone? How much should you sacrifice to help others? May you expose people to risks when helping them? This dissertation addresses aspects of these questions. You ought to save a larger group of people rather than a distinct smaller group of people, all else equal. Why? Chapter 1, "Rational Numbers," offers an explanation. Its two parts can be roughly summarized as follows. First, you are morally required to want each person's survival for its own sake. Second, you are rationally required to achieve as many of these ends as possible, if you have these ends. Chapter 2, "Ambition and Altruism in the Dynamic Moral Life," poses a puzzle. We would like an account of beneficence to be moderately demanding, and yet still to require you to be ambitious with your altruism. How can these diverging desiderata be simultaneously met? Drawing on empirical work, the chapter defends the following solution: beneficence requires you to develop morally, and increase how much you give over time. Chapter 3, "Chancy Charity and Aggregative Altruism," argues that two initially attractive claims are inconsistent. First, you must save someone's life rather than cure the headaches of many. Second, you may take a small risk of someone's death when curing this person's headache. Since we are unable to hold both these claims, we are in danger of lacking an explanation of some common intuitions about risk and the priority of serious needs. A candidate explanation is considered, but criticized.
by Tom Dougherty.
Ph.D.
19
Allemann, Frank von Arx. "Swedish institutional investors : potential role in U.S. real estate in the next five years." Thesis, Massachusetts Institute of Technology, 1991. http://hdl.handle.net/1721.1/62907.
20
Prabhat, Naveen. "Critical evaluation of anomalous thermal conductivity and convective heat transfer enhancement in nanofluids." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/62707.
Abstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 100-111).
While robust progress has been made towards the practical use of nanofluids, uncertainties remain concerning the fundamental effects of nanoparticles on key thermo-physical properties. Nanofluids have higher thermal conductivity and single-phase heat transfer coefficients than their base fluids. The possibility of very large thermal conductivity enhancement in nanofluids and the associated physical mechanisms are a hotly debated topic, in part because the thermal conductivity database is sparse and inconsistent. This thesis reports on the International Nanofluid Property Benchmark Exercise (INPBE) in which the thermal conductivity of identical samples of colloidally stable dispersions of nanoparticles, or 'nanofluids', was measured by over 30 organizations worldwide, using a variety of experimental approaches, including the transient hot wire method, steady-state methods and optical methods. The nanofluids tested were comprised of aqueous and non-aqueous basefluids, metal and metal oxide particles, near-spherical and elongated particles, at low and high particle concentrations. The data analysis reveals that the data from most organizations lie within a relatively narrow band (± 10% or less) about the sample average, with only few outliers. The thermal conductivity of the nanofluids was found to increase with particle concentration and aspect ratio, as expected from classical theory. The effective medium theory developed for dispersed particles by Maxwell in 1881, and recently generalized by Nan et al., was found to be in good agreement with the experimental data. The nanofluid literature contains many claims of anomalous convective heat transfer enhancement in both turbulent and laminar flow. To put such claims to the test, we have performed a critical detailed analysis of the database reported in 12 nanofluid papers (8 on laminar flow and 4 on turbulent flow). The methodology accounted for both modeling and experimental uncertainties in the following way. The heat transfer coefficient for any given data set was calculated according to the established correlations (Dittus-Boelter's for turbulent flow and Shah's for laminar flow). The uncertainty in the correlation input parameters (i.e. nanofluid thermo-physical properties and flow rate) was propagated to get the uncertainty on the predicted heat transfer coefficient. The predicted and measured heat transfer coefficient values were then compared to each other. If they differed by more than their respective uncertainties, we called the deviation anomalous. According to this methodology, it was found that in nanofluid laminar flow in fact there seems to be anomalous heat transfer enhancement in the entrance region, while the data are in agreement (within uncertainties) with the Shah's correlation in the fully developed region. On the other hand, the turbulent flow data could be reconciled (within uncertainties) with the Dittus-Boelter's correlation, once the temperature dependence of viscosity was included in the prediction of the Reynolds number. While this finding is plausible, it could not be directly confirmed, because most papers do not report information about the temperature dependence of the viscosity for their nanofluids.
by Naveen Prabhat.
S.M.
21
Velázquez, Díaz Tifanny, and Díaz Tifanny Velázquez. "Reforma al Artículo 181 de la Ley Agraria." Tesis de Licenciatura, Universidad Autónoma del Estado de México, 2016. http://hdl.handle.net/20.500.11799/62907.
Abstract:
La presente tesis versará sobre la propuesta de reforma que planteo al artículo 181 de la Ley Agraria, en el sentido de facultar a los Tribunales Unitarios Agrarios para tener por no interpuesta la demanda agraria.
El tema expuesto en líneas anteriores, lo presento al observar que se tiene un inequilibrio procesal de las partes al momento de emitirse un auto de prevención, teniendo como consecuencia que los sujetos agrarios no cuentan con una debida certeza jurídica, en el sentido de que el juzgador agrario no tiene la facultad de tener por no interpuesto el escrito inicial, conforme a lo establecido en el artículo 181 de la Ley Agraria, viéndose limitado el magistrado en sus facultades, restando con ello autonomía al no poder sancionar sus propias determinaciones en el auto de prevención.
22
Guimarães, Joana Alexandra Carvalho. "Patogénese da artrite idiopática juvenil sistémica. Papel da imunidade inata." Master's thesis, Instituto de Ciências Biomédicas Abel Salazar, 2010. http://hdl.handle.net/10216/62307.
23
Pereira, Cátia Marisa Loureiro. "A simulação como metodologia de aquisição de competências na formação médica pré-graduada." Master's thesis, Instituto de Ciências Biomédicas Abel Salazar, 2010. http://hdl.handle.net/10216/62207.
24
Dames, Michael Henri. "Factors influencing estuarine and coastal connectivity of an estuarine-dependent fishery species, Pomadasys commersonnii (Haemulidae)." Thesis, Rhodes University, 2018. http://hdl.handle.net/10962/62307.
25
Spohr, Fúlvia da Silva. "Tecendo imagens : operando experiências no plano do "comum"." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2011. http://hdl.handle.net/10183/62107.
Abstract:
Este trabalho conta como uma experiência com tecnologias videográficas produziu efeitos nos modos de coordenar ações, produzir distinções e nas emoções de um grupo de trabalhadores e usuários de um serviço de saúde mental, o CAPS II Cais Mental Centro/POA. A Oficina de Imagens é uma atividade terapêutica onde ocorre a produção de imagens que podem resultar em filmes. A ideia central do trabalho gira em torno dos efeitos surgidos a partir da problematização sobre uma série de imagens videográfica produzidas pelo coletivo da Oficina postas ao descarte, e de outras, a serem aproveitadas para construção de um filme. O grupo é tomado por um estranhamento sobre que imagens poderiam ou não compor um filme. Na Oficina de Edição, foi proposto utilizar as imagens descartadas nonsense, ou seja, aquelas desfocadas, tremidas ou fora de enquadre para a construção de um ―outro‖ vídeo – sendo possível, portanto, incluir o que, em um primeiro momento, fora excluído. A edição foi realizada pelo grupo no editor de imagens digital Windows Movie Maker. Esse processo possibilitou produzir deslocamentos e modulações nas redes de conversação entre os participantes. É a partir dessa experiência, que o convidamos a acompanhar, através do efeito patckwork (recurso narrativo), os deslocamentos operativos que se produziram nestes encontros, nestas redes de conversação. Assim, em uma perspectiva metodológica de pesquisa-intervenção, apresentamos alguns deslocamentos, produzidos no fazer com a Oficina de Edição de Imagens. Esse encontro dos integrantes da Oficina com o computador, o editor de imagens, as imagens descartadas, as redes de conversação se dá na ação, no fazer que potencializa a inserção social, autoria e a construção de outros modos de relação com a saúde/loucura, constituindo um plano de compartilhamento e também político, ao operar experiências no plano do "comum".The main objective of this study is to report how an experience with video technology changed the way the actions were coordinated, the distinctions and emotions are produced in the group of people who work and use the mental health service, o CAPS II Cais Mental Centro/POA. The Image Workshop is a therapeutic activity, in which there are image productions, and they can be transformed into many films. The research focuses on the effects that are trigged through the problematization, concerned to a serie of video images, produced by the group that participated of the Workshop, that were discarded, as well as on the others that were used in the construction of a film. The group was not sure which images could be used in the film. At the Editing Workshop, it was suggested that the discarded images, the nonsense ones, could be used: the ones that were blurred, blur and did not fit in the construction of a video, so we concluded that it was possible to add what was considered firstly something excluded. Editing was performed by the group in the digital image editing, through the Windows Movie Maker. The process trigged many other networks for dialogue, different from the one that was constructed at the Image Workshop inicially, but we cannot consider the former more or less important than the recently produced, they were just seen as new and an opportunity to share experiencies. So, we invit the reader to follow, through the pachwork effect (a narrative resource), the operative replacement that were produced in the Workshops, in the network dialogues. Thus, through a methodological perspective of an intervention research, we present some of the replacement, produced at Editing Image Workshop. The experience that the participants of the group had with the computer, the editing and discarted images, changed the networks for dialogue, that were performed in the action and while the images were produced, so that they develop social inclusion, authorship and the construction of many other ways to deal with health/mental illness, building a new plan of sharing and also political, when many experiences were operated in a level whose experience were shared by all the participantes.
