ASSISTED DEVELOPMENT OF MESOPHASE PITCH WITH DISPERSED GRAPHENE AND ITS RESULTING CARBON FIBERS

The efficacy of dispersed reduced graphene oxide (rGO) as a nucleation site for the growth of mesophase in an isotropic pitch was investigated and quantified in this study. Concentrations of rGO were systematically tested in an isotropic petroleum and coal-tar pitch during thermal treatments and compared to pitch without rGO. The mesophase content of each thermally treated pitch was quantified by polarized light point counting. Further characterization of softening temperature and insolubles were quantified. Additionally, the pitches with and without rGO were melt spun, graphitized, and tensile tested to determine the effects of rGO on graphitized fiber mechanical properties and fiber morphology

Students’ perceptions on the effectiveness of product placements: a case study of a private higher education institution in Durban.

Masters Degree. University of KwaZulu-Natal, Durban.The development of technology has changed the way in which business is practiced and has had a profound impact on marketing and advertising. Organisations and brands have identified that it is important to attract and retain loyal customers. Advertising and the implementation of marketing communications strategies has been designed to create awareness about a product or brand and change the purchasing behaviour of consumers The saturation of advertisements within the various media has propelled marketers to employ not only a variety of approaches but to seek unique ways in which to market their products. The introduction of television has opened the door for companies to strategically place their products in movies, television programmes and music videos. The youth market represents an attractive market for many organisations, as satisfying this demographic’s needs early in their life cycle can result in the development of long-lasting and profitable relationships. As the youth are highly exposed to movies and television programmes, many marketers have been attracted to add product placements in visual media into their overall marketing communications strategy. However, results have indicated that product placements are similar to traditional advertising in terms of capturing the audience’s attention, developing positive feelings towards the product and recall when faced with a purchase decision. It was also established that students believe other marketing communication tools, such as digital and social media advertising, sponsorships, sales promotions and even traditional advertising as being more effective than product placements. This finding allows marketers to question whether they should use this approach when targeting a younger demographic, such as students

Physics validation studies for muon collider detector background simulations

Within the broad discipline of physics, the study of the fundamental forces of nature and the most basic constituents of the universe belongs to the field of particle physics. While frequently referred to as 'high-energy physics,' or by the acronym 'HEP,' particle physics is not driven just by the quest for ever-greater energies in particle accelerators. Rather, particle physics is seen as having three distinct areas of focus: the cosmic, intensity, and energy frontiers. These three frontiers all provide different, but complementary, views of the basic building blocks of the universe. Currently, the energy frontier is the realm of hadron colliders like the Tevatron at Fermi National Accelerator Laboratory (Fermilab) or the Large Hadron Collider (LHC) at CERN. While the LHC is expected to be adequate for explorations up to 14 TeV for the next decade, the long development lead time for modern colliders necessitates research and development efforts in the present for the next generation of colliders. This paper focuses on one such next-generation machine: a muon collider. Specifically, this paper focuses on Monte Carlo simulations of beam-induced backgrounds vis-a-vis detector region contamination. Initial validation studies of a few muon collider physics background processes using G4beamline have been undertaken and results presented. While these investigations have revealed a number of hurdles to getting G4beamline up to the level of more established simulation suites, such as MARS, the close communication between us, as users, and the G4beamline developer, Tom Roberts, has allowed for rapid implementation of user-desired features. The main example of user-desired feature implementation, as it applies to this project, is Bethe-Heitler muon production. Regarding the neutron interaction issues, we continue to study the specifics of how GEANT4 implements nuclear interactions. The GEANT4 collaboration has been contacted regarding the minor discrepancies in the neutron interaction cross sections for boron. While corrections to the data files themselves are simple to implement and distribute, it is quite possible, however, that coding changes may be required in G4beamline or even in GEANT4 to fully correct nuclear interactions. Regardless, these studies are ongoing and future results will be reflected in updated releases of G4beamline

Ecology, Evolution, and Sexual Selection in the Invasive, Globally Distributed Small Indian Mongoose (\u3ci\u3eUrva auropunctata\u3c/i\u3e)

