1,006 research outputs found
Uncovering subjective perceptions of Chinese economic development through ethnographic research – A business anthropologist’s notes from the field.
Economic change in China will move hundreds of millions of households from poverty to prosperity. But what does everyday life look like for a Chinese family living through Chinese economic development? As a consultant and ethnographer working for ReD Associates I’d like to share some intimate experiences from my research with a middle-class man who has lived through the country’s transformation
Turbulent Chemical Diffusion in Convectively Bounded Carbon Flames
It has been proposed that mixing induced by convective overshoot can disrupt
the inward propagation of carbon deflagrations in super-asymptotic giant branch
stars. To test this theory, we study an idealized model of convectively bounded
carbon flames with 3D hydrodynamic simulations of the Boussinesq equations
using the pseudospectral code Dedalus. Because the flame propagation timescale
is much longer than the convection timescale, we approximate the flame as fixed
in space, and only consider its effects on the buoyancy of the fluid. By
evolving a passive scalar field, we derive a {\it turbulent} chemical
diffusivity produced by the convection as a function of height, .
Convection can stall a flame if the chemical mixing timescale, set by the
turbulent chemical diffusivity, , is shorter than the flame
propagation timescale, set by the thermal diffusivity, , i.e., when
. However, we find for most of the flame
because convective plumes are not dense enough to penetrate into the flame.
Extrapolating to realistic stellar conditions, this implies that convective
mixing cannot stall a carbon flame and that "hybrid carbon-oxygen-neon" white
dwarfs are not a typical product of stellar evolution.Comment: Accepted to Ap
Titan imagery with Keck adaptive optics during and after probe entry
We present adaptive optics data from the Keck telescope, taken while the Huygens probe descended through Titan's atmosphere and on the days following touchdown. No probe entry signal was detected. Our observations span a solar phase angle range from 0.05° up to 0.8°, with the Sun in the west. Contrary to expectations, the east side of Titan's stratosphere was usually brightest. Compiling images obtained with Keck and Gemini over the past few years reveals that the east-west asymmetry can be explained by a combination of the solar phase angle effect and an enhancement in the haze density on Titan's morning hemisphere. While stratospheric haze was prominent over the northern hemisphere, tropospheric haze dominated the south, from the south pole up to latitudes of ∼45°S. At 2.1 μm this haze forms a polar cap, while at 1.22 μm it appears in the form of a collar at 60°S. A few small clouds were usually present near the south pole, at altitudes of 30–40 km. Our narrowband J,H,K images of Titan's surface compare extremely well with that obtained by Cassini ISS, down to the small-scale features. The surface contrast between dark and bright areas may be larger at 2 μm than at 1.6 and 1.3 μm, which would imply that the dark areas may be covered by a coarser-grained frost than the bright regions and/or that there is additional 2 μm absorption there
The Metropolis and Evangelical Life: Coherence and Fragmentation in the ‘Lost City of London’
This article examines the interplay of different processes of cultural and subjective fragmentation experienced by conservative evangelical Anglicans, based on an ethnographic study of a congregation in central London. The author focuses on the evangelistic speaking practices of members of this church to explore how individuals negotiate contradictory norms of interaction as they move through different city spaces, and considers their response to tensions created by the demands of their workplace and their religious lives. Drawing on Georg Simmel’s ‘The Metropolis and Mental Life’, the author argues that their faith provides a sense of coherence and unity that responds to experiences of cultural fragmentation characteristic of everyday life in the city, while simultaneously leading to a specific consciousness of moral fragmentation that is inherent to conservative evangelicalism
Numerical Simulations of Internal Wave Generation by Convection in Water
Water's density maximum at 4C makes it well suited to study internal gravity
wave excitation by convection: an increasing temperature profile is unstable to
convection below 4C, but stably stratified above 4C. We present numerical
simulations of a water-like fluid near its density maximum in a two dimensional
domain. We successfully model the damping of waves in the simulations using
linear theory, provided we do not take the weak damping limit typically used in
the literature. In order to isolate the physical mechanism exciting internal
waves, we use the novel spectral code Dedalus to run several simplified model
simulations of our more detailed simulation. We use data from the full
simulation as source terms in two simplified models of internal wave excitation
by convection: bulk excitation by convective Reynolds stresses, and interface
forcing via the mechanical oscillator effect. We find excellent agreement
between the waves generated in the full simulation and the simplified
simulation implementing the bulk excitation mechanism. The interface forcing
simulations over excite high frequency waves because they assume the excitation
is by the "impulsive" penetration of plumes, which spreads energy to high
frequencies. However, we find the real excitation is instead by the "sweeping"
motion of plumes parallel to the interface. Our results imply that the bulk
excitation mechanism is a very accurate heuristic for internal wave generation
by convection.Comment: Accepted to PR
The Convex Body Isoperimetric Conjecture in the Plane
The Convex Body Isoperimetric Conjecture states that the least perimeter needed to enclose a volume within a ball is greater than the least perimeter needed to enclose the same volume within any other convex body of the same volume in Rn. We focus on the conjecture in the plane and prove a new sharp lower bound for the isoperimetric profile of the disk in this case. We prove the conjecture in the case of regular polygons, and show that in a general planar convex body the conjecture holds for small areas
“Halal fiction” and the limits of postsecularism: Criticism, critique, and the Muslim in Leila Aboulela’s Minaret
This article examines Leila Aboulela’s 2005 novel Minaret, considering the extent to which it can be seen as an example of a postsecular text. The work has been praised by some as one of the most cogent attempts to communicate a life of Islamic faith in the English language novel form. Others have expressed concern about what they perceive as its apparent endorsement of submissiveness and a secondary status for women, along with its silence on some of the more thorny political issues facing Islam in the modern world. I argue that both these readings are shaped by the current “market” for Muslim novels, which places on such texts the onus of being “authentically representative”. Moreover, while apparently underwriting claims to authenticity, Aboulela’s technique of unvarnished realism requires of the reader the kind of suspension of disbelief in the metaphysical that appears to run contrary to the secular trajectory of the English literary novel in the last 300 years. I take issue with binarist versions of the postsecular thesis that equate the post-Enlightenment West with relentless desacralization and the “Islamic world” with a persistent collectivist and spiritual outlook, and suggest that we pay more attention to fundamental narrative elements which recur across the supposed West/East divide. Historically simplistic understandings of the secularization of culture — followed in the last few years by a postsecular turn — misrepresent the actual evolution of the novel. The “religious” persists, albeit transmuted into symbolic schema and themes of material or emotional redemption. I end by arguing for the renewed relevance of the kind of analysis of literary “archetypes” suggested by Northrop Frye, albeit disentangled from its specifically Christian resonances and infused by more attention to cultural cross-pollination. It is this type of approach that seems more accurately to account for the peculiarities of Aboulela’s fiction
Unitarity Bounds in AdS_3 Higher Spin Gravity
We study SL(N,R) Chern-Simons gauge theories in three dimensions. The choice
of the embedding of SL(2,R) in SL(N,R), together with asymptotic boundary
conditions, defines a theory of higher spin gravity. Each inequivalent
embedding leads to a different asymptotic symmetry group, which we map to an
OPE structure at the boundary. A simple inspection of these algebras indicates
that only the W_N algebra constructed using the principal embedding could admit
a unitary representation for large values of the central charge.Comment: 1+23 pages, Version 3 Appendix B revise
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