Critique of proposed limit to space--time measurement, based on Wigner's clocks and mirrors

Based on a relation between inertial time intervals and the Riemannian curvature, we show that space--time uncertainty derived by Ng and van Dam implies absurd uncertainties of the Riemannian curvature.Comment: 5 pages, LaTex, field "Author:" correcte

Climatic control on the peak discharge of glacier outburst floods

Lakes impounded by natural ice dams occur in many glacier regions. Their sudden emptying along subglacial paths can unleash similar to 1 km(3) of floodwater, but predicting the peak discharge of these subglacial outburst floods ('jokulhlaups') is notoriously difficult. To study how environmental factors control jokulhlaup magnitude, we use thermo- mechanical modelling to interpret a 40- year flood record from Merzbacher Lake in the Tian Shan. We show that the mean air temperature during each flood modulates its peak discharge, by influencing both the rate of meltwater input to the lake as it drains, and the lake- water temperature. The flood devastation potential thus depends sensitively on weather, and this dependence explains how regional climatic warming drives the rising trend of peak discharges in our dataset. For other subaerial ice- dammed lakes worldwide, regional warming will also promote higher- impact jokulhlaups by raising the likelihood of warm weather during their occurrence, unless other factors reduce lake volumes at flood initiation to outweigh this effect

Validation of the English and Chinese versions of the Quick-FLIC quality of life questionnaire.

A useful measure of quality of life should be easy and quick to complete. Recently, we reported the development and validation of a shortened Chinese version of the Functional Living Index-Cancer (FLIC), which we called the Quick-FLIC. In the present study of 327 English-speaking and 221 Chinese-speaking cancer patients, we validated the English version of the Quick-FLIC and further assessed the Chinese version. The 11 Quick-FLIC items were administered alongside the 11 remaining items of the full FLIC, but there appeared to be little context effect. Validity of the English version of the Quick-FLIC was attested by its strong correlation with two other measures of quality of life, and its ability to detect differences between patients with different performance status and treatment status (each P<0.001). Its internal consistency (alpha=0.86) and test-retest reliability (intraclass correlation=0.76) were also satisfactory. The measure was responsive to changes in performance status (P<0.001). The Chinese version showed similar characteristics. The Quick-FLIC behaved in ways that are highly comparable with the FLIC, even though the Quick-FLIC comprised only 11 items whereas the FLIC comprised 22. Further research is required to see whether the use of shorter instruments can improve data quality and response rates, but the fact that shorter instruments place less burden on the patients is itself inherently important

Graphene-polyelectrolyte multilayer membranes with tunable structure and internal charge

One great advantage of graphene-polyelectrolyte multilayer (GPM) membranes is their tunable structure and internal charge for improved separation performance. In this study, we synthesized GO-dominant GPM membrane with internal negatively-charged domains, polyethyleneimine (PEI)-dominant GPM membrane with internal positively-charged domains and charge-balanced dense/loose GPM membranes by simply adjusting the ionic strength and pH of the GO and PEI solutions used in layer-by-layer membrane synthesis. A combined system of quartz crystal microbalance with dissipation (QCM-D) and ellipsometry was used to analyze the mass deposition, film thickness, and layer density of the GPM membranes. The performance of the GPM membranes were compared in terms of both permeability and selectivity to determine the optimal membrane structure and synthesis strategy. One effective strategy to improve the GPM membrane permeability-selectivity tradeoff is to assemble charge-balanced dense membranes under weak electrostatic interactions. This balanced membrane exhibits the highest MgCl2 selectivity (∼86%). Another effective strategy for improved cation removal is to create PEI-dominant membranes that provide internal positively-charged barrier to enhance cation selectivity without sacrificing water permeability. These findings shine lights on the development of a systematic approach to push the boundary of permeability-selectivity tradeoff for GPM membranes

Radio Polarization Observations of the Snail: A Crushed Pulsar Wind Nebula in G327.1-1.1 with a Highly Ordered Magnetic Field

Pulsar wind nebulae (PWNe) are suggested to be acceleration sites of cosmic rays in the Galaxy. While the magnetic field plays an important role in the acceleration process, previous observations of magnetic field configurations of PWNe are rare, particularly for evolved systems. We present a radio polarization study of the "Snail" PWN inside the supernova remnant G327.1-1.1 using the Australia Telescope Compact Array. This PWN is believed to have been recently crushed by the supernova (SN) reverse shock. The radio morphology is composed of a main circular body with a finger-like protrusion. We detected a strong linear polarization signal from the emission, which reflects a highly ordered magnetic field in the PWN and is in contrast to the turbulent environment with a tangled magnetic field generally expected from hydrodynamical simulations. This could suggest that the characteristic turbulence scale is larger than the radio beam size. We built a toy model to explore this possibility, and found that a simulated PWN with a turbulence scale of about one-eighth to one-sixth of the nebula radius and a pulsar wind filling factor of 50--75% provides the best match to observations. This implies substantial mixing between the SN ejecta and pulsar wind material in this system.Comment: 13 pages, 10 figures, Accepted for publication in Ap

Energy and Mass Generation

Modifications in the energy momentum dispersion laws due to a noncommutative geometry, have been considered in recent years. We examine the oscillations of extended objects in this perspective and find that there is now a "generation" of energy.Comment: 13 pages Late

Hegemonic conceptualizations of empowerment in entrepreneurship and their suitability for collective contexts

The relationship between empowerment and entrepreneurship in collective societies is, in our view, insufficiently examined. Accepted definitions of empowerment and the assumptions underlying programs and research designs based on them result in outcomes that self-fulfil and, as a result, disappoint. Several issues are prevalent: the empowerment potential of programs is overestimated and the dominant view of what constitutes an ‘empowered self’ does not go deep enough to explore, and reframe, the self and its relationship to agency—two issues at the core of empowerment definitions and formulations. In this conceptual article, we examine the entrepreneurship and empowerment literature to suggest ways forward for the future health and relevance of the subject area. We highlight a serious methodological and perceptual issue within the literature, which offers many opportunities for theory development in the field