Existence of the Bogoliubov S(g) operator for the (:ϕ4:)2(:\phi^4:)_2 quantum field theory

We prove the existence of the Bogoliubov S(g) operator for the $(:\phi^4:)_2$ quantum field theory for coupling functions $g$ of compact support in space and time. The construction is nonperturbative and relies on a theorem of Kisy\'nski. It implies almost automatically the properties of unitarity and causality for disjoint supports in the time variable.Comment: LaTeX, 24 pages, minor modifications, typos correcte

Casimir force on a piston

We consider a massless scalar field obeying Dirichlet boundary conditions on the walls of a two-dimensional L x b rectangular box, divided by a movable partition (piston) into two compartments of dimensions a x b and (L-a) x b. We compute the Casimir force on the piston in the limit L -> infinity. Regardless of the value of a/b, the piston is attracted to the nearest end of the box. Asymptotic expressions for the Casimir force on the piston are derived for a << b and a >> b.Comment: 10 pages, 1 figure. Final version, accepted for publication in Phys. Rev.

Providing resilience to UAV swarms following planned missions

As we experience an unprecedented growth in the field of Unmanned Aerial Vehicles (UAVs), more and more applications keep arising due to the combination of low cost and flexibility provided by these flying devices, especially those of the multirrotor type. Within this field, solutions where several UAVs team-up to create a swarm are gaining momentum as they enable to perform more sophisticated tasks, or accelerate task execution compared to the single-UAV alternative. However, advanced solutions based on UAV swarms still lack significant advancements and validation in real environments to facilitate their adoption and deployment. In this paper we take a step ahead in this direction by proposing a solution that improves the resilience of swarm flights, focusing on handling the loss of the swarm leader, which is typically the most critical condition to be faced. Experiments using our UAV emulation tool (ArduSim) evidence the correctness of the protocol under adverse circumstances, and highlight that swarm members are able to seamlessly switch to an alternative leader when necessary, introducing a negligible delay in the process in most cases, while keeping this delay within a few seconds even in worst-case conditions

Bioecologia e sugestões para o Manejo da traça-dos-cachos em uva de vinho no Submédio do Vale do São Francisco.

