Intraoperative Blutungskomplikationen sind bei der Versorgung von Patienten mit primärer rhegmatogener Netzhautablösung relativ selten. Bei den aufgetretenen Komplikationen handelte es sich fast ausschließlich um leichtere Blutungen, die intraoperativ gut zu beherrschen waren. Die Wahl der Antikoagulation hatte dabei keinen Einfluss auf die Wahrscheinlichkeit des Auftretens intraoperativer Blutungskomplikationen. Dies gilt sowohl für die Thrombozytenaggregationshemmer Acetylsalicylsäure und Clopidogrel als auch für die gerinnungshemmenden Substanzen Heparin und Phenprocoumon. Interessanterweise zeigte sich bei den mit Phenprocoumon behandelten Patienten keine Korrelation zwischen einem erniedrigten Quick-Wert und einer erhöhten intraoperativen Blutungsneigung. Bei den wenigen Patienten, bei denen es unter der Therapie mit Phenprocoumon zu einer Blutung während der Operation kam, lagen die Quick-Werte sogar eher im oberen Bereich. Wenn man nun bedenkt, dass es sich bei der rissbedingten Netzhautablösung um einen Notfall handelt und beim Zuwarten mit einer Progredienz der Ablösung zu rechnen ist, kann eine klare Empfehlung für die sofortige Operation trotz wirksamer Antikoagulation ausgesprochen werden. Untermauert wird dies noch durch die erhöhte Gefahr thromboembolischer Ereignisse, wenn eine indizierte Gerinnungshemmung perioperativ abgesetzt oder auf andere Substanzen umgestellt wird. Schließlich werden nur Patienten antikoaguliert, bei denen dies aufgrund von gravierenden Erkrankungen in der Vorgeschichte indiziert ist. Dazu gehören zum Beispiel abgelaufene tiefe Beinvenenthrombosen oder Embolien, Vorhofflimmern oder auch der Herzklappenersatz. Im Gegensatz zu den Ergebnissen für die Antikoagulation ergab sich eine Abhängigkeit der intraoperativen Blutungswahrscheinlichkeit von der Wahl des operativen Verfahrens. Die wenigsten Blutungen traten bei den rein eindellenden Operationen (Plomben und Cerclagen) auf. Bei den kombinierten Operationen (Plombe oder Cerclage in Kombination mit Pars plana Vitrektomie) lag die Komplikationsrate schon deutlich höher. Die höchste Rate intraoperativer Blutungskomplikationen zeigte sich bei den nicht-eindellenden Operationen (Pars plana Vitrektomien). Dabei war die Komplikationsrate bei den nicht-eindellenden Verfahren gegenüber den rein eindellenden Verfahren signifikant erhöht (p<0,001). Es kann also festgehalten werden, dass intraoperative Blutungen bei der Akutversorgung von Patienten mit rissbedingter Netzhautablösung selten sind und nicht im Zusammenhang mit der Einnahme von Gerinnungshemmern zu stehen scheinen. Die Wahl des Operationsverfahrens hingegen beeinflusst die Rate intraoperativer Blutungskomplikationen.

