75,216 research outputs found
The Benefits of Being Economics Professor A (and not Z)
No full textAlphabetic name ordering on multi-authored academic papers, which is the convention in the economics discipline and various other disciplines, is to the advantage of people whose last name initials are placed early in the alphabet. As it turns out, Professor A, who has been a first author more often than Professor Z, will have published more articles and experienced afaster growth rate over the course of her career as a result of reputation and visibility. Moreover, authors know that name ordering matters and indeed take ordering seriously: Several characteristics of an author group composition determine the decision to deviate from the default alphabetic name order to a significant extent.performance measurement, incentives, economists, name ordering
z-Compact spaces
No full textLindelof spaces, using multifunctions, are given.Our main results are .A space X is z-compact iff for every space Y and z-closed graph multifunction on X into Y the image of every z-closed set in X, is closed in Y. A space X is z-Lindelof iff for every P-space Y and z-closed graph multifunction on X into Y the image of every z-closed set in X is closed in Y
Parallel Algorithms for Maximum Matching in Complements of Interval Graphs and Related Problems
No full textFinal word on Jersey Dutch
No full textIn this article, William Z. Shetter compares and contrasts the dialects that developed between different Dutch colonies in the New World. He explores in-depth the nuances of Jersey Dutch, and provides theories to explain how Dutch and colonial languages blended. The article is reprinted from American Speech, December 1958, Volum XXXIII, No. 4
The Allocation of Resources to Cooperative and Noncooperative R&D
No full textThe precompetitive R&D literature has viewed cooperative and noncooperative R&D as substitutes. In this paper a more realistic approach is taken, where both cooperative and noncooperative R&D are performed in parallel. In the first stage firms determine the optimal investments in both types of R&D, and in the second stage they compete in output. It is found that information sharing between cooperating firms contributes not only to cooperative R&D, but also to noncooperative R&D. The two types of R&D reinforce each other. The level of cooperative R&D may be higher or lower than noncooperative R&D. In a Cournot duopoly, the share of cooperative R&D lies between 20% and 80% of total R&D, and this share increases with spillovers and information sharing. It is always optimal to subsidize half the costs of cooperative R&D, while the subsidy to noncooperative R&D is unchanged form the standard model. Consumers prefer intermediate levels of spillovers and information sharing, while firms prefer higher levels of spillovers, which entail lower levels of information sharing. La littérature sur la R&D préconcurentielle a toujours considéré la coopération et la non-coopération comme des substituts. Dans ce papier, on adopte une approche plus réaliste, où la R&D coopérative et non-coopérative sont effectuées en parallèle. Dans la première étape, les firmes investissent dans les deux types de R&D. Dans la deuxième étape, elles se concurrencent en quantités. Il est démontré que le partage d'information entre les firmes contribue à la R&D non-coopérative, en plus de contribuer à la R&D coopérative. Chaque type de R&D renforce l'autre, impliquant une complémentarité entre les deux. L'investissement en R&D coopérative peut être supérieur ou inférieur à l'investissement en R&D non-coopérative. Dans un duopole de Cournot, la part de la R&D coopérative se situe entre 20% et 80% de la R&D totale, et cette part augmente avec les externalités de recherche et le partage d'information. Il est optimal de subventionner la moitié des coûts de la R&D coopérative, alors que la subvention à la R&D non-coopérative est inchangée par rapport au modèle standard. Les consommateurs préfèrent des niveaux intermédiaires d'externalités de recherche et de partage d'information, alors que les firmes préfèrent des niveaux plus élevés d'externalités, ce qui implique des niveaux très faibles de partage d'information.R&D, cooperative R&D, innovation, R&D subsidies, R&D policy, spillovers, information sharing, R&D, coopération en R&D, innovation, subventions à la recherche, politique de R&D, externalités de recherche, partage d'information
Genetic diversity and population biology of a global collection of phytopathogenic Verticillium dahliae
No full textLogarithmic variance profiles and the corresponding f-1 spectra of temperature fluctuations in turbulent Rayleigh-Bénard convection
No full textWe report experimental results for the temperature variance 2(z) and the corresponding frequency spectra P(f) in turbulent Rayleigh-Bénard convection (RBC) in a cylindrical sample of aspect ratioT= D/L = 1:00 (D = 1:12 m is the diameter and L = 1:12 m the height). The measurements were conducted in the Rayleigh-number range 1011 < Ra < 1:35 1014 and Pr ' 0:8. For Ra = 1:35x1014, 2(z) could be described well by a logarithmic dependence on the vertical position z in a range of z 1 < z < z 2 with z 1 ' 70 and z 2 = 0:1L. Here L=(2Nu) is the thickness of a thin thermal sublayer adjacent to the horizontal plate where the heat flux (denoted by the Nusselt number Nu) is carried mostly by thermal diffusion. In the log layer, we found that the temperature spectra had a significant frequency range over which P(f) f with close to 1. As Ra decreased, increased so that the log layer became thinner. At Ra = 2:05 1011, z 2 < z 1 and therefore there was no range for a log layer. Correspondingly, the temperature spectrum near the horizontal plate did not have the f1 scaling form either
Statistics of the subgrid scales after the shock-turbulence interaction
No full textThe interaction of a normal shock with isotropic turbulence (IT) represents a basic problem for studying some of the phenomena associated with high speed flows, such as hypersonic flight, supersonic combustion and Inertial Confinement Fusion (ICF). In general, in practical applications, the shock width is much smaller than the turbulence scales and the upstream turbulent Mach number is modest. In this case, recent high resolution shock-resolved Direct Numerical Simulations (DNS) (Ryu and Livescu, J. Fluid Mech., 756, R1, 2014) show that the interaction can be described by the Linear Interaction Approximation (LIA). By using LIA to alleviate the need to solve the shock, DNS post-shock data can be generated at much higher Reynolds numbers than previously possible. Here, such results with Taylor Reynolds number around are used to investigate the properties of the subgrid scales (SGS). In particular, it is shown that the shock interaction decreases the asymmetry of the SGS dissipation PDF as the shock Mach number increases, with a significant enhancement in size of the regions and magnitude of backscatter
Transition to turbulence in a qblique shock-wave/boundary-layer interaction at M=15
No full textDirect numerical simulations are carried out for different forcing techniques to trigger transition during the interaction between an oblique shock-wave and a laminar boundary-layer at M = 1.5. Three forcing methods are used: a) forcing of oblique unstable modes, whose shape and behaviour are determined by the local linear stability theory, b) broadband free-stream acoustic disturbances, and c) a cold plasma flow control device. While the oblique-mode breakdown is dominant for low-amplitude forcing, long streaky structures drive the transition process in a high-amplitude disturbance environment. LES are also performed on the experimental setup by the Institute of Theoretical and Applied Mechanics (ITAM) from Novosibirsk State University with cold plasma actuation. As well as the disturbance type, the effect of Reynolds number and forcing amplitude will be investigated
Triangular Constellations in Flows
No full textParticles advected on the surface of a fluid can exhibit fractal clustering. The local structure of a fractal set is described by its dimension , which is the exponent of a power-law relating the mass in a ball to its radius : . It is desirable to characterise the {\em shapes} of constellations of points sampling a fractal measure, as well as their masses. The simplest example is the distribution of shapes of triangles formed by triplets of points, which we investigate for fractals generated by chaotic dynamical systems. The most significant parameter describing the triangle shape is the ratio of its area to the radius of gyration squared. We show that the probability density of has a phase transition: is independent of and approximately uniform below a critical flow compressibility , which we estimate. For the distribution appears to be described by two power laws: when , and when
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