26
Nabbosa, Racheal. "Assessing the use of journals and formats preferred by postgraduate students of Makerere University." Diss., University of Pretoria, 2013. http://hdl.handle.net/2263/62107.
Abstract:
Academic libraries are focused towards effective information provision that is necessary for teaching, learning and research. Makerere University Library (Maklib) is no exception as it has strategies towards effective provision of information resources. Journals are some of the resources that are provided by the library to support teaching, learning and research and they are provided in two formats: namely, the electronic format and the print format. This research attempted to investigate whether postgraduate students use these journals and the formats they prefer to access. Research was conducted involving 114 postgraduate students using questionnaires as the data collection tool. Qualitative data was collected, analysed using Google Forms and presented in graphs, tables and text. Findings revealed that most postgraduate students are aware of the existence of journals provided by the library although some expressed a lack of awareness. Further still they use the journals provided and most of them have preference for the electronic format of journals. However it was also revealed that access was hindered by several factors such as long procedures to access the library. Recommendations that need to be adopted by Maklib are also discussed such as increasing on awareness campaigns, continuous training of students and staff and providing the necessary infrastructure to enhance access to the journals.Mini Dissertation (MIT)--University of Pretoria, 2015.
Information Science
MIT
Unrestricted
27
van, der Walt Rhyno Lambertus Reyneke. "Photovoltaic based distributed generation power system protection." Diss., University of Pretoria, 2017. http://hdl.handle.net/2263/62807.
Abstract:
In recent years, the world has seen a significant growth in energy requirements. To meet this
requirement and also driven by environmental issues with conventional power plants, engineers
and consumers have started a growing trend in the deployment of distributed renewable power
plants such as photovoltaic (PV) power plants and wind turbines. The introduction of distributed
generation pose some serious issues for power system protection and control engineers. One of
the major challenges are power system protection. Conventional distribution power systems take
on a radial topology, with current flowing from the substation to the loads, yielded unidirectional
power flow. With the addition of distributed generation, power flow and fault current
are becoming bi-directional. This causes loss of coordination between conventional overcurrent
protection devices. Adding power sources downstream of protection devices might also cause
the upstream protection device to be blinded from faults. Conventional overcurrent protection
is mainly based on the fault levels at specific points along the network. By adding renewable
sources, the fault levels increase and become dynamic, based on weather conditions.
In this dissertation, power system faults are modelled with sequence components and simulated
with Digsilent PowerFactory power system software. The modeling of several faults under varying power system parameters are combined with different photovoltaic penetration levels
to establish a framework under which protection challenges can be better defined and
understood. Understanding the effects of distributed generation on three phase power systems
are simplified by modeling power systems with sequence networks. The models for
asymmetrical faults shows the limited affect which distributed generation has on power system
protection. The ability of inverter based distributed generators to provide active control of phase
current, irrespective of unbalanced voltage occurring in the network limits their influence during
asymmetrical faults. Based on this unique ability of inverter based distributed generators (of
which PV energy sources are the main type), solutions are proposed to mitigate or prevent the
occurrence of loss of protection under increasing penetration levels of distributed generation.
The solutions include using zero and negative sequence overcurrent protection, and adapting the
undervoltage disconnection time of distributed generators based on the unique network
parameters where it is used. Repeating the simulations after integrating the proposed solutions
show improved results and better protection coordination under high penetration levels of PV
based distributed generation.Dissertation (MEng)--University of Pretoria, 2017.
Electrical, Electronic and Computer Engineering
MEng
Unrestricted
28
Sutton, Sindi. "Communicative dispositions of Foundation Phase Afrikaans-speaking teachers using English as medium of instruction." Diss., University of Pretoria, 2017. http://hdl.handle.net/2263/62907.
Abstract:
Education in South Africa has experienced many changes since the dawn of democracy in 1994. The demographic composition of schools has changed dramatically as urbanisation has increased and the movement of people is no longer regulated by Apartheid laws. Classrooms now are multi-lingual and multi-cultural with learners from diverse socio-economic backgrounds. Many senior teachers at Ditlou Primary School started their teaching careers more than 20 years ago and were trained to work within an almost homogeneous school context, using their mother tongue - Afrikaans - exclusively as the medium of instruction. They are now required to teach in English. The purpose of this intrinsic case study was to describe the communicative dispositions of Afrikaans-speaking Foundation Phase teachers and to establish how the changing linguistic context of Ditlou Primary School may have influenced their communicative dispositions when teaching. This qualitative study is theoretically underpinned by McCroskey’s Model of Instructional Communication (2004) as a theoretical framework and used interpretivism as an epistemological paradigm. Data were collected through extensive field work. The instrumentation included a language-biography questionnaire, semi-structured and group interviews and a participant journal. The data collected were pooled categorised and coded (deductive and inductive). Although unique to each teacher-participant, key findings suggests that a generic communicative disposition could be sketched for Afrikaans-speaking Foundation Phase teachers at the research site. The teacher-participants agreed that they spoke at a much slower pace and that their voice pitch was higher than when they taught in their mother tongue. The volume of their speech also differed when using English for instructional purposes. Their oral proficiency in the language of teaching and learning could be considered sufficient. In terms of non-verbal communicative aspects, the layout of all classrooms was strictly traditional and authoritarian ensuring learner eye-contact constantly. Yet despite strict discipline, teachers prioritised the emotional well-being of their learners by displaying positive haptic and kinaesthetic behaviour. The influence of personality or temperament on their communicative disposition cannot be negated and is directly linked to their habitual behavioural patterns and unique traits exhibited in their classroom communication. The changed linguistic context primarily influenced the teacher-participants communicative dispositions by necessitating a switch to English as the medium of instruction - a language which is neither theirs nor the learners’ home language. Teaching multi-cultural and multi-lingual learners also had a direct bearing on how the teacher-participants communicative dispositions changed although this was self-reported and would need further investigation. Further recommendations emanating from this study include providing a framework to prepare pre-service teachers to teach in a non-native language and to help them develop effective communicative dispositions for the classroom.Dissertation (MEd)--University of Pretoria, 2017.
Humanities Education
MEd
Unrestricted
29
Silvestre, Navarro Francisco Miguel. "PENSADO A MANO, FABRICADO EN SERIE. Pioneros del Diseño Industrial. Transformación y adaptabilidad de las profesiones creativas." Doctoral thesis, Universitat Politècnica de València, 2016. http://hdl.handle.net/10251/62207.
Abstract:
[EN] The consolidation of the figure of the industrial designer in the United States during the middle decades of the twentieth century is the issue raised by this investigation. This process involves the transition between craft and industry that had begun centuries ago. American designers specialized in a new profession, they set up a shared, multidisciplinary intelligence. Perhaps unwittingly they pioneered in blurring the boundaries between the creative disciplines. It is a valuable model of transformation and adaptability that you can draw conclusions and parallels with the current period, an example with which to prepare and understand the acceleration produced by the third industrial revolution, and the changes produced in the creative professions.
There have always been more or less traditional way, ways to mass produce everything around us, from everyday objects to architectures. But it is the second industrial revolution, with the emergence of Taylorism and the Ford revolution, which by new machines and systematization of manufacturing processes introduced a turning point in this development.
