1,576 research outputs found

    Supersymmetric methods in the traveling variable: inside neurons and at the brain scale

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    We apply the mathematical technique of factorization of differential operators to two different problems. First we review our results related to the supersymmetry of the Montroll kinks moving onto the microtubule walls as well as mentioning the sine-Gordon model for the microtubule nonlinear excitations. Second, we find analytic expressions for a class of one-parameter solutions of a sort of diffusion equation of Bessel type that is obtained by supersymmetry from the homogeneous form of a simple damped wave equations derived in the works of P.A. Robinson and collaborators for the corticothalamic system. We also present a possible interpretation of the diffusion equation in the brain contextComment: 14 pages, 1 figur

    Influence of a transverse static magnetic field on the magnetic hyperthermia properties and high-frequency hysteresis loops of ferromagnetic FeCo nanoparticles

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    The influence of a transverse static magnetic field on the magnetic hyperthermia properties is studied on a system of large-losses ferromagnetic FeCo nanoparticles. The simultaneous measurement of the high-frequency hysteresis loops and of the temperature rise provides an interesting insight into the losses and heating mechanisms. A static magnetic field of only 40 mT is enough to cancel the heating properties of the nanoparticles, a result reproduced using numerical simulations of hysteresis loops. These results cast doubt on the possibility to perform someday magnetic hyperthermia inside a magnetic resonance imaging setup.Comment: 6 pages, 3 figure

    Supersymmetric free-damped oscillators: Adaptive observer estimation of the Riccati parameter

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    A supersymmetric class of free damped oscillators with three parameters has been obtained in 1998 by Rosu and Reyes through the factorization of the Newton equation. The supplementary parameter is the integration constant of the general Riccati solution. The estimation of the latter parameter is performed here by employing the recent adaptive observer scheme of Besancon et al., but applied in a nonstandard form in which a time-varying quantity containing the unknown Riccati parameter is estimated first. Results of computer simulations are presented to illustrate the good feasibility of this approach for a case in which the estimation is not easily accomplished by other meansComment: 8 pages, 6 figure

    Quasi elastic cross sections for the Bi-209(e, e \u27 p)Pb-208 reaction: Jefferson Lab experiment E06007

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    Quasi elastic cross sections were measured for the first time for both negative and positive missing momenta for the Bi-209(e, e\u27p)Pb-208 reaction leading to the ground state and hole states of Pb-208. Experimental cross sections obtained between -0.3 GeV/c to 0.3 GeV/c agree with theoretical calculations using RDWIA techniques both in shape and magnitude for the ground state. The data for the ground state production of Pb-208 are consistent with a theoretical model assuming a single proton(1.06 +/- 0.10) in the 1h9/2 orbit in Bi-209

    Dissecting a vegetable landrace: Components of variation in Spanish ?Moruno? tomatoes as a case studio

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    The variability of landraces is dissected and related to farmers' practices through surveys. Spanish 'Moruno' tomatoes, recognised for their excellent flavour, were selected as a case study. For this purpose, 30 populations were characterised in a four-year program. Higher intra-population than inter-population variability was found. Variability is generally reduced in the traits used by farmers as selection criteria. Farmers rarely used flavour as a selection criterion, but it is one of the main characteristics used by them to define the landrace. Seed exchange and growing different landraces simultaneously are commonplace, and outcrossing might occur, thus justifying in part the seed degeneration problems experienced by some farmers. At the same time, farmers select seeds for the next year on a per-fruit basis rather than a per-plant basis, justifying the maintenance of a high level of variability. In such cases, high pressure would be applied to key morphological traits but not to flavour. Accordingly, the sugars, acids and volatiles profiles related to flavour in the landraces' populations are highly variable, though the environment also exercises a high effect. It is necessary to make population selections to offer farmers materials combining the best organoleptic perception and a high stable yield. This would reduce the gap between the price premium received by farmers and the expected fair price. It would also be necessary to develop consumer information campaigns to exploit their willingness to pay for the extra value offered by landraces. Only then long-term on-farm conservation would be economically feasible. Although achieving a trade-off between yield and flavour is difficult, it is possible to identify populations that reach a compromise between them. In germplasm banks, it is impossible to evaluate all the materials in the same year. The use of hybrid controls, with no genetic variation, is helpful in considering the environmental effects. Still, genotype x environment interactions are evident, and using selected control populations of landraces is necessary to evaluate possible performances closer to the type of materials being evaluated

