Ethernet-based systems: contributions to the holistic analysis

A number of characteristics are boosting the eagerness of extending Ethernet to also cover factory-floor distributed real-time applications. Full-duplex links, non-blocking and priority-based switching, bandwidth availability, just to mention a few, are characteristics upon which that eagerness is building up. But, will Ethernet technologies really manage to replace traditional Fieldbus networks? To this question, Fieldbus fundamentalists often argue that the two technologies are not comparable. In fact, Ethernet technology, by itself, does not include features above the lower layers of the OSI communication model. Where are the higher layers that permit building real industrial applications? And, taking for free that they are available, what is the impact of those protocols, mechanisms and application models on the overall performance of Ethernetbased distributed factory-floor applications? In this paper we provide some contributions that may pave the way towards providing some reasonable answers to these issues.

From simulation to statistical analysis: timeliness assessment of ethernet/IP-based distributed systems

A number of characteristics are boosting the eagerness of extending Ethernet to also cover factory-floor distributed real-time applications. Full-duplex links, non-blocking and priority-based switching, bandwidth availability, just to mention a few, are characteristics upon which that eagerness is building up. But, will Ethernet technologies really manage to replace traditional Fieldbus networks? Ethernet technology, by itself, does not include features above the lower layers of the OSI communication model. In the past few years, it is particularly significant the considerable amount of work that has been devoted to the timing analysis of Ethernet-based technologies. It happens, however, that the majority of those works are restricted to the analysis of sub-sets of the overall computing and communication system, thus without addressing timeliness at a holistic level. To this end, we are addressing a few inter-linked research topics with the purpose of setting a framework for the development of tools suitable to extract temporal properties of Commercial-Off-The-Shelf (COTS) Ethernet-based factory-floor distributed systems. This framework is being applied to a specific COTS technology, Ethernet/IP. In this paper, we reason about the modelling and simulation of Ethernet/IP-based systems, and on the use of statistical analysis techniques to provide usable results. Discrete event simulation models of a distributed system can be a powerful tool for the timeliness evaluation of the overall system, but particular care must be taken with the results provided by traditional statistical analysis techniques.

Ethernet goes real-time: a survey on research and technological developments

Ethernet is the most popular LAN technology. Its low price and robustness, resulting from its wide acceptance and deployment, has created an eagerness to expand its responsibilities to the factory-floor, where real-time requirements are to be fulfilled. However, it is difficult to build a real-time control network using Ethernet, because its MAC protocol, the 1-persistent CSMA/CD protocol with the BEB collision resolution algorithm, has unpredictable delay characteristics. Many anticipate that the recent technological advances in Ethernet such as the emerging Fast/Gigabit Ethernet, micro-segmentation and full-duplex operation using switches will also enable it to support time-critical applications. This technical report provides a comprehensive look at the unpredictability inherent to Ethernet and at recent technological advances towards real-time operation.

Tectónica da cadeia da Arrábida

Geociências, Museu Nac. Hist. Nat. Univ. Lisboa, nº 2, 35-84

Síndrome de Churg-Strauss, Aneurismas Femorais Venosos e Tromboembolismo Pulmonar

OBJECTIVE: Venous aneurysms of the lower limbs are rare. When they involve the deep venous system, they can be associated with deep venous thrombosis and pulmonary embolism. The authors report the case of a 63-year-old women evaluated by duplex imaging and venography, in the context of a pulmonary embolism, and detected bilateral large aneurysms of the femoral veins (5 cm in the right femoral vein and 4 cm in the left femoral vein). The aneurysms were located at the bifurcation of the common femoral vein with the superficial and profound veins. METHOD: The right aneurysm was partially thrombosed. The patient was asymptomatic in the lower-limb extremities. After a period of anticoagulation, the authors proceeded to surgically excise the right aneurysm and replaced the venous system using a polytetrafluoroethylene (PTFE) graft with the construction of an a-v fistula. RESULT: The patient had no complications in the postoperative period and her 8-month follow-up examination revealed no symptoms, not even leg edema. The duplex scan showed patency of the graft. She continued with oral anticoagulation. The histologic examination revealed an eosinophilic inflammatory reaction of the vein wall, compatible with the diagnosis of Churg-Strauss syndrome. CONCLUSION: The authors conclude that they have probably described the first case in the international literature of a venous aneurysm with a Churg-Strauss syndrome and pulmonary embolism.

