DC electrical surveying involves the injection of current into the earth, and the measurement of the electrical potential differences this produces. A number of electrode configurations such as the Schlumberger and Wenner arrays, dipole-dipole and pole-pole geometries are in common use for electrical surveying. New acquisition systems enable the convenient collection of data with a number of common configurations at the same time. It is found however that while the recovery of layered structure from electrical surveys can be effective, the sensitivity and resolving power of such systems in detecting the presence of anomalous three-dimensional (3-D) bodies is poor. This is mainly due to the dominance of conduction pathways through the layered earth compared to the influence of small 3-D conductivity anomalies.Theoretical relationships between the responses of various survey geometries to the layered earth may be established as is shown in this thesis, but their response to 3-D targets differs strongly. This thesis introduces a new procedure for anomalous target detection by the computation of an apparent resistivity residual using multi-electrode configuration survey data. This procedure, applicable to a variety of electrode geometries, reduces the dominance of the layered earth response and enhances the signal from 3-D structures.In the development and testing of this new apparent resistivity residual, numerically modelled data were used. In order to obtain suitable test data of high accuracy it was necessary to make improvements to modelling software. For this purpose, recently developed techniques in numerical modelling such as the biconjugate gradient method, new digital linear filters for computation of Hankel transforms, and spectral formalism were employed in an integral equation approach for the software developed in this thesis.The computed apparent ++ / resistivity residual was found to depend on the array type and dimensions, the nature of the anomalous zone, geological layer geometries, and resistivity contrasts of the layers involved. While the apparent resistivity residual signature requires some measure of interpretation, it is shown to enhance the resolution and detectability of 3-D targets in a layered environment.The presence of random noise produces some degradation in the performance of the residual technique, but a normalisation procedure has been developed to alleviate the problem. A preliminary field trial showed that survey profiles of apparent resistivity residual were able to locate a subsurface conductive anomaly in an area in Western Australia.A transitional zone is defined as a layer in the earth where resistivity varies as a continuous function of depth. A theoretical formulation for the electrical response of an earth structure composed of anomalous 3-D bodies in the presence of transitional layers is introduced. Tests on synthetic survey data showed that the apparent resistivity residual is an effective anomaly detector in transitional layer environments.A multi-system method of computing an apparent resistivity residual has been developed theoretically and tested on both synthetic and field data. This new approach when applied to resistivity profiling is more sensitive to, and gives greater resolution of, localised anomalies than is possible using conventional profiling procedures.

Background The recently postulated “disease spreading hypothesis” has gained much attention, especially for Parkinson’s disease (PD). The various non-motor symptoms (NMS) in neurodegenerative diseases would be much better explained by this hypothesis than by the degeneration of disease-specific cell populations. Motor neuron disease (MND) is primarily known as a group of diseases with a selective loss of motor function. However, recent evidence suggests disease spreading into non-motor brain regions also in MND. The aim of this study was to comprehensively detect NMS in patients suffering from MND. Methods We used a self-rating questionnaire including 30 different items of gastrointestinal, autonomic, neuropsychiatric, and sleep complaints [NMS questionnaire (NMSQuest)], which is an established tool in PD patients. 90 MND patients were included and compared to 96 controls. Results In total, MND patients reported significantly higher NMS scores (median: 7 points) in comparison to controls (median: 4 points). Dribbling, impaired taste/smelling, impaired swallowing, weight loss, loss of interest, sad/blues, falling, and insomnia were significantly more prevalent in MND patients compared to controls. Interestingly, excessive sweating was more reported in the MND group. Correlation analysis revealed an increase of total NMS score with disease progression. Conclusion NMS in MND patients seemed to increase with disease progression, which would fit with the recently postulated “disease spreading hypothesis.” The total NMS score in the MND group significantly exceeded the score for the control group, but only 8 of the 30 single complaints of the NMSQuest were significantly more often reported by MND patients. Dribbling, impaired swallowing, weight loss, and falling could primarily be connected to motor neuron degeneration and declared as motor symptoms in MND.

