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Vibration-based damage detection in structuresAsnaashari, Erfan January 2014 (has links)
Structural health monitoring systems have a great potential for cost saving and safety improvement in different types of structures. One of the most important tasks of these systems is to identify damage at an early stage of its development. A variety of methods may be used to identify, locate, or quantify the extent of damage or fault in a structural or mechanical component. However, the preferable method is the one which maximises the probability of detecting the flaw, while also considering feasibility of in-situ testing, ease of use and economic factors. Cracks are one of the common defects in structural components that may ultimately lead to failure of structures if not detected. The presence of cracks in a structure brings about local variations in the stiffness of the structure. These variations cause the dynamic behaviour of the cracked structure to be different from that of a healthy one. Vibration-based damage detection methods have attracted considerable attention over the past few decades. These methods generally use changes to the physical properties of structures for the purpose of crack detection. In this thesis, two new vibration-based methods have been developed for damage detection in beam-like and rotor-type structures. The first method performs the entire signal processing required for crack detection in time domain. It is based on assessing the normality of vibration responses using the normal probability plot (NPP). The amount of deviation between the actual and normal distribution of measured vibration responses was calculated along the length of the structure to localise the crack. The second proposed method converts the vibration responses into frequency domain for further processing. Excitation of the cracked structure at a given frequency always generates higher harmonic components of the exciting frequency due to the breathing of the crack. This method uses the operational deflection shape of the structure at the exciting frequency and its higher harmonics to identify the crack location. Avoiding complicated signal processing in frequency domain is the main advantage of the first method. However, more precise identification of crack locations can be obtained through the second method. Generally, both methods have the advantage of being easy, reference-free and applicable to in-situ testing for any structure. The concept and computational approach of both methods along with their validations through numerical and experimental examples have been presented. Moreover, different input excitations have been used to evaluate the capability of the developed methods in detecting the crack location(s).
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Model-based clustering based on sparse finite Gaussian mixturesMalsiner-Walli, Gertraud, Frühwirth-Schnatter, Sylvia, Grün, Bettina January 2016 (has links) (PDF)
In the framework of Bayesian model-based clustering based on a finite mixture of Gaussian distributions, we present a joint approach to estimate the number of mixture components and identify cluster-relevant variables simultaneously as well as to obtain an identified model. Our approach consists in specifying sparse hierarchical priors on the mixture weights and component means. In a deliberately overfitting mixture model the sparse prior on the weights empties superfluous components during MCMC. A straightforward estimator for the true number of components is given by the most frequent number of non-empty components visited during MCMC sampling. Specifying a shrinkage prior, namely the normal gamma prior, on the component means leads to improved parameter estimates as well as identification of cluster-relevant variables. After estimating the mixture model using MCMC methods based on data augmentation and Gibbs sampling, an identified model is obtained by relabeling the MCMC output in the point process representation of the draws. This is performed using K-centroids cluster analysis based on the Mahalanobis distance. We evaluate our proposed strategy in a simulation setup with artificial data and by applying it to benchmark data sets. (authors' abstract)
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Die Relevanz der High Reliability Theory für Hochleistungssysteme : DiskussionspapierMistele, Peter 04 November 2005 (has links) (PDF)
Organisationen wie Feuerwehren, med. Rettungsdienste oder Spezialeinheiten der Polizei zeigen auch in Situationen, die durch Unsicherheit, unvollständige Informationen oder eine sehr hohe Dynamik gekennzeichnet sind, eine effiziente und effektive Leistungsfähigkeit. Sie können deswegen als Hochleistungssysteme (HLS) bezeichnet werden. Im vorliegenden Artikel wird dargestellt wie sich Erkenntnisse der High Reliabilty Theory auf die Untersuchung von Hochleistungssystemen auswirken und welche Gemeinsamkeiten und Parallelen bestehen. Dabei wird insbesondere ein Schwerpunkt auf die Thematik des Lernens gelegt.
