18,223 research outputs found

    VALUING AMBIGUITY: THE CASE OF GENETICALLY ENGINEERED GROWTH ENHANCERS

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    A split-valuation method is developed and implemented to elicit the willingness to pay to consume- or avoid consuming- a product of ambiguous quality. The split-valuation method uses experimental auction markets to separate and value the positive and negative attributes of the ambiguous good. The results show that the method can be used to successfully value a good ambiguous quality. Our application reveals that for a sample of students at a midwestern land-grant institution, the average respondent is willing to pay a premium for meat produced with the use of a genetically engineered growth enhancer that has 30% to 60% fewer calories and is 10% to 20% leaner.Consumer/Household Economics,

    Langmuir Wave Generation Through A Neutrino Beam Instability

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    A standard version of a kinetic instability for the generation of Langmuir waves by a beam of electrons is adapted to describe the analogous instability due to a beam of neutrinos. The interaction between a Langmuir wave and a neutrino is treated in the one-loop approximation to lowest order in an expansion in 1/MW21/M_W^2 in the standard electroweak model. It is shown that this kinetic instability is far too weak to occur in a suggested application to the reheating of the plasma behind a stalled shock in a type II supernova (SN). This theory is also used to test the validity of a previous analysis of a reactive neutrino beam instability and various shortcomings of this theory are noted. In particular, it is noted that relativistic plasma effects have a significant effect on the calculated growth rates, and that any theoretical description of neutrino-plasma interactions must be based directly on the electroweak theory. The basic scalings discussed in this paper suggest that a more complete investigation of neutrino-plasma processes should be undertaken to look for an efficient process capable of driving the stalled shock of a type II SN.Comment: 23 pages, incl. 5 postscript figure

    Relativistic quantum plasma dispersion functions

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    Relativistic quantum plasma dispersion functions are defined and the longitudinal and transverse response functions for an electron (plus positron) gas are written in terms of them. The dispersion is separated into Landau-damping, pair-creation and dissipationless regimes. Explicit forms are given for the RQPDFs in the cases of a completely degenerate distribution and a nondegenerate thermal (J\"uttner) distribution. Particular emphasis is placed on the relation between dissipation and dispersion, with the dissipation treated in terms of the imaginary parts of RQPDFs. Comparing the dissipation calculated in this way with the existing treatments leads to the identification of errors in the literature, which we correct. We also comment on a controversy as to whether the dispersion curves in a superdense plasma pass through the region where pair creation is allowed.Comment: 16 pages, 1 figur

    El rol del control personal en la función paliativa de la justificación del sistema entre la población indígena y no indígena de estudiantes peruanos

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    Indexación: Scopus.In this article we propose a mediation model for the association between system justification and psychological well-being (i.e., the palliative function of ideology), based on system justification theory and compensatory control theory. Specifically, we argue that endorsing system-justifying beliefs leads to increased perceived personal control, which in turn predicts higher well-being. We used a convenience sample of students from two Peruvian universities. The results showed that system justification was related to general psychological well-being and personal control. In addition, indigenous students rated lower on system justification, general psychological well-being, self-esteem and personal control. Next, we found that the association between system justification and general psychological well-being was stronger among indigenous students, and this relationship was partially mediated by personal control. In addition, we showed that the mediation model is moderated by ethnicity, so that personal control is a mediator only among non-indigenous participants. We conclude that personal control is a mechanism involved in the palliative function of ideology among this group. Finally, we discuss possible explanations for the mechanisms involved in the palliative function of ideology among low-status individuals. © 2018, © 2018 Fundacion Infancia y Aprendizaje.En este artículo se propone un modelo de mediación de las relaciones entre la justificación del sistema y el bienestar psicológico (i.e., la función paliativa de la ideología) basado en las teorías de la justificación del sistema y del control compensatorio. En concreto, se propone que la adopción de creencias justificativas del sistema produce un aumento del control personal percibido que, a su vez, predice niveles más elevados de bienestar. En este estudio se utilizó una muestra por conveniencia de estudiantes provenientes de dos universidades peruanas. Los resultados muestran que la justificación del sistema está relacionada con el bienestar psicológico general y con el control personal. Además, los estudiantes indígenas mostraron niveles más reducidos de justificación del sistema, bienestar psicológico general, autoestima y control personal. También se observó que la relación entre la justificación del sistema y el bienestar psicológico general era más fuerte entre los estudiantes indígenas y que el control personal mediaba parcialmente en esta relación. Asimismo, mostramos que la etnicidad es un factor moderador del modelo de mediación, por lo que el control personal es un mediador únicamente entre los participantes no indígenas. El estudio concluye que el control personal es un mecanismo que interviene en la función paliativa de la ideología en este grupo. Por último, se discuten posibles explicaciones de los mecanismos implicados en la función paliativa de la ideología entre individuos de estatus social bajo.https://www.tandfonline.com/doi/full/10.1080/02134748.2018.153765

