1,767 research outputs found

    Synchronization in the presence of distributed delays

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    We study systems of identical coupled oscillators introducing a distribution of delay times in the coupling. For arbitrary network topologies, we show that the frequency and stability of the fully synchronized states depend only on the mean of the delay distribution. However, synchronization dynamics is sensitive to the shape of the distribution. In the presence of coupling delays, the synchronization rate can be maximal for a specific value of the coupling strength.Comment: 6 pages, 3 figure

    Theory of Bubble Nucleation and Cooperativity in DNA Melting

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    The onset of intermediate states (denaturation bubbles) and their role during the melting transition of DNA are studied using the Peyrard-Bishop-Daxuois model by Monte Carlo simulations with no adjustable parameters. Comparison is made with previously published experimental results finding excellent agreement. Melting curves, critical DNA segment length for stability of bubbles and the possibility of a two states transition are studied.Comment: 4 figures. Accepted for publication in Physical Review Letter

    Optimal cellular mobility for synchronization arising from the gradual recovery of intercellular interactions

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    Cell movement and intercellular signaling occur simultaneously during the development of tissues, but little is known about how movement affects signaling. Previous theoretical studies have shown that faster moving cells favor synchronization across a population of locally coupled genetic oscillators. An important assumption in these studies is that cells can immediately interact with their new neighbors after arriving at a new location. However, intercellular interactions in cellular systems may need some time to become fully established. How movement affects synchronization in this situation has not been examined. Here we develop a coupled phase oscillator model in which we consider cell movement and the gradual recovery of intercellular coupling experienced by a cell after movement, characterized by a moving rate and a coupling recovery rate respectively. We find (1) an optimal moving rate for synchronization, and (2) a critical moving rate above which achieving synchronization is not possible. These results indicate that the extent to which movement enhances synchrony is limited by a gradual recovery of coupling. These findings suggest that the ratio of time scales of movement and signaling recovery is critical for information transfer between moving cells.Comment: 18 single column pages + 1 table + 5 figures + Supporting Informatio

    Evaluation of the changes in working limits in an automobile assembly line using simulation

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    The aim of the work presented in this paper consists of the development of a decision-making support system, based on discrete-event simulation models, of an automobile assembly line which was implemented within an Arena simulation environment and focused at a very specific class of production lines with a four closed-loop network configuration. This layout system reflects one of the most common configurations of automobile assembly and preassembly lines formed by conveyors. The sum of the number of pallets on the intermediate buffers, remains constant, except for the fourth closed-loop, which depends on the four-door car ratio (x) implemented between the door disassembly and assembly stations of the car body. Some governing equations of the four closed-loops are not compatible with the capacities of several intermediate buffers for certain values of variable x. This incompatibility shows how the assembly line cannot operate in practice for x0,97 in a stationary regime, due to the starvation phenomenon or the failure of supply to the machines on the production line. We have evaluated the impact of the pallet numbers circulating on the first closed-loop on the performance of the production line, translated into the number of cars produced/hour, in order to improve the availability of the entire manufacturing system for any value of x. Until the present date, these facts have not been presented in specialized literature. © 2012 American Institute of Physics

    Impact of technological facilitators in the design and artisanal production processes. The Guarda Ninhos Project - craft and design of Gonçalo’s basketry

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    This research project analyses the impact of the use of prototyping and digital manufacturing tools in the development of new products based on the theme of Gonçalo's basketwork, in Guarda, Portugal [1]. Guarda Ninhos is an inclusive entrepreneurship project, the aim of which was to develop, produce and promote new local handicraft products. Solutions based on the socio-cultural, ecological and economic heritage of this region, knowledge immaterial heritage and expertise of their communities. Reinventing the culture of this place as a way of creating social and economic value, with the people who live there, was the followed line of action. Based on the results obtained, an attempt was made to outline forms of cooperation between this type of artisanal activities, with the most recent concepts of "industry 4.0" and industrial development methodologies - namely, (A) verifying the beneficial impact that the use of prototyping and digital fabrication tools can play in the design process of these products, optimising the development and production processes without jeopardising the premises that define the artisanal product; (B) contributing to the registration of ancestral knowledge and consolidation of artisanal processes and (C) showing how a strategic plan that aims to bring together and sustain the interdisciplinary artisan-designer relationship can be implemented.info:eu-repo/semantics/publishedVersio

