Tailoring Anderson localization by disorder correlations in 1D speckle potentials

We study Anderson localization of single particles in continuous, correlated, one-dimensional disordered potentials. We show that tailored correlations can completely change the energy-dependence of the localization length. By considering two suitable models of disorder, we explicitly show that disorder correlations can lead to a nonmonotonic behavior of the localization length versus energy. Numerical calculations performed within the transfer-matrix approach and analytical calculations performed within the phase formalism up to order three show excellent agreement and demonstrate the effect. We finally show how the nonmonotonic behavior of the localization length with energy can be observed using expanding ultracold-atom gases

Easily retrievable objects among the NEO population

Asteroids and comets are of strategic importance for science in an effort to understand the formation, evolution and composition of the Solar System. Near-Earth Objects (NEOs) are of particular interest because of their accessibility from Earth, but also because of their speculated wealth of material resources. The exploitation of these resources has long been discussed as a means to lower the cost of future space endeavours. In this paper, we consider the currently known NEO population and define a family of so-called Easily Retrievable Objects (EROs), objects that can be transported from accessible heliocentric orbits into the Earth’s neighbourhood at affordable costs. The asteroid retrieval transfers are sought from the continuum of low energy transfers enabled by the dynamics of invariant manifolds; specifically, the retrieval transfers target planar, vertical Lyapunov and halo orbit families associated with the collinear equilibrium points of the Sun-Earth Circular Restricted Three Body problem. The judicious use of these dynamical features provides the best opportunity to find extremely low energy Earth transfers for asteroid material. A catalogue of asteroid retrieval candidates is then presented. Despite the highly incomplete census of very small asteroids, the ERO catalogue can already be populated with 12 different objects retrievable with less than 500 m/s of Δv. Moreover, the approach proposed represents a robust search and ranking methodology for future retrieval candidates that can be automatically applied to the growing survey of NEOs

Development of in vitro systems to study IFN signalling in gilthead seabream (Sparus aurata)

Type I interferon (IFN I) triggers specific signalling pathways leading to the activation of the innate immune defence of vertebrates against viral infections. In contrats, type II IFN (IFN II) is generally accepted to be part of the adaptive response. Among IFN I-stimulated genes, those coding the Mx proteins play a main role due to the direct antiviral activity of these proteins. The study of Mx genes in gilthead seabream, one of the most important species in the Mediterranean aquaculture, is especially interesting, as this species displays a high natural resistance to viral diseases, and behaves as asymptomatic carrier and/or reservoir of several viruses, such as viral nervous necrosis virus (VNNV), infectious pancreatic necrosis virus (IPNV), and viral haemorrhagic septicaemia virus (VHSV), which are pathogenic to other fish species. Three Mx genes (Mx1, Mx2, and Mx3) have been identified in S. aurata, showing the three proteins a wide spectrum of antiviral activity. The structure of the three promoters (pMx1, pMx2 and pMx3) has been disclosed, and their response to IFN I, IPNV and VHSV indicated a clear induction of the three promoters, with some differences in the kinetics and magnitude of the response. Several studies evidenced the important role of Mx transcription regulation on virus-host interaction: i) Mx promoters can respond to both IFN I and IFN II, thus Mx might be the link between innate and adaptive immunity; ii) Mx activation is blocked by several viruses, thus Mx transcription is the target of their IFN I antagonistic activity; and iii) A fish cell line modified with the promoter of a fish Mx gene was used to measure viraemia in serum with high sensitivity. Therefore, assessing the regulatory mechanisms controlling the transcription of fish Mx genes could significantly contribute to both, understanding virus-host interactions, and designing strategies to control viral infections. In our case, this approach can also give light to understand the successful antiviral strategies developed by gilthead seabream in nature. Thus, the purpose of the present work was to develop three stable transgenic cell lines expressing the firefly luciferase gene under the control of the gilthead seabream Mx promoters. These in vitro systems were established and their response to poly I:C, and to two viral infections was characterized. In the case of IPNV, a clear antagonistic activity was observed for pMx2, as the activity of the promoter was 78.53% lower, however, this effect was not observed for pMx1 and pMx3. When cells were infected with VHSV, no changes in the promoters’ activity were detected, thus indicating that seabream Mx promoters are not targeted by VHSV antagonistic activity. These results confirm the specificity of the interactions between each virus/promoter combination, and support the use of the three cell lines developed as useful tools to characterize virus-host interactions in this species. Further studies aimed at the identification of the molecular mechanisms behind our observations will allow us to get more insight into this complex system.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Polarisation Patterns and Vectorial Defects in Type II Optical Parametric Oscillators

