Criticality and its effect on other cortical phenomena

Neuronal avalanches are a cortical phenomenon defined by bursts of neuronal firing encapsulated by periods of quiescence. It has been found both in vivo and in vitro that neuronal avalanches follow a power law distribution which is indicative of the system being within or near a critical state. A system is critical if it is poised between order and disorder with the possibility of minor event leading to a large chain reaction. This is also observed by the system exhibiting a diverging correlation length between its components as it approaches the critical point. It has been shown that neuronal criticality is a scale-free phenomenon observed throughout the entire system as well as within each module of the system. At a small scale, neuronal networks produce avalanches which conform to power law-like distributions. At a larger scale, we observe that these systems consist of modules exhibiting long-range temporal correlations identifiable via Detrended Fluctuation Analysis (DFA). This phenomenon is hypothesised to affect network behaviour with regards to information processing, information storage, computational power, and stability - The Criticality Hypothesis. This thesis attempts to better understand critical neuronal networks and how criticality may link with other neuronal phenomena. This work begins by investigating the interplay of network connectivity, synaptic plasticity, and criticality. Using different network construction algorithms, the thesis demonstrates that Hebbian learning and Spike Timing Dependent Plasticity (STDP) robustly drive small networks towards a critical state. Moreover the thesis shows that, while the initial distribution of synaptic weights plays a significant role in attaining criticality, the network's topology at the modular level has little or no impact. Using an expanded eight-module oscillatory spiking neural network the thesis then shows the link between the different critical markers we use when attempting to observe critical behaviour at different scales. The findings demonstrate that modules exhibiting power law-like behaviour also demonstrate long-range temporal correlations throughout the system. Furthermore, we show that when modules no longer exhibit power law-like behaviour we find that they become uncorrelated or noisy. This shows a correlation between power law-like behaviour observed within each module and the long-range temporal correlations between the modules. The thesis concludes by demonstrating how criticality may be linked with other related phenomena, namely metastability and dynamical complexity. Metastability is a global property of neuronal populations that migrate between attractor-like states. Metastability can be quantified by the variance of synchrony, a measure that has been hypothesised to capture the varying influence neuronal populations have over one another and the system as a whole. The thesis shows a correlation between critical behaviour and metastability where the latter is most reliably maximised only when the former is near the critical state. This conclusion is expected as metastability, similarly to criticality reflects the interplay between the integrating and segregating tendencies of the system components. Agreeing with previous findings this suggests that metastable dynamics may be another marker of critical behaviour. A neural system is said to exhibit dynamical complexity if a balance of integrated and segregated activity occurs within the system. A common attribute of critical systems is a balance between excitation and inhibition. The final part of the thesis attempts to understand how criticality may be linked with dynamical complexity. This work shows a possible connection between these phenomena providing a foundation for further analysis. The thesis concludes with a discussion of the significant role criticality plays in determining the behaviour of neuronal networks.Open Acces

Decadal changes in the Canary upwelling system as revealed by satellite observations: Their impact on productivity

Satellite-derived sea-surface temperature (SST) data were used to study the variability of the Canary Upwelling Ecosystem-CUE (12 to 43N) over the last two decades of the 20th century. The analysis reveals well known patterns of climatology and seasonal variability in this upwelling system. In contrast to quasi-regular decadal oscillations of SST anomalies observed in the open ocean, the coastal variability during the 1980s–1990s was better described as a decadal scale shift of the upwelling regime intensity. The analysis of the upwelling index and coastal zonal gradient of SST showed that this shift occurred earlier (∼1992) in the northern part of the CUE (off western Iberia) and some years later (∼1995) off the northwest African coast. The long-term variability of upwelling-favorable wind forcing during the examined period provides reasonable explanations for the observed shift of the upwelling intensity and its timing for the whole CUE. Finally, changes in the productivity of several small pelagic fish species observed for the same period suggest that there was a response of the ecosystem to these changes

Cerebral venous thrombosis: an unexpected complication from spinal surgery

PURPOSE: To provide new insights into the pathophysiology, prevention and diagnosis of cerebral venous thrombosis (CVT) associated with iatrogenic cerebrospinal fluid (CSF) leaks and/or external CSF drainage. METHODS: Case report and literature review. RESULTS: We describe the case of a 30-year-old woman who developed a CSF fistula after lumbar spinal surgery. The treatment included rest, hydration, caffeine, and continuous lumbar CSF drainage. After closure of the fistula, the patient complained of severe orthostatic headache. Thrombosis involving the superior sagittal sinus, the right transverse sinus, the right sigmoid sinus, and the right jugular vein was diagnosed after neurological deterioration. CONCLUSION: A few reports have associated CVT with various forms of spinal meningeal injury. However, it has been rarely documented following spinal surgery complicated by accidental durotomy and/or external lumbar CSF drainage. CSF hypovolemia may precipitate CVT in patients having prothrombotic risk factors. Patients who have or had CSF leaks and/or lumbar CSF drains who present with symptoms of intracranial CSF hypotension should remain in the horizontal position to prevent CVT. In that context, the diagnosis of CVT depends on a high degree of suspicion

