Tesis: "Stratification"

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Lim, Huay Huay. "Period traveling salesman with customer stratification." Diss., Columbia, Mo. : University of Missouri-Columbia, 2006. http://hdl.handle.net/10355/5857.

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Thesis (Ph. D.)--University of Missouri-Columbia, 2006. The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on August 10, 2007) Vita. Includes bibliographical references.

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8

Caulfield, C. P. "Stratification and buoyancy in geophysical flows." Thesis, University of Cambridge, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386925.

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9

Li, Hei Philip, and 李曦. "Subphenotype stratification in systemic lupus erythematosus." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hub.hku.hk/bib/B48334765.

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Subsets of systemic lupus erythematosus (SLE) patients with distinct patterns of disease manifestations and autoantibody production have been reported, but seldom have these two phenomena been analysed together. Cluster analysis was performed on 1928 Chinese SLE patients based on autoantibody profile and the frequencies of various clinical manifestations were compared between each cluster. Separate association analyses between individual autoantibodies and clinical manifestations, as well as between clinical manifestations, were also performed. This study identifies three separate autoantibody clusters each with different clinical manifestations, and proposes that the phenomena of autoantibody clustering and clinical subsets may be inter-related. Patient clusters could also be stratified into a bipolar spectrum. On one end are patients with over-representation of anti-dsDNA and renal disorder; whilst on the other end are two distinct autoantibody clusters (anti-Sm/anti-RNP/aPL and aPL/anti-Ro/anti-La) with overlapping of other non-renal manifestations. Patient stratification could aid disease prediction and subsequent management. These findings may also elucidate disease pathogenesis and guide future study on potential common pathological processes within autoantibody clusters. published_or_final_version Paediatrics and Adolescent Medicine Master Master of Research in Medicine

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10

Boxall, S. R. "Thermohaline stratification in the Tyrrhenian Sea." Thesis, University of Liverpool, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.370837.

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11

Al-Khawaja, Imad Mahmoud Shihadeh. "Noninvasive risk stratification after myocardial infarction." Thesis, University of Surrey, 1988. http://epubs.surrey.ac.uk/847183/.

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In order to identify patients with severe coronary artery disease (CAD) and at a higher risk of future cardiac events after uncomplicated myocardial infarction, 105 consecutive patients were studied prospectively. There were 93 men and 12 women with a mean age of 56 +/- 8.2 years. Treadmill testing, exercise radionuclide ventriculography, thallium-201 myocardial imaging and selective coronary arteriography were performed 6-8 weeks after infarction. Patients were grouped into those who had single and multiple vessel disease. Multiple regression analysis of 18 noninvasive indices was carried out using generalized linear interactive modelling (GLIM) and the results were compared with the severity of underlying CAD and the clinical outcome after a mean follow-up period of 18.8 +/- 3. 4 months. At the end of the follow-up period, patients were categorized into those who had no cardiac events, minor and major cardiac events. Multivariate analysis produced an algorithm from three factors found to be most predictive of the severity of CAD. These included ST-segment depression on exercise, total score of rest and exercise regional wall motion and the presence of significant redistribution on thallium-201 imaging. The sensitivity of this algorithm for predicting multiple vessel disease was 42%, with a specificity of 94%, and a predictive accuracy of 69%. However, the total score of regional wall motion abnormalities was the single most predictive factor of major cardiac events with a sensitivity of 94%, a specificity of 57%, and predictive accuracy of 63%. None of the other factors produced additional prognostic information. Therefore, exercise radionuclide ventriculography appears to be the investigation of choice in assessing prognosis after myocardial infarction.

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12

Shalhoub, Joseph. "Risk stratification in atherosclerotic cartoid stenosis." Thesis, Imperial College London, 2011. http://hdl.handle.net/10044/1/9063.

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Introduction: Key trials and a Cochrane systematic review in asymptomatic carotid stenosis have highlighted the need to identify a high-risk subgroup of patients with carotid stenosis who may benefit from intervention. Traditionally, this risk stratification has considered structural imaging and clinical factors. However, using only these approaches, still a significant number of patients are missed. Biological attributes are acknowledged as key determinants of thrombo-embolic events. Functional and hybrid structural-functional imaging, and circulating biomarkers allow exploration of plaque biology non-invasively, in vivo. The importance of innate immunity in atherosclerosis is now established, with a recent interest in macrophage phenotypic polarisation in atherosclerosis supported by in vitro and experimental data, with the hypothesis of an M1 macrophage predominance associated with unstable plaques. The emergence of systems biology has been seen to facilitate understanding of biological pathways and generate hypotheses, although the utility of this approach for the examination of human atherosclerosis tissue has not been fully explored. Aims: (i) To employ functional imaging to probe carotid atherosclerosis in vivo; (ii) to assess the plaque microenvironment in determination of the balance of macrophage populations in unstable compared with stable atherosclerosis; (iii) to investigate whether late phase (LP-) contrast enhanced ultrasound (CEUS) reflects plaque biological features; (iv) to examine the utility of systems biology techniques in distinguishing symptomatic from asymptomatic carotid atherosclerosis tissue, and in hypothesis generation; and (v) to evaluate a putative biomarker for carotid atherosclerosis and plaque vulnerability. Methods: Patients with carotid stenosis, both symptomatic and asymptomatic, have undergone systematic collection of data, fresh carotid endarterectomy (CEA) specimens, and plasma. Thirty-two patients with 36 carotid stenoses underwent 11C-PK11195 PET/CT. Thirty-seven patients had dynamic (D-) and LP-CEUS carotid imaging. CEA specimens were assessed by immunohistochemical techniques, as well as atheroma cell culture with supernatant multi-analyte profiling (MAP). MAP data was subject to Ingenuity Pathway Analysis. CEA specimens were further examined using systems biology methodologies: transcriptomics with Affymetrix Human Exon 1.0 ST arrays; proteomics and lipidomics by liquid chromatography (LC) coupled to tandem triple quadrupole mass spectrometry (MS); and metabolite profiling by nuclear magnetic resonance and LC-MS. Furthermore, venous and arterial plasma was quantified for the lysozyme, a putative biomarker in carotid atherosclerosis. Results: 11C-PK11195 PET allowed the non-invasive quantification of intraplaque inflammation in patients with carotid stenoses and, when combined with CTA, provided an integrated assessment of plaque structure, composition and biological activity. 11C-PK11195 PET/CT distinguished between recently symptomatic vulnerable plaques and asymptomatic plaques with a high positive predictive value. D-CEUS and LP-CEUS (at a cut-off of zero) was able to distinguish symptomatic and asymptomatic plaques. Atheroma cell culture and supernatant MAP revealed that symptomatic human atherosclerotic carotid disease is associated with a cytokine and chemokine pattern consistent with the predominance of pro-inflammatory M1-type macrophage polarisation. Furthermore, IFNγ signatures are observed, including the novel finding of CCL20 with its significant elevation in symptomatic atherosclerosis. MAP of supernatants from patients who had undergone ipsilateral carotid LP-CEUS revealed significantly higher levels of IL6, MMP1 and MMP3, as well as greater CD68 and CD31 immunopositivity, in those with high (≥0) compared with low (<0) LP-CEUS signal. This suggests that LP-CEUS was able to reflect plaque biology. Transcriptomic analysis was able to clearly separate stenosing plaque and intimal thickening, as well as unstable and stable atherosclerosis, finding differential expression and alternative splicing of interferon regulatory factor 5 between stenosing plaque and intimal thickening. Proteomic analysis of the salt extract fraction from carotid atherosclerotic plaques identified 2,470 proteins implicated in 33 bio-molecular functions and having their origins previously described in 14 different cellular compartments. There were 159 proteins which, based upon the number of assigned spectra, were significantly different between symptomatic and asymptomatic atherosclerosis. Through lipidomic analysis, 150 lipid species from 9 different classes were identified, of which 24 were exclusive to atherosclerotic plaques. A comparison of 28 carotid endarterectomy specimens revealed differential lipid signatures of symptomatic compared with asymptomatic lesions, as well as stable and unstable plaque areas. Similarly, LC-MS metabolite profiling of organic plaque extract was able to separate symptomatic from asymptomatic atherosclerosis. Arterial and venous plasma lysozyme levels were seen to distinguish individuals with carotid atherosclerosis from matched control subjects. Furthermore, arterial plasma lysozyme levels were significantly higher in patients with symptomatic than asymptomatic carotid stenosis. Conclusions: These findings support the use of hybrid structural-functional imaging, and the utility and use of a systems biology approach in identifying significantly different and biologically relevant variations in atherosclerosis tissue, and in hypothesis generation for further study. The data presented concurs with recent reports in the literature linking the lipidic/organic component of atherosclerosis with the generation of a pro-inflammatory plaque microenvironment prone to lesion development, instability and the complications thereof. The importance of innate immunity has been highlighted with the demonstration of a predominance of M1 macrophage polarisation and evidence of Th17/IL17 signalling in unstable atherosclerosis. It is hoped that this work will contribute to the ongoing refinement of multi-factorial risk stratification in carotid atherosclerosis.

