• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 50
  • 23
  • 8
  • 6
  • 4
  • 3
  • 2
  • 2
  • 2
  • 2
  • 2
  • 1
  • 1
  • 1
  • Tagged with
  • 134
  • 22
  • 20
  • 18
  • 12
  • 11
  • 10
  • 10
  • 10
  • 10
  • 9
  • 9
  • 8
  • 8
  • 8
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
71

Abilities and Disabilities—Applying Machine Learning to Disentangle the Role of Intelligence in Diagnosing Autism Spectrum Disorders

Wolff, Nicole, Eberlein, Matthias, Stroth, Sanna, Poustka, Luise, Roepke, Stefan, Kamp-Becker, Inge, Roessner, Veit 22 April 2024 (has links)
Objective: Although autism spectrum disorder (ASD) is a relatively common, well-known but heterogeneous neuropsychiatric disorder, specific knowledge about characteristics of this heterogeneity is scarce. There is consensus that IQ contributes to this heterogeneity as well as complicates diagnostics and treatment planning. In this study, we assessed the accuracy of the Autism Diagnostic Observation Schedule (ADOS/2) in the whole and IQ-defined subsamples, and analyzed if the ADOS/2 accuracy may be increased by the application of machine learning (ML) algorithms that processed additional information including the IQ level. Methods: The study included 1,084 individuals: 440 individuals with ASD (with a mean IQ level of 3.3 ± 1.5) and 644 individuals without ASD (with a mean IQ level of 3.2 ± 1.2). We applied and analyzed Random Forest (RF) and Decision Tree (DT) to the ADOS/2 data, compared their accuracy to ADOS/2 cutoff algorithms, and examined most relevant items to distinguish between ASD and Non-ASD. In sum, we included 49 individual features, independently of the applied ADOS module. Results: In DT analyses, we observed that for the decision ASD/Non-ASD, solely one to four items are sufficient to differentiate between groups with high accuracy. In addition, in sub-cohorts of individuals with (a) below (IQ level ≥4)/ID and (b) above average intelligence (IQ level ≤ 2), the ADOS/2 cutoff showed reduced accuracy. This reduced accuracy results in (a) a three times higher risk of false-positive diagnoses or (b) a 1.7 higher risk for false-negative diagnoses; both errors could be significantly decreased by the application of the alternative ML algorithms. Conclusions: Using ML algorithms showed that a small set of ADOS/2 items could help clinicians to more accurately detect ASD in clinical practice across all IQ levels and to increase diagnostic accuracy especially in individuals with below and above average IQ level.
72

Optimering av en planetväxel genom användning av ett aktivt balanseringssystem / Optimizing a planetary gear train using an active balancing mechanism

Eng Stensson, Alexander, Olsson, Martin January 2017 (has links)
Arbetets syfte är att undersöka hur en planetväxel kan optimeras med avseende på kostnad och momentöverföringskapacitet då det konceptuella balanseringssystemet skapat av Swepart Transmission AB appliceras på en planetväxel. Arbetet undersöker även huruvida höghållfasta stål kan användas för att optimera en planetväxel ytterligare. Planetväxlarna i detta arbete genererades i programvaran KISSsoft och 3D-modeller av dessa planetväxlar skapades i SolidWorks. Olika tillverkningsfel introducerades i en planetväxel och dess inverkan på lastfördelningen mellan planethjulen samt balanseringsystemets förmåga att reducera dessa fel undersöktes med hjälp av programvaran MSC Adams. Resultatet från undersökningarna i MSC Adams användes sedan för att optimera planetväxlarna. För planetväxlarna utfördes slutligen en mass- och kostnadsjämförelse för att undersöka hur konkurrenskraftig en planetväxel med Sweparts balanseringssystemet är jämfört med dagens konventionella planetväxlar.
73

Le sentiment de compétence, modérateur du lien entre le QI et la performance scolaire

Leclerc, Myriam January 2008 (has links)
Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.
74

The Quantitative Genetics of Neurodevelopment: A Magnetic Resonance Imaging Study of Childhood and Adolescence

