236 research outputs found

    Synchronization of the Frenet-Serret linear system with a chaotic nonlinear system by feedback of states

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    A synchronization procedure of the generalized type in the sense of Rulkov et al [Phys. Rev. E 51, 980 (1995)] is used to impose a nonlinear Malasoma chaotic motion on the Frenet-Serret system of vectors in the differential geometry of space curves. This could have applications to the mesoscopic motion of biological filamentsComment: 12 pages, 7 figures, accepted at Int. J. Theor. Phy

    Source identification for mobile devices, based on wavelet transforms combined with sensor imperfections

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    One of the most relevant applications of digital image forensics is to accurately identify the device used for taking a given set of images, a problem called source identification. This paper studies recent developments in the field and proposes the mixture of two techniques (Sensor Imperfections and Wavelet Transforms) to get better source identification of images generated with mobile devices. Our results show that Sensor Imperfections and Wavelet Transforms can jointly serve as good forensic features to help trace the source camera of images produced by mobile phones. Furthermore, the model proposed here can also determine with high precision both the brand and model of the device

    The Effects of an Adaptive and Distributed Transmission Power Control on the Performance of Energy Harvesting Sensor Networks

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    The design of routing protocols for wireless sensor networks (WSNs) has been traditionally tackled by assuming battery-powered sensors, in which minimizing the power consumption was the main objective. Advances in technology and the ability to harvest energy from the environment has enabled self-sustaining systems and thus diminish the significance of network lifetime considerations in the design of WSNs. Although WSNs operated by energy-harvesting sensors are not limited by network lifetime, they still pose new design challenges due to the unstable and uncertain amount of energy that can be harvested from the environment. In this paper, we propose a new protocol for energy-harvesting sensor networks that uses adaptive transmission power to maintain the network connectivity, and distributes the traffic load on the network. Based on local information, each node dynamically adjusts its transmission power in order to maximize the network’s end-to-end performance. The simulation results indicate that the proposed protocol keeps the network connected at most of the times by using an efficient power management, outperforming greedy forwarding and dynamic duty cycle protocols in terms of packet delivery ratio, delay, and power management

    Origin, distribution, and potential risk factors associated with influenza A virus in swine in two production systems in Guatemala

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    Background: Guatemala is the country with the largest swine production in Central America; however, evidence of influenza A virus (IAV) in pigs has not been clearly delineated. Objectives: In this study, we analyzed the presence and spatial distribution of IAV in commercial and backyard swine populations. Methods: Samples from two nationwide surveys conducted in 2010 and 2011 were tested using virological (rRT-PCR and virus isolation) and serological (ELISA and hemagglutination inhibition) assays to detect IAV. Results: Influenza A virus was detected in 15.7% of the sampled pigs (30.6% of herds) in 2010 and in 11.7% (24.2% of herds) in 2011. The percentage of seropositive pigs was 10.6% (16.1% of herds) and 1.4% (3.1% of herds) for each year, respectively. Three pandemic H1N1 and one seasonal human-like H3N2 viruses were isolated. Antibodies against viruses from different genetic clusters were detected. No reassortant strains with swine viruses were detected. The H3N2 virus was closely related to human viruses that circulated in Central America in 2010, distinct to the most recent human seasonal vaccine lineages. Spatial clusters of rRT-PCR positive herds were detected each year by scan statistics. Conclusions: Our results demonstrate circulation of IAV throughout Guatemala and identify commercial farms, animal health status, and age as potential risk factors associated with IAV infection and exposure. Detection of human-origin viruses in pigs suggests a role for humans in the molecular epidemiology of IAV in swine in Guatemala and evidences gaps in local animal and human surveillance

    Lethal Concentration of Carbonate OF Ca as a Function of the Osmotic Potential of the Solution in Sunflower (Heliantusannuus L.)