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An Experimental Study of Heat Transfer Deterioration at Supercritical PressuresKline, Nathan January 2017 (has links)
Convective heat transfer to CO2 flowing upward in electrically heated vertical tubes at supercritical pressures was studied for wall heat fluxes q within ranges that included values corresponding to the onset of heat transfer deterioration (HTD). The inlet pressure was P = 8.35 MPa, the mass flux was in the range 200 kg/m2s ≤ G ≤ 1500 kg/m2s, and the inlet temperature was in the range 0 ◦C ≤ Tin ≤ 35 ◦C. Wall temperature measurements were collected in three tubular test sections, having inner diameters of D = 4.6, 8, and 22 mm. The abilities of three different HTD identification methods to separate the entire data set into deteriorated and normal heat transfer modes were tested. Two types of buoyancy parameters were tested as HTD detection methods, and correction factors for changes in mass flux were devised. The minimum heat flux at HTD onset was found to follow a power law of mass flux with the same exponent for all three sections and the same proportionality coefficient for the two smaller sections but a smaller one for the larger test section. For heat flux values that were larger than this minimum, HTD was found to occur only within a limited range of Tin, whose width increased with increasing heat flux. The heat transfer coefficient for normal heat transfer was expressed as an exponential function of the diameter.
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Bias and Precision of the Squared Canonical Correlation Coefficient under Nonnormal Data ConditionsLeach, Lesley Ann Freeny 08 1900 (has links)
This dissertation: (a) investigated the degree to which the squared canonical correlation coefficient is biased in multivariate nonnormal distributions and (b) identified formulae that adjust the squared canonical correlation coefficient (Rc2) such that it most closely approximates the true population effect under normal and nonnormal data conditions. Five conditions were manipulated in a fully-crossed design to determine the degree of bias associated with Rc2:
distribution shape, variable sets, sample size to variable ratios, and within- and between-set correlations.
Very few of the condition combinations produced acceptable amounts of bias in Rc2, but those that did were all found with first function results. The sample size to variable ratio (n:v)was determined to have the greatest impact on the bias associated with the Rc2 for the first, second, and third functions. The variable set condition also affected the accuracy of Rc2, but for the second and third functions only. The kurtosis levels of the marginal distributions (b2), and the
between- and within-set correlations demonstrated little or no impact on the bias associated with Rc2. Therefore, it is recommended that researchers use n:v ratios of at least 10:1 in canonical analyses, although greater n:v ratios have the potential to produce even less bias. Furthermore,because it was determined that b2 did not impact the accuracy of Rc2, one can be somewhat confident that, with marginal distributions possessing homogenous kurtosis levels ranging
anywhere from -1 to 8, Rc2 will likely be as accurate as that resulting from a normal distribution.
Because the majority of Rc2 estimates were extremely biased, it is recommended that all Rc2 effects, regardless of which function from which they result, be adjusted using an appropriate adjustment formula. If no rationale exists for the use of another formula, the Rozeboom-2 would likely be a safe choice given that it produced the greatest number of unbiased Rc2 estimates for the greatest number of condition combinations in this study.
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Inferences about Parameters of Trivariate Normal Distribution with Missing DataWang, Xing 05 July 2013 (has links)
Multivariate normal distribution is commonly encountered in any field, a frequent issue is the missing values in practice. The purpose of this research was to estimate the parameters in three-dimensional covariance permutation-symmetric normal distribution with complete data and all possible patterns of incomplete data. In this study, MLE with missing data were derived, and the properties of the MLE as well as the sampling distributions were obtained. A Monte Carlo simulation study was used to evaluate the performance of the considered estimators for both cases when ρ was known and unknown. All results indicated that, compared to estimators in the case of omitting observations with missing data, the estimators derived in this article led to better performance. Furthermore, when ρ was unknown, using the estimate of ρ would lead to the same conclusion.
