26,778 research outputs found
Positive psychology and romantic scientism: Reply to comments on Brown, Sokal, & Friedman (2013)
This is a response to five comments [American Psychologist 69, 626-629 and
632-635 (2014)] on our article arXiv:1307.7006.Comment: PDF, 9 page
The persistence of wishful thinking: Response to "Updated thinking on positivity ratios"
This is a response to Barbara Fredrickson's comment [American Psychologist
68, 814-822 (2013)] on our article arXiv:1307.7006.
We analyze critically the renewed claims made by Fredrickson (2013)
concerning positivity ratios and "flourishing", and attempt to disentangle some
conceptual confusions; we also address the alleged empirical evidence for
nonlinear effects. We conclude that there is no evidence whatsoever for the
existence of any "tipping points", and only weak evidence for the existence of
any nonlinearity of any kind. Our original concern, that the application of
advanced mathematical techniques in psychology and related disciplines may not
always be appropriate, remains undiminished.Comment: LaTeX2e, 10 pages including 6 Postscript figure
Potential for the Conservation Security Program to Induce More Ecologically Diverse Crop Rotations in the Western Corn Belt
The potential of the USDA’s new Conservation Security Program (CSP) for inducing farmers to adopt more ecologically diverse crop rotations in the Western Corn Belt is examined. Simulations are conducted for a representative farm model in southeastern South Dakota, using different assumptions about commodity policies and CSP payments.CRP, Conservation, crop rotation, crop diversity
Forcing boundary-layer transition on an inverted airfoil in ground effect and at varying incidence
Presented at 34th AIAA Applied Aerodynamics ConferenceThe influence of the laminar boundary-layer state on a wing operating in ground effect at Re = 6 × 10 has been investigated using experiments with a model that provides two-dimensional flow and computations with a panel-method code. The effect of a boundary-layer trip placed at varying distances from the leading edge was observed at various incidences in terms of on-surface characteristics, including pressure measurements, flow visualisation and hot-film anemometry, and off-surface characteristics with LDA surveys below and behind the wing. The act of forcing transition led to downforce being reduced and drag increased, moreover, it altered almost all aspects of the wing’s aerodynamic characteristics, with the effect becoming greater as the trip was placed closer to the leading edge. These aspects include the replacement of a laminar separation bubble with trailing-edge separation, a thicker boundary layer, and a thicker wake with greater velocity deficit. The importance of considering laminar phenomena for wings operating in ground effect has been show
Direct dialling of Haar random unitary matrices
Random unitary matrices find a number of applications in quantum information
science, and are central to the recently defined boson sampling algorithm for
photons in linear optics. We describe an operationally simple method to
directly implement Haar random unitary matrices in optical circuits, with no
requirement for prior or explicit matrix calculations. Our physically-motivated
and compact representation directly maps independent probability density
functions for parameters in Haar random unitary matrices, to optical circuit
components. We go on to extend the results to the case of random unitaries for
qubits
Application of digital particle image velocimetry to insect aerodynamics: measurement of the leading-edge vortex and near wake of a Hawkmoth.
Some insects use leading-edge vortices to generate high lift forces, as has been inferred from qualitative smoke visualisations of the flow around their wings. Here we present the first Digital Particle Image Velocimetry (DPIV) data and quantitative analysis of an insect’s leading-edge vortex and near wake at two flight speeds. This allows us to describe objectively 2D slices through the flow field of a tethered Tobacco Hawkmoth (Manduca sexta). The near-field vortex wake appears to braodly resemble elliptical vortex loops. The presence of a leading-edge vortex towards the end of the downstroke is found to coincide with peak upward force production measured by a six-component force–moment balance. The topology of Manduca’s leading-edge vortex differs from that previously described because late in the downstroke, the structure extends continuously from wingtip across the thorax to the other wingtip
Zero area singularities in general relativity and inverse mean curvature flow
First we restate the definition of a Zero Area Singularity, recently
introduced by H. Bray. We then consider several definitions of mass for these
singularities. We use the Inverse Mean Curvature Flow to prove some new results
about the mass of a singularity, the ADM mass of the manifold, and the capacity
of the singularity.Comment: 13 page
Obituary: Arthur Cruickshank 1932 - 2011. A native Gondwanan, who studied the former continent's fossil tetrapods
Dr Arthur Richard Ivor Cruickshank died
on 4th December 2011, aged 79, in the
Borders General Hospital, Melrose, Scotland.
Arthur Cruickshank was part of the post-war
generation of palaeontologists who laid the
foundations on which today’s researchers
build. Appropriately for someone from
an expatriate Scots family living in Kenya,
much of his work was on the extinct reptiles
of the great southern palaeocontinent of
Gondwana
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