Quark mixing from softly broken symmetries

Quark flavor mixing may originate in the soft breaking of horizontal symmetries. Those symmetries, which in the simplest case are three family U(1) groups, are obeyed only by the dimension-4 Yukawa couplings and lead, when unbroken, to the absence of mixing. Their breaking may arise from the dimension-3 mass terms of SU(2)-singlet vector-like quarks. Those gauge-singlet mass terms break the horizontal symmetries at a scale much higher than the Fermi scale, yet softly, leading to quark mixing while the quark masses remain unsuppressed.Comment: 9 pages, plain Latex, no figure

Improving the eco-efficiency of an agricultural water use system

During the last two decades, the concept of eco-efficiency has been recognized as a suitable measure of progress towards a greener and more sustainable economy. The prefix “eco-” refers to both economic and ecological (environmental) performance. The need for improving eco-efficiency leads to the challenge of identifying the most promising alternative solutions which improve both the economic and the environmental performance of a given system (“eco-innovations”). Therefore, it becomes critical to develop eco-efficiency metrics for measuring environmental and economic performance of a system. The current paper presents a methodological framework that attempts to explore the use of eco-efficiency indicators in meso-level water use systems and through them to assess the impact of innovative technologies in such systems. The assessment of the environmental performance follows a life-cycle oriented approach using the midpoint impact categories while the economic performance is measured using the Total Value Added to the product due to water use. The eco-efficiency is expressed as the ratio of the economic performance indicator to the environmental performance indicator. The proposed approach is applied to a water use system of the agricultural sector, and more specifically to the fresh form tomato crop production in Phthiotida. The analysis reveals that the most important environmental impacts of the system are (i) greenhouse gas emissions due to energy consumption, (ii) release of toxic substances, due to the use of fertilizers and pesticides and (iii) depletion of freshwater resources. Three alternative interventions are examined for upgrading the value chain: (i) installation of sub-surface drip irrigation system, (ii) replacement of diesel pumps with solar pumps and (iii) use of organic fertilizers. Based on the findings, all of the proposed interventions have a positive impact on the overall eco-efficiency of the system. Sub-surface drip irrigation is the least favorable mainly due to its high investment cost. The use of solar pumps strongly influences climate change and photochemical ozone formation while the use of organic fertilizers has a more balanced impact on all indicators, with an emphasis on eutrophication. Thus, for a more holistic approach, regarding the eco-efficiency performance, a combined application of these three scenarios may be proposed

Estimating potential incidence of MERS-CoV associated with Hajj pilgrims to Saudi Arabia, 2014

Between March and June 2014 the Kingdom of Saudi Arabia (KSA) had a large outbreak of MERS-CoV, renewing fears of a major outbreak during the Hajj this October. Using KSA Ministry of Health data, the MERS-CoV Scenario and Modeling Working Group forecast incidence under three scenarios. In the expected incidence scenario, we estimate 6.2 (95% Prediction Interval [PI]: 1-17) pilgrims will develop MERS-CoV symptoms during the Hajj, and 4.0 (95% PI: 0-12) foreign pilgrims will be infected but return home before developing symptoms. In the most pessimistic scenario, 47.6 (95% PI: 32-66) cases will develop symptoms during the Hajj, and 29.0 (95% PI: 17-43) will be infected but return home asymptomatic. Large numbers of MERS-CoV cases are unlikely to occur during the 2014 Hajj even under pessimistic assumptions, but careful monitoring is still needed to detect possible mass infection events and minimize introductions into other countries

The Fate of Nearly Supersymmetric Vacua

Supersymmetric vacua are stable. It is interesting to ask: how long-lived are vacua which are nearly supersymmetric? This question is relevant if our universe is approximately supersymmetric. It is also of importance for a number of issues of the physics of the landscape and eternal inflation. In this note, we distinguish a variety of cases. In all of them the decay is slow. For a flat space theory decaying to a deep AdS vacuum, the leading behavior of the decay amplitude, if a thin wall approximation is valid, is ${\cal A} = \gamma e^{-2 \pi^2/({\rm Re} m_{3/2})^2}$ (where the phase of $m_{3/2}$ is defined in the text) for ${\rm Re} m_{3/2}>0$, and zero otherwise. Metastable supersymmetry breaking generally yields parametrically more rapid decays. For nearly supersymmetric decays, we will see that it is necessary to compute subleading terms in the exponential to extraordinarily high accuracy before one can meaningfully discuss the prefactor.Comment: 19 page