Background The recently postulated “disease spreading hypothesis” has gained much attention, especially for Parkinson’s disease (PD). The various non-motor symptoms (NMS) in neurodegenerative diseases would be much better explained by this hypothesis than by the degeneration of disease-specific cell populations. Motor neuron disease (MND) is primarily known as a group of diseases with a selective loss of motor function. However, recent evidence suggests disease spreading into non-motor brain regions also in MND. The aim of this study was to comprehensively detect NMS in patients suffering from MND. Methods We used a self-rating questionnaire including 30 different items of gastrointestinal, autonomic, neuropsychiatric, and sleep complaints [NMS questionnaire (NMSQuest)], which is an established tool in PD patients. 90 MND patients were included and compared to 96 controls. Results In total, MND patients reported significantly higher NMS scores (median: 7 points) in comparison to controls (median: 4 points). Dribbling, impaired taste/smelling, impaired swallowing, weight loss, loss of interest, sad/blues, falling, and insomnia were significantly more prevalent in MND patients compared to controls. Interestingly, excessive sweating was more reported in the MND group. Correlation analysis revealed an increase of total NMS score with disease progression. Conclusion NMS in MND patients seemed to increase with disease progression, which would fit with the recently postulated “disease spreading hypothesis.” The total NMS score in the MND group significantly exceeded the score for the control group, but only 8 of the 30 single complaints of the NMSQuest were significantly more often reported by MND patients. Dribbling, impaired swallowing, weight loss, and falling could primarily be connected to motor neuron degeneration and declared as motor symptoms in MND.

INTRODUCTION: With the emergence of the COVID 19 pandemic, a new disease, Multisystem Inflammatory Syndrome in Children (MIS-C), had evolved. Increasing number of children are being reported to have MIS-C in the U.S. & worldwide. In the U.S. there are currently 2617 MISC cases reported. MIS-C & Kawasaki Disease (KD), have almost the same presentation, making clinical differentiation difficult. This study aims at differentiating KD & MIS-C which could assist clinicians to determine which one they could be dealing with in their practices. METHODS: Clinical features & laboratory values were collected from published studies found by queries on PubMed & other websites. Reported values were selected from published systemic reviews, meta-analyses, & large retrospective chart studies. RESULTS: In KD, the most prevalent clinical features are fever (100%) & the 5 KD-defining clinical features: oral mucosal changes (96.5%), rash (96%), non-purulent conjunctivitis (89%), extremity changes (75.6%), and cervical lymphadenopathy (62.7%). MIS-C also presents with fever (100%) but has lower prevalence of oral mucosal changes (23%), rash (38.2%), non-purulent conjunctivitis (44.0%), extremity changes (2.5%), & cervical lymphadenopathy (4%). MIS-C leads to higher rates of ventricular dysfunction (39.3%), myocarditis (23%), & shock. For cardiac biomarkers, MIS-C has elevated troponin I (x6 normal) & Beta Natriuretic Peptide (BNP) (x414 normal), while KD has elevations of troponin I (x1.9 normal) & BNP (x15 normal). MIS-C has higher elevations in ESR, CRP, and D-Dimer at x6, x30, and x40 from the normal values, respectively, while KD has elevations of x2.8, x2.1, x7.3 from the normal values, respectively. MIS-C is associated with neutrophilia, thrombocytopenia, & anemia in 22% of cases. KD is associated with mild neutrophilia & anemia. KD has thrombocytosis in the subacute phase (x1.46 normal). CONCLUSION: Our results demonstrated that there are overlaps & differences in clinical and laboratory features. Fever is present in both KD & MIS-C, however the 5 KD defining clinical features of KD are less frequent in MIS-C. MIS-C induces higher levels of troponin I & BNP, findings that could potentially explain for higher rates of ventricular dysfunction & myocarditis. MIS-C causes higher elevations in inflammatory markers & D-Dimers compared to KD. Uniquely, thrombocytopenia is commonly present in MISC rather than in KD. Differentiating KD & MIS-C can be challenging, but by focusing closely on the clinical & laboratory features, clinicians may be able to distinguish between the two &, therefore, deliver the most appropriate care to patients in their practices.