Movements in Europe as the Arts and Crafts succeeded, groups and associations were established as the Wiener Werkstätte and the Bauhaus and later Werkbunds was established, all connected and that influenced in part on the evolution of design in the young American nation. The United States gave an exceptional context: a market coupled with unprecedented scale, a company with an innovative technical comfort in energy, materials and media led to a way of life, The American way of life, with its lights and shadows. It was just the right distance from the European tradition of the elements that favored the consolidation of the industrial design profession in US territory.
The historical uniqueness lies in the level of technical expertise had increased to make the knowledge to produce a well exceed the ability of a person. The pioneers of American design coordinated work of multidisciplinary teams of engineers, architects, manufacturers, advertisers... while accompanying the product until the communication process, encouraged by the needs of large companies. This allowed them to work in a variety of projects that did not happen so broadly notable examples from the Renaissance. They worked in fields such as graphic design, industrial design, interior design, architectural design, urban design, automotive design, railways, naval design, aircraft design... even aerospace design, creating new types and extending the scope of their work.
The most important designers of the period were Raymond Loewy, Norman Bel Geddes, Walter Dorwin Teague and Henry Dreyfuss, from the world of stage design, illustration and window dressing. Guided by intuition helped the beauty industry from the 1920s.
Speaking of the birth of industrial design assumes deepen relations between art and industry, between man and machine. It invites us to ask questions that make up what is to come.[ES] La consolidación de la figura del diseñador industrial en Estados Unidos durante las décadas centrales del siglo XX es el tema que suscita la presente investigación. Este proceso supone la transición entre artesanía e industria que había comenzado siglos atrás. Los diseñadores americanos se especializaron en una nueva profesión, pusieron en marcha una inteligencia compartida y multidisciplinar. Quizás sin saberlo fueron pioneros en desdibujar los límites entre las disciplinas creativas. Es un valioso modelo de transformación y adaptabilidad del que se pueden extraer conclusiones y paralelismos con la época actual, un ejemplo con el que poder preparar y entender la aceleración producida por la tercera revolución industrial, y los cambios que produce en las profesiones creativas. Siempre han existido, de forma más o menos artesanal, maneras para producir en serie todo lo que nos rodea, desde los objetos más cotidianos hasta las arquitecturas. Pero es la segunda revolución industrial, con la aparición del Taylorismo y la revolución Ford, la que mediante nuevas máquinas y la sistematización de los procesos de fabricación introducen un punto de inflexión en este avance. En Europa se sucedieron instituciones, escuelas y movimientos como las Arts and Crafts, se establecieron colectivos y asociaciones como los Wiener Werkstätte y las Werkbunds y posteriormente se constituyó la Bauhaus, conectados todos ellos y que influyeron en parte en la evolución del diseño en la joven nación norteamericana. En Estados Unidos se dio un contexto excepcional: un mercado unido con unas dimensiones sin precedentes, una sociedad con un confort técnico novedoso en energías, materiales y medios de comunicación dieron lugar a un modo de vida, The american way of life, con sus luces y sus sombras. Fue la distancia justa de la tradición europea uno de los elementos que favoreció la consolidación del Diseño Industrial como profesión en territorio norteamericano. La singularidad histórica radica en que el nivel de especialización técnica había aumentado hasta hacer que los conocimientos para producir un bien excedieran la capacidad de una persona. Los pioneros del diseño americano coordinaban el trabajo de equipos multidisciplinares formados por ingenieros, arquitectos, fabricantes, publicistas¿ a la vez que acompañaban al producto hasta el proceso de comunicación, animados por las necesidades de las grandes compañías. Esto les permitió trabajar en una variedad de proyectos que no sucedía de forma tan amplia desde los notables ejemplos del Renacimiento. Trabajaron en campos como el diseño gráfico, el diseño industrial, diseño de interiores, diseño arquitectónico, diseño urbanístico, diseño automovilístico, diseño de ferrocarriles, diseño naval, diseño aeronáutico¿ incluso diseño aeroespacial, generando nuevos tipos y ampliando el espectro de sus trabajos. Los diseñadores más relevantes de esta época fueron Raymond Loewy, Norman Bel Geddes, Walter Dorwin Teague y Henry Dreyfuss, procedentes del mundo de la escenografía, la ilustración y el escaparatismo. Guiados por la intuición de la belleza ayudaron a la industria a partir de la década de 1920. Hablar del nacimiento del Diseño industrial supone profundizar en las relaciones entre arte e industria, entre el hombre y la máquina. Nos invita a plantearnos preguntas que inventen lo que está por venir.
[CAT] La consolidació de la figura del dissenyador industrial als Estats Units durant les dècades centrals del segle XX és el tema que suscita la present investigació. Aquest procés suposa la transició entre artesania i indùstria que havia començat segles arrere. Els dissenyadors americans es van especialitzar en una nova professió, van posar en funcionament una intel¿ligència compartida i multidisciplinar. Tal vegada, sense saber-ho, van ser pioners en desdibuixar els límits entre les disciplines creatives. És un valuós model de transformació i adaptabilitat del que es poden extraure conclusions i paral¿lelismes amb l'època actual, un exemple amb el què poder preparar i entendre l'acel¿leració produïda per la tercera revolució industrial, i els canvis que produeix amb les professions creatives. Sempre han existit, de forma més o menys artesanal, maneres per a produïr en sèrie tot allò que ens envolta, des de els objectes més quotidians, fins a les arquitectures. Però és la segona revolució industrial, amb el sorgiment del taylorisme i la revolució Ford, la que, mitjançant noves màquines i la sistematització dels processos de fabricació, introdueixen un punt d'inflexió en aquest avançament. A Europa es van succeïr institucions, escoles i moviments com les Arts and Crafts, es van establir col¿lectius i associacions com els Wiener Werkstätte i les Werkbunds, i posteriorment es va constituir la Bauhaus, connectats tots ells i que van influir en part en la evolució del disseny a la jove nació nordamericana. Als Estats Units es va donar un context excepcional: un mercat unit amb unes dimensions sense precedents, una societat amb un comfort tècnic novedós en energies, materials i mitjans de comunicació van donar lloc a un estil de vida, The american way of life, amb les seues llums i les seues ombres. Va ser la distància justa de la tradició europea un dels elements que va afavorir la consolidació del Disseny Industrial com a professió en territori nordamericà. La singularitat històrica radica en què el nivell d'especialització tècnica havia augmentat fins a fer que els coneixements per a produïr un bé excediren la capacitat d'una persona. Els pioners del disseny americà coordinaven el treball d'equips multidisciplinars formats per enginyers, arquitectes, fabricants, publicistes¿ a la vegada què acompanyaven el producte fins al procés de comunicació, recolzats per les necessitats de les grans companyies. Allò els va permetre treballar en una varietat de projectes que no succeïa de forma tan ampla des dels notables exemples del Renaixement. Van treballar en camps com el disseny gràfic, el disseny industrial, disseny d'interiors, disseny arquitectònic, disseny urbanístic, disseny automovilístic, disseny de ferrocarrils, disseny naval, disseny aeronàutic¿ inclús disseny aeroespacial, generant nous tipus i ampliant l'espectre dels seus treballs. Els dissenyadors més destacats d'aquesta època van ser Raymond Loewy, Norman Bel Geddes, Walter Dorwin Teague i Henry Dreyfuss, procedents del món de l'escenografia, la il¿lustració i l'escaparatisme. Guiats per la intuició de la bellessa, van ajudar a la indùstria a partir de la dècada de 1920. Parlar del naixement del Disseny Industrial suposa aprofundir en les relacions entre art i indùstria, entre l'home i la màquina. Ens convida a plantejar-nos preguntes que inventen allò que està per vindre.
Silvestre Navarro, FM. (2016). PENSADO A MANO, FABRICADO EN SERIE. Pioneros del Diseño Industrial. Transformación y adaptabilidad de las profesiones creativas [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/62207
TESIS
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Calvo, Lance Marcos. "A Strategy for Multilingual Spoken Language Understanding Based on Graphs of Linguistic Units." Doctoral thesis, Universitat Politècnica de València, 2016. http://hdl.handle.net/10251/62407.