Introduced species provide rare opportunities to test evolutionary hypotheses in situ by creating so-called natural experiments. Natural experiments are situations in nature that resemble laboratory studies by allowing for comparisons of a “control” group (i.e., a species’ native range) with “experimental” groups (i.e., a species’ introduced range). In particular, introduced animals allow us to investigate evolutionary dynamics in complex, long-lived organisms in ways that would otherwise be impossible in a laboratory setting. One such introduced animal is the small Indian mongoose (Urva auropunctata, formerly Herpestes auropunctatus). Native to South Asia, the small Indian mongoose’s introduction to more than 70 mostly tropical island locations worldwide represents an excellent natural experiment: the dates of introduction and numbers introduced are well documented, most locations of introduction are reproductively isolated from each other and thus provide numerous experimental replicates, and most introduced populations have been reproducing for at least 200 generations. In its introduced range, the small Indian mongoose is released from interspecific competition and predation, and as a result, it has become densely populated and highly invasive. In fact, the IUCN named it one of the 100 worst invasive species on the planet. Consequently, the vast majority of the literature on this species is devoted to understanding its ecological impacts on local biodiversity. In contrast, however, relatively little is known of its ecology and natural history in its native range where, in some regions, it is protected. Lacking entirely, for instance, are data pertaining to the operation of sexual selection and its mate choice behavior. Finally, while four studies have investigated evolutionary changes that small Indian mongooses have undergone since introduction, only one has investigated adaptive changes, and this study mistakenly included individuals of a separate species in its analysis, leaving its results and conclusions uninterpretable. In this dissertation, I present an exhaustive review of the available literature on the small Indian mongoose (Chapter 1), report on the first quantitative natural history data ever collected in its native range (Chapter 2), identify, for the first time in this species, features under sexual selection (Chapter 3), and, taking advantage of its natural experiment, demonstrate the rapid adaptive evolution of two of its sexually selected traits (Chapter 4). In Chapter 1, I review literature on all ecologically relevant information of the small Indian mongoose including, their taxonomy; native and introduced ranges, and history of introduction; basic biology; impacts as an invasive species, including their status as a failed biological control, the local species they have impacted, the various management efforts around the globe, and their role in disease transmission; and finally, their use as an evolutionary model system. In Chapter 2, I collect basic morphological measurements of small Indian mongooses from several populations in their native range in northern India. I also radio-collared and tracked 17 individuals for several months, and estimate that home ranges sizes in the native range are comparable to, though generally smaller than, estimates in the introduced range. I also find that small Indian mongooses prefer areas of human habitation and avoid forested and open areas. In Chapter 3, I report on an investigation of the small Indian mongoose on the island of Hawaii. I conclude that the anal pad, their scent-marking tool, is a sexually selected trait in males, as indicated by its high male-biased sexual size dimorphism, and its condition-dependence and positive relationship with body size in males, but not females. From these results, I infer that males likely use scent as a sexual signal. Finally, in Chapter 4, in an effort to understand how sexually selected traits change after becoming established, I collect similar morphological data to those collected in Chapter 2 and Chapter 3 from three additional areas of introduction, Jamaica, St. Croix, and Mauritius. I then compare these data together with those collected from the island of Hawaii, to data from the native range in India. I find that male, but not female, anal pads decreased in size according to time since introduction, and its relation to body size and condition weakened. In addition, I find that testis size increased after introduction. My results suggest an inversion in the relative contributions to fitness of two sexually selected traits in males, demonstrated by the rapid evolution of these features after introduction. Thus, I conclude that, relative to the native range, the increased encounter rates on islands of introduction (due to the markedly denser populations) have relaxed sexual selection on scent marking in males, but intensified sperm competition. My findings demonstrate that the fitness of sexually selected traits, like any other traits under natural selection, is determined by environment in which the traits are expressed

Visualizing Spacetime Curvature via Frame-Drag Vortexes and Tidal Tendexes II. Stationary Black Holes