Schmitt, James Eric 01 January 2007 (has links)
Understanding the causes of individual differences in brain structure may give clues about the etiology of cognition, personality, and psychopathology, and also may identify endophenotypes for molecular genetic studies on brain development. We performed a comprehensive statistical genetic study of anatomic neuroimaging data from a large pediatric sample (N=600+) of twins and family members from the Child Psychiatry Branch at the NIMH. These analyses included variance decomposition of structural volumetric endophenotypes at several levels of resolution, voxel-level analysis of cortical thickness, assessment of gene by age interaction, several multivariate genetic analyses, and a search for genetically-mediated brain-behavioral relationships. These analyses found strong evidence for a genetic role in the generation of individual differences in brain volumes, with the exception of the cerebellum and the lateral ventricles. Subsequent multivariate analyses demonstrated that most of the genetic variance in large volumes shares a common source. More subtle analyses suggest that although this global genetic factor is the principal determinant of neuroanatomic variability, genetic factors also mediate regional variability in cortical thickness and are different for gray and white matter volumes. Models using graph theory show that brain structure follows small-world architectural rules, and that these relationships are genetically-determined. Structural homologues appeared to be strongly related genetically, which was further confirmed using novel methods for semi-multivariate quantitative genetic analysis at the voxel level. Studies on interactions with age were mixed. We found evidence of gene by age interaction on frontal and temporal lobar volumes, indicating that the role of genetic factors on these structures is dynamic during childhood. Analyses on cortical thickness at a finer scale, however, showed that environmental factors are more important in childhood, and environmental changes were responsible for most of the changes in heritability over this age range. When assessing the relationship between brain and behavior, we found weak negative genetic correlations and positive environmental correlations between IQ and cortical thickness, which appear to partially cancel each other out. More complex models allowing for age interactions suggest that high and low IQ groups have different patterns of gene by age interactions in concordance with prior literature on cortical phenotypes.
75

Contribution à l'identification de nouveaux gènes impliqués dans la Déficience intellectuelle liée au Sexe(X-LID) par séquençage à haut débit de l’exome du chromosome X avec la technologie SOLiD / Contribution to the identification of new genes involved in X-Linked Intellectual Deficiency using SOLiD Next Generation Sequencing technique applied to X exome

Bouazzi, Habib 24 March 2016 (has links)
La Déficience Intellectuelle liée au chromosome X (X-LID), anciennement appelée RMLX (retard mental lié au chromosome X) est une pathologie fréquente (3 % de la population) et handicapante. Cette déficience se manifeste par la réduction de la capacité à comprendre les informations nouvelles ou complexes, des difficultés d’acquisition de nouvelles compétences et l’échec dans la gestion de sa vie en toute autonomie ; celle-ci est souvent accompagnée par un dysmorphisme corporel. Cette pathologie s’installe dès l’enfance (avant l'âge de 18 ans) et a des répercussions sur le développement de l’individu (QI<70). La pathogénie de la déficience intellectuelle reste obscure et dans 50 % des cas, la cause n’est pas connue. Dix pour-cent (10 %) des cas de la déficience intellectuelle seraient liés à des gènes localisés sur le chromosome X, avec une mutation transmise par les mères et affectant principalement les garçons. Parmi les 931 gènes du chromosome X, seulement 114 gènes ont été identifiés comme gènes de déficience intellectuelle. Le dernier (le gène SSR4) fut caractérisé en mars 2014. À l’heure des technologies du séquençage de haut débit, le laboratoire de génétique moléculaire de l’hôpital Necker de Paris s'est doté d’une plateforme d’identification de mutation génétique humaine par séquençage à haut débit permettant le diagnostic des maladies rares. L’objectif de mon travail de thèse était d’appliquer l’approche du séquençage à très haut débit (technique SOLiD) dans l’identification de nouveaux gènes de la déficience intellectuelle liée au chromosome X chez des familles ayant des garçons atteints de déficience intellectuelle non-syndromique, d’identifier les mutations des gènes qui sont déjà connus et d’en discuter la corrélation génotype-phénotype. L’approche que j’ai utilisée dans cette étude est le diagnostic génétique par séquençage à haut débit de l’exome du chromosome X de vingt sujets appartenant à dix familles (X-LID) françaises. La procédure consiste à capturer l’exome du chromosome X des patients atteints, à l’enrichir par la technologie Rain-Dance, puis à le séquencer dans notre plateforme avec un séquenceur à haut débit de la technologie SOLiD5500 afin d’analyser les résultats et pour ne retenir que les nouvelles mutations et commenter leur pouvoir pathogène. Cette étude a mis en évidence de nouvelles mutations dans 21 gènes, dont neuf gènes ne sont pas encore décrits parmi les gènes X-LID et a révélé l’importance de l’hétérogénéité génétique tout en relevant la possibilité de l’effet des charges mutationnelles et le rôle gènes modificateurs. Certaines nouvelles mutations, nous les avons identifiées dans des gènes connus pour leur implication dans la déficience intellectuelle et les avons publiées durant les études doctorales. Pour confirmer la causalité des nouveaux gènes ayant muté chez les familles atteintes, des études fonctionnelles supplémentaires in vivo doivent être appliquées tout en suivant les publications sur le même sujet afin de comparer avec des cas similaires. / X linked Intellectual deficiency (X - LID); formerly X-LMR (X Linked Mental Retardation) is a common pathology (3 % of the population). Intellectual Deficiency (ID) is the most frequent cause of serious handicap in children and young adults. Defining features of ID include an overall intelligence quotient (IQ) of less than 70 together with associated functional deficits in adaptive behavior (such as daily living, social and communication skills), which manifest before18 years of age. ID pathogenesis remains obscure and 50% of cases have no known cause. Ten percent of the intellectual intellectual deficiency would be related to genes located on the X chromosome, and subsequently inherited by affected boys. Among the 931 genes of the X chromosome, only 114 genes have been identified as X-LID genes. The last (SSR4 gene) was characterized in March 2014. At the time of the Next Generation Sequencing (NGS), the laboratory of molecular genetics of Necker hospital in Paris is equipped with a platform for the identification of human genetic mutation by high-throughput sequencing for the diagnosis of rare diseases. The objective of my thesis work was to seek new genes for X linked intellectual deficiency in families with non-syndromes cognitive disorder affected boys and to identify mutations in the genes that are already known and to discuss the genotype, phenotype correlation. The approach that I have used in this study is genetic diagnosis by high-throughput sequencing of chromosome X exomes of 20 subjects belonging to ten X-LID French families. The procedure is to capture and enrich the exome of the X chromosome of patients, then to sequence it in our platform with a high throughput sequencer of SOLid technology then analyze the results and retain that new mutations to discuss their pathogenity. This study has highlighted new mutations in 21 genes, including nine that are not yet described among the X-LID genes. Some new mutations, we identified in genes known through their involvement in cognitive impairment were published during my doctoral studies. To confirm causality of new genes that were found mutated in families, additional studies in vivo must be applied while following the literature to make comparisons with similar cases.
76

