Table-driven analyses in the SPICE-PAC circuit simulation package

Recent applications of SPICE-PAC to transistor parameter extraction and hierarchical simulation require rather flexible circuit analyses, performed for irregularly distributed values of independent variables. An implementation of table-driven analyses (DC, AC, and time-domain) is described in which tables of arbitrarily distributed independent variables (voltages, frequencies, or timepoints) are used rather than the fixed-step strategy implemented in SPICE-like simulators. Simple examples are used to illustrate applications of table-driven analyses. The simple example of MOS inverter modeling shows that data-driven elements can provide the accuracy needed in practical applications, while reducing significantly the computational effort required for evaluation of complex models of semiconductor device

Table-driven circuit elements in spice-like simulation programs

Table-driven approximation of semiconductor device characteristics and table-driven behavioral descriptions are two particularly attractive examples of enhance- ments that can significantly speed up circuit simula- tion by eliminating many time-consuming calculations in which device voltages and currents are derived from properties and geometries of semiconductor materials. Several extensions to a SPICE-compatible simulation tool are described, that provide table-driven capabili- ties for all nonlinear SPICE circuit elements

Transformations of timed Petri nets and performance analysis

There are two basic approaches to analysis of timed Petri net models, the so called reachability analysis and structural analysis. Reachability analysis is based of the space of reachable states while structural analysis derives properties of models from properties of model components and component interconnections. This paper discusses several simple transformations of timed nets that significantly simplify performance analysis preserving all important performance properties of the original model. In particular, they can convert a model that can be analyzed by the reachability approach only into an equivalent one (with respect to performance) that can be analyzed by structural methods

Service Renaming in Component Composition

In component-based systems, the behavior of components is usually described at component interfaces and the components are characterized as requester (active) and provider (reactive) components. Two interacting components are considered compatible if all possible sequences of services requested by one component can be provided by the other component. This concept of component compatibility can be extended to sets of interacting components, however, in the case of several requester components interacting with one or more provider components, as is typically the case of cleint-server applications, the requests from different components can be interleaved and then verifying component compatibility must take into account all possible interleavings of requests. Such interleaving of requests can lead to unexpected behavior of the composed system, e.g. a deadlock can occur. Service renaming is proposed as a method of systematic eliminating of such unexpected effects and streamlining component compositions

Cytoplasmic Prep1 Interacts with 4EHP Inhibiting Hoxb4 Translation

embryo development. Interestingly, Prep1 contains a putative binding motif for 4EHP, which may reflect a novel unknown function. development effect. mRNA to the 5′ cap structure. This is the first demonstration that a mammalian homeodomain transcription factor regulates translation, and that this function can be possibly essential for the development of female germ cells and involved in mammalian zygote development

mRNA cap analogues substituted in the tetraphosphate chain with CX2: identification of O-to-CCl2 as the first bridging modification that confers resistance to decapping without impairing translation

Analogues of the mRNA 5΄-cap are useful tools for studying mRNA translation and degradation, with emerging potential applications in novel therapeutic interventions including gene therapy. We report the synthesis of novel mono- and dinucleotide cap analogues containing dihalogenmethylenebisphosphonate moiety (i.e. one of the bridging O atom substituted with CCl2 or CF2) and their properties in the context of cellular translational and decapping machineries, compared to phosphate-unmodified and previously reported CH2-substituted caps. The analogues were bound tightly to eukaryotic translation initiation factor 4E (eIF4E), with CCl2-substituted analogues having the highest affinity. When incorporated into mRNA, the CCl2-substituted dinucleotide most efficiently promoted cap-dependent translation. Moreover, the CCl2-analogues were potent inhibitors of translation in rabbit reticulocyte lysate. The crystal structure of eIF4E in complex with the CCl2-analogue revealed a significantly different ligand conformation compared to that of the unmodified cap analogue, which likely contributes to the improved binding. Both CCl2- and CF2- analogues showed lower susceptibility to hydrolysis by the decapping scavenger enzyme (DcpS) and, when incorporated into RNA, conferred stability against major cellular decapping enzyme (Dcp2) to transcripts. Furthermore, the use of difluoromethylene cap analogues was exemplified by the development of 19F NMR assays for DcpS activity and eIF4E binding