Efficient algorithms for minimum-cost flow problems with piecewise-linear convex costs

We present two efficient algorithms for the minimum-cost flow problem in which arc costs are piecewise-linear and convex. Our algorithms are based on novel algorithms of Orlin, which were developed for the case of linear arc costs. Our first algorithm uses the Edmonds-Karp scaling technique. Its complexity isO(M logU(m+n logM)) for a network withn vertices,m arcs, M linear cost segments, and an upper boundU on the supplies and the capacities. The second algorithm is a strongly polynomial version of the first, and it uses Tardos's idea of contraction. Its complexity isO(M logM(m+n logM)). Both algorithms improve by a factor of at leastM/m the complexity of directly applying existing algorithms to a transformed network in which arc costs are linear.The final stage of this work was performed while Ron Shamir was a visitor at DIMACS (Center for Discrete Mathematics and Theoretical Computer Science), Rutgers University. Supported in part by National Science Foundation Grant NSF-STC88-09648, and by Air Force Grants AFOSR-89-0512 and AFOSR-90-0008.     

On mapping processes to processors in distributed systems

This paper is concerned with the implementation of parallel programs on networks of processors. In particular, we study the use of the network augmenting approach as an implementation tool. According to this approach, the capabilities of a given network of processors can be increased by adding some auxiliary links among the processors. We prove that the minimum set of edges needed to augment a line-like network so that it can accommodate a parallel program is determined by an optimal path cover of the graph representation of the program. Anoptimal path cover of a simple graphG is a set of vertex-disjoint paths that cover all the vertices ofG and has the maximum possible number of edges. We present a linear time optimal path covering algorithm for a class of sparse graphs. This algorithm is of special interest since the optimal path covering problem is NP-complete for general graphs. Our results suggest that a cover and augment scheme can be used for optimal implementation of parallel programs in line-like networks.A preliminary version of this paper was presented at the 6th IEEE Conference on Computer Communications (INFOCOM '87).This reseach is supported in part by National Semiconductor (Israel), Ltd.     

Deuterated target comparison for pyroelectric crystal D-D nuclear fusion experiments

Different target materials were investigated to determine which ones are favorable to increasing the theoretical neutron yield using pyroelectric crystal D-D nuclear fusion. Calculations show that deuterated polyethylene (CD₂) will potentially yield the highest number of neutrons compared to the other targets investigated. However, deuterated plastic targets have been found to erode over the course of experiments.     

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.     

Capacitance voltage characterization of poly SiSiO2Si structures

The high frequency C-V characteristics of poly SiSiO₂Si capacitors have been studied. It is shown that the poly SiSiO₂Si capacitor C-V characteristics are significantly different from the corresponding metal-SiO₂Si capacitor due to field penetration into the poly Si layer. A comparison of the theoretical and measured C-V characteristics gives an estimate of the surface state charge density at the poly SiSiO₂ interface and indicates that the surface potential behavior of this interface is trap and surface state dominated up to poly silicon impurity concentrations of approximately 10¹⁷ cm^?3.     

Learning techniques to train neural networks as a state selectorfor inverter-fed induction machines using direct torque control

Neural networks are receiving attention as controllers for many industrial applications. Although these networks eliminate the need for mathematical models, they require a lot of training to understand the model of a plant or a process. Issues such as learning speed, stability, and weight convergence remain as areas of research and comparison of many training algorithms. This paper discusses the application of neural networks to control induction machines using direct torque control (DTC). A neural network is used to emulate the state selector of the DTC. The training algorithms used in this paper are the backpropagation, adaptive neuron model, extended Kalman filter, and the parallel recursive prediction error. Computer simulations of the motor and neural-network system using the four approaches are presented and compared. Discussions about the parallel recursive prediction error and the extended Kalman filter algorithms as the most promising training techniques is presented, giving their advantages and disadvantages     

Visually evoked cerebral vasomotor response in smoking and nonsmoking young adults, investigated by functional transcranial Doppler