Introduction: Coronavirus 2019 (SARS-CoV-2) infection in children occurred in Peru as of March 2020, leading to pediatric patients' hospitalization in areas adapted for this purpose at the Edgardo Rebagliati Martins National Hospital. In the beginning, the demand for hospitalization was low, but it increased gradually. Consistent with international reports, the majority of patients presented mild or moderate symptoms. Nonetheless, there were also severe cases, even fatal ones. Objectives: To describe the characteristics and clinical outcome of pediatric patients with COVID-19 hospitalized in a referral hospital in Lima, Peru, between March and August 2020. Methods: A descriptive and inferential cross-sectional study was carried out. The population includes all hospitalized patients in the Department of Pediatrics, with clinical and surgical diagnoses associated with COVID-19. Results: We included 100 patients, with an average age of 83.4 ± 54 months, with a predominance of male patients (55%). Hospitalized patients were grouped into five categories: respiratory failure (17%), multisystemic inflammatory syndrome (MIS-C) (31%), neurological presentation (19%), acute abdomen (20%), and patients with oncological problems (13%). Most of the patients (74%) had comorbidities. Regarding the presenting symptoms, intestinal pain predominated in the appendicitis group (90%, p < 0.001), fever was present in most patients with respiratory failure (64.7%); multisystemic inflammatory syndrome (90.3%), neurological manifestations (15.8%), acute abdomen (50%) and oncological conditions (61.5%) were also present in these patients. Kawasaki symptoms were found in 38.7% of the patients with multisystemic inflammatory syndrome. Mortality was 4%. Respiratory problems (29.4%) and multisystemic inflammatory syndrome (22.6%) required admission to intensive care, more frequently than the other presentations (p = 0.008). Conclusions: We conclude that the vulnerability in the pediatric population is the one that has preexisting conditions. We divided our patients according to presentation, diagnosis, and complications, which were predominantly respiratory. We also had oncological patients with COVID-19. / Introducción: La infección por coronavirus 2019 (SARS-CoV-2) en niños se presentó en Perú desde marzo del 2020. Desde entonces fue necesario internar pacientes pediátricos en el Hospital Nacional Edgardo Rebagliati Martins, en el área de hospitalización adaptada para dicho propósito. Al inicio, la demanda de hospitalización era baja y se fue incrementando progresivamente. Coincidiendo con los reportes internacionales, la mayoría presentó cuadros leves o moderados, pero también hubo casos graves e incluso mortales. Objetivos: Describir las características y el desenlace clínico de los pacientes pediátricos con COVID-19 hospitalizados en un hospital de referencia en Lima, Perú, entre marzo y agosto de 2020. Métodos: Se realizó un estudio transversal descriptivo e inferencial. La población incluyó a todos los pacientes que se hospitalizaron en el Departamento de Pediatría Clínica, con diagnósticos clínicos y quirúrgicos asociados a COVID-19. Resultados: Incluimos 100 pacientes, con edad promedio de 83,4 ± 54 meses, con predominio de varones (55%). Los pacientes hospitalizados fueron agrupados en cinco categorías: insuficiencia respiratoria (17%), síndrome inflamatorio multisistémico (31%), presentación neurológica (19%), abdomen agudo (20%) y pacientes con problemas oncológicos (13%). La mayoría de los pacientes (74%) tenían comorbilidades. Respecto a los síntomas de presentación, el dolor intestinal predominó en el grupo de apendicitis (90%, p < 0,001), la fiebre estuvo presente en la mayoría de los pacientes con falla respiratoria (64,7%), el síndrome inflamatorio multisistémico se registró en 90,3%, la sintomatología neurológica en 15,8%, el abdomen agudo 50% y oncológicos en 61,5% de los pacientes. Los síntomas de Kawasaki estuvieron presentes en 38,7% de los pacientes con síndrome inflamatorio multisistémico. La mortalidad fue de 4%. En 29,4% de problemas respiratorios y en 22,6% de síndrome inflamatorio multisistémico, se requirió de admisión en cuidados intensivos, lo que fue más frecuente que las otras presentaciones (p = 0,008). Conclusiones: Se concluye que la población pediátrica vulnerable es aquella con comorbilidades preexistentes. La división de pacientes en nuestro estudio fue definida por la presentación, diagnóstico y complicaciones predominantemente con problemas respiratorios, y en pacientes oncológicos con COVID-19. / Revisión por pares

