976 research outputs found

    Amplitude death in a ring of nonidentical nonlinear oscillators with unidirectional coupling

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    We study the collective behaviors in a ring of coupled nonidentical nonlinear oscillators with unidirectional coupling, of which natural frequencies are distributed in a random way. We find the amplitude death phenomena in the case of unidirectional couplings and discuss the differences between the cases of bidirectional and unidirectional couplings. There are three main differences; there exists neither partial amplitude death nor local clustering behavior but oblique line structure which represents directional signal flow on the spatio-temporal patterns in the unidirectional coupling case. The unidirectional coupling has the advantage of easily obtaining global amplitude death in a ring of coupled oscillators with randomly distributed natural frequency. Finally, we explain the results using the eigenvalue analysis of Jacobian matrix at the origin and also discuss the transition of dynamical behavior coming from connection structure as coupling strength increases.Comment: 14 pages, 11 figure

    Recent Advances in Unconventional Lithography for Challenging 3D Hierarchical Structures and Their Applications

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    In nanoscience and nanotechnology, nanofabrication is critical. Among the required processes for nanofabrication, lithography is one of core issues. Although conventional photolithography with recent remarkable improvement has contributed to the industry during the past few decades, fabrication of 3-dimensional (3D) nanostructure is still challenging. In this review, we summarize recent advances for the construction of 3D nanostructures by unconventional lithography and the combination of two top-down approaches or top-down and bottom-up approaches. We believe that the 3D hierarchical nanostructures described here will have a broad range of applications having adaptable levels of functional integration of precisely controlled nanoarchitectures that are required by not only academia, but also industry

    Recognition of the microbiota by Nod2 contributes to the oral adjuvant activity of cholera toxin through the induction of interleukin-1β

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    Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/152023/1/imm13105_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/152023/2/imm13105.pd

    Production Data Integration into High Resolution Geologic Models with Trajectory-based Methods and A Dual Scale Approach

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    Inverse problems associated with reservoir characterization are typically underdetermined and often have difficulties associated with stability and convergence of the solution. A common approach to address this issue is through the introduction of prior constraints, regularization or reparameterization to reduce the number of estimated parameters. We propose a dual scale approach to production data integration that relies on a combination of coarse-scale and fine-scale inversions while preserving the essential features of the geologic model. To begin with, we sequentially coarsen the fine-scale geological model by grouping layers in such a way that the heterogeneity measure of an appropriately defined 'static' property is minimized within the layers and maximized between the layers. Our coarsening algorithm results in a non-uniform coarsening of the geologic model with minimal loss of heterogeneity and the ?optimal? number of layers is determined based on a bias-variance trade-off criterion. The coarse-scale model is then updated using production data via a generalized travel time inversion. The coarse-scale inversion proceeds much faster compared to a direct fine-scale inversion because of the significantly reduced parameter space. Furthermore, the iterative minimization is much more effective because at the larger scales there are fewer local minima and those tend to be farther apart. At the end of the coarse-scale inversion, a fine-scale inversion may be carried out, if needed. This constitutes the outer iteration in the overall algorithm. The fine-scale inversion is carried out only if the data misfit is deemed to be unsatisfactory. We propose a fast and robust approach to calibrating geologic models by transient pressure data using a trajectory-based approach that based on a high frequency asymptotic expansion of the diffusivity equation. The trajectory or ray-based methods are routinely used in seismic tomography. In this work, we investigate seismic rays and compare them with streamlines. We then examine the applicability of streamline-based methods for transient pressure data inversion. Specifically, the high frequency asymptotic approach allows us to analytically compute the sensitivity of the pressure responses with respect to reservoir properties such as porosity and permeability. It facilitates a very efficient methodology for the integration of pressure data into geologic models

    Behavior of Connections Between SHS Columns & W-section Beams

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    Connections between SHS (Square Hollow Section) columns and W-section beams are generally fabricated by welding with or without endplates in the factory. These welded connections possess some finite degree of rotational stiffness which falls between fully rigid and ideally pinned joints. The influence of partially restrained connections on structural response not only changes the moment distribution but also increases frame drift. In this paper, a series of connection tests joining SHS column and W-section beam were executed and the test results compared with theoretical values. A method to utilize nonlinear moment-rotation relations of beam-to-column connections in steel framed structures is proposed. For the problem of contact in endplate-type connections, a simple and efficient method is also introduced

    Effects of Distilled Cervi Pantotrichum Cornu and Rehmannia glutinosa Pharmacopuncture at GB21 (Jianjing) on Heart Rate Variability: A Randomized and Double-blind Clinical Trial

