A complexidade dos sistemas integrados em chips bem como a arquitetura de processadores comerciais vem crescendo dramaticamente nos últimos anos. Com isto, a dificuldade de avaliarmos a suscetibilidade às falhas em decorrência da incidência de partículas espaciais carregadas nestes dispositivos cresce com a mesma taxa. Este trabalho apresenta uma análise comparativa da susceptibilidade à erros de software em um microprocessador embarcado ARM Cortex-A9 single core de larga escala comercial, amplamente utilizado em aplicações críticas, executando um conjunto de 11 aplicações desenvolvidas para um ambiente bare metal e para o sistema operacional Linux. A análise de soft errors é executada por injeção de falhas na plataforma de simulação OVPSim juntamente com o injetor OVPSim-FIM, capaz de sortear o momento e local de injeção de uma falha. A campanha de injeção de falhas reproduz milhares de bit-flips no banco de registradores do microprocessador durante a execução do conjunto de benchmarks que possuem um comportamento de código diverso, desde dependência de fluxo de controle até aplicações intensivas em dados. O método de análise consiste em comparar execuções da aplicação onde falhas foram injetadas com uma execução livre de falhas. Os resultados apresentam a taxa de falhas que são classificadas em: mascaradas (UNACE), travamento ou perda de controle de fluxo (HANG) e erro nos resultados (SDC). Adicionalmente, os erros são classificados por registradores, separando erros latentes por sua localização nos resultados e por exceções detectadas pelo sistema operacional, provendo novas possibilidades de análise para um processador desta escala. O método proposto e os resultados obtidos podem ajudar a orientar desenvolvedores de software na escolha de diferentes arquiteturas de código, a fim de aprimorar a tolerância à falhas do sistema embarcado como um todo. / The complexity of integrated system on-chips as well as commercial processor’s architecture has increased dramatically in recent years. Thus, the effort for assessing the susceptibility to faults due to the incidence of spatial charged particles in these devices has growth at the same rate. This work presents a comparative analysis of soft errors susceptibility in the commercial large-scale embedded microprocessor ARM Cortex-A9 single core, widely used in critical applications, performing a set of 11 applications developed for a bare metal environment and the Linux operating system. The soft errors analysis is performed by fault injection in OVPSim simulation platform along with the OVPSim-FIM fault injector, able to randomly select the time and place to inject the fault. The fault injection campaign reproduces thousands of bit-flips in the microprocessor register file during the execution of the benchmarks set, with a diverse code behavior ranging from control flow dependency to data intensive applications. The analysis method is based on comparing applications executions where faults were injected with a fault-free implementation. The results show the error rate classified by their effect as: masked (UNACE), crash or loss of control flow (HANG) and silent data corruption (SDC); and by register locations. By separating latent errors by its location in the results and exceptions detected by the operating system, one can provide new better observability for a large-scale processor. The proposed method and the results can guide software developers in choosing different code architectures in order to improve the fault tolerance of the embedded system as a whole.

A complexidade dos sistemas integrados em chips bem como a arquitetura de processadores comerciais vem crescendo dramaticamente nos últimos anos. Com isto, a dificuldade de avaliarmos a suscetibilidade às falhas em decorrência da incidência de partículas espaciais carregadas nestes dispositivos cresce com a mesma taxa. Este trabalho apresenta uma análise comparativa da susceptibilidade à erros de software em um microprocessador embarcado ARM Cortex-A9 single core de larga escala comercial, amplamente utilizado em aplicações críticas, executando um conjunto de 11 aplicações desenvolvidas para um ambiente bare metal e para o sistema operacional Linux. A