Online testing approach for very deep-submicron ICs

Very deep-submicron technologies pose new challenges to IC testing. In particular, crosstalk and transient faults are difficult to detect with traditional methods. Online testing techniques can detect these faults, however, and a new approach extends these techniques to include gross-delay faults. Moreover, this approach described by the authors can be exploited to detect stuck-at and bridging faults offline     

Causality tracking in causal message-logging protocols

Casual message-logging protocols have several attractive properties: they introduce no blocking, send no additional messages over those sent by the application, and never create orphans. Causal message logging, however, does require the casual effects of the deliveries of messages to be tracked. The information concerning causality tracking is piggybacked on application messages, and the amount of such information can become large. In this paper we study the cost of tracking causality in causal message-logging protocols. One can track causality as accurately as possible, but to do so requires piggybacking a considerable amount of additional information. One can reduce the amount of piggybacked information on each message by reducing the accuracy of causality tracking. But then, causal message logging may piggyback the reduced amount of information on more messages. We specify six different methods of tracking causality, each representing a natural choice based on the specification of causal message logging. We describe how these six methods can be implemented and compare them in terms of how large of a piggyback load they impose. This load depends on the application that is using causal message logging. We characterize some applications for which a given method has the smallest piggyback load, and study using simulation the size of the piggyback load for two different models of applications. Received: July 1999 / Accepted: July 2001     

Biosensors based on membrane-bound enzymes immobilized in a 5-(octyldithio)-2-nitrobenzoic acid layer on gold electrodes

Gold electrodes were modified through chemisorption of 5-(octyldithio)-2-nitrobenzoic acid (ODTNB). ODTNB includes a long chain in a short-length thio acid, providing a heterogeneous-like alkanethiol layer after adsorption on gold electrodes. Membrane-bound enzymes, in particular D-fructose dehydrogenase (FDH), D-gluconate dehydrogenase (GADH), and L-lactic dehydrogenase (cytochrome b2) (Cyb2), were immobilized onto ODTNB-modified gold electrodes simply by adsorption. The short-length thio acid may provide electrostatic interactions with enzyme surface charges, while the alkanethiolate enables hydrophobic interaction with the largely lipophilic, membrane-bound enzymes. The immobilization of FDH, GADH, and Cyb2 onto ODTNB-modified gold surfaces has been studied with the quartz crystal microbalance (QCM). Spectrophotometric and electrochemical assays indicate that the immobilized enzyme retains its enzymatic activity after immobilization onto the ODTNB-modified gold surface. The amount of immobilized (and active) enzyme was estimated from QCM to be of the order of 2.5 x 10(-12)-5.3 x 10(-12) mol x cm(-2). A fructose biosensor was developed, making use of a gold surface modified with ODTNB and fructose dehydrogenase, employing hydroxymethylferrocene as a mediator in solution. Calibration curves exhibited a linear relation between the biosensor response and the substrate concentration up to 0.7 mM. Statistical analysis gave an excellent linear correlation (r = 0.9993) and a sensitivity of 6.1 mM(-1) fructose. The biosensor shows a significant stable catalytic current for at least 25 days.     

Peer reviewed: genetic engineering: the frontier of bioremediation

New molecular tools and an improved understanding of biodegradative processes are slowly increasing prospects for successful technology deployment.     

Dithiobissuccinimidyl propionate as an anchor for assembling peroxidases at electrodes surfaces and its application in a H2O2 biosensor

Exposure of gold surfaces to solutions of dithiobis N-succinimidyl propionate (DTSP) gives rise to the modification of the surface with N-succinimidyl-3-thiopropionate (NSTP) which can, in turn, react with amino groups allowing for the covalent immobilization of enzymes such as horseradish peroxidase (HRP). The coverage of NSTP has been estimated to be of the order of 1.3 x 10(-10) from the charge consumed during its reductive desorption. The binding reaction of HRP with NSTP modified gold surfaces has been studied with the quartz crystal microbalance, and the results suggest that the immobilization process involves two steps in which the first (faster) appears to correspond to the rapid incorporation of the enzyme whereas the second is likely due to the slow incorporation of additional enzyme and/or reorganization of the immobilized layer. Spectrophotometric and electrochemical assays indicate that the immobilized HRP retains its enzymatic activity after immobilization onto the DTSP modified gold surface. The amount of immobilized (and active) HRP was estimated from QCM and spectrophotometric measurements to be of the order of 1.5 x 10(-11) mol/cm2. A peroxide biosensor was developed making use of a gold surface modified with DTSP and HRP employing Os and Ru complexes of 1,10-phenanthroline 5,6-dione (phen-dione) of the type [M(phendione)x(L)3-x]+2 (where L = 1,10-phenanthroline or 2,2'-bipyridine, x = 1-3) as mediators with the quinone moieties being the active component. The efficiency of the mediators increased with increasing number of phendione ligands.     