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13

Brainerd, Keith. "Upper ocean turbulence, mixing, and stratification /." Thesis, Connect to this title online; UW restricted, 1995. http://hdl.handle.net/1773/11007.

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14

Sharma, Rajan. "Cardiac risk stratification in renal transplant recipients." Thesis, St George's, University of London, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.423132.

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15

Tae, Yun-Jin. "Leisure constraints multiple hileararchy [sic] stratification perspectives /." Connect to this title online, 2007. http://etd.lib.clemson.edu/documents/1202500372.

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16

Kettley, Nigel Charles. "Gender, stratification, and attainment in further education." Thesis, University of Cambridge, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.615689.

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17

Zavier, Christian Chandrakumar. "Charge stratification for an internal combustion engine." Thesis, University of Canterbury. Mechanical Engineering, 1991. http://hdl.handle.net/10092/6418.

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The effect of charge stratification on the lean mixture combustion in a Ricardo E6 single cylinder, variable compression, spark ignition engine has been investigated. The charge stratification process involved injecting small amounts of pure methane gas into the engine cylinder through a modified spark plug just prior to ignition, at a relatively low pressure. Methane injection timing and methane injection duration (or injection rate) were controlled electronically and varied over a range of values. The charge stratification experiment was performed with two different types of inlet mixture. They were :- (1). gasoline fuel injected into the inlet manifold (2). methane gas carburetted through the inlet manifold To examine the effects of charge stratification, a few optimisation studies were undertaken prior to the main combustion experiments. A combustion chamber simulation was performed to visualise the effects of the velocity field on the injected methane gas. For this a constant volume bomb was built with the same bore as that of the Ricardo engine cylinder. A typical set of velocity fields around the spark plug gap location were established using hot wire anemometry, and relevant positions of the injected methane gas at different times from the injection point in the simulated velocity field were captured through Schlieren photography. The present work has led to the following conclusions:- (1). lean limit of the inducted fuel mixture is extended through the charge stratification process (2). effectiveness of charge stratification is well pronounced at lean air - fuel ratios (3). HC emission is higher with stratified charge combustion compared with base line operation (4). CO emission with stratified charge combustion is almost the same as or little lower than with base line operation, at leaner air - fuel ratios (5). the initially small and compact shape of the injected methane gas appearing in the Schlieren photographs could have a positive influence on the flame initiation phase.

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18

Lloyd, Katherine L. "Machine learning stratification for oncology patient survival." Thesis, University of Warwick, 2017. http://wrap.warwick.ac.uk/107703/.

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Personalised medicine for cancer treatment promises benefits for patient survival and effective use of medical resources. This goal requires the development of predictive models for the identification and implementation of biomarkers for the prediction of patient survival given treatment options. This thesis addresses research questions in this area. The systematic review detailed in Chapter 2 investigates the literature concerning the prediction of resistance to chemotherapy for ovarian cancer patients using statistical methods and gene expression measurements. The range of models used by studies in the systematic review highlights the popularity of traditional models, such as Cox proportional hazards, with few more complex models being utilised. In Chapters 3 and 4, new methods are presented for modelling right-censored survival data. Due to the nature of biomedical data, the methods used need to be flexible and adequately account for high dimensional, noisy data. Gaussian processes fulfil these requirements and were hence used for the development of three Gaussian process models for right-censored survival data. Chapter 3 details these models, and they are applied to synthetic and cancer data in Chapter 4. In all cases the Gaussian processes for survival were found to equal or outperform all comparison models, as measured by concordance index. Given the application to molecular cancer data, it was expected that the data would be high dimensional. Two feature selection methods are investigated in Chapter 5 for use with Gaussian processes to address this. In Chapter 6 a program is developed for the analysis of the data produced by a test for cancer mutations using qPCR. The automated program was designed to isolate the analysis from the user and produce results and reports for clinical use. It is observed that this approach of automated analysis would be suitable for application to any form of clinical test or complex predictive model without the requirement of user guidance.

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19

Pavel, Vera L. (Vera Lynn). "Stratification on the Skagit Bay tidal flats." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/78175.

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Thesis (Ph. D.)--Joint Program in Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Mechanical Engineering; and the Woods Hole Oceanographic Institution), 2012. Cataloged from PDF version of thesis. Includes bibliographical references (p. 79-84). Estuarine density stratification may be controlled primarily by cross-shore processes (analogous to longitudinal control in narrow estuaries), or by both cross- and alongshore processes (typical of coastal plumes). Here field observations and numerical modeling are used to investigate stratification on the low-sloped, periodically inundated Skagit Bay tidal flats. Advection of stratification by the depth-averaged velocity, straining of the horizontal density gradient by velocity shear, and turbulent mixing are shown to be the dominant processes. On the south-central flats (near the south fork river mouth) velocities are roughly rectilinear, and the largest terms are in the major velocity direction (roughly cross-shore). However, on the north flats (near the north fork river mouth), velocity ellipses are nearly circular owing to strong alongshore tidal flows and alongshore stratification processes are important. Stratification was largest in areas where velocities and density gradients were aligned. The maximum stratification occurred during the prolonged high water of nearly diurnal tides when advection and straining with relatively weak flows increased stratification with little mixing. Simulations suggest that the dominance of straining (increasing stratification) or mixing (decreasing stratification) on ebb tides depends on the instantaneous Simpson number being above or below unity. by Vera L. Pavel. Ph.D.

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20

Ruf, François. "Stratification sociale en économie de plantation ivoirienne." Paris 10, 1988. http://www.theses.fr/1988PA100155.

