Self-checking on-line testable static RAM

This is a fault-tolerant random access memory for use in fault-tolerant computers. It comprises a plurality of memory chips each comprising a plurality of on-line testable and correctable memory cells disposed in rows and columns for holding individually addressable binary bits and provision for error detection incorporated into each memory cell for outputting an error signal whenever a transient error occurs therein. In one embodiment, each of the memory cells comprises a pair of static memory sub-cells for simultaneously receiving and holding a common binary data bit written to the memory cell and the error detection provision comprises comparator logic for continuously sensing and comparing the contents of the memory sub-cells to one another and for outputting the error signal whenever the contents do not match. In another embodiment, each of the memory cells comprises a static memory sub-cell and a dynamic memory sub-cell for simultaneously receiving and holding a common binary data bit written to the memory cell and the error detection provision comprises comparator logic for continuously sensing and comparing the contents of the static memory sub-cell to the dynamic memory sub-cell and for outputting the error signal whenever the contents do not match. Capability for correction of errors is also included

Comparative Direct Analysis of Type Ia Supernova Spectra. V. Insights from A Larger Sample and Quantitative Subclassification

A comparative study of optical spectra of Type Ia supernovae (SNe Ia) is extended, in the light of new data. The discussion is framed in terms of the four groups defined in previous papers of this series: core normal (CN); broad line (BL); cool (CL); and shallow silicon (SS). Emerging features of the SN Ia spectroscopic diversity include evidence (1) that extreme CL SN 1991bg-likes are not a physically distinct subgroup and (2) for the existence of a substantial number of SN 1999aa-like SSs that are very similar to each other and distinguishable from CN even as late as three weeks after maximum light. SN 1999aa-likes may be relatively numerous, yet not a physically distinct subgroup. The efficacy of quantitative spectroscopic subclassification of SNe Ia based on the equivalent widths of absorption features near 5750 A and 6100 A near maximum light is discussed. The absolute magnitude dispersion of a small sample of CNs is no larger than the characteristic absolute magnitude uncertainty.Comment: 32 pages including 14 figures and 1 table, accepted by PAS

Diffusion through the ex vivo vitreal body - bovine, porcine, and ovine models are poor surrogates for the human vitreous

© 2018 The Authors. Published by Elsevier B.V.The human vitreous humour is a complex gel structure whose composition and physical properties can vary considerably from person to person and also change with age. To date, the viscoelastic properties of the human vitreous gel has not been thoroughly investigated and despite many years of intensive research, an ideal vitreous substitute remains a challenge. Understanding the physical structure and properties of the vitreous is of fundamental and therapeutic interest, providing a clear insight into diffusion and transport of administered ophthalmic drug molecules into the vitreous. A number of mammalian surrogates, mainly bovine, porcine and ovine vitreous humours have been greatly used in the literature as a means of studying ophthalmic drug transport and diffusion. In this study, the mechanical, physical and rheological properties of ovine, porcine, and bovine surrogates were investigated and compared to human vitreous. In addition, a bespoke Franz cell construct was used to compare the diffusion of a model drug (i.e. fluorescein) through vitreous samples. Despite the similarity in rheological properties between bovine, porcine and human vitreous samples (p > 0.05), diffusion of fluorescein through the different vitreous samples revealed great differences in values of steady-state flux and diffusion coefficient. In addition, a first-generation vitreous mimic, composed of 4.5 mg/mL hyaluronic acid with complex viscosity of 0.3 ± 0.01 Pa has been evaluated and was demonstrated to be a better mimic of the human vitreous than the mammalian samples investigated.Peer reviewedFinal Published versio

Energy Management for a User Interactive Smart Community: A Stackelberg Game Approach

This paper studies a three party energy management problem in a user interactive smart community that consists of a large number of residential units (RUs) with distributed energy resources (DERs), a shared facility controller (SFC) and the main grid. A Stackelberg game is formulated to benefit both the SFC and RUs, in terms of incurred cost and achieved utility respectively, from their energy trading with each other and the grid. The properties of the game are studied and it is shown that there exists a unique Stackelberg equilibrium (SE). A novel algorithm is proposed that can be implemented in a distributed fashion by both RUs and the SFC to reach the SE. The convergence of the algorithm is also proven, and shown to always reach the SE. Numerical examples are used to assess the properties and effectiveness of the proposed scheme.Comment: 6 pages, 4 figure

Autonomous Butter Robot

Don’t you wish your butter would come to you? Well now it can with the patented Michael and David butter robot! Based on an idea from a TV show, our team set out to see if a similar robot was possible to make in real life. The objective was simple. Can we make a small table sized robot that can bring a person butter using image detection software? With that question in mind we set out buying our components. We wanted to keep it small, so we looked up devices that could do simple image processing and from there we based the robot design off what we thought a small homemade rc car might look like. After continuous testing we found that yes, it is possible to make a small table sized butter robot! Now you won’t even have to get out of your chair to butter your waffles

