Observation of lobes near the X-point in resonant magnetic perturbation experiments on MAST

The application of non-axisymmetric resonant magnetic perturbations (RMPs) with a toroidal mode number n=6 in the MAST tokamak produces a significant reduction in plasma energy loss associated with type-I Edge Localized Modes (ELMs), the first such observation with n>3. During the ELM mitigated stage clear lobe structures are observed in visible-light imaging of the X-point region. These lobes or manifold structures, that were predicted previously, have been observed for the first time in a range of discharges and their appearance is correlated with the effect of RMPs on the plasma i.e. they only appear above a threshold when a density pump out is observed or when the ELM frequency is increased. They appear to be correlated with the RMPs penetrating the plasma and may be important in explaining why the ELM frequency increases. The number and location of the structures observed can be well described using vacuum modelling. Differences in radial extent and poloidal width from vacuum modelling are likely to be due to a combination of transport effects and plasma screening.Comment: 15 pages, 5 figure

Single fibre action potentials in skeletal muscle related to recording distances

Single muscle fibre action potentials (SFAPs) are considered to be functions of a bioelectrical source and electrical conductivity parameters of the medium. In most model studies SFAPs are computed as a convolution of the bioelectrical source with a transfer function. Calculated peak-to-peak amplitudes of SFAPs decrease with increasing recording distances. In this paper an experimental validation of model results is presented. Experiments were carried out on the m. extensor digitorum longus (EDL) of the rat. Using a method including fluorescent labelling of the active fibre, the distance between the active fibre and the recording electrode was derived. With another method, the decline of the peak-to-peak amplitude of SFAPs detected along a multi-electrode was obtained. With both experimental methods, in general peak-to-peak amplitudes of SFAPs decreased with increasing recording distances, as was found in model results with present volume conduction theory. However, this behaviour was not found in all experiments. The rate of decline of the peak-to-peak amplitudes with recording distance was always less than in models

Local dependence of ion temperature gradient on magnetic configuration, rotational shear and turbulent heat flux in MAST

Experimental data from the Mega Amp Spherical Tokamak (MAST) is used to show that the inverse gradient scale length of the ion temperature R/LTi (normalized to the major radius R) has its strongest local correlation with the rotational shear and the pitch angle of the magnetic field (or, equivalently, an inverse correlation with q/{\epsilon}, the safety factor/the inverse aspect ratio). Furthermore, R/LTi is found to be inversely correlated with the gyro-Bohm-normalized local turbulent heat flux estimated from the density fluctuation level measured using a 2D Beam Emission Spectroscopy (BES) diagnostic. These results can be explained in terms of the conjecture that the turbulent system adjusts to keep R/LTi close to a certain critical value (marginal for the excitation of turbulence) determined by local equilibrium parameters (although not necessarily by linear stability).Comment: 6 pages, 3 figures, submitted to PR

Hampton Roads Sea Level Rise Preparedness and Resilience Intergovernmental Pilot Project. Phase 2 Report: Recommendations, Accomplishments and Lessons Learned

Executive Summary After two years, the Hampton Roads Sea level Rise and Resilience Intergovernmental Planning Pilot Project (Intergovernmental Pilot Project or IPP), convened at Old Dominion University, has come to a successful close. Although the conclusion of the project is different than originally imagined by the drafters of the IPP Charter, the process in and of itself brought hundreds of stakeholders together, built lasting and ongoing relationships, and produced many workable recommendations for the region that can be accomplished by a variety of partnerships. The key deliverables include a whole of government mitigation and adaptation planning process and an integrated regional recommendation, both which can serve as a template for other regions. Additionally the IPP demonstrated a new role for an urban campus to act as a community convener, matching focused research and curriculum development with public service across the university and the region. Initiated in June 2014, the IPP was an effort to use the knowledge, skills and expertise of all regional stakeholders to create a framework or template for intergovernmental strategic planning that could be used outside the region; and, to implement that integrated strategy in Hampton Roads, Virginia, creating an effective and efficient method for planning holistically for sea level rise and recurrent flooding. This “Whole of Government and Community” effort would not have been successful without the hundreds of stakeholders and volunteer leaders from across all levels of government, academia, and the community who participated out of a sense of duty to their community and commitment to the collaboration. Knowing water knows no jurisdictional bounds, a high level of intergovernmental collaboration is necessary to develop integrated regional solutions and implement effective sea level rise preparedness and resilience strategies. Additionally, the wider community in Hampton Roads recognizes that they too will be affected by not only sea level rise itself, but also the adaptation strategies implemented in preparation. Executive Summary Phase 2 Report: Recommendations, Accomplishments and Lessons Learned Executive Summary 11 Phase 1 of the project, from June 2014 through June 2015, saw the drafting and signing of a Charter, the recruitment of a steering committee, a host of events, and the development of working group and advisory committees comprised of subject matter experts. Phase 2, from June 2015 through June 2016, included heavy discussion with regard to ongoing strategies for intergovernmental collaboration as well as research, a number of case studies carried out by committees and working groups, and the careful development of recommendations for the region. The IPP concludes successfully with a series of recommendations from each working group and committee as well as a final resolution drafted by the Legal Working Group and containing the consensus views of steering committee members. Though the recommendations vary in specificity and subject area, a few themes are clear. In order to move forward regionally, local stakeholders need to maintain, institutionalize and build relationships with each other in order to facilitate effective collaboration and information sharing. Institutionalizing these relationships and partnerships is key, as people shift positions throughout their careers. Additionally, while more data is needed, the methods by which that data is integrated and shared are equally important. Further, some form of the Whole of Government and Community approach that focuses on the watershed as opposed to jurisdictional boundaries is essential to accomplishing the recommendations set forth in this report. The IPP has been a success because of the dedicated volunteers committed to a resilient Hampton Roads. During the last two years, this project advanced regional adaptation through the evaluation and recommendation of a future governance structure, the development of working group and committee recommendations, building public awareness, building awareness of the need for federal agency involvement locally and building relationships among numerous organizations involved in the Pilot Project. All of this work, which in pieces may be specific only to a unique circumstance or area, when taken as a whole, brings foundational change. It builds on previous work accomplished by other leaders in the Hampton Roads region and should be leveraged in the future to accelerate regional adaptation

Flavor SU(3) breaking effects in the chiral unitary model for meson-baryon scatterings

We examine flavor SU(3) breaking effects on meson-baryon scattering amplitudes in the chiral unitary model. It turns out that the SU(3) breaking, which appears in the leading quark mass term in the chiral expansion, can not explain the channel dependence of the subtraction parameters of the model, which are crucial to reproduce the observed scattering amplitudes and resonance properties.Comment: RevTeX4, 4 pages, 3 figures, 2 table

Chiral dynamics of p-wave in K^- p and coupled states

We perform an evaluation of the p-wave amplitudes of meson-baryon scattering in the strangeness S=-1 sector starting from the lowest order chiral Lagrangians and introducing explicitly the Sigma^* field with couplings to the meson-baryon states obtained using SU(6) symmetry. The N/D method of unitarization is used, equivalent, in practice, to the use of the Bethe-Salpeter equation with a cut-off. The procedure leaves no freedom for the p-waves once the s-waves are fixed and thus one obtains genuine predictions for the p-wave scattering amplitudes, which are in good agreement with experimental results for differential cross sections, as well as for the width and partial decay widths of the Sigma^*(1385).Comment: LaTeX, 18 pages, 6 figure