Analysis of Round Off Errors with Reversibility Test as a Dynamical Indicator

We compare the divergence of orbits and the reversibility error for discrete time dynamical systems. These two quantities are used to explore the behavior of the global error induced by round off in the computation of orbits. The similarity of results found for any system we have analysed suggests the use of the reversibility error, whose computation is straightforward since it does not require the knowledge of the exact orbit, as a dynamical indicator. The statistics of fluctuations induced by round off for an ensemble of initial conditions has been compared with the results obtained in the case of random perturbations. Significant differences are observed in the case of regular orbits due to the correlations of round off error, whereas the results obtained for the chaotic case are nearly the same. Both the reversibility error and the orbit divergence computed for the same number of iterations on the whole phase space provide an insight on the local dynamical properties with a detail comparable with other dynamical indicators based on variational methods such as the finite time maximum Lyapunov characteristic exponent, the mean exponential growth factor of nearby orbits and the smaller alignment index. For 2D symplectic maps the differentiation between regular and chaotic regions is well full-filled. For 4D symplectic maps the structure of the resonance web as well as the nearby weakly chaotic regions are accurately described.Comment: International Journal of Bifurcation and Chaos, 201

Elliptic curves of large rank and small conductor

For r=6,7,...,11 we find an elliptic curve E/Q of rank at least r and the smallest conductor known, improving on the previous records by factors ranging from 1.0136 (for r=6) to over 100 (for r=10 and r=11). We describe our search methods, and tabulate, for each r=5,6,...,11, the five curves of lowest conductor, and (except for r=11) also the five of lowest absolute discriminant, that we found.Comment: 16 pages, including tables and one .eps figure; to appear in the Proceedings of ANTS-6 (June 2004, Burlington, VT). Revised somewhat after comments by J.Silverman on the previous draft, and again to get the correct page break

Topological insight into the non-Arrhenius mode hopping of semiconductor ring lasers

We investigate both theoretically and experimentally the stochastic switching between two counter-propagating lasing modes of a semiconductor ring laser. Experimentally, the residence time distribution cannot be described by a simple one parameter Arrhenius exponential law and reveals the presence of two different mode-hop scenarios with distinct time scales. In order to elucidate the origin of these two time scales, we propose a topological approach based on a two-dimensional dynamical system.Comment: 4 pages, 3 figure

HABITAT ASSOCIATIONS OF LAND BIRDS IN FERNANDO DE NORONHA, BRAZIL

ABSTRACT Fernando de Noronha is one of few archipelagos of Brazil. These islands harbor five species of land birds: two introduced species (House Sparrow, Passer domesticus, and Cattle Egret, Bubulcus ibis), one widespread dove (Eared Dove, Zenaida auriculata) and two endemic passerines. The two endemic species, Noronha Vireo (Vireo gracilirostris) and Noronha Elaenia (Elaenia ridleyana), have been classified as ‘Near Threatened’ and ‘Vulnerable’, respectively. Here, we quantified the abundance of land birds and correlated it to habitat features to assess potential habitat preferences. We carried out 120 five‐minute point counts in October 2009, and correlated bird abundance with percentages of woodland, bushes, low herbs, bare ground, and man‐made habitats in each sample. The abundance of Noronha Vireo and Noronha Elaenia was positively correlated with woodland and bushes cover. The Eared Dove was associated to sites with bare ground, the House Sparrow with man‐made habitats, and the Cattle Egret with low vegetation sites. Abundances of Noronha Vireo and Noronha Elaenia were significantly higher in sites with natural vegetation than in human‐influenced areas. The association between these species and areas with high native vegetation cover highlights their potential vulnerability to human disturbance. RESUMO ∙ Associações entre os ambientes e as aves terrestres de Fernando de Noronha, BrasilFernando de Noronha é um dos poucos arquipélagos do Brasil. Estas ilhas abrigam cinco espécies de aves terrestres: duas espécies introduzidas (Passer domesticus e Bubulcus ibis), uma pomba com ampla distribuição (Zenaida auriculata) e duas espécies de passeriformes endêmicos (Vireo gracilirostris e Elaenia ridleyana). Estas duas espécies são classificadas como “quase ameaçada” (V. gracilirostris) e “vulnerável” (E. ridleyana). Neste estudo, quantificamos a abundancia das aves terrestres e correlacionamos com as características de habitat do arquipélago de Fernando de Noronha. Fizemos 120 pontos de escuta de cinco minutos em outubro de 2009, comparamos a abundancia de aves com a porcentagem de ambientes contendo vegetação árvobórea, arbustos, vegetação rasteira, solo aberto e construções amostradas em um raio de 25m. A abundancia de V. gracilirostris e de E. ridleyana é positivamente correlacionada com porcentagem de cobertura de árvores e arbustos. A abundancia de Z. auriculata está positivamente correlacionada com a porcentagem de solo aberto, a abundancia de P. domesticus com construções e de B. ibis com a porcentagem de vegetação rasteira. As abundancias de V. gracilirostris e E. ridleyana são significativamente maiores em locais com vegetação conservada, distante das vilas. As associações entre as es

