Die Charcot-Marie-Tooth Typ 1 Erkrankungen sind eine genetisch heterogene Gruppe, aktuell nicht kurativ therapierbarer, erblicher Neuropathien des Peripheren Nervensystems. Klinische Manifestationen reichen von Sensibilitäts-störungen, verminderten Muskeleigenreflexen, sowie fortschreitenden Lähmungen, bis hin zu Muskelatrophie und bedeuten für die betroffenen Patienten eine starke Einschränkung der Lebensqualität. Anhand früherer Studien wurde Makrophagen, als Teil des angeborenen Immunsystems, eine entscheidende Rolle in der Pathogenese dreier CMT1-Unterformen zugeschrieben. Abgesehen von den morphologischen Manifestationen der demyelinisierenden CMT1-Erkrankungen, wie simultanes Auftreten von Dedifferenzierung, sowie Hypo-, und Demyelinisierung erkrankter Schwann-Zellen, sind pathologische Veränderungen der Domänengliederung der Ranvier’schen Schnürringe betroffener Nervenfasern ebenfalls von der Aktivierung pathogener Makrophagen abhängig. Auf der Basis verschiedener veröffentlichter Studien, welche sowohl demyelinisierende Erkrankungen des ZNS, aber auch primär durch axonale Schäden gekennzeichnete Erkrankungen des PNS beinhalten, besteht ein möglicher räumlicher Zusammenhang zwischen Architekturstörungen der RS und aktivierten pathogenen Mikrogliazellen bzw. Makrophagen. In dieser Studie konnte, anhand morphologischer Analysen von peripherem Nervengewebe, in Wt-Mäusen erstmals eine unerwartete präferentielle Lokalisation von Makrophagen im räumlichen Umfeld von RS beobachtet werden. Hierbei scheint, trotz des Fehlens einer direkten Zell-Zell-Interaktion zwischen Makrophagen und RS, vor allem im Hinblick auf die ebenfalls im räumlichen Umfeld von RS nachweisbare EZM und Fibroblasten, eine funktionelle Relevanz der assoziierten Makrophagen für die Aufrechterhaltung der Domänengliederung bzw. elektrophysiologischen Eigenschaften myelinisierter peripherer Nervenfasern denkbar. Im Gegensatz dazu wurde trotz der signifikanten Zunahme der Makrophagenanzahlen in den drei untersuchten CMT1-Mausmodellen keine erhöhte räumliche Assoziation mit den RS der mutierten Schwann-Zellen beobachtet. Vielmehr konnten anhand des Vergleiches mit wildtypischen Kontrollmäusen signifikant erniedrigte Assoziationsraten beider Strukturen in den CMT1-Modelltieren festgestellt werden. Folglich scheint die von der Einwanderung und Aktivierung pathogener Makrophagen abhängige Störung der Domänengliederung der RS der mutierten Schwann-Zellen, nicht durch eine direkte Interaktion bzw. räumliche Assoziation von Makrophagen mit RS ausgelöst zu werden. / The Charcot-Marie-Tooth neuropathies are a heterogenous group of inherited neuropathies oft he peripheral nervous system currenly incurable. Clinical symptoms vary from sensory loss, reduced tendon reflexes, muscular atrophy to progressive disability. According to different studies macrophages, as a part oft he innate immune system, play a crucial role in the pathogenesis of three different CMT-1 subtypes. Apart from morphological changes like dedifferentiation as well as hypo- and demyelination of diseased Schwann-cells, pathological alterations of nodes of Ranvier are also driven by activated marophages. As already described for demyelinating disoders oft he CNS, as well as neruodegenerative disorders oft he PNS, we investigated the spatial association of macrophages with diseased nodes of Ranvier. According to morphological analysis of peripheral nerve tissue this study is the first to describe an unexpected preferential spatial localization of macrophages near nodes of Ranvier in healthy nerves. Despite direct cell-cell interactions macrohages might play a functional role regarding the turnover of ECM and fibroblasts surrounding nodes of Ranvier, as well as the maintenance oft he architecture and electrophysiological features of peripheral nerve fibers.