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L'auteur propose une interprétation de l'économie de plantation ivoirienne depuis sa phase minière ou pionnière jusqu'à sa phase de raréfaction des facteurs de production : terre, foret, travail. Le problème de la reproduction ou de la disparition de l'économie de plantation est pose. L'économie de plantation ivoirienne s'est construite sur la rencontre de la terre et du travail, entre ceux qui détenaient initialement la terre, principalement les "autochtones" et ceux qui contrôlaient le travail, principalement les "allogènes". De cette rencontre, le capital est absent. Il y a bien un paradoxe. D'une part, l'arbre cacaoyer devient le capital d'exploitation, acquis à base de travail et de terre, et donc accessible au plus grand nombre. L'économie de plantation ivoirienne illustre un processus d'accumulation primitive du capital, relativement égalitaire puisqu'accessible a une majorité. Simultanément, l'arbre-cacaoyer est un capital crée et approprie individuellement, favorisant le processus d'éclatement des régulations sociales visant à limiter l'inégalité de richesse. Le capital cacaoyer ou caféier tend donc à induire une différenciation sociale qui est réelle mais limitée et partiellement réversible. Aujourd'hui, le capital est construit : 3 millions d'hectares de plantations de café et de cacao pour 500. 000 exploitations. Aujourd'hui, le renouvellement du capital plantation passe par un besoin nouveau en crédit, par de nouveaux itinéraires techniques, par une plus grande sécurité foncière, par des bouleversements dans l'organisation paysanne et ses rapports avec l'état. Par manque de trésorerie et de crédit, de grandes exploitations peuvent se morceler ou disparaitre au profit de plus petites. Dans le même temps, de nouvelles grandes exploitations peuvent se constituer à la faveur de l'introduction du capital d'exploitation dans le système de production. Le capitalisme agraire, jusque-là marginal ou inexistant en cacao culture ivoirienne aurait peut-être la une chance de développement, chance compromise par la crise cacaoyère des années 1980-90 The author proposes an interpretation of the plantation economy in Ivory Coast from the "mining" or pioneer phase to the phase of scarcity of factors of production: land, forest and labor. The problem of the reproduction or disappearance of the plantation economy is described. The plantation economy in Ivory Coast grew from the encounter between land and labor, between those who initially held the land - mainly "autochthons" - and those - mainly foreign - who controlled the labor. Capital was not involved in this meeting. There is a paradox. Firstly, the cacao-tree has become exploitation capital, based on labor and land and thus accessible to a large number of people. The Ivory Coast plantation economy illustrates a primitive capital accumulation process which is relatively egalitarian since capital is available to the majority. At the same time, the cacao-tree is capital which is created and acquired individually, enhancing the process of breaking down the social regulations aimed at limiting inequality of wealth. Cacao or coffee capital thus tends to induce social differentiation which is real but limited and partially reversible. The capital has now been formed: 3 million hectares of coffee and cocoa plantations involving 500,000 holdings. Today, the renewal of plantation capital has new credit requirements, new technical procedures, greater landholding security and upheavals in peasant organization and its relations with the state. Because of lack of cash and credit, large holdings may be divided up or disappear to the profit of smaller holdings. At the same time, new large holdings may be created by the in the injection of operating capital into the farming system. Agrarian capital, hitherto marginal or nonexistent in cacao-growing in Ivory Coast, may thus perhaps have a chance of developing, but these opportunities are compromised by the 1980-90 cacao crisis

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21

SHENG, XIAOHUA. "HUMAN POPULATION STRATIFICATION AND GENETIC ASSOCIATION STUDIES." University of Cincinnati / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1196096932.

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22

Gacem, Iyadh. "Sondages : la post-stratification et ses limites." Grenoble 2, 2006. http://www.theses.fr/2006GRE21008.

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L'objectif de cette thèse est de rechercher des approximations suffisamment précises du biais et de la variance d'estimateurs post-stratifiés pour pouvoir ensuite étudier leurs comportements limites. Le travail porte sur l'estimation d'un total selon un plan simple. Le premier chapitre donne ces approximations pour la post-stratification sur un seul critère (ou sur les modalités croisées de plusieurs critères). Les formules sont validées par un échantillonnage dans un fichier réel et sur des situations construites. On peut alors mesurer les effets de l'accroissement de la finesse de la partition induite par le critère (c'est-à-dire du nombre de modalités de calage). On constate que les dégradations du biais et de la variance sont lentes. Le chapitre 2 considère la post-stratification couramment utilisée : le calage sur les marges de plusieurs critères. Les approximations établies sont validées comme précédemment. L'équivalence de toute une classe de distances de calage est démontrée. D'une façon générale le biais (au carré) de l'estimateur reste inférieur à sa variance et la dégradation de cette dernière intervient brutalement de façon très sensible lorsque l'on augmente le nombre de catégories de calage. La variété des simulations effectuées incite à une règle de précaution : ne pas dépasser un nombre égal à n/30. Finalement dans les deux derniers chapitres on étudie les cas où les marges de référence sont entachées d'erreurs aléatoires ou déterministes The purpose of the thesis is to establish approximations for the bias and the variance for post-stratified estimators, which are precise enough so as to study limiting behaviours. Estimators considered are for a total under simple random sampling. The first chapter gives approximations for poststratification on a single variable (or on cross-categories of several variables). These are validated on real data as well as on artificial situations. Thus, it is possible to measure the effects of an increasing thin partition of the population (i. E. Of the number of calibration categories). In fact bias and variance deteriorates rather slowly. Chapter 2 considers poststratification as it is mostly used, i. E. Calibration on the marginals of several variables. Approximations are validated as previously. The equivalence of a large class of calibration distances is also shown. Generally speaking, the bias (squared) remains smaller than the variance and the latter, at some point, increases strongly when the number of calibration categories increases. From the variety of simulations completed, a conservative rule to be derived is to keep that number below n/30. Finally, the last two chapters are devoted to situations where the reference margins are not perfectly known, containing either random or deterministic errors

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23

Grandjean, Vincent. "Stratification logarithmique, determination finie relative, discriminant residuel." Rennes 1, 2000. http://www.theses.fr/2000REN10131.

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On s'interesse aux germes de fonctions lisses (c , r ou c ) a l'origine de k n ou k est r ou c, dont le lieu singulier est analytique. Dans la categorie holomorphe le travail de pellikaan a defini un cadre assez precis pour etudier ce probleme. Dans le cas c , aucune telle etude systematique n'a ete entreprise. Le chapitre 1 rappelle certains resultats classiques de la theorie des singularites des germes d'applications lisses, afin desouligner quels nos objectifs. Le chapitre 2 traite des proprietes de la stratification logarithmique d'un germe d'ensemble analytique coherent en ayant montre au prealable que la coherence de est equivalente a la coherence du module des champs de vecteurs analytiques reels tangents a. Quand est un diviseur libre, on montre que le lieu singulier de est muni d'une structure determinantielle et ainsi un espace de cohen-macauley. Dans le chapitre 3 on definit une theorie de la determination finie (c ) relativement a un ideal ferme de type fini i verifiant trois hypotheses (naturelles) supplementaires. Les ideaux de germes de fonctions c engendres par un nombre fini de fonctions analytiques sont de tels ideaux. En considerant les trois relations d'equivalence r i, a i et k i, on trouve les theoremes usuels de determination finie et de deploiement versel relativement au groupe considere. Dans le dernier chapitre on revient aux singularites complexes. Soit f un germe de fonction singuliere le long de et de codimension relative finie (a droite) le long de , et soit g un deploiement mini-versel tronque. On definit le module jacobien residuel tronque m r c g et son support rc g le lieu critique residuel tronque. Quand est un diviseur libre euler verifiant dimrc g ( c p 1) = p 2, les types

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24

Varghese, Sibu. "Biomarkers for risk stratification in Barrett's oesophagus." Thesis, University of Cambridge, 2015. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708774.

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25

Ruf, François. "Stratification sociale en économie de plantation ivoirienne." Lille 3 : ANRT, 1990. http://catalogue.bnf.fr/ark:/12148/cb37618346n.