L’objectif général de cette thèse est d’étudier la production quantitative (i.e., nombre de mots) et qualitative (i.e. regroupements et alternances) du verbe d’action dans le vieillissement normal et dans les pathologies du mouvement à travers la tâche de fluence d’action, comparativement aux fluences classiques (i.e., sémantique et littérale). Nous avons montré que la production lors d’une tâche de fluence d’action est altérée chez des adultes âgés (60 ans et plus) comparativement à des adultes jeunes (30 ans et moins) et qu’elle est en lien avec les fonctions exécutives (Expérience 1) et la mémoire de travail (Expérience 3) chez l’adulte âgé. L’effet de l’âge paraît être modifié par le temps de production, les adultes âgés produisant moins de verbes d’action que les adultes jeunes pour un temps de trois minutes (Expérience 1) mais pas pour des temps d’une (Expérience 2) et de deux minutes (Expérience 3). De plus, les adultes âgés prenaient davantage en considération la consigne temporelle lors des tâches de fluence verbale que les adultes jeunes (Expérience 2). Les données d’une tâche d’association verbale (Expérience 4) indiquaient que les associations entre les noms et les verbes sont modifiées par l’âge. Nous avons comparés les performances de patients atteints de pathologiesdu mouvement à celles de participants contrôles lors de la tâche de fluence d’action. Nous avons montré que la production quantitative lors cette tâche est altérée chez des patients atteints de maladie de Parkinson (Expérience 5) et d’atrophie multisystématisée (Expérience 6). Dans le tremblement essentiel (Expérience 7), nous avons montré une atteinte de la fluence d’action alors que le traitement des verbes, lors d’une tâche de décision lexicale, n’était pas altéré. De plus, la chirurgie (stimulation cérébrale profonde) modifiait qualitativement la production dans la tâche de fluence d’action. Nos données montrent un impact du vieillissement normal et des pathologies du mouvement sur la production du verbe d’action, enraison de la nature fortement exécutive de ce processus. / The aim of this thesis is to investigate the production of action verbs through the action fluency task, in comparison to classical fluency tasks (i.e., semantic and letter). In first instance, production has been studied, both quantitatively and qualitatively, in aging. We have shown that action fluency is impacted by healthy aging and is related to executive functions (Experiment 1) and working memory (Experiment 3) in older adults. This effect of age appearsto be affected by production time, with older adults producing fewer action verbs than younger adults in three minutes (Experiment 1) but not in one (Experiment 2) and two minutes (Experiment 3). In addition, older adults took more into account the time instruction during verbal fluency tasks (Experiment 2). The verbal association task’s data (Experiment 4) indicated that associations between nouns and verbs are modified by age. In second instance,the production of action verbs has been studied within movement disorders. We have shown that the production in the action fluency task and the adaptation to time instruction are impacted by Parkinson's disease (Experiment 5). We have also shown that action fluency is altered within an atypical parkinsonism, multiple system atrophy (Experiment 6). In essential tremor (Experiment 7), we have shown an impairment of action fluency while verbs treatment, in a lexical decision task, was not altered. In addition, surgery (deep brain stimulation) qualitatively modified the production of verbs in action fluency. Our data highlight the impact of healthy aging and movement disorders on the production of action verb, due to the highly executive nature of this process.

