69,530 research outputs found
Degrees of permeability: confinement, power and resistance in Freetown's Central Prison
This article deconstructs a binary that has arisen between prisons as, on the one hand, ‘total institutions’ of exclusion and, on the other, ‘carceral continuums’ that incorporate marginalized urban livelihoods. The experiences of four inmates at Pademba Road, Freetown’s male prison – which accommodates inmates with sentences from one year to life – illustrate that prisons belong in neither camp. Instead, inmates’ unique responses to their imprisonment show that both a prison’s continuity and its exclusionary mechanism are situational and gendered as crime, social standing, capital and agency coalesce. Following Michel de Certeau’s examination of people’s reappropriations of culture in everyday life, this article analyses how inmates’ tactics to reinforce and bend prison walls work to either strengthen or undermine the carceral system’s strategies and influence the prison’s permeability. Inmates’ embodied experiences allow for a nuanced understanding of the inside/outside relationship of imprisonment and of the space between mobility and stasis, subjugation, embrace and resistance.</jats:p
Maximum Entropy Distributions Inferred from Option Portfolios on an Asset
We obtain the maximum entropy distribution for an asset from call and digital
option prices. A rigorous mathematical proof of its existence and exponential
form is given, which can also be applied to legitimise a formal derivation by
Buchen and Kelly. We give a simple and robust algorithm for our method and
compare our results to theirs. We present numerical results which show that our
approach implies very realistic volatility surfaces even when calibrating only
to at-the-money options. Finally, we apply our approach to options on the S&P
500 index.Comment: 23 pages, 5 figures, to appear in Finance and Stochastic
Pressure and isotope effect on the anisotropy of MgB
We analyze the data for the pressure and boron isotope effect on the
temperature dependence of the magnetization near . Invoking the
universal scaling relation for the magnetization at fixed magnetic field it is
shown that the relative shift of , induced by pressure or boron isotope
exchange, mirrors essentially that of the anisotropy. This uncovers a novel
generic property of anisotropic type II superconductors, inexistent in the
isotropic case. For MgB it implies that the renormalization of the Fermi
surface topology due to pressure or isotope exchange is dominated by a
mechanism controlling the anisotropy.Comment: 7 pages, 3 figure
A Climatology of the Tropospheric Thermal Stratification Using Saturation Potential Vorticity
The condition of convective neutrality is assessed in the troposphere by calculating the saturation potential vorticity P* from reanalysis data. Regions of the atmosphere in which saturation entropy is constant along isosurfaces of absolute angular momentum, a state indicative of slantwise-convective neutrality, have values of P* equal to zero. In a global reanalysis dataset spanning the years 1970–2004, tropospheric regions are identified in which P* is near zero, implying that vertical convection or slantwise convection may be important in determining the local thermal stratification. Convectively neutral air masses are common not only in the Tropics but also in higher latitudes, for example, over midlatitude continents in summer and in storm tracks over oceans in winter. Large-scale eddies appear to stabilize parts of the lower troposphere, particularly in winter
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The Domestic Politics of International Cooperation: Germany and the European Debt Crisis
Coexistence between fluid and crystalline phases of proteins in photosynthetic membranes
Photosystem II (PSII) and its associated light-harvesting complex II (LHCII)
are highly concentrated in the stacked grana regions of photosynthetic
thylakoid membranes. Within the membrane, PSII-LHCII supercomplexes can be
arranged in disordered packings, ordered arrays, or mixtures thereof. The
physical driving forces underlying array formation are unknown, complicating
attempts to determine a possible functional role for arrays in regulating light
harvesting or energy conversion efficiency. Here we introduce a coarse-grained
model of protein interactions in coupled photosynthetic membranes, focusing on
just two particle types that feature simple shapes and potential energies
motivated by structural studies. Reporting on computer simulations of the
model's equilibrium fluctuations, we demonstrate its success in reproducing
diverse structural features observed in experiments, including extended
PSII-LHCII arrays. Free energy calculations reveal that the appearance of
arrays marks a phase transition from the disordered fluid state to a
system-spanning crystal, which can easily be arrested by thermodynamic
constraints or slow dynamics. The region of fluid-crystal coexistence is broad,
encompassing much of the physiologically relevant parameter regime. Our results
suggest that grana membranes lie at or near phase coexistence, conferring
significant structural and functional flexibility to this densely packed
membrane protein system.Comment: 11 pages, 5 figure
The Tail of the HI Mass Function
The contribution of extragalactic objects with HI masses below
to the HI mass function remains uncertain. Several aspects of the detection of
low-mass sources in HI surveys are not always considered, and as a result
different analysis techniques yield widely different estimates for their number
density. It is suggested at one extreme that the number density of galaxies
follows a shallow Schechter power-law slope, and at the other extreme that it
follows a steep faint-end rise like that found for field optical sources. Here
we examine a variety of selection effects, issues of completeness, and
consequences of LSS. We derive results for the large Arecibo Dual Beam Survey
which indicate that the field mass function does rise steeply, while within the
Virgo Cluster environs, the slope appears to be much shallower. Dependence on
the local density of galaxies may partially explain differences between
surveys.Comment: 8 pages, presented at Mapping the Hidden Universe: The Universe in
HI. eds Kraan-Korteweg, Henning, Andernac
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