Popular Matchings in the Capacitated House Allocation Problem

We consider the problem of finding a popular matching in the Capacitated House Allocation problem (CHA). An instance of CHA involves a set of agents and a set of houses. Each agent has a preference list in which a subset of houses are ranked in strict order, and each house may be matched to a number of agents that must not exceed its capacity. A matching M is popular if there is no other matching M′ such that the number of agents who prefer their allocation in M′ to that in M exceeds the number of agents who prefer their allocation in M to that in M′. Here, we give an O(√C+n1m) algorithm to determine if an instance of CHA admits a popular matching, and if so, to find a largest such matching, where C is the total capacity of the houses, n1 is the number of agents and m is the total length of the agents’ preference lists. For the case where preference lists may contain ties, we give an O(√Cn1+m) algorithm for the analogous problem

Effect of pore generator on microstructure and resistivity of Sb2O3 and CuO doped SnO2 electrodes

[EN] Sb(2)O(3)and CuO doped SnO(2)ceramic electrodes could be an alternative to the ones currently used ones in the electrooxidation process of water pollutants. The rise of electrode surface by introducing a porogen agent on the composition was analysed in order to increase the electrochemical active surface. For this reason, several substances were tested. Although the densification and total pore volume had similar values, the microstructures and the pore size distributions generated were strongly dependent on porogen nature. A total of five porogens were tested, but petroleum coke turned out to be the best option for these electrodes. It was found that the electrical resistivity depends on the nature of pore generator. Furthermore, its relation to the porosity can be modelled with Archie's or Pabst's equations.The authors are very grateful to the Ministerio de Economia y Competitividad (Projects: CTQ2015-65202-C2-1-R and CTQ2015-65202-C2-2-R) and to the European Regional Development Fund (FEDER), for their economic support.Sánchez-Rivera, M.; Gozalbo, A.; Pérez-Herranz, V.; Mestre, S. (2020). Effect of pore generator on microstructure and resistivity of Sb2O3 and CuO doped SnO2 electrodes. Journal of Porous Materials. 27(6):1801-1808. https://doi.org/10.1007/s10934-020-00959-0S18011808276C.A. Martínez-Huitle, S. Ferro, Electrochemical oxidation of organic pollutants for the wastewater treatment: direct and indirect processes. Chem. Soc. Rev. 35, 1324–1340 (2006). https://doi.org/10.1039/B517632HC.A. Kent, J.J. Concepcion, C.J. Dares, D.A. Torelli, A.J. Rieth, A.S. Miller, P.G. Hoertz, T.J. Meyer, Water oxidation and oxygen monitoring by cobalt-modified fluorine-doped tin oxide electrodes. J. Am. Chem. Soc. 135, 8432–8435 (2013). https://doi.org/10.1021/ja400616aM.P. Miranda, R. Del Rio, M.A. Del Valle, M. Faundez, F. Armijo, Use of fluorine-doped tin oxide electrodes for lipoic acid determination in dietary supplements. J. Electroanal. Chem. 668, 1–6 (2012). https://doi.org/10.1016/j.jelechem.2011.12.022M.A.Q. Alfaro, S. Ferro, C.A. Martínez-Huitle, Y.M. Vong, Boron doped diamond electrode for the wastewater treatment. J. Braz. Chem. Soc. 17, 227–236 (2006). https://doi.org/10.1590/S0103-50532006000200003J. Mora-Gómez, M. García-Gabaldón, E. Ortega, M.