111 research outputs found
The Giant Inflaton
We investigate a new mechanism for realizing slow roll inflation in string
theory, based on the dynamics of p anti-D3 branes in a class of mildly warped
flux compactifications. Attracted to the bottom of a warped conifold throat,
the anti-branes then cluster due to a novel mechanism wherein the background
flux polarizes in an attempt to screen them. Once they are sufficiently close,
the M units of flux cause the anti-branes to expand into a fuzzy NS5-brane,
which for rather generic choices of p/M will unwrap around the geometry,
decaying into D3-branes via a classical process. We find that the effective
potential governing this evolution possesses several epochs that can
potentially support slow-roll inflation, provided the process can be arranged
to take place at a high enough energy scale, of about one or two orders of
magnitude below the Planck energy; this scale, however, lies just outside the
bounds of our approximations.Comment: 31 pages, 4 figures, LaTeX. v2: references added, typos fixe
Orbital Observations of Dust Lofted by Daytime Convective Turbulence
Over the past several decades, orbital observations of lofted dust have revealed the importance of mineral aerosols as a climate forcing mechanism on both Earth and Mars. Increasingly detailed and diverse data sets have provided an ever-improving understanding of dust sources, transport pathways, and sinks on both planets, but the role of dust in modulating atmospheric processes is complex and not always well understood. We present a review of orbital observations of entrained dust on Earth and Mars, particularly that produced by the dust-laden structures produced by daytime convective turbulence called âdust devilsâ. On Earth, dust devils are thought to contribute only a small fraction of the atmospheric dust budget; accordingly, there are not yet any published accounts of their occurrence from orbit. In contrast, dust devils on Mars are thought to account for several tens of percent of the planetâs atmospheric dust budget; the literature regarding martian dust devils is quite rich. Because terrestrial dust devils may temporarily contribute significantly to local dust loading and lowered air quality, we suggest that martian dust devil studies may inform future studies of convectively-lofted dust on Earth
Self-control interventions for children under age 10 for improving self-control and delinquency and problem behaviors
Self-control improvement programs are intended to serve many purposes, most
notably improving self-control. Yet, interventions such as these often aim to reduce
delinquency and problem behaviors. However, there is currently no summary
statement available regarding whether or not these programs are effective in
improving self-control and reducing delinquency and problem behaviors. The main objective of this review is to assess the available research evidence on the
effect of self-control improvement programs on self-control and delinquency and
problem behaviors. In addition to investigating the overall effect of early selfcontrol
improvement programs, this review will examine, to the extent possible, the
context in which these programs may be most successful. The studies included in this systematic review indicate that self-control
improvement programs are an effective intervention for improving self-control and
reducing delinquency and problem behaviors, and that the effect of these programs
appears to be rather robust across various weighting procedures, and across context,
outcome source, and based on both published and unpublished data
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