Abstract:
[EN] In this thesis, the problem of multilingual spoken language understanding is addressed using graphs to model and combine the different knowledge sources that take part in the understanding process. As a result of this work, a full multilingual spoken language understanding system has been developed, in which statistical models and graphs of linguistic units are used. One key feature of this system is its ability to combine and process multiple inputs provided by one or more sources such as speech recognizers or machine translators.
A graph-based monolingual spoken language understanding system was developed as a starting point. The input to this system is a set of sentences that is provided by one or more speech recognition systems. First, these sentences are combined by means of a grammatical inference algorithm in order to build a graph of words. Next, the graph of words is processed to construct a graph of concepts by using a dynamic programming algorithm that identifies the lexical structures that represent the different concepts of the task. Finally, the graph of concepts is used to build the best sequence of concepts.
The multilingual case happens when the user speaks a language different to the one natively supported by the system. In this thesis, a test-on-source approach was followed. This means that the input sentences are translated into the system's language, and then they are processed by the monolingual system. For this purpose, two speech translation systems were developed. The output of these speech translation systems are graphs of words that are then processed by the monolingual graph-based spoken language understanding system.
Both in the monolingual case and in the multilingual case, the experimental results show that a combination of several inputs allows to improve the results obtained with a single input. In fact, this approach outperforms the current state of the art in many cases when several inputs are combined.[ES] En esta tesis se aborda el problema de la comprensión multilingüe del habla utilizando grafos para modelizar y combinar las diversas fuentes de conocimiento que intervienen en el proceso. Como resultado se ha desarrollado un sistema completo de comprensión multilingüe que utiliza modelos estadísticos y grafos de unidades lingüísticas. El punto fuerte de este sistema es su capacidad para combinar y procesar múltiples entradas proporcionadas por una o varias fuentes, como reconocedores de habla o traductores automáticos. Como punto de partida se desarrolló un sistema de comprensión multilingüe basado en grafos. La entrada a este sistema es un conjunto de frases obtenido a partir de uno o varios reconocedores de habla. En primer lugar, se aplica un algoritmo de inferencia gramatical que combina estas frases y obtiene un grafo de palabras. A continuación, se analiza el grafo de palabras mediante un algoritmo de programación dinámica que identifica las estructuras léxicas correspondientes a los distintos conceptos de la tarea, de forma que se construye un grafo de conceptos. Finalmente, se procesa el grafo de conceptos para encontrar la mejo secuencia de conceptos. El caso multilingüe ocurre cuando el usuario habla una lengua distinta a la original del sistema. En este trabajo se ha utilizado una estrategia test-on-source, en la cual las frases de entrada se traducen al lenguaje del sistema y éste las trata de forma monolingüe. Para ello se han propuesto dos sistemas de traducción del habla cuya salida son grafos de palabras, los cuales son procesados por el algoritmo de comprensión basado en grafos. Tanto en la configuración monolingüe como en la multilingüe los resultados muestran que la combinación de varias entradas permite mejorar los resultados obtenidos con una sola entrada. De hecho, esta aproximación consigue en muchos casos mejores resultados que el actual estado del arte cuando se utiliza una combinación de varias entradas.
[CAT] Aquesta tesi tracta el problema de la comprensió multilingüe de la parla utilitzant grafs per a modelitzar i combinar les diverses fonts de coneixement que intervenen en el procés. Com a resultat s'ha desenvolupat un sistema complet de comprensió multilingüe de la parla que utilitza models estadístics i grafs d'unitats lingüístiques. El punt fort d'aquest sistema és la seua capacitat per combinar i processar múltiples entrades proporcionades per una o diverses fonts, com reconeixedors de la parla o traductors automàtics. Com a punt de partida, es va desenvolupar un sistema de comprensió monolingüe basat en grafs. L'entrada d'aquest sistema és un conjunt de frases obtingut a partir d'un o més reconeixedors de la parla. En primer lloc, s'aplica un algorisme d'inferència gramatical que combina aquestes frases i obté un graf de paraules. A continuació, s'analitza el graf de paraules mitjançant un algorisme de programació dinàmica que identifica les estructures lèxiques corresponents als distints conceptes de la tasca, de forma que es construeix un graf de conceptes. Finalment, es processa aquest graf de conceptes per trobar la millor seqüència de conceptes. El cas multilingüe ocorre quan l'usuari parla una llengua diferent a l'original del sistema. En aquest treball s'ha utilitzat una estratègia test-on-source, en la qual les frases d'entrada es tradueixen a la llengua del sistema, i aquest les tracta de forma monolingüe. Per a fer-ho es proposen dos sistemes de traducció de la parla l'eixida dels quals són grafs de paraules. Aquests grafs són posteriorment processats per l'algorisme de comprensió basat en grafs. Tant per la configuració monolingüe com per la multilingüe els resultats mostren que la combinació de diverses entrades és capaç de millorar el resultats obtinguts utilitzant una sola entrada. De fet, aquesta aproximació aconsegueix en molts casos millors resultats que l'actual estat de l'art quan s'utilitza una combinació de diverses entrades.
Calvo Lance, M. (2016). A Strategy for Multilingual Spoken Language Understanding Based on Graphs of Linguistic Units [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/62407
TESIS
31
Guimarães, Joana Alexandra Carvalho. "Patogénese da artrite idiopática juvenil sistémica. Papel da imunidade inata." Dissertação, Instituto de Ciências Biomédicas Abel Salazar, 2010. http://hdl.handle.net/10216/62307.
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Pereira, Cátia Marisa Loureiro. "A simulação como metodologia de aquisição de competências na formação médica pré-graduada." Dissertação, Instituto de Ciências Biomédicas Abel Salazar, 2010. http://hdl.handle.net/10216/62207.
33
Кожихова, К. В. "Синтез новых носителей лекарственных веществ на основе полисахаридов и фосфолипидов : диссертация на соискание ученой степени кандидата химических наук : 02.00.03." Thesis, б. и, 2018. http://hdl.handle.net/10995/62607.
34
Skrataas, Stine Mia Rømmesmo. "Compressible flows in process equipment: Problems, methods and models." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for energi- og prosessteknikk, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-13685.
Abstract:
SIMPLE, SIMPLER, SIMPLEC and IDEAL are solution procedures originally developed for incompressible flows and staggered grids. For SIMPLE, SIMPLER and SIMPLEC, extensions for collocated grids and for treatment of flows at all speeds have already been proposed. For IDEAL, only an extension for collocated grids has been found, and an extension for treatment of flows at all speeds is proposed here. Extended versions of SIMPLE and SIMPLER are implemented in Brilliant, a multiphysics CFD-program developed by Petrell AS. These implemented algorithms are compared to the existing solution procedure in Brilliant, an extended version of the SIMPLEC algorithm. As expected, SIMPLE and SIMPLEC gave almost identical solutions for all the three presented test cases. The values given by the SIMPLER algorithm differed slightly from the values given by the two other algorithms. When simulating a shock tube, all three algorithms showed large deviations from the quasi-analytical solution in some regions of the shock tube. The SIMPLER algorithm spent the least CPU time for this simulation example, while SIMPLE and SIMPLEC spent less CPU time than SIMPLER when simulating methane flow in a pipe. Even though the CPU time was not registered for the last simulation example, a pressure relief pipe, it was noticed that the time consumption was much greater for the SIMPLER algorithm than for SIMPLE and SIMPLEC.
35
Koch, Martin Andreas. "Development of in vitro and in vivo Bioreactors for Bone Tissue Engineering." Doctoral thesis, Universitat Politècnica de Catalunya, 2010. http://hdl.handle.net/10803/6207.
Abstract:
Grandes defectos óseos constituyen un reto para el campo clínico, ya que no puede ser reparado por el propio organismo, sino que requieren la implantación de injertos de hueso adecuado. Para superar los inconvenientes de los injertos procedentes de fuentes autólogas o allogeneicas, la ingeniería de tejidos óseos pretende sustituir el tejido perdido utilizando el cultivo de células in vitro sobre biomateriales porosos. El cultivo de células en grandes andamios porosos ha demostrado ser difícil, que requiere bioreactores, que se utilizan para el cultivo de tejidos y el estudio del comportamiento de células en 3D de los andamios. De interés especial es el condicionamiento mecánico de los tejidos cultivados por bioreactor de la ingeniería del tejido óseo, que es capaz de aumentar el potencial osteogénico de los injertos sintéticos.En este trabajo, dos sistemas de bioreactores fueron desarrollados para permitir comprender las propiedades bioactivas de andamios de diferentes materiales y la mecanoregulación del comportamiento de células o tejidos. Un sistema de bioreactor de perfusión in vitro fue desarrollado para el sembrado y cultivo de células incorporadas en cilindros de un biomaterial poroso. Varios estudios para la determinación de los parámetros del sembrado de células aplicable se llevaron a cabo, así como experimentos de cultivo de células bajo flujo de fluido constante con una estimulación mecánica adicional por alternancia del flujo.