    Calibración del número N de la curva de escurrimiento en una cuenca agropecuaria de 116 km2 de la provincia de Buenos Aires, Argentina

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    535-541In the mountainous area of Buenos Aires, Argentina, an increase in precipitation and in cultivated area has contributed to generating excessive runoff that has had severe impact on the region and on soil water erosion. The rain-runoff ratio in this region can help estimate the effects of floods. The local values of the runoff curve number (N) were calculated for the basin of the Arroyo Videla (Buenos Aires, Argentina), and its relationship to rainfall events was studied parting from daily rain data and runoff volumes. Values of 51 to 99 were obtained, and the most frequent were between 60 and 90. The relationship between N and precipitation exhibited a standard pattern that allowed adjusting an asymptotic value of 57. Rains less than 15 mm were associated with N between 85 and 90, while rains between 15 and 85 mm were related to N of 60 to 85. There was concordance between intermediate observed N and tabulated values of this parameter associated with each plant cover. This highlights the importance of obtaining local values of the studied variable to appropriately implement the method in basins of 100 km2

    Calibración del número N de la curva de escurrimiento en una cuenca agropecuaria de 116 km2 de la provincia de Buenos Aires, Argentina

    Get PDF
    535-541In the mountainous area of Buenos Aires, Argentina, an increase in precipitation and in cultivated area has contributed to generating excessive runoff that has had severe impact on the region and on soil water erosion. The rain-runoff ratio in this region can help estimate the effects of floods. The local values of the runoff curve number (N) were calculated for the basin of the Arroyo Videla (Buenos Aires, Argentina), and its relationship to rainfall events was studied parting from daily rain data and runoff volumes. Values of 51 to 99 were obtained, and the most frequent were between 60 and 90. The relationship between N and precipitation exhibited a standard pattern that allowed adjusting an asymptotic value of 57. Rains less than 15 mm were associated with N between 85 and 90, while rains between 15 and 85 mm were related to N of 60 to 85. There was concordance between intermediate observed N and tabulated values of this parameter associated with each plant cover. This highlights the importance of obtaining local values of the studied variable to appropriately implement the method in basins of 100 km2

    Thermodynamics of Extended Bodies in Special Relativity

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    Relativistic thermodynamics is generalized to accommodate four dimensional rotation in a flat spacetime. An extended body can be in equilibrium when its each element moves along a Killing flow. There are three types of basic Killing flows in a flat spacetime, each of which corresponds to translational motion, spatial rotation, and constant linear acceleration; spatial rotation and constant linear acceleration are regarded as four dimensional rotation. Translational motion has been mainly investigated in the past literature of relativistic thermodynamics. Thermodynamics of the other two is derived in the present paper.Comment: 8 pages, no figur

    Kinderanästhesie zur Protonenbestrahlung: Medizin fernab der Klinik

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    Zusammenfassung: Die Betreuung von Kleinkindern für die Protonentherapie stellt fachlich und menschlich hohe Anforderungen an das Anästhesieteam. Das Anästhesiepersonal soll in Kinderanästhesie speziell ausgebildet und erfahren sein, insbesondere da die Kinder sich oft in einem reduzierten Allgemeinzustand befinden. Die Infrastruktur soll gemäß den aktuellen anästhesiologischen Standards eingerichtet sein. Die ständige visuelle Überwachung des sedierten Patienten und das lückenlose Monitoring der Vitaldaten müssen gewährleistet sein. Propofol eignet sich ideal für die Sedierung von Kleinkindern in Spontanatmung für die Protonentherapie. Auch bei repetitiver Gabe über mehrere Wochen wird Propofol sehr gut toleriert. Eine enge Zusammenarbeit zwischen Radioonkologe, Onkologe und Anästhesist ist notwendig, um interkurrent auftretende medizinische Probleme optimal zu behandeln. Die besonderen Belange onkologischer Patienten müssen bei der Therapieplanung berücksichtigt werde
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