análise de soft errors é executada por injeção de falhas na plataforma de simulação OVPSim juntamente com o injetor OVPSim-FIM, capaz de sortear o momento e local de injeção de uma falha. A campanha de injeção de falhas reproduz milhares de bit-flips no banco de registradores do microprocessador durante a execução do conjunto de benchmarks que possuem um comportamento de código diverso, desde dependência de fluxo de controle até aplicações intensivas em dados. O método de análise consiste em comparar execuções da aplicação onde falhas foram injetadas com uma execução livre de falhas. Os resultados apresentam a taxa de falhas que são classificadas em: mascaradas (UNACE), travamento ou perda de controle de fluxo (HANG) e erro nos resultados (SDC). Adicionalmente, os erros são classificados por registradores, separando erros latentes por sua localização nos resultados e por exceções detectadas pelo sistema operacional, provendo novas possibilidades de análise para um processador desta escala. O método proposto e os resultados obtidos podem ajudar a orientar desenvolvedores de software na escolha de diferentes arquiteturas de código, a fim de aprimorar a tolerância à falhas do sistema embarcado como um todo. / The complexity of integrated system on-chips as well as commercial processor’s architecture has increased dramatically in recent years. Thus, the effort for assessing the susceptibility to faults due to the incidence of spatial charged particles in these devices has growth at the same rate. This work presents a comparative analysis of soft errors susceptibility in the commercial large-scale embedded microprocessor ARM Cortex-A9 single core, widely used in critical applications, performing a set of 11 applications developed for a bare metal environment and the Linux operating system. The soft errors analysis is performed by fault injection in OVPSim simulation platform along with the OVPSim-FIM fault injector, able to randomly select the time and place to inject the fault. The fault injection campaign reproduces thousands of bit-flips in the microprocessor register file during the execution of the benchmarks set, with a diverse code behavior ranging from control flow dependency to data intensive applications. The analysis method is based on comparing applications executions where faults were injected with a fault-free implementation. The results show the error rate classified by their effect as: masked (UNACE), crash or loss of control flow (HANG) and silent data corruption (SDC); and by register locations. By separating latent errors by its location in the results and exceptions detected by the operating system, one can provide new better observability for a large-scale processor. The proposed method and the results can guide software developers in choosing different code architectures in order to improve the fault tolerance of the embedded system as a whole.

Fundamentos: O implante de stents coronários constitui-se na técnica mais prevalente de revascularização percutânea, em especial pela prevenção da reestenose, quando comparado às intervenções com o balão. No entanto, a reestenose intra-stent, que ocorre em cerca de 25% dos casos, restringe os seus benefícios clínicos e econômicos tardios. Demonstrou-se que a hiperplasia neo-intimal decorrente da reação da parede vascular causada pelo implante do stent, é responsável pelas recidivas. Interroga-se se um protocolo de medicamentos contemplando doses máximas de manutenção de clopidogrel e atorvastatina poderia reduzir a hiperplasia neo-intimal e a reestenose. Objetivos: O objetivo primário foi aferir se esta associação de medicamentos reduziria o volume de hiperplasia neo-intimal (35% ou mais), expressa pela obstrução volumétrica da luz, mensurada pelo ultrassom intracoronário, 12 meses após a intervenção. Os objetivos secundários foram: os resultados da angiografia quantitativa e os eventos cardíacos adversos maiores (óbito, infarto e revascularização do vaso-alvo). Casuística e métodos: Foram incluídos casos eletivos e com lesões primárias nas artérias naturais. Os pacientes foram tratados com stents não farmacológicos e randomizados em dois grupos: A, com 50 pacientes medicados com doses máximas de