Un sistema de cámara ósea fue desarrollado como un bioreactor in vivo. El sistema produjo un defecto óseo grande en tibias de perros y permitió la implantación repetida de grandes andamios porosos de materiales diferentes. El tejido creciendo en los andamios permite extraer conclusiones sobre las propiedades de osteoconductividad u osteinductividad de los andamios. Además, un dispositivo de compresión se ha desarrollado para aplicar cargas cíclicas en los andamios en vivo para estudiar el efecto de la estimulación mecánica en el desarrollo de los tejidos.
Los estudios con el sistema de perfusión desarrollado han demostrado que el sembrado de células en grandes andamios porosos es posible, lo que se considera crucial para el cultivo celular. El largo tiempo de cultivo de células mostró la proliferación de las células madre mesenquimales hasta dos semanas. El patrón de estimulación utilizado en el estudio aumentó la expresión de la osteocalcina, lo que indica una mayor actividad de las células, pero la ausencia de expresión de RunX2 y colágeno I impidió la determinación concluyente de la diferenciación.
El sistema desarrollado de la cámara ósea demostró su funcionalidad en el entorno quirúrgico durante los experimentos in vivo. Complicaciones durante los experimentos no permitieron la aplicación de las cargas cíclicas de los andamios implantados. La formación de hueso retrasada debido al defecto óseo creado y material de andamios restantes no permitieron conclusiones definitivas acerca de las propiedades del material del andamio. Sin embargo, el estudio proporciona datos para el desarrollo futuro del dispositivo y protocolo clínico.
Los estudios realizados constituyen una novedad en respecto a la creación de bioreactores para el estudio de la andamios porosos sintéticos de grandes dimensiones in vitro e in vivo. Los sistemas desarrollados constituyen la base para otros estudios en mecanobiología de las células óseas y los tejidos.
Large bone defects constitute a challenge for the clinical field, because they cannot be repaired by the body itself, but require the implantation of suitable bone grafts. To overcome the drawbacks of grafts from autologous or allogous sources, modern bone tissue engineering aims to replace lost tissue by cultivating cells in vitro on porous biomaterials. The cell culture on large porous scaffolds has shown to be difficult, requiring bioreactors, which are used for tissue culture and the study of cell behaviour in 3D scaffolds. Of special interest is the mechanical conditioning of the cultured tissue for bioreactor-based bone tissue engineering, which is able to enhance the osteogenic potential of the synthetic grafts.
In this work two bioreactor systems were developed to allow insight into bioactive properties of different scaffold materials and the mechanoregulation of cell or tissue behaviour. An in vitro perfusion bioreactor system was developed for the cell seeding and culture on porous biomaterial cylinders. Several studies for the determination of applicable cell seeding parameters were conducted, as well as experiments of cell culture under steady fluid flow with additional mechanical stimulation by alternating fluid flow. A bone chamber system was developed as an in vivo bioreactor. The system produced a large bone defect in dog tibia and allowed the repeated implantation of large porous scaffolds of different material compositions.
The ingrowing tissue was observed to allow conclusions about osteoconductive or osteinductive properties of the scaffolds. Additionally a compression device was developed to apply cyclic loading on the scaffolds in vivo to study the effect of mechanical stimulation on tissue development.
The studies with the developed in vitro perfusion bioreactor system have shown that it is possible to seed cells throughout large porous scaffolds, which is deemed crucial for the further cell culture. The long time cell culture showed the proliferation of mesenchymal stem cells up to two weeks. The stimulation pattern used in the study enhanced the expression of osteocalcin, indicating an enhanced cell activity, but the absence of RunX2 and collagen I expression rendered the determination of differentiation inconclusive.
The developed bone chamber system proved to be functional in the surgical environment during the in vivo experiments. Occurring complications during the experiments did not allow the application of the cyclic loading of implanted scaffolds. Delayed bone formation due to created bone defect and remaining scaffold material did not allow final conclusions about the scaffold material properties. Nevertheless the study provides input for further development of the device and clinical protocol.
The conducted studies constitute a novelty regarding the creation of bioreactors for the study of synthetic porous scaffolds of large dimensions in vitro and in vivo. The developed systems form the basis for further studies in mechanobiology of bone cells and tissue.
36
Kagaya, Mieko, Nayumi Iwata, Yasushi Toda, Takahiro Mitsui, Yasuyuki Nakae, and Takaharu Kondo. "Cold Milk Accelerates Oro-Cecal Transit Time During the Luteal Phasebut not the Follicular Phase in Women." 名古屋大学医学部, 1999. http://hdl.handle.net/2237/6207.
37
Cheung, Michael B. "Respiratory Syncytial Virus-infected Mesenchymal Stem Cells Regulate Immunity via Interferon-beta and Indoleamine-2,3-dioxygenase." Scholar Commons, 2016. http://scholarcommons.usf.edu/etd/6207.
Abstract:
Respiratory syncytial virus (RSV) is the most common cause of acute lower respiratory tract infection in young children worldwide, accounting for an estimated 33.8 million cases of respiratory disease, over 3 million of which require hospitalization, and between 66,000 and 199,000 deaths in this susceptible population. Additionally, severe RSV infection early in life is associated with an increased risk of wheeze and other airway disorders later in life. Despite this, there is currently no vaccine or economically reasonable prophylactic regimen to prevent infection. While disease is typically more severe in infancy RSV can infect throughout the lifespan repeatedly as the body does not develop protective immunity during primary or subsequent infection. The mechanisms behind this incomplete immunity are unclear.
RSV has been reported to infect numerous extra-epithelial cell types. Interestingly, viral infection in human mesenchymal stem cells (MSCs) has been reported, but the consequences are poorly understood. MSCs are an immune regulatory cell population present in nearly every organ including the nasal mucosa and the lung. They play a role in regulating immune responses and mediating tissue repair. In the following studies we sought to determine whether RSV infection of MSCs enhances their immune regulatory functions and contributes to RSV-associated lung disease.
RSV was shown to replicate in human MSCs by fluorescence microscopy, plaque assay, and expression of RSV transcripts. RSV-infected MSCs showed differentially altered expression of cytokines and chemokines such as IL-1β, IL-6, IL-8 and SDF-1 compared to normal human bronchial epithelial cells. Notably, RSV-infected MSCs exhibited significantly increased expression of IFN-β (~100-fold) and indoleamine-2,3-dioxygenase (IDO) (~70-fold) compared with mock-infected MSCs. IDO was identified in cytosolic protein of infected cells by Western blots and enzymatic activity was detected by tryptophan catabolism assay. Treatment of PBMCs with culture supernatants from RSV-infected MSCs reduced their proliferation in a dose dependent manner. This effect on PBMC activation was reversed by treatment of MSCs with the IDO inhibitors 1-methyltryptophan and vitamin K3 during RSV infection.
We also demonstrated the pathway leading to IDO expression in RSV infected MSCs. Neutralizing IFN-β prevented IDO expression and activity indicating its role as a viral response factor perhaps “high jacked” by the virus in immune escape. Treatment of MSCs with an endosomal TLR, but not a RIG-I, inhibitor prevented IFN-β and IDO expression. Additionally, TLR3/dsRNA complex inhibitor was able to block IFN-β stimulation, while a TLR7/8/9 inhibitory ODN did not, suggesting that endosomal TLR3 detection of RSV dsRNA was leading to IFN-β and IDO expression. Together, these findings indicate that RSV infection of MSCs triggers their immune regulatory function via TLR3 recognition of dsRNA, upregulating IFN-β expression and IDO activity, ultimately affecting immune cell proliferation. This finding may account for the lack of protective RSV immunity and consequent repeated infections throughout one's lifetime.