Feasibility of Using Discriminate Pricing Schemes for Energy Trading in Smart Grid

This paper investigates the feasibility of using a discriminate pricing scheme to offset the inconvenience that is experienced by an energy user (EU) in trading its energy with an energy controller in smart grid. The main objective is to encourage EUs with small distributed energy resources (DERs), or with high sensitivity to their inconvenience, to take part in the energy trading via providing incentive to them with relatively higher payment at the same time as reducing the total cost to the energy controller. The proposed scheme is modeled through a two-stage Stackelberg game that describes the energy trading between a shared facility authority (SFA) and EUs in a smart community. A suitable cost function is proposed for the SFA to leverage the generation of discriminate pricing according to the inconvenience experienced by each EU. It is shown that the game has a unique sub-game perfect equilibrium (SPE), under the certain condition at which the SFA's total cost is minimized, and that each EU receives its best utility according to its associated inconvenience for the given price. A backward induction technique is used to derive a closed form expression for the price function at SPE, and thus the dependency of price on an EU's different decision parameters is explained for the studied system. Numerical examples are provided to show the beneficial properties of the proposed scheme.Comment: 7 pages, 4 figures, 3 tables, conference pape

An Overview of Tissue Engineering as an Alternative for Toxicity Assessment

Tissue engineering is a multidisciplinary field that combines aspects of biology, material sciences, engineering and medicine - the ultimate goal being able to fabricate replacement tissues and/or organs for an ageing population. However, parallel to this milestone, is the exploitation of the biomimetic constructs as feasible alternatives to in vivo/ex vivo toxicity testing models due to their accurate representation of innate tissue and organs. Herein, we summarise a range of concepts within tissue engineering with a particular emphasis on biological material selection and implications to animal testingPeer reviewe

Optimising poly(lactic-co-glycolic acid) microparticle fabrication using a Taguchi orthogonal array design-of-experiment approach

© 2019 Mensah et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.The objective of this study was to identify, understand and generate a Taguchi orthogonal array model for the formation of 10–50 μm microparticles with applications in topical/ocular controlled drug delivery. Poly(lactic-co-glycolic acid) (PLGA) microparticles were fabricated by the single emulsion oil-in-water method and the particle size was characterized using laser diffraction and scanning electronic microscopy (SEM). Sequential Taguchi L 12 and L 18 orthogonal array (OA) designs were employed to study the influence of ten and eight parameters, respectively, on microparticle size (response). The first optimization step using the L 12 design showed that all parameters significantly influenced the particle size of the prepared PLGA microparticles with exception of the concentration of poly(vinyl alcohol) (PVA) in the hardening bath. The smallest mean particle size obtained from the L 12 design was 54.39 μm. A subsequent L 18 design showed that the molecular weight of PLGA does not significantly affect the particle size. An experimental run comprising of defined parameters including molecular weight of PLGA (89 kDa), concentration of PLGA (20% w/v), concentration of PVA in the emulsion (0.8% w/v), solvent type (ethyl acetate), organic/aqeuous phase ratio (1:1 v/v), vortexing speed (9), vortexing duration (60 seconds), concentration of PVA in hardening bath (0.8% w/v), stirring speed of hardening bath (1200 rpm) and solvent evaporation duration (24 hours) resulted in the lowest mean particle size of 23.51 μm which was predicted and confirmed by the L 18 array. A comparable size was demonstrated during the fabrication of BSA-incorporated microparticles. Taguchi OA design proved to be a valuable tool in determining the combination of process parameters that can provide the optimal condition for microparticle formulation. Taguchi OA design can be used to correctly predict the size of microparticles fabricated by the single emulsion process and can therefore, ultimately, save time and costs during the manufacturing process of drug delivery formulations by minimising experimental runs.Peer reviewedFinal Published versio

Population genomic analysis of base composition evolution in Drosophila melanogaster.

The relative importance of mutation, selection, and biased gene conversion to patterns of base composition variation in Drosophila melanogaster, and to a lesser extent, D. simulans, has been investigated for many years. However, genomic data from sufficiently large samples to thoroughly characterize patterns of base composition polymorphism within species have been lacking. Here, we report a genome-wide analysis of coding and noncoding polymorphism in a large sample of inbred D. melanogaster strains from Raleigh, North Carolina. Consistent with previous results, we observed that AT mutations fix more frequently than GC mutations in D. melanogaster. Contrary to predictions of previous models of codon usage in D. melanogaster, we found that synonymous sites segregating for derived AT polymorphisms were less skewed toward low frequencies compared with sites segregating a derived GC polymorphism. However, no such pattern was observed for comparable base composition polymorphisms in noncoding DNA. These results suggest that AT-ending codons could currently be favored by natural selection in the D. melanogaster lineage