clopidogrel e atorvastatina; e grupo B com 50 casos, medicados com 75mg de clopidogrel e doses de sinvastatina rotineiramente prescritas para obtenção das metas recomendadas para controle lipídico. Resultados: Ambos os grupos não apresentaram diferenças significantes em relação às características clínicas, angiográficas e técnicas, com exceção do diabetes, mais comum em A (36% vs 16%; p=0,02). Aos 12 meses de evolução, observaram-se eventos cardíacos maiores (12% versus 18%; p = 0,56) e revascularização do vaso-alvo (4% versus 2%; p>0,99) sem diferença significante. Nova angiografia coronária foi obtida em 98% dos casos dos dois grupos, observando-se taxa de reestenose de 8,1% e 8,2% nos grupos A e B (p>0,99). A perda tardia da luz arterial foi semelhante [0,9 mm (DP 0,5 mm) versus 1,1 mm (DP 0,7 mm); p = 0,22], o mesmo acontecendo com o diâmetro mínimo da luz [2,2 mm (DP 0,6 mm) versus 1,9 mm (DP 0,6 mm); p = 0,12]. Realizou-se ultrassom intracoronário em 98% dos pacientes de ambos os grupos, observando-se obstrução do volume da luz de 36,3% (DP 10,3%) no grupo A e de 40,1% (DP 10,9%) no grupo B (p = 0,14). Conclusões: Os resultados deste estudo demonstram que: 1) a terapêutica adjunta utilizando doses máximas de clopidogrel 150 mg/dia e atorvastatina 80 mg/dia não reduz o volume de hiperplasia neo-intimal, expressa pela obstrução volumétrica da luz; 2) as variáveis da angiografia quantitativa e os eventos cardíacos adversos maiores não mostraram diferenças significativas entre os dois grupos. / Coronary stent implantation is the current technique of choice in patients undergoing percutaneous intervention. They effectively reduce acute occlusion and restenosis even in complex lesions. However, instent restenosis occurs in up to 25% of the treated cases and there are several theories elaborating the possible relation between coronary artery thrombosis and inflammation to neointimal proliferation and the mechanism of obstruction recurrence. There are questions whether an optimized medical treatment based on maximum doses of Clopidogrel and Atorvastatin could limit neointimal hyperplasia and restenosis. Objectives: Primary endpoint was to assess the efficacy of this scheme in reducing neointimal hyperplasia volume (XX% or more), according to intravascular ultrasound measurements, 12 months after the index intervention. Secondary endpoints were quantitative angiography measurements and major adverse cardiac events (death, myocardial infarction and target vessel revascularization). Methods: We included patients with de novo lesions undergoing elective implantation of uncoated stents. Patients were divided according to the drug regimen into Group A - 50 patients receiving maximal atorvastatin and clopidogrel doses; and Group B - 50 cases treated with standard clopidogrel and simvastatin doses. Results: Groups were similar concerning clinical and angiographic characteristics, except for diabetes, more frequent in Group A (36% vs 16%, p = 0.02). At the end of 12 months major cardiac events (12% versus 18%, p = 0.56) and target vessel revascularization (4% versus 2%, p> 0.99) did not show differences between groups. Coronary angiography was obtained in 98% of the cases and the restenosis rate was 8.1% (A group) and 8,2% (B group) (p> 0.99). Late luminal loss was similar [0.9 mm (SD 0.5 mm) versus 1.1 mm (SD 0.7 mm), p = 0.22], as well as the minimum lumen diameter [2.2 mm (SD 0.6 mm) versus 1.9 mm (SD 0.6 mm), p = 0.12]. IVUS was done in 98% of patients in both groups, and the volume of neointimal hyperplasia was not significantly different in both groups [61.8 mm 3 (SD 35.4 mm3) mm3 versus 66.3 (SD 31.6 mm3), p = 0.58]. Luminal volume obstruction was 36.3% (SD 10.3%) in group A and 40.1% (SD 10.9%) in group B (p = 0.14). Conclusions: According to our results we may conclude that: 1) the therapeutic regimen using maximum doses of atorvastatin and clopidogrel did not reduce the volume of neointimal hyperplasia, 2) restenosis rate, quantitative angiography results and the rate of major adverse cardiac events were not affected by the treatment regimen.