-J. Sánchez-Rivera, S. Mestre, V. Pérez-Herranz, Evaluation of new ceramic electrodes based on Sb-doped SnO2 for the removal of emerging compounds present in wastewater. Ceram. Int. 44, 2216–2222 (2018). https://doi.org/10.1016/j.ceramint.2017.10.178C.J. Evans, Industrial uses of tin chemicals, Chem. Tin, Springer Netherlands, Dordrecht, 1998: pp. 442–479. https://doi.org/10.1007/978-94-011-4938-9_12J. Molera, T. Pradell, N. Salvadó, M. Vendrell-Saz, Evidence of tin oxide recrystallization in opacified lead glazes. J. Am. Ceram. Soc. 82, 2871–2875 (2004). https://doi.org/10.1111/j.1151-2916.1999.tb02170.xP.P. Tsai, I.-C. Chen, M.H. Tzeng, Tin oxide (SnOX) carbon monoxide sensor fabricated by thick-film methods. Sensors Actuators B 25, 537–539 (1995). https://doi.org/10.1016/0925-4005(95)85116-XF. Li, J. Xu, X. Yu, L. Chen, J. Zhu, Z. Yang, X. Xin, One-step solid-state reaction synthesis and gas sensing property of tin oxide nanoparticles. Sensors Actuators B 165–169. http://www.sciencedirect.com/science/article/pii/S0925400501009479S. Zuca, M. Terzi, M. Zaharescu, K. Matiasovsky, Contribution to the study of SnO2-based ceramics. J. Mater. Sci. 26, 1673–1676 (1991). https://doi.org/10.1007/BF00544681M. BATZILL, U. DIEBOLD, The surface and materials science of tin oxide. Prog. Surf. Sci. 79, 47–154 (2005). https://doi.org/10.1016/j.progsurf.2005.09.002G. Monrós. El color de la cerámica: nuevos mecanismos en pigmentos para los nuevos procesados de la industria cerámica, n.d. https://books.google.es/books/about/El_Color_de_la_cerámica.html?id=yfIogcGvdqUC&redir_esc=y . Accessed 29 Aug 2018E.R. Leite, J.A. Cerri, E. Longo, J.A. Varela, C.A. Paskocima, Sintering of ultrafine undoped SnO2 powder. J. Eur. Ceram. Soc. 21, 669–675 (2001). https://doi.org/10.1016/S0955-2219(00)00250-8S. Mihaiu, O. Scarlat, G. Aldica, M. Zaharescu, SnO2 electroceramics with various additives. J. Eur. Ceram. Soc. 21, 1801–1804 (2001). https://doi.org/10.1016/S0955-2219(01)00119-4C.R. Foschini, L. Perazolli, J.A. Varela, Sintering of tin oxide using zinc oxide as a densification aid. J. Mater. Sci. 39, 5825–5830 (2004). https://doi.org/10.1023/B:JMSC.0000040095.03906.61M.S. Castro, C.M. Aldao, Characterization of SnO2-varistors with different additives. J. Eur. Ceram. Soc. 18, 2233–2239 (1998). https://doi.org/10.1016/S0955-2219(97)00130-1A.-M. Popescu, S. Mihaiu, S. Zuca, Microstructure and electrochemical behaviour of some SnO2-based inert electrodes in aluminium electrolysis. Zeitschrift Für Naturforsch. A 57, 71–75 (2002). https://doi.org/10.1515/zna-2002-1-210M.R. Sahar, M. Hasbullah, Properties of SnO2-based ceramics. 30, 5304–5305 (1995)D. Nisiro, G. Fabbri, G.C. Celotti, A. Bellosi, Influence of the additives and processing conditions on the characteristics of dense SnO2-based ceramics. J. Mater. Sci. 38, 2727–2742 (2003). https://doi.org/10.1023/A:1024459307992M.-J. Sánchez-Rivera, CuO improved (Sn,Sb)O2 ceramic anodes for electrochemical advanced oxidation processes. Int. J. Appl. Ceram. Technol. (2018)B. Das, B. Chakrabarty, P. Barkakati, Preparation and characterization of novel ceramic membranes for micro-filtration applications. Ceram. Int. 42, 14326–14333 (2016). https://doi.org/10.1016/j.ceramint.2016.06.125I. Hedfi, N. Hamdi, M.A. Rodriguez, E. 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Quantum Electrodynamics at Extremely Small Distances

