Effect of Triangularity on Ion-Temperature-Gradient-Driven Turbulence

The linear and nonlinear properties of ion-temperature-gradient-driven (ITG) turbulence with adiabatic electrons are modeled for axisymmetric configurations for a broad range of triangularities δ, both negative and positive. Peak linear growth rates decrease with negative δ but increase and shift toward a finite radial wavenumber kx with positive δ. The growth-rate spectrum broadens as a function of kx with negative δ and significantly narrows with positive δ. The effect of triangularity on linear instability properties can be explained through its impact on magnetic polarization and curvature. Nonlinear heat flux is weakly dependent on triangularity for |δ| ≤ 0.5, decreasing significantly with extreme δ, regardless of sign. Zonal modes play an important role in nonlinear saturation in the configurations studied, and artificially suppressing zonal modes increased nonlinear heat flux by a factor of about four for negative δ, increasing with positive δ by almost a factor of 20. Proxies for zonal-flow damping and drive suggest that zonal flows are enhanced with increasing positive δ.</p

Research in development: learning from the CGIAR Research Program on Aquatic Agricultural Systems

This working paper aims to synthesize and share learning from the experience of adapting and operationalizing the Research in Development (RinD) approach to agricultural research in the five hubs under the The CGIAR Research Program on Aquatic Agricultural Systems. It seeks to share learning about how the approach is working in context and to explore the outcomes it is achieving through initial implementation over 3 ½ years. This learning can inform continuation of agricultural research in the second phase of the CGIAR research programs and will be useful to others aiming to implement research programs that seek to equitably build capacity to innovate in complex social-ecological systems. Each of the chapters in this working paper have shown that RinD has produced a range of outcomes that were often unexpected and broader in scope than might result from other approaches to agricultural research. RinD also produces innovations, and there is evidence that it builds capacity to innovate. - See more at: http://www.aas.cgiar.org/publications/research-development-learning-cgiar-research-program-aquatic-agricultural-systems#sthash.xfjhbHpl.dpu

African American English speaking 2nd graders, verbal-s, and educational achievement: Event related potential and math study findings

A number of influential linguistic analyses hold that African American English (AAE) has no verbal-s, the-s that, for example, turns drink into drinks in more mainstream English varieties.On such accounts, sentences like Mary drinks coffee are ungrammatical in AAE. Previous behavioral studies suggest that in addition to being ungrammatical, AAE speaking children find these sentences cognitively demanding, and that their presence in mathematical reasoning tests can depress scores. Until now, however, no online sentence processing study nor investigation of neurophysiological markers has been done to support these findings. Aimed at addressing this gap in the literature, the auditory ERP experiment described herein revealed two different processes associated with AAE speaking 2nd graders listening to this type of sentence: a morphosyntactic structure building problem, reflected in a bilateral early anterior-central negativity; and an increase in working memory load, indicated by a bilateral late long-lasting anterior-central negativity. Study participants also took an orally administered test of math word problems. Consistent with previous findings, results showed they answered fewer questions correctly when those questions contained verbal-s than when they did not

D-brane charges on non-simply connected groups

The maximally symmetric D-branes of string theory on the non-simply connected Lie group SU(n)/Z_d are analysed using conformal field theory methods, and their charges are determined. Unlike the well understood case for simply connected groups, the charge equations do not determine the charges uniquely, and the charge group associated to these D-branes is therefore in general not cyclic. The precise structure of the charge group depends on some number theoretic properties of n, d, and the level of the underlying affine algebra k. The examples of SO(3)=SU(2)/Z_2 and SU(3)/Z_3 are worked out in detail, and the charge groups for SU(n)/Z_d at most levels k are determined explicitly.Comment: 31 pages, 1 figure. 2 refs added. Added the observation: the charge group for each su(2) theory equals the centre of corresponding A-D-E grou

Twisted brane charges for non-simply connected groups

The charges of the twisted branes for strings on the group manifold SU(n)/Z_d are determined. To this end we derive explicit (and remarkably simple) formulae for the relevant NIM-rep coefficients. The charge groups of the twisted and untwisted branes are compared and found to agree for the cases we consider.Comment: 30 page

The charges of a twisted brane

The charges of the twisted D-branes of certain WZW models are determined. The twisted D-branes are labelled by twisted representations of the affine algebra, and their charge is simply the ground state multiplicity of the twisted representation. It is shown that the resulting charge group is isomorphic to the charge group of the untwisted branes, as had been anticipated from a K-theory calculation. Our arguments rely on a number of non-trivial Lie theoretic identities.Comment: 27 pages, 1 figure, harvmac (b

Processing load imposed by line breaks in English temporal Wh-questions

Prosody plays an important role in online sentence processing both explicitly and implicitly. It has been shown that prosodically packaging together parts of a sentence that are interpreted together facilitates processing of the sentence. This applies not only to explicit prosody but also implicit prosody. The present work hypothesizes that a line break in a written text induces an implicit prosodic break, which, in turn, should result in a processing bias for interpreting English wh-questions. Two experiments-one self-paced reading study and one questionnaire study-are reported. Both supported the "line break" hypothesis mentioned above. The results of the self-paced reading experiment showed that unambiguous wh-questions were read faster when the location of line breaks (or frame breaks) matched the scope of a wh-phrase (main or embedded clause) than when they did not. The questionnaire tested sentences with an ambiguous wh-phrase, one that could attach either to the main or the embedded clause. These sentences were interpreted as attaching to the main clause more often than to the embedded clause when a line break appeared after the main verb, but not when it appeared after the embedded verb

Kinetic Turbulence

The weak collisionality typical of turbulence in many diffuse astrophysical plasmas invalidates an MHD description of the turbulent dynamics, motivating the development of a more comprehensive theory of kinetic turbulence. In particular, a kinetic approach is essential for the investigation of the physical mechanisms responsible for the dissipation of astrophysical turbulence and the resulting heating of the plasma. This chapter reviews the limitations of MHD turbulence theory and explains how kinetic considerations may be incorporated to obtain a kinetic theory for astrophysical plasma turbulence. Key questions about the nature of kinetic turbulence that drive current research efforts are identified. A comprehensive model of the kinetic turbulent cascade is presented, with a detailed discussion of each component of the model and a review of supporting and conflicting theoretical, numerical, and observational evidence.Comment: 31 pages, 3 figures, 99 references, Chapter 6 in A. Lazarian et al. (eds.), Magnetic Fields in Diffuse Media, Astrophysics and Space Science Library 407, Springer-Verlag Berlin Heidelberg (2015

Problemas de Relojes. Ejemplos Históricos y Consideraciones Didácticas

Abordamos un problema matemático clásico: aquel en el que se trata de calcular el tiempo que debe transcurrir, a partir de una hora determinada, para que las manecillas de un reloj ocupen una posición concreta. En particular, nos centramos en el caso en que la disposición requerida es que las agujas estén superpuestas. En este artículo, presentamos diversos ejemplos extraídos de textos clásicos y del siglo XIX que ilustran distintos contextos en los que se presenta el problema, así como diferentes métodos de resolución. Además, como consecuencia de dicho análisis, presentamos algunas consideraciones didácticas que pueden motivar el trabajo de estos materiales con profesorado en formación