Complex variable methods and closed form solutions to dynamic crack and punch problems in the classical theory of elasticity

Closed form solutions to dynamical problems in the classical theory of elasticity are rare. In this paper we demonstrate how complex variable techniques may be used to obtain closed form solutions to several problems of practical importance. We consider an elastic strip, and firstly obtain closed form solutions when the surface of the strip is subjected to mixed moving boundary conditions. Next we consider the problem of a pair of punches moving along the lateral boundaries of the strip and opening a crack along the mid surface. To the best of our knowledge the closed form solutions presented are new.     

Complementary solutions of electrostatic field problems

A general error form the corresponds to mismatch in the constitutive relationship is used for systematic derivation of complementary solution formulations, and the associated bounds, in electrostatic field problems. A close kinship between the error-based treatment and a general theorem on well-posed boundary conditions is made use of to highlight the role of boundary specifications in determining the expression for the complementary functionals. A combination of complementary computational results, obtained using two-dimensional finite elements is shown to provide valuable insight into numerical behavior     

A 0.8-μm CMOS technology for high-performance ASIC memory andchannelless gate array

A 0.8-μm polycide-gate, double-layer-metal CMOS technology is described. Nominal device gate lengths down to 0.8 (±0.2) μm are used for both n- and p-channel transistors. Compact isolation, 175-A gate oxide grown in dry/wet/dry ambient, shallow-junction halo-implanted lightly doped drain n and p devices, TiN contact barrier, and a planarized double-layer-metal process are all integrated and demonstrated with a 0.8-μm full-CMOS 16K SRAM (static random-access memory) circuit. The device process integrity, design margins, performance, reliability, product yield and speed enhancement are all discussed in detail     

Formal verification by symbolic evaluation of partially-ordered trajectories

Symbolic trajectory evaluation provides a means to formally verify properties of a sequential system by a modified form of symbolic simulation. The desired system properties are expressed in a notation combining Boolean expressions and the temporal logic next-time operator. In its simplest form, each property is expressed as an assertion [AC], where the antecedentA expresses some assumed conditions on the system state over a bounded time period, and the consequentC expresses conditions that should result. A generalization allows simple invariants to be established and proven automatically.The verifier operates on system models in which the state space is ordered by information content. By suitable restrictions to the specification notation, we guarantee that for every trajectory formula, there is a unique weakest state trajectory that satisfies it. Therefore, we can verify an assertion [AC] by simulating the system over the weakest trajectory forA and testing adherence toC. Also, establishing invariants correspond to simple fixed point calculations.This paper presents the general theory underlying symbolic trajectory evaluation. It also illustrates the application of the theory to the taks of verifying switch-level circuits as well as more abstract implementations.This research was supported by the Defense Advanced Research Projects Agency, ARPA Order Number 4976, by the National Science Foundation, under grant number MIP-8913667, by operating grant OGPO 109688 from the Natural Sciences and Engineering Research Council of Canada, and by a fellowship from the British Columbia Advanced Systems Institute.     

Redox modulation of L-type calcium channels in ferret ventricular myocytes. Dual mechanism regulation by nitric oxide and S-nitrosothiols

The effects of NO-related activity and cellular thiol redox state on basal L-type calcium current, ICa,L, in ferret right ventricular myocytes were studied using the patch clamp technique. SIN-1, which generates both NO. and O2-, either inhibited or stimulated ICa,L. In the presence of superoxide dismutase only inhibition was seen. 8-Br-cGMP also inhibited ICa,L, suggesting that the NO inhibition is cGMP-dependent. On the other hand, S-nitrosothiols (RSNOs), which donate NO+, stimulated ICa,L. RSNO effects were not dependent upon cell permeability, modulation of SR Ca2+ release, activation of kinases, inhibition of phosphatases, or alterations in cGMP levels. Similar activation of ICa,L by thiol oxidants, and reversal by thiol reductants, identifies an allosteric thiol-containing "redox switch" on the L-type calcium channel subunit complex by which NO/O2- and NO+ transfer can exert effects opposite to those produced by NO. In sum, our results suggest that: (a) both indirect (cGMP-dependent) and direct (S-nitrosylation/oxidation) regulation of ventricular ICa,L, and (b) sarcolemma thiol redox state may be an important determinant of ICa,L activity.