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Que saudade da professorinha: história e memória da escolarização das normalistas Niteroienses e RecifensesFIGUEIRÔA, Ana Paula Rodrigues 31 July 2017 (has links)
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Previous issue date: 2017-07-31 / CAPES / Esta tese tem como objetivo compreender os ensejos que expressaram, em meados do século XX, a implantação do Ensino Normal em Niterói/RJ e em Recife/PE para a formação de professores, expondo uma contribuição expressiva para a história das instituições de Ensino Normal do Brasil, responsáveis pela formação de mestres das primeiras letras. As instituições pesquisadas são: École Normale Supérieure de Paris/França; Escola Normal do Município da Côrte, em Niterói/Rio de Janeiro; e as Escolas Normais do Recife: Escola Normal Oficial de Pernambuco e a Escola Normal Pinto Júnior da Sociedade Propagadora. O método de pesquisa utilizado foi a história oral, pautada nas entrevistas e subsidiado pela coleta documental. Ressalte-se que as Normalistas entrevistadas foram as do Brasil e que a escola francesa propiciou o embasamento da gênese do Ensino Normal no Brasil. Este estudo está dividido em cinco capítulos: o primeiro é intitulado de Introdução, demonstrando a base metodológica e a produção do conhecimento sobre a temática; o segundo capítulo tem como denominação: Edificando o cenário das Escolas Normais, demonstrando a historicidade da criação das referidas Escolas Normais; o terceiro capítulo tem como título: A Inserção das mulheres na educação niteroiense e recifense, demonstrando o universo das três instituições brasileiras estudadas; já o quarto capítulo, Tecendo o saber: os cortes e recortes na memória das Normalistas, discorre sobre a análise das categorias: gênero, família, educação e vida profissional; o quinto capítulo, são as considerações finais, quando exibimos as reflexões sobre todo o estudo, permitindo assim reconstituir parte da história e memória das Normalistas e suas conquistas, desde o seu ingresso no Curso Normal até a sua profissionalização. / Cette thèse a pour objectif de comprendre les attentes suscitées, au cours de XXe siècle, par l’Enseignement Normal à Niterói (Rio de Janeiro) et à Recife (Pernambouc) pour la formation des instituteurs, et d’apporter un contribution expressive à l’histoire des institutions de l’Enseignement Normal au Brésil, responsable de la formation des maîtres des écoles primaires. L’étude porte sur les institutions suivantes: l’École Normale Supérieure de Paris, l’École Normale de la commune de la Côrte, à Niterói (Rio de Janeiro), ainsi que les Écoles Normales de Recife: l’École Normale Officielle du Pernambouc et l’École Normal Pinto Júnior de la « Société Propagatrice de l’Instruction Publique ». La méthode utilisée est l’histoire orale sur la base d’entretiens appuyés par la collecte de documents. Il convient de préciser que les Normaliens interrogés sont ceux du Brésil, et que l’école française a servi de base à la génèse de l’Enseignement Normal au Brésil. Cette étude se divise en cinq chapîtres: le premier est intitulé : ‘‘Introduction, démonstration de la base méthodologique et la production de connaissances sur le thème’’; le second chapître s’intitule: ‘‘L’édification du cadre des Écoles Normales, demonstration de l’historicité de la créations desdites Écoles Normales’’; le troisième chapître a pour titre: ‘‘L’insertion des femmes dans l’éducation à Niteroi et à Recife, démonstration de l’univers des trois institutions brésiliennes étudiées’’ ; le quatrième chapître, ‘‘Tisser le savoir: les coupes et découpes dans la mémoire des Normaliens’’, se penche sur l’analyse des catégories: genre, famille, éducation et vie professionnelle; le cinquième chapître, est celui des considérations finales, le moment d’exposer nos réflexions sur l’étude, afin de permettre la reconstruction d’une partie de l’histoire et de la mémoire des Normaliens, ainsi que de leurs conquêtes, depuis leur entrée au Cours Normal jusqu’à leur professionalisation. / This thesis aims to understand the opportunities that, in the middle of the 20th century, expressed the implantation of Normal Teaching in Niterói / RJ and Recife / PE for the graduation of teachers, exposing a significant contribution to the history of institutions of Normal Teaching of Brazil, responsible for the graduation of masters of the first letters. The institutions researched are: École Normale Supérieure de Paris/França; Escola Normal do Município da Côrte, em Niterói/Rio de Janeiro; and the Normal Schools of Recife: Escola Normal Oficial de Pernambuco e a Escola Normal Pinto Júnior da Sociedade Propagadora. The research method used was the oral history, based on the interviews and subsidized by the gathering of documents. It should be noted that the Normalists interviewed were those of Brazil and that the French school provided the basis for the genesis of Normal Education in Brazil. This study is divided into five chapters: the first is titled Introduction, demonstrating the methodological basis and the production of knowledge on the subject; the second chapter has as denomination: Building the scenery of the Normal Schools, demonstrating the historicity of the creation of said Normal Schools; the third chapter is entitled: The insertion of women in Niterói and Recife education, demonstrating the universe of the three Brazilian institutions studied; the fourth chapter, Weaving the knowledge: the cuts and cutouts in the memory of the Normalists, discusses