The use of stents in the treatment of traumatic intimal flaps: case report

Treatment of arterial traumatic intimal lesions is controversial due to its unknown natural history. Current therapeutical options include arterial reconstruction and clinical observation. The idea of using stents to correct intimal flaps is based on their use to correct dissections, flaps, and arterial irregularities after angioplasty. We report the successful treatment of a traumatic intimal flap of the superficial femoral artery, caused by gunshot trauma, with a Palmaz stent in the acute period. One year after the operation, a duplex scan revealed normal flow in the artery and complete exclusion of the intimal flap; distal pulses were palpable, and the patient was completely asymptomatic.

Persistence of the embryonic lateral marginal vein: report of two cases

PURPOSE: Congenital venous malformations of the lower limbs represent a particular challenge for the vascular surgeon. Persistence of fetal veins is a rare malformation, and the most common is the persistence of the lateral marginal vein usually observed in patients with Klippel-Trenaunnay Syndrome. The persistence of this embryonic vein as an isolated venous malformation without the other characteristics of the Klippel-Trenaunnay Syndrome has not yet been reported. This paper describes two cases. METHODS: Two patients, a 17-year-old male patient and a 16-year-old female, have had since their birth a large venous trunk in the lateral aspect of the right leg and thigh. The limbs underwent duplex scanning and phlebography. The surgical removal of the lateral marginal vein was performed. RESULTS: Surgical treatment resulted in very good functional and aesthetic results. Follow-up at 26 months showed no evidence of varicose vein recurrence. CONCLUSIONS: To achieve good results, surgical intervention may be indicated in cases of orthopedic deformity, hemorrhage, symptomatic, and unaesthetic lesions.

Qualidade nutricional de três espécies de clorofícias cultivadas em laboratório

Três espécies de algas clorofíceas, Scenedesmus quadricauda (Brèbisson, 1835), Ankistrodesmus gracilis (Korsikov, 1953) e Pediastrum duplex (Meyen, 1829), foram cultivadas no laboratório, usando como meio de cultura adubo químico N:P:K na proporção 20:5:20, respectivamente. O valor nutricional das algas foi avaliado pela concentração de clorofila-a e pelo carbono orgânico. As três espécies algais apresentaram alto valor nutricional, particularmente Scenedesmus quadricauda, que apresentou a maior percentagem de carbono em relação ao peso seco (21%), sendo considerada como alimento adequado para os organismos filtradores.

A cost study of common surface finish systems for steel structures

This paper presents part of a study aimed at finding a suitable, yet cost-effective, surface finish for a steel structure subject to the car washing environment and corrosive chemicals. The initial, life cycle and average equivalent annual (AEAC) costs for surface finishing methods were calculated for a steel structure using the LCCC algorithm developed by American Galvanizers Association (AGA). The cost study consisted of 45 common surface finish systems including: hot-dip galvanization (HDG), metallization, acrylic, alkyd and epoxy as well as duplex coatings such as epoxy zinc and inorganic zinc (IOZ). The results show that initial, life cycle and AEAC costs for hot dip galvanization are the lowest among all the other methods, followed by coal tar epoxy painting. The annual average cost of HDG for this structure was estimated about €0.22/m2, while the other cost-effective alternatives were: IOZ, polyurea, epoxy waterborne and IOZ/epoxy duplex coating.