    Precision Electron-Beam Polarimetry at 1 GeV Using Diamond Microstrip Detectors

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    We report on the highest precision yet achieved in the measurement of the polarization of a low-energy, O(1 GeV), continuous-wave (CW) electron beam, accomplished using a new polarimeter based on electron-photon scattering, in Hall C at Jefferson Lab. A number of technical innovations were necessary, including a novel method for precise control of the laser polarization in a cavity and a novel diamond microstrip detector that was able to capture most of the spectrum of scattered electrons. The data analysis technique exploited track finding, the high granularity of the detector, and its large acceptance. The polarization of the 180-mu A, 1.16-GeV electron beam was measured with a statistical precision of \u3c 1% per hour and a systematic uncertainty of 0.59%. This exceeds the level of precision required by the Qweak experiment, a measurement of the weak vector charge of the proton. Proposed future low-energy experiments require polarization uncertainty \u3c 0.4%, and this result represents an important demonstration of that possibility. This measurement is the first use of diamond detectors for particle tracking in an experiment. It demonstrates the stable operation of a diamond-based tracking detector in a high radiation environment, for two years

    Impact of Local Congruences in Attribute Reduction

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    Local congruences are equivalence relations whose equivalence classes are convex sublattices of the original lattice. In this paper, we present a study that relates local congruences to attribute reduction in FCA. Specifically, we will analyze the impact in the context of the use of local congruences, when they are used for complementing an attribute reduction

    Fast adiabatic transport of single laser-cooled 9^9Be+^+ ions in a cryogenic Penning trap stack

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    High precision mass and gg-factor measurements in Penning traps have enabled groundbreaking tests of fundamental physics. The most advanced setups use multi-trap methods, which employ transport of particles between specialized trap zones. Present developments focused on the implementation of sympathetic laser cooling will enable significantly shorter duty cycles and better accuracies in many of these scenarios. To take full advantage of these increased capabilities, we implement fast adiabatic transport concepts developed in the context of trapped-ion quantum information processing in a cryogenic Penning trap system. We show adiabatic transport of a single 9Be+^9\mathrm{Be}^+ ion initially cooled to 2 mK over a 2.2 cm distance within 15 ms and with less than 10\,mK energy gain at a peak velocity of 3 m/s. These results represent an important step towards the implementation of quantum logic spectroscopy in the \ppbar system. Applying these developments to other multi-trap systems has the potential to considerably increase the data-sampling rate in these experiments.Comment: 15 pages, 7 figure

    The Trichoptera of Panama VII. Additional new country records for caddisflies from the Republic of Panama

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    The Republic of Panama currently has 358 recorded species of Trichoptera. Herein we add 25 new country records for Panama. The newly recorded taxa increase Panama’s total known caddisfly fauna to 383 species, distributed among 15 families and 52 genera. These results are part of an ongoing effort to characterize the caddisfly fauna of Panama, and to evaluate that country’s major watersheds (cuencas)

    The Trichoptera of Panama VII. Additional new country records for caddisflies from the Republic of Panama

    Get PDF
    The Republic of Panama currently has 358 recorded species of Trichoptera. Herein we add 25 new country records for Panama. The newly recorded taxa increase Panama’s total known caddisfly fauna to 383 species, distributed among 15 families and 52 genera. These results are part of an ongoing effort to characterize the caddisfly fauna of Panama, and to evaluate that country’s major watersheds (cuencas)
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