the analysis of categories: gender, family, education and professional life; the fifth chapter, are the final considerations, when is presented the reflections about the whole study, thus allowing to reconstitute part of the history and memory of the Normalists and their conquests, from their entrance in the Normal Course until their professionalization. / Esta tesis tiene como objetivo comprender las enseñanzas que expresaron, a mediados del siglo XX, la implantación de la Educación Normal en Nireói/RJ y en Recife/PE para la formación de profesores, exponiendo una contribución expresiva para la historia de las instituciones de Educación Normal de Brasil, responsables por la formación de maestros de las primeras letras. Las instituciones investigadas son: Escuela Normal Superior de Paris/Francia; Escuela Normal Superior del Municipio de la Corte, en Niterói/Rio de Janeiro; y las Escuelas Normales de Recife: Escuela Normal Oficial de Pernambuco y la Escuela Normal Pinto Junior de la Sociedad Propagadora. El método de investigación utilizado fue la historia oral, pautada en las entrevistas y subsidiada por la recolección de documentos. Resáltese que los Normalistas entrevistados fueron de Brasil y que la escuela francesa propició el fundamento de la génesis de la Educación Normal en Brasil. Este estudio está dividido en cinco capítulos: El primero se titula de introducción, demostrando la base metodológica y la producción de conocimiento sobre la temática; el segundo capítulo tiene como denominación: Edificando el Escenario de las Escuelas Normales, demostrando la historia de la creación de las referidas Escuelas Normales; el tercer capítulo tiene como título: La inmersión de las mujeres en la educación niteroiense y recifense, demostrando el universo de las tres instituciones brasileras estudiadas; ya el cuarto capítulo, Tejiendo el saber: los cortes y recortes en la memoria de los Normalistas, discurre sobre el análisis de las categorías: género, familia, educación y vida profesional; el quinto capítulo, son las consideración finales, cuando exhibimos las reflexiones sobre el estudio, permitiendo reconstruir parte de la historia y memoria de los Normalistas y sus conquistas, desde su ingreso en el Curso Normal hasta su profesionalización .
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r-critical points and Taylor expansion of the exponential map, for smooth immersions in Rk+nGarcía Monera, María 29 May 2015 (has links)
[EN] Classically, the study of the contact with hyperplanes and hyperspheres has been realized by using the family of height and distance squared functions. On the first part of the thesis, we analyze the Taylor expansion of the exponential map up to order three of a submanifold $M$
immersed in $\r n.$ Our main goal is to show its usefulness for the description of special contacts of the submanifolds with geometrical models.
As we analyze the contacts of high order, the complexity of the calculations increases. In this work, through the Taylor expansion of the exponential map, we characterize the geometry of order
higher than $3$ in terms of invariants of the immersion, so that the effective computations in specific cases become more affordable. It allows also to get new geometric insights.
On the second part of the thesis, we introduce the concept of critical point of a smooth map between submanifolds. If we consider a differentiable $k$-dimensional manifold $M$
immersed in $\r{k+n},$ we know that its focal set can also be
interpreted as the image of the critical points of the {\it normal
map} $\nu(m,u): NM\to \r{k+n}$ defined by $\nu(m,u)=\pi_N(m,u)+
u,$ for $m\in M$ and $u\in N_mM,$ where $\pi_N:NM\to M$ denotes the normal
bundle.
In the same way, the parabolic set of a differential submanifold is given through the analysis of the singularities of the height functions over the submanifold. If we consider a differentiable
$k$-dimensional manifold $M$ immersed in $\r{k+n},$ we know that its parabolic set can also be interpreted as the image of the critical points of the {\it generalized Gauss map} $\psi(m,u):
NM\to \r{k+n}$ defined by $\psi(m,u)= u,$ for $u\in N_mM.$
Finally, we characterize the asymptotic directions as the tangent set of a $k$-dimensional manifold $M$ immersed in $\r{k+n}$ throughout the study of the singularities of the tangent map $\Omega(m,y): TM\to \r{k+n}$ defined by $\Omega(m,y)=\pi(m,y)+y,$
for $y\in T_mM,$ where $\pi:TM\to M$ denotes the tangent bundle.
We describe first the focal set and its geometrical relation to the Veronese of curvature for
$k$-dimensional immersions in $\r{k+n}.$ Then we define the $r$-critical points of a differential map $f:H \to K$ between two differential manifolds and characterize the $2$ and $3$-critical points of the normal map and generalized Gauss map. The number of these
critical points at $m\in M$ may depend on the degeneration of the curvature ellipse and we calculate those numbers in the particular
case that $M$ is an immersed surface in $\r{4}$ for the normal map and $\r{5}$ for the generalized Gauss map. / [ES] En general, el estudio del contacto con hiperplanos e hiperesferas se ha llevado a cabo usando la familia de funciones altura y la función distancia al cuadrado. En la primera parte de la tesis analizamos el desarrollo de Taylor de la aplicación exponencial hasta orden 3 de una subvariedad $M$ inmersa en $\r n.$ Nuestro principal objetivo es mostrar su utilidad en el estudio de contactos especiales de subvariedades con modelos geométricos.