Mineralizações associadas a shear zone networking na vertente oriental da Serra de Arga (Minho, Portugal)

Dissertação de mestrado em Ordenamento e Valorização de Recursos Geológicos

Avaliação de aterosclerose em transplantados renais através de métodos não invasivos

FUNDAMENTO: A disfunção endotelial pode ser considerada um evento precoce da aterogênese. OBJETIVO: Avaliar a aterosclerose em transplantados renais através do escore de cálcio coronariano, do duplex scan das carótidas e da reatividade braquial através do ultra-som. MÉTODOS: Avaliamos trinta transplantados renais do sexo masculino com função renal estável, idade média de 41,3 anos. RESULTADOS: A detecção da carga aterosclerótica nesta população foi significativa quando utilizada a técnica da reatividade braquial (86,7%), menos freqüente baseando-se na presença de placa carotídea (33,3%) ou no escore de cálcio coronariano (20%). Placa carotídea foi considerada quando a espessura era superior a 12 mm. O escore de cálcio coronariano foi anormal quando acima de oitenta pela escala de Agatston, sendo observado em um percentual baixo (21,7%) dos pacientes, possivelmente porque a tomografia pode não ser o método ideal para detectar aterosclerose em doentes renais, por não distinguir calcificações intimais da camada média. O controle clínico adequado, a baixa faixa etária e fatores relacionados ao tempo de diálise pré-transplante ou ao efeito antiinflamatório das drogas pós-transplante podem retardar o aparecimento das calcificações. CONCLUSÃO: A avaliação da carga aterosclerótica através do duplex scan das carótidas (33,3%) e do escore de cálcio coronariano (20%) não foi freqüente, não havendo correlação com o elevado índice de detecção de disfunção endotelial observado com o exame da reatividade braquial (86,7%).

Preditores de mortalidade hospitalar em pacientes com embolia pulmonar estáveis hemodinamicamente

FUNDAMENTO: A embolia pulmonar apresenta alta mortalidade em pacientes com hipotensão arterial ou choque circulatório. Entretanto, em pacientes hemodinamicamente estáveis, a associação de algumas variáveis clínicas com a mortalidade ainda não está claramente estabelecida. OBJETIVOS: Derivar um modelo de estratificação do risco de mortalidade intra-hospitalar em pacientes com embolia pulmonar hemodinamicamente estáveis. MÉTODOS: Estudo de coorte multicêntrico prospectivo de 582 pacientes consecutivos que foram admitidos em unidades de emergência ou de terapia intensiva, com suspeita clínica de embolia pulmonar, e que tiveram o diagnóstico confirmado por meio de um ou mais dos seguintes exames: arteriografia pulmonar, angiotomografia computadorizada helicoidal, angioressonância magnética, ecodopplercardiograma, cintilografia pulmonar ou duplex-scan venoso. Os dados sobre características demográficas, comorbidades e manifestações clínicas foram coletados e incluídos em uma análise de regressão logística para compor o modelo de predição. RESULTADOS: A mortalidade global foi de 14,1%. Foram identificadas como variáveis independentes de risco de óbito: idade > 65 anos; repouso no leito > 72h; cor pulmonale crônico; taquicardia sinusal e taquipnéia. Após a estratificação por faixas de risco, observaram-se mortalidades de 5,4%, 17,8% e 31,3%, respectivamente nos subgrupos de baixo, moderado e alto riscos. O modelo mostrou sensibilidade de 65,5% e especificidade de 80%, com uma área sob a curva de 0,77. CONCLUSÃO: Em pacientes hemodinamicamente estáveis com embolia pulmonar, a idade > 65 anos, o repouso no leito > 72h, o cor pulmonale crônico, a taquicardia sinusal e a taquipnéia foram preditores independentes da mortalidade intra-hospitalar. Entretanto o modelo de predição necessita ser validado em outras populações para sua incorporação à prática clínica.