    Reasoning algebraically about refinement on TSO architectures

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    The Total Store Order memory model is widely implemented by modern multicore architectures such as x86, where local buffers are used for optimisation, allowing limited forms of instruction reordering. The presence of buffers and hardware-controlled buffer flushes increases the level of non-determinism from the level specified by a program, complicating the already difficult task of concurrent programming. This paper presents a new notion of refinement for weak memory models, based on the observation that pending writes to a process' local variables may be treated as if the effect of the update has already occurred in shared memory. We develop an interval-based model with algebraic rules for various programming constructs. In this framework, several decomposition rules for our new notion of refinement are developed. We apply our approach to verify the spinlock algorithm from the literature

    Common spaceborne multicomputer operating system and development environment

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    A preliminary technical specification for a multicomputer operating system is developed. The operating system is targeted for spaceborne flight missions and provides a broad range of real-time functionality, dynamic remote code-patching capability, and system fault tolerance and long-term survivability features. Dataflow concepts are used for representing application algorithms. Functional features are included to ensure real-time predictability for a class of algorithms which require data-driven execution on an iterative steady state basis. The development environment supports the development of algorithm code, design of control parameters, performance analysis, simulation of real-time dataflow applications, and compiling and downloading of the resulting application

    Maximal planar networks with large clustering coefficient and power-law degree distribution

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    In this article, we propose a simple rule that generates scale-free networks with very large clustering coefficient and very small average distance. These networks are called {\bf Random Apollonian Networks}(RAN) as they can be considered as a variation of Apollonian networks. We obtain the analytic results of power-law exponent γ=3\gamma =3 and clustering coefficient C=46/3−36ln3/2≈0.74C={46/3}-36\texttt{ln}{3/2}\approx 0.74, which agree very well with the simulation results. We prove that the increasing tendency of average distance of RAN is a little slower than the logarithm of the number of nodes in RAN. Since most real-life networks are both scale-free and small-world networks, RAN may perform well in mimicking the reality. The RAN possess hierarchical structure as C(k)∼k−1C(k)\sim k^{-1} that in accord with the observations of many real-life networks. In addition, we prove that RAN are maximal planar networks, which are of particular practicability for layout of printed circuits and so on. The percolation and epidemic spreading process are also studies and the comparison between RAN and Barab\'{a}si-Albert(BA) as well as Newman-Watts(NW) networks are shown. We find that, when the network order NN(the total number of nodes) is relatively small(as N∼104N\sim 10^4), the performance of RAN under intentional attack is not sensitive to NN, while that of BA networks is much affected by NN. And the diseases spread slower in RAN than BA networks during the outbreaks, indicating that the large clustering coefficient may slower the spreading velocity especially in the outbreaks.Comment: 13 pages, 10 figure

    The UV, Lyman α, and dark matter halo properties of high-redshift galaxies

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    We explore the properties of high-redshift Lyman alpha emitters (LAEs), and their link with the Lyman-break galaxy (LBG) population, using a semi-analytic model of galaxy formation that takes into account resonant scattering of Lyα photons in gas outflows. We can reasonably reproduce the abundances of LAEs and LBGs from z≈3 to 7, as well as most UV luminosity functions (LFs) of LAEs. The stronger dust attenuation for (resonant) Lyα photons compared to UV continuum photons in bright LBGs provides a natural interpretation to the increase of the LAE fraction in LBG samples, XLAE, towards fainter magnitudes. The redshift evolution of XLAE seems however very sensitive to UV magnitudes limits and equivalent width (EW) cuts. In spite of the apparent good match between the statistical properties predicted by the model and the observations, we find that the tail of the Lyα EW distribution (EW≳100 Å) cannot be explained by our model, and we need to invoke additional mechanisms. We find that LAEs and LBGs span a very similar dynamical range, but bright LAEs are ∼4times rarer than LBGs in massive haloes. Moreover, massive haloes mainly contain weak LAEs in our model, which might introduce a bias towards low-mass haloes in surveys which select sources with high-EW cuts. Overall, our results are consistent with the idea that LAEs and LBGs make a very similar galaxy population. Their apparent differences seem mainly due to EW selections, UV detection limits, and a decreasing Lyα to UV escape fraction ratio in high star formation rate galaxie
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