In a time where some 2.4 billion Internet users exist worldwide, children are increasingly impacted by the Internet's influence, both directly and indirectly. With technology now playing a significant role in childhood learning and social development, many unforeseen shifts are occurring that will ultimately impact lifespan development. Although researchers have provided mixed results concerning the impact of the Internet on learning and social development, the body of evidence indicates that veteran K-8 educators who are comfortable and experienced with the Internet view it more favorably. This grounded theory study systematically generated the multisystem technological engagement theory (MSTET) to explain the impact of the Internet on childhood learning and social development. Semistructured interviews were conducted with 14 self-identified veteran K-8 educators. Analysis of the data was conducted using a 3-tiered method of coding that was verified through the process of triangulation and member-checking. Results of this study indicate that the veteran K-8 educators perceived the Internet's impact as positive, given a specific set of conditions: experience and comfort with the Internet, collaboration with parents, a healthy balance between face-to-face and online social interactions, boundaries, and maximization of benefits from available information and resources. These findings may enhance social change initiatives by providing an evidence basis for both targeted instruction and school counseling practice that facilitates healthy K-8 learning and social development in the Internet Age.

Les systèmes côtiers pélagiques sont caractérisés par de multiples apports de matière organique particulaire (MOP) d’origine autochtone (phytoplancton) ou allochtone (continentale, benthique) dont la variabilité spatiale et temporelle peut être forte. L’objectif de ma thèse était 1) de quantifier la composition de la MOP des systèmes côtiers pélagiques, 2) de déterminer les forçages à sa dynamique spatio-temporelle et 3) d’investiguer le lien entre bactéries et composition de la MOP. Cette étude a été menée sur douze systèmes (estuaire, lagune, rias, baies, littoraux) distribués sur les trois façades maritimes françaises, en combinant rapports isotopiques et élémentaires (composition), acides gras (lien MOP-bactéries) et statistiques multivariées (forçages).A l’échelle multi-systémique et/ou intra-systémique, deux grands gradients sont observés :- un gradient côte (plus forte contribution continentale et benthique) – large (MOP phytoplanctonique), principalement lié à l’hydrodynamique sédimentaire (débits des fleuves, remise en suspension du matériel benthique) et à la proximité des sources allochtones- un gradient Sud (présence de MOP issue de la diazotrophie) – Nord (absence de cette MOP), en lien avec le statut trophique (oligo vs méso/eutrophie) des systèmes.La saisonnalité de la dynamique temporelle de la composition de la MOP est fortement variable selon les sites. Elle est généralement plus forte près de la côte et plus faible au large et en zone amont de l’estuaire étudié. Cette dynamique est également reliée à l’hydrodynamique sédimentaire.Enfin, l’étude a révélé que la biomasse bactérienne est principalement associée à la MOP continentale et benthique. / Pelagic coastal systems are characterized by multiple inputs of particulate organic matter (POM) from autochthonous (phytoplankton) and allochthonous (continental, benthic) origin whose spatial and temporal variability can be high. The aims of my PhD were to 1) quantify POM composition in pelagic coastal systems, 2) determine the forcings to its spatio-temporal dynamics and 3) investigate the link between bacteria and POM composition. This study was conducted on twelve systems (estuary, lagoon, bays, rias, littoral) distributed over the three maritime facades of France by combining the use of elemental and isotopic ratios (composition), fatty acids (POM-bacteria link) and multivariate analysis (forcings).At multi-systems and/or intra-system scale, two main gradients are observed:- an inshore (higher continental and benthic contribution) - offshore gradient (phytoplanktonic POM) mainly related to hydrodynamics and sedimentary hydrodynamics (river flow, resuspension of benthic material) and to the proximity to allochthonous sources- a South (POM related to diazotrophy) – North (absence of this POM) gradient, associated to the trophic status (oligo vs meso/eutrophy) of the studied systems.The seasonality of spatio-temporal dynamics of POM composition is highly variable depending on the station. It is in general higher near the coast and lower offshore and upstream in the studied estuary. This dynamic is also strongly associated to sedimentary hydrodynamics.Finally, this study highlight that bacterial biomass is mainly associated to continental and benthic POM.