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Investigation of ESD Protection Devices in High-speed Digital SystemJan, Yi-Lun 03 July 2005 (has links)
In the trends of high clock rate, lower voltage, small volume, and portable requirement for present electric products, the noise immunity of high speed digital circuit becomes a critical factor for system designer. ESD problem becomes more and more important for electric products because of the triboelectricity caused by human body and synthetic material. It¡¦s an important issue for designer to understand the ESD phenomena in grounding and floating system accurately.
In this thesis, a reliable setup for the ESD measurement is proposed both in grounding and floating systems. ESD behavior and protection devices are studied in detail and a corresponding SPICE model is built up for simulation validation.
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New Type Mechanical Overload Protection Devices Design by Patent Design Around and Biomimetic ConceptsLee, Dau 11 February 2011 (has links)
Patent information can provide up-to-date technological data that accelerate the development of new products and the improvement of technology. They also can provide a most useful survey of known solution possibilities, which avoid duplication and the resources wasting. Therefore, this study focuses on the patent searching and analysis of the mechanical overload protection devices. Patent information are fed into computer databases and stored for design around activities.
The connections between biology and technology be called as bionics or biomimetics can lead to very useful and novel technical solution. This study introduced special underwater creatures ¡§snapping shrimp¡¨ which have a large claw can generate the snapping action. This action inspires us to find a new technical solution that using the liquid cohesion to store and release the energy. In the end, using the patent information and the new solution to achieve the new design of mechanical overload protection devices, include ¡§Force-Type¡¨ and ¡§Torque-Type¡¨.
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Överspänningsskydd / Surge ProtectionHilleberg, Jesper, Falakeh, Sam January 2021 (has links)
Solar Bora is a company that works to bring electricity to small villages in Africa to help them save time in cooking and other things that we nowadays forget about. Africa is the continent with the most thunder strikes in the entire world, and it is therefore common that electronics get affected by this. Our work helps to protect against the surges caused by the electromagnetic pulses that are made by nearby thunder strikes. A surge protection is made using two surge protection devices, a metal oxide varistor and a transient voltage suppression diode in parallel. These are made to short-circuit large transients to ground to protect a circuit from the damaging transient. To test the circuit, we charged a capacitor up to 720 volts and then short-circuited it against the protective circuit to create a high voltage transient. The protective circuit managed to protect against the created transient, but a larger transient would be preferable to see the circuit’s full potential. / Solar Bora är ett företag som jobbar med att skapa energi till de små byar i Afrika som inte har tillgång till det, för att hjälpa dem spara tid vid matlagning och andra vardagssysslor som vi tar för givet. Afrika är den kontinent som har mest åsknedslag i hela världen och det är därför vanligt att elektronik skadas utav åsknedslagen. Arbetet som utförs kommer hjälpa skydda den elektroniken tillhörande Solar Boras system mot överspänningar orsakade av de elektromagnetiska pulserna från närliggande åsknedslag. Ett överspänningsskydd skapas genom användningen av en metal oxide varistor och en transient voltage suppression diode parallellkopplat. Dessa kortsluter stora transienter till jord för att skydda kretsen mot den skadande transienten. För att testa kretsen användes en uppladdad kondensator på 720V som sedan kortslöts mot kretsen för att skapa en högspänningstransient. Skyddet lyckades att dämpa transienten som tänkt men större transienter skulle behövts för att visa kretsens fulla potential.
