Analytical properties of horizontal visibility graphs in the Feigenbaum scenario

Time series are proficiently converted into graphs via the horizontal visibility (HV) algorithm, which prompts interest in its capability for capturing the nature of different classes of series in a network context. We have recently shown [B. Luque et al., PLoS ONE 6, 9 (2011)] that dynamical systems can be studied from a novel perspective via the use of this method. Specifically, the period-doubling and band-splitting attractor cascades that characterize unimodal maps transform into families of graphs that turn out to be independent of map nonlinearity or other particulars. Here, we provide an in depth description of the HV treatment of the Feigenbaum scenario, together with analytical derivations that relate to the degree distributions, mean distances, clustering coefficients, etc., associated to the bifurcation cascades and their accumulation points. We describe how the resultant families of graphs can be framed into a renormalization group scheme in which fixed-point graphs reveal their scaling properties. These fixed points are then re-derived from an entropy optimization process defined for the graph sets, confirming a suggested connection between renormalization group and entropy optimization. Finally, we provide analytical and numerical results for the graph entropy and show that it emulates the Lyapunov exponent of the map independently of its sign.

Asymmetric propagation of airblast from bench blasting

This paper investigates the propagation of airblast from quarry blasting. Peak overpressure is calculated as a function of blasting parameters (explosive mass per delay and velocity at which the detonation sequence proceeds along the bench) and polar coordinates of the point of interest (distance to the blast and azimuth with respect to the free face of the blast). The model is in the form of the product of a classical scaled distance attenuation law times a directional correction factor. The latter considers the influence of the bench face, and attenuates overpressure at the top level and amplifies it at the bottom. Such factor also accounts for the effect of the delay by amplifying the pressure in the direction of the initiation sequence if the velocity of initiation exceeds half the speed of sound and up to an initiation velocity in the range of the speed of sound. The model has been fitted to an empirical data set composed by 134 airblast records monitored in 47 blasts at two quarries. The measurements were made at distances to the blast less than 450 m. The model is statistically significant and has a determination coefficient of 0.869

Occurrence and formation of indole-3-acetamide in Arabidopsis thaliana

An HPLC/GC–MS/MS technique (high-pressure liquid chromatography in combination with gas chromatography–tandem mass spectrometry) has been worked out to analyze indole-3-acetamide (IAM) with very high sensitivity, using isotopically labelled IAM as an internal standard. Using this technique, the occurrence of IAM in sterile-grown Arabidopsis thaliana (L.) Heynh. was demonstrated unequivocally. In comparison, plants grown under non-sterile conditions in soil in a greenhouse showed approximately 50% higher average levels of IAM, but the differences were not statistically significant. Thus, microbial contributions to the IAM extracted from the tissue are likely to be minor. Levels of IAM in sterile-grown seedlings were highest in imbibed seeds and then sharply declined during the first 24 h of germination and further during early seedling development to remain below 20–30 pmol g–1 fresh weight throughout the rosette stage. The decline in indole-3-aetic acid (IAA) levels during germination was paralleled by a similar decline in IAM levels. Recombinant nitrilase isoforms 1, 2 and 3, known to synthesize IAA from indole-3-acetonitrile, were shown to produce significant amounts of IAM in vitro as a second end product of the reaction besides IAA. NIT2 was earlier shown to be highly expressed in developing and in mature A. thaliana embryos, and NIT3 is the dominantly active gene in the hypocotyl and the cotyledons of young, germinating seedlings. Collectively, these data suggest that the elevated levels of IAM in seeds and germinating seedlings result from nitrilase action on indole-3-acetonitrile, a metabolite produced in the plants presumably from glucobrassicin turnover.

Characterization of ICT-based business models of social enterprises

In recent years new models for organizations working on overty alleviation have emerged. One of them, the social enterprise, has attracted the attention of both academics and practitioners all over the world. Even if defined in different ways depending on the context, social enterprise has an enormous potential to generate social benefits and to promote local agency and private initiative in poverty alleviation. In this sense, it is fitting to highlight the importance of identifying the main standards that permit the characterization of diverse social enterprises, in order to understand their main specificities and guarantee value generation for low-income populations. Another crucial factor is understanding innovation as a critical factor in promoting social enterprises. A powerful tool to enhance the impact and application of this model is Information and Communication Technologies. In the 21st century,these tools allow users to find new ways of collaboration, new sustainable business models and a cost-effective way of scaling-up initiatives. This paper, a product of the collaborative research between the Universidad Politécnica de Madrid and the Universidade Federal Fluminense, examines different business models for social enterprises and the role that ICT can play in scale and impact of these initiatives

Port planning for the Port of Vigo using port and city integration criteria

Project planning and architectural management of a port area should include many variables, it must be in harmony with its environment and its historical development as the key to successful integration. This article explains the elements which should be taken into account when doing such planning by describing the proposal presented on the ?Concurso public internacional de ideas para proyectar la ordenación urbanística y arquitectónica del área central del puerto de Vigo?, with the aim of sharing comprehensive applied design philosofy, it will inspire and help future designers. Creative imagination is great added value to engineering creations, but should not overwhelm functionality and sustainability, but to be in harmony with them. The maximum aesthetic expression in engineering is achieved as the product of the conceptual elegance of the functionality of the structures.