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    In order to know the effect of CaCO3 in solution, sunflower seedlings cv. Victoria, an experiment was completely randomized, where five concentrations of calcium carbonate were evaluated to determine the lethal concentration (LC50), pH and EC of the solution under laboratory conditions in the Universidad Tecnologica de Tehuacan, to simulate of excess Ca++ in the soils or nutrient solution. The results indicate, the LC50 was 62.8 mg CaCO3 L-1, so maximum values for pH, EC and calcium absorption, They were achieved at concentrations of 120 and 160 mg L-1 of CaCO3. This work can be concluded, Sunflower can absorb the high levels of calcium and used as an alternative, for remediation of agricultural soils affected hard water and Ca++ salts

    Response to Neutrons and Îł-rays of Two Liquid Scintillators

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    UltimaGoldTM AB and OptiphaseTrisafe are two liquid scintillators made by Perkin Elmer and EG & G Company respectively. Both are commercially promoted as scintillation detectors for α and β particles. In this work, the responses to γ-rays and neutrons of UltimaGoldTM AB and OptiphaseTriSafe liquid scintillators, without and with reflector, have been measured aiming to use these scintillators as γ-rays and neutron detectors. Responses to γ-rays and neutrons were measured as pulse shape spectra in a multichannel analyzer. Scintillators were exposed to gamma rays produced by 137Cs, 54Mn, 22Na and 60Co sources. The response to neutrons was obtained with a 241AmBe neutron source that was measured to 25 and 50 cm from the scintillators. The pulse height spectra due to gamma rays are shifted to larger channels as the photon energy increases and these responses are different from the response due to neutrons. Thus, UltimaGoldTM AB and OptiphaseTrisafe can be used to detect γ-rays and neutrons

    Multiple thermochronometers applied to the quantitative analysis of compressive systems: The southern sub-Andean fold and thrust belt of Bolivia: From source rock to trap

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    The evolution of fold and thrust belts requires time data restrictions to determine the rates related to the interaction of surface and subsurface processes and to quantify the time relationship between the components of the petroleum system: reservoir, seal, source rock and trap. The sub-Andean fold-and-thrust belt in the Bolivian territory in general, and the regional transect that links the structures of Curuyuqui-Carohuaicho-Tatarenda-Borebigua-Charagua and Mandeyapecua in particular, constitutes a complex multi-variable system in which the definition of time-Temperature (t-T) trajectories has led to new suitable structural and stratigraphic conclusions. The integration of multiple thermochronological-geochronological systems (Apatite Fission Track, Apatite (U-Th-Sm)/He and UPb SHRIMP on zircon) and the existing surface and subsurface geological constraints made it possible to develop a chrono-kinematic characterization of fault-related anticlines, defining their formation chronology, structural growth rate and link between them in the study area. Furthermore, it was also possible to perform a quantitative analysis of the subsidence-burial and exhumation-erosion phenomena that occurred from the deposition of Silurian-Devonian source rocks to the present time, providing relevant determinations to the modeling of the Oil & Gas system.Fil: Hernandez, Juan I.. Geomap S.a.; ArgentinaFil: Hernández, Roberto M.. Geomap S.a.; ArgentinaFil: Dalenz Farjat, Alejandra. Geomap S.a.; ArgentinaFil: Cristallini, Ernesto Osvaldo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Geología. Laboratorio de Modelado Geológico; ArgentinaFil: Alvarez, Luis A.. Geomap S.a.; ArgentinaFil: Dellmans, Luis M.. Geomap S.a.; ArgentinaFil: Costilla, Marcos Roberto. Geomap S.a.; ArgentinaFil: Alvarez, Andres F.. Geomap S.a.; ArgentinaFil: Becchio, Raul Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Bio y Geociencias del NOA. Universidad Nacional de Salta. Facultad de Ciencias Naturales. Museo de Ciencias Naturales. Instituto de Bio y Geociencias del NOA; ArgentinaFil: Bordese, Sofia. lA - Te Andes S.A. Laboratorio de Termocronología de Los Andes; ArgentinaFil: Arzadún, Guadalupe. lA - Te Andes S.A. Laboratorio de Termocronología de Los Andes; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Guibaldo, Cristina. lA - Te Andes S.A. Laboratorio de Termocronología de Los Andes; ArgentinaFil: Glasmacher, Ulrich A.. Ruprecht Karls Universitat Heidelberg; AlemaniaFil: Tomezzoli, Renata Nela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; ArgentinaFil: Stockli, Daniel F.. University of Texas; Estados UnidosFil: Fuentes, Facundo. YPF - Tecnología; ArgentinaFil: Soria Galvarro, Jaime. YPF - Tecnología; ArgentinaFil: Rosales, Adolfo. YPF - Tecnología; ArgentinaFil: Dzelalija, Francisco. YPF - Tecnología; ArgentinaFil: Haring, Claudio. YPF - Tecnología; Argentin
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