Trauma na infância e desempenho cognitivo : prejuízo da atenção em crianças em idade escolar

Bücker, Joana January 2010 (has links)
CONTEXTO: A exposição a eventos traumáticos durante a infância está associada a uma piora das funções cognitivas, especialmente na função executiva. Estes achados são bem documentados em adultos. Entretanto há poucos estudos que avaliam as alterações cognitivas em crianças em idade escolar com história de trauma precoce. OBJETIVO: Avaliar o desempenho cognitivo em crianças com história de abuso sexual, maus-tratos e/ou negligência, em comparação a controles não expostos a vivências traumáticas. MÉTODO: Em um estudo de caso-controle, foram recrutadas 30 crianças de 5 a 12 anos de idade com história de trauma e 30 controles, pareados por sexo e idade, no período de outubro de 2008 a janeiro de 2010. A cognição foi avaliada através do teste ‗Wisconsin card sorting test’, Escala Wechsler de Inteligência – 3ª Edição (subtestes dígitos, cubos e vocabulário) e do teste ‗Continuos Performance Test‘. O K-SADS-E foi utilizado para identificar sintomas ou transtornos psiquiátricos de acordo com DSM-IV-TR, os quais eram confirmados também em entrevista com psiquiatra. RESULTADOS: A prevalência de sintomas psiquiátricos nas crianças com trauma foi de 56,6% e nos controles foi de 6,7 % (p<0.001). Os casos tiveram um pior desempenho no subteste ‘Dígitos do WISC-III’ (F=8,553, p=0,005) e no teste ‗CPT commission errors‘ (F=5.63, p=0.022) quando comparados aos controles. Em crianças com trauma, o QI foi estatisticamente superior naquelas sem sintomas psiquiátricos (p= 0,025) em comparação com aquelas que apresentavam sintomas. CONCLUSÕES: Os resultados sugerem que crianças com história de trauma apresentam prejuízo na atenção e na memória de trabalho comparado a controles, o que pode ser detectado já nos primeiros anos da idade escolar. A presença de sintomas psiquiátricos também está associada a um pior funcionamento cognitivo nestas crianças e a um pior funcionamento global. Os dados apresentados reforçam a importância de intervenção precoce para prevenir déficit cognitivo quando o trauma não pode ser evitado. / INTRODUCTION: Exposure to traumatic events during childhood is often associated with cognitive impairment. These findings are well documented in adults. However, few studies have examined cognitive function in school-age children with a history of early trauma. OBJECTIVE: To examine cognitive performance in children with trauma compared to age and gender matched controls. METHODS: We recruited thirty 5-12 years old children with a history childhood trauma and thirty age and gender matched controls. The neuropsychological battery assessed broad cognitive domains such as learning/working memory, executive function, attention, verbal/premorbid intellectual functioning (IQ) and impulsivity. The K-SADS-E was used to examine psychiatric symptoms or disorders according to DSM-IV-TR, which were also confirmed in an interview with a psychiatrist. RESULTS: The prevalence of psychiatric symptoms in those with childhood trauma was 56.6% while in controls was 6.7% (p <0.001). Those with trauma showed a worse performance in the Digit Span WISC-III (F = 8.553, p = 0.005) and CPT errors (F=5.63, p=0.022) when compared to controls. In addition, children with psychiatric symptoms and childhood trauma, showed lower IQ scores when compared to those without (p = 0.025). CONCLUSIONS: The results suggest that children with trauma show attention and working memory impairment when compared to controls, which is present as early as in the first school years. Furthermore, there is a high prevalence of psychiatric symptoms in children exposed to traumatic experiences and this seems to be associated with worse cognitive performance and global functioning. These findings further support the need for early intervention to prevent cognitive impairment when childhood trauma could not be avoided.
77