Climatología y reconstrucción de series temporales de descarga fluvial en el Noroeste de Iberia: influencia en el balance de densidad sobre la plataforma

River runoff off northwest Iberia generates a low-density buoyant structure with a strong influence on shelf and coastal circulation. This study estimates the runoff to the shelf of the ten largest rivers in the region based on the furthest downstream gauge records available, and also takes into account the basin area downstream from the station (22% of the basin area for the entire study region). Monthly statistics were computed to obtain mean values for each river to cover the recurrent lack of runoff data in the region. In order to reconstruct gaps in the time series on a daily scale, a method based on the observed discharge of a nearby river basin was used. In addition, the influence of runoff on the shelf was analyzed using monthly CTD data sampled during a 12-year period in the Ría de Vigo and the adjacent shelf. The CTD series shows the existence of a buoyant structure with maximum growth during winter and with large variability of its thermal anomaly. The salinity anomaly correlated significantly with mean winter monthly values of the North Atlantic Oscillation (NAO) index. This atmospheric index integrates both the influence of precipitation —and therefore runoff— and the predominant winds during winter that contribute to the accumulation of fresh water over the shelf.La descarga fluvial en el Noroeste de la Península Ibérica genera una estructura de baja densidad con altas implicaciones en la circulación costera y de plataforma. Este estudio estima la descarga fluvial en la plataforma para los 10 ríos más caudalosos en la región, utilizando para ello los registros de caudal disponibles y suplementados para tener en cuenta el área de la cuenca que se encuentra aguas abajo de las estaciones de aforo (~22% del área total de la región de estudio). Se han calculado valores medios mensuales para cada río, que resultan útiles para cubrir la recurrente carencia de datos en la región de estudio. Para reconstruir huecos en las series temporales en una escala diaria, se utiliza un simple método basado en las observaciones realizadas en una cuenca cercana. La influencia de la descarga fluvial sobre la hidrología en la plataforma es analizada mediante datos mensuales de CTD muestreados en la Ría de Vigo y la plataforma adyacente durante los últimos 12 años. Las series temporales de CTD muestran plumas de agua dulce con máximo crecimiento durante el invierno y con gran variabilidad en su estructura térmica. La correlación de la anomalía de densidad con valores medio invernales del índice de la Oscilación del Atlántico Norte (NAO) muestra valores significativos. Este patrón atmosférico es representativo de la influencia de la precipitación —y por tanto, la descarga fluvial— y los vientos predominantes durante el invierno, que contribuyen a la acumulación de agua dulce sobre la plataforma

Mudanças climáticas entre utopia e distopia: uma análise da representação do fenômeno nas imprensas brasileira e francesa

This paper focuses on the representation of climate change in French and Brazilian newspapers. It reports on the results of a discourse analysis of Le Monde, Le Figaro, O Estado de São Paulo and O Globo.The heuristic assumption driving this study is that the representation of climate change in the press is divided between utopic and dystopic ideas. The theoretical framework is based on philosophical works as well as on literary studies about utopia and dystopia. The concept of “moment discursif” and Sophie Moirand’s works related to daily French press are the bases for discourse analysis. The study finds that the representation of climate change in the newspapers is shaped by the idea of scientific and politic consensus, promoting individual initiatives, and nature preservation and technologies as the answer for climate change.O artigo apresenta os resultados de uma análise do discurso dos jornais Le Monde, Le Figaro, O Estado de São Paulo e O Globo sobre a representação das mudanças climáticas. A hipótese heurística que conduz a pesquisa é de que a representação do fenômeno nos jornais se divide entre ideias utópicas e distópicas. O quadro teórico baseia-se em trabalhos filosóficos e em estudos literários sobre utopia e distopia. A análise do discurso é fundamentada nos trabalhos sobre a imprensa diária francesa realizados por Sophie Moirand e no conceito de “momento discursivo”. Observa-se que a representação das mudanças climáticas nos jornais analisados estrutura-se sobre a ideia de consenso científico e político, promovendo iniciativas individuais, o ideal de preservação da natureza e o uso de tecnologias como resposta ao problema climático.L’article présente les résultats d’une analyse discursive des journaux Le Monde, Le Figaro, O Estado de São Paulo et O Globo au sujet  de la représentation du changement climatique. L’hypothèse heuristique fil conducteur de l’étude est que la représentation du phénomène dans les journaux analysés se partage entre idées utopiques et dystopiques. Le cadre théorique trouve ses sources dans des travaux philosophiques ainsi que dans des études littéraires sur l’utopie et la dystopie. L’analyse du discours est basée sur les travaux de Sophie Moirand sur la presse quotidienne nationale française, ainsi que sur le concept de “moment discursif”. Nous observons que la représentation du changement climatique dans les journaux analysés se structure autour de l’idée d’un consensus tant scientifique que politique, de la promotion des initiatives individuelles, ainsi que de la préservation de la nature et de l’usage des technologies comme réponse au problème climatique

