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 $g(r)$, 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