This Thesis reports on the integration of different modelling techniques to construct a unified and better constrained conceptual model of structural evolution of the Pico del Águila anticline (External Sierras, Southern Pyrenees, Spain). The structure is a well-known example of detachment fold, which exhibits a N-S structural trend, parallel to the direction of tectonic transport in the Southern Pyrenees. Based on field observations of an unevenly distributed Triassic décollement, analogue modelling show how to generate orogen-perpendicular structures which may result in transverse anticlines. Numerical models investigate the effect of a complex mechanical stratigraphy, characterized by an interlayering of competent and incompetent layers, plus syn-kinematic sedimentation in the fold growth. Based on field data and seismic interpretations, a 3D reconstruction and sequential geomechanical restoration of the Pico del Águila anticline reports the coexistence of multiple folding mechanisms occurring simultaneously in different units and structural domains of the fold, leading to a complex strain pattern that can not be assessed by simplistic kinematic 2D approaches. By integrating the presented models with the previous data in the region, we discuss about the benefits and drawbacks of each modelling technique and present an integrated model of structural evolution for the Pico del Águila anticline. This brings a better comprehension of the structure as well as the processes that drove the evolution of the N-S detachment anticlines in the External Sierras of the Southern Pyrenees. / L’anticlinal del Pico del Águila és un conegut exemple de plec de desenganxament amb sedimentació marina a fluvio-deltaica associada, amb una tendència estructural N-S, paral•lela a la direcció de transport tectònic dels Pirineus Meridionals. Basat en observacions de camp que indiquen una distribució heterogènia del nivell de desenganxament Triàsic, els models analògics mostren el procés de generació d’estructures perpendiculars al sistema orogènic que poden donar lloc als anticlinals N-S descrits a les Sierras Exteriores Aragonesas. Els models numèrics investiguen l’efecte d’una estratigrafia mecànica complexa, caracteritzada per una intercalació d’unitats competents i incomptetents (amb marcades diferències en el grau de competència, per tant) i de la sedimentació sin-cinemàtica en el creixement i evolució de l’anticlinal. Basat en dades de camp i interpretacions de perfils sísmics s’ha portat a terme una reconstrucció i restitució geomecànica tridimensional de l’anticlinal del Pico del Águila. D’aquestes se’n deriva la coexistència de de múltiples mecanismes de plegament actuant simultàniament en diferents unitats i dominis estructurals, la qual implica al seu torn un patró i distribució de la deformació que no poden ser avaluats mitjançant aproximacions o tècniques de modelització cinemàtiques o/i bidimensionals. S’integren també els resultats obtinguts a partir de les esmentades tècniques de modelització amb les dades i coneixements previs de la regió, es discuteixen els beneficis, desavantatges i limitacions de cadascuna d’aquestes tècniques de modelització, i es presenta un model integrat d’evolució estructural del Pico del Águila. Aquest anàlisi crític dels resultats i aquest esforç d’integració porten sense dubte cap a una millor comprensió de l’estructura i dels processos que menaren l’evolució dels plecs de desenganxament N-S de les Sierras Exteriores Aragonesas dels Pirineus Meridionals.

The Mount Somers Volcanic Group (MSVG) and Mandamus Igneous Complex (MIC) are the magmatic manifestations of the transition from convergence to extension at the Gondwana margin, which culminated in the separation of New Zealand from Australia and Antarctica. The MIC has been correlated both geochemically and temporally with the Central Marlborough Igneous Province (CMIP). The MSVG and CMIP are located in the Eastern Province of New Zealand. The MSVG is restricted to the Rakaia terrane, whereas the CMIP is restricted to the Pahau terrane. The Rakaia and Pahau terranes are thick accretionary complexes, which were strongly deformed as a result of prolonged subduction at the Gondwana margin. The Pahau terrane is the younger of the two and continued to be deposited and deformed until the abrupt cessation of subduction, which in the Marlborough sedimentary record occurred in the Motuan (100 - 105 Ma). Following the cessation of subduction, after an interval of 2-7 Ma of relative quiescence and subsidence of the Pahau terrane, the MSVG and MIC were erupted/emplaced. The production of MSVG and MIC magmas occurred simultaneously and the activity was of short-lived duration. SHRIMP geochronology yielded crystallisation ages of 97.0 ± 1.5 Ma to 98.0 ± 1.2 Ma from zircons separated from MSVG rhyolites. The