A method to discern complexity in two-dimensional patterns generated by coupled map lattices

Complex patterns generated by the time evolution of a one-dimensional digitalized coupled map lattice are quantitatively analyzed. A method for discerning complexity among the different patterns is implemented. The quantitative results indicate two zones in parameter space where the dynamics shows the most complex patterns. These zones are located on the two edges of an absorbent region where the system displays spatio-temporal intermittency.Comment: 3 pages, 3 figures; some information about the authors: http://add.unizar.es/public/100_16613/index.htm

The observable effects of a photospheric component on GRB's and XRF's prompt emission spectrum

A thermal radiative component is likely to accompany the first stages of the prompt emission of Gamma-ray bursts (GRB's) and X-ray flashes (XRF's). We analyze the effect of such a component on the observable spectrum, assuming that the observable effects are due to a dissipation process occurring below or near the thermal photosphere. We consider both the internal shock model and a 'slow heating' model as possible dissipation mechanisms. For comparable energy densities in the thermal and the leptonic component, the dominant emission mechanism is Compton scattering. This leads to a nearly flat energy spectrum (\nu F_\nu \propto \nu^0) above the thermal peak at ~10-100 keV and below 10-100 MeV, for a wide range of optical depths 0.03 <~ \tau_{\gamma e} <~ 100, regardless of the details of the dissipation mechanism or the strength of the magnetic field. At lower energies steep slopes are expected, while above 100 MeV the spectrum depends on the details of the dissipation process. For higher values of the optical depth, a Wien peak is formed at 100 keV - 1 MeV, and no higher energy component exists. For any value of \tau_{\gamma e}, the number of pairs produced does not exceed the baryon related electrons by a factor larger than a few. We conclude that dissipation near the thermal photosphere can naturally explain both the steep slopes observed at low energies and a flat spectrum above 10 keV, thus providing an alternative scenario to the optically thin synchrotron - SSC model.Comment: Discussion added on the results of Baring & Braby (2004); Accepted for publication in Ap.

Binary frequency of planet-host stars at wide separations: A new brown dwarf companion to a planet-host star

The aim of the project is to improve our knowledge on the multiplicity of planet-host stars at wide physical separations. We cross-matched approximately 6200 square degree area of the Southern sky imaged by the Visible Infrared Survey Telescope for Astronomy (VISTA) Hemisphere Survey (VHS) with the Two Micron All Sky Survey (2MASS) to look for wide common proper motion companions to known planet-host stars. We complemented our astrometric search with photometric criteria. We confirmed spectroscopically the co-moving nature of seven sources out of 16 companion candidates and discarded eight, while the remaining one stays as a candidate. Among these new wide companions to planet-host stars, we discovered a T4.5 dwarf companion at 6.3 arcmin (~9000 au) from HIP70849, a K7V star which hosts a 9 Jupiter mass planet with an eccentric orbit. We also report two new stellar M dwarf companions to one G and one metal-rich K star. We infer stellar and substellar binary frequencies for our complete sample of 37 targets of 5.4+/-3.8% and 2.7+/-2.7% (1 sigma confidence level), respectively, for projected physical separations larger than ~60-160 au assuming the range of distances of planet-host stars (24-75 pc). These values are comparable to the frequencies of non planet-host stars. We find that the period-eccentricity trend holds with a lack of multiple systems with planets at large eccentricities (e > 0.2) for periods less than 40 days. However, the lack of planets more massive than 2.5 Jupiter masses and short periods (<40 days) orbiting single stars is not so obvious due to recent discoveries by ground-based transit surveys and space missions.Comment: Accepted for publication in A&A, 13 pages, 5 figures, 3 tables, optical spectra will be available at CDS Strasbour

An Effective Temperature Scale for Late M and L Dwarfs, from Resonance Absorption Lines of CsI and RbI

