A Comparative Evaluation of Designs for Reliable Memory Systems

This paper addresses the design of storage systems for operation under critical environmental conditions. For these applications, these systems should have low latency time in access, high performance in throughput and high storage capabilities; therefore, they must be assembled using highly reliable components, while allowing flexibility in design. Commercial Off The Shelf (COTS) components have often been used. A COTS-based architecture is analyzed in this paper; the proposed architecture uses design-level techniques (such as error detection/correction codes and scrubbing) to make commercially available Dynamic Random Access Memory (DRAM) chips tolerant to faults. This paper provides a complete and novel analysis of engineering alternatives which arise in the design of a highly reliable memory system based on Reed Solomon coding. A comparative analysis of methods for permanent fault detection is provided; moreover using a Markovian characterization, different functional arrangements (based on code and scrubbing frequency) are investigated and evaluated.Gian Carlo Cardarilli received the Laurea (summa cum laude) in 1981 from the University of Rome La Sapienza. He works for the University of Rome Tor Vergata since 1984. At present he is full professor of Digital Electronics and Electronics for Communication Systems at the University of Rome Tor Vergata. During the years 1992–1994 he worked for the University of L Aquila. During the years 1987/1988 he worked for the Circuits and Systems team at EPFL of Lausanne (Switzerland). Professor Cardarilli interests is in the area of VLSI architectures for Signal Processing and IC design. In this field he published over 140 papers in international journals and conferences. He also participated to the work group of JESSI-SMI for the support to the medium and small industries. For this structure he consulted different SMIs, designing a number ASICs, in order to introduce the microelectronics technology in the industry’s products. He has also regular cooperation with companies like Alenia Aerospazio, Rome, Italy, STM, Agrate Brianza, Italy, Micron, Avezzano, Italy, Ericsson Lab, Rome, Italy and with a lot of SMEs. Scientific interests of Professor Cardarilli concern the design of special architectures for signal processing. In particular, he works in the field of computer arithmetic and its application to the design of fast signal digital processor. He also developed mixed-signal neural network architectures implementing them in silicon technology. Recently, he also proposed different new solutions for the implementation of fault-tolerant architectures.Fabrizio Lombardi graduated in 1977 from the University of Essex (UK) with a B.Sc. (Hons.) in Electronic Engineering. In 1977 he joined the Microwave Research Unit at University College London, where he received the Master in Microwaves and Modern Optics (1978), the Diploma in Microwave Engineering (1978) and the Ph.D. from the University of London in 1982.He is currently the holder of the International Test Conference (ITC) Endowed Professorship at Northeastern University, Boston. At the same Institution during the period 1998–2004 he served as Chair of the Department of Electrical and Computer Engineering. Prior to Northeastern University he was a faculty member at Texas Tech University, the University of Colorado-Boulder and Texas A&M University.Dr. Lombardi has received many professional awards: the Visiting Fellowship at the British Columbia Advanced System Institute, University of Victoria, Canada (1988), twice the Texas Experimental Engineering Station Research Fellowship (1991–1992, 1997–1998) the Halliburton Professorship (1995), the Outstanding Engineering Research award at Northeastern University (2004) and an International Research award from the Ministry of Science and Education of Japan (1993–1999). Dr. Lombardi was the recipient of the 1985/86 Research Initiation award from the IEEE/Engineering Foundation and a Silver Quill award from Motorola-Austin (1996).Dr. Lombardi was an Associate Editor (1996–2000) of IEEE Transactions on Computers and a Distinguished Visitor of the IEEE-CS (1990–1993 and 2001–2004). Since 2000, he has been the Associate Editor-In-Chief of IEEE Transactions on Computers and an Associate Editor of the IEEE Design and Test Magazine. Since 2004 he serves as the Chair of the Committee on “Nanotechnology Devices and Systems” of the Test Technology Technical Council of the IEEE.Dr. Lombardi has been involved in organizing many international symposia, conferences and workshops sponsored by professional organizations as well as guest editor of Special Issues in archival journals and magazines such as the IEEE Transactions on Computers, IEEE Transactions on Instrumentation and Measurement, the IEEE Micro Magazine and the IEEE Design & Test Magazine. He is the Founding General Chair of the IEEE Symposium on Network Computing and Applications.His research interests are testing and design of digital systems, quantum and nano computing, ATE systems, configurable/network computing, defect tolerance and CAD VLSI. He has extensively published in these areas and edited six books.Marco Ottavi is currently postdoctoral research associate at the ECE Department of Northeastern University in Boston. He received the Laurea degree in Electronic Engineering from University of Rome “La Sapienza” in 1999 and the Ph.D. in Microelectronics and Telecommunications from University of Rome “Tor Vergata” in 2004. In 2000 he was with ULISSE Consortium, Rome as designer of digital systems for space applications. In 2003 he was visiting research assistant at ECE Department of Northeastern University. His research interests include yield and reliability modeling, fault-tolerant architectures, on-line testing and design of nano scale circuits and systems.Salvatore Pontarelli is currently postdoctoral research associate at the University of Rome, Tor Vergata. He received the Laurea degree in Electronic Engineering from the University of Bologna in 1999 and the Ph.D. in Microelectronics and Telecommunications Engineering from the University of Rome Tor Vergata in 2003. His research mainly focuses on fault tolerance, on-line testing and reconfigurable digital architectures.Adelio Salsano was born in Rome on December 26, 1941 and is currently full professor of Microelectronics at the University of Rome, Tor Vergata where he teaches the courses of Microelectronics and Electronic Programmable Systems. His present research work focuses on the techniques for the design of VLSI circuits, considering both the CAD problems and the architectures for ASIC design. In particular, of relevant interest are the research activities on fault tolerant/fail safe systems for critical environments as space, automotive etc.; on low power systems considering the circuit and architectural points of view; and on fuzzy and neural systems for pattern recognition. An international patent and more than 90 papers on international journals or presented in international meetings are the results of his research activity. At present he is the President of a national consortium named U.L.I.S.S.E., between ten universities, three polytechnics and several of the biggest national industries, as STMicroelectronics, ESAOTE, FINMECCANICA. He is responsible for contracts with the ASI, Italian Space Agency, for the evaluation and use in space environment of COTS circuits and for the definition of new suitable architectures for space applications. Professor Salsano is also involved in professional activities in the field of information technology and is also consultant of many public authorities for specific problems. In particular, he is consultant of the Departments of the Research and of the Industry, of IMI and of other authorities for the evaluation of industrial public and private research projects. Professor Salsano was a member of the consulting Committee for Engineering Sciences of the CNR (National Research Council) from 1981 to 1994 and participated in the design of public research programs in the fields of Telematics, Telemedicine, Office Automation, Telecommunication and, recently, Microelectronics and Bioelectronics.     

