The Impact of Greenspace, Walking, and Cycling on the Health of Urban Residents during the COVID-19 Pandemic: A Study of London

Vulnerability to COVID-19 has been linked to public health issues like obesity and physical fitness, which consecutively can be linked to access to urban greenspace. However, the value of greenspaces remains contentious in the literature and unclear in practice. In view of very high COVID-19 mortality rates, we use data from London boroughs to explore the impact of green infrastructure in terms of the size, accessibility, and support of physical activity and healthy lifestyles (e.g., walking and cycling). Results show no significant relationship between the availability of greenspace and the probability of being obese or dying from COVID-19. Cycling once, thrice, or five times weekly was found to improve healthy weight, as does cycling once a month. However, the probability of dying from COVID-19 during lockdowns is correlated to the frequency of walking or cycling as a result of decreased social distancing, while the frequency of walking and cycling is determined by availability and access to greenspace

Introduction to the Special Issue, Everyday Self-Employment

A ‘partial renaissance’ of self-employment in labor markets of the global North has attracted policy concern across national, supranational and global scales, yet sociological thought has been somewhat slower to respond to this phenomenon. In response, this special issue focuses on everyday self-employment amongst workers drawn from countries across the world. The collection of articles in this volume originated, in part, from a recent symposium that took place at City, University of London, which highlighted the contribution of sociology and cognate disciplines to the study of self-employment. The volume considers the social and structural forces that condition this economic activity as an ideology and practice, as well as the constraints and opportunities for its maintenance and reproduction. It also examines the everyday lives of self-employed workers and in particular the ways in which self-employment is experienced across a range of geographical, occupational, and industrial contexts, and with regard to social categories including race, class, nationality and gender. As neo-liberal subjects we are increasingly required to inhabit an entrepreneurial self. As such, a sociological understanding of the global patterns and everyday experiences of self-employment – or entrepreneurialism as practice – is essential for a critical understanding of the economy and society and the cultural legitimations associated with this oft-celebrated and aspirational economic activity. The contributors in this volume often challenge the mainstream view of self-employment and entrepreneurship to reveal the complexity and scope of activity; their perspectives provide new insights for researchers and policymakers regarding the function of self-employment in a changing economy and society. This introduction initiates a discussion of the central debates in the study of self-employment, introduces a working conceptualization of self-employment, and presents a brief synopsis of the articles in this volume

NMR evidence for Friedel-like oscillations in the CuO chains of ortho-II YBa2_2Cu3_3O6.5_{6.5}

Nuclear magnetic resonance (NMR) measurements of CuO chains of detwinned Ortho-II YBa$_2$Cu$_3$O$_{6.5}$ (YBCO6.5) single crystals reveal unusual and remarkable properties. The chain Cu resonance broadens significantly, but gradually, on cooling from room temperature. The lineshape and its temperature dependence are substantially different from that of a conventional spin/charge density wave (S/CDW) phase transition. Instead, the line broadening is attributed to small amplitude static spin and charge density oscillations with spatially varying amplitudes connected with the ends of the finite length chains. The influence of this CuO chain phenomenon is also clearly manifested in the plane Cu NMR.Comment: 4 pages, 3 figures, refereed articl

Exact Computation of Influence Spread by Binary Decision Diagrams

Evaluating influence spread in social networks is a fundamental procedure to estimate the word-of-mouth effect in viral marketing. There are enormous studies about this topic; however, under the standard stochastic cascade models, the exact computation of influence spread is known to be #P-hard. Thus, the existing studies have used Monte-Carlo simulation-based approximations to avoid exact computation. We propose the first algorithm to compute influence spread exactly under the independent cascade model. The algorithm first constructs binary decision diagrams (BDDs) for all possible realizations of influence spread, then computes influence spread by dynamic programming on the constructed BDDs. To construct the BDDs efficiently, we designed a new frontier-based search-type procedure. The constructed BDDs can also be used to solve other influence-spread related problems, such as random sampling without rejection, conditional influence spread evaluation, dynamic probability update, and gradient computation for probability optimization problems. We conducted computational experiments to evaluate the proposed algorithm. The algorithm successfully computed influence spread on real-world networks with a hundred edges in a reasonable time, which is quite impossible by the naive algorithm. We also conducted an experiment to evaluate the accuracy of the Monte-Carlo simulation-based approximation by comparing exact influence spread obtained by the proposed algorithm.Comment: WWW'1

Central mode and spin confinement near the boundary of the superconducting phase in YBa2Cu3O6.353 (Tc=18 K)

We have mapped the neutron scattering spin spectrum at low-energies in YBa2Cu3O6.353 (Tc=18 K) where the doping ~0.06 is near the critical value (pc=0.055) for superconductivity. No coexistence with long range ordered antiferromagnetism is found. The spins fluctuate on two energy scales, one a damped spin response with a ~2 meV relaxation rate and the other a central mode with a relaxation rate that slows to less than 0.08 meV below Tc. The spectrum mirrors that of a soft mode driving a central mode. Extremely short correlation lengths, 42+-5 Angstrom in-plane and 8+-2 Angstrom along the c direction, and isotropic spin orientations for the central mode indicate that the correlations are subcritical with respect to any second order transition to Neel order. The dynamics follows a model where damped spin fluctuations are coupled to the slow fluctuations of regions with correlations shortened by the hole doping.Comment: 5 pages 4 figures. One figure revised and some text revision. Accepted PRB Rapids February 14, 200