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26

Korrup, Sylvia Elizabeth. "Mothers and the process of social stratification /." [S.l.] : Interuniversity center for social science theory and methodology, 2000. http://catalogue.bnf.fr/ark:/12148/cb37628685k.

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Proefschrift--Universiteit Utrecht--Utrecht, 2000. Mention parallèle de titre ou de responsabilité : De @invloed van de moeder op het proces van statusverwerving. Résumé en néerlandais. Bibliogr. p. 138-150.

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27

AZZOLLINI, LEO. "Social Stratification, Life Course, and Political Inequality." Doctoral thesis, Università Bocconi, 2021. http://hdl.handle.net/11565/4035715.

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No abstract available The topic of this dissertation is the relationship between social stratification and inequality in electoral participation in European countries, examined from a life course perspective. This participatory inequality across social strata is considered as particularly worrisome by social scientists, due to a potential vicious circle arising between socio-economic and political inequalities. The goal of this dissertation is to contribute to the exploration of said vicious circle, focusing on theoretical perspectives originating in sociology, at the intersection of social stratification and life course research: unemployment scarring, precarious work, relative cohort size, and age-class intersections. Broadly, I posit how the impact of individual social stratification on turnout is moderated by contextual-level dynamics, such as the unemployment rate, the size of the birth cohort, and the ideological convergence in the party system. I test the hypotheses by fitting logistic and multilevel regressions to data from the European Social Survey, combined with data from the EUROSTAT, Fraser Institute’s World Project, and the International Database of the US Census for Chapters 1-3. In Chapter 4, I integrate data from British Social Attitudes, the British Election Study, and the Manifesto Research on Political Participation in the case study of Great Britain. The key findings are the following: unemployment scarring decreases electoral participation by 10%, but its impact is amplified (up to 17%) by lower contextual unemployment, and nullified by higher levels of the latter. Precarious work decreases probability of voting in 21 European countries, on top of traditional predictors such as social class and education. In contrast with the Easterlin Hypothesis, larger Relative Cohort Size increases electoral participation, especially in upper social strata. Ideological convergence in Great Britain depresses the turnout of the working class and the self-employed, and this is driven mainly by younger cohorts within those classes. In sum, integrating the social stratification and life course approaches sheds new light on how inequality in electoral participation is jointly affected by individual and contextual characteristics. In future work, this joint approach may orient research on additional socio-political outcomes, towards a broader research programme on the Political Sociology of Inequalities.

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28

AZZOLLINI, LEO. "Social Stratification, Life Course, and Political Inequality." Doctoral thesis, Università Bocconi, 2021. http://hdl.handle.net/11565/4035714.

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No abstract available The topic of this dissertation is the relationship between social stratification and inequality in electoral participation in European countries, examined from a life course perspective. This participatory inequality across social strata is considered as particularly worrisome by social scientists, due to a potential vicious circle arising between socio-economic and political inequalities. The goal of this dissertation is to contribute to the exploration of said vicious circle, focusing on theoretical perspectives originating in sociology, at the intersection of social stratification and life course research: unemployment scarring, precarious work, relative cohort size, and age-class intersections. Broadly, I posit how the impact of individual social stratification on turnout is moderated by contextual-level dynamics, such as the unemployment rate, the size of the birth cohort, and the ideological convergence in the party system. I test the hypotheses by fitting logistic and multilevel regressions to data from the European Social Survey, combined with data from the EUROSTAT, Fraser Institute’s World Project, and the International Database of the US Census for Chapters 1-3. In Chapter 4, I integrate data from British Social Attitudes, the British Election Study, and the Manifesto Research on Political Participation in the case study of Great Britain. The key findings are the following: unemployment scarring decreases electoral participation by 10%, but its impact is amplified (up to 17%) by lower contextual unemployment, and nullified by higher levels of the latter. Precarious work decreases probability of voting in 21 European countries, on top of traditional predictors such as social class and education. In contrast with the Easterlin Hypothesis, larger Relative Cohort Size increases electoral participation, especially in upper social strata. Ideological convergence in Great Britain depresses the turnout of the working class and the self-employed, and this is driven mainly by younger cohorts within those classes. In sum, integrating the social stratification and life course approaches sheds new light on how inequality in electoral participation is jointly affected by individual and contextual characteristics. In future work, this joint approach may orient research on additional socio-political outcomes, towards a broader research programme on the Political Sociology of Inequalities.

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29

Alburai'Si, Kholoud Mubarak. "Stratification of breast cancer patients : a proteomic approach." Thesis, King's College London (University of London), 2016. https://kclpure.kcl.ac.uk/portal/en/theses/stratification-of-breast-cancer-patients(a8102723-9f21-4495-8401-d3e8ce503968).html.

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Breast cancer represents a heterogeneous collection of different diseases characterized by different pathological and biological features, clinical presentation, clinical behaviour, response to treatment and outcome. In current practice, pathological diagnosis and classification of breast cancer is based mainly on well-established traditional morphologic features. However, morphological features alone do not adequately reveal the molecular heterogeneity and complexity of breast cancer. Still, there are relatively few biomarkers widely used in prognostication in invasive breast cancer and in predicting response to targeted therapies, and even fewer of value in the clinical management of the pre-invasive disease of ductal carcinoma in situ (DCIS). There is therefore an unmet need for biomarkers for better classification, better prediction of prognosis and of prediction of response to therapy for both invasive breast carcinoma and DCIS. The co-expression of a HER2/HER3 combination results in more aggressive tumour growth and is associated with endocrine and chemotherapy resistance, driven not simply by receptor expression but also by signalling via the receptors dimers. Therefore, methods which directly query signalling pathway activation in breast cancer specimens are anticipated to provide important insights into the molecular ‘‘logic’’ that distinguishes cancer from normal tissues and potentially to have an important impact on personalized intervention strategies. The aim of this thesis has been directed at evaluating candidate biomarkers in breast cancer. This has been targeted at examining attributes associated with known functional properties of candidate drivers of disease or resistance to treatment rather than those traditionally based on altered expression of these biomarkers. Specifically, the work was directed at the HER1-3 members of the EGFR family of growth factor receptor in breast cancer. In this project I have in part developed, tested and evaluated two methods, which have the ability to detect protein-protein complexes at a single molecule level and thus allow the study of signalling pathways in situ. The first method is an in-house coincidence detection technology created from two recombinant fusion proteins and the second is a commercially available proximity ligation assay (PLA) method. Both approaches were able to detect the target proteins with high sensitivity and specificity, however the proximity ligation assay was subsequently used here to assess the protein complexes and activation status of the EGFR family in breast cancer patient’s samples. The patient study cohort is derived from a consecutive series of approximately 293 cases of primary operable invasive breast cancers obtained from the Guy’s and St Thomas (King’s Health Partner’s) Breast Cancer Biobank archive presenting between 1990 and 1992. In these cases, 9 different biomarkers were studied for HER family expression level, dimer expression and activation status using proximity ligation assays (PLAs). The relationship between HER activation status, dimer expression and relapse free survival (RFS) was investigated and stratified multivariate regression analysis identified factors influencing patient prognosis. In conclusion, PLA successfully and reproducibly detected HER protein complexes and phosphorylation in vivo. A significant association was identified between high levels of phosphorylated HER2 and reduced recurrence-free survival (RFS) in invasive lobular carcinoma (p = 0.04, HR 0.99, 95% CI: 0.997-1.002). High levels of HER1/HER3 dimers were associated with reduced RFS in T1 (<2cm) breast cancer patients, (p = 0.02, HR 1.84, 95% CI: 1.08-3.13). Similarly, high levels of HER1/HER3 and HER2/HER3 dimers were associated with reduced RFS in breast cancer patients with N1 nodal status (p <0.0001, HR 1.84, 95% CI: 0.58-1.93) and (p <0.0001, HR 0.64, 95% CI: 0.45-0.90) respectively). Work in this thesis demonstrates that in situ detection of HER protein complexes and activation status can be monitored robustly and with specificity in clinical specimens, providing novel prognostic information. This technique was also applied successfully to assess the HER family in a smaller number of DCIS cases. This novel technique and approach could potentially be applied for patient stratification and assist in the selection of more individualized treatment options according to tumour molecular characteristics.

