Optimizing Integrated Information with a Prior Guided Random Search Algorithm

Integrated information theory (IIT) is a theoretical framework that provides a quantitative measure to estimate when a physical system is conscious, its degree of consciousness, and the complexity of the qualia space that the system is experiencing. Formally, IIT rests on the assumption that if a surrogate physical system can fully embed the phenomenological properties of consciousness, then the system properties must be constrained by the properties of the qualia being experienced. Following this assumption, IIT represents the physical system as a network of interconnected elements that can be thought of as a probabilistic causal graph, $\mathcal{G}$, where each node has an input-output function and all the graph is encoded in a transition probability matrix. Consequently, IIT's quantitative measure of consciousness, $\Phi$, is computed with respect to the transition probability matrix and the present state of the graph. In this paper, we provide a random search algorithm that is able to optimize $\Phi$ in order to investigate, as the number of nodes increases, the structure of the graphs that have higher $\Phi$. We also provide arguments that show the difficulties of applying more complex black-box search algorithms, such as Bayesian optimization or metaheuristics, in this particular problem. Additionally, we suggest specific research lines for these techniques to enhance the search algorithm that guarantees maximal $\Phi$

Absence of charge backscattering in the nonequilibrium current of normal-superconductor structures

We study the nonequilibrium transport properties of a normal-superconductor-normal structure, focussing on the effect of adding an impurity in the superconducting region. Current conservation requires the superfluid velocity to be nonzero, causing a distortion of the quasiparticle dispersion relation within the superconductor. For weakly reflecting interfaces we find a regime of intermediate voltages in which Andreev transmission is the only permitted mechanism for quasiparticles to enter the superconductor. Impurities in the superconductor can only cause Andreev reflection of these quasiparticles and thus cannot degrade the current. At higher voltages, a state of gapless superconductivity develops which is sensitive to the presence of impurities.Comment: Latex file, 11 pages, 2 figures available upon request [email protected], to be published in Journal of Physics: Condensed Matte

Self-consistent scattering description of transport in normal-superconductor structures

We present a scattering description of transport in several normal-superconductor structures. We show that the related requirements of self-consistency and current conservation introduce qualitative changes in the transport behavior when the current in the superconductor is not negligible. The energy thresholds for quasiparticle propagation in the superconductor are sensitive to the existence of condensate flow ($v_s\neq 0$). This dependence is responsible for a rich variety of transport regimes, including a voltage range in which only Andreev transmission is possible at the interfaces, and a state of gapless superconductivity which may survive up to high voltages if temperature is low. The two main effects of current conservation are a shift towards lower voltages of the first peak in the differential conductance and an enhancement of current caused by the greater availability of charge transmitting scattering channels.Comment: 31 pages, 10 PS figures, Latex file, psfig.sty file is added. To appear in Phys. Rev. B (Jan 97

Giant Conductance Oscillations In Mesoscopic Andreev Interferometers

We analyze the electrical conductance $G(\phi)$ of a two-dimensional, phase coherent structure in contact with two superconductors, which is known to be an oscillatory function of the phase difference $\phi$ between the superconductors. It is predicted that for a metallic sample, the amplitude of oscillation is enhanced by placing a normal barrier at the interface and that, by tuning the strength of the barrier, can be orders of magnitude greater than values observed in recent experiments. Giant oscillations can also be obtained without a barrier, provided a crucial sum rule is broken. This can be achieved by disorder induced normal scattering. In the absence of zero phase inter-channel scattering, the conductance possesses a zero phase minimum.Comment: 4 pages of Revtex, 6 figures available on reques

Lower relative differential expression of two genes is associated with delayed ripening in melon