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Prédiction objective de l'effet des systèmes tactiques de communication et protection sur les performances de localisation sonore / Objective prediction of the effect of tactical communication and protective systems on sound localization performanceJoubaud, Thomas 15 September 2017 (has links)
Dans de nombreuses situations civiles ou militaires, la protection de l'audition du personnel est cruciale. La perception et l'interprétation de l'environnement sonore par l'auditeur doivent cependant être préservées. Les Systèmes Tactiques de Communication et Protection (TCAPS) sont des protections auditives qui, à la fois, protègent suffisamment les oreilles de l'auditeur contre les bruits dangereux, et préservent l'intelligibilité, permettant ainsi la communication vocale à bas niveau. Des études précédentes ont cependant démontré que les TCAPS continuent de détériorer la perception de l'environnement sonore de l'auditeur, en particulier sa capacité à localiser les sources sonores. Sur le plan horizontal, la dégradation des indices acoustiques empêchant, en temps normal, l'auditeur de confondre les sources avant et arrière, en est la principale explication. Dans ce travail de thèse, une expérience subjective de localisation sonore est conduite avec six TCAPS: deux bouchons d'oreille passifs, deux bouchons d'oreilles actifs et deux casques actifs. Si aucun protecteur ne permet de retrouver les performances de la condition d'écoute normale, l'expérience permet de classifier les TCAPS du point de vue de la localisation sonore: les performances des bouchons passifs sont meilleures que celles des bouchons actifs, et les casques actifs engendrent les plus mauvaises performances. Dans le cadre de la conception et de l'évaluation des TCAPS, une méthode prédisant leur dégradation des performances de localisation sonore, basée sur des mesures électroacoustiques, serait plus adaptée que des expériences comportementales très chronophages. Dans ce contexte, deux méthodes basées sur les Fonctions de Transfert Relatives à la Tête (HRTF) mesurées sur tête artificielle sont étudiées: un processus d'appariement et un réseau de neurones à trois couches. Ils sont optimisés pour reproduire les performances de localisation humaine en condition d'écoute normale. Les méthodes sont ensuite appliquées aux HRTF mesurées avec les six TCAPS, et prédisent des probabilités de localisation en fonction de la position. Comparé aux résultats de l'expérience subjective, le réseau de neurones prédit des performances réalistes avec les bouchons d'oreille, mais surestime les erreurs avec les casques. Le modèle d'appariement prédit correctement les performances de localisation. Toutefois, la vraisemblance de ses distributions de probabilité avec les observations subjectives demeure plus faible que celle du réseau de neurones. Pour finir, les deux méthodes développées dans cette étude sont indépendantes de la tête artificielle utilisée, et peuvent être utilisées pour évaluer non seulement des prototypes de TCAPS, mais aussi des prothèses auditives. / In many civilian or military situations, hearing protection is of major importance. The listener's acoustical situational awareness must however also be preserved. Tactical Communication and Protective Systems (TCAPS) are hearing protection devices that sufficiently protect the listener's ears from hazardous sounds and preserve speech intelligibility, thus allowing low-level speech communication. However, previous studies demonstrated that TCAPS still deteriorate the listener's situational awareness, in particular the ability to locate sound sources. On the horizontal plane, this is mainly explained by the degradation of the acoustical cues normally preventing the listener from making front-back confusions. In the present PhD work, a behavioral sound localization experiment is conducted with six TCAPS: two passive and two active earplugs, and two active earmuffs. The performance in open ear condition is not retrieved with any protector, but the experiment ranks the TCAPS by type: passive earplugs lead to better performance than active earplugs, and active earmuffs induce the worst performance. As part of TCAPS development and assessment, a method predicting the protector-induced degradation of the sound localization capability, and based on electroacoustic measurements, would be more suitable than time-consuming behavioral experiments. In this context, two methods based on Head-Related Transfer Functions (HRTFs) measured on an artificial head are investigated: a template-matching model and a three-layer neural network. They are optimized to fit human sound localization performance in open ear condition. The methods are applied to the HRTFs measured with the six TCAPS, providing position-dependent localization probabilities. Compared with the behavioral results, the neural network predicts realistic performances with earplugs, but overestimates errors with earmuffs. The template-matching model predicts human performance well. However, the likelihood of the resulting probability distributions with the behavioral observations is lower than that of the neural network. Finally, both methods developed in this study are independent of the artificial head used, and can be applied to assess not only TCAPS prototypes, but also hearing aids.