Entre direito e democracia : os limites da racionalidade para um projeto de direito inclusivo em Habermas

Dissertação (mestrado)—Universidade de Brasília,Instituto de Ciências Humanas, Programa de Pós-Graduação em Metafísica, 2018.Essa pesquisa tem por objetivo expor a forma como Habermas concebe o social e o direito sob o paradigma da racionalidade comunicativa, perscrutando se, ao final, trata-se de um projeto que permite a alteridade. Para tanto aborda os seguintes temas da obra do filósofo: a) inserção de seu projeto no que ele chama de pensamento pós-metafísico e identificação da modernidade como um projeto da racionalidade; b) reconstrução da teoria sociológica da ação sob o paradigma do agir comunicativo a partir da teoria dos atos de fala e de uma renovada concepção do mundo da vida pela inserção de ambos no contexto da pragmática universal; c) relação entre moral e direito do que decorre também a relação entre soberania e direitos humanos, autonomia pública e privada, Estado e direito. Ao final traz notas críticas sobre o pensamento de Habermas sob o paradigma da alteridade, apontando o pensamento de Derrida como um possível candidato a complementar sua teoria.The aim of this study is to describe the manner that Habermas conceive the social and the law under the communicative rationality paradigm, analysing if this project admits the alterity. The research approaches a) the insertion of Habermas’ project in the post-metaphysical thinking and the identification of modernity as a project of rationality; b) the reconstruction of social action theory under the paradigm of communicative action, based on the speech acts theory and on a renewed conception of the life world through the insertion of both in the context of universal pragmatic; c) the relation between moral and law, related with sovereignty and human rights, public and private autonomy, State and law. The conclusion criticises Habermas’ thinking under the alterity paradigm, indicating Derrida’s thinking to complete communicative rationality theory

Quase-mercado e isomorfismo

O presente estudo aborda a forma como as escolas secundárias públicas com ensino profissional (cursos profissionais) de qualificação profissional de nível 4, se têm vindo a adaptar às novas configurações do sistema educativo, na integração desta oferta educativa. Esta via de ensino tem contribuído de forma expressiva para o aumento da escolarização do ensino secundário nos últimos anos em Portugal. Tendo presentes estas novas configurações institucionais que resultaram em mudanças no sistema educativo, o Estado parece agora legitimar e apelar ao comportamento competitivo, numa ação conduzida por lógicas de mercado (quase-mercado). Destacamos aspetos fundamentais como os reflexos da crise económica e financeira no desemprego e na formulação de quadros de incerteza, o reforço do regime de autonomia, a imposição de condições de administração e gestão participativa, a estrutura e organização desta via de ensino, e o planeamento da oferta formativa como contextos centrais para a reflexão e identificação da ação estratégica. Recorremos ao conceito de instituição, o qual define o ambiente organizacional como um espaço de trocas de recursos económicos e simbólicos, e enfatiza que as estruturas organizacionais são o resultado de pressões exercidas pelo ambiente institucional em que estão inseridas, e não entidades passivas, pois desenvolvem práticas e estratégias consideradas apropriadas para assegurar o seu poder, legitimidade e sobrevivência. Através da análise da evolução das ofertas de cursos às escalas nacional e regional e de entrevistas com escolas públicas e municípios da rede EXCEL, bem como de escolas privadas dos mesmos concelhos, concluímos que numa primeira fase as escolas públicas pautaram as suas ofertas por estratégias defensivas, face à dependência de recursos, à procura de estabilidade organizativa e de afetação do corpo docente instalado e à perceção duvidosa sobre a autonomia. A segunda fase, a partir de 2011, carateriza-se pelo reforço da centralidade do Estado que passou a determinar as ofertas agindo como representante único da procura pública, ao mesmo tempo que se manteve a pressão concorrencial sobre as escolas como atores da oferta, estruturando um quase-mercado aproximado a um monopsónio

A high-resolution hydrodynamic-biogeochemical coupled model of the Gulf of Cadiz – Alboran Sea region.