Silicon-on-Insulator (SOI) micro-ring resonators (MRRs) are versatile elements in high-density integrated optics telecommunication systems. However, small inaccuracies in the fabrication process intensely deteriorate the response of SOI MRRs. By utilizing the racetrack resonator structures with strong coupling abilities, one can improve the fabrication tolerance. For the SOI racetrack resonators, the FSR is usually large. By introducing gratings into SOI racetrack resonators, the mutual mode coupling between the clockwise and counterclockwise modes can be induced and result in the resonance splitting. The grating-assisted SOI racetrack resonators can increase the operation wavelength and open up the possibility to overcome this limitation. In this thesis, we first use the 2-D FDTD method with the effective index method (EIM) to obtain the transmission spectra of the SOI racetrack resonators. The transmission spectra are then fitted by using the time-domain coupled mode theory (CMT) to obtain the quality factor and optical parameters of the SOI racetrack resonators. Next, we demonstrate the characteristics of mode splitting resulted from the mutual mode coupling between the clockwise and counterclockwise modes in the grating-assisted racetrack resonators by utilizing both the CMT and the 2-D FDTD method with the EIM. By tuning the grating configurations, such as the length or the structure of sidewall gratings, one can obtain the desired transmission spectrum of the grating-assisted racetrack resonators. Finally, we numerically investigate the temperature-dependent spectral characterics of the grating-assisted SOI racetrack resonator by taking the thermal-optic responce of the SOI materials into account. The thermal sensitivity of this device is 95.38 pm/¢XC, and the calculted properties can help the further designs based on the grating-assisted SOI racetrack resonators.

Submitted by João Arthur Martins (joao.arthur@ufpe.br) on 2015-03-11T18:40:22Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertaçao Lorena Marques.pdf: 2473408 bytes, checksum: ae5cba07c563d08350f8ddc5184cffee (MD5) / Approved for entry into archive by Daniella Sodre (daniella.sodre@ufpe.br) on 2015-03-13T13:10:17Z (GMT) No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertaçao Lorena Marques.pdf: 2473408 bytes, checksum: ae5cba07c563d08350f8ddc5184cffee (MD5) / Made available in DSpace on 2015-03-13T13:10:17Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertaçao Lorena Marques.pdf: 2473408 bytes, checksum: ae5cba07c563d08350f8ddc5184cffee (MD5) Previous issue date: 2013-02-25 / FACEPE / A crescente disponibilidade de acesso sem fio através de diferentes tecnologias (e.g., IEEE 802.11, IEEE 802.16 e 3G/UMTS) e o aumento do número de dispositivos com suporte a múltiplas interfaces heterogêneas possibilitam uma gama de oportunidades de conectividade sem fio aos usuários. Tradicionalmente, para este cenário, tem-se proposto algoritmos, protocolos e arquiteturas para a escolha da melhor rede de acordo com o perfil do usuário, característica da aplicação e da rede. Outra possibilidade de pesquisa, ainda não tão explorada no âmbito sem fio, é a distribuição de carga e conteúdo através de múltiplos caminhos simultâneos. Esta característica é conhecida como multihoming e pode dispor redundância de caminhos, oferecendo, dessa forma, certo grau de confiabilidade na rede. O grande desafio para implantação do multihoming em redes móveis heterogêneas decorre da instabilidade que esses ambientes possuem. O problema se agrava quando existem várias interfaces tentando se comunicar simultaneamente. O CMT (Concurrent Multipath Transfer) usa a característica multihoming do SCTP (Stream Control Transmission Protocol) para transmitir dados através de múltiplos caminhos fim-a-fim simultaneamente. No entanto, o CMT não possui um bom desempenho em redes com diferentes características, especialmente em se tratando de vídeo. Esta dissertação propõe o aCMT-UC (Adaptive CMT-User Centric), uma solução baseada em multihoming/centrada no usuário para a distribuição de carga em redes heterogêneas sem fio, tornando o CMT adaptável à dinâmica dos caminhos. O aCMT-UC prioriza os quadros de vídeo mais importantes que são transmitidos pelo melhor caminho sem fio. A distribuição de carga e priorização de vídeo são realizadas através da atribuição dinâmica de diferentes pesos para os caminhos sem fio, de acordo com um procedimento inteligente baseado em Lógica Fuzzy. Foram avaliadas métricas de Qualidade de Serviço e Experiência (QoS/QoE) em uma rede formada pelas tecnologias IEEE 802.11, IEEE 802.16 e 3G/UMTS em um simulador de redes (ns-2). Os resultados obtidos demonstram a eficácia da proposta em garantir QoS, bem como, o suporte adequado aos requisitos de tráfego de vídeo.