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    AbstractBackground/PurposeThe purpose of this study was to use heart rate variability (HRV) to investigate the effects of distilled Cervi Pantotrichum Cornu pharmacopuncture and Rehmannia glutinosa pharmacopuncture on the autonomic nervous system.Materials and methodsForty healthy male participants were divided into two groups: the participants of the C-group received distilled Cervi Pantotrichum Cornu pharmacopuncture and those of the R-group received Rehmannia glutinosa pharmacopuncture. The study design was a randomized, double-blind clinical trial. Each participant received one of the two solutions injected at GB21 (Jianjing). The changes in HRV were measured seven times using the QECG-3: LXC3203 system (LAXTHA Inc. Korea). Time-dependent changes in HRV for each group were analyzed using the paired t test (significance level: p < 0.05), and the difference in the HRV fluctuations between the two experimental groups was evaluated using the independent sample test (significance level: p < 0.05).Results and conclusionThe results showed that Cervi Pantotrichum Cornu pharmacopuncture and Rehmannia glutinosa pharmacopuncture tended to activate the autonomic nervous system within the normal range. Cervi Pantotrichum Cornu pharmacopuncture tended to activate the sympathetic nervous system, whereas Rehmannia glutinosa pharmacopuncture tended to activate both the sympathetic and parasympathetic nervous systems

    Two-gap and paramagnetic pair-breaking effects on upper critical field of SmFeAsO0.85_{0.85} and SmFeAsO0.8_{0.8}F0.2_{0.2} single crystals

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    We investigated the temperature dependence of the upper critical field [Hc2(T)H_{c2}(T)] of fluorine-free SmFeAsO0.85_{0.85} and fluorine-doped SmFeAsO0.8_{0.8}F0.2_{0.2} single crystals by measuring the resistive transition in low static magnetic fields and in pulsed fields up to 60 T. Both crystals show that Hc2(T)H_{c2}(T)'s along the c axis [Hc2c(T)H_{c2}^c(T)] and in an abab-planar direction [Hc2ab(T)H_{c2}^{ab}(T)] exhibit a linear and a sublinear increase, respectively, with decreasing temperature below the superconducting transition. Hc2(T)H_{c2}(T)'s in both directions deviate from the conventional one-gap Werthamer-Helfand-Hohenberg theoretical prediction at low temperatures. A two-gap nature and the paramagnetic pair-breaking effect are shown to be responsible for the temperature-dependent behavior of Hc2cH_{c2}^c and Hc2abH_{c2}^{ab}, respectively.Comment: 21 pages, 8 figure

    Far-Ultraviolet Cooling Features of the Antlia Supernova Remnant

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    We present far-ultraviolet observations of the Antlia supernova remnant obtained with Far-ultraviolet IMaging Spectrograph (FIMS, also called SPEAR). The strongest lines observed are C IV 1548,1551 and C III 977. The C IV emission of this mixed-morphology supernova remnant shows a clumpy distribution, and the line intensity is nearly constant with radius. The C III 977 line, though too weak to be mapped over the whole remnant, is shown to vary radially. The line intensity peaks at about half the radius, and drops at the edge of the remnant. Both the clumpy distribution of C IV and the rise in the C IV to C III ratio towards the edge suggest that central emission is from evaporating cloudlets rather than thermal conduction in a more uniform, dense medium.Comment: 9 pages, 4 figures, will be published in ApJ December 1, 2007, v670n2 issue. see http://astro.snu.ac.kr/~jhshinn/ms.pd

    An Integration Avenue of Ground Monitoring Based on Wireless Sensor Networks

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    Since wireless sensor networks (WSNs) have a lot of potential capability to provide diverse services to human by monitoring things scattered in real world, they are envisioned as one of the core enabling technologies for ubiquitous computing which organizes and mediates both physical and social interactions anytime and anywhere. WSNs are being adopted in various fields and things in their zones are being monitored. However, existing WSNs are normally designed for observing special zones or regional things based on small-scale, low power, and short range technologies. Seamless system integration at a global scale is still in its infancy stage due to the lack of the fundamental integration technologies. In this paper, we present a global integration avenue of ground monitoring based on WSNs. The proposed avenue includes design, integration, and operational strategies of IP-WSN based territorial monitoring system to ensure compatibility, interoperability, and real-time. Specifically, we offer the standardization of sensing data formats using IP-WSN and database interfaces using EPC sensor network, which enable a spontaneous and systematic integration among the legacy WSN systems. Also, we categorize network topology according to topographic characteristics thereby helping deploy sensor nodes on the real environment. Therefore, the proposed technology would be a milestone for the practically deployable global territorial monitoring systems
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