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30

Lawrie, Andrew. "Rayleigh-Taylor mixing : confinement by stratification and geometry." Thesis, University of Cambridge, 2010. https://www.repository.cam.ac.uk/handle/1810/225125.

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Rayleigh-Taylor instability has been an area of active research in fluid dynamics for the last twenty years, but relatively little attention has been paid to the dynamics of problems where Rayleigh-Taylor instability plays a role, but is only one component of a more complex system. Here, Rayleigh-Taylor instability between miscible fluids is examined in situations where it is confined by various means: by geometric restriction, by penetration into a stable linear stratification, and by impingement on a stable density interface. Water-based experiments are modelled using a variety of techniques, ranging from simple hand calculation of energy exchange to full three-dimensional numerical simulation. Since there are well known difficulties in modelling unconfined Rayleigh-Taylor instability, the confined test cases have been sequenced to begin with dynamically simple benchmark systems on which existing modelling approaches perform well, then they progress to more complex systems and explore the limitations of the various models. Some work on the phenomenology of turbulent mixing is also presented, including a new experimental technique that allows mixed fluid to be visualised directly, and an analysis of energy transport and mixing efficiency in variable density flows dominated by mixing.

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31

Townsend, Daphne. "Clinical trial of estimated risk stratification prediction tool." Thesis, University of Ottawa (Canada), 2007. http://hdl.handle.net/10393/27926.

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This work presents doctors with a model of the estimated degree of risk of rare and important neonatal outcomes to aid in better decisions and improved allocation of equipment and resources. An extensive list of admission day parameters is reduced to minimum variable sets to create models for outcomes that are relevant to decision-making in the neonatal intensive care unit. Models are applied to a special collection of cases and compared to neonatologists' risk estimates. A comparative analysis of physician's predictions and the models' discrimination abilities highlights areas of success and areas that can be improved for future trials. Doctors responded positively to the prediction interface concept and to the estimated risk stratification models. Physicians' strengths identified outcomes that could benefit from increased sensitivity. A substantial effort was made to conduct the usability and performance evaluations within the ethical standards that are especially important for engineering healthcare management applications.

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32

Owen, Craig Nielsen Francois. "Cross-cultural analysis of stratification with societal taxonomies." Chapel Hill, N.C. : University of North Carolina at Chapel Hill, 2007. http://dc.lib.unc.edu/u?/etd,1311.

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Thesis (M.A.)--University of North Carolina at Chapel Hill, 2007. Title from electronic title page (viewed Apr. 25, 2008). "... in partial fulfillment of the requirements for the degree of Masters of Arts in the Department of Sociology." Discipline: Sociology; Department/School: Sociology.

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33

Souza, Alejandro Jose Gerardo. "Controls on stratification in the Rhine ROFI system." Thesis, Bangor University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.387212.

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34

Leslie, Stephen. "Inference of Population Stratification Using Population Genetic Data." Thesis, University of Oxford, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.504423.

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35

Lewis, Kevin. "Stratification in the Early Stages of Mate Choice." Thesis, Harvard University, 2012. http://dissertations.umi.com/gsas.harvard:10477.

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Sociologists have long studied mate choice patterns to understand the shape of stratification systems. Romantic pairing involves intimacy and trust, and is therefore a prime indicator of the extent to which members of different social groupings (race/ethnicity, social class, education, religion) accept each other as social equals. The majority of this literature focuses on marriage, given the commitment marriage implies and the availability of nationally-representative data. In this dissertation, I examine the opposite end of the relationship spectrum: The initial screening and sorting process whereby strangers consider each other as potential mates; express interest in some subset of this population but not others; and find that this interest is or is not reciprocated. This beginning stage in mate choice is particularly important for our understanding of social boundaries because personality factors are likely to matter less and social characteristics to matter more. Yet because these initial forays into relationships are typically unobserved, we know very little about whom people consider as potential mates in the first place. I ask the following questions, corresponding to three empirical chapters: First, how do individuals from different status backgrounds vary in the types of strategies that they pursue and the degree of success that they achieve? Second, what underlying dynamics of homophily, competition, and gender asymmetry give rise to observed patterns of interaction, and under what circumstances do some of these boundaries break down? Third, how do strategies as well as preferences vary at different stages of selection, and at what point is homogeneity created? To answer these questions, I use detailed longitudinal data from a popular online dating site. These data are particularly useful for the study of social inequality not only due to the unique quantity and nature of information that is available, but also because online dating has become one of the primary ways that singles meet and marry today. Sociology

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36

Lampard, Richard James. "An empirical study of marriage and social stratification." Thesis, University of Oxford, 1992. http://ora.ox.ac.uk/objects/uuid:fb961361-18b3-4801-bd83-8d2bc5b234d5.

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The dual objectives of this thesis are to assess the merits of certain statistical methods as applied to sociological data and to use statistical methods to produce interesting and worthwhile substantive results. The main statistical focus of the thesis is the analysis of two-way tables, for which purpose association models and correspondence analysis are used. Some of the tables analysed require the application of quasi-association models and association models with more than one dimension. Elsewhere in the thesis a proportional hazards model and various log-linear models are fitted. The substantive focus of the thesis is the relationship between marital formation/dissolution and social stratification in modern Britain. Particular attention is paid to assortative marriage for social status, with the relationships between spouses' occupations, educational levels and social origins being considered in detail. Assortative marriage for religion and for party political identification/voting intention are also examined. The data analysed come from a variety of social surveys, including both government surveys (e.g. various General Household Surveys, and the Family Formation Survey) and academic surveys (e.g. the Oxford Mobility Survey and the Social Change and Economic Life Initiative survey). The thesis conclusively demonstrates the utility of association models, log-linear models and proportional hazards models as applied to data relating to marital formation/dissolution. Among the numerous substantive findings are that there was a significant post-war decline in the strength of the relationship between spouses' social origins, and that unemployment appears to cause an increase in the risk of marital dissolution.

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37

Green, Susan Elizabeth. "Risk stratification in hereditary non-polyposis colorectal cancer." Thesis, University of Newcastle Upon Tyne, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.387479.

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38

Noble, Trevor. "Social mobility trends and social stratification in Britain." Thesis, University of Sheffield, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.245787.

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39

Jiang, Jiaxin M. Eng Massachusetts Institute of Technology, and Andrew Steverson. "SKU stratification methods in the consumer products industry." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/112863.