The asymptotics of the Gell-Mann - Low function in QED can be determined exactly, \beta(g)= g at g\to\infty, where g=e^2 is the running fine structure constant. It solves the problem of pure QED at small distances L and gives the behavior g\sim L^{-2}.Comment: Latex, 6 pages, 1 figure include

Long term effectiveness of electrochemotherapy for the treatment of lower lip squamous cell carcinoma

Purpose: Electrochemotherapy (ECT) is a therapeutic approach based on the local application of electrical pulses that permeabilize cell membranes to enhance the uptake of low-permeant chemotherapeutic agents, thus increasing their cytotoxic effects. Materials and Methods: Twenty-one patients with SCC of the lower lip were treated according to the European Standard Operating Procedures of Electrochemotherapy. Bleomycin (15,000 IU/m2 body surface area) was administered intravenously over a 1-minute period. Eight electrical pulses (amplitude, 1000 V/cm; duration, 100 μs) were generated and delivered at a repetition frequency of 5 kHz. Changes in tumor volume were used to assess treatment response. Results: Objective response (OR), complete response (CR), and partial response (PR) rates of 100%, 71.4%, and 28.6% respectively were demonstrated following a single session of ECT. ECT was well tolerated, and no adverse events occurred. Conclusions: Intravenous bleomycin-based ECT is a safe and effective therapy for SCC of the lower lip. ECT improves the quality-of-life of patients by preserving the function and the aesthetic appearance of the affected area. ECT provides a therapeutic option for elderly and frail patients who, due to their state of health, are not suitable for, or refuse surgical interventions

A comparative and exploratory study of toy products in the circular economy

This paper concerns relatively unexplored research concerning the environmental impact of children's toys. This segment represents a challenge in the circular economy, a priority area concerned with the EU´s ambition of drastically reducing the use of petroleum-based plastics in Europe, along with the optimisation of waste as valuable resources for design. The paper discusses the methodological approaches used in an ongoing explorative study analysis of sixteen toy product cases through empirical research concerning the life cycle impact, and specifically, the end of life implications of children's toys, focusing on eight distinct toy categories spanning an age range of six months to eight years old. A mixed methods approach was used, with three distinct stages: Individual component level life cycle analysis, the use of Circular Product Design assessment and improvement tools, and semi-structured interviews of three key stakeholders to evaluate the toys, complemented by the analysis of the economic depreciation of the toy's value. Following this analysis, designers sought to improve the circularity of the products using one of four circular product design approaches, designing for: "slowing the loop", "closing the loop", "bio-based loop" or "bio-inspired loop" (Mestre and Cooper, 2017). The preliminary findings of the research show that higher value branded items significantly outperformed their less expensive counterparts in both the LCA and stakeholder research, due to higher value and their recognition in the second hand market leading to 2 nd or 3 rd lives, slowing the loop. Opportunities for improvement were identified to further improve toy circularity and close the loops through enhanced product attachment and circular business opportunities. Opportunities for bio-based solutions were also identified for lower value products, linking lower cost and shorter intended life to bio-based solutions, particularly in the craft and outdoor toys examples