1,974 research outputs found
Social centres and the new cooperativism of the common
In recent years a network of self-managed social centres has been spreading across the UK and further afield. They take their inspiration from an array of previous experiments in autonomous space, including the centri sociali in Italy and the Autonome squats of Germany and the Netherlands. This article looks at several examples of social centres, based on interviews and online responses with participants, as well as the author’s own involvement in social centres. At the heart of these spaces are principles of autonomy and collective struggle. This article argues that they represent examples of the production of “new commons,” and as such are an important demonstration of self-management and the “new cooperativism” in practice
Quantum lost property: a possible operational meaning for the Hilbert-Schmidt product
Minimum error state discrimination between two mixed states \rho and \sigma
can be aided by the receipt of "classical side information" specifying which
states from some convex decompositions of \rho and \sigma apply in each run. We
quantify this phenomena by the average trace distance, and give lower and upper
bounds on this quantity as functions of \rho and \sigma. The lower bound is
simply the trace distance between \rho and \sigma, trivially seen to be tight.
The upper bound is \sqrt{1 - tr(\rho\sigma)}, and we conjecture that this is
also tight. We reformulate this conjecture in terms of the existence of a pair
of "unbiased decompositions", which may be of independent interest, and prove
it for a few special cases. Finally, we point towards a link with a notion of
non-classicality known as preparation contextuality.Comment: 3 pages, 1 figure. v2: Less typos in text and less punctuation in
titl
Properties of cage rearrangements observed near the colloidal glass transition
We use confocal microscopy to study the motions of particles in concentrated
colloidal systems. Near the glass transition, diffusive motion is inhibited, as
particles spend time trapped in transient ``cages'' formed by neighboring
particles. We measure the cage sizes and lifetimes, which respectively shrink
and grow as the glass transition approaches. Cage rearrangements are more
prevalent in regions with lower local concentrations and higher disorder.
Neighboring rearranging particles typically move in parallel directions,
although a nontrivial fraction move in anti-parallel directions, usually from
pairs of particles with initial separations corresponding to the local maxima
and minima of the pair correlation function , respectively.Comment: 5 pages, 4 figures; text & figures revised in v
Equilibrium phase behavior of polydisperse hard spheres
We calculate the phase behavior of hard spheres with size polydispersity,
using accurate free energy expressions for the fluid and solid phases. Cloud
and shadow curves, which determine the onset of phase coexistence, are found
exactly by the moment free energy method, but we also compute the complete
phase diagram, taking full account of fractionation effects. In contrast to
earlier, simplified treatments we find no point of equal concentration between
fluid and solid or re-entrant melting at higher densities. Rather, the fluid
cloud curve continues to the largest polydispersity that we study (14%); from
the equilibrium phase behavior a terminal polydispersity can thus only be
defined for the solid, where we find it to be around 7%. At sufficiently large
polydispersity, fractionation into several solid phases can occur, consistent
with previous approximate calculations; we find in addition that coexistence of
several solids with a fluid phase is also possible
Neoliberalism and Depoliticisation in the Academy: Understanding the ‘New Student Rebellions’
Since 2009 there has been an upsurge in political activity in and around the UK, as well as in some European and American universities. These ‘new student rebellions’ have displayed levels of radicalism and po- litical activism seemingly unprecedented among recent generations of students. Broadly speaking, the intensification of this activity can be understood as being directly related to ongoing neoliberal reforms of education, a process intensified by the global financial crisis. In this article we seek to consider some of the detail of the emergence of these rebellions, and argue that they can be interpreted as part of resistance to the neoliberal tendencies in contemporary social life. As such, we argue that a depoliticised tendency accompanies the introduc- tion of, and resistance to, neoliberal mechanisms in Higher Education (HE). As activists in groups who have adopted more creative and ex- plicitly politically antagonistic forms of activism, we suggest that such forms might be more productive arenas for our energies if we want to challenge the neoliberal and depoliticised root causes of these con- flicts
Transforming the university: Beyond students and cuts
Much has been made of the recent upsurge in activism around higher education and universities over the past two years or so in the UK and globally. Reflecting on our involvement with a group called the Really Open University (ROU) in Leeds, in this article we seek to broaden the discussion of the 'student movement' to consider some of the tensions that exist between mainstream analyses of the student movement and those analyses which acknowledge the problems with trying merely to defend the university in its current form. We outline some of the emerging links between groups which seek to move beyond a narrow, reactive politics of 'anti-cuts' by challenging the forms and futures of education. The tensions of trying to be at once 'in-against-and-beyond' the institutions we are involved with are considered, and it is our conclusion that within the ROU's 'Strike/Occupy/Transform' motif it is the notion of transformation, accompanied by the necessary resistance, which offers the most hope for the future of education
Dynamics of hard-sphere suspension using Dynamic Light Scattering and X-Ray Photon Correlation Spectroscopy: dynamics and scaling of the Intermediate Scattering Function
Intermediate Scattering Functions (ISF's) are measured for colloidal hard
sphere systems using both Dynamic Light Scattering (DLS) and X-ray Photon
Correlation Spectroscopy (XPCS). We compare the techniques, and discuss the
advantages and disadvantages of each. Both techniques agree in the overlapping
range of scattering vectors. We investigate the scaling behaviour found by
Segre and Pusey [1] but challenged by Lurio et al. [2]. We observe a scaling
behaviour over several decades in time but not in the long time regime.
Moreover, we do not observe long time diffusive regimes at scattering vectors
away from the peak of the structure factor and so question the existence of a
long time diffusion coefficients at these scattering vectors.Comment: 21 pages, 11 figure
From random walk to single-file diffusion
We report an experimental study of diffusion in a quasi-one-dimensional (q1D)
colloid suspension which behaves like a Tonks gas. The mean squared
displacement as a function of time is described well with an ansatz
encompassing a time regime that is both shorter and longer than the mean time
between collisions. This ansatz asserts that the inverse mean squared
displacement is the sum of the inverse mean squared displacement for short time
normal diffusion (random walk) and the inverse mean squared displacement for
asymptotic single-file diffusion (SFD). The dependence of the single-file 1D
mobility on the concentration of the colloids agrees quantitatively with that
derived for a hard rod model, which confirms for the first time the validity of
the hard rod SFD theory. We also show that a recent SFD theory by Kollmann
leads to the hard rod SFD theory for a Tonks gas.Comment: 4 pages, 4 figure
- …