188 research outputs found
A model for microinstability destabilization and enhanced transport in the presence of shielded 3-D magnetic perturbations
A mechanism is presented that suggests shielded 3-D magnetic perturbations
can destabilize microinstabilities and enhance the associated anomalous
transport. Using local 3-D equilibrium theory, shaped tokamak equilibria with
small 3-D deformations are constructed. In the vicinity of rational magnetic
surfaces, the infinite-n ideal MHD ballooning stability boundary is strongly
perturbed by the 3-D modulations of the local magnetic shear associated with
the presence of nearresonant Pfirsch-Schluter currents. These currents are
driven by 3-D components of the magnetic field spectrum even when there is no
resonant radial component. The infinite-n ideal ballooning stability boundary
is often used as a proxy for the onset of virulent kinetic ballooning modes
(KBM) and associated stiff transport. These results suggest that the achievable
pressure gradient may be lowered in the vicinity of low order rational surfaces
when 3-D magnetic perturbations are applied. This mechanism may provide an
explanation for the observed reduction in the peak pressure gradient at the top
of the edge pedestal during experiments where edge localized modes have been
completely suppressed by applied 3-D magnetic fields
Determining the economic costs and benefits of conservation actions: A decision support framework
The need for conservation action to be cost-effective is widely accepted, resulting in increased interest and effort to assess effectiveness. Assessing the financial and economic costs of conservation is equally important for assessing cost-effectiveness, yet their measurement and assessment are repeatedly identified as lacking. The healthcare sector, in contrast, has made substantial progress in identifying and including costs in decision-making. Here, we consider what conservation can learn from this experience. We present a three-step framework for identifying and recording the relevant economic costs and benefits of conservation interventions where the user (1) describes the costing context, (2) determines which types of cost and benefit to include, and (3) obtains values for these costs and benefits alongside metadata necessary for others to interpret the data. This framework is designed to help estimate economic costs but can also be used flexibly to record the direct costs of interventions (i.e., financial costs) and calculate financial and economic benefits. Although recording data on economic costs and benefits is deceptively complex, this framework facilitates improved recording, and indicates how collating this data could enhance the assessment of cost-effectiveness across conservation contexts using a range of decision-making tools. © 2022 The Authors. Conservation Science and Practice published by Wiley Periodicals LLC on behalf of Society for ConservationWe thank Alec Christie, Ashley Simkins, and Anthony Waldron for helpful discussions and Arcadia, MAVA, and the David and Claudia Harding Foundation for funding. We thank two anonymous reviewers, and Gwen Iacona for detailed comments that helped improve the manuscript. The work was completed by Thomas White as part of a PhD supported by a Balfour studentship at the Department of Zoology, University of Cambridge
Giants On Deformed Backgrounds
We study giant graviton probes in the framework of the three--parameter
deformation of the AdS_5 x S^5 background. We examine both the case when the
brane expands in the deformed part of the geometry and the case when it blows
up into AdS. Performing a detailed analysis of small fluctuations around the
giants, the configurations turn out to be stable. Our results hold even for the
supersymmetric Lunin-Maldacena deformation.Comment: LaTex, 28 pages, uses JHEP3; v2: minor corrections, references added;
v3: final version accepted for publication in JHE
UV/IR Mixing and Anomalies in Noncommutative Gauge Theories
Using path integral method (Fujikawa's method) we calculate anomalies in
noncommutative gauge theories with fermions in the bi-fundamental and adjoint
representations. We find that axial and chiral gauge anomalies coming from
non-planar contributions are derived in the low noncommutative momentum limit
. The adjoint chiral
fermion carries no anomaly in the non-planar sector in
dimensions. It is naturally shown from the path integral method that anomalies
in non-planar sector originate in UV/IR mixing.Comment: 15 pages, no figures, LaTeX, minor corrections and references adde
Making things happen : a model of proactive motivation
Being proactive is about making things happen, anticipating and preventing problems, and seizing opportunities. It involves self-initiated efforts to bring about change in the work environment and/or oneself to achieve a different future. The authors develop existing perspectives on this topic by identifying proactivity as a goal-driven process involving both the setting of a proactive goal (proactive goal generation) and striving to achieve that proactive goal (proactive goal striving). The authors identify a range of proactive goals that individuals can pursue in organizations. These vary on two dimensions: the future they aim to bring about (achieving a better personal fit within oneâs work environment, improving the organizationâs internal functioning, or enhancing the organizationâs strategic fit with its environment) and whether the self or situation is being changed. The authors then identify âcan do,â âreason to,â and âenergized toâ motivational states that prompt proactive goal generation and sustain goal striving. Can do motivation arises from perceptions of self-efficacy, control, and (low) cost. Reason to motivation relates to why someone is proactive, including reasons flowing from intrinsic, integrated, and identified motivation. Energized to motivation refers to activated positive affective states that prompt proactive goal processes. The authors suggest more distal antecedents, including individual differences (e.g., personality, values, knowledge and ability) as well as contextual variations in leadership, work design, and interpersonal climate, that influence the proactive motivational states and thereby boost or inhibit proactive goal processes. Finally, the authors summarize priorities for future researc
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