3,714 research outputs found

    The interplay between somatic and dendritic inhibition promotes the emergence and stabilization of place fields

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    During the exploration of novel environments, place fields are rapidly formed in hippocampal CA1 neurons. Place cell firing rate increases in early stages of exploration of novel environments but returns to baseline levels in familiar environments. Although similar in amplitude and width, place fields in familiar environments are more stable than in novel environments. We propose a computational model of the hippocampal CA1 network, which describes the formation, dynamics and stabilization of place fields. We show that although somatic disinhibition is sufficient to form place fields, dendritic inhibition along with synaptic plasticity is necessary for place field stabilization. Our model suggests that place cell stability can be attributed to strong excitatory synaptic weights and strong dendritic inhibition. We show that the interplay between somatic and dendritic inhibition balances the increased excitatory weights, such that place cells return to their baseline firing rate after exploration. Our model suggests that different types of interneurons are essential to unravel the mechanisms underlying place field plasticity. Finally, we predict that artificially induced dendritic events can shift place fields even after place field stabilization

    Computer assisted audit tools and techniques in real world: CAATT's applications and approaches in context

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    Nowadays, Computer Aided Audit Tools (and Techniques’) support almost all audit processes concerning data extraction and analysis. These tools were firstly aimed to support financial auditing processes. However, their scope is beyond this, therefore, we present case studies and good practices in an academic context. Although in large auditing companies Audit Tools to do data extraction and analysis are very common and applied in several contexts, we realized that is not easy to find practical examples to teach this subject. Computer Science students’ and teachers usually use application manuals’, which are adequate to explore the tools itself, but they are not enough to do real data analysis: a “hands-on” approach is essential. Despite that, our students didn’t belong to any Computer Science graduation. CAATTs are good examples of software aimed to help auditors to analyze data, to explore and study distinct data sets in auditing processes. CAATTs represent an innovative approach to do data analysis, mainly because they allow the manipulation of very large data records with no significant added costs. Frequently, users have another difficulty: they are not able to adequate their data sets or to prepare their data in order to create useful input data, to do their analysis. In this paper, we present a proposal of extraction and data analysis, based on data sets obtained from a LMS platform (Learning Management System), a real data set that can be used to support students learning about CAATTs topic. Fundamental procedures to reach specific answers using a CAATT as a main tool to do data extraction and analysis are also referred. The context for this case study was an Information Technologies applied to Auditing course in a Master Degree graduation

    The human impact on the Espinho-Paramos coast in the 20th Century

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    The relationship between man and coast has been for centuries marked by a “peaceful coexistence”, something which has been neglected over the last generations. The evolution of the coastline does not depend solely upon natural factors but also upon the type of intervention and land use of man. The “advances” of the sea along the Portuguese coastal strip are not recent; however the maintenance of the position of the coastline using engineering structures to protect the coast from the intervention of the last generations has contributed significantly to an increase of erosion and related problems. This paper describes an analysis demonstrating the influence of engineering structures on the evolution of the coastline by comparing and integrating information from cartographic documents and newspaper reports, which constitute the best source of information for the area under study. The analysis was conducted using cartography at different scales and from different sources over about a century, which allow us to estimate the advances and retreats of the coastline and determine changes in terms of the behaviour of the coastal strip in stabilised stretches. Coastal erosion has been affecting the study area since the end of the 19th century and its increasing impact has been felt throughout the 20th century. The several experiences and projects of coastal protection adopted during the 20th century have not prevented the retreat of the coastline and they have in fact become ineffective, contributing to the amplification and propagation of the phenomenon, especially from the 1970s onwards, to the south sector of the study area, where erosion rates in the period 1998/2003 ranged between 1,5m/year and 5m/year. The average coastline retreat is 2 m/year, which demanded the need to maintain and reinforce protective structures, which means an expense of millions of euros during a period of a century constituting an economic and environmental loss.La relación hombre/costa ha tenido a lo largo de los siglos una “coexistencia pacífica” que las generaciones de hoy han ido abandonando. La evolución del litoral no depende solamente de cuestiones de orden natural, sino también del tipo de intervención y del uso del territorio por parte del hombre. El “avance” del mar no es una novedad a lo largo de la franja costera de Portugal continental; sin embargo, la ansiedad por fijar el litoral mediante intervenciones de protección costera por parte de las recientes generaciones, ha contribuido de manera significativa a acelerar los problemas erosivos. En este contexto, este trabajo se propone desarrollar un análisis que demuestre la evolución del litoral, influenciado en especial por las construcciones de protección costera, comparando e integrando un conjunto de información cartográfica y de noticias en los medios de comunicación que constituyen la mejor fuente de conocimiento del área. El análisis está desarrollado en base a una cartografia de escalas y de fuentes distintas y para un período de alrededor de un siglo, lo que ha permitido calcular el retroceso y los avances del litoral y verificar las alteraciones del comportamiento de la franja costera en los sectores estabilizados. La erosión costera en el área del estudio era ya una realidad a finales del siglo XIX que ha ido aumentando a lo largo del siglo XX. Las experiencias diversas y los proyectos de defensa costera adoptados durante el siglo XX no habían conseguido frenar exactamente la erosion costera, y llegaron a ser ineficaces, contribuyendo a la amplificación y a la propagación del fenómeno, en especial a partir de la década de 1970, para el sector sur del área del estudio, donde las tasas de erosión entre 1998/2003 comprenden valores entre 1,5-5 m/año. La tasa de retroceso medio del litoral es de 2 m/año lo que ha exigido la necesidad de consolidar las estructuras de defensa, habiendo invertido muchos millones de euros en los últimos 100 años, lo que constituye una pérdida económica y ambiental

    Pseudoexfoliation: the diagnosis at first sight

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    Deaths by Choking with Food in Children: Legal Medical Aspects by Suffocation

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    The asphyxia by suffocation (choking) with foreign bodies are dramatic. Among these, the choking with food are responsible for most of these deaths. Children under four years old are particularly vulnerable due to not having a well-developed posterior dentition. The paper presents the report of two cases of suffocation with food and discusses some legal medical concepts, warning of the further prevention of such cases
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