2,988 research outputs found

    Effect of the Butyrate Prodrug Pivaloyloxymethyl Butyrate (AN9) on a Mouse Model for Spinal Muscular Atrophy.

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    Spinal muscular atrophy (SMA) is an early-onset motor neuron disease that leads to loss of muscle function. Butyrate (BA)-based compounds markedly improve the survival and motor phenotype of SMA mice. In this study, we examine the protective effects of the BA prodrug pivaloyloxymethyl butyrate (AN9) on the survival of SMNΔ7 SMA mice. Oral administration of AN9 beginning at PND04 almost doubled the average lifespan of SMNΔ7 SMA mice. AN9 treatment also increased the growth rate of SMNΔ7 SMA mice when compared to vehicle-treated SMNΔ7 SMA mice. In conclusion, BA prodrugs like AN9 have ameliorative effects on SMNΔ7 SMA mice

    Terms of Trade Disturbances, Real Exchange Rates and Welfare: The Role of Capital Controls and Labor Market Distortions

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    Many arguments that have been advanced in favor of maintaining capital control within the EEC have not paid sufficient attention to the welfare consequences of this type of market intervention. Our paper provides a simple, optimizing framework in which the welfare consequences of capital controls can be assessed. Two main issues are considered. First, how do capital controls affect the adjustment of macroeconomic variables to real disturbances? Second, what is the nature of second best arguments for maintaining capital controls given that certain distortions will remain after the European single market is in place in 1992?

    Coherent Reaction

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    Side effects are both the essence and bane of imperative programming. The programmer must carefully coordinate actions to manage their side effects upon each other. Such coordination is complex, error-prone, and fragile. Coherent reaction is a new model of change-driven computation that coordinates effects automatically. State changes trigger events called reactions that in turn change other states. A coherent execution order is one in which each reaction executes before any others that are affected by its changes. A coherent order is discovered iteratively by detecting incoherencies as they occur and backtracking their effects. Unlike alternative solutions, much of the power of imperative programming is retained, as is the common sense notion of mutable state. Automatically coordinating actions lets the programmer express what to do, not when to do it. Coherent reactions are embodied in the Coherence language, which is specialized for interactive applications like those common on the desktop and web. The fundamental building block of Coherence is the dynamically typed mutable tree. The fundamental abstraction mechanism is the virtual tree, whose value is lazily computed, and whose behavior is generated by coherent reactions

    First Class Copy & Paste

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    The Subtext project seeks to make programming fundamentally easier by altering the nature of programming languages and tools. This paper defines an operational semantics for an essential subset of the Subtext language. It also presents a fresh approach to the problems of mutable state, I/O, and concurrency.Inclusions reify copy & paste edits into persistent relationships that propagate changes from their source into their destination. Inclusions formulate a programming language in which there is no distinction between a programÂs representation and its execution. Like spreadsheets, programs are live executions within a persistent runtime, and programming is direct manipulation of these executions via a graphical user interface. There is no need to encode programs into source text.Mutation of state is effected by the computation of hypothetical recursive variants of the state, which can then be lifted into new versions of the state. Transactional concurrency is based upon queued single-threaded execution. Speculative execution of queued hypotheticals provides concurrency as a semantically transparent implementation optimization

    Modular Generation and Customization

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    Modularity and flexibility can conflict in multi-language systems. For example, the templates commonly used to generate web pages must be manually updated when the database schema changes. Modularity can be improved by generating web pages automatically from the database schema, but it is hard for such a generator to produce the same variety of outputs that are easily achieved by ad hoc edits to a template. Ideally, such ad hoc edits would be abstracted into transformations that compose with the generator, offering both modularity and flexibility. However common customizations cannot be abstracted using the standard techniques of textual identifiers and ordinal positions. These difficulties are distilled into a challenge problem to evaluate potential solutions. A solution is proposed based on field trees, a new data model for software artifacts that provides persistent identifiers and unshifting positions within sequences. But using field trees with conventional programming languages and development environments requires more effort than the ad hoc editing they seek to supplant. Field trees are therefore extended into differential trees, which integrate artifacts and their transformations into a unified representation

