Volunteers and volunteering in leisure : social science perspectives

Leisure has been widely examined within the context of social science theory; however, little work has considered the range of social science disciplines and applied them to specific phenomena located within the leisure field. This paper adopts such an approach to conceptualise and examine volunteers and volunteering in leisure settings. In a disciplinary sense, therefore, the sociological view focuses upon the conceptualisation of volunteering as leisure, the psychological view seeks to understand motivations driving volunteering while the perspective of economists tends to complement these standpoints in terms of why people volunteer and further examines the value of volunteer contributions. Comparative analysis of the perspectives enunciated within these key disciplines provides a picture of the status of research relating to leisure volunteers and volunteering. The purposes of this paper are to identify gaps in current knowledge, drawing out conclusions and their implications for an improved understanding of this area as well as to enhance comprehension of disciplinary contributions to the study of leisure phenomena

Detecting solar chameleons through radiation pressure

Light scalar fields can drive the accelerated expansion of the universe. Hence, they are obvious dark energy candidates. To make such models compatible with tests of General Relativity in the solar system and "fifth force" searches on Earth, one needs to screen them. One possibility is the so-called "chameleon" mechanism, which renders an effective mass depending on the local matter density. If chameleon particles exist, they can be produced in the sun and detected on Earth exploiting the equivalent of a radiation pressure. Since their effective mass scales with the local matter density, chameleons can be reflected by a dense medium if their effective mass becomes greater than their total energy. Thus, under appropriate conditions, a flux of solar chameleons may be sensed by detecting the total instantaneous momentum transferred to a suitable opto-mechanical force/pressure sensor. We calculate the solar chameleon spectrum and the reach in the chameleon parameter space of an experiment using the preliminary results from a force/pressure sensor, currently under development at INFN Trieste, to be mounted in the focal plane of one of the X-Ray telescopes of the CAST experiment at CERN. We show, that such an experiment signifies a pioneering effort probing uncharted chameleon parameter space.Comment: revised versio

Simulation of High-Resolution Magnetic Resonance Images on the IBM Blue Gene/L Supercomputer Using SIMRI

Medical imaging system simulators are tools that provide a means to evaluate system architecture and create artificial image sets that are appropriate for specific applications. We have modified SIMRI, a Bloch equation-based magnetic resonance image simulator, in order to successfully generate high-resolution 3D MR images of the Montreal brain phantom using Blue Gene/L systems. Results show that redistribution of the workload allows an anatomically accurate 2563 voxel spin-echo simulation in less than 5 hours when executed on an 8192-node partition of a Blue Gene/L system

Kinetics of the Multiferroic Switching in MnWO4_4

The time dependence of switching multiferroic domains in MnWO$_4$ has been studied by time-resolved polarized neutron diffraction. Inverting an external electric field inverts the chiral magnetic component within rise times ranging between a few and some tens of milliseconds in perfect agreement with macroscopic techniques. There is no evidence for any faster process in the inversion of the chiral magnetic structure. The time dependence is well described by a temperature-dependent rise time suggesting a well-defined process of domain reversion. As expected, the rise times decrease when heating towards the upper boundary of the ferroelectric phase. However, switching also becomes faster upon cooling towards the lower boundary, which is associated with a first-order phase transition

Spatially resolved spectra of 3C galaxy nuclei

We present and discuss visible-wavelength long-slit spectra of four low redshift 3C galaxies obtained with the STIS instrument on the Hubble Space Telescope. The slit was aligned with near-nuclear jet-like structure seen in HST images of the galaxies, to give unprecedented spatial resolution of the galaxy inner regions. In 3C 135 and 3C 171, the spectra reveal clumpy emission line structures that indicate outward motions of a few hundred km s$^{-1}$ within a centrally illuminated and ionised biconical region. There may also be some low-ionisation high-velocity material associated with 3C 135. In 3C 264 and 3C 78, the jets have blue featureless spectra consistent with their proposed synchrotron origin. There is weak associated line emission in the innermost part of the jets with mild outflow velocity. These jets are bright and highly collimated only within a circumnuclear region of lower galaxy luminosity, which is not dusty. We discuss the origins of these central regions and their connection with relativistic jets.Comment: 15 pages incl Tables, 12 diagrams, To appear in A

Weak distinction and the optimal definition of causal continuity

Causal continuity is usually defined by imposing the conditions (i) distinction and (ii) reflectivity. It is proved here that a new causality property which stays between weak distinction and causality, called feeble distinction, can actually replace distinction in the definition of causal continuity. An intermediate proof shows that feeble distinction and future (past) reflectivity implies past (resp. future) distinction. Some new characterizations of weak distinction and reflectivity are given.Comment: 9 pages, 2 figures. v2: improved and expanded version. v3: a few misprints have been corrected and a reference has been update

Long term preservation of DNA from honey bees (Apis mellifera) collected in aerial pitfall traps

This study examines the preservation of nuclear and mitochondrial DNA from honey bee (Apis mellifera L.) specimens which were first kept in propylene glycol-based antifreeze under various conditions, and then stored long-term, refrigerated in 95% ethanol. Two sets of bees were subjected to the propylene glycol treatment, then ethanol storage. One set consisted of bees captured in the field in propylene glycol-containing "aerial pitfall traps", where they remained for up to 21 days. A second set consisted of bees taken from a hive and kept in propylene glycol under various temperature and lighting conditions for up to 90 days. Both the field bees and laboratory bees were then stored long-term in ethanol before evaluation of the persistence of nuclear and mitochondrial DNA using the polymerase chain reaction. DNA integrity was preserved for both field and laboratory specimens. The results demonstrate that propylene glycol-captured, ethanol-preserved honey bees retain both nuclear and mitochondrial DNA after capture and long tern preservation. It is suggested that with little or no modification, the techniques described here might he applied to other studies involving trap-collected arthropod specimens

Production of J/ψJ/\psi-pairs at HERA-N⃗\vec{{\rm N}}

The production of $J/\psi$-pairs as a possible measure of the polarized gluon distribution $\Delta G(x)$ is studied for proton--nucleon collisions at \sqrt{s} =40\;\mbox{GeV}^2 (HERA-$\vec{{\rm N}}$). Possibilities of reconstructing the helicity state of at least one of the $J/\psi$'s are critically reviewed. The observation of production asymmetries in the single polarized mode of HERA-$\vec{{\rm N}}$ is found to be not feasible.Comment: 8 pages, LATeX, 3 figures availabe as .uu-fil