38
Desjardins, Steven J. "Image analysis in Fourier space." Thesis, University of Ottawa (Canada), 2002. http://hdl.handle.net/10393/6207.
Abstract:
General results on Fourier Transforms, tight frame wavelets and pseudodifferential operators are presented to provide a theoretical framework for the applications. Known and new tight frame wavelets that are characteristic and tapered characteristic functions in Fourier Space are constructed in Cartesian and polar Fourier Space with frame bound 1. These wavelets are used to localize singularities in images. A review of the use of the diffusion equation in de-noising images is presented. A new method, which applies a multi-directional diffusion in Fourier Space is given. Properties of this new product filter method are described and the product filter's de-noising ability is evaluated. The product filter algorithm is also compared to other techniques, including MATLAB's built-in filters and two recent wavelet techniques. Finally, a summary of the results of a study of the de-noising abilities of third-order partial differential equations is presented.
39
Farner, William Robert. "On-chip probe metrology /." Online version of thesis, 2008. http://hdl.handle.net/1850/6207.
40
Wang, Chao. "The relationship between traffic congestion and road accidents : an econometric approach using GIS." Thesis, Loughborough University, 2010. https://dspace.lboro.ac.uk/2134/6207.
Abstract:
Both traffic congestion and road accidents impose a burden on society, and it is therefore important for transport policy makers to reduce their impact. An ideal scenario would be that traffic congestion and accidents are reduced simultaneously, however, this may not be possible since it has been speculated that increased traffic congestion may be beneficial in terms of road safety. This is based on the premise that there would be fewer fatal accidents and the accidents that occurred would tend to be less severe due to the low average speed when congestion is present. If this is confirmed then it poses a potential dilemma for transport policy makers: the benefit of reducing congestion might be off-set by more severe accidents. It is therefore important to fully understand the relationship between traffic congestion and road accidents while controlling for other factors affecting road traffic accidents. The relationship between traffic congestion and road accidents appears to be an under researched area. Previous studies often lack a suitable congestion measurement and an appropriate econometric model using real-world data. This thesis aims to explore the relationship between traffic congestion and road accidents by using an econometric and GIS approach. The analysis is based on the data from the M25 motorway and its surrounding major roads for the period 2003-2007. A series of econometric models have been employed to investigate the effect of traffic congestion on both accident frequency (such as classical Negative Binomial and Bayesian spatial models) and accident severity (such as ordered logit and mixed logit models). The Bayesian spatial model and the mixed logit model are the best models estimated for accident frequency and accident severity analyses respectively. The model estimation results suggest that traffic congestion is positively associated with the frequency of fatal and serious injury accidents and negatively (i.e. inversely) associated with the severity of accidents that have occurred. Traffic congestion is found to have little impact on the frequency of slight injury accidents. Other contributing factors have also been controlled for and produced results consistent with previous studies. It is concluded that traffic congestion overall has a negative impact on road safety. This may be partially due to higher speed variance among vehicles within and between lanes and erratic driving behaviour in the presence of congestion. The results indicate that mobility and safety can be improved simultaneously, and therefore there is significant additional benefit of reducing traffic congestion in terms of road safety. Several policy implications have been identified in order to optimise the traffic flow and improve driving behaviour, which would be beneficial to both congestion and accident reduction. This includes: reinforcing electronic warning signs and the Active Traffic Management, enforcing average speed on a stretch of a roadway and introducing minimum speed limits in the UK. This thesis contributes to knowledge in terms of the relationship between traffic congestion and road accidents, showing that mobility and safety can be improved simultaneously. A new hypothesis is proposed that traffic congestion on major roads may increase the occurrence of serious injury accidents. This thesis also proposes a new map-matching technique so as to assign accidents to the correct road segments, and shows how a two-stage modelling process which combines both accident frequency and severity models can be used in site ranking with the objective of identifying hazardous accident hotspots for further safety examination and treatment.
41
Imhof, Ingrid. "Development of an intra- and intergenotypic HCV cell culture method to phenotype and assess antiviral susceptibilities and resistance development of HCV NS3 protease genes from HCV genotypes 1-6." Thesis, University of Edinburgh, 2010. http://hdl.handle.net/1842/6207.
Abstract:
The development of specific antiviral drugs directly targeting the hepatitis C virus (HCV) is clinically important, as the current standard interferon/ribavirin combination treatment is only partially effective, expensive and often associated with severe side effects. Inhibitors of the NS3 protease (PI) therefore represent a promising alternative or additional therapy. To date, the development and in vitro evaluation of PIs is restricted to the genotype 1/2 based replicon and the genotype 2a full length viral cell culture system. However, proteases of the different HCV genotypes vary substantially in their amino acid sequence and secondary structure and require separate evaluation of their efficacy before they go into clinical trials. To address this issue, a panel of intra- and intergenotypic recombinants based on the recombinant infectious clone Jc1 (pFK JFH1/J6/C-846) was developed in this work. The viability of these recombinants was assessed in the Huh7.5 cell culture system, where replicating viruses were detected by HCV-NS5A immunostaining. Intergenotypic recombinants containing genotype 1a, 1b, 3a, 4a and 6a derived proteases were replication defective, whereas the recombinant with genotype 5a derived protease replicated efficiently after acquiring cell culture adaptive mutations. The replacement of not only the NS3 protease gene region, but also its cofactor NS4A, allowed the generation of replication competent intra- and intergenotypic recombinants for all 6 major genotypes. Replacing the NS3 protease of the recombinants with that of patientderived proteases also generated replicating recombinants, greatly expanding the panel of intergenotypic recombinants available for phenotyping and PI evaluation. However, intra- and intergenotypic recombinants showed substantial differences in their replication kinetics, which may be influenced by naturally occurring polymorphism between genotypes and the differential requirement of adaptive/attenuating cell culture mutations. Genotype 1a recombinants replicated very poorly, which may be due to incompatibilities between the type 1a NS3/4A protease and the type 2a backbone. 50% inhibitory concentrations (IC50) of different PIs were measured using Foci Forming Units/ml (FFU/ml) reductions and replication inhibition assays. The different recombinants showed consistent, genotype-associated differences in their susceptibility to the PI BILN 2061, with genotypes 2a, 3a and 5a derived recombinants showing approximately 100-fold lower susceptibility than genotype 1b, 4a and 6a derived recombinants. These observations are consistent with major differences in response rates found in recent treatment trials of genotype 1, 2 and 3 infected patients. Differences in susceptibility were also observed for VX-950, with genotype 1b, 2a and 6a derived recombinants being twice as susceptible than genotype 3a, 4a and 5a derived recombinants. Passaging the intra- and intergenotypic recombinants under increasing concentrations of PI allowed the identification of PI resistance mutations. Resistance mutations to BILN 2061 mapped to the previously identified positions 156 and 168 within the NS3 protease, with a great diversity of amino acid substitutions observed within each genotype. Reintroduction of the identified resistance mutations into the original recombinant viruses conferred increased resistance towards BILN 2061 and some mutations also affected replication kinetics of the recombinants. The developed system will be of major value for the phenotypic characterisation of naturally occurring and treatment induced resistance mutations within all 6 major HCV genotypes towards different PIs. This will allow treatment response predictions for newly developed PIs before they enter clinical trials and the development of individually tailored antiviral treatment regimes.
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Morton, Amba Jessida. "Invisible Episteme - The Mirrors and String of Modernity." Thesis, University of Canterbury. Social and Political Sciences, 2011. http://hdl.handle.net/10092/6207.
Abstract:
This thesis is an interrogation into the epistemological structures which underpin modernity, the project and claim which has come to significantly shape the contemporary world. Following a line of inquiry which analyses the intersections between knowledge, power, and history, this paper examines how signifiers such as religion and culture have come to designate ‘otherness’ in the context of modernity. The assignment of such terms to beliefs, values, worldviews, and ideologies that are not readily assimilated by the epistemological framework of modernity is problematised as a central obstacle to mediating social and political difficulties in modern contexts.
The argument is that the issue of ‘what counts for knowledge’ has been progressively ‘closed’ through particular historical processes in which the shift from a societal model based upon Judeo-Christian tenets, to secular modernity, has been rendered invisible. The ‘other’ has, through these processes, become twice-removed from epistemological validity: in the first instance, as the ‘pagan’ other in early Christian contexts; in the second instance, as the ‘religious’ or ‘cultural’ other within a secular that is falsely claimed to have been liberated from its theological roots. These epistemological marginalisations impact significantly on social life, especially in the areas of education and medicine.