Σκοπός: Η μελέτη είχε ως σκοπό την διερεύνηση της ασφάλειας και της αποτελεσματικότητας των sirolimus-eluting stent, σε σχέση με τα απλά μεταλλικά stent, στα πλαίσια αγγειοπλαστικής των κνημιαίων αγγείων, σε ασθενείς με χρόνια κρίσιμη ισχαιμία του κάτω άκρου. Πρόκειται για μια προοπτική ελεγχόμενη, κλινική μελέτη με διπλό σκέλος. Τα stent τοποθετήθηκαν σε περιπτώσεις μη ικανοποιητικής αγγειοπλαστικής (δηλ. σε περιπτώσεις ελαστικής επαναφοράς-υπολειμματικής στένωσης >30% και σε περιπτώσεις διαχωρισμού). Οι ασθενείς ελέγχθηκαν κλινικά και αγγειογραφικά στο εξάμηνο και στο 1 έτος. Ασθενείς και μέθοδοι: 29 ασθενείς, εκ των οποίων 8 γυναίκες και 21 άνδρες, με μέση ηλικία τα 68,7 έτη υποβλήθηκαν σε αγγειοπλαστική στα κνημιαία αγγεία, με απλά μεταλλικά stent, ομάδα Β. Σε αυτή την ομάδα τοποθετήθηκαν απλά stent σε 65 αλλοιώσεις, εκ των οποίων 38 στενώσεις και 27 αποφράξεις σε συνολικά 40 κνημιαία αγγεία. Άλλοι 29 ασθενείς, 8 γυναίκες και 21 άνδρες, με μέση ηλικία τα 68,8 έτη αντιμετωπίστηκαν με sirolimus-eluting stent, ομάδα S. Σε αυτή την ομάδα αντιμετωπίστηκαν 66 αλλοιώσεις εκ των οποίων 46 στενώσεις και 20 αποφράξεις, σε 41 συνολικά αγγεία. Οι ασθενείς επανελέγχθηκαν κλινικά και με ενδαρτηριακή αγγειογραφία στους 6 μήνες και στο 1 έτος, μετά την αρχική επέμβαση. Έγινε στατιστική ανάλυση των αποτελεσμάτων. Αποτελέσματα: Οι συνοδές νόσοι ήταν περισσότερες στην ομάδα S (όπως η συμπτωματική νόσος από την καρδιά και τις καρωτίδες, καθώς και η υπερλιπιδαιμία, p<0.05). Η τεχνική επιτυχία ήταν 96,6% (28/29 άκρα) στην ομάδα Β έναντι 100% (29/29 άκρα) στην ομάδα S (p=0.16) Στον επανέλεγχο εξαμήνου: Η βατότητα ήταν 68,1% στην ομάδα Β και 92,0% στην ομάδα S, (p<0.002). Τα μεγαλύτερα ποσοστά βατότητας των sirolimus-eluting stent, μετά από πολυπαραγοντική regression analysis είχαν OR 5.625, με 95% CI 1.711- 18.493, που ήταν στατιστικά σημαντικό (p=0.004). Η δυαδική επαναστένωση εντός του stent ήταν 55,3% ενώ η επαναστένωση στα άκρα του stent ήταν 66,0% στους ασθενείς με τα απλά μεταλλικά stent. Αντιθέτως τα ποσοστά στους ασθενείς με sirolimus-eluting stent ήταν 4,0% και 32,0% αντίστοιχα. Συγκεκριμένα η επαναστένωση εντός του stent είχε OR 0.067, με 95% CI 0.021-0.017, και η επαναστένωση στα άκρα του stent είχε OR 0.229 με 95% CI 0.099-0.533. Και τα δύο ήταν ήταν στατιστικά σημαντικά με p<0.001 και p=0.001, αντίστοιχα. Τα συνολικά ποσοστά επανεπέμβασης (TLR) στο εξάμηνο ήταν 17,0% στην ομάδα Β έναντι 4,0% στην ομάδα S, (OR 0.057, με 95% CI 0.008-0.426). Το αποτέλεσμα ήταν επίσης στατιστικά σημαντικό υπέρ των sirolimus stent. (p=0.02) Η διάσωση του άκρου ήταν 100% και στις δύο ομάδες. Η θνησιμότητα και ο ελάσσων ακρωτηριασμός στο εξάμηνο ήταν 6,9% και 17,2% στην ομάδα Β έναντι 10,3% και 3,4% στην ομάδα S (p=0.32 και p=0.04, αντίστοιχα). Στον επανέλεγχο έτους: Τα sirolimus-eluting stent σχετίζoνταν και πάλι με καλύτερη πρωτογενή βατότητα (OR 10.401, με 95% CI 3.425-31.589, p<0.001) και σημαντικά μειωμένη δυαδική επαναστένωση εντός του stent (OR 0.156, με 95% CI 0.060-0.407, p<0.001), καθώς και στα άκρα του stent. (OR 0.089, με 95% CI 0.023-0.349, p=0.001) Τα ποσοστά επανεπέμβασης στις βλάβες (TLR) ήταν πολύ μικρότερα στην ομάδα του sirolimus (OR 0.238, με 95% CI 0.067-0.841, p=0.026) . Δεν υπήρξαν στατιστικά σημαντικές διαφορές ανάμεσα στις δύο ομάδες Β και S όσον αφορά στα ποσοστά θνησιμότητας 10,3% έναντι 13,8%, στη διάσωση του άκρου 100% έναντι 96% και στους ελάσσονες ακρωτηριασμούς 17,2% έναντι 10,3% αντίστοιχα. Συμπεράσματα: Τα sirolimus-eluting stents περιορίζουν την ενδοθηλιακή υπερπλασία στα κνημιαία αγγεία. Η εφαρμογή τους έχει ως αποτέλεσμα την σημαντική μείωση των ποσοστών επαναστένωσης και μειώνει την ανάγκη για επανεπεμβάσεις. / Aim : The purpose of our study was to investigate the 6-month and 1-year angiographic and clinical outcome in the setting of a controlled clinical study. The study examined the safety and relative effectiveness of sirolimus-eluting stents opposed to conventional metal stents, in the infrapopliteal vessels, in patients with critical limb ischemia (CLI). The stents were used in a bail-out setting during infrapopliteal endovascular procedures, i. e. stenting was carried out in cases of suboptimal angioplasty results (recoil - residual stenosis >30%, or in cases of dissection, after angioplasty). Patients and Methods: Twenty-nine patients comprising 8 women and 