3,698 research outputs found

    Reconciliation of CDM abundance and μeγ\mu\to e\gamma in a radiative seesaw model

    Full text link
    We reexamine relic abundance of a singlet fermion as a CDM candidate, which contributes to the neutrino mass generation through radiative seesaw mechanism. We search solutions for Yukawa couplings and the mass spectrum of relevant fields to explain neutrino oscillation data. For such solutions, we show that an abundance of a lightest singlet fermion can be consistent with WMAP data without conflicting with both bounds of μeγ\mu\to e\gamma and τμγ\tau\to \mu\gamma. This reconciliation does not need any modification of the original radiative seesaw model other than by specifying flavor structure of Yukawa couplings and taking account of coannihilation effects.Comment: 16 pages, 2 figures, accepted version for publication

    Neutrino masses and μ\mu terms in a supersymmetric extra U(1) model

    Full text link
    We propose a supersymmetric extra U(1) model, which can generate small neutrino masses and necessary μ\mu terms, simultaneously. Fields including quarks and leptons are embedded in three 27{\bf 27}s of E6E_6 in a different way among generations. The model has an extra U(1) gauge symmetry at TeV regions, which has discriminating features from other models studied previously. Since a neutrino mass matrix induced in the model has a constrained texture with limited parameters, it can give a prediction. If we impose neutrino oscillation data to fix those parameters, a value of sinθ13\sin\theta_{13} can be determined. We also discuss several phenomenological features which are discriminated from the ones of the MSSM.Comment: 27 pages, 2 figures, final version for publicatio

    Boosting infrared energy transfer in 3D nanoporous gold antennas

    Get PDF
    The applications of plasmonics to energy transfer from free-space radiation to molecules are currently limited to the visible region of the electromagnetic spectrum due to the intrinsic optical properties of bulk noble metals that support strong electromagnetic field confinement only close to their plasma frequency in the visible/ultraviolet range. In this work, we show that nanoporous gold can be exploited as a plasmonic material for the mid-infrared region to obtain strong electromagnetic field confinement, co-localized with target molecules into the nanopores and resonant with their vibrational frequency. The effective optical response of the nanoporous metal enables the penetration of optical fields deep into the nanopores, where molecules can be loaded thus achieving a more efficient light–matter coupling if compared to bulk gold. In order to realize plasmonic resonators made of nanoporous gold, we develop a nanofabrication method based on polymeric templates for metal deposition and we obtain antenna arrays resonating at mid-infrared wavelengths selected by design. We then coat the antennas with a thin (3 nm) silica layer acting as the target dielectric layer for optical energy transfer. We study the strength of the light–matter coupling at the vibrational absorption frequency of silica at 1240 cm−1 through the analysis of the experimental Fano lineshape that is benchmarked against identical structures made of bulk gold. The boost in the optical energy transfer from free-space mid-infrared radiation to molecular vibrations in nanoporous 3D nanoantenna arrays can open new application routes for plasmon-enhanced physical–chemical reactions

    The effect of grades on the preference effect : Grading Reduces Consideration of Disconfirming Evidence

    Get PDF
    The tendency to look for evidence that supports, rather than questions, one's viewpoint (preference effect) is a pervasive phenomenon. Although one important goal of education is developing critical thinking, the widespread practice of grading might discourage students in appreciating disconfirming evidence. We hypothesized that individual grading increases the preference effect. In Experiment 1, participants who expected to be graded exhibited a higher preference effect compared to participants who expected their work to be merely visible. Experiment 2 replicated this effect and further showed that grading increased participants' perception of a competitive social comparison. Implications for educational policies are discussed.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

    Comments Upon an Earth Dam Severely Damaged by Foundation Liquefaction

    Get PDF
    The damage of the Draganesti earth dam on lower sector of the Olt river due to foundation liquefaction during 30th May 1990, 0.12 g in site maximum acceleration, Vrancea earthquake is described. The dam is up to 20 m maximum height and border cross-wise and laterally the reservoir with 12.6 km length of the low head hydroelectric power station. The damage consisting of a large slide with about 60 m length at the dam downstream face and some cracks and lift-up of the reinforced concrete slabs at the corresponding upstream toe zone was placed in a zone where any special technology for increasing the relative density of the foundation loose sand layer was not applied. The natural relative density of the above mentioned layer having 1.20…7.00 m thickness was Dr =0.15…0.30, but it was increased up to 0.55…0.65 by vibrated-compacted gravel microcolumns technology, that was applied for over 80 % of dam foundation area. A comprehensive seismic backanalysis is performed in order to explain the damage mechanism

    Time-Dependent Framework for Analyzing Emergency Intervention Travel Times and Risk Implications due to Earthquakes. Bucharest Case Study

    Get PDF
    Earthquakes can generate a significant number of casualties within seconds, as well as high economic losses. The lack of rapid and coordinated emergency intervention can contribute to much greater losses. In this paper we develop a framework taking advantage of the ArcGis Network Analyst extension, able to account for post-earthquake conditions and reflect travel times. By combining 1) network characteristics with 2) direct seismic damage information, 3) models to determine road obstruction potential, 4) traffic information and time-dependent post-earthquake modeling but also 5) emergency intervention facilities (hospitals or fire stations) and considerations regarding their functional limitations, this framework can provide important support for the management of emergency intervention but also for risk reduction planning. Main results consist of maps showing travel times for various scenarios and moments after an earthquake, inaccessible areas, vital roads for access or an identification of important facilities. As case study we chose Bucharest, one of Europe’s most endangered capitals considering the seismic risk level. The city was and could be considerably affected by earthquakes in the Vrancea Seismic Zone, being characterized by a high number of vulnerable buildings and by one of the greatest typical traffic congestion levels in the world. Compared to previous network studies for Bucharest, the new approach is more complex and customable, providing means for real-time integration and time-dependent analysis. Results, for a worst-case scenario, prove that the risks could be even greater than expected, but also what should be done to mitigate them, such as the construction of a new hospital in the western part of the city, ensuring safe delimited routes for emergency vehicles or expanding the treatment capacity of actual hospitals—some of which also need seismic retrofitting. Results of this study will be integrated in the revised version of the National Conception for Post-Earthquake Response—an operational framework which will lead to risk mitigation through the improvement of post-disaster reaction

    A novel metric for coronal MHD models

    Get PDF
    [1] In the interest of quantitatively assessing the capabilities of coronal MHD models, we have developed a metric that compares the structures of the white light corona observed with SOHO LASCO C2 to model predictions. The MAS model is compared to C2 observations from two Carrington rotations during solar cycle 23, CR1913 and CR1984, which were near the minimum and maximum of solar activity, respectively, for three radial heights, 2.5 R⊙, 3.0 R⊙, and 4.5 R⊙. In addition to simulated polarization brightness images, we create a synthetic image based on the field topology along the line of sight in the model. This open-closed brightness is also compared to LASCO C2 after renormalization. In general, the model\u27s magnetic structure is a closer match to observed coronal structures than the model\u27s density structure. This is expected from the simplified energy equations used in current global corona MHD models
    corecore