Jejunal interposition for peptic stenosis of the esophagus following esophagomyotomy for achalasia

We compared the prognostic significance of prior angina pectoris in 151 patients > or = 75 years of age admitted for acute myocardial infarction. There was a similar in-hospital course, but the long-term outcome was poorer in patients with prior angina.     

Cold air challenge at age 6 and subsequent incidence of asthma. A longitudinal study

The aim of this study was to assess the relation between bronchial hyperresponsiveness to dry, cold air at age 6 and the subsequent incidence of asthma. The cumulative incidence of newly diagnosed asthma between ages 6 and 11 among 360 children included in this study was 12.0%. Survival analysis showed that hyperresponsiveness to cold air at age 6 was associated with an increased risk of developing subsequent asthma (hazard ratio = 2.6, 95% CI = 1.2-5.4; p = 0.01). However, after adjusting for potential confounders, only mild wheezing at age 6 (adjusted hazard ratio 7.5, 95% CI = 3.6-15.9; p < 0.001) and skin test reactivity to allergens at age 6 (adjusted hazard ratio 3.6, 95% CI = 1.5-8.5; p < 0.01), but not hyperresponsiveness to cold air (adjusted hazard ratio = 0.9, 95% CI = 0.4-2.2; p = 0.8), remained significant predictors of subsequent development of asthma. These findings were substantially confirmed after stratifying for wheezing illnesses before age 3. We conclude that hyperresponsiveness to cold air at age 6 was associated with subsequent development of a diagnosis of asthma but this effect was not independent of atopy and mild wheezing at age 6.     

New trends in the clinical use of platelet transfusions

Reference is made to the indications for platelet transfusions, the way in which they are prepared, and the criteria used in assessment of their therapeutic results.     

