Fault-aware Communication Mapping for NoCs with Guaranteed Latency

As feature sizes shrink, transient failures of on-chip network links become a critical problem. At the same time, many applications require guarantees on both message arrival probability and response time. We address the problem of transient link failures by means of temporally and spatially redundant transmission of messages, such that designer-imposed message arrival probabilities are guaranteed. Response time minimisation is achieved by a heuristic that statically assigns multiple copies of each message to network links, intelligently combining temporal and spatial redundancy. Concerns regarding energy consumption are addressed in two ways. First, we reduce the total amount of transmitted messages, and, second, we minimise the application response time such that the resulted time slack can be exploited for energy savings through voltage reduction. The advantages of the proposed approach are guaranteed message arrival probability and guaranteed worst case application response time.     

Polarization independent isolator using spatial walkoff polarizers

A novel type of polarization-independent optical isolator is described which utilizes the polarization walkoff provided by birefringent crystals. Isolation of 44 dB is measured at a wavelength of 1.3 mu m with single-mode fiber insertion loss of 1.5 dB. A temperature-independent scheme is also described that provides at least 39 dB of isolation over the temperature range of 25-75 degrees C.<>     

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PMR1, a Ca2+-ATPase in yeast Golgi, has properties distinct from sarco/endoplasmic reticulum and plasma membrane calcium pumps

PMR1, a P-type ATPase cloned from the yeast Saccharomyces cerevisiae, was previously localized to the Golgi, and shown to be required for normal secretory processes (Antebi, A., and Fink, G.R. (1992) Mol. Biol. Cell 3, 633-654). We provide biochemical evidence that PMR1 is a Ca2+-transporting ATPase in the Golgi, a hitherto unusual location for a Ca2+ pump. As a starting point for structure-function analysis using a mutagenic approach, we used the strong and inducible heat shock promoter to direct high level expression of PMR1 from a multicopy plasmid. Yeast lysates were separated on sucrose density gradients, and fractions assayed for organellar markers. PMR1 is found in fractions containing the Golgi marker guanosine diphosphatase, and is associated with an ATP-dependent, protonophore-insensitive 45Ca2+ uptake activity. This activity is virtually abolished in the absence of the expression plasmid. Furthermore, replacement of the active site aspartate within the phosphorylation domain had the expected effect of abolishing Ca2+ transport activity entirely. Interestingly, the mutant enzymes (Asp-371 --> Glu and Asp-371 --> Asn) demonstrated proper targeting to the Golgi, unlike analogous mutations in the related yeast H+-ATPase. Detailed characterization of calcium transport by PMR1 showed that sensitivity to inhibitors (vanadate, thapsigargin, and cyclopiazonic acid) and affinity for substrates (MgATP and Ca2+) were different from the previously characterized sarco/endoplasmic reticulum and plasma membrane Ca2+-ATPases. PMR1 therefore represents a new and distinct P-type Ca2+-ATPase. Because close homologs of PMR1 have been cloned from rat and other organisms, we suggest that Ca2+-ATPases in the Golgi will form a discrete subgroup that are important for functioning of the secretory pathway.     

Interpretation of long-chain structure from dilute solution properties of ultrahigh molecular weight polymers

Summary Systematic studies on solution properties of ultrahigh molecular weight polymers showed the existence of some special features as compared to usual length polymers. The paper discusses the possible appearance of branched structures in the polymerization process, structures able to influence the mentioned features. From experimental data on poly(methyl methacrylate), poly(butyl methacrylate) and polyacrylonitrile it appears that branching can be excluded, and the very high molecular weight domain considered may be responsible for the modifications observed in the molecular weight dependences on 2>, A₂ or [].     

Allylic polymers from resin acids

An unsaturated adduct has been synthesized by the Diels-Alder reaction between resin acids and diallyl maleate. The obtained polymerizable product can be used both as monomer in the formation of allyl polymers and crosslinking agent. The monomer and its polymers were investigated by usual physical and chemical methods. The synthesized polymers present a linear structure, possibly associated with intramolecular cyclization at low molecular weights, or a three-dimensional structure at high conversions. They are fairly thermostable substances with carboxylic groups in the polymer chain.