28,262 research outputs found
Discrete logarithms in curves over finite fields
A survey on algorithms for computing discrete logarithms in Jacobians of
curves over finite fields
Revisiting the Lyman Continuum Escape Crisis: Predictions for z > 6 from Local Galaxies
The intrinsic escape fraction of ionizing Lyman continuum photons ()
is crucial to understand whether galaxies are capable of reionizing the neutral
hydrogen in the early universe at z>6. Unfortunately, it is not possible to
access at z>4 with direct observations and the handful of
measurements from low redshift galaxies consistently find < 10%,
while at least ~ 10% is necessary for galaxies dominate reionization.
Here, we present the first empirical prediction of at z>6 by
combining the (sparsely populated) relation between [OIII]/[OII] and
with the redshift evolution of [OIII]/[OII] as predicted from local high-z
analogs selected by their H equivalent-width. We find =
% at z=6 and = % at z=9 for
galaxies with log(M/M) ~ 9.0 (errors given as 1). However,
there is a negative correlation with stellar mass and we find up to 50% larger
per 0.5 dex decrease in stellar mass. The population averaged escape
fraction increases according to = , with
% and at z > 2 for log(M/M)
~ 9.0. With our empirical prediction of (thus fixing an important
previously unknown variable) and further reasonable assumption on clumping
factor and the production efficiency of Lyman continuum photons, we conclude
that the average population of galaxies is just capable to reionize the
universe by z ~ 6.Comment: 10 pages, 4 figure, 1 table. Accepted by Ap
Production of Innovations within Farmer–Researcher Associations Applying Transdisciplinary Research Principles
Small-scale farmers in sub-Saharan West Africa depend heavily on local resources and local knowledge. Science-based knowledge is likely to aid decision-making in complex situations. In this presentation, we highlight a FiBL-coordinated research partnership between three national producer organisations and national agriculture research bodies in Mali, Burkina Faso, and Benin. The partnership seeks to compare conventional, GMObased, and organic cotton systems as regards food security and climate change
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