Immunohistochemical detection of S-100 protein in human deciduous dental pulp

Phlebotomus duboscqi and P. papatasi are morphologically closely related species. Scanning electron microscopy showed constant differences between pharyngeal teeth of the females.     

Spectral analysis of short term R-Tapex interval variability during sinus rhythm and fixed atrial rate

Analysis of heart rate variability has been proven useful in stratifying post myocardial patients at risk and in evaluating autonomic dysfunction. Recently augmented inter-lead variability of the QT interval has been associated with increased mortality as a result of arrhythmia and proposed as a marker of dispersion of ventricular repolarization. As the duration of the QT interval is largely dependent upon the length of the preceding cardiac cycle it is tempting to analyse whether neural mechanisms might also directly exert additional modulation. Using autoregressive algorithms we therefore analysed RR and R-Tapex interval variabilities in 15 normal subjects during sinus rhythm and in six patients with a fixed atrial rate. In controls mean R-Tapex interval and variance measured on the vector magnitude were, respectively, 245 +/- 6 ms and 5.1 +/- 0.7 ms2. Spectral analysis of R-Tapex indicated the presence of two spectral components which corresponded to the low and high frequency components of heart rate variability. In R-Tapex variability, high frequency (44 +/- 4 nu) was predominant over low frequency (29 +/- 4 nu). During controlled respiration, a manoeuvre associated with enhanced vagal modulation of sinus node, there was a further increase in high frequency (58 +/- 4 nu) whereas during tilt the low frequency component of R-Tapex variability became predominant (57 +/- 6 nu). In patients with a fixed atrial rate, variance was extremely low (3 +/- 0.9 ms2) and only a respiration-related high frequency component was recognizable in spectral analysis of RR and R-Tapex variabilities. This component was likely to depend upon mechanically induced changes in cardiac vector orientation. These data indicate that during sinus rhythm short-term R-Tapex interval variability is characterized by the same rhythmical components present in RR variability. However, the presence of a very low variance and of only a high frequency component in patients in whom the physiological variability of sinus node is abolished by atrial pacing. suggests that neural modulatory mechanisms do not exert a direct effect on the length of the R-Tapex interval.     

Labeling of liver and plasma lecithins after injection of 1–2-14C-2-dimethylaminoethanol and14C-L-methionine-methyl to choline deficient rats

Groups of rats were fed a choline-deficient (CD) or a choline-supplemented (CS) diet for 15 hr. Labeling of liver and plasma cephalins and lecithins was followed with time after injection of¹⁴C-L-methionine-methyl or 1–2-¹⁴C-2-dimethylaminoethanol, either alone or together with³H-S-adenosyl-L-methionine-methyl. A reduced concentration of liver and plasma lecithins was found in CD rats. In the same animals, labeling of the phospholipid fractions was considerably greater and faster than in CS rats. Administration of choline to rats previously fed the CD diet resulted in both an increased concentration of liver and plasma lecithins and a reduction in the labeling of liver and plasma lecithins to levels seen in control rats. These results suggest that in CD rats, while the overall synthesis of lecithins may be reduced due to insufficient availability of choline, the synthesis of lecithins via stepwise methylation of cephalins may be increased.     

Un metodo per il calcolo dei nodi e dei pesi delle formule di quadratura di Gauss-Hermite

Sommario In questo lavoro viene presentato un metodo estremamente veloce per il calcolo dei nodi e dei pesi associati nelle formule di quadratura di Gauss-Hermite: tale metodo utilizza matrici facilmente deducibili dalla matrice tridiagonale che può essere associata ad ogni polinomio di Hermite. Sono riportati anche alcuni tempi di esecuzione e risultati numerici.

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We propose a fast method for the calculation of the abscissas and the weights of the Gauss-Hermite quadrature formulas. Such method utilizes matrices easily deducible from the tridiagonal matrix which can be associated with every Hermite polynomials. We relate also some execution's times and numerical results.

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Presentato al Convegno U.M.I. 1975, Cagliari     

Reliability study of duplex-hybrid systems

Duplex (double modular redundant) systems utilising standby spares are described and the reliability equations of such systems are derived. The system reliability as a function of normalised time is plotted and compared with conventional TMR (triple modular redundant) system. It is shown that the duplex-hybrid system is noticeably more reliable than the TMR-hybrid system with the similar configuration of standby spares. Implementation of a duplex-hybrid system supplemented by an intelligent unit with powerful capabilities is discussed.