SHRIMP ages are within error of the previously published Rb-Sr age for the MIC. The SHRIMP geochronology also confirmed the presence of inherited zircons which yielded ages consistent with their derivation from the Rakaia terrane. Ar-Ar geochronology confirmed the coeval nature of the MSVG and MIC magmatism, but yielded consistently younger ages (94.5 ± 3 Ma for the MSVG and 94.2 ± 1.7 Ma for the MIC). The systematic differences in ages obtained by SHRIMP and Ar-Ar are believed to be method-dependent. The MSVG comprises a calc-alkaline volcanic assemblage, which ranges in composition from basaltic-andesite lavas (SiO₂ = 54.5%) to high-silica rhyolites and ignimbrites (SiO₂ ≤ 78.1%). The MSVG had an original extent of at least 18 000 km². The magmas from the MSVG had high LILE/HFSE, high LILE/REE and moderately high LREE/HFSE which are characteristic of subduction derived magmas. Geochemical modelling suggests that the MSVG magmas were formed from partial melting of a subduction-modified mantle wedge, with high degrees of crustal assimilation. The assimilant had an isotopic composition similar to that of the Rakaia terrane, which is consistent with the geological setting of the MSVG. The MSVG has ⁸⁷Sr/⁸⁶Sri from 0.7055 to 0.7100 and ¹⁴³Nd/¹⁴⁴Ndi from 0.51254 to 0.51230 (ɛNd +0.5 to -4.2), which reflects varying degrees of contamination by Rakaia terrane. Radiogenic isotope modelling suggests that the MSVG end-members were derived from the same parent magma, which evolved through AFC processes from basaltic-andesite to rhyolite. The modelling strongly suggests that assimilation played a lesser role in the petrogenesis of the Malvern Hills magmas than in the petrogenesis of the other units. AFC modelling requires the degree of assimilation to increase as the magmas evolved. Oxygen isotope data are consistent with high degrees of crustal assimilation, and may indicate that the assimilant had higher ¹⁸O characteristics than the Rakaia terrane samples analysed. The MIC is an alkaline suite which ranges in composition from basalt and gabbro to syenite, trachyte and phono-tephrite. The MIC is interpreted to have formed from enriched asthenospheric mantle, with a composition similar to HIMU (²⁰⁶Pb/²⁰⁴Pbi ranges from 19.2 to 20.3). The samples range in isotopic composition from ⁸⁷Sr/⁸⁶Sri = 0.7030 to 0.7036, ¹⁴³Nd/¹⁴⁴Ndi = 0.51275 to 0.51268 (ɛNd +4.6 to +3.3). The range in isotopic composition is due to varying degrees of contamination by Pahau terrane, which reaches a maximum of 25% but in most samples is < 10%. The MIC is contaminated to a much lesser extent than the MSVG which is interpreted to be related to the thinner nature of the Pahau crust in the mid-Cretaceous. The latest phases of activity in the MIC were subjected to lower degrees of contamination which is interpreted to reflect the passage of magmas through pre-existing pathways. The onset of MSVG and CMIP magmatism coincided with the initiation of major rift-related depositional basins, and the eruption of the MSVG is demonstrably associated with normal faulting. The tectonic trigger responsible for the sudden onset of magmatism and rifting in the Eastern Province terranes was the detachment of the previously subducting slab following the cessation of subduction due to the arrival of the Hikurangi Plateau at the margin and the subsequent stalling of the Pacific spreading centre. The capture of the Gondwana margin led to the propogation of extension into the margin by the divergent Pacific plate. The ensuing extension aided the detachment of the subducting slab beneath the Eastern Province terranes. The slab-detachment promoted decompression melting of the sub-lithospheric mantle wedge to produce the MSVG magmas and triggered the ascent of asthenospheric mantle through the slab window, which melted through decompression to produce the CMIP magmatism. The asthenospheric mantle tapped by the slab detachment episode was highly enriched relative to N-MORB and is akin to the similar age HIMU-OIB affinity melts documented from Antarctica and Australia. The short-lived duration of activity is typical of slab-detachment related magmatism which occurs as a passive response to plate reconfiguration. The similarity in geochemistry of the MIC with OIB-affinity igneous centres in Australia and Antarctica implies an enriched mantle domain of large geographical extent. The distribution of relatively small volumes of OIB magmatism is suggestive of a fossil plume component, which was tapped in response to lithospheric extension producing relatively short-lived HIMU magmatism. The same fossil plume component has previously been implicated in the formation of the Cenozoic West Antarctic Rift System and may be responsible for the late Cretaceous magmatism in the Chatham Islands and Tertiary volcanics of the South Island of New Zealand.

