Public Recreation and Neighborhood Sense of Community: An Exploration of a Hypothesized Relationship

This study explores the relationship between park attributes (perceived safety and perceived benefits) and their relationship to sense of community in urban neighborhoods. The study finds that the perception of benefits derived from park use has a direct relationship with sense of community, and that park safety is indirectly related to sense of community, with the perception of park benefits mediating the relationship between park safety and sense of community. Theoretical and practical considerations are discussed

Dans l'ombre du dictateur : l’élite politique chinoise à l'ère de Xi Jinping

Le président Xi Jinping est probablement le dirigeant chinois le plus puissant depuis Mao Zedong. La récente révision constitutionnelle et le remaniement de la direction politique intervenus à mi-mandat ont encore alimenté la crainte que Xi, à l'instar de Mao, n'ait aucune intention de transmettre le pouvoir à un futur successeur. L'ascension de Xi est-elle le signe de la fin de la direction collective ? Un président plus puissant entraînera-t-il l'affaiblissement du Parti ? Dans le présent article, nous examinons les méthodes employées par Xi pour consolider son pouvoir ainsi que les conséquences futures qu'un tel changement pourrait entraîner pour l'élite politique chinoise. En comparant plusieurs sources académiques, nous interrogeons le jeu à somme nulle qui régit la relation entre le pouvoir personnel et la force institutionnelle. Bien que Xi ait sans conteste concentré un pouvoir personnel sans précédent, cela ne s'est pas nécessairement fait aux dépens du Parti. Les dangers liés à la position de force de Xi Jinping sont plutôt à chercher du côté de son effet dissuasif sur l'expression des avis divergents et sur la réduction du vivier de futurs dirigeants, deux conséquences susceptibles d'affaiblir la capacité à gouverner sur les moyen et long termes

Dictator’s Shadow

President Xi Jinping is arguably the most powerful Chinese leader since Chairman Mao. Recent constitutional revisions and a midterm leadership reshuffle has only substantiated the fear that Xi, like Mao, has no intention of handing over power to a future successor. Does Xi’s rise signal an end to collective leadership and does a stronger president translate into a weaker party? In this article, I review the methods by which Xi has come to consolidate power as well as the implications for Chinese elite politics in the future. Drawing insights from the comparative literature, I question the zero-sum relationship between executive and institutional strength. Although Xi has certainly amassed unprecedented personal power, it has not necessarily come at the expense of the Party. Instead, the dangers of Xi Jinping’s power grab are more likely to result from a chilling effect on dissenting opinions and thinning out of the leadership pipeline, each of which is likely to undermine governing capacity over the medium to long-term

Touch uses frictional cues to discriminate flat materials

In a forced-choice task, we asked human participants to discriminate by touch alone glass plates from transparent polymethyl methacrylate (PMMA) plastic plates. While the surfaces were flat and did not exhibit geometric features beyond a few tens of nanometres, the materials differed by their molecular structures. They produced similar coefficients of friction and thermal effects were controlled. Most participants performed well above chance and participants with dry fingers discriminated the materials especially well. Current models of tactile surface perception appeal to surface topography and cannot explain our results. A correlation analysis between detailed measurements of the interfacial forces and discrimination performance suggested that the perceptual task depended on the transitory contact phase leading to full slip. This result demonstrates that differences in interfacial mechanics between the finger and a material can be sensed by touch and that the evanescent mechanics that take place before the onset of steady slip have perceptual value

Implant augmentation: Adding bone cement to improve the treatment of osteoporotic distal femur fractures:A biomechanical study using human cadaver bones

The increasing problems in the field of osteoporotic fracture fixation results in specialized implants as well as new operation methods, for example, implant augmentation with bone cement. The aim of this study was to determine the biomechanical impact of augmentation in the treatment of osteoporotic distal femur fractures. Seven pairs of osteoporotic fresh frozen distal femora were randomly assigned to either an augmented or nonaugmented group. In both groups, an Orthopaedic Trauma Association 33 A3 fractures was fixed using the locking compression plate distal femur and cannulated and perforated screws. In the augmented group, additionally, 1 mL of polymethylmethacrylate cement was injected through the screw. Prior to mechanical testing, bone mineral density (BMD) and local bone strength were determined. Mechanical testing was performed by cyclic axial loading (100 N to 750 N + 0.05N/cycle) using a servo-hydraulic testing machine. As a result, the BMD as well as the axial stiffness did not significantly differ between the groups. The number of cycles to failure was significantly higher in the augmented group with the BMD as a significant covariate. In conclusion, cement augmentation can significantly improve implant anchorage in plating of osteoporotic distal femur fractures

A mixed-mode shell-model theory for nuclear structure studies

We introduce a shell-model theory that combines traditional spherical states, which yield a diagonal representation of the usual single-particle interaction, with collective configurations that track deformations, and test the validity of this mixed-mode, oblique basis shell-model scheme on $^{24}$Mg. The correct binding energy (within 2% of the full-space result) as well as low-energy configurations that have greater than 90% overlap with full-space results are obtained in a space that spans less than 10% of the full space. The results suggest that a mixed-mode shell-model theory may be useful in situations where competing degrees of freedom dominate the dynamics and full-space calculations are not feasible.Comment: 20 pages, 8 figures, revtex 12p

Design and Applications of Multi-Frequency Holographic Subsurface Radar: Review and Case Histories

Holographic subsurface radar (HSR) is not currently in widespread usage. This is due to a historical perspective in the ground-penetrating radar (GPR) community that the high attenuation of electromagnetic waves in most media of interest and the inability to apply time-varying gain to the continuous-wave (CW) HSR signal preclude sufficient effective penetration depth. While it is true that the fundamental physics of HSR, with its use of a CW signal, does not allow amplification of later (i.e., deeper) arrivals in lossy media (as is possible with impulse subsurface radar (ISR)), HSR has distinct advantages. The most important of these is the ability to do shallow subsurface imaging with a resolution that is not possible with ISR. In addition, the design of an HSR system is simpler than for ISR due to the relatively low-tech transmitting and receiving antennae. This paper provides a review of the main principles of HSR through an optical analogy and describes possible algorithms for radar hologram reconstruction. We also present a review of the history of development of systems and applications of the RASCAN type, which is possibly the only commercially available holographic subsurface radar. Among the subsurface imaging and remote sensing applications considered are humanitarian demining, construction inspection, nondestructive testing of dielectric aerospace materials, surveys of historic architecture and artworks, paleontology, and security screening. Each application is illustrated with relevant data acquired in laboratory and/or field experiments

Deformations of the fermion realization of the sp(4) algebra and its subalgebras

With a view towards future applications in nuclear physics, the fermion realization of the compact symplectic sp(4) algebra and its q-deformed versions are investigated. Three important reduction chains of the sp(4) algebra are explored in both the classical and deformed cases. The deformed realizations are based on distinct deformations of the fermion creation and annihilation operators. For the primary reduction, the su(2) sub-structure can be interpreted as either the spin, isospin or angular momentum algebra, whereas for the other two reductions su(2) can be associated with pairing between fermions of the same type or pairing between two distinct fermion types. Each reduction provides for a complete classification of the basis states. The deformed induced u(2) representations are reducible in the action spaces of sp(4) and are decomposed into irreducible representations.Comment: 28 pages, LaTeX 12pt article styl