An Examination of the Validity and Usefulness of The Video Suggestibility Scale For Children.

McFarlane, Felicity Jane, kimg@deakin.edu.au January 2000 (has links)
The Video Suggestibility Scale for Children (VSSC) was developed by Scullin and colleagues (Scullin & Ceci, 2000; Scullin & Hembrooke, 1998) as a tool for discriminating between children who have different levels of suggestibility. The scale requires children to view a 5-minute video about a birthday party, and to subsequently participate in an interview consisting of 18 yes/no questions. The VSSC consists of two main subscales; Yield (a measure of children's willingness to respond affirmatively to misleading questions about the video) and Shift (a measure of the children's tendency to change their responses after negative feedback from the interviewer). Preliminary research by Scullin and colleagues suggested that the scale possesses satisfactory internal consistency and that children's scores on the VSSC can predict their performance in another suggestibility paradigm. This thesis presents two studies, which further examine the validity and usefulness of the VSSC in an Australian sample of 3- to-5-year-old children. In Study One, children's performance on the VSSC (N = 77) was compared to their performance using other measures of suggestibility. These measures included children's willingness to assent to a false event as well as the number of false interviewer suggestions and new false details that the children provided in their accounts about an independent true-biased and an independent false (non-experienced) event. An independent samples t-test revealed that those children who assented to the false activity generated higher scores on the Yield measure. This pattern was also observed for the Shift subscale although it was not significant. Hierarchical regression analyses revealed that Yield was a significant predictor of the number of false details reported about the false activity, but not the true-biased activity. There was no significant relationship between the Shift Vlll subscale and any of the dependent variables. Overall this study provided partial support for the construct validity of the VSSC. However, it indicated that children's performance on this scale may not be generalisable across different contexts and interview paradigms, and that the Yield subscale is more generalisable than the Shift subscale. Study Two examined whether various group and individual factors that have previously been shown to relate suggestibility (i.e., age, IQ, memory, socio-economic status, gender, temperament) could predict suggestibility as measured by the VSSC. Two hundred and twenty children were recruited from kindergartens, and were divided into two broad socio-economic categories (based predominantly on income). Hierarchical regression analyses revealed that age, intelligence and memory inversely predicted children's Yield suggestibility. Further, children of low socio-economic backgrounds were more suggestible than children of high socio-economic background, and boys were more suggestible than girls on the Yield measure. Although shyness and other internalised and externalised characteristics were explored, no reliable significant relationships were found with Yield. With regard to the Shift subscale, no reliable relationships were found for any of the independent variables except for SES. Overall, results of Study 2 indicated that the VSSC is a potentially useful measure for discriminating between children's suggestibility on the basis on their individual characteristics, although benefits were observed mainly in relation to the Yield subscale. With reference to the findings of these two studies, the potential contribution of the VSSC for research and applied forensic contexts was discussed.
78

Transposition de fréquence et compensation du déséquilibre IQ pour des systèmes multiporteuses sur canal sélectif en fréquence