Quasiperiodic Graphs: Structural Design, Scaling and Entropic Properties

A novel class of graphs, here named quasiperiodic, are const ructed via application of the Horizontal Visibility algorithm to the time series generated along the quasiperiodic route to chaos. We show how the hierarchy of mode-locked regions represented by the Far ey tree is inherited by their associated graphs. We are able to establish, via Renormalization Group (RG) theory, the architecture of the quasiperiodic graphs produced by irrational winding numbers with pure periodic continued fraction. And finally, we demonstrate that the RG fixed-point degree distributions are recovered via optimization of a suitably defined graph entropy

Stability analysis of dam failures. Application to aurul tailing pond in Baia Mare (Romania)

La gestión de estériles de una explotación minera es un punto clave en el desarrollo económico de una actividad extractiva, y en especial, del entorno natural y social en el que se emplaza dicho proyecto. La minería de metales preciosos lleva asociada la construcción de balsas de residuos muy peligrosos, fruto de su proceso extractivo, como por ejemplo la cianuración en el caso del oro. Para un correcto funcionamiento de dichos emplazamientos es necesario escoger correctamente el método constructivo a partir de estudios de reconocimiento previos, como estudios de estabilidad geotécnica, contexto geológico de la zona, sismicidad, hidrología, etc. Así mismo, han de llevarse a cabo unas exhaustivas medidas de control y vigilancia para asegurar las condiciones de seguridad exigidas. La ruptura de la balsa de decantación de Aurul S.A. en Baia Mare (Rumania) el 30 de Enero del año 2000 ha sido escogido como caso de estudio de estabilidad de diques. ABSTRACT Tailing's management of a mining exploitation is a key point in the economical development of the extractive activity and, especially, of the natural and social environment of the site. Precious metals mining has high hazardous embankment construction associated, product of its extractive process, i.e. gold cyanidation. A correct operation of those sites makes necessary to choose a suitable construction method, based on previous studies as geotechnical stability studies, geological context of the area, seismicity, hydrology, etc. At the same time, exhaustive control and monitoring must be carried out in order to assure the required safety conditions. Aurul's decantation pond failure in Baia Mare (Romania), on 30th January 2000, has been chosen as a stability analysis case-study.

Quantifying dispersal paths in probabilistic habitat networks: a reply to hock and mumby (2015) and an overview of recent developments and applications

Hock and Mumby (2015) describe an approach to quantify dispersal probabilities along paths in networks of habitat patches. This approach basically consists in determining the most probable (most reliable) path for movement between habitat patches by calculating the product of the dispersal probabilities in each link (step) along the paths in the network. Although the paper by Hock and Mumby (2015) has value and includes interesting analyses (see comments in section 7 below), the approach they describe is not new.

Propellantless deorbiting of space debris by bare electrodynamic tethers : final report

A Space tether is a thin, multi-kilometers long conductive wire, joining a satellite and some opposite end mass, and keeping vertical in orbit by the gravity-gradient. The ambient plasma, being highly conductive, is equipotential in its own co-moving frame. In the tether frame, in relative motion however, there is in the plasma a motional electric field of order of 100 V/km, product of (near) orbital velocity and geomagnetic field. The electromotive force established over the tether length allows plasma contactor devices to collect electrons at one polarized-positive (anodic) end and eject electrons at the opposite end, setting up a current along a standard, fully insulated tether. The Lorentz force exerted on the current by the geomagnetic field itself is always drag; this relies on just thermodynamics, like air drag. The bare tether concept, introduced in 1992 at the Universidad Politécnica de Madrid (UPM), takes away the insulation and has electrons collected over the tether segment coming out polarized positive; the concept rests on 2D (Langmuir probe) current-collection in plasmas being greatly more efficient than 3D collection. A Plasma Contactor ejects electrons at the cathodic end. A bare tether with a thin-tape cross section has much greater perimeter and de-orbits much faster than a (corresponding) round bare tether of equal length and mass. Further, tethers being long and thin, they are prone to cuts by abundant small space debris, but BETs has shown that the tape has a probability of being cut per unit time smaller by more than one order of magnitude than the corresponding round tether (debris comparable to its width are much less abundant than debris comparable to the radius of the corresponding round tether). Also, the tape collects much more current, and de-orbits much faster, than a corresponding multi-line “tape” made of thin round wires cross-connected to survive debris cuts. Tethers use a dissipative mechanism quite different from air drag and can de-orbit in just a few months; also, tape tethers are much lighter than round tethers of equal length and perimeter, which can capture equal current. The 3 disparate tape dimensions allow easily scalable design. Switching the cathodic Contactor off-on allows maneuvering to avoid catastrophic collisions with big tracked debris. Lorentz braking is as reliable as air drag. Tethers are still reasonably effective at high inclinations, where the motional field is small, because the geomagnetic field is not just a dipole along the Earth polar axis. BETs is the EC FP7/Space Project 262972, financed in about 1.8 million euros, from 1 November 2010 to 31 January 2014, and carrying out RTD work on de-orbiting space debris. Coordinated by UPM, it has partners Università di Padova, ONERA-Toulouse, Colorado State University, SME Emxys, DLR–Bremen, and Fundación Tecnalia. BETs work involves 1) Designing, building, and ground-testing basic hardware subsystems Cathodic Plasma Contactor, Tether Deployment Mechanism, Power Control Module, and Tape with crosswise and lengthwise structure. 2) Testing current collection and verifying tether dynamical stability. 3) Preliminary design of tape dimensions for a generic mission, conducive to low system-to-satellite mass ratio and probability of cut by small debris, and ohmic-effects regime of tether current for fast de-orbiting. Reaching TRL 4-5, BETs appears ready for in-orbit demostration.