Septo-optic dysplasia: report of 6 patients studied with MR and discussion on its pathogenesis

OBJECTIVE: Septo-optic dysplasia, which consists of the association of the hypoplasia of the optic nerves and the agenesis of the septum pellucidum, is frequently associated with deficiency of hypothalamic releasing factors. In Magnetic Resonance (MR) of these patients, anomalies in the form and size of the pituitary stalk, adenohypophysis and neurohypophysis are found. Some cases show schizencephaly and it has been proposed as an added component of the syndrome by some authors. This fact has been refuted by others. PATIENTS AND METHODS: We present the clinical and neuroanatomic revision of six children with septo-optic dysplasia studied by MR imaging over the last five years in our Department of Neuropediatrics. The aim was, that through the neuroembryological discussion of the morphopathological aspects of the patients, to determine the malformation and the time in which the injury, which was the underlying cause, occurred. RESULTS: From the six cases, in two only disruptive signs were evident with the optic nerves being affected asymmetrically, disruption of the corpus callosum, falx cerebri indemnity and effects in the cortex conformation. This was opposed to the dysgenic features in the other four cases which had no disruptive features. CONCLUSIONS: Our findings suggest that this entity could be the result of at least two different pathogenic processes, that is, a minor form of holoprosencephaly (dysgenesis) or a disruption which, therefore, occurs later in gestation.     

Sensing circuit for on-line detection of delay faults

A sensing circuit for on-line testing of delay faults is presented. It can be used to monitor the outputs of circuits that are either general, or designed to be self-checking with respect to steady-state errors. Detailed analyses of the proposed circuit have shown that it is preferable to alternate solutions from the point of view of both the accuracy and the self-testing capability that make it suitable for self-checking applications. Checking architectures for delay faults, making use of the proposed sensing circuit and of standard checkers, are presented     

Design of CMOS checkers with improved testability of bridging and transistor stuck-on faults

This work presents a design technique for CMOS static and dynamic checkers (to be used in self-checking circuits), that allows the detection of all internal single transistor stuck-on and bridging faults causing unacceptable degradations of the circuit dynamic performance (but not logical errors). Such a technique exploits simple voltage detector circuits to make sure that the intermediate faulty voltages inevitably produced by the faults of interest are always propagated at the checker output as logic errors.With the use of our technique, the main disadvantages of static checkers, so far preventing their use in practical applications, are overcome.The method has been applied to the particular case of two-rail (static as well as dynamic) checkers and its validity has been verified by means of electrical level simulations.     

A novel cartilage protein (CILP) present in the mid-zone of human articular cartilage increases with age

A novel, somewhat basic noncollagenous protein was purified from guanidine hydrochloride extracts of human articular cartilage using cesium chloride density gradient centrifugation, followed by ion-exchange chromatography at pH 5, and gel filtration on two serially coupled columns of Superose 6 and Superdex 200. The protein of 91.5 kDa contains a single polypeptide chain substituted with N-linked oligosaccharides. It appeared unique to cartilage as studied by enzyme-linked immunosorbent assay and immunoblots of various tissue extracts. Its concentration in articular cartilages showed some variability with age being lower in young individuals. It represents a chondrocyte product, since it is synthesized by articular chondrocytes in explant cultures. Interestingly, the distribution of the protein in the articular cartilage provides important information on the nature of chondrocytes at different compartments in the tissue. Thus, chondrocytes in the middle/deeper layers of the tissue in particular, appeared to have produced the protein and deposited it in the interterritorial matrix. The protein was neither seen in the superficial nor in the deepest regions of the articular cartilage. Based on its immunolocalization we have named this protein CILP (cartilage intermediate layer protein).     

Error recovery for ATM transmission over wireless channels

The authors present a technique for efficient recovery from transmission errors to be used when transmitting ATM-like data packets in a wireless channel affected by bursty errors (jamming). Issues related to packet format error protection code structure and retransmission protocol are discussed and simulation results are shown that prove the effectiveness of the proposed approach