Comparison-based diagnosis with faulty comparators

The letter deals with a new approach to diagnosis by comparison. A new class of diagnosable systems is introduced: in these systems, units and comparators used in the diagnostic process may fail. Failure of comparators introduces a new condition of test invalidation for comparison. Characterisation theorems and fault identification similarities between different comparison models are presented.     

Error Tolerant DNA Self-Assembly Using ( $hbox{2}k-hbox{1}$)$times$( $hbox{2}k-hbox{1}$) Snake Tile Sets

DNA self-assembly has been advocated as a possible technique for bottom-up manufacturing of scaffolds for computing systems in the nanoscale region. However, self-assembly is affected by different types of errors (such as growth and facet roughening) that severely limit its applicability. Different methods for reducing the error rate of self-assembly using tiles as basic elements have been proposed. A particularly effective method relies on snake tile sets that utilize a square block of even size (i.e., 2k times 2k tiles, k = 2, 3,.. .). In this paper, an odd-sized square block [i.e., (2k -1) times (2k - 1)] is proposed as basis for the snake tile set. Compared with other tile sets, the proposed snake tile sets achieve a considerable reduction in error rate at a very modest reduction in growth rate. Growth and facet roughening errors are considered and analytical results are presented to prove the reduction in error rate compared with an even-sized snake tile set. Simulation results are provided.     

Use of expert systems in the design of thermal equipment and processes

A study has been carried out on the use of knowledge-based computer-aided design methodology for the design of thermal systems. An expert system is developed using a Prolog-based front end, where the design rules, material databases, computational procedures, and the relevant expert knowledge are implemented. A combination of quantitative and heuristic inputs are employed in the design process. The basic approach employs an iterative redesign strategy, starting with an initial design obtained from the available knowledge base, and the design parameters are iteratively varied until the specified design rules and constraints are satisfied. The general approach can be employed for a variety of thermal systems. The application to a practical system is demonstrated by the design of an electrical furnace used in the thermal processing of materials. The results from the numerical simulation and design of this system are presented to indicate the basic features and the versatility of the expert system.     

Josephson Coupling in Junctions Made of Monolayer Graphene Grown on SiC

Chemical vapor deposition has proved to be successful in producing graphene samples on silicon carbide (SiC) homogeneous at the centimeter scale in terms of Hall conductance quantization. Here, we report on the realization of co-planar diffusive Al/ monolayer graphene/ Al junctions on the same graphene sheet, with separations between the electrodes down to 200 nm. Robust Josephson coupling has been measured for separations not larger than 300 nm. Transport properties are reproducible on different junctions and indicate that graphene on SiC substrates is a concrete candidate to provide scalability of hybrid Josephson graphene/superconductor devices.     

Numerical solution of a stability problem in hydrodynamics

Details are given of techniques used for a numerical integration of the Navier-Stokes equations of hydrodynamics in the neighbourhood of a well-known steady solution (the Couette solution in cylindrical coordinates). A rule of numerical stability for the process of successive approximation is proposed; some preliminary results are described. Questo lavoro contiene i primi risultati di una ricerca sulla integrazione numerica di equazioni differenziali alle derivate parziali, iniziata recentemente presso il C. S. C. E. di Pisa. I primi due autori si sono divisi il compito di impostare il problema e di discutere le questioni di stabilità numerica di cui alla Sezione 5; mentre secondo e terzo autore hanno proposto il metodo di soluzione ed hanno condotto gli esperimenti numerici.     

Flux monitor diode radiation hardness testing

A flux monitor diode is being explored as an option for measurement of the output of an X-ray tube that is used for active transmission measurements on a pipe containing UF₆ gas. The measured flux can be used to correct for any instabilities in the X-ray tube or the high voltage power supply. For this measurement, we are using a silicon junction p-n photodiode, model AXUV100GX, developed by International Radiation Detectors, Inc. (IRD, Inc.). This diode has a silicon thickness of 104 μ and a thin (3-7 nm) silicon dioxide junction passivating, protective entrance window. These diodes have been extensively tested for radiation hardness in the UV range. However, we intend to operate mainly in the 10-40 keV X-ray region. We are performing radiation hardness testing over this energy range, with the energy spectrum that would pass through the diode during normal operation. A long-term measurement was performed at a high flux, which simulated over 80 years of operation. No significant degradation was seen over this time. Fluctuations were found to be within the 0.1% operationally acceptable error range. After irradiation, an I-V characterization showed a temporary irradiation effect which decayed over time. This effect is small because we operate the diode without external bias.     

