2,977 research outputs found
Interaction of density flow and geochemical processes on islands in the Okavanga Delta, Botswana
Addressing structural uncertainty of groundwater model predictions with ensemble of automatically generated models from AEM geophysical data and borehole data
Operational river discharge forecasting in poorly gauged basins: the Kavango River Basin case study
Operational probabilistic forecasts of river discharge are essential for
effective water resources management. Many studies have addressed this topic
using different approaches ranging from purely statistical black-box
approaches to physically based and distributed modeling schemes employing
data assimilation techniques. However, few studies have attempted to develop
operational probabilistic forecasting approaches for large and poorly gauged
river basins. The objective of this study is to develop open-source software
tools to support hydrologic forecasting and integrated water resources
management in Africa. We present an operational probabilistic forecasting
approach which uses public-domain climate forcing data and a
hydrologic–hydrodynamic model which is entirely based on open-source
software. Data assimilation techniques are used to inform the forecasts with
the latest available observations. Forecasts are produced in real time for
lead times of 0–7 days. The operational probabilistic forecasts are
evaluated using a selection of performance statistics and indicators and the
performance is compared to persistence and climatology benchmarks. The
forecasting system delivers useful forecasts for the Kavango River, which
are reliable and sharp. Results indicate that the value of the forecasts is
greatest for intermediate lead times between 4 and 7 days
Operational river discharge forecasting in poorly gauged basins: the Kavango River Basin case study
NEOWISE-R Observation of the Coolest Known Brown Dwarf
The Wide-field Infrared Survey Explorer (WISE) spacecraft has been
reactivated as NEOWISE-R to characterize and search for Near Earth Objects. The
brown dwarf WISE J085510.83-071442.5 has now been reobserved by NEOWISE-R, and
we confirm the results of Luhman (2014b), who found a very low effective
temperature ( K), a very high proper motion (8.1 +/- 0.1
arcsec/yr) , and a large parallax (454 +/- 45 mas). The large proper motion has
separated the brown dwarf from the background sources that influenced the 2010
WISE data, allowing a measurement of a very red WISE color of W1-W2
mag. A re-analysis of the 2010 WISE astrometry using only the W2 band, combined
with the new NEOWISE-R 2014 position, gives an improved parallax of 448 +/- 33
mas and proper motion of 8.08 +/- 0.05\; arcsec/yr. These are all consistent
with Luhman (2014b).Comment: 6 pages, AJ accepte
Projected free energies for polydisperse phase equilibria
A `polydisperse' system has an infinite number of conserved densities. We
give a rational procedure for projecting its infinite-dimensional free energy
surface onto a subspace comprising a finite number of linear combinations of
densities (`moments'), in which the phase behavior is then found as usual. If
the excess free energy of the system depends only on the moments used, exact
cloud, shadow and spinodal curves result; two- and multi-phase regions are
approximate, but refinable indefinitely by adding extra moments. The approach
is computationally robust and gives new geometrical insights into the
thermodynamics of polydispersity.Comment: 4 pages, REVTeX, uses multicol.sty and epsf.sty, 1 postscript figure
include
Biologically Relevant Small Radicals
Biologically relevant small radicals are at the focus of the working group 4 (WG4) of the COST Action CM0603 (Free Radicals in Chemical Biology, CHEMBIORADICAL). This article surveys the areas of research being undertaken by the partners in WG4. The character of the radicals is described
together with experimental techniques utilized to follow their structure and reactivity. Specifically, C-, S-, N- and O-centered radicals of small size, and their interaction with different biomolecules are described. Processes at the molecular level exemplifying important biological signaling
and damaging pathways are introduced
Different steady states for spin currents in noncollinear multilayers
We find there are at least two different steady states for transport across
noncollinear magnetic multilayers. In the conventional one there is a
discontinuity in the spin current across the interfaces which has been
identified as the source of current induced magnetic reversal; in the one
advocated herein the spin torque arises from the spin accumulation transverse
to the magnetization of a magnetic layer. These two states have quite different
attributes which should be discerned by current experiments.Comment: 8 pages, no figure. Accepted for publication in Journal of Physics:
Condensed Matte
Planning infrastructure within the Zambezi water-energy-food nexus under uncertainties and climate change
Classification of the Nuclear Multifragmentation Phase Transition
Using a recently proposed classification scheme for phase transitions in
finite systems [Phys.Rev.Lett.{\bf 84},3511 (2000)] we show that within the
statistical standard model of nuclear multifragmentation the predicted phase
transition is of first order.Comment: 5 pages, 4 eps figures, accepted for publication in Phys.Rev.C (in
press
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