When one splits spacetime into space plus time, the Weyl curvature tensor (which equals the Riemann tensor in vacuum) splits into two spatial, symmetric, traceless tensors: the tidal field $E$, which produces tidal forces, and the frame-drag field $B$, which produces differential frame dragging. In recent papers, we and colleagues have introduced ways to visualize these two fields: tidal tendex lines (integral curves of the three eigenvector fields of $E$) and their tendicities (eigenvalues of these eigenvector fields); and the corresponding entities for the frame-drag field: frame-drag vortex lines and their vorticities. These entities fully characterize the vacuum Riemann tensor. In this paper, we compute and depict the tendex and vortex lines, and their tendicities and vorticities, outside the horizons of stationary (Schwarzschild and Kerr) black holes; and we introduce and depict the black holes' horizon tendicity and vorticity (the normal-normal components of $E$ and $B$ on the horizon). For Schwarzschild and Kerr black holes, the horizon tendicity is proportional to the horizon's intrinsic scalar curvature, and the horizon vorticity is proportional to an extrinsic scalar curvature. We show that, for horizon-penetrating time slices, all these entities ($E$, $B$, the tendex lines and vortex lines, the lines' tendicities and vorticities, and the horizon tendicities and vorticities) are affected only weakly by changes of slicing and changes of spatial coordinates, within those slicing and coordinate choices that are commonly used for black holes. [Abstract is abbreviated.]Comment: 19 pages, 7 figures, v2: Changed to reflect published version (changes made to color scales in Figs 5, 6, and 7 for consistent conventions). v3: Fixed Ref

Frame-Dragging Vortexes and Tidal Tendexes Attached to Colliding Black Holes: Visualizing the Curvature of Spacetime

When one splits spacetime into space plus time, the spacetime curvature (Weyl tensor) gets split into an "electric" part E_{jk} that describes tidal gravity and a "magnetic" part B_{jk} that describes differential dragging of inertial frames. We introduce tools for visualizing B_{jk} (frame-drag vortex lines, their vorticity, and vortexes) and E_{jk} (tidal tendex lines, their tendicity, and tendexes), and also visualizations of a black-hole horizon's (scalar) vorticity and tendicity. We use these tools to elucidate the nonlinear dynamics of curved spacetime in merging black-hole binaries.Comment: 4 pages, 5 figure

Visualizing Spacetime Curvature via Frame-Drag Vortexes and Tidal Tendexes III. Quasinormal Pulsations of Schwarzschild and Kerr Black Holes

In recent papers, we and colleagues have introduced a way to visualize the full vacuum Riemann curvature tensor using frame-drag vortex lines and their vorticities, and tidal tendex lines and their tendicities. We have also introduced the concepts of horizon vortexes and tendexes and 3-D vortexes and tendexes (regions where vorticities or tendicities are large). Using these concepts, we discover a number of previously unknown features of quasinormal modes of Schwarzschild and Kerr black holes. These modes can be classified by mode indexes (n,l,m), and parity, which can be electric [(-1)^l] or magnetic [(-1)^(l+1)]. Among our discoveries are these: (i) There is a near duality between modes of the same (n,l,m): a duality in which the tendex and vortex structures of electric-parity modes are interchanged with the vortex and tendex structures (respectively) of magnetic-parity modes. (ii) This near duality is perfect for the modes' complex eigenfrequencies (which are well known to be identical) and perfect on the horizon; it is slightly broken in the equatorial plane of a non-spinning hole, and the breaking becomes greater out of the equatorial plane, and greater as the hole is spun up; but even out of the plane for fast-spinning holes, the duality is surprisingly good. (iii) Electric-parity modes can be regarded as generated by 3-D tendexes that stick radially out of the horizon. As these "longitudinal," near-zone tendexes rotate or oscillate, they generate longitudinal-transverse near-zone vortexes and tendexes, and outgoing and ingoing gravitational waves. The ingoing waves act back on the longitudinal tendexes, driving them to slide off the horizon, which results in decay of the mode's strength. (iv) By duality, magnetic-parity modes are driven in this same manner by longitudinal, near-zone vortexes that stick out of the horizon. [Abstract abridged.]Comment: 53 pages with an overview of major results in the first 11 pages, 26 figures. v2: Very minor changes to reflect published version. v3: Fixed Ref