    Lunar dust transport and potential interactions with power system components

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    The lunar surface is covered by a thick blanket of fine dust. This dust may be readily suspended from the surface and transported by a variety of mechanisms. As a consequence, lunar dust can accumulate on sensitive power components, such as photovoltaic arrays and radiator surfaces, reducing their performance. In addition to natural mechanisms, human activities on the Moon will disturb significant amounts of lunar dust. Of all the mechanisms identified, the most serious is rocket launch and landing. The return of components from the Surveyor 3 provided a rare opportunity to observe the effects of the nearby landing of the Apollo 12 Lunar Module. The evidence proved that significant dust accumulation occurred on the Surveyor at a distance of 155 m. From available information on particle suspension and transport mechanisms, a series of models was developed to predict dust accumulation as a function of distance from the lunar module. The accumulation distribution was extrapolated to a future Lunar Lander scenario. These models indicate that accumulation is expected to be substantial even as far as 2 km from the landing site. Estimates of the performance penalties associated with lunar dust coverage and photovoltaic arrays are presented. Because of the lunar dust adhesive and cohesive properties, the most practical dust defensive strategy appears to be the protection of sensitive components from the arrival of lunar dust by location, orientation, or barriers

    Who Is To Blame? Attribution Theory In The Automotive Industry

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    Automotive manufacturers have a fiduciary duty to the consumer not only to provide transportation from point A to point B; their duty encompasses much more than that. The manufacturer is expected to design, produce, and market vehicles that protect the driver and passengers from bodily harm in the case of an accident. However, sometimes the manufacturer fails in this duty. When this happens, it is imperative that the manufacturer is clear about where and what went wrong. The manufacturer is expected to find an amicable solution to the problem and implement change where needed. We seek to look at what can go wrong, and has gone wrong before, and ask consumers to reflect upon these occurrences and to give a final judgment on who should be held accountable for these injustices. Additionally, we looked at how parts made internally or by an outside supplier change can the consumer’s views

    The influence of process gas type on the enamel surface condition of a high power diode laser generated single-stage ceramic tile grout seal

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    Almost all laser materials processing operations require the simultaneous use of an process or assist gas. This paper examines the use of O2, Ar, N2 and He as process gasses during the firing of a vitreous enamel to form a single-stage ceramic tile grout seal with a high power diode laser (HPDL) and the effects thereof on the surface condition of the glaze. The findings revealed marked differences in the surface condition of the HPDL generated enamel glaze depending upon the process gas used. The use of O2 as the process gas was seen to result in glazes with far fewer microcracks and porosities than those generated with any of the other three gasses, particularly He. Such differences were found to be due to the ability of the smaller O2 gas molecules to dissolve molecularly into the open structure of the HPDL generated enamel glaze and also, the inherent reactiveness of O2 which consequently effects exothermic reactions when it is used as a process gas. Both occurrences were seen, in turn, to affect the cooling rate and therefore the tendency of the molten glaze to generate microcracks when cooled

    A comparative investigation of the wear characteristics of a high power diode laser generated single-stage tile grout and commercial epoxy tile grout

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    A comparative study of a single-stage ceramic tile grout, generated using a 60 W high power diode laser (HPDL), and a commercially available tile grout has determined the wear characteristics of the two materials. Within both normal and corrosive environmental conditions, the single-stage ceramic tile grout proved to have a superior wear rate over the epoxy tile grout, 0.9 mg/cm2/h compared with 125 mg/cm2/h when in an HNO3 environment respectively. Likewise, life assessment testing revealed that the single-stage ceramic tile grout gave an increase in wear life of 4 to 42 times over the commercially available epoxy tile grout, depending upon the corrosive environment. It is believed that the economic and material benefits to be gained from the deployment of such an effective and efficient means of sealing ceramic tiles could be significant
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