Recurrence quantification analysis of spatio-temporal chaotic transient in a closed unstirred Belousov-Zhabotinsky reaction

We analyse the transient spatio-temporal chaos that we observe in the Belousov-Zhabotinsky reaction performed in a closed unstirred batch reactor by recurrence quantification analysis (RQA). We characterize the chaotic transient by measuring the Lyapunov exponent and the Kaplan-Yorke dimension. The latter shows the fractality of the attractor. The importance of the coupling between hydrodynamics and kinetics for the onset of chaos is also shown

Femtosecond phase-resolved microscopy of plasmon dynamics in individual gold nanospheres

The selective optical detection of individual metallic nanoparticles (NPs) with high spatial and temporal resolution is a challenging endeavour, yet is key to the understanding of their optical response and their exploitation in applications from miniaturised optoelectronics and sensors to medical diagnostics and therapeutics. However, only few reports on ultrafast pump-probe spectroscopy on single small metallic NPs are available to date. Here, we demonstrate a novel phase-sensitive four-wave mixing (FWM) microscopy in heterodyne detection to resolve for the first time the ultrafast changes of real and imaginary part of the dielectric function of single small (<40nm) spherical gold NPs. The results are quantitatively described via the transient electron temperature and density in gold considering both intraband and interband transitions at the surface plasmon resonance. This novel microscopy technique enables background-free detection of the complex susceptibility change even in highly scattering environments and can be readily applied to any metal nanostructure

Structural and dipolar fluctuations in liquid water: a Car–Parrinello molecular dynamics study

A Car–Parrinello molecular dynamics simulation was performed to investigate the local tetrahedral order, molecular dipole fluctuations and their interrelation with hydrogen bonding in liquid water. Water molecules were classified in three types, exhibiting low, intermediate and high tetrahedral order. Transitions from low to high tetrahedrally ordered structures take place only through transitions to the intermediate state. The molecular dipole moments depend strongly on the tetrahedral order and hydrogen bonding. The average dipole moment of water molecules with a strong tetrahedral order around them comes in excellent agreement with previous estimations of the dipole moment of ice Ih molecules.Postprint (author's final draft

Digital processing of compressed image data

Certain image processing functions can be implemented more efficiently when the input data is in compressed form. Such an experimental system has been studied and simulated. The system consists of a one-dimensional Differential Pulse Code Modulation (DPCM) compressor, a one-dimensional non-recursive linear filter, and a one-dimensional DPCM decompressor, applied in that order. The implementation is more efficient because the filter is applied to the data in their compressed form, where fewer bits per pixel are required to represent them. A second, more conventional, system that contains the same functional elements but reverses the order of the filtration and decompression operations has also been implemented for comparison to the experimental one. The differences (errors) between the signals output from the two systems have been modeled and the models validated through experiments. It has been found that the systems can be made to yield equivalent results if certain parameters are constrained. These constraints do not put undue demands on system design nor do they substantially degrade system performance. Images produced by the two systems are presented and suggestions for additional work are discussed

The impact of integrating entrepreneurship education in a real estate degree programme on entrepreneurship intent

Thesis is submitted in partial fulfilment for the degree of M.Sc. (Building) in Property Development to the Faculty of Engineering and the Built Environment, School of Architecture and Planning at the University of the Witwatersrand, Johannesburg, 2017The lack of entrepreneurship is an obstacle to economic development. In South Africa (SA), disciplines are taught in a context that is enterprise-based, with no emphasis on the need to impart business start-up skills within specific disciplines. A culture of entrepreneurship is lacking, resulting in low records of entrepreneurship incidents in SA. The challenges and/or benefits of integrating entrepreneurship education within the South African real estate (RE) course and its effects on graduates’ entrepreneurial intent, is not well understood. The purpose of the research is to investigate whether the introduction of entrepreneurship education within the RE discipline would encourage graduates to become entrepreneurial in the practice of real estates. A mixed methodology approach has been used in this research. Primary and secondary research data has been made available in the form of questionnaire surveys of graduates and course directors/lecturers from the University of the Witwatersrand and other international universities that have entrepreneurship education embedded within their real estate programmes, as will be selected by the researcher. The research has found that both pedagogical strategies of course work and applying experiential learning teaching methods would be required to effectively integrate entrepreneurship education within a real estate programme in a manner that would stimulate graduates to be entrepreneurial in the practice of real estate, although it was not known whether the graduates would actually start businesses and when they intended to do so. It was also found that those students whose studies took place in real estate programmes that had entrepreneurship education embedded in them were more commercially aware. The integration of entrepreneurship education also resulted in an improvement of graduate self-esteem and confidence. Graduates were endowed with adequate professional, interpersonal, technical and business skills. The research, however, found the majority of real estate courses lacked in teaching graduates to be more versatile. The courses largely lacked in the provision of industry exposure and were inadequate in teaching graduates how to market themselves and their real estate businesses. According to the findings on the individual entrepreneurship test, graduates that studied entrepreneurship-based real estate courses had a higher probability of starting a business.MT201

Presupposition, assertion and the encoding of evidentiality in political discourse

The way linguistic messages are “packaged” in political discourse often reflects evidentially-based criteria and, notably, the intention of the politician to make his epistemic commitment more or less manifest in relation to the type of content proffered to the receiver. The present paper analyzes the evidential function of presupposition and assertion (apud Masia 2017) in a corpus of English, French and Italian political speeches, with the aim of highlighting how these units of information structure are strategically resorted to by politicians to modulate their commitment to more or less challengeable types of content. Data show that more challengeable content types (i.&nbsp;e. attacks and self-praises) are likely to be encoded as presupposition, which reduces the speaker’s commitment to their truth; in contrast, less challengeable content types (i.&nbsp;e. neutral/informative and stance-taking) are more likely to be asserted, with the speaker showing stronger commitment to their truth

<i>Ab initio</i> based polarizable force field parametrization

Experimental and simulation studies of anion-water systems have pointed out the importance of molecular polarization for many phenomena ranging from hydrogen-bond dynamics to water interfaces structure. The study of such systems at molecular level is usually made with classical molecular dynamics simulations. Structural and dynamical features are deeply influenced by molecular and ionic polarizability, which parametrization in classical force field has been an object of long-standing efforts. Although when classical models are compared to ab initio calculations at condensed phase, it is found that the water dipole moments are underestimated by ~30%, while the anion shows an overpolarization at short distances. A model for chloride-water polarizable interaction is parametrized here, making use of Car-Parrinello simulations at condensed phase. The results hint to an innovative approach in polarizable force fields development, based on ab initio simulations, which do not suffer for the mentioned drawbacks. The method is general and can be applied to the modeling of different systems ranging from biomolecular to solid state simulations

Manipulative impact of implicit communication: A comparative analysis of French, Italian and German political speeches

This paper presents the application of a quantitative model for measuring the impact of manipulative implicit linguistic strategies on a small comparable corpus of Italian, German and French political discourses. The aim is to show the cross-linguistic applicability of the model, originally developed and put to test on Italian. Furthermore, the analysis allows a quantitative and qualitative comparison of the three comparable corpora: some statistical correlations and tendencies in the frequency and type of linguistic implicit strategies are presented and put in relation not only with the language, but also with the political orientation of the speaker and with other parameters (context, subject, rhetorical style). Results show that the model can be applied to multiple languages and that inter- and intra-linguistic tendencies in the use of manipulative implicit linguistic strategies can be appreciated