Statistical hyperbolicity of relatively hyperbolic groups

We prove that a non-elementary relatively hyperbolic group is statistically hyperbolic with respect to every finite generating set. We also establish statistical hyperbolicity for certain direct products of two groups, one of which is relatively hyperbolic.Comment: 12 pages; Several corrections and improvements on the exposition after referee report. Version to appear in Algebraic and Geometric Topolog

Statistical Hyperbolicity of Relatively Hyperbolic Groups

In this work, we begin by defining what it means for a group to be statistically hyperbolic. We then give several examples of groups, including non-elementary hyperbolic groups, which either are statistically hyperbolic or are not. Following that, we define what it means for a group to be relatively hyperbolic. Finally, in the main portion of this work, we show that groups which are relatively hyperbolic, with a few additional conditions in place, must also be statistically hyperbolic

Extending knowledge management beyond organisational borders – barriers for South African construction organisations

Previous research raised the question of why South African organisations do not extend their Knowledge Management (KM) practices beyond their organisational borders. Therefore, there is a need to examine the barriers faced by construction organisations when trying to extend KM activities beyond organisational borders towards encouraging the South African construction sector to improve upon its collective KM maturity. This research utilised a quantitative approach which initially examined the available literature on the topic of Knowledge Management and the barriers found inhibiting its implementation. From this knowledge a survey instrument was developed and circulated to 499 construction professionals based in South Africa to elicit their opinions on Knowledge Management, extending KM activities beyond organisational boundaries and the barriers potentially inhibiting these activities. A total of 93 usable data sets were received and subjected to statistical analysis. This research found that there was a clear positive opinion towards KM and to extending these activities beyond organisational borders. The perception that by extending KM activities beyond organisational borders may negatively impact the organisations competitiveness is still prevalent and is a barrier to extending KM activities beyond organisational borders. Further it was found that the lack of time allocated to KM activities was an inhibitor to KM activities bother internally and from extending these KM activities beyond organisational borders. However, the amount of training given on KM and support of management was only found to be of significant concern in the less mature organisations and therefore may inhibit KM activities but were not a clear inhibitor to extending these activities beyond organisational borders. Continuity in the makeup of project teams was identified as a potential route to improve project performance and the current contracts utilised in the sector did not appear to currently impact knowledge sharing. Encouragingly it was found that knowledge was not withheld by employees to improve job security and further the challenges faced by multiple languages being spoken in the project environment and in coordinating TMO's did not register as significant inhibitors to knowledge sharing. This research's findings show that professionals in the South African construction sector have a positive opinion towards KM and extending these activities beyond organisational borders. Barriers do exist in the sector that are inhibiting knowledge managements implementation and growth, however by highlighting these issues it is possible for organisations to overcome the challenges faced, grow their knowledge management maturity and extract the most out of the strategies implemented. Based on these findings, the study recommended that there is a need to establish partnerships and longstanding relationships which foster knowledge transfer to overcome the negative perception that extending knowledge management activities beyond organisational borders may negatively impact competitiveness. This research was limited by the response rate to the survey circulated being low with only 93 valid data sets in the sample for statistical analysis. Further most respondents to the survey were from small and micro organisations who had low KM maturities and therefore the results for this research cannot claim to represent the construction sector of South Africa as a whole

Anthropometric characteristics, upper-body strength, and sprint paddling performance in competitive surfers

The present study examined the potential differences in anthropometric characteristics, upper-body strength, and sprint paddling performance between youth and senior competitive surfers. Twenty competitive male surfers (19.1±6.8 years, 168.2±11.3 cm, 61.7±13.6 kg) were assessed for stature, mass, arm-span, ∑ 7 site skinfold thickness, Lean-Mass Ratio (LMR, ∑ 7 site skinfold/kg body-mass), pronated pull-up 1 repetition maximum (1 RM) and sprint paddling performance from a stationary start to 15 m. Independent t-tests were used to compare potential differences between youth (n:10) and senior group (n:10) of competitive surfers, with Cohen’s Effect Size (d) applied to reflect the magnitude of any differences observed. Senior surfers were not different from youth surfers for ∑ 7 site skinfold thickness, yet had greater stature (p\u3c0.001, d=2.7) and mass (p\u3c0.001, d=2.8). Consequently, the composite lean mass ratio (body-mass/∑ 7 site skinfold thickness, LMR) was greater (p=0.001, d=1.7) in senior competitive surfers. The senior surfers were faster in the 0-15 m sprint paddle test (p\u3c0.001, d=2.9), possessed higher peak paddling velocity (p\u3c0.001, d=2.3) and had greater absolute 1 RM pull-up strength (p\u3c0.001, d=2.8) and 1 RM pull-up strength relative to body-mass (1 RM pull-up mass/subjects body-mass) (p\u3c0.001, d=2.2). The results of this study suggest that practitioners working with competitive surfers should consider the importance of sprint paddle performance in surfers, and the need to optimize lean mass and relative strength, as these factors appear to distinguish between surfers of higher and lower athletic development and competitive level in the surfing population

