Estimation of saturation and coherence effects in the KGBJS equation - a non-linear CCFM equation

We solve the modified non-linear extension of the CCFM equation - KGBJS equation - numerically for certain initial conditions and compare the resulting gluon Green functions with those obtained from solving the original CCFM equation and the BFKL and BK equations for the same initial conditions. We improve the low transversal momentum behaviour of the KGBJS equation by a small modification

Kinematical constraint effects in the evolution equations based on angular ordering

We study effects of imposing various forms of the kinematical constraints on the full form of the CCFM equation and its non-linear extension. We find that imposing the constraint in its complete form modifies significantly way the shape of gluon density as compared to forms of the constraint used in the numerical calculations and phenomenological applications. In particular the resulting gluon density is suppressed for large values of hard scale related parameter and kT of gluon. This result might be important in description studies of jet correlations at Large Hadron Collider within CCFM approach.Comment: 11 pages, 11 figure

The Flood Last Time: ‘Muck’ and the uses of history in Kara Walker’s ‘Rumination’ on Katrina

Kara Walker describes her book After the Deluge (2007) as “rumination” on Hurricane Katrina structured in the form of a “visual essay.” The book combines Walker's own artwork and the works of other artists into “a narrative of fluid symbols” in which the overarching analogy of “murky, toxic waters” holds the potential to “become the amniotic fluid of a potentially new and difficult birth.” This essay considers Walker's use of history within this collection of images to show how the book opens up ways to interrogate Katrina's particular significance as a wholly new, and yet eerily familiar, historical “event.” Nuancing a reading of Walker's book with reference to James Baldwin's The Fire Next Time (1963), to which After the Deluge implicitly alludes, the essay examines Walker's artistic challenge to the notion that history is a narratable account of a past that precedes the present and demonstrates how that challenge encourages us to think about the potential uses of history within civil rights discourse after Katrina

Identification of the major cause of endemically poor mobilities in SiC/SiO2 structures

Materials with good carrier mobilities are desired for device applications, but in real devices the mobilities are usually limited by the presence of interfaces and contacts. Mobility degradation at semiconductor-dielectric interfaces is generally attributed to defects at the interface or inside the dielectric, as is the case in Si/SiO2 structures, where processing does not introduce detrimental defects in the semiconductor. In the case of SiC/SiO2 structures, a decade of research focused on reducing or passivating interface and oxide defects, but the low mobilities have persisted. By invoking theoretical results and available experimental evidence, we show that thermal oxidation generates carbon di-interstitial defects inside the semiconductor substrate and that they are a major cause of the poor mobility in SiC/SiO2 structures

Tax Cuts in Open Economies

A reduction in income tax rates generates substantial dynamic responses within the framework of the standard neoclassical growth model. The short-run revenue loss after an income tax cut is partly - or, depending on parameter values, even completely - offset by growth in the long-run, due to the resulting incentives to further accumulate capital. We study how the dynamic response of government revenue to a tax cut changes if we allow a Ramsey economy to engage in international trade: the open economy's ability to reallocate resources between labor-intensive and capital-intensive industries reduces the negative effect of factor accumulation on factor returns, thus encouraging the economy to accumulate more than it would do under autarky. We explore the quantitative implications of this intuition for the US in terms of two issues recently treated in the literature: dynamic scoring and the Laffer curve. Our results demonstrate the internaional trade enhances the response of government revenue to tax cuts by a relevant amount. In our benchmark calibration, a reduction in the capital-income tax rate has virtually no effect on government revenue in steady state.international trade, Heckscher-Ohlin, dynamic macroeconomics, taxation, revenue estimation, Laffer curve

Cultural variation in cognitive flexibility reveals diversity in the development of executive functions

Cognitive flexibility, the adaptation of representations and responses to new task demands, improves dramatically in early childhood. It is unclear, however, whether flexibility is a coherent, unitary cognitive trait, or is an emergent dimension of task-specific performance that varies across populations with divergent experiences. Three-to 5-year-old English-speaking U.S. children and Tswana-speaking South African children completed two distinct language-processing cognitive flexibility tests: the FIM-Animates, a word-learning test, and the 3DCCS, a rule-switching test. U.S. and South African children did not differ in word-learning flexibility but showed similar age-related increases. In contrast, U.S. preschoolers showed an age-related increase in rule-switching flexibility but South African children did not. Verbal recall explained additional variance in both tests but did not modulate the interaction between population sample (i.e., country) and task. We hypothesize that rule-switching flexibility might be more dependent upon particular kinds of cultural experiences, whereas word-learning flexibility is less cross-culturally variable