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<strong>Enhancing Construction Workers Safety: The Design and Implementation of Interactive-Motivational Noise-Cancelling Headphones</strong>Shima Jahani (16648824) 31 July 2023 (has links)
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<p>Noise-induced hearing loss (NIHL) is a significant occupational health concern in the construction industry, necessitating effective hearing protection for workers. This project explores the detrimental consequences of environmental pollutants, specifically noise pollution common in construction settings. The research incorporates user interviews with construction workers and managers to identify challenges and motivations surrounding the use of hearing protection devices.</p>
<p>My findings underscore the necessity of addressing pollution in the construction industry to safeguard the well-being of workers. Noise pollution emerges as a primary concern, leading to hearing loss, stress, decreased productivity, and safety hazards. The research revealed that workers grapple with obstacles, including discomfort, lack of awareness, and cost barriers, while also recognizing driving forces, including fear of hearing loss and the encouragement of supervisors. The design process involved thorough research, including a literature review, competitive analysis, and semi-structured user interviews, resulting in an advanced hearing protection device that prioritizes effective communication, cleanliness, and user comfort. The final product incorporates innovative features such as lighting indicators, a compact charging case, strategically positioned buttons, secure fit with magnets, and a range of color options. Furthermore, the accompanying application features customizable ambient sounds, performance feedback, and gamification elements.</p>
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Alterações de difusão e perfusão cerebral por RM em angioplastia carotídea com \"stent\" sob proteção cerebral por filtros / Changes in diffusion and perfusion weighted magnetic resonance imaging in carotid angioplasty with stenting under cerebral protection by filtersSá Júnior, Antenor Tavares de 09 October 2009 (has links)
INTRODUÇÃO: A angioplastia carotídea com stent (ACS) sob proteção cerebral é opção terapêutica em pacientes com estenose carotídea. Existe o risco de embolia apesar da utilização do filtro e as modificações na perfusão cerebral após tratamento da estenose carotídea não são claras. O propósito deste estudo é avaliar, após ACS sob proteção cerebral por filtros, modificações nas seqüências de RM de difusão (DWI) e perfusão (PWI), correlacionando-as com os aspectos técnicos da ACS, com as características da estenose e com dados demográficos dos pacientes. MÉTODO: Trinta e seis pacientes portadores de estenose carotídea com idade média de 72,08 anos foram submetidos a exame de RM um dia antes e até 72 horas após a ACS com filtro de proteção. Todos os pacientes eram assintomáticos após a ACS. Áreas de restrição na DWI após a ACS foram correlacionadas com aspectos demográficos, com aspectos da técnica de angioplastia e com a presença de infartos prévios por RM. Os parâmetros CBV volume sanguíneo cerebral, MTT tempo de trânsito médio e TTP tempo para o pico são empregados para análise por PWI. RESULTADOS: Na DWI, 18 de 36 (50,00%) pacientes apresentaram novos focos (NF) de restrição na DWI após ACS. Todos os NF foram clinicamente silenciosos (100%). Estes NF eram localizados em território cerebral nutrido pela artéria carótida submetida à ACS em 77,19% e menores que 10 mm em 91,53%. Os NF em território cerebral não irrigado pela artéria carótida submetida à angioplastia correspondiam a 22,81% destes. A presença de infartos cerebrais prévios na RM foi o único fator com influência no aparecimento de NF (p=0,037). Fatores demográficos e aspectos relacionados com a técnica de angioplastia não tiveram importância na gênese dos NF. Na PWI foi observada melhora nos parâmetros temporais TTP (p<0,001) e MTT (p=0,019) quando comparados de forma normalizada em relação ao território contralateral. CONCLUSÃO: Os novos focos de restrição na DWI após ACS (NF) foram mais comuns no território ipsilateral (77,19%), no entanto houve NF no território contralateral à ACS (22,81%), possivelmente, associados ao cateterismo diagnóstico. Os NF, na sua maioria, são