A medida que analizamos los contactos de orden mayor, la complejidad de las cuentas aumenta.
En este trabajo, a través del desarrollo de Taylor de la aplicación exponencial, caracterizamos la geometría de orden mayor que $3$ en términos de invariantes geométricos de la inmersión, por lo que el trabajo con las cuentas en casos especiales se convierte en más manejable. Esto nos permite también obtener nuevos resultados geométricos.
En la segunda parte de la tesis se introduce el concepto de punto crítico de una aplicación regular entre subvariedades. Si consideramos una variedad diferenciable $M$ de dimensión $k$ e inmersa en $\r{k+n},$ sabemos que su conjunto focal puede ser interpretado como la imagen de los puntos críticos de la {\it aplicación normal} $\nu(m,u): NM\to \r{k+n}$ definida por $\nu(m,u)=\pi_N(m,u)+
u,$ para $m\in M$ y $u\in N_mM,$ donde $\pi_N:NM\to M$ denota el fibrado normal.
De la misma manera, el conjunto parabólico de una subvariedad diferencial viene dado por el análisis de las singularidades de la función altura sobre la subvariedad.
Si consideramos una subvariedad $M$ de dimensión $k$ e inmersa en
$\r{k+n},$ sabemos que su conjunto parabólico puede ser interpretado como la imagen de los puntos críticos de la {\it aplicación generalizada de Gauss} $\psi(m,u): NM\to \r{k+n}$ definida por $\psi(m,u)= u,$ donde $u\in N_mM.$
Finalmente, caracterizamos las direcciones asintóticas como el conjunto de direcciones del tangente de una subvariedad $M$ de dimensión $k$ e inmersa en
$\r{k+n}$ a través del estudio de las singularidades de la aplicación tangente
$\Omega(m,y): TM\to \r{k+n}$ definida por $\Omega(m,y)=\pi(m,y)+y,$
para $y\in T_mM,$ donde $\pi:TM\to M$ denota el fibrado tangente.
Describimos primero el conjunto focal y su relación geométrica con la Veronese de curvatura para una variedad $k$ dimensional inmersa en $\r{k+n}.$ Entonces, definimos los puntos $r$-críticos de una aplicación $f:H \to K$ entre dos subvariedades y caracterizamos los puntos $2$ y $3$ críticos de la aplicación normal y la aplicación generalizada de Gauss. El número de estos puntos críticos en $m\in M$ depende de la degeneración de la elipse de curvatura y calculamos ese número en el caso particular de una superficie inmersa en $\r{4}$ para la aplicación normal y $\r{5}$ para la aplicación generalizada de Gauss. / [CAT] En general, l'estudi del contacte amb hiperplans i hiperesferes s'ha dut a terme utilitzant la família de funcions altura i la funció distància al quadrat. A la primera part de la tesi analitzem el desenvolupament de Taylor de l'aplicació exponencial fins a ordre 3 d'una subvarietat $M$ immersa en $\r n.$ El nostre principal objectiu és mostrar la seua utilitat en l'estudi de contactes especials de subvarietats amb models geomètrics.
A mesura que analitzem els contactes d'ordre major, la complexitat dels comptes augmenta.
En aquest treball, a través del desenvolupament de Taylor de l'aplicació exponencial, caracteritzem la geometria d'ordre major que $ 3 $ en termes d'invariants geomètrics de la immersió, de manera que el treball amb els comptes en casos especials es converteix en més manejable.
Això ens permet també obtenir nous resultats geomètrics.
A la segona part de la tesi s'introdueix el concepte de punt crític d'una aplicació regular entre subvarietats. Si considerem una varietat diferenciable $ M $ de dimensió $ k $ i immersa en
$ \r {k + n}, $ sabem que el seu conjunt focal pot ser interpretat com la imatge dels punts crítics de la {\it aplicació normal} $ \nu (m, u): NM \to \r {k + n} $ definida per $ \nu (m, u) = \pi_N (m, u) +
o, $ per $ m \in M $ i $ u \in N_mM, $ on $ \pi_N: NM \to M $ denota el fibrat normal.