[SPA] Con el fin de comparar la expresión génica de un melón cerca de la línea isogénica (NIL) SC10-2 y su parental Piel de Sapo (PS) durante la maduración y para comprender los mecanismos de diferenciación, se realizó una secuenciación transcriptoma. Dos genes de CmGGP (GDP-L-galactosa fosforilasa 1) y CmRAP2-11 (factor de transcripción sensible al etileno RAP2-11) mostraron menor expresión relativa en la NIL SC10 -2 versus PS debido a la introgresión en LG X. Sin embargo, no existieron diferencias en expresión de CmAP2-like X1 (factor de transcripción sensible al etileno, similar a AP2 TOE3 isoforma X1). En consecuencia, la expresión de genes que mapearon en el grupo de ligamiento X como un factor de transcripción de respuesta a etileno o del metabolismo del ácido ascórbico estuvieron probablemente asociados con el retraso de maduración. [ENG] The expression of selected genes during ripening was studied considering a melon Near-isogenic Line (NIL) SC10-2 and its parental “Piel de Sapo” (PS). The expression of CmGGP (GDP-L-galactose phosphorylase 1), CmAP2-like X1 (AP2-like ethylene-responsive transcription factor TOE3 isoform X1) and CmRAP2-11 (ethylene-responsive transcription factor RAP2-11) were differentially expressed in the NIL SC10-2 compared with PS. Consequently, expression of genes that mapped in LG X such as one ethylene response transcription factors or ascorbic acid metabolism gene were probably associated with delayed ripening.Financial support: Fundación Séneca de la Región de Murcia (11784/PI/09), MINECO & UE-FEDER funds (AGL2010-20858). Thanks for the technical assistance to P. Varó and his team in CIFEA-Torre Pacheco (Consejería de Agricultura, Región de Murcia) for crop management and IRTA-CRAG for the seeds of the NIL

Dynamics of conversion of supercurrents into normal currents, and vice versa

The generation and destruction of the supercurrent in a superconductor (S) between two resistive normal (N) current leads connected to a current source is computed from the source equation for the supercurrent density. This equation relates the gradient of the pair potential's phase to electron and hole wavepackets that create and destroy Cooper pairs in the N/S interfaces. Total Andreev reflection and supercurrent transmission of electrons and holes are coupled together by the phase rigidity of the non-bosonic Cooper-pair condensate. The calculations are illustrated by snapshots from a computer film.Comment: 8 pages, 1 figure, accepted by Phys. Rev.

s-s*-d-wave superconductor on a square lattice and its BCs phase diagram

We study an extended Hubbard model with on-site repulsion and nearest neighbors attraction which tries to mimic some of the experimental features of doped cuprates in the superconducting state. We draw and discuss the phase diagram as a function of the effective interactions among electrons for a wide range of doping concentrations. We locate the region which is relevant for the cuprates setting some constraints on the parameters which may be used in this kind of effective models. We also study the effects of temperature and orthorrombicity on the symmetry and magnitude of the gap function, and map the model onto a simpler linearized hamiltonian, which produces similar phase diagrams.Comment: 4 pages, 3 figures included. Accepted for publication in Phys. Rev.

Policing the legume-Rhizobium symbiosis: a critical test of partner choice

In legume-Rhizobium symbioses, specialised soil bacteria fix atmospheric nitrogen in return for carbon. However, ineffective strains can arise, making discrimination essential. Discrimination can occur via partner choice, where legumes prevent ineffective strains from entering, or via sanctioning, where plants provide fewer resources. Several studies have inferred that legumes exercise partner choice, but the rhizobia compared were not otherwise isogenic. To test when and how plants discriminate ineffective strains we developed sets of fixing and non-fixing strains that differed only in the expression of nifH - essential for nitrogen fixation - and could be visualised using marker genes. We show that the plant is unable to select against the non-fixing strain at the point of entry, but that non-fixing nodules are sanctioned. We also used the technique to characterise mixed nodules (containing both a fixing and a non-fixing strain), whose frequency could be predicted using a simple diffusion model. We discuss that sanctioning is likely to evolve in preference to partner choice in any symbiosis where partner quality cannot be adequately assessed until goods or services are actively exchanged

Awareness and Prevention of Aquatic Invasive Alien Species in the Iberian Peninsula by LIFE INVASAQUA: Midterm Outcomes

The Iberian society has a limited understanding of the threats posed by invasive alien species (IAS) in aquatic ecosystems. This lack of knowledge and awareness about IAS problems hampers any management policy proposed by public administration and stakeholders, contributing to missing an IAS management strategy. We present the midterm outcomes of the Environmental Governance and Information LIFE project—LIFE INVASAQUA—that will run between 2018 and 2023 in the Iberian Peninsula. The main goal of INVASQUA is to increase the Iberian public and stakeholders’ awareness of aquatic IAS problems and to develop tools that will improve an efficient early warning and rapid response (EWRR) framework for new IAS in freshwater and estuarine habitats in the Iberian Peninsula. We focus on new challenges and outcomes of the project to explore some of the problems and solutions encountered in the project implementation

CÓDIGOS DE CONDUCTA. COMERCIO ELECTRÓNICO DE FLORA Y FAUNA EXÓTICA INVASORA.

CÓDIGOS DE CONDUCTA. COMERCIO ELECTRÓNICO DE FLORA Y FAUNA EXÓTICA INVASORA