TCP and UDP are the most popular transport protocols used for end-end data transmission. The rapid growth of internet leads to development of many innovative applications in the current environment. Depending on the functionality of these applications, requirements of transport protocols are changing. TCP is known for its problems with Head Of Line blocking (HOL) and SYN attacks which gives reduced performance, and also doesn’t support Multi-Homing. SCTP is another transport layer protocol similar to TCP which provides end-end communication. It has some unique features like support for Multi-homing and multi-streaming. It also protects better from SYN attacks by using four-way hand shake mechanism during association establishment. As an extension to SCTP, CMT-SCTP was proposed to take full advantage of a multi-homed host by doing load sharing over multiple paths. SCTP is believed to be a next generation transport protocol. This thesis gives an overview of the SCTP protocol and its features focusing on analysing and testing of failover mechanisms provided by SCTP in multi-homed host, evaluating the transmission performance of SCTP vs TCP in a real network environment. This report also gives a theoretical analysis on how SCTP can mitigate SYN attacks by using four-way handshake mechanism and the state of art of CMT-SCTP.

No description available.

In presented diploma thesis is studied problematics of welding of high strength steels. This work also describes arc welding in protective atmosphere CMT Advanced. In experimental part of this work is CMT Advanced method compared with conventional arc welding in protective atmosphere in shortcut mode used for welding of Hardox 450 and Weldox 700 E. Comparing of mechanical properties of weld material are realized via transverse tensile testing and measuring of microhardness. Macrostructure and microstructure of weld was evaluated too. In the last part of this thesis is a brief economical assessment of both studied methods.

The research is focused on cladding of inconel 625 using the MAG - CMT method. It was found that welding without an oscillation does not create the necessary geometry to establish additional layers. When welding with an oscillation, it was researched that the current between 150 and 200 A appears most appropriate in the synergistic mode for welding inconel 625. The resulting weld bead was made at a current of 190 A with pulse dynamics correction set to -4 and correction of arc length to +10 and welding speed of 315 mm per minute.The weld bead was not ideal mainly due to insufficient height. The improvement of results could be achieved by set oscilation with fluent change in acceleration. Because of the time options and difficulty of programming it was used only constant speed for all experiments.

The development of welding technology is constantly going forward mainly due to the reduction of production costs and the costs of additional straightening of weldments due to the welding distortion. Therefore, the leading producers of welding machine are coming with new methods and technologies. One of the innovations is also the tandem technology CMT Twin from the company Fronius. The experiment carried out in the diploma thesis confirmed that this is a very cost effective process. The CMT Twin is from the point of view of production costs of the weld cheaper variant and bring less heat into the material compared with conventional welding. Application equipment CMT Twin requires industrial robot, so the method is predestined for the series up to mass production. The CMT Twin finds application, for example in the automotive and shipbuilding industry.

Background: Covid -19 pandemic affects how organizations and people operate. This crisisdiffers from previous ones due to its radical change. Organizations are threatened and strugglingto cope with the pandemic and making right decisions. This has put more attention on managementteam to address the issue at hand. This thesis explores how individuals experience crisis andmanaging it by decisions. Problem: Insufficient literature on how to make appropriate decisions in management team tocope with Covid-19 crisis. Purpose: This thesis purpose is to explore how crisis management team experience and cope withdecisions in the context of Covid-19. How individuals in a team overcome obstacles and makeappropriate decisions. Risks, uncertainty, stress, and time are previously known challenges formanagement teams. We aim to explore how these aspects affect the decision-making process. Research Question: How does crisis management team cope with Covid pandemic throughdecision-making? Method: This thesis has a qualitative research design and method of semi-structured interviewscarried out in a virtual environment due to Covid-19. Six informants have contributed to theempirical study. The empirical findings are presented in chapter 4 and analyzed by themes. Chapter5 provides discussion on the theoretical background and thesis findings, and finally conclusion inchapter 6. Conclusion: Crisis management encounters challenges with appropriate decisions for coping withCovid-19. However, our findings suggest that risk, ambiguity, and time factors are not majorchallenge and contradict this. This is due to the process of having an established crisis and makingdecisions collectively on all stages of a crisis. The most important stage of a crisis is the pre-stagewhere information is limited and guides the outcome of the whole process.

No description available.