De la mateixa manera, el conjunt parabòlic d'una subvarietat diferencial ve donat per l'anàlisi
de les singularitats de la funció altura sobre la subvarietat.
Si considerem una subvarietat $ M $ de dimensió $ k $ i immersa en
$ \r {k + n}, $ sabem que el seu conjunt parabòlic pot ser interpretat com la imatge dels punts crítics de la {\it aplicació generalitzada de Gauss} $ \psi (m, u): NM \to \r{k + n} $ definida per $ \psi (m, u) = u, $ on $ u \in N_mM. $
Finalment, caracteritzem les direccions asimptòtiques com el conjunt de direccions del tangent d'una subvarietat $ M $ de dimensió $ k $ i immersa en $ \r{k + n} $ a través de l'estudi de les singularitats de l'aplicació tangent $ \Omega (m, y): TM \to \r {k + n} $ definida per $ \Omega (m, y) = \pi (m, y) + y, $
per $ y \in T_mM, $ on $ \pi: TM \to M $ denota el fibrat tangent.
Descrivim primer el conjunt focal i la seva relació geomètrica amb la Veronese de curvatura per a una varietat $ k $ dimensional immersa en $ \r{k + n}. $ Llavors, definim els punts $ r $-crítics d'una aplicació $ f: H \to K $ entre dues subvarietats i caracteritzem els punts $ 2 $ i $ 3 $ crítics de l'aplicació normal i l'aplicació generalitzada de Gauss. El nombre d'aquests punts crítics en
$ m \in M $ depèn de la degeneració de l'el·lipse de curvatura i calculem aquest nombre en el cas particular d'una superfície immersa en $ \r{4} $ per a l'aplicació normal i $ \r{5} $ per a l'aplicació generalitzada de Gauss. / García Monera, M. (2015). r-critical points and Taylor expansion of the exponential map, for smooth immersions in Rk+n [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/50935 / TESIS
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Our Shared Storm: Exploring Five Scenarios of Climate Fiction FuturesJanuary 2020 (has links)
abstract: This project uses the tools of speculative climate fiction to explore and imagine the future of the United Nations climate negotiations in each of the five Shared Socioeconomic Pathway (SSP) scenarios. Climate fiction (cli-fi) proves a powerful but imperfect tool for envisioning future challenging and turning scientific models into meaningful narratives. / Dissertation/Thesis / Masters Thesis Sustainability 2020
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Differentiating between healthy control participants and those with mild cognitive impairment using volumetric MRI dataDeVivo, Renee 11 July 2018 (has links)
OBJECTIVE: To determine whether volumetric measures of the hippocampus or entorhinal cortex in combination with other cortical measures can differentiate between cognitively normal individuals and participants with amnestic mild cognitive impairment (MCI).
METHODS: T1-weighted magnetic resonance imaging (MRI) data acquired from 46 cognitively normal participants and 50 participants with amnestic MCI as part of the Boston University Alzheimer's Disease Center research registry and the Alzheimer's Disease Neuroimaging Initiative were used in this cross-sectional study. Cortical and subcortical volumes, including hippocampal subfield volumes, were automatically generated from each participant’s structural MRI data using FreeSurfer v6.0. Nominal logistic regression models containing these variables were used to evaluate their ability to identify participants with MCI.
RESULTS: A model containing 11 regions of interest (insula, superior parietal cortex, rostral middle frontal cortex, middle temporal cortex, pars opercularis, paracentral lobule, whole hippocampus, subiculum, superior temporal cortex, precentral cortex and caudal anterior cingulate cortex) fit the data best (R2 = 0.7710, whole model test chi square = 102.4794, p < 0.0001).
CONCLUSIONS: Volumetric measures acquired from MRI were able to correctly identify most healthy control subjects and those with amnestic MCI using measures of selected medial temporal lobe structures in combination with those from other cortical areas yielding an overall classification of 95.83% for this dataset. These findings support the notion that while clinical features of amnestic MCI may reflect medial temporal atrophy, differences that can be used to distinguish between these two populations are present elsewhere in the brain. This finding further affirming that atrophy can be identified before clinical features are expressed. Additional studies are needed to assess how well other imaging modalities, such as resting state functional connectivity, diffusion imaging, and amyloid and tau position emission tomography (PET), perform in classifying participants who are cognitively normal versus those who are amnestic MCI.
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