Closures of positive braids and the Morton-Franks-Williams inequality

We study the Morton-Franks-Williams inequality for closures of simple braids (also known as positive permutation braids). This allows to prove, in a simple way, that the set of simple braids is an orthonormal basis for the inner product of the Hecke algebra of the braid group defined by Kálmán, who first obtained this result by using an interesting connection with Contact Topology. We also introduce a new technique to study the Homflypt polynomial for closures of positive braids, namely resolution trees whose leaves are simple braids. In terms of these simple resolution trees, we characterize closed positive braids for which the Morton-Franks-Williams inequality is strict. In particular, we determine explicitly the positive braid words on three strands whose closures have braid index three.

Leslie Martin, Colin St. John Wilson y James Stirling : revisión de la modernidad en la arquitectura británica = Leslie Martin, Colin St. John Wilson and James Stirling : review of modernity in British architecture

La búsqueda de nuevas formas de modernidad se convirtió en la cuestión principal de la obras desarrolladas por Leslie Martin, Colin St. John Wilson y James Stirling entre los años 1955 y 1970. Enmarcadas dentro de la sensibilidad surgida en la posguerra británica, su profundo sentido crítico supone una renovada interpretación de alguno fundamentos del Movimiento Moderno así como la reflexión sobre la modificación y el uso de formas que tienen sus raíces en la tradición cultural. Esta investigación se estructura en cuatro temas ampliamente debatidos y que han articulado parte de la revisión moderna a lo largo de la segunda mitad del siglo XX: » la abstracción y el realismo » la revisión de la idea funcionalista » la reconsideración de los arquetipos formales » la relación entre forma y contexto urbano se muestran como base crítica para las obras seleccionadas. La tendencia hacia el realismo surgió como respuesta a la voluntad de universalidad (y objetividad) que representó el lenguaje abstracto, del mismo modo que la revisión de la idea funcionalista pretendió superar la consideración de la obra arquitectónica como producto racional de su función y tecnología. La reconsideración de los arquetipos de la tradición, a su vez, muestra una preocupación por el significado de las formas culturales del pasado, una cuestión igualmente decisiva en la renovada atención a la estructura de la ciudad histórica. Estos temas evidencian un interés por ampliar la arquitectura moderna sin que el reconocimiento de las formas del pasado suponga un distanciamiento respecto al futuro. La idea de revisión, asimismo, se convierte en estrategia a la hora de encontrar nuevas respuestas. Si algunos de los principios del Movimiento Moderno surgen como reacción al clasicismo Beaux Arts que le precedió, las propuestas analizadas muestran la validez operativa de este enfoque para crear obras de una intensa modernidad. Su interés, por lo tanto, no solo radica en su consideración como objetos de estudio que amplían nuestro conocimiento de un período determinado, sino como tradición reciente que sirve de base crítica para la práctica actual. ABSTRACT The search of new forms of modernity became the main theme of the works developed by Leslie Martin, Colin St. John Wilson and James Stirling between 1955 and 1970. Belonging to the sensitivity emerged in postwar Britain, their deep critical sense encourages a renewed interpretation of some principles of Modern Movement and a reflection about the modification or the use of forms that are rooted in cultural tradition. This research is divided into four themes widely discussed and which has articulated part of modern review along the second half of the twentieth century: » Abstraction and realism » Review of Functionalism » The reconsideration of the formal archetypes » The relationship between form and urban context are shown as critical base for the selected works. The trend toward realism arose in response to the will of universality (and objectivity) that represented the abstract language, just as the review of Functionalism aimed to overcome the consideration of architecture's work as rational product of its function and technology. The reconsideration of traditional archetypes, in turn, shows a concern for the meaning of the cultural forms, a matter equally decisive in the renewed attention to the structure of the historical city. These themes evidence an interest to extend modern architecture, without thereby the recognition of the past forms imply a distancing regarding the future. The idea of review also becomes strategy in finding new answers. If some principles of the Modern Movement arose in reaction to Beaux-Arts classicism which preceded it, the analyzed proposals show the operational validity of this approach to create works of a strong modernity. Their interest, therefore, lies not only in its consideration as study cases that broaden our knowledge of a certain period, but as a recent tradition which serves as a critic basis for the current practice.