de pequeno diâmetro (<10 mm em 91,53%). Melhora precoce na PWI, observada nos dados normalizados, foi demonstrada nos parâmetros temporais (TTP e MTT). / INTRODUCTION: Carotid angioplasty with stent (CAS) under cerebral protection is a therapeutic option in patients with carotid stenosis. There is a risk of embolism even with a filter, and changes in cerebral perfusion after treatment are not clearly understood. The purpose of this study was to evaluate changes in diffusion- (DWI) and perfusion- (PWI) weighted magnetic resonance imaging (MRI) sequences correlating them with the technical aspects of CAS, stenosis characteristics and patient demographic data. METHODS: Thirty-six carotid stenosis patients with an mean age of 72.08 years were submitted to MRI exam one day before and up to 72 hours after CAS with filter protection. All patients were asymptomatic after CAS. Areas of restriction on DWI were correlated to demographic aspects, technique of angioplasty as well the presence of previous stroke by MRI. The parameters, CBV - cerebral blood volume; MTT - mean transit time, and TTP- time to peak, are used for PWI analysis. RESULTS: Eighteen of the 36 patients (50.00%) presented new focus (NF) of restriction by DWI after CAS. All new focus were clinically silent. The NF were located in the cerebral area fed by the carotid artery submitted to CAS in 77.19% and smaller than 10mm in 91.53%. NF in cerebral area not irrigated by carotid artery submitted by angioplasty correspond to 22,81 %. The presence of previous ischemic lesion on MRI was the only factor which influenced the appearance of NF (p=0.037). Demographic factors and aspects related to angioplasty technique had no importance on NF genesis. Improvement in PWI timing parameters - TTP (p<0.001) and MTT (p=0.019) were observed in relation to the contralateral territory (normalized data). CONCLUSION: The restriction NF in the DWI after CAS are more common in the ipsilateral territory (77.19%), however there were some NF in the contralateral territory to the CAS (22.81%), possibly associated with diagnostic catheterization. Most of the NF were small in diameter (<10mm in 91.53%). Short-term improvement in PWI were demonstrated by normalized timing parameters (TTP and MTT).
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Concreto com fresado asf?ltico aplicado em dispositivos de prote??o e drenagem de obras vi?rias / Concrete with recycled asphalt pavement applied in protection devices and drainage of road worksRuiz, Adilson Nunes 07 February 2017 (has links)
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Previous issue date: 2017-02-07 / Funda??o de Amparo ? Pesquisa do Estado de S?o Paulo - FAPESP / In view of the large volume of waste generated by the construction industry coupled with the growing understanding of environmental preservation by the population, it was necessary to carry out studies with the firm intention of reusing these wastes. This work focuses on the residues generated in the area of road pavement construction, especially those resulting from the maintenance, restoration and improvement of roads paved with asphalt concrete. As the use of this material is not always carried out in a technical and adequate way, even though several studies are directed to the good technique of using recycled asphalt pavement, this work intends to present another technical form for the application of this important residue, to use in the construction of rigid concrete barriers and in gutters, half wire and gutters. These services normally run within the road works, that is, it aims to keep the material generated within the limits of the generating source. In order to achieve this, studies focused on meeting the technical specifications of the National Department of Infrastructure and Transport (DNIT) and the Department of Roads of the State of S?o Paulo (DER-SP), minimizing the output of milling from the generating source, considering that these public agencies are the main sources of this waste and performers of the services for which it is intended. This study compared the physical characteristics of conventional concrete and concrete with embedded asphalt milling, thus evaluating its technical, economic feasibility and environmental. The study was carried out in concrete with a characteristic compressive strength of 25MPa, intended for road