Modelling of JET hybrid scenarios with GLF23 transport model: E × B shear stabilization of anomalous transport

The E&nbsp;×&nbsp;B shear stabilization of anomalous transport in JET hybrid discharges is studied via self-consistent predictive modelling of electron and ion temperature, ion density and toroidal rotation velocity performed with the GLF23 model. The E&nbsp;×&nbsp;B shear stabilization factor (parameter α E in the GLF23 model) is adjusted to predict accurately the four simulated quantities under different experimental conditions, and the uncertainty in α E determined by 15% deviation between simulated and measured quantities is estimated. A correlation of α E with toroidal rotation velocity and E&nbsp;×&nbsp;B shearing rate is found in the low density plasmas, suggesting that the turbulence quench rule may be more complicated than assumed in the GLF23 model with constant α E . For the selected discharges the best predictive accuracy is obtained by using weak/no E&nbsp;×&nbsp;B shear stabilization (i.e. α E&nbsp;≈&nbsp;0) at low toroidal angular frequency (Ω&nbsp;&lt;&nbsp;60&nbsp;krad&nbsp;s −1 ), even in the scenarios with the current overshoot, and α E&nbsp;=&nbsp;0.9 at high frequency (Ω&nbsp;&gt;&nbsp;100&nbsp;krad&nbsp;s −1 ). Interestingly, a weak E&nbsp;×&nbsp; B shear stabilization of anomalous transport is found in the medium density strongly rotating discharge. An importance of linear β e stabilization in this discharge is estimated and compared to the low density discharge with equally high β e . The toroidal rotation velocity is well predicted here by assuming that the momentum diffusion coefficient is a fraction of thermal ion diffusivity. Taking into account the α E and Prandtl number with their uncertainties determined in the modelling of JET hybrid discharges, the performance of ITER hybrid scenario with optimized heat mix (33&nbsp;MW of NBI and 20&nbsp;MW of ECCD) is estimated showing the importance of toroidal rotation for achieving Q &nbsp;&gt;&nbsp;5.</p

Modelling of hybrid scenario: from present-day experiments towards ITER

The ‘hybrid’ scenario is an attractive operating scenario for ITER since it combines long plasma duration with the reliability of the reference H-mode regime. We review the recent European modelling effort carried out within the Integrated Scenario Modelling group which aims at (i) understanding the underlying physics of the hybrid regime in ASDEX-Upgrade and JET and (ii) extrapolating them towards ITER. JET and ASDEX-Upgrade hybrid scenarios performed under different experimental conditions have been simulated in an interpretative and predictive way in order to address the current profile dynamics and its link with core confinement, the relative importance of magnetic shear, s , and E&nbsp;×&nbsp;B flow shear on the core turbulence, pedestal stability and H–L transition. The correlation of the improved confinement with an increased s / q at outer radii observed in JET and ASDEX-Upgrade discharges is consistent with the predictions based on the GLF23 model applied in the simulations of the ion and electron kinetic profiles. Projections to ITER hybrid scenarios have been carried out focusing on optimization of the heating/current drive schemes to reach and ultimately control the desired plasma equilibrium using ITER actuators. Firstly, access condition to the hybrid-like q -profiles during the current ramp–up phase has been investigated. Secondly, from the interpreted role of the s / q ratio, ITER hybrid scenario flat-top performance has been optimized through tailoring the q -profile shape and pedestal conditions. EPED predictions of pedestal pressure and width have been used as constraints in the interpretative modelling while the core heat transport is predicted by GLF23. Finally, model-based approach for real-time control of advanced tokamak scenarios has been applied to ITER hybrid regime for simultaneous magnetic and kinetic profile control.</p