In this work we generalize existing theory of low-energy collisions of atomic hydrogen with its anion. We extend the non-local resonance model for this system by adding new discrete state and two continua that are coupled with it. We calculate numerically cross sections for associative electron detachment process that is important for models of early universe. We add cross section for collision detachment and show spectra of outgoing electrons. We show how the isotopic effect is involved in studied collision. We also calculate charge transfer, elastic scattering cross sections, and reaction rates for hydrogen collisions with deuterium anion. We compare our results with recent experiments and we discuss their reliability. Powered by TCPDF (www.tcpdf.org)

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-03-02T23:01:37Z No. of bitstreams: 1 YgorBastosMesquitaMinoraDeAlmeida_DISSERT.pdf: 7592861 bytes, checksum: 1713383707550d5acbf0d5b871effb2a (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-03-04T22:10:21Z (GMT) No. of bitstreams: 1 YgorBastosMesquitaMinoraDeAlmeida_DISSERT.pdf: 7592861 bytes, checksum: 1713383707550d5acbf0d5b871effb2a (MD5) / Made available in DSpace on 2016-03-04T22:10:21Z (GMT). No. of bitstreams: 1 YgorBastosMesquitaMinoraDeAlmeida_DISSERT.pdf: 7592861 bytes, checksum: 1713383707550d5acbf0d5b871effb2a (MD5) Previous issue date: 2014-12-18 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico - CNPq / Atrav?s de fun??es de receptor migradas e empilhadas (phase-weightedstack), investigou-se a arquitetura crustal da Prov?ncia Borborema. Para isso, foram utilizados telessismos de ondas ? registrados em 64 esta??es sismogr?ficas distribu?das no Nordeste brasileiro, depois de aplicar um conjunto de modifica??es no algoritmo de empilhamento para corrigir inconsist?ncias detectadas no algoritmo original e melhorar sua efici?ncia computacional. A Prov?ncia Borborema representa a por??o mais oeste de um or?geno Neoproterozoico, que experimentou extens?o no Mesozoico, o que levou ? forma??o de um grande n?mero de bacias intracontinentais do tipo rifte, e, posteriormente, ? deriva continental. O Cenozoico foi marcado por processos de soerguimento topogr?fico, que poderia estar relacionado com vulcanismo, o que possibilitou a forma??o do Planalto da Borborema. Devido ? limitada compreens?o a respeito da arquitetura crustal da Prov?ncia, as rela??es de causa e efeito entre a topografia superficial, a extens?o Mesozoica e o soerguimento Cenozoico n?o s?o claras. O empilhamento de fun??es de receptor evidencia as convers?es ?? no limite entre a crosta e o manto, mostrando crosta espessa, entre 36 e 40 km na por??o sul do Planalto e crosta entre 30 e 32 km nas regi?es ao redor, incluindo o norte do Planalto. Essa mesma abordagem tamb?m revelou a presen?a de uma descontinuidade entre 9 e 18 km de profundidade, que tende a desaparecer em dire??o ao sul do Planalto, ? medida que a crosta se torna espessa. Dessa forma, argumenta-se que a crosta fina na Prov?ncia Borborema ? o resultado de processos de estiramento crustal durante o Mesozoico e que a descontinuidade intracrustal observada consiste num detachment de baixo ?ngulo, que atuou na acomoda??o da distens?o. A crosta espessa na por??o sul do Planalto seria, ent?o, um bloco com reologia mais resistente, que resistiu a deforma??o durante o Mesozoico, enquanto a crosta fina sob o norte do Planalto seria proveniente de uma bacia pret?rita, cuja crosta foi afinada durante o Mesozoico e soerguida durante o Cenozoico. / The crustal architecture of the Borborema Province was investigated through migration and stacking of receiver functions (phase-weighted-stack). The stacks were developed from teleseismic ?