The southern Iberia regional seas comprise the Gulf of Cadiz and the Alboran Sea sub-basins connected by the narrow Strait of Gibraltar. Both basins are very different in their hydrological and biological characteristics but are, also, tightly connected to each other. Integrative studies of the whole regional oceanic system are scarce and difficult to perform due to the relative large area to cover and the different relevant time-scales of the main forcings in each sub-basin. Here we propose, for the first time, a fully coupled, 3D, hydrodynamic-biogeochemical model that covers, in a single domain (~2km resolution) both marine basins for a 20 years simulation (1989-2008). Model performance is assessed against available data in terms of spatial and temporal distributions of biological variables. In general, the proposed model is able to represent the climatological distributions of primary and secondary producers and also the main seasonality of primary production in the different sub-regions of the analyzed basins. Potential causes of the observed mismatches between model and data are identified and some solutions are proposed for future model development. We conclude that most of these mismatches could be attributed to the missing tidal forcing in the actual model configuration. This model is a first step to obtain a meaningful tool to study past and future oceanographic conditions in this important marine region constituting the unique connection of the Mediterranean Sea with the open world’s ocean

Presença de recessões gengivais ou lesões cervicais não cariosas em dentes sujeitos a trauma oclusal : revisão sistemática

Introdução: O papel do trauma oclusal na etiologia das recessões gengivais (GR) e das lesões cervicais não cariosas (LCNC) é um tema relevante na Medicina Dentária moderna, dada a elevada prevalência e implicações estéticas e funcionais que acarretam. Contudo, o seu papel como fator causal ou contribuinte permanece ainda alvo de debate e controvérsia, em particular no que respeita às recessões gengivais. Com vista a esclarecer esta temática, delineou-se como objetivo principal do estudo, realizar uma revisão sistemática para se verificar a possível influência dos fatores oclusais na ocorrência de LCNC e RG. Metodologia: Para se responder à questão de investigação formulada (“Existe uma relação entre a presença de trauma oclusal e o aparecimento de recessões gengivais ou lesões cervicais não cariosas?”) efetuou-se uma pesquisa bibliográfica de artigos respeitantes ao tema, publicados desde março de 2010 a março de 2020, com termos de pesquisa e critérios de inclusão e exclusão bem definidos. Os artigos obtidos foram primeiramente sujeitos a uma análise do título e/ou abstract e, finalmente, a leitura integral. Dada a quantidade e diversidade dos estudos, foi efetuada uma análise qualitativa dos mesmos. Resultados: Com base nos critérios estabelecidos foram obtidos 757 artigos iniciais. Após revisão, 19 artigos foram sujeitos a análise de texto completo, restando 5 artigos para inclusão (1 case-control e 4 cross-sectional). Os resultados descritos nos artigos revelam-se distintos, dada a heterogeneidade de artigos sujeitos a análise. Conclusão: Considerando as limitações desta revisão sistemática foi possível concluir: poucos estudos relativos a este tema foram publicados nos últimos 10 anos, em particular, respeitante à associação entre RG e fatores oclusais; LCNC e RG apresentam etiologia multifatorial; trauma oclusal parece estar associado com a ocorrência das LCNC; não foi possível tirar conclusões a respeito da associação entre trauma oclusal e RG.Introduction: Occlusal trauma in the etiology of gingival recession (GR) and noncarious cervical lesion (NCCL) remains of great relevance in modern dentistry, given the increased prevalence and its esthetic and functional implications. However, its role as a causal or contributing factor remains a matter of debate and controversy, particularly concerning GR. To clarify this theme, the main objective of this research was to carry out a systematic review (SR) to verify the possible influence of occlusal factors on the occurrence of GR and NCCL. Methods: In order to answer the research question ("Is there a relationship between the presence of occlusal trauma and the appearance of gingival recessions or non-carious cervical lesions?"), a bibliographic search was conducted focusing on articles published since March 2010 to March 2020, with well-defined search terms for inclusion and exclusion criteria. Firstly, it was analyzed the title and/or abstract of the articles obtained and, finally, full-text reading was carried out. Given the amount and diversity of final studies, a qualitative analysis was carried out. Results: Based on the established criteria, it was possible to obtain an initial 757 articles. After screening, 19 articles were excluded after full-text read, remaining 5 articles for inclusion (1 case-control, and 4 cross-sectional studies). The results described in the articles were different, given the heterogeneity of articles subject to analysis. Conclusion: Within the limitation of this SR, it was possible to conclude that: few studies regarding the topic have been published in the past 10 years, in particular, about the association of GR with occlusal factors; NCCL and GR present a multifactorial etiology; traumatic occlusion seem to be associated with the occurrence of NCCL; it is not possible to draw any conclusions regarding the association between occlusal trauma and GR