547 research outputs found

    FPGA Implementation of a Frame Synchronization Algorithm for Powerline Communications

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    This paper presents an FPGA implementation of a pilot–based time synchronization scheme employing orthogonal frequency division multiplexing for powerline communication channels. The functionality of the algorithm is analyzed and tested over a real powerline residential network. For this purpose, an appropriate transmitter circuit, implemented by an FPGA, and suitable coupling circuits are constructed. The system has been developed using VHDL language on Nallatech XtremeDSP development kits. The communication system operates in the baseband up to 30 MHz. Measurements of the algorithm's good performance in terms of the number of detected frames and timing offset error are taken and compared to simulations of existing algorithms

    The Grover algorithm with large nuclear spins in semiconductors

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    We show a possible way to implement the Grover algorithm in large nuclear spins 1/2<I<9/2 in semiconductors. The Grover sequence is performed by means of multiphoton transitions that distribute the spin amplitude between the nuclear spin states. They are distinguishable due to the quadrupolar splitting, which makes the nuclear spin levels non-equidistant. We introduce a generalized rotating frame for an effective Hamiltonian that governs the non-perturbative time evolution of the nuclear spin states for arbitrary spin lengths I. The larger the quadrupolar splitting, the better the agreement between our approximative method using the generalized rotating frame and exact numerical calculations.Comment: 11 pages, 18 EPS figures, REVTe

    Multiscale Hy3S: Hybrid stochastic simulation for supercomputers

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    BACKGROUND: Stochastic simulation has become a useful tool to both study natural biological systems and design new synthetic ones. By capturing the intrinsic molecular fluctuations of "small" systems, these simulations produce a more accurate picture of single cell dynamics, including interesting phenomena missed by deterministic methods, such as noise-induced oscillations and transitions between stable states. However, the computational cost of the original stochastic simulation algorithm can be high, motivating the use of hybrid stochastic methods. Hybrid stochastic methods partition the system into multiple subsets and describe each subset as a different representation, such as a jump Markov, Poisson, continuous Markov, or deterministic process. By applying valid approximations and self-consistently merging disparate descriptions, a method can be considerably faster, while retaining accuracy. In this paper, we describe Hy3S, a collection of multiscale simulation programs. RESULTS: Building on our previous work on developing novel hybrid stochastic algorithms, we have created the Hy3S software package to enable scientists and engineers to both study and design extremely large well-mixed biological systems with many thousands of reactions and chemical species. We have added adaptive stochastic numerical integrators to permit the robust simulation of dynamically stiff biological systems. In addition, Hy3S has many useful features, including embarrassingly parallelized simulations with MPI; special discrete events, such as transcriptional and translation elongation and cell division; mid-simulation perturbations in both the number of molecules of species and reaction kinetic parameters; combinatorial variation of both initial conditions and kinetic parameters to enable sensitivity analysis; use of NetCDF optimized binary format to quickly read and write large datasets; and a simple graphical user interface, written in Matlab, to help users create biological systems and analyze data. We demonstrate the accuracy and efficiency of Hy3S with examples, including a large-scale system benchmark and a complex bistable biochemical network with positive feedback. The software itself is open-sourced under the GPL license and is modular, allowing users to modify it for their own purposes. CONCLUSION: Hy3S is a powerful suite of simulation programs for simulating the stochastic dynamics of networks of biochemical reactions. Its first public version enables computational biologists to more efficiently investigate the dynamics of realistic biological systems

    Optimized stray-field-induced enhancement of the electron spin precession by buried Fe gates

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    The magnetic stray field from Fe gates is used to modify the spin precession frequency of InGaAs/GaAs quantum-well electrons in an external magnetic field. By using an etching process to position the gates directly in the plane of the quantum well, the stray-field influence on the spin precession increases significantly compared with results from previous studies with top-gated structures. In line with numerical simulations, the stray-field-induced precession frequency increases as the gap between the ferromagnetic gates is reduced. The inhomogeneous stray field leads to additional spin dephasing.Comment: 4 pages, 2 figure

    Model-Driven Designs of an Oscillating Gene Network

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    ABSTRACT The current rapid expansion of biological knowledge offers a great opportunity to rationally engineer biological systems that respond to signals such as light and chemical inducers by producing specific proteins. Turning on and off the production of proteins on demand holds great promise for creating significant biotechnological and biomedical applications. With successful stories already registered, the challenge still lies with rationally engineering gene regulatory networks which, like electronic circuits, sense inputs and generate desired outputs. From the literature, we have found kinetic and thermodynamic information describing the molecular components and interactions of the transcriptionally repressing lac, tet, and ara operons. Connecting these components in a model gene network, we determine how to change the kinetic parameters to make this normally nonperiodic system one which has well-defined oscillations. Simulating the designed lac-tet-ara gene network using a hybrid stochastic-discrete and stochastic-continuous algorithm, we seek to elucidate the relationship between the strength and type of specific connections in the gene network and the oscillatory nature of the protein product. Modeling the molecular components of the gene network allows the simulation to capture the dynamics of the real biological system. Analyzing the effect of modifications at this level provides the ability to predict how changes to experimental systems will alter the network behavior, while saving the time and expense of trial and error experimental modifications

