3,231 research outputs found

    Controlling Excitations Inversion of a Cooper Pair Box Interacting with a Nanomechanical Resonator

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    We investigate the action of time dependent detunings upon the excitation inversion of a Cooper pair box interacting with a nanomechanical resonator. The method employs the Jaynes-Cummings model with damping, assuming different decay rates of the Cooper pair box and various fixed and t-dependent detunings. It is shown that while the presence of damping plus constant detunings destroy the collapse/revival effects, convenient choices of time dependent detunings allow one to reconstruct such events in a perfect way. It is also shown that the mean excitation of the nanomechanical resonator is more robust against damping of the Cooper pair box for convenient values of t-dependent detunings.Comment: 11 pages, 5 figure

    Weak Pion Production off the Nucleon

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    We develop a model for the weak pion production off the nucleon, which besides the Delta pole mechanism (weak excitation of the Δ(1232)\Delta(1232) resonance and its subsequent decay into NπN\pi), includes also some background terms required by chiral symmetry. We re-fit the C5A(q2)C_5^A(q^2) form factor to the flux averaged νμpμpπ+\nu_\mu p \to \mu^-p\pi^+ ANL q2q^2-differential cross section data, finding a substantially smaller contribution of the Delta pole mechanism than traditionally assumed in the literature. Within this scheme, we calculate several differential and integrated cross sections, including pion angular distributions, induced by neutrinos and antineutrinos and driven both by charged and neutral currents. In all cases we find that the background terms produce quite significant effects and that they lead to an overall improved description of the data, as compared to the case where only the Delta pole mechanism is considered. We also show that the interference between the Delta pole and the background terms produces parity-violating contributions to the pion angular differential cross section, which are intimately linked to TT-odd correlations in the contraction between the leptonic and hadronic tensors. However, these latter correlations do not imply a genuine violation of time reversal invariance because of the existence of strong final state interaction effects.Comment: Typos corrected; comments adde

    N-Delta(1232) axial form factors from weak pion production

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    The N-Delta axial form factors are determined from neutrino induced pion production ANL & BNL data by using a state of the art theoretical model, which accounts both for background mechanisms and deuteron effects. We find violations of the off diagonal Goldberger-Treiman relation at the level of 2 sigma which might have an impact in background calculations for T2K and MiniBooNE low energy neutrino oscillation precision experiments.Comment: 4 pages, 1 figur

    Contribution of distribution network control to voltage stability: A case study

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    A case study dealing with long-term voltage instability in systems hosting active distribution networks (DN) is reported in this paper. It anticipates future situations with high penetration of dispersed generation (DG), where the latter are used to keep distribution voltages within desired limits, in complement to load tap changers. The interactions between transmission and active DN are investigated on a 3108-bus test system. It involves transmission grid, large generators, and 40 DN, each with DG steered by a controller inspired by model predictive control. The reported simulations show the impact of distribution network voltage restoration, as well as the benefit of load voltage reduction actuated by the dispersed generators

    Anodic reactions and the corrosion of copper in deep eutectic solvents

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    An analysis of the anodic reaction occurring at soluble copper anodes during the electrodeposition of copper from an ethaline-based deep eutectic solvent (DES) has been performed. It was shown by UV-Vis spectroscopy and electrochemical measurements that the dominant anodic species produced is the CuCl2- complex. In pure ethaline the current efficiency of the anodic process is 100% and the dissolution valency is one. However, in the presence of Cu(II) species the apparent dissolution valency measured gravimetrically was typically less than unity, corresponding to an observed mass loss greater than that expected from Faraday’s law. Moreover, the apparent dissolution valency showed a marked dependence on the electrode rotation rate, Cu(II) concentration and the water content of the deep eutectic solvent. These observations were consistent with a corrosion reaction occurring in parallel with anodic dissolution. The most likely corrosion process is the comproportionation reaction: 2CuCl2- CuCl42- + Cu. Voltammetric data indicate that the rate of this process is controlled by the mass transport of the CuCl42- complex to the surface and can readily explain the observed dissolution valency dependencies. Finally, it is noted that anomalous dissolution of Cu anodes in deep eutectic solvents makes their implementation as soluble anodes problematic

    Effect of a spacer moiety on radiometal labelled Neurotensin derivatives

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    The binding sequence of the regulatory peptide Neurotensin, NT(8-13), represents apromising tumour-specific vector for the development of radiopeptides useful in nuclear oncology for the diagnosis (imaging) and therapy of cancer. Anumber of radiometal-labelled NT(8-13) derivatives have been reported, however, the effect of the spacer which connects the vector with the radiometal complex has yet not been investigated systematically. Because aspacer moiety can influence potentially important biological characteristics of radiopeptides, we synthesized three [DOTA(177Lu)]-X-NT(8-13) derivatives and evaluated the effect of aspacer (X) on the physico-chemical properties of the conjugate including lipophilicity, stability, and in vitro receptor affinity and cell internalizatio

    Tversky loss function for image segmentation using 3D fully convolutional deep networks

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    Fully convolutional deep neural networks carry out excellent potential for fast and accurate image segmentation. One of the main challenges in training these networks is data imbalance, which is particularly problematic in medical imaging applications such as lesion segmentation where the number of lesion voxels is often much lower than the number of non-lesion voxels. Training with unbalanced data can lead to predictions that are severely biased towards high precision but low recall (sensitivity), which is undesired especially in medical applications where false negatives are much less tolerable than false positives. Several methods have been proposed to deal with this problem including balanced sampling, two step training, sample re-weighting, and similarity loss functions. In this paper, we propose a generalized loss function based on the Tversky index to address the issue of data imbalance and achieve much better trade-off between precision and recall in training 3D fully convolutional deep neural networks. Experimental results in multiple sclerosis lesion segmentation on magnetic resonance images show improved F2 score, Dice coefficient, and the area under the precision-recall curve in test data. Based on these results we suggest Tversky loss function as a generalized framework to effectively train deep neural networks

    Neutrino induced threshold production of two pions and N^*(1440) electroweak form factors

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    We study the threshold production of two pions induced by neutrinos in nucleon targets. The contribution of nucleon, pion and contact terms are calculated using a chiral Lagrangian. The contribution of the Roper resonance, neglected in earlier studies, has also been taken into account. The numerical results for the cross sections are presented and compared with the available experimental data. It has been found that in the two pion channels with π+π\pi^+\pi^- and π0π0\pi^0\pi^0 in the final state, the contribution of the N(1440)N^*(1440) is quite important and could be used to determine the N(1440)N^*(1440) electroweak transition form factors if experimental data with better statistics become available in the future.Comment: This version corrects a mistake on the helicity amplitudes sign. Additional comments on resonance-background relative sign are added. Other minor corrections. Matches published version. 17 pages, 7 figure

    Neutrino Interactions Importance for Nuclear Physics

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    We review the general interplay between Nuclear Physics and neutrino-nucleus cross sections at intermediate and high energies. The effects of different reaction mechanisms over the neutrino observables are illustrated with examples in calculations using several nuclear models and ingredients.Comment: To appear in the proceedings of 6th International Workshop on Neutrino-Nucleus Interactions in the Few-GeV Region (NuInt09), Sitges, Spain, 18 - 22 May 200
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