18,798 research outputs found
An atlas of ECMWF analyses (1980-1987). Part 1: First moment quantities
This document is an atlas of the European Center for Medium Range Weather Forecasts (ECMWF) initialized analyses for 1980 to 1987. Various first moment quantities are presented for monthly, seasonal, and annual averages on a global cylindrical projection, as well as, cross section maps of zonal averages. Global maps of winds, temperature, stream function, and velocity potential are presented at 850 and 200 mb. In addition, global maps of the 300 mb height field (total and eddy), the 500 mb vertical velocity, the 850 mb moisture field, and sea level pressure are presented. The average seasonal cycle and anomalies during the 8 year period are presented for selected quantities
Soft swimming: Exploiting deformable interfaces for low-Reynolds number locomotion
Reciprocal movement cannot be used for locomotion at low-Reynolds number in
an infinite fluid or near a rigid surface. Here we show that this limitation is
relaxed for a body performing reciprocal motions near a deformable interface.
Using physical arguments and scaling relationships, we show that the
nonlinearities arising from reciprocal flow-induced interfacial deformation
rectify the periodic motion of the swimmer, leading to locomotion. Such a
strategy can be used to move toward, away from, and parallel to any deformable
interface as long as the length scales involved are smaller than intrinsic
scales, which we identify. A macro-scale experiment of flapping motion near a
free surface illustrates this new result
Renewable energy from the high seas: geo-spatial modelling of resource potential and legal implications for developing offshore wind projects beyond the national jurisdiction of coastal states
Offshore wind energy projects are currently restricted to the exclusive economic zones of coastal States. Recent advances in technology are raising the prospect of utilising excellent wind resources on the high seas.
Using a global geo-spatial model we identify potential resource areas for this. In the shallow water case for bottom fixed foundations the largest locations are found on the Mascarene Plateau in the Indian Ocean and the Grand Banks in the North Atlantic. The deep water case for floating platforms identifies the largest regions on the Grand Banks/Flemish Cap and Rockall Bank/Hatton Ridge, both in the North Atlantic. The overall legal framework for wind energy projects on the high seas is the United Nations Convention in the Law of the Sea. Flag states will play a central regulatory role for high seas wind energy developments. There is the danger that flags of convenience might evolve and unduly undercut environmental and safety standards that are in place for projects on the territorial sea and EEZ. Such abuse of high seas freedom could compromise the UNCLOS principle of ‘due regard’. Marine spatial planning approaches and the establishment of cooperative mechanisms, led by the IMO, could safeguard against such potential misappropriation
Quantum correlations versus Multisimultaneity: an experimental test
Multisimultaneity is a causal model of relativistic quantum physics which
assigns a real time ordering to any set of events, much in the spirit of the
pilot-wave picture. Contrary to standard quantum mechanics, it predicts a
disappearance of the correlations in a Bell-type experiment when both analysers
are in relative motion such that, each one in its own inertial reference frame,
is first to select the output of the photons. We tested this prediction using
acousto-optic modulators as moving beam-splitters and interferometers separated
by 55 m. We didn't observe any disappearance of the correlations, thus refuting
Multisimultaneity.Comment: 4 pages, 3 figures, RevTex 4 versio
Fast or Frugal, but not both: Decision Heuristics under Time Pressure
Heuristics are simple, yet effective, strategies that people use to make decisions. Because heuristics do not require all available information, they are thought to be easy to implement and to not tax limited cognitive resources, which has led heuristics to be characterized as fast-and-frugal. We question this monolithic conception of heuristics by contrasting the cognitive demands of two popular heuristics, Tallying and Take-the-Best. We contend that heuristics that are frugal in terms of information usage may not always be fast because of the attentional control required to implement this focus in certain contexts. In support of this hypothesis, we find that Take-the-Best, while being more frugal in terms of information usage, is slower to implement and fares worse under time pressure manipulations than Tallying. This effect is then reversed when search costs for Take-the-Best are reduced by changing the format of the stimuli. These findings suggest that heuristics are heterogeneous and should be unpacked according to their cognitive demands to determine the circumstances a heuristic best applies
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