21 men with a mean age of 68.7 years were submitted to infrapopliteal revascularization with conventional (bare) metal stents, called group B. In these patients 65 lesions were treated with bare stents, of whom 38 stenoses and 27 occlusions, in a total of 40 infrapopliteal vessels. Another 29 patients, again 8 women and 21 men, with a mean age of 68.8 years were treated with sirolimus-eluting stents, named group S. There were 66 lesions in this group with 46 of them stenoses and 20 occlusions, in a total of 41 arteries. Patients were followed-up with clinical examination and intrarterial angiography 6 months and 1 year after the procedure. Both results were subsequently analyzed statistically. 135 Results: Co morbidities like symptomatic cardiac and carotid disease, as well as hyperlipidemia were more prominent in group S (p<0.05). Technical success was 96.6% (28/29 limbs) in group B against 100.0% (29/29 limbs) in group S (p=0.16). During 6-month patient follow-up: Primary patency was 68.1% in group B opposed to 92.0% in group S (p<0.002). Sirolimus-eluting stents exhibited higher primary patency with OR 5.625 and 95% CI 1.711-18.493, which was statistically significant (p=0.004). Binary in-stent restenosis rate was 55.3% while in-segment restenosis was 66.0%, in patients who had received bare metal stents. In opposition the respective restenosis rates, in patients with sirolimus-eluting stents were 4.0% and 32.0%. Diminished in-stent (OR 0.067 with 95% CI 0.021-0.017) and insegment (OR 0.229 with 95% CI 0.099-0.533) binary restenosis were both statistically significant with p values being p<0.001 and p=0.001 respectively. Collective target lesion re-intervention (TLR) at 6 month follow-up was 17.0% in group B against 4.0% (OR 0.057 with 95% CI 0.008-0.426) in group S, which proved again statistically significant for sirolimus stents (p=0.02). Six-month limb salvage rate was 100% in both groups. Six-month mortality and minor amputation rates were respectively 6.9% and 17.2%, in group B versus 10.3% and 3.4%, in group S (p=0.32 and p=0.04, respectively). During 1-year patient follow-up: 136 SES were still related with better primary patency rate (OR 10.401 with 95% CI 3.425-31.589, p<0.001) and considerably lesser events of in-stent binary restenosis (OR 0.156, 95% CI 0.060-0.407, p<0.001) as well as insegment (OR 0.089, 95% CI 0.023-0.349, p=0.001) binary restenosis. Target lesion re-intervention (TLR), was much lower in the SES patients group during 1-year follow-up (OR 0.238 with 95% CI 0.067-0.841, p=0.026) . At 1 year follow-up there were no statistically significant differences among group B and group S regarding mortality (10.3% against 13.8%), limb salvage rates (100% vs. 96%) and minor amputation (17.2% vs. 10.3%). Conclusions: Sirolimus-eluting stents appear to limit intimal hyperplasia in the infrapopliteal vessels. The use of sirolimus-eluting stents decreases considerably restenosis rates in the infrapopliteal vessels and reduces the need for repeat interventions

Fundamentos: O implante de stents coronários constitui-se na técnica mais prevalente de revascularização percutânea, em especial pela prevenção da reestenose, quando comparado às intervenções com o balão. No entanto, a reestenose intra-stent, que ocorre em cerca de 25% dos casos, restringe os seus benefícios clínicos e econômicos tardios. Demonstrou-se que a hiperplasia neo-intimal decorrente da reação da parede vascular causada pelo implante do stent, é responsável pelas recidivas. Interroga-se se um protocolo de medicamentos contemplando doses máximas de manutenção de clopidogrel e atorvastatina poderia reduzir a hiperplasia neo-intimal e a reestenose. Objetivos: O objetivo primário foi aferir se esta associação de medicamentos reduziria o volume de hiperplasia neo-intimal (35% ou mais), expressa pela obstrução volumétrica da luz, mensurada pelo ultrassom intracoronário, 12 meses após a intervenção. Os objetivos secundários foram: os resultados da angiografia quantitativa e os eventos cardíacos adversos maiores (óbito, infarto e revascularização do vaso-alvo). Casuística e métodos: Foram incluídos casos eletivos e com lesões primárias nas artérias naturais. Os pacientes foram