We present Keck HIRES spectra of 6 late-M dwarfs and 11 L dwarfs. Our goal is to assign effective temperatures to the objects using detailed atmospheric models and fine analysis of the alkali resonance absorption lines of CsI and RbI. These yield mutually consistent results (+-150 K) when we use ``cleared-dust'' models, which account for the removal of refractory species from the molecular states but do not include dust opacities. We find a tendency for the RbI line to imply a slightly higher temperature, which we ascribe to an incomplete treatment of the overlying molecular opacities. The final effective temperatures we adopt are based on the CsI fits alone, though the RbI fits support the CsI temperature sequence. This work, in combination with results from the infrared, hints that dust in these atmospheres has settled out of the high atmosphere but is present in the deep photosphere. We also derive radial and rotational velocities for all the objects, finding that the previously discovered trend of rapid rotation for very low mass objects is quite pervasive. To improve on our analysis, there is a clear need for better molecular line lists and a more detailed understanding of dust formation and dynamics.Comment: 53 pages, including 20 figures and 2 Tables; accepted in Ap

On the variability of HD 170699 - a possible COROT target

We present the analysis of the variability of HD 170699, a COROT star showing the characteristics of a non evolutionary Delta Scuti star with high rotational velocity. There is a clear period of 10.45 c/d with 5.29 mmag amplitude in the y filter. From the data, it can be seen that the star shows multi-periodicity and it is necessary to add more frequencies to adjust the observationsComment: To appear in RevMexAA(SC) in Proceedings of XII Reunion Regional Latinoamericana de la UAI held in Isla Margarita, Venezuela, October 22-26, 200

Two independent S-phase checkpoints regulate appressorium-mediated plant infection by the rice blast fungus Magnaporthe oryzae

To cause rice blast disease, the fungal pathogen Magnaporthe oryzae develops a specialized infection structure called an appressorium. This dome-shaped, melanin-pigmented cell generates enormous turgor and applies physical force to rupture the rice leaf cuticle using a rigid penetration peg. Appressorium-mediated infection requires septin-dependent reorientation of the F-actin cytoskeleton at the base of the infection cell, which organizes polarity determinants necessary for plant cell invasion. Here, we show that plant infection by M. oryzae requires two independent S-phase cell-cycle checkpoints. Initial formation of appressoria on the rice leaf surface requires an S-phase checkpoint that acts through the DNA damage response (DDR) pathway, involving the Cds1 kinase. By contrast, appressorium repolarization involves a novel, DDR-independent S-phase checkpoint, triggered by appressorium turgor generation and melanization. This second checkpoint specifically regulates septin- dependent, NADPH oxidase-regulated F-actin dynamics to organize the appressorium pore and facilitate entry of the fungus into host tissue

Safety and Security Co-engineering and Argumentation Framework

Automotive systems become increasingly complex due to their functional range and data exchange with the outside world. Until now, functional safety of such safety-critical electrical/electronic systems has been covered successfully. However, the data exchange requires interconnection across trusted boundaries of the vehicle. This leads to security issues like hacking and malicious attacks against interfaces, which could bring up new types of safety issues. Before mass-production of automotive systems, arguments supported by evidences are required regarding safety and security. Product engineering must be compliant to specific standards and must support arguments that the system is free of unreasonable risks. This paper shows a safety and security co-engineering framework, which covers standard compliant process derivation and management, and supports product specific safety and security co-analysis. Furthermore, we investigate process- and product-related argumentation and apply the approach to an automotive use case regarding safety and security.This work is supported by the projects EMC2 and AMASS. Research leading to these results has received funding from the EU ARTEMIS Joint Undertaking under grant agreement no. 621429 (project EMC2), project AMASS (H2020-ECSEL no 692474; Spain’s MINECO ref. PCIN-2015-262) and from the COMET K2 - Competence Centres for Excellent Technologies Programme of the Austrian Federal Ministry for Transport, Innovation and Technology (bmvit), the Austrian Federal Ministry of Science, Research and Economy (bmwfw), the Austrian Research Promotion Agency (FFG), the Province of Styria and the Styrian Business Promotion Agency (SFG)