safety elements, and at 20MPa for surface drainage elements. It was observed that the increase of recycled asphalt pavement in the concrete mixture directly influences the mechanical resistance, reducing its resistant capacity. When analyzing the substitution content of recycled asphalt pavement in the mix, it was found that percentages higher than 15% substantially affect the concrete's strength properties. The concrete with recycled asphalt pavement presents less rise and absorption of water by capillarity, as well as less absorption in the test of immersion, important qualities for mixtures that will be destined to the manufacture of structures that will be exposed to the elements or the contact with the water. The use of this residue in the concrete generates reduction in the cost of manufacture, besides providing reduction of the emission of greenhouse gases (CO2). In Brazil, it can be estimated that the use of asphalt milling in the concretes studied, can generate the approximate annual reduction of 270 thousand tCO2, besides saving approximately US$ 97 million/year through the sale of CO2 ("green" income) And the reduction of costs with the acquisition of natural raw materials extracted from deposits (sand and crushed stone), as well as to finance with this amount the construction of approximately 23 thousand popular residences of 40m2. / Tendo em vista o grande volume gerado de res?duos pela ind?stria da constru??o aliado ao fato do crescente entendimento pela popula??o da preserva??o ambiental, fez-se necess?ria a realiza??o de estudos com o firme prop?sito de reutiliz?-los. Este trabalho foca no res?duo gerado na ?rea da constru??o de pavimenta??o vi?ria, principalmente naqueles advindos das obras de manuten??o, restaura??o e melhoria do leito vi?rio pavimentado revestido com concreto asf?ltico. Como a utiliza??o deste material ? realizada nem sempre de forma t?cnica e adequada, mesmo tendo diversos estudos direcionados ? boa t?cnica de utiliza??o do fresado asf?ltico, este trabalho tem a pretens?o de apresentar mais uma forma t?cnica para a aplica??o deste importante res?duo, o de utilizar na constru??o de barreiras r?gidas de concreto e em canaletas, meios fio e sarjetas. Servi?os estes normalmente executados dentro das obras vi?rias, ou seja, visa manter o material gerado dentro dos limites da fonte geradora. Para isso, foram realizados estudos focados em atender as especifica??es t?cnicas do Departamento Nacional de Infraestrutura e Transporte (DNIT) e do Departamento de Estradas de Rodagem do Estado de S?o Paulo (DER-SP) em parte das obras de seguran?a vi?ria e drenagem, tendo em vista que estes ?rg?os p?blicos tem o dom?nio das principais fontes geradoras deste res?duo e s?o executores dos servi?os ao qual se destina. Este estudo comparou as caracter?sticas f?sicas do concreto convencional e do concreto com fresado asf?ltico incorporado, avaliando assim a sua viabilidade t?cnica, econ?mica e ambiental. O estudo foi realizado em concreto com resist?ncia caracter?stica ? compress?o de 25MPa, destinado a elementos de seguran?a vi?ria, e com 20MPa, para os elementos de drenagem superficial. Foi constatado que o incremento de fresado asf?ltico na mistura do concreto influencia diretamente nas resist?ncias mec?nicas, reduzindo sua capacidade resistente. Ao analisar o teor de substitui??o de fresado asf?ltico na mistura, foi constatado que percentuais superiores a 15% afetam substancialmente as propriedades mec?nicas do concreto. O concreto com fresado asf?ltico apresenta menor ascens?o e absor??o de ?gua por capilaridade, bem como menor absor??o no ensaio de imers?o, qualidades importantes para misturas que ser?o destinadas ? fabrica??o de estruturas que ficar?o expostas ?s intemp?ries ou ao contato com a ?gua. O uso deste res?duo no concreto gera redu??o no custo de fabrica??o, al?m de proporcionar redu??o da emiss?o de gases do efeito estufa (CO2). No Brasil, pode-se estimar que o uso do fresado asf?ltico nos concretos estudados, pode gerar a redu??o anual aproximada de 270mil tCO2, al?m de possibilitar economia aproximada de US$ 97 milh?es/ano atrav?s da comercializa??o do CO2 (renda ?verde?) e da redu??o de custos com a aquisi??o de mat?rias primas naturais extra?das de jazidas (areia e pedra britada), bem como financiar com este valor a constru??o de aproximadamente 23mil resid?ncias populares de 40m?.
