A Scalable Parallel Algorithm for Reachability Analysis of Very Large Circuits

This paper presents a scalable method for parallelizing symbolic reachability analysis on a distributed-memory environment of workstations. We have developed an adaptive partitioning algorithm that significantly reduces space requirements. The memory balance is maintained by dynamically repartitioning the state space throughout the computation. A compact BDD representation allows coordination by shipping BDDs from one machine to another. This representation allows for different variable orders in the sending and receiving processes. The algorithm uses a distributed termination protocol, with none of the memory modules preserving a complete image of the set of reachable states. No external storage is used on the disk. Rather, we make use of the network, which is much faster.We implemented our method on a standard, loosely-connected environment of workstations, using a high-performance model checker. Initial performance evaluation of several large circuits shows that our method can handle models too large to fit in the memory of a single node. The partitioning algorithm achieves reduction in space, which is linear in the number of workstations employed. A corresponding decrease in space requirements is measured throughout the reachability analysis. Our results show that the relatively slow network does not become a bottleneck, and that computation time is kept reasonably small.     

Rituximab chimeric anti-CD20 monoclonal antibody therapy for relapsed indolent lymphoma: half of patients respond to a four-dose treatment program

PURPOSE: The CD20 antigen is expressed on more than 90% of B-cell lymphomas. It is appealing for targeted therapy, because it does not shed or modulate. A chimeric monoclonal antibody more effectively mediates host effector functions and is itself less immunogenic than are murine antibodies. PATIENTS AND METHODS: This was a multiinstitutional trial of the chimeric anti-CD20 antibody, IDEC-C2B8. Patients with relapsed low grade or follicular lymphoma received an outpatient treatment course of IDEC-C2B8 375 mg/m2 intravenously weekly for four doses. RESULTS: From 31 centers, 166 patients were entered. Of this intent-to-treat group, 48% responded. With a median follow-up duration of 11.8 months, the projected median time to progression for responders is 13.0 months. Serum antibody levels were sustained longer after the fourth infusion than after the first, and were higher in responders and in patients with lower tumor burden. The majority of adverse events occurred during the first infusion and were grade 1 or 2; fever and chills were the most common events. Only 12% of patients had grade 3 and 3% grade 4 toxicities. A human antichimeric antibody was detected in only one patient. CONCLUSION: The response rate of 48% with IDEC-C2B8 is comparable to results with single-agent cytotoxic chemotherapy. Toxicity was mild. Attention needs to be paid to the rate of antibody infusion, with titration according to toxicity. Further investigation of this agent is warranted, including its use in conjunction with standard chemotherapy.     

Young children use motive information to make trait inferences

The present study investigates children's capacity to understand traits in a psychologically meaningful way. Participants included 18 individuals in each of 4 age groups: kindergarten (ages 5-6), 2nd grade (ages 7-8), 5th grade (ages 10-11), and adult. They heard a series of 6 short stories in which a main character performs an action based on a particular motive (positive, negative, or incidental) that results in either a positive or a negative emotional consequence for another character. Participants evaluated each main character and predicted the character's behavior and mental states in different social contexts. Participants in all age groups, even the 5- to 6-year-olds, made trait inferences that were influenced by motive information. These results provide evidence that young children are capable of more sophisticated reasoning about traits than has been suggested previously.     

Explaining characteristic azeotropic behaviour

An explanation of the formation of minimum-boiling, maximum-boiling and saddle-type azeotropes is given (with illustrative examples) in terms of the molecular interactions in the solutions and in the pure liquids. “Interaction weakening” and “interaction strengthening” effects are defined which tend to be associated with the formation of minimum-boiling and maximum-boiling azeotropes respectively. As defined these effects correspond respectively to positive and to negative values of the interchange energy in regular solution theory, though the concept is considered to be of more general application than is this simple model. When more than two components are present it is possible for both effects to occur leading to the possibility of saddle-type azeotropy.By considering the nature of the intermolecular fones it is possible to predict the kind of azeotope which will be formed, if an azeotrope is formed at all. Although present knowledge of intermolecular fones is far from complete, enough is known to enable this prediction to be made in many cases. The more exacting question of whether or not an azeotope will be formed cannot yet be answered with the same certainty partly because of the lack of a completely satisfactory model of the liquid state.     

