2,118 research outputs found
Economic regional impacts of water transfers: the role of factor mobility in a case study of the agricultural sector in the Balearic Islands
Using a CGE model for the Balearic Islands, we simulate the effects of an agricultural water market in the farming sector facing reductions in the water endowment. The market lessens the negative effects on farming communities of short-term water restrictions associated with cyclical droughts. However, in scenarios of permanent reductions, such as those envisaged by global warming predictions or those that result from the implementation of the European Water Framework Directive, a water market may aggravate the negative effects of water shortage. Therefore, the paper shows that generalizations cannot be made about the effects of water markets on farming communities.Agricultural and Food Policy, Environmental Economics and Policy, D58, Q1, Q25, R13,
Charged Particle-like Branes in ABJM: A Summary
We study the effect of adding lower dimensional brane charges to the 't Hooft
monopole, di-baryon and baryon vertex configurations in AdS_4 x CP^3. We show
that these configurations capture the background fluxes in a way that depends
on the induced charges, requiring additional fundamental strings to cancel the
worldvolume tadpoles. The dynamics reveal that the charges must lie inside some
interval, a situation familiar from the baryon vertex in AdS_5 x S^5 with
charges. For the baryon vertex and the di-baryon the number of fundamental
strings must also lie inside an allowed interval. Some ideas about the
existence of these bounds in relation to the stringy exclusion principle are
given.Comment: 6 pages. Contribution to the proceedings of the XVIth European
Workshop on String Theory, Madrid, Spain, June 14-18 2010; based on a talk
given by N. Gutierre
Run-and-Tumble-Like Motion of Active Colloids in Viscoelastic Media
Run-and-tumble (RNT) motion is a prominent locomotion strategy employed by
many living microorganisms. It is characterized by straight swimming intervals
(runs), which are interrupted by sudden reorientation events (tumbles). In
contrast, directional changes of synthetic microswimmers (active particles,
APs) are caused by rotational diffusion, which is superimposed with their
translational motion and thus leads to rather continuous and slow particle
reorientations. Here we demonstrate that active particles can also perform a
swimming motion where translational and orientational changes are disentangled,
similar to RNT. In our system, such motion is realized by a viscoelastic
solvent and a periodic modulation of the self-propulsion velocity.
Experimentally, this is achieved using light-activated Janus colloids, which
are illuminated by a time-dependent laser field. We observe a strong
enhancement of the effective translational and rotational motion when the
modulation time is comparable to the relaxation time of the viscoelastic fluid.
Our findings are explained by the relaxation of the elastic stress, which
builds up during the self-propulsion, and is suddenly released when the
activity is turned off. In addition to a better understanding of active motion
in viscoelastic surroundings, our results may suggest novel steering strategies
for synthetic microswimmers in complex environments.Comment: 6 figures, New Journal of Physics accepte
Hints of 5d Fixed Point Theories from Non-Abelian T-duality
In this paper we investigate the properties of the putative 5d fixed point
theory that should be dual, through the holographic correspondence, to the new
supersymmetric AdS(6) solution constructed in Lozano et al. This solution is
the result of a non-Abelian T-duality transformation on the known
supersymmetric AdS(6) solution of massive Type IIA. The analysis of the charge
quantization conditions seems to put constraints on the global properties of
the background, which, combined with the information extracted from considering
probe branes, suggests a 2-node quiver candidate for the dual CFT.Comment: v2, typos corrected, comments added, to appear in JHE
Supersymmetric AdS_6 via T-duality
We present a new supersymmetric AdS_6 solution of type IIB supergravity with
SU(2) isometry. Through the AdS/CFT correspondence, this has potentially very
interesting implications for 5d fixed point theories. This solution is the
result of a non-Abelian T-duality on the known supersymmetric AdS_6 solution of
massive IIA. The SU(2) R-symmetry is untouched, leading to sixteen supercharges
and preserved supersymmetry.Comment: 4 pages, published versio
Tuning the motility and directionality of self-propelled colloids
Microorganisms are able to overcome the thermal randomness of their
surroundings by harvesting energy to navigate in viscous fluid environments. In
a similar manner, synthetic colloidal microswimmers are capable of mimicking
complex biolocomotion by means of simple self-propulsion mechanisms. Although
experimentally the speed of active particles can be controlled by e.g.
self-generated chemical and thermal gradients, an in-situ change of swimming
direction remains a challenge. In this work, we study self-propulsion of
half-coated spherical colloids in critical binary mixtures and show that the
coupling of local body forces, induced by laser illumination, and the wetting
properties of the colloid, can be used to finely tune both the colloid's
swimming speed and its directionality. We experimentally and numerically
demonstrate that the direction of motion can be reversibly switched by means of
the size and shape of the droplet(s) nucleated around the colloid, depending on
the particle radius and the fluid's ambient temperature. Moreover, the
aforementioned features enable the possibility to realize both negative and
positive phototaxis in light intensity gradients. Our results can be extended
to other types of half-coated microswimmers, provided that both of their
hemispheres are selectively made active but with distinct physical properties.Comment: 12 pages, 5 figures. Scientific Reports (Received: 04 August 2017,
accepted: 04 October 2017, published online: 02 November 2017
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