bitstream/item/31860/1/Circular-Tecnica-93.pd

Computer simulations of VANETs using realistic city topologies

Researchers in vehicular ad hoc networks (VANETs) commonly use simulation to test new algorithms and techniques. This is the case because of the high cost and labor involved in deploying and testing vehicles in real outdoor scenarios. However, when determining the factors that should be taken into account in these simulations, some factors such as realistic road topologies and presence of obstacles are rarely addressed. In this paper, we first evaluate the packet error rate (PER) through actual measurements in an outdoor road scenario, and deduce a close model of the PER for VANETs. Secondly, we introduce a topology-based visibility scheme such that road dimension and geometry can be accounted for, in addition to line-of-sight. We then combine these factors to determine when warning messages (i.e., messages that warn drivers of danger and hazards) are successfully received in a VANET. Through extensive simulations using different road topologies, city maps, and visibility schemes, we show these factors can impact warning message dissemination time and packet delivery rate.This work was partially supported by the Ministerio de Educacion y Ciencia, Spain, under Grant TIN2011-27543-C03-01, and by the Diputacion General de Aragon, under Grant "subvenciones destinadas a la formacion y contratacion de personal investigador".Martínez, FJ.; Fogue, M.; Toh, C.; Cano Escribá, JC.; Tavares De Araujo Cesariny Calafate, CM.; Manzoni, P. (2013). Computer simulations of VANETs using realistic city topologies. Wireless Personal Communications. 69(2):639-663. https://doi.org/10.1007/s11277-012-0594-6S639663692Martinez F. J., Toh C.-K., Cano J.-C., Calafate C. T., Manzoni P. (2011) A survey and comparative study of simulators for vehicular ad hoc networks (VANETs). Wireless Communications and Mobile Computing Journal 11(7): 813–828Toh C.-K. (2001) Ad hoc mobile wireless networks: Protocols and systems. Prentice Hall, Englewood Cliffs, NJIEEE 802.11 Working Group. (2010). IEEE standard for information technology—telecommunications and information exchange between systems—local and metropolitan area networks—Specific requirements—Part 11: Wireless LAN medium access control (MAC) and physical layer (PHY) specifications amendment 6: Wireless Access in Vehicular Environments.Sommer, C., Eckhoff, D., German, R., & Dressler F. (2011). A computationally inexpensive empirical model of IEEE 802.11p radio shadowing in urban environments. In Eighth international conference on wireless on-demand network systems and services (WONS), pp. 84–90.Bohm, A., Lidstrom, K., Jonsson, M., & Larsson, T. (2010). Evaluating CALM M5-based vehicle-to-vehicle communication in various road settings through field trials. In Proceedings of the 35th IEEE conference on local computer networks (LCN’10), Denver, Colorado, USA, pp. 613–620.Martinez, F. J., Fogue, M., Coll, M., Cano, J.-C., Calafate, C. T., & Manzoni, P. (2010). Assessing the impact of a realistic radio propagation model on VANET scenarios using real maps. In 9th IEEE international symposium on network computing and applications (NCA), Boston, USA, pp. 132–139.Fall, K., & Varadhan, K. (2000). “ns notes and documents,” The VINT project. UC Berkeley, LBL, USC/ISI, and Xerox PARC, February 2000. Available at http://www.isi.edu/nsnam/ns/ns-documentation.html .Marinoni, S., & Kari, H. H. (2006). Ad hoc routing protocol performance in a realistic environment. In Proceedings of the international conference on networking, international conference on systems and international conference on mobile communications and learning technologies (ICN/ICONS/MCL 2006), Washington, DC, USA.Mahajan, A., Potnis, N., Gopalan, K., & Wang, A. (2007). Modeling VANET deployment in urban settings. In International workshop on modeling analysis and simulation of wireless and mobile systems (MSWiM 2007), Crete Island, Greece.Suriyapaiboonwattana, K., Pornavalai, C., & Chakraborty, G. (2009). An adaptive alert message dissemination protocol for VANET to improve road safety. In IEEE intlernational conference on fuzzy systems, 2009. FUZZ-IEEE 2009, pp. 1639–1644.Bako, B., Schoch, E., Kargl, F., & Weber, M. (2008). Optimized position based gossiping in VANETs. In Vehicular technology conference, 2008. VTC 2008-Fall. IEEE 68th, pp. 1–5.Martinez, F. J., Cano, J.-C., Calafate, C. T., & Manzoni, P. (2008). Citymob: A mobility model pattern generator for VANETs. In IEEE vehicular networks and applications workshop (Vehi-Mobi, held with ICC), Beijing, China.Torrent-Moreno, M., Santi, P., & Hartenstein, H. (2007). Inter-vehicle communications: Assessing information dissemination under safety constraints. In Proceedings of the 4th annual conference on wireless on demand network systems and services (WONS), Oberguyrgl, Austria.Martinez, F. J., Toh, C.-K., Cano, J.-C., Calafate, C. T., & Manzoni, P. (2009). Realistic radio propagation models (RPMs) for VANET simulations. In IEEE wireless communications and networking conference (WCNC), Budapest, Hungary.Martinez, F. J., Toh, C.-K., Cano, J.-C., Calafate, C. T., & Manzoni, P. (2010). A street broadcast reduction scheme (SBR) to mitigate the broadcast storm problem in VANETs. Wireless personal communications, pp. 1–14. doi: 10.1007/s11277-010-9989-4Ni, S.-Y., Tseng, Y.-C., Chen, Y.-S., & Sheu, J.-P. (1999). The broadcast storm problem in a mobile ad hoc network. In ACM/IEEE international conference on mobile computing and networking (MobiCom 1999), Seattle Washington.Krajzewicz, D., & Rossel, C. (2007). “Simulation of urban mobility (SUMO),” Centre for Applied Informatics (ZAIK) and the Institute of Transport Research at the German Aerospace Centre. Available at http://sumo.sourceforge.net/index.shtml .OpenStreetMap Team. (2009). OpenStreetMap, collaborative project to create a free editable map of the world. Available at http://www.openstreetmap.org .U.S. Census Bureau. (2009). TIGER, topologically integrated geographic encoding and referencing. Available at http://www.census.gov/geo/www/tiger .Krauss S., Wagner P., Gawron C. (1997) Metastable states in a microscopic model of traffic flow. Physical Review E 55(5): 5597–5602Krajzewicz, D., Hertkorn, G., Rossel, C., & Wagner, P. (2002). SUMO (Simulation of Urban MObility)—An open-source traffic simulation. In Proceedings of the 4th middle east symposium on simulation and modelling (MESM2002), Sharjah, United Arab Emirates, pp. 183–187