Grating diffraction and Wood's anomalies at two-dimensionally periodic impedance surfaces

We address the problem of plane-wave scattering and Wood's anomalies at two-dimensional (2-D) periodic surfaces by employing a simplified grating model given by a planar surface whose impedance varies sinusoidally along two orthogonal directions. We obtain a rigorous solution to the corresponding boundary-value problem in terms of an infinite set of coupled recurrence equations. When truncated for computational purposes, this solution is in the form of a banded matrix, which we solve by direct methods and also by a highly efficient iterated matrix procedure. Numerical results are presented for symmetric and nonsymmetric incidence cases, and we show that certain diffracted fields do not depolarize in the former case. The expected Wood's anomalies of both Rayleigh and leaky-wave types are confirmed, and their location in wavelength space is numerically demonstrated for 2-D periodic configurations.     

Managing value-at-risk for a bond using bond put options

This paper studies a strategy that minimizes the Value-at-Risk (VaR) of a position in a zero-coupon bond by buying a percentage of a put option, subject to a fixed budget available for hedging. We elaborate a formula for determining the optimal strike price for this put option in case of a Vasicek stochastic interest rate model. We demonstrate the relevance of searching the optimal strike price, since moving away from the optimum implies a loss, either due to an increased VaR or due to an increased hedging expenditure. In this way, we extend the results of [Ahn, Boudoukh, Richardson, and Whitelaw (1999). Journal of Finance, 54, 359–375] who minimize VaR for a position in a share. In addition, we look at the alternative risk measure Tail Value-at-Risk.     

On the Effective Deployment of Functional Formal Verification

We examine IBM's exploitation of formal verification using RuleBase—a formal verification tool developed by the IBM Haifa Research Laboratory. The goal of the paper is methodological. We identify an integrated methodology for the deployment of formal verification which involves three complementary modes: architectural verification, block-level verification, and design exploration.     

VERTICAL IMPINGING STREAMS AND SPOUTED BED DRYERS COMPARISON AND PERFORMANCE CHARACTERISTICS

A comparison made between spouted-bed and two-impinging-streams reactors proved the superiority of the-impinging-streams dryer The latter device exhibited, on the one hand, relatively small energy requirements for pumping the phases through the reactor and, on the other hand, improved drying characteristics Thus the two-imping-streams reactor is recommended as a useful device for drying operations     

Gaussian beam and pulsed-beam dynamics: complex-source and complex-spectrum formulations within and beyond paraxial asymptotics.

Paraxial Gaussian beams (GB's) are collimated wave objects that have found wide application in optical system analysis and design. A GB propagates in physical space according to well-established quasi-geometric-optical rules that can accommodate weakly inhomogeneous media as well as reflection from and transmission through curved interfaces and thin-lens configurations. We examine the GB concept from a broad perspective in the frequency domain (FD) and the short-pulse time domain (TD) and within as well as arbitrarily beyond the paraxial constraint. For the formal analysis, which is followed by physics-matched high-frequency asymptotics, we use a (space-time)-(wavenumber-frequency) phase-space format to discuss the exact complex-source-point method and the associated asymptotic beam tracking by means of complex rays, the TD pulsed-beam (PB) ultrawideband wave-packet counterpart of the FD GB, GB's and PB's as basis functions for representing arbitrary fields, GB and PB diffraction, and FD-TD radiation from extended continuous aperture distributions in which the GB and the PB bases, installed through windowed transforms, yield numerically compact physics-matched a priori localization in the plane-wave-based nonwindowed spectral representations.     

Weakly dispersive spectral theory of transients, part III: Applications

The spectral theory of transients (STT) formulated in Parts I and II of this paper is here applied to the evaluation of the source-excited pulsed response for a representative class of two-dimensional examples: 1) a dielectric half-space with planar interface, 2) a dielectric half-space with curved interface, and 3) an edge-terminated curved perfectly conducting sheet. These configurations give rise to a variety, of propagation and diffraction phenomena such as those caused by lateral waves, by caustic-forming multiple reflected fields, by edge diffraction with formation of shadow boundaries, and by combinations of these. The results are established by direct utilization of the general formulas in Parts I and II, with emphasis on the spectral features associated with the various wave types. Sketches of the corresponding waveforms elucidate the behavior of the observed signal response.