The Design and Installation of a Combined Concentrating Power Station, Solar Cooling System and Domestic Hot Water System

AbstractThe University of Technology, Sydney (UTS) has built a unique tri-generation system that provides chilled water, hot water, and electricity to their new Faculty of Engineering and Information Technology (FEIT) building. It integrates parabolic trough collectors, flat plate collectors, photovoltaic panels, and wind power as generators with thermal and chemical energy storage. The heat from the parabolic trough collectors is used to run a small-scale Organic Rankine Cycle (ORC) unit as well as a small-scale ammonia/water absorption chiller to provide either electricity or chilled water, respectively. The condenser heat from both units is fed into the domestic hot water (DHW) supply of the building in addition to the solar heat from the flat plate and the parabolic trough collectors. The design concept including the main system components and the system control strategy are described in detail. Further, the lessons learned during the installation and commissioning of the complex tri-generation system are given. As a novelty in this area, the tri-generation system has been specifically designed to allow students and researchers to work with it, hence this paper also describes the wide range of teaching opportunities for undergraduate and graduate engineering students as well as post-doc researchers

Expansion of the ligand knowledge base for chelating P,P-donor ligands (LKB-PP)

[Image: see text] We have expanded the ligand knowledge base for bidentate P,P- and P,N-donor ligands (LKB-PP, Organometallics2008, 27, 1372–1383) by 208 ligands and introduced an additional steric descriptor (nHe(8)). This expanded knowledge base now captures information on 334 bidentate ligands and has been processed with principal component analysis (PCA) of the descriptors to produce a detailed map of bidentate ligand space, which better captures ligand variation and has been used for the analysis of ligand properties

Antiviral protection and the importance of Wolbachia density and: tissue tropism in Drosophila simulans

Wolbachia, a maternally transmitted endosymbiont of insects, is increasingly being seen as an effective biological control agent that can interfere with transmission of pathogens, including dengue virus. However, the mechanism of antiviral protection is not well understood. The density and distribution of Wolbachia in host tissues have been implicated as contributing factors by previous studies with both mosquitoes and flies. Drosophila flies infected with five diverse strains of Wolbachia were screened for the ability to mediate antiviral protection. The three protective Wolbachia strains were more closely related and occurred at a higher density within whole flies than the two nonprotective Wolbachia strains. In this study, to further investigate the relationship between whole-fly Wolbachia density and the ability to mediate antiviral protection, tetracycline was used to decrease the abundance of the high-density, protective Wolbachia strain wAu prior to viral challenge. Antiviral protection was lost when the density of the protective Wolbachia strain was decreased to an abundance similar to that of nonprotective Wolbachia strains. We determined the Wolbachia density and distribution in tissues of the same five fly-Wolbachia combinations as used previously. The Wolbachia density within the head, gut, and Malpighian tubules correlated with the ability to mediate antiviral protection. These findings may facilitate the development of Wolbachia biological control strategies and help to predict host-Wolbachia pairings that may interfere with virus-induced pathology

Pan-chromatic observations of the remarkable nova LMC 2012

We present the results of an intensive multiwavelength campaign on nova LMC 2012. This nova evolved very rapidly in all observed wavelengths. The time to fall two magnitudes in the V band was only 2 days. In X-rays the super soft phase began 13$\pm$5 days after discovery and ended around day 50 after discovery. During the super soft phase, the \Swift/XRT and \Chandra\ spectra were consistent with the underlying white dwarf being very hot, $\sim$ 1 MK, and luminous, $\sim$ 10$^{38}$ erg s$^{-1}$. The UV, optical, and near-IR photometry showed a periodic variation after the initial and rapid fading had ended. Timing analysis revealed a consistent 19.24$\pm$0.03 hr period in all UV, optical, and near-IR bands with amplitudes of $\sim$ 0.3 magnitudes which we associate with the orbital period of the central binary. No periods were detected in the corresponding X-ray data sets. A moderately high inclination system, $i$ = 60$\pm$10^{\arcdeg}, was inferred from the early optical emission lines. The {\it HST}/STIS UV spectra were highly unusual with only the \ion{N}{5} (1240\AA) line present and superposed on a blue continuum. The lack of emission lines and the observed UV and optical continua from four epochs can be fit with a low mass ejection event, $\sim$ 10$^{-6}$ M$_{\odot}$, from a hot and massive white dwarf near the Chandrasekhar limit. The white dwarf, in turn, significantly illuminated its subgiant companion which provided the bulk of the observed UV/optical continuum emission at the later dates. The inferred extreme white dwarf characteristics and low mass ejection event favor nova LMC 2012 being a recurrent nova of the U Sco subclass.Comment: 18 figures, 6 tables (one online only containing all the photometry