Índice de resistividade renal como preditor da revascularização renal para hipertensão renovascular

FUNDAMENTO: A estenose arterial renal (EAR) é uma causa potencialmente reversível de hipertensão arterial sistêmica (HAS) e nefropatia isquêmica. Apesar da revascularização bem sucedida, nem todos os pacientes (pt) apresentam melhora clínica e alguns podem piorar. OBJETIVO: O presente estudo se destina a avaliar o valor do índice de resistividade renal (IR) como preditor dos efeitos da revascularização renal. MÉTODOS: Entre janeiro de 1998 e fevereiro de 2001, 2.933 pacientes foram submetidos ao duplex ultrassom renal. 106 desses pacientes apresentaram EAR significativa e foram submetidos a angiografia e revascularização renal. A pressão arterial (PA) foi medida antes e depois da intervenção, em intervalos de até 2 anos e as medicações prescritas foram registradas. Antes da revascularização, o IR foi medido em 3 locais do rim, sendo obtida uma média dessas medições. RESULTADOS: Dos 106 pacientes, 81 tiveram IR<80 e 25 RI>80. A EAR foi corrigida somente por angioplastia (PTA) em 25 pts, PTA + stent em 56 pts e cirurgicamente em 25 pts. Dos pacientes que se beneficiaram da revascularização renal; 57 dos 81 pacientes com IR <80 apresentaram melhora em comparação a 5 de 25 com IR > 80. Usando um modelo de regressão logística múltipla, o IR esteve significativamente associado à evolução da PA (p = 0,001), ajustado de acordo com os efeitos da idade, sexo, PAS, PAD, duração da hipertensão, o tipo de revascularização, número de fármacos em uso, nível de creatinina, presença de diabete melito, hipercolesterolemia, volume sistólico, doença arterial periférica e coronariana e tamanho renal (OR 99,6-95%CI para OR 6,1-1.621,2). CONCLUSÃO: A resistividade intrarrenal arterial, medida por duplex ultrassom, desempenha um papel importante na predição dos efeitos pós revascularização renal para EAR.

Relay-assisted transmission and radio resource management for wireless networks

The following paper presents an overview of the Ph.D Thesis1 presented in [1], which compiles all the research done during the period of time between 2004-2007. In that dissertation the relay-assisted transmission with half-duplex relays is analyzed from different points of view. This study is motivated by the necessity of finding innovative solutions to cope with the requirements of next generation wireless services, and with current radio technology. The use of relayed communications represents a change of paradigm of conventional communications, and requires the definition and evaluation of protocols to be applied to single or multiple-user relay communication. With the two fold goal of enhancing spectral efficiency and homogenize service in cellular communications, system design is investigated at physical (type of transmissions of the relay, decoding mode, ..) and upper layers (resource allocation, dynamic link control).

Solid-phase synthesis and NMR studies of modified oligonucleotides forming triplex helix and of oligonucleopeptides mimicking the topoisomerase I-DNA covalent complex

Report for the scientific sojourn carried out at the Institut de Biologia Molecular de Barcelona of the CSIC –state agency – from april until september 2007. Topoisomerase I is an essential nuclear enzyme that modulates the topological status of DNA, facilitating DNA helix unwinding during replication and transcription. We have prepared the oligonucleotide-peptide conjugate Ac-NLeu-Asn-Tyr(p-3’TTCAGAAGC5’)-LeuC-CONH-(CH2)6-OH as model compound for NMR studies of the Topoisomerase I- DNA complex. Special attention was made on the synthetic aspects for the preparation of this challenging compound especially solid supports and protecting groups. The desired peptide was obtained although we did not achieve the amount of the conjugate needed for NMR studies. Most probably the low yield is due to the intrinsic sensitive to hydrolysis of the phosphate bond between oligonucleotide and tyrosine. We have started the synthesis and the structural characterization of oligonucleotides carrying intercalating compounds. At the present state we have obtained model duplex and quadruplex sequences modified with acridine and NMR studies are underway. In addition to this project we have successfully resolved the structure of a fusion peptide derived from hepatitis C virus envelope synthesized by the group of Dr. Haro and we have synthesized and started the characterization of a modified G-quadruplex.