An actor model of concurrency for the Swift programming language

The Swift programming language is rapidly rising in popularity but it lacks the facilities for true concurrent programming. In this paper we describe an extension to the language which enables access to said concurrent capabilities and provides an api for supporting such interactions. We adopt the ACTOR model of concurrent computation and show how it can be successfully incorporated into the language. We discuss early findings on our prototype implementation and show its usage via an appropriate example. This work also suggests a general design pattern for the implementation of the ACTOR model in the Swift programming language

Thermotropic phase behavior and headgroup interactions of the nonbilayer lipids phosphatidylethanolamine and monogalactosyldiacylglycerol in the dry state

<p>Abstract</p> <p>Background</p> <p>Although biological membranes are organized as lipid bilayers, they contain a substantial fraction of lipids that have a strong tendency to adopt a nonlamellar, most often inverted hexagonal (H_II) phase. The polymorphic phase behavior of such nonbilayer lipids has been studied previously with a variety of methods in the fully hydrated state or at different degrees of dehydration. Here, we present a study of the thermotropic phase behavior of the nonbilayer lipids egg phosphatidylethanolamine (EPE) and monogalactosyldiacylglycerol (MGDG) with a focus on interactions between the lipid molecules in the interfacial and headgroup regions.</p> <p>Results</p> <p>Liposomes were investigated in the dry state by Fourier-transform Infrared (FTIR) spectroscopy and Differential Scanning Calorimetry (DSC). Dry EPE showed a gel to liquid-crystalline phase transition below 0°C and a liquid-crystalline to H_IItransition at 100°C. MGDG, on the other hand, was in the liquid-crystalline phase down to -30°C and showed a nonbilayer transition at about 85°C. Mixtures (1:1 by mass) with two different phosphatidylcholines (PC) formed bilayers with no evidence for nonbilayer transitions up to 120°C. FTIR spectroscopy revealed complex interactions between the nonbilayer lipids and PC. Strong H-bonding interactions occurred between the sugar headgroup of MGDG and the phosphate, carbonyl and choline groups of PC. Similarly, the ethanolamine moiety of EPE was H-bonded to the carbonyl and choline groups of PC and probably interacted through charge pairing with the phosphate group.</p> <p>Conclusions</p> <p>This study provides a comprehensive characterization of dry membranes containing the two most important nonbilayer lipids (PE and MGDG) in living cells. These data will be of particular relevance for the analysis of interactions between membranes and low molecular weight solutes or soluble proteins that are presumably involved in cellular protection during anhydrobiosis.</p

Non Inflammatory Boronate Based Glucose-Responsive Insulin Delivery Systems

Boronic acids, known to bind diols, were screened to identify non-inflammatory cross-linkers for the preparation of glucose sensitive and insulin releasing agglomerates of liposomes (Agglomerated Vesicle Technology-AVT). This was done in order to select a suitable replacement for the previously used cross-linker, ConcanavalinA (ConA), a lectin known to have both toxic and inflammatory effects in vivo. Lead-compounds were selected from screens that involved testing for inflammatory potential, cytotoxicity and glucose-binding. These were then conjugated to insulin-encapsulating nanoparticles and agglomerated via sugar-boronate ester linkages to form AVTs. In vitro, the particles demonstrated triggered release of insulin upon exposure to physiologically relevant concentrations of glucose (10 mmoles/L–40 mmoles/L). The agglomerates were also shown to be responsive to multiple spikes in glucose levels over several hours, releasing insulin at a rate defined by the concentration of the glucose trigger

Enantioselective Protein-Sterol Interactions Mediate Regulation of Both Prokaryotic and Eukaryotic Inward Rectifier K+ Channels by Cholesterol

Cholesterol is the major sterol component of all mammalian cell plasma membranes and plays a critical role in cell function and growth. Previous studies have shown that cholesterol inhibits inward rectifier K+ (Kir) channels, but have not distinguished whether this is due directly to protein-sterol interactions or indirectly to changes in the physical properties of the lipid bilayer. Using purified bacterial and eukaryotic Kir channels reconstituted into liposomes of controlled lipid composition, we demonstrate by 86Rb+ influx assays that bacterial Kir channels (KirBac1.1 and KirBac3.1) and human Kir2.1 are all inhibited by cholesterol, most likely by locking the channels into prolonged closed states, whereas the enantiomer, ent-cholesterol, does not inhibit these channels. These data indicate that cholesterol regulates Kir channels through direct protein-sterol interactions likely taking advantage of an evolutionarily conserved binding pocket

User modelling in search for people with Autism

We present the architecture and prototype imple- mentation of JELLIBEANS, a web search tool for assisting users with Autistic Spectrum Disorder (ASD)1. The system models user interactions within the search process, utilising a user profile, and by integrating insights from the core features of the Autistic condition. The system has an integrated infra-red motion controlled user interface component, utilising gesture and hand movement data to enhance the interactive search process. The work provides insights into how search can be improved for users on the Autistic spectrum and includes an analysis of experiments carried out with the system

First steps in creative computational thinking with natural language programming and Lego MINDSTORMS

We describe the design and implementation of a prototype Android application to help promote the development of creative computational thinking in the UK Key Stage 1 and 2 classroom. The system is based on the combination of a natural language interface and Lego MINDSTORMS robots [1], focussing on engaging children and teachers who would not naturally be interested in computer programming. The prototype was tested with groups of children at local schools. We describe the stages of development for the application and test results. The paper concludes with a brief comparison of other programming applications, and suggests ways forward for the further development of this work

Further exploration with ACTORKIT: an actor model of concurrency

In this paper, we describe further explorations with our prototype architecture and implementation of the Actor model[1] of concurrent computation, ACTORKIT[2][3]. Actors provide a mechanism to exploit the multi-core processors of modern day computer architectures, in an intuitive and natu- ral fashion. ACTORKIT is hosted in an existing programming language as native constructs (Swift). We describe some of our extensions to the language and our experiences with the development, and evolution, of our prototype implementation