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Alterações de difusão e perfusão cerebral por RM em angioplastia carotídea com \"stent\" sob proteção cerebral por filtros / Changes in diffusion and perfusion weighted magnetic resonance imaging in carotid angioplasty with stenting under cerebral protection by filtersAntenor Tavares de Sá Júnior 09 October 2009 (has links)
INTRODUÇÃO: A angioplastia carotídea com stent (ACS) sob proteção cerebral é opção terapêutica em pacientes com estenose carotídea. Existe o risco de embolia apesar da utilização do filtro e as modificações na perfusão cerebral após tratamento da estenose carotídea não são claras. O propósito deste estudo é avaliar, após ACS sob proteção cerebral por filtros, modificações nas seqüências de RM de difusão (DWI) e perfusão (PWI), correlacionando-as com os aspectos técnicos da ACS, com as características da estenose e com dados demográficos dos pacientes. MÉTODO: Trinta e seis pacientes portadores de estenose carotídea com idade média de 72,08 anos foram submetidos a exame de RM um dia antes e até 72 horas após a ACS com filtro de proteção. Todos os pacientes eram assintomáticos após a ACS. Áreas de restrição na DWI após a ACS foram correlacionadas com aspectos demográficos, com aspectos da técnica de angioplastia e com a presença de infartos prévios por RM. Os parâmetros CBV volume sanguíneo cerebral, MTT tempo de trânsito médio e TTP tempo para o pico são empregados para análise por PWI. RESULTADOS: Na DWI, 18 de 36 (50,00%) pacientes apresentaram novos focos (NF) de restrição na DWI após ACS. Todos os NF foram clinicamente silenciosos (100%). Estes NF eram localizados em território cerebral nutrido pela artéria carótida submetida à ACS em 77,19% e menores que 10 mm em 91,53%. Os NF em território cerebral não irrigado pela artéria carótida submetida à angioplastia correspondiam a 22,81% destes. A presença de infartos cerebrais prévios na RM foi o único fator com influência no aparecimento de NF (p=0,037). Fatores demográficos e aspectos relacionados com a técnica de angioplastia não tiveram importância na gênese dos NF. Na PWI foi observada melhora nos parâmetros temporais TTP (p<0,001) e MTT (p=0,019) quando comparados de forma normalizada em relação ao território contralateral. CONCLUSÃO: Os novos focos de restrição na DWI após ACS (NF) foram mais comuns no território ipsilateral (77,19%), no entanto houve NF no território contralateral à ACS (22,81%), possivelmente, associados ao cateterismo diagnóstico. Os NF, na sua maioria, são de pequeno diâmetro (<10 mm em 91,53%). Melhora precoce na PWI, observada nos dados normalizados, foi demonstrada nos parâmetros temporais (TTP e MTT). / INTRODUCTION: Carotid angioplasty with stent (CAS) under cerebral protection is a therapeutic option in patients with carotid stenosis. There is a risk of embolism even with a filter, and changes in cerebral perfusion after treatment are not clearly understood. The purpose of this study was to evaluate changes in diffusion- (DWI) and perfusion- (PWI) weighted magnetic resonance imaging (MRI) sequences correlating them with the technical aspects of CAS, stenosis characteristics and patient demographic data. METHODS: Thirty-six carotid stenosis patients with an mean age of 72.08 years were submitted to MRI exam one day before and up to 72 hours after CAS with filter protection. All patients were asymptomatic after CAS. Areas of restriction on DWI were correlated to demographic aspects, technique of angioplasty as well the presence of previous stroke by MRI. The parameters, CBV - cerebral blood volume; MTT - mean transit time, and TTP- time to peak, are used for PWI analysis. RESULTS: Eighteen of the 36 patients (50.00%) presented new focus (NF) of restriction by DWI after CAS. All new focus were clinically silent. The NF were located in the cerebral area fed by the carotid artery submitted to CAS in 77.19% and smaller than 10mm in 91.53%. NF in cerebral area not irrigated by carotid artery submitted by angioplasty correspond to 22,81 %. The presence of previous ischemic lesion on MRI was the only factor which influenced the appearance of NF (p=0.037). Demographic factors and aspects related to angioplasty technique had no importance on NF genesis. Improvement in PWI timing parameters - TTP (p<0.001) and MTT (p=0.019) were observed in relation to the contralateral territory (normalized data). CONCLUSION: The restriction NF in the DWI after CAS are more common in the ipsilateral territory (77.19%), however there were some NF in the contralateral territory to the CAS (22.81%), possibly associated with diagnostic catheterization. Most of the NF were small in diameter (<10mm in 91.53%). Short-term improvement in PWI were demonstrated by normalized timing parameters (TTP and MTT).
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Der Einfluss von Plaquemorphologie und anderen prädiktiven Faktoren auf das Auftreten von Mikroembolien während der Stentgeschützten Perkutanen Angioplastie der Karotiden (SPAC) / The influence of plaque morphology and other predictive factors on microembolic lesions during stent-protected angioplasty of the carotids (SPAC)Weber, Peter 27 April 2010 (has links)
No description available.
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