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Thesis: M. Eng. in Supply Chain Management, Massachusetts Institute of Technology, Supply Chain Management Program, 2017. Cataloged from PDF version of thesis. Includes bibliographical references (page 40). For companies with a large number of Stock Keeping Units (SKUs), it is extremely challenging, if not impossible, to manage the SKUs individually. Therefore, companies stratify SKUs into different classes and manage them by class. Currently, most companies identify SKU stratification based on the single factor of sales volume. This thesis explores more comprehensive analysis methods that can consider multiple SKU characteristics. We applied four methods (Single Factor Analysis, Dual-Matrix Analysis, Analytical Hierarchy Process, and Cluster Analysis) to the data of a company in the Consumer Packaged Goods industry. The factors considered were velocity, volatility, and profit margin. Our research indicates that the Analytical Hierarchy Process is the most viable and comprehensive method for stratifying SKUs. It allows for a flexible number of stratification factors, different importance levels of the factors, and user control of the number of classes and class sizes. By applying the Analytical Hierarchy Process to SKU stratification, companies will be able to carry the right inventory for the right SKUs, and improve customer service. by Jiaxin Jiang and Andrew Steverson. M. Eng. in Supply Chain Management

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40

Sharples, Jonathan. "Time dependent stratification regions of large horizontal gradient." Thesis, Bangor University, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.304875.

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41

Constantinides, Savvas Sophocles. "Risk stratification for revascularisation in acute ischaemic syndromes." Thesis, University of Leicester, 2005. http://hdl.handle.net/2381/29878.

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Aim of study: PHASE 1: To identify those clinical and simple anatomical variables that could predict early (30 days), medium (6 month) and late (1 year) mortality following Percutaneous Coronary Intervention (PCI) for non ST segment elevation Acute Coronary Syndromes (NSTEACS). To compare outcomes in a contemporary group undergoing Coronary artery Bypass Surgery (CABG) and to examine which clinical variables are related to early mortality. PHASE II: To develop a PCI risk score and apply it to the same database. To then apply the risk score to a separate cohort of patients for validation.;Methods: Data from 630 consecutive patients undergoing PCI for NSTEACS between January 1999 and December 2000 were analysed. Data from 522 patients who underwent CABG were also analysed for similar variables and outcomes were noted. The derived 8 variable PCI risk score was applied on the following 500 consecutive patients undergoing PCI for NSTEACS between January 2001 and August 2002.;Results: Age, partial revascularisation, peripheral vascular disease, diabetes mellitus and left ventricular impairment were found to be significant predictors of mortality following PCI for ACS. A 'risk-score' model including age, LV impairment, multi-vessel disease, diabetes, renal impairment, peripheral vascular disease and female sex was then tested on the same cohort and found to be good in predicting death following PCI. In the surgical study group higher rates of mortality were found with age, clinical features of heart failure, LV impairment, chronic airways disease and cerebrovascular disease. The derived PCI risk score was found on validation to be a good predictive tool for mortality.;Conclusion: Individualisation of risk stratification for patients undergoing revascularisation for acute coronary syndromes is not only possible but also simple using easily available clinical information by the bedside.

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42

Khan, Sohail Q. "Risk stratification of myocardial infarction using cardiac peptides." Thesis, University of Leicester, 2008. http://hdl.handle.net/2381/29901.

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We investigated the TIMI risk score, Cardiotrophin-1 (CT-1) myotrophin and MPO in combination with NTproBNP at predicting adverse outcome following AMI. We recruited 596 patients with AMI. Patients were TIMI risk scored. The concentrations of CT-1, myotrophin, MPO and NTproBNP were measured using non-competitive immunoassays. All patients were followed-up for death, recurrent MI, heart failure (HF) and MACE (death, MI and need for urgent revascularisation). Mortality was related to higher TIMI score (p=0.029) and NTproBNP levels (<0.0001). NTproBNP was an independent predictor of mortality (OR 4.21). The receiver-operating curve (ROC) area under curve (AUC) for NTproBNP was greater than TIMI risk score (0.79 vs. 0.67). CT-1 was raised in death or HF (0.77 vs. 0.73fmol/ml; p=0.001). In multivariate analysis CT-1 (HR 1.5) and NTproBNP (HR2.1) predicted death or HF independently of clinical factors. The ROC AUC for CT-1 was 0.62; NTproBNP was 0.77; AUC for combined markers was 0.84. Myotrophin was raised in patients with death, death or HF and MACE. In Cox analysis myotrophin (HR 5.07) and NTproBNP (HR 7.15) independently predicted death. Myotrophin was better at predicting death or HF (HR 2.35) and MACE (HR 1.69). Median MPO was raised in patients experiencing death, death or MI, death or HF and MACE. In Cox analysis median MPO predicted death (HR 13.05) and death or non-fatal MI (HR 5.07). A multimarker approach with NTproBNP may be useful for risk stratification in AMI patients.

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43

Dmytryshyn, Andrii. "Skew-symmetric matrix pencils : stratification theory and tools." Licentiate thesis, Umeå universitet, Institutionen för datavetenskap, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-87501.

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Investigating the properties, explaining, and predicting the behaviour of a physical system described by a system (matrix) pencil often require the understanding of how canonical structure information of the system pencil may change, e.g., how eigenvalues coalesce or split apart, due to perturbations in the matrix pencil elements. Often these system pencils have different block-partitioning and / or symmetries. We study changes of the congruence canonical form of a complex skew-symmetric matrix pencil under small perturbations. The problem of computing the congruence canonical form is known to be ill-posed: both the canonical form and the reduction transformation depend discontinuously on the entries of a pencil. Thus it is important to know the canonical forms of all such pencils that are close to the investigated pencil. One way to investigate this problem is to construct the stratification of orbits and bundles of the pencils. To be precise, for any problem dimension we construct the closure hierarchy graph for congruence orbits or bundles. Each node (vertex) of the graph represents an orbit (or a bundle) and each edge represents the cover/closure relation. Such a relation means that there is a path from one node to another node if and only if a skew-symmetric matrix pencil corresponding to the first node can be transformed by an arbitrarily small perturbation to a skew-symmetric matrix pencil corresponding to the second node. From the graph it is straightforward to identify more degenerate and more generic nearby canonical structures. A necessary (but not sufficient) condition for one orbit being in the closure of another is that the first orbit has larger codimension than the second one. Therefore we compute the codimensions of the congruence orbits (or bundles). It is done via the solutions of an associated homogeneous system of matrix equations. The complete stratification is done by proving the relation between equivalence and congruence for the skew-symmetric matrix pencils. This relation allows us to use the known result about the stratifications of general matrix pencils (under strict equivalence) in order to stratify skew-symmetric matrix pencils under congruence. Matlab functions to work with skew-symmetric matrix pencils and a number of other types of symmetries for matrices and matrix pencils are developed and included in the Matrix Canonical Structure (MCS) Toolbox.

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44

Pieper, Robert Joseph. "Surface Property Modification of Coatings via Self-Stratification." Diss., North Dakota State University, 2010. https://hdl.handle.net/10365/26491.