The invisibility of the shift from Christianity to secular modernity is also perpetuated by the separation of social life and knowledge production into distinct ‘spheres’, as mirrored by the arrangement of disciplinary spheres established within the modern universities. The conclusion is that a transdisciplinary space is therefore required to engage philosophically and critically with the now internalised Christian bias of modernity.
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Richard, Jean-Philippe. "Fabrication de transistors monoélectroniques pour la détection de charge." Mémoire, Université de Sherbrooke, 2013. http://hdl.handle.net/11143/6207.
Abstract:
Le transistor monoélectronique (SET) est un candidat que l'on croyait avoir la capacité de remplacer le transistor des circuits intégrés actuel (MOSFET). Pour des raisons de faible gain en voltage, d'impédance de sortie élevée et de sensibilité aux fluctuations de charges, il est considéré aujourd'hui qu'un hybride tirant profit des deux technologies est plus avantageux. En exploitant sa lacune d'être sensible aux variations de charge, le SET est davantage utilisé dans des applications où la détection de charge s'avère indispensable, notamment dans les domaines de la bio-détection et de l'informatique quantique. Ce mémoire présente une étude du transistor monoélectronique utilisé en tant que détecteur de charge. La méthode de fabrication est basée sur le procédé nanodamascène développé par Dubuc et al. [11] permettant au transistor monoélectronique de fonctionner à température ambiante. La température d'opération étant intimement liée à la géométrie du SET, la clé du procédé nanodamascène réside dans le polissage chimico-mécanique (CMP) permettant de réduire l'épaisseur des SET jusqu'à des valeurs de quelques nanamètres. Dans ce projet de maîtrise, nous avons cependant opté pour que le SET soit opéré à température cryogénique. Une faible température d'opération permet le relâchement des contraintes de dimensions des dispositifs. En considérant les variations de procédés normales pouvant survenir lors de la fabrication, la température d'opération maximale calculée en conception s'étend de 27 K à 90 K, soit une énergie de charge de 78 meV à 23 meV. Le gain du détecteur de charge étant dépendant de la distance de couplage, les résultats de simulations démontrent que cette distance doit être de 200 nm pour que la détection de charge soit optimale. Les designs conçus sont ensuite fabriqués sur substrat d'oxyde de silicium. Les résultats de fabrication de SET témoignent de la robustesse du procédé nanodamascène. En effet, les dimensions atteintes expérimentalement s'avèrent quasi identiques à celles calculées en conception. Les mesures électriques à basse température de SET fabriqués démontrent un blocage de Coulomb avec une énergie de charge de 10 meV et une température d'opération maximale de 10 K. Un effet de grille est aussi observé par l'application d'une tension sur la grille latérale et les électrodes d'un SET à proximité. Les paramètres extraits à partir du diamant de Coulomb sont en accord avec les géométries du transistor fabriqué, à l'exception de la capacité degrille et de couplage. Enfin, l'étude de la détection de charge est réalisée par simulation à partir de ces paramètres. Elle permet de conclure que la détection de charge peut être optimisée en augmentant les surfaces de couplage de l'électromètre.
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Ribeiro, Ana Margarida de Bastos. "Approach, management and prediction of prognosis in the acute abdomen syndrome in dogs. Study of prognosis predictors in 28 cases." Master's thesis, Universidade de Lisboa. Faculdade de Medicina Veterinária, 2013. http://hdl.handle.net/10400.5/6207.
Abstract:
Dissertação de Mestrado Integrado em Medicina VeterináriaThe acute abdomen syndrome is characterized by an acute onset of abdominal pain, usually associated with general signs such as vomiting, diarrhoea, postural and gait changes, anorexia, lethargy and shock. Success results from a proactive approach to management, including rapid stabilization of major body systems, early identification of the inciting problem(s), attention to comorbid conditions, and timely definitive therapy. Herewith comes decision making, whether to take a patient to surgery or manage the patient medically. A thorough and systematic approach requires the use of diagnostic imaging modalities, including radiology and ultrasonography, performing diagnostic peritoneal lavage or abdominal paracentesis techniques, and blood work evaluation, including complete blood count and biochemistry profiles. In some cases, the results of diagnostic tests may lead to surgical versus medical management, particularly when a patient fails to respond to medical management alone. In other cases, rapid surgical management is necessary for patient survival. Also it must take into account the capabilities and equipment of the clinic, as well as the staff skills. This may be extremely effortful, time-consuming and expensive so the owners must be informed about the prognosis for survival as they frequently face the dilemma of euthanasia. In an attempt to make more valid prognostic assessment in cases of acute abdomen syndrome, many individual predictive factors and univariable analysis where investigated. A retrospective study was carried out on 28 dogs presented with acute abdomen. Medical records were reviewed and information regarding dog signalment, history, clinical and laboratory data, surgical findings and outcome was collected. After analysis, several easily measurable parameters were found to be outcome predictors in dogs with acute abdomen, these being creatinine and alkaline phosphatase values, skin tent evaluation and dehydration.
RESUMO - ABORDAGEM, MANEIO E PREVISÃO DE PROGNÓSTICO NA SÍNDROME DE ABDÓMEN AGUDO EM CÃES. ESTUDO DE PREVISORES DE PROGNÓSTICO EM 28 CASOS - A síndrome de abdómen agudo é caracterizada por dor abdominal de início repentino, normalmente associada a sinais clínicos gerais tais como vómito, diarreia, alterações de postura e equilíbrio, anorexia, letargia e choque. O sucesso na resolução desta síndrome resulta de uma abordagem proactiva ao maneio médico, incluindo estabilização rápida dos sistemas vitais, rápida identificação, atenção a situações concomitantes e terapia definitiva realizada atempadamente. Posto isto, a decisão de submeter o paciente a cirurgia ou de o tratar conservativamente tem de ser tomada. Uma abordagem completa e sistemática passa pela imagiologia, incluindo raio-x e ecografia, lavagem peritoneal diagnóstica ou abdominocentese, e análises sanguíneas, incluindo hemograma e bioquímicas. Por vezes, os resultados dos testes diagnósticos podem levar ao maneio médico versus o cirúrgico, especialmente quando não há resposta à terapêutica conservativa por parte do paciente. Noutros casos, o maneio cirúrgico urgente é necessário para a sobrevivência do doente. É também necessário ter em consideração as capacidades e equipamento do centro de atendimento médico veterinário, bem como as competências dos veterinários responsáveis. Isto pode ser extremamente trabalhoso, demorado e caro para os proprietários, devendo estes ser informados acerca do prognóstico, visto que muitas das vezes deparam-se com o dilema da eutanásia. Na tentativa de tornar a avaliação prognóstica mais eficaz na síndrome de abdómen agudo, foram avaliados previsores individuais de prognóstico e realizada a respetiva análise univariada. Foi realizado um estudo retrospectivo em 28 cães que se apresentaram com abdómen agudo. A anamnese foi feita e a informação sobre os sinais clínicos, os dados do exame físico e laboratoriais, os achados das cirurgias e prognóstico foram colhidos. Após análise, alguns parâmetros facilmente mensuráveis, mostraram contribuir para a previsão do prognóstico em cães com abdómen agudo, sendo estes os valores de creatinina e fosfatase alcalina, a avaliação da prega de pele e a desidratação do animal.
45
Salomón, Ana Carolina. "Situación socio-demográficas y de salud de niños de 0 a 5 años de muertes maternas ocurridas en el Hosptial Regional "Dr. Ramón Carrillo. Santiago del Estero, año 2008." Doctoral thesis, Salomón AC. Situación socio-demográficas y de salud de niños de 0 a 5 años de muertes maternas ocurridas en el Hosptial Regional "Dr. Ramón Carrillo. Santiago del Estero, año 2008 [Internet]. Universidad Nacional de Córdoba; 2016 [citado el 13 de febrero de 2020]. Disponible en: https://rdu.unc.edu.ar/handle/11086/6207, 2016. http://hdl.handle.net/11086/6207.
Abstract:
Tesis - Doctor en Medicina y Cirugía - Universidad Nacional de Córdoba. Facultad de Ciencias Médicas, 2016219 h. : il., gráf.; 29 cm.
