Search

Spinal Cord Injuries (SCI) have severe consequences such as tetraplegia and paraplegia, which dramatically affect the healthcare of the patients. Successful therapies for such injuries are yet to be attainable. Currently, there is a focus on the study and implementation of small implantable devices that are capable of providing in-vivo electrical stimulation to the spinal cord. Since the impedance of the neural tissue experiences constant changes, the focus is on using current stimulation instead of voltage, to compensate the impedance variations. Furthermore, the usage of scaffolds to provide alignment on the regrown fibers, combined with electrical stimulation is viewed as possible solution for SCI therapy. The NeuroStim- Spinal project, in which this work is inserted, aims to propose a SCI therapy based on in-vivo electrical stimulation combined with 3D printed scaffolds that have in its composition based materials (GBM) and adipose derived decellularized tissue (adECM). The work presented is an application-specific integrated circuit design (ASIC) that provides current-mode stimulation for neuronal regeneration, with the objective of providing in-vivo electrical stimulation for SCI therapy. The main challenges on the design of such devices is in obtaining low circuit area and power consumption, while maintaining the specifications needed. These characteristics are important, since it is intended to be an implantable device. The stimulation circuit consists of, a communication interface with a microcontroller using the Serial Peripheral Communication (SPI) protocol, a 10-bit DAC (Digital-to-Analog Converter) based on a binary charge scaling architecture, a voltage-to-current converter with a feed-forward voltage attenuator (FFVA) architecture, and a H-bridge circuit composed of CMOS switches to drive the scaffold. Results demonstrate that the system developed is capable of driving current from 0 to 200μA with an absolute error bellow 0.75μA. In addition, the developed circuit can provide these range of currents with high linearity to a 15k load impedance. The system can still provide linear stimulation for higher load impedance’s, but in smaller current ranges. Furthermore, the circuit uses a supply voltage of 5V and has an average power dissipation of 19.5mW. The ASIC was developed using a 0.35μm CMOS technology, has dimensions of 270μm per 700μm, which corresponds to a total area of 0.19mm2. The work was developed using the Cadence software. Lesões na Medula Espinhal são causadas sobretudo devido acidentes rodoviários, quedas e lesões na prática de desportos. Estas têm graves consequências no estado de saúde dos pacientes, uma vez que saõ responsáveis por diagnósticos como tetraplegia e paraplegia. Até hoje, terapias eficazes para este tipo de lesões ainda não foram conseguidas, o que torna esta temática num foco de estudo. Atualmente, uma das orientações deste foco de estudo está direcionado em dispositivos elétricos implantáveis capazes de estimular a espinal medula in-vivo, promovendo a regeneração da mesma. Adicionalmente, o uso de materiais (scaffolds) que permitem manter o alinhemento no crescimento das fibras, em conjunto com estimulação elétrica é vista como a solução consensual para terapias relacionadas com Lesões na Medula Espinhal. Assim, o projeto NeuroStimSpinal, na qual este trabalho se insere, foi proposto. Este tem como objetivo propor uma terapia para esta problemática usando estimulação elétrica em conjunto com scaffolds impressas em 3D. O trabalho apresentado nesta dissertação é baseado num circuito integrado de aplicação específica (CIAE) para estimulação em corrente da espinal medula, com o intuito de promover a regeneração da mesma. Os desafios na implementação deste tipo de circuitos estão relacionados com a necessidade destes terem de ser pequenos em tamanho e consumir uma potência reduzida, mantendo as características necessárias para a estimulação, uma vez que é necessário que o mesmo faça parte de um dispositivo implantável. O circuito de estimulação proposto consiste: numa interface de comunicação com a unidade de controlo (microcontrolador) usando o protocolo Serial Peripheral Communication (SPI); um conversor digital para analógico de 10 bits, o qual se baseia numa arquitetura de escalonamento binário por carga; um conversor tensão para corrente rail-to-rail e uma ponte H que direciona a corrente pela scaffold, cuja implementação se baseia no uso de portas de transmissão como comutadores. Resultados ao trabalho desenvolvido mostram que o circuito é capaz de estimular a scaffold com correntes entre 0 to 200μA com um erro na corrente de estimulação inferior a 0.75μA. O circuito é capaz ainda de fornecer uma corrente linear, na gama mencionada, a cargas com impedancias até 15k . Para cargas superiores o circuito é capaz de fornecer uma corrente linear, embora em gamas de correntes menores. O circuito implementado usa como tensão de alimentação 5V, tem um consumo médio de potência de 19.5mW e ocupa uma área de 0.19mm2. No decurso do trabalho desenvolvido foi utilizada uma tecnlogoia CMOS de 0.35um. A implementação e resultados foram obtidos com recurso ao software Cadence. Mestrado em Engenharia Eletrónica e Telecomunicações

This report is a brief analysis of the most comprehensive survey on conspiracy theories to date, using representative samples of the adult population in nine countries: France, Germany, Great Britain Hungary, Italy, Poland, Portugal, Sweden, and the United States of America. It is the first cross-national survey covering, simultaneously, matters related to conspiracy theory beliefs, general levels of trust and news consumption habits, including social media., Report produced for the project, Conspiracy and Democracy based at CRASSH, University of Cambridge. Project funded by the Leverhulme Trust (RP2012-C-017)

Islamophopia, in particular the conviction that the West is threatened by a process of Islamisation, is at the centre of the current wave of nativist and populist radical-right politics. This paper intends to outline the history of an imaginary present, the idea that “Western Civilization” is undergoing a process of Islamisation by which Muslims are demographically replacing the natives of the European continent with the collaboration of Western elites. The study will unveil the main elements of the narrative and shine a light on the beliefs, actions and goals of the agents and networks who advance it.

Defence date: 27 November 2017 Examining Board: Professor Donatella della Porta, European University Institute; Professor Hanspeter Kriesi, European University Institute; Professor Maha Abdelrahman, University of Cambridge; Professor Mario Diani, Università degli Studi di Trento In broad terms, this research is inspired by the founding questions of social movement studies: what triggers the process of recruitment, mobilisation and spread that leads to the demise or success of collective action? In particular, I was puzzled by the mobilisation and emergence of Egyptian contentious actors: how and why collective action evolved in the country from seemingly random and disconnected events and agents? Using Egypt as a case-study and the first decade of the twenty-first century as time frame, I set to solve this puzzle and find an answer to the leading research question: Does the emergence of Collective Action Networks in Egypt explain the increasing levels of contention and, ultimately, the 25 January uprising? This question focuses on the topic that gives title to the thesis, which is the relation between the hypothetical emergence of CANs and 1) a phase of heightened contention from 2000 to 2011 and 2) the revolutionary situation of 25 January, 2011. It also provides the basis to assess the manifestation of the two other relational patterns that appear in the subtitle of the thesis, namely dynamic protest waves and mobilisation spirals. In addressing the research question, I mixed quantitative and qualitative methods, combining protest event data collection and analysis, social network analysis with interviews. This allowed me to test if, how and why Collective Action Networks emerged and whether the revolutionary situation of 25 January 2011 was an unexpected spontaneous uprising or the natural outcome of a decade of sustained mobilisation. The main finding of this thesis is that, indeed, the intensification of contentious action in Egypt, between 2000 and 2011, was the product an emergent and increasingly complex Collective Action Network that stirred up protest waves and mobilisation spirals thus determining the Egyptian 25 January revolution.