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Biological fouling occurs everywhere in the marine environment and is a significant problem for marine vessels. Anti-fouling coatings have been used effectively to prevent fouling; however, these coatings harm non-targeted sea-life. Fouling-release coatings (FRC) appear to be an alternative way to combat fouling. FRC do not necessarily prevent the settlement of marine organisms but rather allow their easy removal with application of shear to the coatings surface. These coatings must be non-toxic, non-leaching, have low surface energy, low modulus, and durability to provide easy removal of marine organisms. Here the goal is to develop FRC based on thermosetting siloxane-polyurethane, amphiphilic polyurethane, and zwitterionic/amphiphilic polyurethane systems. A combinatorial high-throughput approach has been taken in order to explore the variables that may affect the performance of the final coatings. Libraries of acrylic polyols were synthesized using combinatorial high-throughput techniques by either batch or semi-batch processes. The design of the experiments for the batch and semi-batch processes were done combinatorially to explore a range of compositions and various reaction process variables that cannot be accomplished or are not suitable for single reaction experiments. Characterization of Rapid-GPC, high-throughput DSC, and gravimetrically calculated percent solids verified the effects of different reaction conditions on the MW, glass transition temperatures, and percent conversion of the different compositions of acrylic polyols. Coatings were characterized for their surface energy, pseudobarnacle pull-off adhesion, and were subjected to bioassays including marine bacteria, algae, and barnacles. From the performance properties results the acrylic polyol containing 20% hydroxyethyl acrylate and 80% butyl acrylate was selected for further siloxane-polyurethane formulations and were subjected to the same physical, mechanical, and performance testing. Amiphiphilic copolymers based on PDMS molecular weight and the addition of PEG based polymer blocks on the properties of acrylic-polyurethane coatings were explored. The key properties screened were surface energy, determined by contact angle measurements using water and methylene iodide, dynamic water contact angle, and pseudobarnacle adhesion properties. The data from all of the biological assays indicates that the novel coatings were able to resist fouling and have low fouling adhesion for the broad variety of fouling organisms tested.

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45

Plessz, Marie. "Stratification sociale et générations en Europe centrale postcommuniste." Paris, Institut d'études politiques, 2009. http://www.theses.fr/2009IEPP0050.

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La thèse est une étude des inégalités entre cohorte de naissance suite à la sortie du communisme en Pologne, Hongrie et République tchèque. La thèse s'appuie sur des données statistiques variées couvrant les trois pays sur plus de vingt ans. Nous posons un cadre d'analyse des dynamiques générationnelles, de la stratification sociale et du changement social adapté au contexte de la transformation postcommuniste. Puis nous replaçons la transformation dans le temps long des évolutions économiques sociales et démographiques. Ensuite nous montrons comment le marche du travail et la stratification sociale ont été bouleversés par la transformation. La chute du nombre d'emplois, en particulier dans l'industrie et la déstandardisation de la relation d'emploi sont les phénomènes les plus marquants. Nous montrons que la montée des inégalités de rémunération va de pair avec la modification des déterminants de l’accès à l’emploi et des salaires. L’âge compte de moins en moins, l’éducation de plus en plus. Enfin nous décrivons et analysons les inégalités entre cohortes dans l’accès aux professions les plus qualifiées. Les inégalités diffèrent d’un pays à l’autre. Pour les expliquer nous mobilisons l’accès à l’éducation supérieure sous le communisme, la recomposition du cycle de vie après 1989, et l’évolution de la structure des emplois avant et après 1989. Enfin l’accès croissant des femmes à l’éducation et à l’emploi dans les secteurs des services affecte aussi les chances de réussites des cohortes masculines. Au final nous soulignons l’intérêt d’analyser ensemble les questions d’âge et de genre sur le marché du travail pour mieux comprendre les processus de stratification sociale This dissertation studies intercohort inequalities after the end of the communist regimes in Poland, Hungary and the Czech Republic. It relies on a wide range of statistical data covering the three countries over more then 20 years. First we suggest a theoretical framework in order to understand cohort dynamics, social stratification and social change in the specific context of the postcommunist transformation. Then we replace the transition in the long run with respect to social, economic and demographic changes. We show how the drop in employment and especially in manufacturing have deeply transformed the stratification process, along with the de-standardisation of the employment relationship. We show that the rising earnings inequalities come along with new pay determinants. The chances to get a job are also different. Age is less relevant while education becomes prominent. Finally we deal with cohort inequality in access to the most qualified occupations. They vary from country to country so they cannot be explained by the sole transformation. We show how access to higher education under communist rule, and the life cycle changes after 1989 as well as the changing employment structure during the last 60 years are the key to comprehend cohort dynamics in Central-Eastern Europe. The increasing female education and activity also affects males’ ability to succeed, especially since women are more employed in service activities. In the end, the interplay between age and sex on the labor market is underlined as especially relevant for the understanding of social stratification processes

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46

Nagata, Koji. "TURBULENCE STRUCTURE AND TRANSPORT PHENOMENA IN DENSITY STRATIFICATION." Kyoto University, 2000. http://hdl.handle.net/2433/151546.

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47

Westfall, R. H. "Objectivity in stratification, sampling and classification of vegetation." Pretoria : [s.n.], 2009. http://upetd.up.ac.za/thesis/available/etd-09032009-212008/.

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48

Landi, Isotta. "Stratification of autism spectrum conditions by deep encodings." Doctoral thesis, Università degli studi di Trento, 2020. http://hdl.handle.net/11572/252684.

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This work aims at developing a novel machine learning method to investigate heterogeneity in neurodevelopmental disorders, with a focus on autism spectrum conditions (ASCs). In ASCs, heterogeneity is shown at several levels of analysis, e.g., genetic, behavioral, throughout developmental trajectories, which hinders the development of effective treatments and the identification of biological pathways involved in gene-cognition-behavior links. ASC diagnosis comes from behavioral observations, which determine the cohort composition of studies in every scientific field (e.g., psychology, neuroscience, genetics). Thus, uncovering behavioral subtypes can provide stratified ASC cohorts that are more representative of the true population. Ideally, behavioral stratification can (1) help to revise and shorten the diagnostic process highlighting the characteristics that best identify heterogeneity; (2) help to develop personalized treatments based on their effectiveness for subgroups of subjects; (3) investigate how the longitudinal course of the condition might differ (e.g., divergent/convergent developmental trajectories); (4) contribute to the identification of genetic variants that may be overlooked in case-control studies; and (5) identify possible disrupted neuronal activity in the brain (e.g., excitatory/inhibitory mechanisms). The characterization of the temporal aspects of heterogeneous manifestations based on their multi-dimensional features is thus the key to identify the etiology of such disorders and establish personalized treatments. Features include trajectories described by a multi-modal combination of electronic health records (EHRs), cognitive functioning and adaptive behavior indicators. This thesis contributes in particular to a data-driven discovery of clinical and behavioral trajectories of individuals with complex disorders and ASCs. Machine learning techniques, such as deep learning and word embedding, that proved successful for e.g., natural language processing and image classification, are gaining ground in healthcare research for precision medicine. Here, we leverage these methods to investigate the feasibility of learning data-driven pathways that have been difficult to identify in the clinical practice to help disentangle the complexity of conditions whose etiology is still unknown. In Chapter 1, we present a new computational method, based on deep learning, to stratify patients with complex disorders; we demonstrate the method on multiple myeloma, Alzheimer’s disease, and Parkinson’s disease, among others. We use clinical records from a heterogeneous patient cohort (i.e., multiple disease dataset) of 1.6M temporally-ordered EHR sequences from the Mount Sinai health system’s data warehouse to learn unsupervised patient representations. These representations are then leveraged to identify subgroups within complex condition cohorts via hierarchical clustering. We investigate the enrichment of terms that code for comorbidities, medications, laboratory tests and procedures, to clinically validate our results. A data analysis protocol is developed in Chapter 2 that produces behavioral embeddings from observational measurements to represent subjects with ASCs in a latent space able to capture multiple levels of assessment (i.e., multiple tests) and the temporal pattern of behavioral-cognitive profiles. The computational framework includes clustering algorithms and state-of-the-art word and text representation methods originally developed for natural language processing. The aim is to detect subgroups within ASC cohorts towards the identification of possible subtypes based on behavioral, cognitive, and functioning aspects. The protocol is applied to ASC behavioral data of 204 children and adolescents referred to the Laboratory of Observation Diagnosis and Education (ODFLab) at the University of Trento. In Chapter 3 we develop a case study for ASCs. From the learned representations of Chapter 1, we select 1,439 individuals with ASCs and investigate whether such representations generalize well to any disorder. Specifically, we identify three subgroups within individuals with ASCs that are further clinically validated to detect clinical profiles based on different term enrichment that can inform comorbidities, therapeutic treatments, medication side effects, and screening policies. This work has been developed in partnership with ODFLab (University of Trento) and the Predictive Models for Biomedicine and Environment unit at FBK. The study reported in Chapter 1 has been conducted at the Institute for Next Generation Healthcare, Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai (NY).

