1,229 research outputs found
Realistic Estimates of the Uncertainties and the Reliability Indices for Shallow Foundation Design Considering Seismic Loading
Risk and Reliability in Geotechnical Engineerin
Two-Frequency Jahn-Teller Systems in Circuit QED
We investigate the simulation of Jahn-Teller models with two non-degenerate
vibrational modes using a circuit QED architecture. Typical Jahn-Teller systems
are anisotropic and require at least a two-frequency description. The proposed
simulator consists of two superconducting lumped-element resonators interacting
with a common flux qubit in the ultrastrong coupling regime. We translate the
circuit QED model of the system to a two-frequency Jahn-Teller Hamiltonian and
calculate its energy eigenvalues and the emission spectrum of the cavities. It
is shown that the system can be systematically tuned to an effective single
mode Hamiltonian from the two-mode model by varying the coupling strength
between the resonators. The flexibility in manipulating the parameters of the
circuit QED simulator permits isolating the effective single frequency and pure
two-frequency effects in the spectral response of Jahn-Teller systems.Comment: 8 pages, 4 figures, figures revise
Unitarity analysis of general Born-Infeld gravity theories
We develop techniques of analyzing the unitarity of general Born-Infeld (BI)
gravity actions in D-dimensional spacetimes. Determinantal form of the action
allows us to find a compact expression quadratic in the metric fluctuations
around constant curvature backgrounds. This is highly nontrivial since for the
BI actions, in principle, infinitely many terms in the curvature expansion
should contribute to the quadratic action in the metric fluctuations around
constant curvature backgrounds, which would render the unitarity analysis
intractable. Moreover in even dimensions, unitarity of the theory depends only
on finite number of terms built from the powers of the curvature tensor. We
apply our techniques to some four-dimensional examples.Comment: 26 pages, typos corrected, version to appear in Phys. Rev.
Public behaviour in response to the Covid-19 pandemic: Understanding the role of group processes
Background
In the absence of a vaccine, behaviour by the public is key to the response to the Covid-19 pandemic. Yet, as with other types of crises and emergencies, there have been doubts about the extent to which the public are able to engage effectively with the required behaviour. These doubts are based on outdated models of group psychology.
Aims and argument
We analyse the role of group processes in the Covid-19 pandemic in three domains: recognition of threat; adherence by the public to the required public health behaviours (and the factors that increase such adherence); and actions of the many community mutual aid groups that arose during lockdown. In each case, we draw upon the accumulated research on behaviour in emergencies and disasters as well as the latest findings in relation to the Covid-19 pandemic to show that explanations in terms of social identity processes make better sense of the patterns of evidence than alternative explanations.
Conclusion
If behaviour in the pandemic is a function of mutable group processes rather than fixed tendencies, then behavioural change is possible. There was evidence of significant change in behaviour from the public, particularly in the early days of the pandemic. Understanding the role of group processes means we can help design more effective interventions to support collective resilience in the public in the face of the pandemic and other threats. We draw out from the evidence a set of recommendations on facilitating the public response to Covid-19 by harnessing group processes
Shortcuts to high symmetry solutions in gravitational theories
We apply the Weyl method, as sanctioned by Palais' symmetric criticality
theorems, to obtain those -highly symmetric -geometries amenable to explicit
solution, in generic gravitational models and dimension. The technique consists
of judiciously violating the rules of variational principles by inserting
highly symmetric, and seemingly gauge fixed, metrics into the action, then
varying it directly to arrive at a small number of transparent, indexless,
field equations. Illustrations include spherically and axially symmetric
solutions in a wide range of models beyond D=4 Einstein theory; already at D=4,
novel results emerge such as exclusion of Schwarzschild solutions in cubic
curvature models and restrictions on ``independent'' integration parameters in
quadratic ones. Another application of Weyl's method is an easy derivation of
Birkhoff's theorem in systems with only tensor modes. Other uses are also
suggested.Comment: 10 page
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Fear of COVID-19, mindfulness, humor, and hopelessness: a multiple mediation analysis
Hopelessness is an important vulnerability factor for depressive symptomology and suicidal ideations. It may also play an important role in the fear of coronavirus 2019 (COVID-19). Therefore, the present study tested the mediating role of mindful awareness and humor (both identified as coping strategies for dealing with stressful situations) in the relationship between fear of COVID-19 and hopelessness. Participants comprised 786 Turkish individuals (562 females and 224 males; aged between 18 and 67 years) from 71 of 81 cities in Turkey. An online convenience sampling method was used to recruit participants. Participants completed surveys including the Fear of COVID-19 Scale, Beck Hopelessness Scale, Mindful Attention Awareness Scale, and Coping Humor Scale. The model was tested using structural equation modeling (SEM) and utilizing bootstrapping. The results of SEM showed that the effect of fear of COVID-19 on hopelessness was partly mediated by mindfulness and humor, and which was supported by bootstrapping. Therefore, higher fear of COVID-19 was associated with lower mindfulness and humor. In turn, lower mindfulness and humor were related with higher hopelessness. Findings are discussed in the context of COVID-19 and the hopelessness literature, and practical implications for counselors are also provided
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