Allocation and scheduling of Conditional Task Graphs

We propose an original, complete and efficient approach to the allocation and scheduling of Conditional Task Graphs (CTGs). In CTGs, nodes represent activities, some of them are branches and are labeled with a condition, arcs rooted in branch nodes are labeled with condition outcomes and a corresponding probability. A task is executed at run time if the condition outcomes that label the arcs in the path to the task hold at schedule execution time; this can be captured off-line by adopting a stochastic model. Tasks need for their execution either unary or cumulative resources and some tasks can be executed on alternative resources. The solution to the problem is a single assignment of a resource and of a start time to each task so that the allocation and schedule is feasible in each scenario and the expected value of a given objective function is optimized. For this problem we need to extend traditional constraint-based scheduling techniques in two directions: (i) compute the probability of sets of scenarios in polynomial time, in order to get the expected value of the objective function; (ii) define conditional constraints that ensure feasibility in all scenarios. We show the application of this framework on problems with objective functions depending either on the allocation of resources to tasks or on the scheduling part. Also, we present the conditional extension to the timetable global constraint. Experimental results show the effectiveness of the approach on a set of benchmarks taken from the field of embedded system design. Comparing our solver with a scenario based solver proposed in the literature, we show the advantages of our approach both in terms of execution time and solution quality.     

Magnetic resonance butterfly coils: Design and application for hyperpolarized C studies

Hyperpolarized ¹³C magnetic resonance spectroscopy in pig models enables cardiac metabolism assessment and provides a powerful tool for heart physiology studies, although the low molar concentration of derivate metabolites gives rise to technological limitations in terms of data quality. The design of dedicated coils capable of providing large field of view with high Signal-to-Noise Ratio (SNR) data is of fundamental importance.     

Treatment of advanced medullary thyroid carcinoma with a combination of recombinant interferon alpha-2b and octreotide

BACKGROUND: The medical treatment of advanced medullary thyroid carcinoma (MTC) is still questionable. Results of chemotherapy are disappointing with almost no curative responses, few partial responses, and many side-effects. A recent report has suggested the activity of combination recombinant interferon alpha-2b (rIFN-alpha-2b) and octreotide, a somatostatin analogue, in the treatment of a metastatic carcinoid tumor. This new therapeutic schedule may be used in other neuroendocrine tumors. In this study we evaluated the therapeutic effectiveness of octreotide and rIFN-alpha-2b in patients with advanced MTC. METHODS: Eight patients affected by advanced MTC received octreotide at a daily dose of 150 micrograms for 6 months and subsequently at a daily dose of 300 micrograms for another 6 months, subcutaneously, and rIFN-alpha-2b at a daily dose of 5.000.000 IU intramuscularly 3 times a week for 12 months. Plasma calcitonin, carcinoembryonic antigenic levels, and morphologic staging were evaluated at 0, 1, 3, 6, and 12 months. RESULTS: The therapy was stopped in two patients because of diarrhea and toxicity of drugs used. Pre-existing diarrhea in four patients and flushing in one significantly improved during treatment. A maximum decrease of calcitonin was reached after 1 month in 2 patients and after 3 months in 4. In all of the patients carcinoembryonic antigen levels decreased during treatment. No significant changes of size of metastases were observed. CONCLUSIONS: The combination of octreotide and interferon is well tolerated and can be recommended for the treatment of advanced MTC.     

Evaluation and improvement of fault coverage of conformance testingby UIO sequences

The fault coverage of testing protocols using unique input/output (UIO) sequences is analyzed. UIO sequences can be efficiently employed in checking the conformance specifications of protocols by using transition testing. The test sequence is found using the rural Chinese postman tour algorithm. A comprehensive fault model is developed, and analytical expressions are given for the fault coverage. The conditions for undetectability are analyzed, and a new algorithm is proposed. Simulation results and illustrative examples are presented. Overhead issues are discussed, and significant improvements are shown for achieving 100% fault coverage. The major advantage of the proposed approach is that it provides the theoretical basis for fault coverage evaluation of protocol testing using UIO sequences