-waves recorded at 64 seismological stations distributed throughout Northeast Brazil, after applying a number of modifications to the stacking algorithm that corrected inconsistencies in the original algorithm and improved its computational efficiency. The Borborema Province is the westernmost portion of a Neoproterozoic orogen that experienced extension in the Mesozoic, leading to the formation of a number of intracontinental rift basins and, eventually, to the continental drift. The Cenozoic was marked by topographic uplift of the Province, perhaps related to coeval episodes of volcanism, which resulted in the formation of the Borborema Plateau. Due to limited understanding of the crustal architecture of the Province, the causal relationships between surface topography, Mesozoic extension, and Cenozoic uplift are poorly understood. The receiver function stacks highlight ?? conversions from the crust-mantle boundary that demonstrate a thick crust between 36 and 40 km in the southern Plateau, and crust between 30 and 32 km in the regions around, including the northern Plateau. The receiver function stacks also revealed the presence of a discontinuity between 9 and 18 km depth that tends to fade away towards the southern Plateau as the crust thickens. It is argued that the thin crust in the Borborema Province is the result of crustal stretching during Mesozoic times, and that the intracrustal discontinuity marks the location of a lowangle detachment zone that accommodated extension within the crust. The thick crust in the southern Plateau would then be a rheologically strong block that resisted deformation during the Mesozoic, while the thin crust beneath the northern Plateau would be a portion of a formerly depressed crust that experienced uplifted during the Cenozoic.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O presente trabalho consiste em um estudo crítico do romance Sem tecto, entre ruínas, de Augusto Abelaira. Inicialmente é feita a análise sobre as possíveis consequências de uma apreensão descontínua e material do tempo, seus efeitos nas relações entre o protagonista e seu mundo, que se apresentam sob a forma de tédio e paralisia. Para a crítica proposta foram retomados conceitos descontinuidade e homogeneidade apresentados pelo filósofo Henri Bergson, além da noção de desligamento e desejo demonstrados pela sociologia de Zigmunt Bauman. O próximo alvo contemplado na pesquisa é a presença da memória e da lembrança indicados sob o ponto de vista contínuo do tempo, também analisados à luz da filosofia de Bergson, além do pensamento de Gilles Deleuze. A partir desse caminho investigativo é possível pensar a condição do protagonista como um confronto de si, uma experiência do tempo que traz uma revelação mediante a condição de ser tarde demais / This work provides a critical analysis on the novel Sem tecto, entre ruínas by Augusto Abelaira. In the first instance this study begans with the analysis of the possible consequences aroused by a material apprehension of time as well as its impact on relations between the protagonist and the world in which he lives, wich are presented by the feelings of boredom and paralysis. For the proposed work were taken up concepts of discontinuance and homogeneity created by the philosopher Henri Bergson, as well as the notion of detachment and desire demonstrated by the sociology of Zigmunt Bauman. The next target contemplated in the research is the presence of memory and recollection indicated under the point of view of continuous time, also examined by the philosophy of Bergson, in addition to the thought of Gilles Deleuze. Based on this investigative path is possible to consider the condition of the protagonist as a confront with itself, an experience of time that brings up a revelation upon the condition of being too late

Made available in DSpace on 2016-03-15T19:36:39Z (GMT). No. of bitstreams: 1 Eduardo Nocera.pdf: 12755331 bytes, checksum: 08a19b90827b2e4f2954b2f799e3d18d (MD5) Previous issue date: 2013-09-19 / MAHLE / Piston rings are metal parts which, when installed on the pistons in the cylinders of the engine, become circular with variable pressure and self-expansive, providing a movable seal between the combustion chamber and the crankcase. These components are subjected to intense functional demand, being asked to submit a low wear rate and maintain their structural and functional integrity under high temperatures and pressures. Due to these requirements, the technique is known of providing up-to-face contact with coatings or surface treatments to improve wear. Currently the majority of applications in the compression rings are martensitic stainless steels. These rings have their tribological properties improved by gas nitriding treatment which gives the steel surface intermediate properties between metallic and ceramic materials with high