9,108 research outputs found

    Book Review: The Beginning and End of Religion

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    A review of The Beginning and End of Religion by Nicholas Lash

    Mechanical chest-compression devices: current and future roles

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    Purpose of review: It is recognised that the quality of CPR is an important predictor of outcome from cardiac arrest yet studies consistently demonstrate that the quality of CPR performed in real life is frequently sub-optimal. Mechanical chest compression devices provide an alternative to manual CPR. This review will consider the evidence and current indications for the use of these devices. Recent findings: Physiological and animal data suggest that mechanical chest compression devices are more effective than manual CPR. However there is no high quality evidence showing improved outcomes in humans. There are specific circumstances where it may not be possible to perform manual CPR effectively e.g. during ambulance transport to hospital, en-route to and during cardiac catheterisation, prior to organ donation and during diagnostic imaging where using these devices may be advantageous. Summary: There is insufficient evidence to recommend the routine use of mechanical chest compression devices. There may be specific circumstances when CPR is difficult or impossible where mechanical devices may play an important role in maintaining circulation. There is an urgent need for definitive clinical and cost effectiveness trials to confirm or refute the place of mechanical chest compression devices during resuscitation

    Code Generation for Efficient Query Processing in Managed Runtimes

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    In this paper we examine opportunities arising from the conver-gence of two trends in data management: in-memory database sys-tems (IMDBs), which have received renewed attention following the availability of affordable, very large main memory systems; and language-integrated query, which transparently integrates database queries with programming languages (thus addressing the famous ‘impedance mismatch ’ problem). Language-integrated query not only gives application developers a more convenient way to query external data sources like IMDBs, but also to use the same querying language to query an application’s in-memory collections. The lat-ter offers further transparency to developers as the query language and all data is represented in the data model of the host program-ming language. However, compared to IMDBs, this additional free-dom comes at a higher cost for query evaluation. Our vision is to improve in-memory query processing of application objects by introducing database technologies to managed runtimes. We focus on querying and we leverage query compilation to im-prove query processing on application objects. We explore dif-ferent query compilation strategies and study how they improve the performance of query processing over application data. We take C] as the host programming language as it supports language-integrated query through the LINQ framework. Our techniques de-liver significant performance improvements over the default LINQ implementation. Our work makes important first steps towards a future where data processing applications will commonly run on machines that can store their entire datasets in-memory, and will be written in a single programming language employing language-integrated query and IMDB-inspired runtimes to provide transparent and highly efficient querying. 1

    Time step rescaling recovers continuous-time dynamical properties for discrete-time Langevin integration of nonequilibrium systems

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    When simulating molecular systems using deterministic equations of motion (e.g., Newtonian dynamics), such equations are generally numerically integrated according to a well-developed set of algorithms that share commonly agreed-upon desirable properties. However, for stochastic equations of motion (e.g., Langevin dynamics), there is still broad disagreement over which integration algorithms are most appropriate. While multiple desiderata have been proposed throughout the literature, consensus on which criteria are important is absent, and no published integration scheme satisfies all desiderata simultaneously. Additional nontrivial complications stem from simulating systems driven out of equilibrium using existing stochastic integration schemes in conjunction with recently-developed nonequilibrium fluctuation theorems. Here, we examine a family of discrete time integration schemes for Langevin dynamics, assessing how each member satisfies a variety of desiderata that have been enumerated in prior efforts to construct suitable Langevin integrators. We show that the incorporation of a novel time step rescaling in the deterministic updates of position and velocity can correct a number of dynamical defects in these integrators. Finally, we identify a particular splitting that has essentially universally appropriate properties for the simulation of Langevin dynamics for molecular systems in equilibrium, nonequilibrium, and path sampling contexts.Comment: 15 pages, 2 figures, and 2 table

    Gold, Fiat Money, and Price Stability

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    Which monetary regime is associated with the most stable price level? A commodity money regime such as the classical gold standard has long been associated with long-run price stability. But critics of the day argued that the regime was associated with too much short-run price variability and argued for reforms that look much like modern versions of price-level targeting. In this paper, we develop a dynamic stochastic general equilibrium model that we use to examine price dynamics under four alternative regimes. They are the gold standard, Irving Fisher's compensated dollar proposal, and two regimes with paper money in which the central bank uses an interest rate rule to run monetary policy. In the first, the central bank uses an interest rate rule to target the price of gold. In the second, there is no convertibility and the central bank targets uses an interest rate rule to target an inflation rate. We find that strict inflation targeting, even though it introduces a unit root into the price level, provides more short-run stability than the gold standard and as much long-term price stability as does the gold standard for horizons shorter than 30 years. We find that Fisher's compensated dollar reduces price level and inflation uncertainty by an order of magnitude at all horizons.

    Discussion of: A statistical analysis of multiple temperature proxies: Are reconstructions of surface temperatures over the last 1000 years reliable?

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    Discussion of "A statistical analysis of multiple temperature proxies: Are reconstructions of surface temperatures over the last 1000 years reliable?" by B.B. McShane and A.J. Wyner [arXiv:1104.4002]Comment: Published in at http://dx.doi.org/10.1214/10-AOAS398F the Annals of Applied Statistics (http://www.imstat.org/aoas/) by the Institute of Mathematical Statistics (http://www.imstat.org

    Multiple Criteria Decision Making: Method Selection And Application To Three Contrasting Agricultural Case Studies

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    Agribusiness, farm business and agricultural-environmental decisions which varied in their characteristics were used to evaluate multiple criteria decision making (MCDM) in an agricultural context. This paper discusses differences between the case studies, strengths and weaknesses of the methods used, and the success of the MCDM process based on participants’ expectations and experiences. While MCDM can help identify the best decision, the main benefits identified in using MCDM included better understanding of their own and other’s perspectives, a means to explain the decision and a structured way to work through the decision process. Key problem areas identified included time limitations, understanding and ownership.Multiple criteria decision making, agriculture, decision making, Agribusiness, Agricultural Finance, Consumer/Household Economics, Crop Production/Industries, Environmental Economics and Policy, Farm Management, Land Economics/Use,

    Epitaxial growth and surface reconstruction of CrSb(0001)

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    Smooth CrSb(0001) films have been grown by molecular beam epitaxy on MnSb(0001) – GaAs(111) substrates. CrSb(0001) shows (2 × 2), triple domain (1 × 4) and (√3×√3)R30° reconstructed surfaces as well as a (1 × 1) phase. The dependence of reconstruction on substrate temperature and incident fluxes is very similar to MnSb(0001)
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