Traverso, Sylvain 16 November 2007 (has links) (PDF)
L'objectif de cette thèse est de proposer des solutions pour améliorer les performances des transmissions des terminaux mobiles à haut débits, faibles coûts et faible consommation. En effet, l'augmentation des débits implique que les canaux de transmission soient de plus en plus difficiles, rendant la tâche des récepteurs plus ardue. Nous nous intéressons aux systèmes MultiBandes OFDM car ils soumettent la porteuse à un algorithme de saut de fréquence, et permettent ainsi de disposer d'une grande diversité fréquentielle. Dans ce contexte, nous proposons dans une première partie des égaliseurs de canaux optimaux au sens des moindres carrés tirant profit de la diversité fréquentielle afin d'améliorer d'une manière significative les performances des systèmes<br>OFDM pour des canaux très difficiles. Dans la seconde partie de ce travail, nous proposons un synthétiseur de fréquence agile sur 14 bandes dont les composants ont été optimisés afin de rendre sa réalisation la moins complexe possible et qui répondent aux exigences des systèmes MultiBandes en termes de temps de commutation, de bruit de phase et de pureté spectrale. Ce nouveau type de synthétiseur de fréquences rend inévitable le déséquilibre entre les voies I et Q de l'émetteur et/ou du récepteur. La troisième partie de ce travail consiste à proposer des algorithmes originaux permettant conjointement d'égaliser le canal et de compenser numériquement le déséquilibre IQ. Ces traitements valables pour tout système OFDM permettent de relâcher les contraintes de la partie analogique.
79

Low-Power Low-Noise IQ Modulator Designs in 90nm CMOS for GSM/EDGE/WCDMA/LTE / Effekt- och Brus-Effektiva IQ Modulatorer i 90nm CMOS för GSM/EDGE/WCDMA/LTE

Johansson, Mattias, Ehrs, Jonas January 2010 (has links)
<p>The current consumption of the IQ modulator is a significant part of the totalcurrent consumption of a mobile transmitter platform and reducing it is of greatinterest. Also, as the WCDMA/LTE standards specifies full duplex transmissionsand Tx and Rx are most often using the same antenna, it is crucial to have asolution with low noise generation. Two new proposals have been studied with theaim to reduce the current consumption and noise contribution of the IQ modulator.</p><p>A current mode envelope tracking IQM is the first of the studied designs. Thisimplementation lowers the bias currents in the circuit in relation to the amplitudeof the baseband input signals, meaning that a low input amplitude results in alowering of the current consumption. It proves to be very efficient for basebandsignals with a high peak-to-average ratio. Simulations and calculations have shownthat an average current reduction of 56 % can be achieved for an arbitrary LTEbaseband signal.</p><p>The second is an entirely new passive mixer design where the baseband voltagesare sequentially copied to the RF node, removing the need for V-to-I conversion inthe mixer which reduces current consumption and noise. Results from simulationshas proven that this design is fully capable of improving both current consumptionas well as the noise levels. With an output power of 4.0 dBm, the power consumptionwas 43.3 mW, including clock generating circuits. This, combined with thefact that the design is small and simple, means that there is definitely a possibilityto replace the present IQM design with a passive mixer.</p>
80

EQ i skolan- Känslors inverkan på inlärning / EQ in school : Emotions effect on learning

Castell, Linda January 2002 (has links)
Jag har alltid intresserat mig för social kompetens och dess vikt i barn och ungdomars personliga utveckling. Min målsättning är att få grepp om hur viktigt EQ är. Syftet med detta examensarbete är att försöka tydliggöra känslornas inverkan på inlärningen. Samhällssituationen har ändrats markant sen jag själv gick i skolan och därmed även hur dagens elever mår. Många av dagens elever mår inte bra. De är ofta arga och deprimerade. Kan EQ på schemat hjälpa till att förändra och förbättra denna situation? Jag kommer att utgå ifrån dessa problemformuleringar: -Vad är EQ?-Hur påverkar känslor elevernas inlärning? -Behövs EQ i skolan? -Hur kan man arbeta med EQ i skolan? Examensarbetet innehåller en litteraturgenomgång som återger, för syftet och frågeställningarna, relevant fakta. Arbetet innehåller även en undersökningsdel, som består av en intervju med tre olika pedagoger, som alla arbetar strukturerat med EQ. Undersökningsdelens syfte är att ytterligare belysa mitt syfte med arbetet. Resultatet av examensarbetet är att EQ behöver få en mer central roll i undervisningen. Eleverna behöver arbeta med den sociala kompetensen kontinuerligt och strukturerat. Eleverna behöver en socialt fungerande miljö runt dem för att känna trygghet och harmoni. Inte förrän detta är uppnått kan de prestera i skolan.

Page generated in 0.0314 seconds