resistance to adhesive wear, as well as to wear by abrasion. This technology has been applied since the 90s with great success and high market penetration. With demand growing for reducing emissions was introduced in the market the Otto cycle engines with bifuel, better known as Flex engines. The principle of operation of these engines is the use of gasoline and ethanol at any mixing. The compression ratio of the piston is optimized for gasoline and not optimized for ethanol, since the latter does not have limitations to the phenomenon of detonation and this fact makes it occurs more Ethanol injection into the combustion chamber providing an improper fuel does not wash burnt in the cylinder wall. The result was the creation of a different tribological system in the area of operation of the rings where the nitrided layer began to suffer a detachment. This study aimed to find a solution for this detachment, where the nitride layer was changed. The modification consisted in decreasing the precipitation of carbides in the grain boundaries through migration carbon more to the core of the ring making it more robust to cracks and less susceptible to hydrogen embrittlement. Was created two nitriding stages, one richer in nitrogen which provides the wear resistance required for applying and the second stage causes the carbon to become more concentrated in the core hindering the generation of cracks and, consequently, the detachment. There was a decrease in the hardness of the nitrided layer without deteriorating the wear resistance, creating a unique solution and extending the life of this technology. / Os Anéis de Pistão são peças de metal que, quando instaladas nos pistões dentro dos cilindros dos motores, tornam-se circulares com pressão variável e auto-expansivas, proporcionando uma vedação móvel entre a câmara de combustão e o carter do motor. Estes componentes são submetidos à intensa demanda funcional, sendo solicitados a apresentarem uma baixa taxa de desgaste e a manterem sua integridade estrutural e funcional sob temperaturas e pressões elevadas. Em função destas exigências, é conhecida a técnica de prover-se a face de contato com o cilindro destes componentes revestimentos ou tratamentos de superfície para melhorar a resistência ao desgaste. Atualmente grande parte das aplicações nos anéis de compressão são em aços inoxidáveis martensíticos. Estes anéis têm suas propriedades tribológicas melhoradas pelo tratamento de nitretação gasosa o qual confere ao aço propriedades superficiais intermediárias entre os materiais metálicos e cerâmicos, com alta resistência ao desgaste adesivo, assim como ao desgaste por abrasão. Esta tecnologia vem sendo aplicada desde os anos 90 com absoluto sucesso e alta penetração de mercado. Com a demanda por redução de emissões crescendo foi introduzido no mercado os motores de ciclo Otto bicombustíveis, mais conhecidos como motores flex. O princípio de funcionamento destes motores é a utilização de gasolina e etanol em qualquer mistura. A taxa de compressão do Pistão é otimizada para gasolina e não otimizada para o Etanol, pois este último não possui limitações para o fenômeno de detonação e este fato faz com que ocorra mais injeção de Etanol na câmara de combustão proporcionando uma indevida lavagem de combustível não queimado na parede do cilindro. A consequência foi a criação de um tribo sistema diferente na região de funcionamento dos Anéis onde a camada nitretada começou a sofrer um destacamento. Este trabalho visou buscar uma solução para este destacamento, onde a camada nitretada foi alterada. A alteração consistiu em diminuir a precipitação de carbonetos nas fronteiras dos grãos através da migração do carbono para o núcleo do anel deixando-o mais robusto à nucleação de trincas e menos susceptível a fragilização por hidrogênio. Foram criados dois estágios de nitretação, sendo o primeiro estágio mais rico em nitrogênio o qual confere ao anel a resistência ao desgaste necessária para a aplicação, e o segundo estágio faz com que o carbono fique mais concentrado no núcleo. O problema de destacamento foi resolvido onde houve uma diminuição na dureza da camada nitretada sem a deterioração da resistência ao desgaste do anel, criando uma solução única e estendendo a vida desta tecnologia sem aumento de custos.