tratados com stents não farmacológicos e randomizados em dois grupos: A, com 50 pacientes medicados com doses máximas de clopidogrel e atorvastatina; e grupo B com 50 casos, medicados com 75mg de clopidogrel e doses de sinvastatina rotineiramente prescritas para obtenção das metas recomendadas para controle lipídico. Resultados: Ambos os grupos não apresentaram diferenças significantes em relação às características clínicas, angiográficas e técnicas, com exceção do diabetes, mais comum em A (36% vs 16%; p=0,02). Aos 12 meses de evolução, observaram-se eventos cardíacos maiores (12% versus 18%; p = 0,56) e revascularização do vaso-alvo (4% versus 2%; p>0,99) sem diferença significante. Nova angiografia coronária foi obtida em 98% dos casos dos dois grupos, observando-se taxa de reestenose de 8,1% e 8,2% nos grupos A e B (p>0,99). A perda tardia da luz arterial foi semelhante [0,9 mm (DP 0,5 mm) versus 1,1 mm (DP 0,7 mm); p = 0,22], o mesmo acontecendo com o diâmetro mínimo da luz [2,2 mm (DP 0,6 mm) versus 1,9 mm (DP 0,6 mm); p = 0,12]. Realizou-se ultrassom intracoronário em 98% dos pacientes de ambos os grupos, observando-se obstrução do volume da luz de 36,3% (DP 10,3%) no grupo A e de 40,1% (DP 10,9%) no grupo B (p = 0,14). Conclusões: Os resultados deste estudo demonstram que: 1) a terapêutica adjunta utilizando doses máximas de clopidogrel 150 mg/dia e atorvastatina 80 mg/dia não reduz o volume de hiperplasia neo-intimal, expressa pela obstrução volumétrica da luz; 2) as variáveis da angiografia quantitativa e os eventos cardíacos adversos maiores não mostraram diferenças significativas entre os dois grupos. / Coronary stent implantation is the current technique of choice in patients undergoing percutaneous intervention. They effectively reduce acute occlusion and restenosis even in complex lesions. However, instent restenosis occurs in up to 25% of the treated cases and there are several theories elaborating the possible relation between coronary artery thrombosis and inflammation to neointimal proliferation and the mechanism of obstruction recurrence. There are questions whether an optimized medical treatment based on maximum doses of Clopidogrel and Atorvastatin could limit neointimal hyperplasia and restenosis. Objectives: Primary endpoint was to assess the efficacy of this scheme in reducing neointimal hyperplasia volume (XX% or more), according to intravascular ultrasound measurements, 12 months after the index intervention. Secondary endpoints were quantitative angiography measurements and major adverse cardiac events (death, myocardial infarction and target vessel revascularization). Methods: We included patients with de novo lesions undergoing elective implantation of uncoated stents. Patients were divided according to the drug regimen into Group A - 50 patients receiving maximal atorvastatin and clopidogrel doses; and Group B - 50 cases treated with standard clopidogrel and simvastatin doses. Results: Groups were similar concerning clinical and angiographic characteristics, except for diabetes, more frequent in Group A (36% vs 16%, p = 0.02). At the end of 12 months major cardiac events (12% versus 18%, p = 0.56) and target vessel revascularization (4% versus 2%, p> 0.99) did not show differences between groups. Coronary angiography was obtained in 98% of the cases and the restenosis rate was 8.1% (A group) and 8,2% (B group) (p> 0.99). Late luminal loss was similar [0.9 mm (SD 0.5 mm) versus 1.1 mm (SD 0.7 mm), p = 0.22], as well as the minimum lumen diameter [2.2 mm (SD 0.6 mm) versus 1.9 mm (SD 0.6 mm), p = 0.12]. IVUS was done in 98% of patients in both groups, and the volume of neointimal hyperplasia was not significantly different in both groups [61.8 mm 3 (SD 35.4 mm3) mm3 versus 66.3 (SD 31.6 mm3), p = 0.58]. Luminal volume obstruction was 36.3% (SD 10.3%) in group A and 40.1% (SD 10.9%) in group B (p = 0.14). Conclusions: According to our results we may conclude that: 1) the therapeutic regimen using maximum doses of atorvastatin and clopidogrel did not reduce the volume of neointimal hyperplasia, 2) restenosis rate, quantitative angiography results and the rate of major adverse cardiac events were not affected by the treatment regimen.