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49

Landi, Isotta. "Stratification of autism spectrum conditions by deep encodings." Doctoral thesis, Università degli studi di Trento, 2020. http://hdl.handle.net/11572/252684.

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This work aims at developing a novel machine learning method to investigate heterogeneity in neurodevelopmental disorders, with a focus on autism spectrum conditions (ASCs). In ASCs, heterogeneity is shown at several levels of analysis, e.g., genetic, behavioral, throughout developmental trajectories, which hinders the development of effective treatments and the identification of biological pathways involved in gene-cognition-behavior links. ASC diagnosis comes from behavioral observations, which determine the cohort composition of studies in every scientific field (e.g., psychology, neuroscience, genetics). Thus, uncovering behavioral subtypes can provide stratified ASC cohorts that are more representative of the true population. Ideally, behavioral stratification can (1) help to revise and shorten the diagnostic process highlighting the characteristics that best identify heterogeneity; (2) help to develop personalized treatments based on their effectiveness for subgroups of subjects; (3) investigate how the longitudinal course of the condition might differ (e.g., divergent/convergent developmental trajectories); (4) contribute to the identification of genetic variants that may be overlooked in case-control studies; and (5) identify possible disrupted neuronal activity in the brain (e.g., excitatory/inhibitory mechanisms). The characterization of the temporal aspects of heterogeneous manifestations based on their multi-dimensional features is thus the key to identify the etiology of such disorders and establish personalized treatments. Features include trajectories described by a multi-modal combination of electronic health records (EHRs), cognitive functioning and adaptive behavior indicators. This thesis contributes in particular to a data-driven discovery of clinical and behavioral trajectories of individuals with complex disorders and ASCs. Machine learning techniques, such as deep learning and word embedding, that proved successful for e.g., natural language processing and image classification, are gaining ground in healthcare research for precision medicine. Here, we leverage these methods to investigate the feasibility of learning data-driven pathways that have been difficult to identify in the clinical practice to help disentangle the complexity of conditions whose etiology is still unknown. In Chapter 1, we present a new computational method, based on deep learning, to stratify patients with complex disorders; we demonstrate the method on multiple myeloma, Alzheimer’s disease, and Parkinson’s disease, among others. We use clinical records from a heterogeneous patient cohort (i.e., multiple disease dataset) of 1.6M temporally-ordered EHR sequences from the Mount Sinai health system’s data warehouse to learn unsupervised patient representations. These representations are then leveraged to identify subgroups within complex condition cohorts via hierarchical clustering. We investigate the enrichment of terms that code for comorbidities, medications, laboratory tests and procedures, to clinically validate our results. A data analysis protocol is developed in Chapter 2 that produces behavioral embeddings from observational measurements to represent subjects with ASCs in a latent space able to capture multiple levels of assessment (i.e., multiple tests) and the temporal pattern of behavioral-cognitive profiles. The computational framework includes clustering algorithms and state-of-the-art word and text representation methods originally developed for natural language processing. The aim is to detect subgroups within ASC cohorts towards the identification of possible subtypes based on behavioral, cognitive, and functioning aspects. The protocol is applied to ASC behavioral data of 204 children and adolescents referred to the Laboratory of Observation Diagnosis and Education (ODFLab) at the University of Trento. In Chapter 3 we develop a case study for ASCs. From the learned representations of Chapter 1, we select 1,439 individuals with ASCs and investigate whether such representations generalize well to any disorder. Specifically, we identify three subgroups within individuals with ASCs that are further clinically validated to detect clinical profiles based on different term enrichment that can inform comorbidities, therapeutic treatments, medication side effects, and screening policies. This work has been developed in partnership with ODFLab (University of Trento) and the Predictive Models for Biomedicine and Environment unit at FBK. The study reported in Chapter 1 has been conducted at the Institute for Next Generation Healthcare, Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai (NY).

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50

Calpe, Linares Miguel. "Etude numérique de la turbulence stratifiée 2D forcée par des ondes internes de gravité." Thesis, Université Grenoble Alpes, 2020. https://tel.archives-ouvertes.fr/tel-02612797.

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Les écoulements océaniques sont composés des tourbillons ayant une grandeéchelle horizontale et des ondes internes de gravité. Le spectre d'énergiecinétique suit le fameux spectre de Garrett et Munk qui est habituellementinterprété comme la signature des ondes internes de gravité. Notre motivationprincipale est donc de reproduire le régime de turbulence observé dans la natureavec un système forcé seulement avec des ondes.Les écoulements stratifiés bidimensionnels (2D) sur une section transversaleverticale diffèrent des écoulements stratifiés tridimensionnels par l'absence devorticité verticale et par la présence d'ondes et de modes de cisaillement. Dansce travail de thèse, nous effectuons une étude numérique de la turbulencestratifiée 2D forcée par des ondes internes de gravité. Nous éliminons les modesde cisaillement pour avoir un système uniquement constitué d'ondes.Contrairement aux études précédentes, le forçage est appliqué à une régionlocalisée de l'espace spectral. Nous forçons aussi les ondes avec une échellespatiale intermédiaire pour permettre le développement d'une cascade d'énergiedirecte et aussi inverse.Nous présentons d'abord les différents régimes de turbulence stratifiée 2D avecun intérêt particulier au régime typique de l'océan avec une fortestratification et un grand nombre de Reynolds. La dynamique de la cascaded'énergie est analysée par un bilan énergétique spectral. Ensuite, nousvérifions s'il est possible d'obtenir un régime de turbulence d'onde faible enréalisant un analyse spatio-temporelle. Nous étudions enfin le degréd'universalité de la turbulence stratifiée 2D par rapport au forçage The oceanic motions are composed of eddies with a very large horizontal scaleand 3D propagating internal gravity waves. Its kinetic energy spectra follow thewell-known Garrett and Munk spectrum, which is usually interpreted as thesignature of interacting internal gravity waves. Our main motivation is toreproduce the turbulence regime observed in nature by forcing waves.Two-dimensional (2D) stratified flows on a vertical cross-section differ fromits analogous three-dimensional flows in its lack of vertical vorticity,supporting only waves and shear modes. In this PhD work, we perform a numericalstudy of 2D stratified turbulence forced with internal gravity waves. We get ridof the shear modes, sustaining a system only with wave modes. Unlike precedentstudies, the forcing is applied to a localized region of the spectral space, inwhich forced internal waves have a similar time scale. We forceintermediate-scale waves to allow the dynamics to develop both upscale anddownscale energy cascade.We first present the different regimes of 2D stratified turbulence with aparticular interest in the ocean-like regime, i.e. strong stratification andlarge Reynolds number. The dynamics of the energy cascade is analysed by meansof the spectral energy budget. Furthermore, we check if it is possible to obtainturbulence driven by weakly non-linear ineracting waves by performing aspatio-temporal analysis. To conclude, we report results of numericalsimulations forced either on the vorticity or on the eigenmode of theNavier-Stokes equations in order to study the degree of universality of 2Dstratified turbulence with respect to the forcing

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Tesis sobre el tema "Stratification"

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