Abstract Date: 2017-06-05 Level: Master thesis in Business Administration, 15 cr Institution: School of Business, Society and Engineering, Mälardalen University Authors:                             Nilsson, Isabella                  Ulriksson, Jennifer                                            920507                                930119 Title: Connection versus Recovery? Communication technology in the modern working life.  Tutor: Magnus Hoppe Keywords: Smartphones, Information and communication technology, Boundary control, Psychological detachment, Work-Life Conflict, Stress, Job-Demand-Control. Research question: How do managers handle the positive and negative effects of communication technology? Purpose: The aim of this study is to critically analyse how managers in Sweden regulate the use of communication technology and how they perceive the effects of communication technology on the modern workplace. This contributes to an understanding regarding whether communication technology should be handled based on individuals being either digitally connected or able to mentally recover from work. Method: This study is of a qualitative approach, where semi-structured interviews were conducted with eight managers who is/ or has been, in charge of personnel. The study has a deductive approach and thus has its base in theory. Theories have consequently been used in the construction of the interview questions as well as in the creation of Modell 1.0. Conclusion: Policies restricting the use of communication technology is not desirable according to managers, this is due to it being a prerequisite for the working life of 2017. ‘Connection’ and ‘recovery’ are not dichotomies for all employees. Policies can be of use for employees who need help managing the boundaries between work and family. However, to reach a solution regarding the negative effects of communication technology, efforts should be put into the organizational culture rather than policies, which is depicted in Model 2.0. In that way, negative effects of communication technology can be fought off without risking the positive effects. Communication technology should not be handled based on the assumption that individuals are either digitally connected or able to mentally recover from work.

No description available.

In nature, cells are not randomly clustered to form tissues. The tissue is a more complicated system with functions that go beyond what any single cell type could accomplish. While studying single-cell mechanics and dynamics is relevant from an investigative point of view, this approach loses, or fail to gather information about the tissue. The tissue investigated in this study is the neurosensory retina which seeing as extension of the brain is a very convenient model for the central nervous system due to its accessibility. The retina is constantly subjected to different mechanical stresses from development to adulthood. Although the majority of the phenomena where mechanical stresses are involved are well-studied, the mechanics behind them is not well understood. However, knowledge about the ability of the retina to adjust to mechanical stresses is essential, for example, for improving retinal surgery. Establishing a method to mechanically probe the retina is a challenge due to the extremely delicate nature of this multilayered neural tissue and to the short-time survival ex vivo. The organotypic tissue culture is a powerful tool because it allows to maintain with high accuracy the complex multicellular anatomy and the microenvironment of the original tissue. One of the limitations of the organotypic culture techniques has been until recently due to the ability to use only post-natal/juvenile tissues for long-term culture. The importance of using adult tissue is incontestable when the investigation focuses on age-related pathologies such as vitreous shrinkage or macula degeneration. In this work, TiO2 nanotube arrays are presented as the innovative substrate for long-term organotypic culture of adult neural tissue. The retinal whole-mount of adult guinea pig and the brain slices of adult mouse were cultures for 14 days without showing any sign of edema or swelling. Furthermore, in order to study the behavior of the retinal tissue under shear stress new set-ups were designed. For the first time, the behavior of the retinal layers were observed showing that the retina does not act as an homogeneous material in response to an applied stress. The methods developed here can be used for future quantitative studies, to provide an exact knowledge of retinal biomechanics which will help retinal surgeons to optimize their methods.