    Kajian Sifat Fisik, Kimia Dan Sensoris Bubur Bayi Instan Berbahan Dasar Tepung Tempe Koro Glinding (Phaseolus Lunatus), Tepung Beras Merah (Oryza Nivara) Dan Tepung Labu Kuning (Cucurbita Moschata)

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    Makanan pendamping ASI adalah makanan yang diberikan disamping ASI kepada bayi berusia 6 bulan keatas untukmemenuhi kebutuhan gizinya. Tujuan dari penelitian ini adalah mendapatkan formula bubur bayi instan yang sesuai dengan syaratmutu MP-ASI instan SNI 01.7111.1 (2005). Hasil pengujian sifat kimia menunjukkan bahwa penambahan tepung tempe koroglinding dapat meningkatkan kadar lemak dan total kalori tetapi menurunkan kadar karbohidrat dan kadar betakaroten. Hasilpengujian sifat fisik menunjukkan bahwa penambahan tepung tempe koro glinding dapat meningkatkan densitas kamba danmenurunkan daya serap air. Hasil pengujian sensoris menunjukkan penambahan tepung tempe koro glinding paling banyak, palingdisukai panelis. Variasi formula tidak memberikan perbedaan yang signifikan pada kadar air, kadar abu, kadar protein dan kelarutananatar sampel. Keseluruhan hasil analisis menunjukan bubur bayi instan F1,F2 dan F3 sudah sesuai SNI .7111.1 (2005) meskipuntotal kalori metode bomb calorimeter belum memenuhi persyaratan SNI.7111.1 (2005)

    TakeCARE, a Video to Promote Bystander Behavior on College Campuses: Replication and Extension

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    Previous research has demonstrated that college students who view TakeCARE, a video bystander program designed to encourage students to take action to prevent sexual and relationship violence (i.e., bystander behavior), display more bystander behavior relative to students who view a control video. The current study aimed to replicate and extend these findings by testing two different methods of administering TakeCARE and examining moderators of TakeCARE’s effects on bystander behavior. Students at four universities (n = 557) were randomly assigned to one of three conditions: (a) view TakeCARE in a monitored computer lab, (b) view TakeCARE at their own convenience after receiving an email link to the video, or (c) view a video about study skills (control group). Participants completed measures of bystander behavior at baseline and at a 1-month follow-up. Participants in both TakeCARE conditions reported more bystander behavior at follow-up assessments, compared with participants in the control condition. The beneficial effect of TakeCARE did not differ significantly across administration methods. However, the effects of TakeCARE on bystander behavior were moderated by students’ perceptions of campus responsiveness to sexual violence, with more potent effects when students perceived their institution as responsive to reports of sexual violence

    Floração de espécies apícolas no Pantanal baseada em informações de herbário e literatura.

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    O objetivo desse estudo foi descrever e avaliar a influência do porte das plantas apícolas do Pantanal na ocorrência de floração ao longo do ano. As informações das espécies apícolas foram organizadas a partir da compilação de dados de literatura e do acervo do herbário CPAP, anotando-se o período de floração, porte de crescimento (herbáceo, arbustivo, arbóreo ou trepadeira), sendo que as palmeiras foram consideradas como de porte arbóreo, e a ocorrência ou não em área inundável (espécies aquáticas ou anfíbias e terrestres).bitstream/CPAP-2010/57290/1/BP91.pd

    Occurrence of Fipronil in residential house dust in the presence and absence of pets: a hint for a comprehensive toxicological assessment

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    The presence of the insecticide Fipronil and its main products of toxicological relevance, namely Sulfone and Desulfinyl, was assessed in 161 residential house dust samples in the absence (N = 101) and presence (N = 60) of cats and dogs in Italy. High-resolution mass spectrometry analysis revealed a significant difference (p &lt; 0.001) in the dust contamination in the presence of pets (median: 467 vs. 24 ng/g dry weight), even if the highest value was found in the absence of pets (82,069 vs. 67,799 ng/g dry weight). Fipronil intake estimates from dust in toddlers, computed according to US-EPA and EU-ECHA guidelines, ranged from 333 to 556 and from 20 to 34 ng/kg per day for acute and chronic scenario, respectively. Dust seemed not able itself to lead to Fipronil overexposure with respect to acute and chronic toxicity health-based guidance values. Kittens were potentially overexposed to Fipronil under both acute (26,076 ng/kg per day) and chronic (1,633 ng/kg per day) scenarios. The mild symptomatology associated with acute intoxication could possibly determine case underreporting within pharmacosurveillance schemes. Its administration was estimated in 7.3\u20139.7 tons per year. Such a range suggests its prudent use under strict veterinary control to prevent pest resistance and ecotoxicological outcomes
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