Cloud computing allows on-demand provision, configuration and assignment of computing resources with minimum cost and effort for users and administrators. Managing the physical infrastructure that underlies cloud computing services relies on the need to provision and manage bare-metal computer hardware. Hence there is a need for quick loading of operating systems in bare-metal and virtual machines to service the demands of users. The focus of the study is on developing a technique to load these machines remotely, which is complicated by the fact that the machines can be present in different Ethernet broadcast domains, physically distant from the provisioning server. The use of available bare-metal provisioning frameworks require significant skills and time. Moreover, there is no easily implementable standard method of booting across separate and different Ethernet broadcast domains. This study proposes a new framework to provision bare-metal hardware remotely using layer 2 services in a secure manner. This framework is a composition of existing tools that can be assembled to build the framework.

Coronary artery disease (CAD) affects every fifth person in the world. The gold-standard treatment for CAD is stent implantation, however, the existing therapy is not sufficient due to many reasons. For instance, in-stent restenosis, biocompatibility, controlled degradation rate, protein adsorption, and adequate endothelialization are still the main concerns. In the last two decades, the field of stent technology has been grown rapidly and many new stent types and in vitro testing methods for stent characterization have been developed to minimize the aforementioned issues. In this vicinity, there are still many unaddressed issues: i) the quantitative analysis of corrosion is conducted with simpler samples made of stent material instead of stents, in most cases due to the absence of a mathematical model to calculate the entire stent surface area (ESSA); ii) in vitro stent testing in environments that are very far from actual physiological environments; iii) Evaluation of the influence of in-vitro test conditions on coated metallic stents; iv) absence of flow-induced shear stress (FISS) corrosion model, to mention a few. This thesis presents the novel ESSA model, the fluid dynamic experimental setup with the integration of various sensors and pH control, the influence of in vitro degradation behavior of the titanium oxynitride (TiOxNy) coated stainless steel stents and anodized AZ31 samples, and the FISS corrosion model. The results show some important contributions in this field, however, there is still a huge potential for the development of promising stent characterization solutions. / Die koronare Herzkrankheit (KHK) betrifft jeden fünften Menschen auf der Welt. Der Goldstandard bei der Behandlung von KHK ist die Stent-Implantation, doch die bestehende Therapie ist aus vielen Gründen nicht ausreichend. So sind beispielsweise die Restenose im Stent, die Biokompatibilität, die kontrollierte Abbaugeschwindigkeit, die Proteinadsorption und die angemessene Endothelialisierung nach wie vor die Hauptprobleme. In den letzten zwei Jahrzehnten hat sich die Stenttechnologie rasant weiterentwickelt, und es wurden viele neue Stenttypen und In-vitro-Testmethoden zur Stentcharakterisierung entwickelt, um die oben genannten Probleme zu minimieren. In dieser Umgebung gibt es noch viele ungelöste Probleme: i) die quantitative Analyse der Korrosion wird mit einfacheren Proben aus Stentmaterial anstelle von Stents durchgeführt, in den meisten Fällen aufgrund des Fehlens eines mathematischen Modells zur Berechnung der gesamten Stentoberfläche (ESSA); ii) In-vitro-Stent-Tests in Umgebungen, die sehr weit von der tatsächlichen physiologischen Umgebung entfernt sind; iii) Bewertung des Einflusses von In-vitro-Testbedingungen auf beschichtete metallische Stents; iv) Fehlen eines FISS-Korrosionsmodells (flow-induced shear stress), um nur einige zu nennen. In dieser Arbeit werden das neuartige ESSA-Modell, der strömungsdynamische Versuchsaufbau mit der Integration verschiedener Sensoren und pH-Kontrolle, der Einfluss des In-vitro-Degradationsverhaltens der mit Titanoxynitrid (TiOxNy) beschichteten Edelstahlstents und anodisierten AZ31-Proben sowie das FISS-Korrosionsmodell vorgestellt. Die Ergebnisse zeigen einige wichtige Beiträge in diesem Bereich, jedoch gibt es noch ein großes Potenzial für die Entwicklung von vielversprechenden Lösungen zur Charakterisierung von Stents.