Smoking has been known to cause endothelial dysfunction and is an important risk factor for ischemic stroke. In our study we investigated whether chronic cigarette smoking affects the cerebral blood flow velocity response to a physiological, visual stimulus. By using a visual cortex stimulation paradigm, the flow velocity response in the posterior cerebral arteries (PCA) was measured bilaterally, in 32 young healthy adults (16 smokers, 16 nonsmokers). The stimulation protocol consisted of 10 cycles with a resting phase of 20 s and a stimulating phase of 40 s for each cycle. Besides functional transcranial Doppler (TCD), laboratory tests and measurement of intima-media-thickness (IMT) were also performed. Repeated-measure analysis of variance (ANOVA) was used to detect differences in visually evoked relative flow velocity time courses between smokers and nonsmokers. Repeated-measure ANOVA revealed marked difference in the peak systolic flow velocity time courses between smokers and nonsmokers (p< .001). Maximum percent change of visually evoked flow velocity after visual stimulation was 19+/-4% and 30+/-3% in smokers and nonsmokers, respectively (p< .0001). IMT values did not indicate atherosclerosis in young smokers. Infectious disease and hyperlipidemia were also ruled out by measurement of sensitive C-reactive protein and serum lipids. This is the first functional TCD study demonstrating impaired visually evoked flow velocity response caused by chronic cigarette smoking in otherwise healthy, young subjects. The impaired cerebral vasodilatory mechanism together with atherosclerosis may influence stroke occurrence and outcome in chronic smokers.     

Selective termination and elective reduction in twin pregnancies: 10 years experience at a single centre

Selective termination is employed in multifetal pregnancies, in the presence of an abnormal fetus, in order to improve the prognosis of the normal fetuses. The term elective reduction is used to describe reduction in twin pregnancies for maternal medical conditions, psychological, or socioeconomic reasons. The purpose of this study was to evaluate the factors that influence outcome in such pregnancies. Eighty-two twin pregnancies underwent selective termination (n = 59) or elective reduction (n = 23) over a 10-year period. Early procedures, performed < or = 14 weeks (n = 31), had a pregnancy loss of 9.7% and a mean procedure-to-loss interval of 4.1 +/- 2.8 weeks; mean birthweight was 3299 +/- 395 g in survivors, with a mean gestational age at delivery of 38.4 +/- 2.3 weeks. In comparison, procedures performed > 14 weeks (n = 51) had a pregnancy loss of 7.8%, with a procedure-to-loss interval of 1.2 +/- 0.6 weeks. Mean birthweight was 2577 +/- 999 g, with a mean gestational age at delivery of 35.7 +/- 5 weeks. In conclusion, outcomes were more favourable among patients who underwent a first trimester procedure. The slight increase in pregnancy loss may be attributed to a higher than expected rate of spontaneous abortions in the first trimester, as manifested by the higher procedure-to-loss interval after a first trimester procedure. These facts underscore the importance of early detection of fetal abnormalities in twin pregnancies by ultrasonography and chorionic villus sampling.     

Clinical and immunological study of 7 patients with minocycline-induced autoimmune phenomena

PURPOSE: Prolonged treatment with minocycline for acne vulgaris has been associated with the development of arthralgia, arthritis, and other autoimmune phenomena. We characterized the clinical, laboratory, and immunological profiles of seven patients with this syndrome. SUBJECTS AND METHODS: Clinically the patients were studied with special emphasis on prior minocycline treatment, presenting symptoms, physical findings, course, and outcome. Laboratory tests included fluorescent antinuclear and antineutrophil cytoplasmic (ANCA) antibodies, as well as antibodies to myeloperoxidase, bactericidal permeability increasing protein, elastase, cathepsin G, lactoferrin, cardiolipin, and histone. RESULTS: All 7 patients presented with polyarthritis or arthralgia, morning stiffness, and fever after 6 to 36 months of minocycline treatment. The skin was involved in five patients (three with livedo reticularis and two with subcutaneous nodules). Two patients had chronic active hepatitis. Increased titers of perinuclear ANCA (p-ANCA) were detected in all seven patients; five patients had fluorescent antinuclear antibodies, two had antihistone autoantibodies and one had anticardiolipin antibodies. Antigenic characterization of p-ANCA disclosed antibodies to bactericidal permeability increasing protein in one patient, to elastase in three patients, and to cathepsin G in five patients. Symptoms resolved in five patients upon discontinuation of minocycline; the other two patients were treated with corticosteroids and also achieved remissions. CONCLUSION: Minocycline-induced autoimmune syndrome is characterized by reversible polyarthralgia or arthritis, morning stiffness, fever, frequent skin involvement, occasional chronic active hepatitis, and increased titers of p-ANCA with various minor p-ANCA-related antigens.