Foundation: The population Santiago del Estero presented obstacies geographical, economic, social, communicational and cultural that hindered to them women in process reproductive receive attention of health adequate and timely; dying arbitrarily, leaving children orphaned and families caregivers, many times in situations adverse and very unfavorable. Population and sample: Total (16) records included maternal deaths that occurred at the hospital of reference year 2008; 7 surviving orphans under age 5 who are kept in the family. Controls: 14 mothers living; 14 children under 5 years, through stratified random sampling.
Fundamentación: La población santiagueña presentó obstáculos geográficos, económicos, sociales, comunicacionales y culturales que dificultaron a las mujeres en proceso reproductivo recibir atención de salud adecuada y oportuna; muriendo arbitrariamente, dejando hijos huérfanos y familiares cuidadoras, muchas veces en situaciones adversas y muy desfavorables. Diseño: Estudio descriptivo-prospectivo, transversal y observacional. Población y muestra: Se incluyeron los registros del total (16) de las muertes maternas ocurridas en el Hospital de referencia, años 2008: 7 huérfanos sobrevivientes menores de 5 años que se mantenían en el núcleo familiar. Controles 14 madres vivas; 14 menores de 5 años, mediante muestreo aleatorio estratificado
|Fil: De Salomón, Ana Carolina. Universidad Nacional de Córdoba. Facultad de Ciencias Médicas; Argentina.
46
Schmidt, Urdanivia Johannes. "El sistema de gestión de calidad basado en la norma ISO 9001:2008 y su influencia en el nivel de satisfacción de los psicólogos habilitados del Colegio de Psicólogos del Perú CDR I – Lima." Bachelor's thesis, Universidad Nacional Mayor de San Marcos, 2017. https://hdl.handle.net/20.500.12672/6207.
Abstract:
Describe el sistema de gestión de calidad basado en la norma ISO 9001:2008 implementado durante el periodo 2012 - 2014 en el Colegio de Psicólogos del Perú del Consejo Directivo Regional I – Lima. Determina si la mejora de los procesos de atención en cuanto a los elementos tangibles, fiabilidad, capacidad de respuesta, seguridad y empatía influye en el aumento de los niveles de satisfacción de los psicólogos habilitados. Es una investigación descriptiva, correlaciona, explicativa, prspectiva y longitudinal. Utiliza una muestra probabilística simple de 306 participantes a quienes aplica el cuestionario del Modelo Servqual de Calidad de Servicio. Encuentra que la implementación del sistema de gestión de calidad influye favorablemente en el nivel de satisfacción de los psicólogos habilitados.Tesis
47
Erckie, Laimi Nelago Koskima. "Impacts and control of alien Proteaceae invasion in the Western Cape Province, South Africa." University of the Western Cape, 2017. http://hdl.handle.net/11394/6207.
Abstract:
Magister Scientiae (Biodiversity and Conservation Biology) - MSc (Biodiv & Cons Biol)Research focused on ecological impacts and control of invasive alien species (IAS) is gaining attention worldwide. The eradication and control of invasive alien plants (IAP) is essential for the restoration of native plant communities. Understanding ecological impacts and potential invasive risks of IAP is important for their effective management, particularly for prioritisation. Most studies concerning impacts on vegetation structure and plant-pollinator interactions have measured few ecological metrics, resulting in a superficial understanding of plant species invasion. Additionally, most studies related to the control of IAP have focused on major invaders which have demonstrated severe impacts, with less focus on emerging invaders. This study assessed ecological impacts, invasive risks and chemical control options for alien Hakea drupacea and Banksia species in the Western Cape Province, South Africa. Multiple ecological metrics data on vegetation, soil and plant-pollinator parameters were measured and compared between invaded and uninvaded sites. The invasion risk of fourteen Banksia species which have been introduced to South Africa was evaluated by conducting a weed risk assessment (WRA). The herbicide efficacy of resprouting Banksia integrifolia and Banksia serrata was determined by rating plants response to different treatments, with percentage, height and resprout vigour as measures. Results revealed significant negative impacts of alien H. drupacea and Banksia speciosa invasion on native plant species richness and diversity and on the abundance of native pollinators. The study demonstrated that 79% of Banksia species have a high risk of invading the Fynbos Biome. Chemical control with triclopyr+picloram mix provided effective means of controlling resprouting Banksia species. The high invasive risk of Banksia species and competitive effects of invasive alien B. speciosa and H. drupacea with native plant species for biotic and abiotic resources represents a major threat to biodiversity conservation in the Fynbos Biome. The removal of both naturalised and invasive alien H. drupacea and Banksia populations is recommended in order to conserve native plant communities in the Fynbos Biome.
2020-08-31
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Silva, Muñoz Lydia. "Ontology-based metadata for e-learning content." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2004. http://hdl.handle.net/10183/6207.
Abstract:
Atualmente a popularidade da Web incentiva o desenvolvimento de sistemas hipermídia dedicados ao ensino a distância. Não obstante a maior parte destes sistemas usa os mesmos recursos do ensino tradicional, apresentado o conteúdo como páginas HTML estáticas, não fazendo uso das novas tecnologias que a Web oferece. Um desafío atual é desenvolver sistemas educativos que adaptem seu conteúdo ao estilo de aprendizagem, contexto e nível de conhecimento de cada aluno. Outro assunto de pesquisa é a capacidade de interoperar na Web reutilizando objetos de ensino. Este trabalho apresenta um enfoque que trata esses dois assuntos com as tecnologias da Web Semântica. O trabalho aqui apresentado modela o conhecimento do conteúdo educativo e do perfil do aluno pelo uso de ontologias cujo vocabulário é um refinamento de vocabulários padrões existentes na Web como pontos de referência para apoiar a interoperabilidade semântica. As ontologias permitem a representação numa linguagem formal dos metadados relativos a objetos de ensino simples e das regras que definem suas possíveis formas de agrupamento para desenvolver objetos mais complexos. Estes objetos mais complexos podem ser projetados para se adequar ao perfil de cada aluno por agentes inteligentes que usam a ontologia como origem de suas crenças. A reutilização de objetos de ensino entre diferentes aplicações é viabilizada pela construção de um perfil de aplicação do padrão IEEE LOM-Learning Object Metadata.Nowadays, the popularity of the Web encourages the development of Hypermedia Systems dedicated to e-learning. Nevertheless, most of the available Web teaching systems apply the traditional paper-based learning resources presented as HTML pages making no use of the new capabilities provided by the Web. There is a challenge to develop educative systems that adapt the educative content to the style of learning, context and background of each student. Another research issue is the capacity to interoperate on the Web reusing learning objects. This work presents an approach to address these two issues by using the technologies of the Semantic Web. The approach presented here models the knowledge of the educative content and the learner’s profile with ontologies whose vocabularies are a refinement of those defined on standards situated on the Web as reference points to provide semantics. Ontologies enable the representation of metadata concerning simple learning objects and the rules that define the way that they can feasibly be assembled to configure more complex ones. These complex learning objects could be created dynamically according to the learners’ profile by intelligent agents that use the ontologies as the source of their beliefs. Interoperability issues were addressed by using an application profile of the IEEE LOM- Learning Object Metadata standard.
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Івановський, М. Б., and Назарій Євгенович Бурак. "Особливості динаміки розвитку сфери ІТ в Україні." Thesis, Львівський державний університет безпеки життєдіяльності, 2019. http://hdl.handle.net/123456789/6207.
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Thomas, Theopolina. "Marama bean (Tylosema esculentum), a non-nodulating high protein legume indigenous to the Kalahari sands : studies of its N nutrition." Master's thesis, University of Cape Town, 2004. http://hdl.handle.net/11427/6207.
Abstract:
Includes bibliographical references (leaves 90-102)Marama bean is a non-nodulating perennial legume native to the nutrient-poor soils of the Kalahari Sands. In Botswana and Namibia, it is the staple food of the Khoisan people. Marama bean, however, still have not been cultivated or established as an agricultural crop in these countries. This study investigated soil factors affecting the distribution and growth of marama bean in the field and how it would respond to additional N and P supply both under field and glasshouse conditions. The study then attempts to explore and understand the mechanisms employed by marama bean to acquire high nutrient concentration in its organs.