Diamagnetism of real-space pairs above Tc in hole doped cuprates

The nonlinear normal state diamagnetism reported by Lu Li et al. [Phys. Rev. B 81, 054510 (2010)] is shown to be incompatible with an acclaimed Cooper pairing and vortex liquid above the resistive critical temperature. Instead it is perfectly compatible with the normal state Landau diamagnetism of real-space composed bosons, which describes the nonlinear magnetization curves in less anisotropic cuprates La-Sr-Cu-O (LSCO) and Y-Ba-Cu-O (YBCO) as well as in strongly anisotropic bismuth-based cuprates in the whole range of available magnetic fields.Comment: 4 pages, 4 figure

The perseverance of Pacioli's goods inventory accounting system

This paper details sources of the 'undoubtedly strange' (Yamey, 1994a, p.119) system of goods inventory records described in Pacioli’s 1494 bookkeeping treatise and traces the longevity and widespread use of this early perpetual inventory recording (EPIR) system in English language texts. By doing so and contrasting this system with the bookkeeping treatment of modern texts, it is shown that the EPIR system persisted as the dominant form of goods inventory accounting for between 400 and 500 years and that the reasons for its demise are worthy of further consideration and research

Learning high-order interactions for polygenic risk prediction

Within the framework of precision medicine, the stratification of individual genetic susceptibility based on inherited DNA variation has paramount relevance. However, one of the most relevant pitfalls of traditional Polygenic Risk Scores (PRS) approaches is their inability to model complex high-order non-linear SNP-SNP interactions and their effect on the phenotype (e.g. epistasis). Indeed, they incur in a computational challenge as the number of possible interactions grows exponentially with the number of SNPs considered, affecting the statistical reliability of the model parameters as well. In this work, we address this issue by proposing a novel PRS approach, called High-order Interactions-aware Polygenic Risk Score (hiPRS), that incorporates high-order interactions in modeling polygenic risk. The latter combines an interaction search routine based on frequent itemsets mining and a novel interaction selection algorithm based on Mutual Information, to construct a simple and interpretable weighted model of user-specified dimensionality that can predict a given binary phenotype. Compared to traditional PRSs methods, hiPRS does not rely on GWAS summary statistics nor any external information. Moreover, hiPRS differs from Machine Learning-based approaches that can include complex interactions in that it provides a readable and interpretable model and it is able to control overfitting, even on small samples. In the present work we demonstrate through a comprehensive simulation study the superior performance of hiPRS w.r.t. state of the art methods, both in terms of scoring performance and interpretability of the resulting model. We also test hiPRS against small sample size, class imbalance and the presence of noise, showcasing its robustness to extreme experimental settings. Finally, we apply hiPRS to a case study on real data from DACHS cohort, defining an interaction-aware scoring model to predict mortality of stage II-III Colon-Rectal Cancer patients treated with oxaliplatin

A guided tour of asynchronous cellular automata

Research on asynchronous cellular automata has received a great amount of attention these last years and has turned to a thriving field. We survey the recent research that has been carried out on this topic and present a wide state of the art where computing and modelling issues are both represented.Comment: To appear in the Journal of Cellular Automat