Previous studies of lasers and nonlinear resonators have revealed that the polarisation degree of freedom allows for the formation of polarisation patterns and novel localized structures, such as vectorial defects. Type II optical parametric oscillators are characterised by the fact that the down-converted beams are emitted in orthogonal polarisations. In this paper we show the results of the study of pattern and defect formation and dynamics in a Type II degenerate optical parametric oscillator for which the pump field is not resonated in the cavity. We find that traveling waves are the predominant solutions and that the defects are vectorial dislocations which appear at the boundaries of the regions where traveling waves of different phase or wave-vector orientation are formed. A dislocation is defined by two topological charges, one associated with the phase and another with the wave-vector orientation. We also show how to stabilize a single defect in a realistic experimental situation. The effects of phase mismatch of nonlinear interaction are finally considered.Comment: 38 pages, including 15 figures, LATeX. Related material, including movies, can be obtained from http://www.imedea.uib.es/Nonlinear/research_topics/OPO

Serotonergic Polymorphisms and Psychotic Disorders in Populations From North Spain

There is strong biological evidence relating alterations in the serotonergic system with mental disorders. These alterations may be originated at the DNA level by sequence mutations that alter the functioning of serotonin receptors and transporter. To test this hypothesis we investigated three genetic variants of the 5-HT2A receptor (-1438G/A, 102T/C and His452Tyr) and two variants of the serotonin transporter (a VNTR in the second intron and a 44 bp insertion/delition in the promoter region of the gene) in a clinical sample recruited in a human isolate and in surrounding areas in Northern Spain (N = 257) and in ethnically matched controls (N = 334). No clear association was found between 5-HT2A variants and psychosis. However, marginal associations were observed between the 5-HTT LPR and VNTR variants and psychosis (P < or = 0.05) indicating a minor contribution to psychosis of genetic alterations in this gene

Empirical agent-based modelling of everyday pro-environmental behaviours at work

We report on agent-based modelling work in the LOCAW project (Low Carbon at Work: Modelling Agents and Organisations to Achieve Transition to a Low Carbon Europe). The project explored the effectiveness of various backcasting scenarios conducted with case study organisations in bringing about pro-environmental change in the workforce in the domains of transport, energy use and waste. The model used qualitative representations of workspaces in formalising each scenario, and decision trees learned from questionnaire responses to represent decision-making. We describe the process by which the decision trees were constructed, noting that the use of decision trees in agent-based models requires particular considerations owing to the potential use of explanatory variables in model dynamics. The results of the modelling in various scenarios emphasise the importance of structural environmental changes in facilitating everyday pro-environmental behaviour, but also show there is a role for psychological variables such as norms, values and efficacy. As such, the topology of social interactions is a potentially important driver, raising the interesting prospect that both workplace geography and organisational hierarchy have a role to play in influencing workplace pro-environmental behaviours

Astrometric calibration and performance of the Dark Energy Camera

We characterize the ability of the Dark Energy Camera (DECam) to perform relative astrometry across its 500~Mpix, 3 deg^2 science field of view, and across 4 years of operation. This is done using internal comparisons of ~4x10^7 measurements of high-S/N stellar images obtained in repeat visits to fields of moderate stellar density, with the telescope dithered to move the sources around the array. An empirical astrometric model includes terms for: optical distortions; stray electric fields in the CCD detectors; chromatic terms in the instrumental and atmospheric optics; shifts in CCD relative positions of up to ~10 um when the DECam temperature cycles; and low-order distortions to each exposure from changes in atmospheric refraction and telescope alignment. Errors in this astrometric model are dominated by stochastic variations with typical amplitudes of 10-30 mas (in a 30 s exposure) and 5-10 arcmin coherence length, plausibly attributed to Kolmogorov-spectrum atmospheric turbulence. The size of these atmospheric distortions is not closely related to the seeing. Given an astrometric reference catalog at density ~0.7 arcmin^{-2}, e.g. from Gaia, the typical atmospheric distortions can be interpolated to 7 mas RMS accuracy (for 30 s exposures) with 1 arcmin coherence length for residual errors. Remaining detectable error contributors are 2-4 mas RMS from unmodelled stray electric fields in the devices, and another 2-4 mas RMS from focal plane shifts between camera thermal cycles. Thus the astrometric solution for a single DECam exposure is accurate to 3-6 mas (0.02 pixels, or 300 nm) on the focal plane, plus the stochastic atmospheric distortion.Comment: Submitted to PAS