The economics of addiction: an experimental investigation

Addiction is an ideal puzzle for economic theory: why do most addicts expend resources to acquire their targets of addiction but then incur real costs to try and reduce or limit their consumption of these goods? Furthermore, why is the typical course of addiction characterised by repeated unsuccessful attempts to quit prior to final abstention? From the standpoint of standard consumer theory in economics these patterns of behaviour are difficult to rationalise. There is a rich theoretical literature in economics which models habit-forming behaviours, of which addiction is the exemplar, but there is a paucity of experimental economic studies eliciting and comparing the preferences – specifically, risk and time preferences – that economic theory suggests may differ between addicts and non-addicts. The experimental research that has been conducted has been dominated by psychologists, and some economists have begun to follow their methodological lead. However, detailed reviews of the experimental literature on addiction highlight a number of methodological and statistical flaws in the ways these data have been collected and analysed. This thesis is primarily concerned with methodological and statistical issues at the boundary between economics and psychology as these bear upon developing a general, consistent explanation of addiction. An incentive-compatible experimental design is formulated which lends itself to the estimation of several different theories of choice under risk and over time. In addition, a full information maximum likelihood statistical framework, which is consistent with the data generating processes proposed by structural theories and accounts for subject errors in decision making, is used to explore the relationship between risk preferences, time preferences and addiction. This thesis challenges some of the maintained assumptions in the addiction literature; e.g., that the probability discounting and hyperbolic discounting models best characterise choice under risk and over time, respectively. But it also replicates a previous finding; i.e., that smokers tend to discount the future more heavily than non-smokers. It shows, therefore, that some results withstand careful methodological and statistical scrutiny, whereas other results do not. Ultimately, this thesis argues that tools from experimental economics and econometrics, which have been under-used in addiction studies, contribute to a more accurate and reliable characterisation of this phenomenon

Methods for determination of coastal development setback lines in South Africa.

Thesis (DEng)--Stellenbosch University, 2016.ENGLISH ABSTRACT: Implementation of the ICM Act (2008) has made it a legal requirement to determine coastal setback lines in all the coastal provinces of South Africa. Coastal development setback lines (or “coastal management lines”) need to make provisions for physical coastal/marine processes, as well as “softer” more subjective issues and considerations, e.g. environmental, public access, heritage, sense of place, aesthetics, etc. Both the literature review and recent setback line workshops held in South Africa have highlighted the lack of consistent methods to determine setback lines, as well as the major confusion around how to proceed. The literature review found that the primary coastal processes components of setback lines were related to coastal flooding levels and coastal erosion. Both of these, including sub-components, were not satisfactorily dealt with in terms of methods applied to date. To alleviate these problems, appropriate setback line methods are sought for “data poor” environments, that can be efficiently applied in large study areas, but that are still sufficiently robust and defendable. In view of South Africa’s generally very exposed coastline (and the possibility of progressive climate change impacts), the escalating South African coastal development, and the above mentioned problems, the need for appropriate, practical and implementable methodologies to determine setback lines is clear. This thesis describes the author’s research concerning methods for the determination of coastal development setback lines in South Africa, and focuses strongly on the abiotic (geophysical) components of setback lines. Geophysical coastal hazards and spatial vulnerability, and their relevance to setback lines are considered. A practical coastal hazard and vulnerability evaluation technique, applied to European coastal conditions but applicable to South African conditions including poor data availability, was adapted and further developed (building on methods proposed by Theron et al, 2010a, 2012), to include additional forcing factors considered to be relevant under South African conditions. Following an extensive literature review and testing of several different wave runup models against local data, it is concluded that the models of Nielsen and Hanslow (1991) and Mather et al (2011) are the best of the available models and are adequate for application in South Africa, but should be used with certain adaptations as recommended herein. New methods were developed and two alternative approaches are proposed to predict short-term shoreline erosion, requiring less input data, and that are also suitable for larger scale approaches (rather than being limited by the constraints of conventional methods). Current methods of determining setback lines have not adequately taken dune effects into account. Thus a novel approach is proposed for quantifying dune effects on normal shoreline erosion estimates. Other important components of and requirements for setback lines are dealt with. Thus discussions and specific recommendations, suggestions and guidance are provided on another eight components/aspects necessary for determining setback lines. Finally, all the necessary setback line methodologies and aspects are put together, explaining how they should be applied. The basic components are catalogued and a compilation of the steps required to determine coastal development setback lines is provided. Recommended procedures and methods for conducting/completing each of the steps are given.AFRIKAANSE OPSOMMING: Die implementering van die Geïntegreerde Kusbestuurs-wetgewing van 2008 het dit ‘n wetlike vereiste gemaak om kus-ontwikkelings-terugsetlyne te bepaal in al die kusprovinsies van Suid-Afrika. Kus-ontwikkelings-terugsetlyne (ook bekend as kus-bestuurslyne) moet voorsiening maak vir fisiese kus/mariene prosesse, asook “sagter” meer subjektiewe aspekte en oorwegings, byvoorbeeld omgewingsimpakte, publieke toegang, erfenis, estetika/besienswaardigheid, gewaarwording van skoonheid/”plek-sin” (‘sense of place”), ens. ‘n Literatuur oorsig sowel as onlangse werkswinkels wat in Suid-Afrika gehou is oor terugsetlyne, het beklemtoon dat daar ‘n gebrek is aan konsekwente metodes/tegnieke om terugsetlyne te bepaal, asook dat daar grootskaalse verwarring heers oor hoe om met die bepaling daarvan voort te gaan. Die literatuur oorsig het bevind dat die primêre kusproses-komponente van terugsetlyne verband hou met vloedhoogtes langs die kus sowel as kuserosie. Beide hierdie komponente asook sub-komponente, was onbevredigend hanteer in die metodes wat tot dusver toegepas is. Om hierdie probleme te oorkom, word toepaslike terugsetlyn metodes benodig, wat geskik is vir beperkte data beskikbaarheid. Dié metodes moet ook effektief toegepas kan word in groot studie-areas, maar moet steeds betroubaar en onaanvegbaar wees. Dit is duidelik dat in die lig van Suid-Afrika se algemeen baie blootgestelde kuslyn (en die moontlikheid van ergerwordende klimaatsveranderings-impakte), die snelgroeiende Suid-Afrikaanse kusontwikkeling, en bogenoemde ander probleme, daar die behoefte bestaan vir toepaslike, praktiese en implementeerbare metodes om terugsetlyne te bepaal. Hierdie tesis beskryf die outeur se navorsing oor metodes om kus-ontwikkelings-terugsetlyne in Suid-Afrika te bepaal, en is sterk gefokus op die abiotiese (geofisiese) komponente/aspekte van terugsetlyne. Geofisiese kus-gevare en ruimtelike kwesbaarheid, en hul belang vir/op terugsetlyne word oorweeg. ‘n Praktiese kus-gevaar en kwesbaarheid evaluerings-tegniek, voorheen toegepas op Europese kus-toestande, maar toepaslik vir Suid-Afrikaanse toestande en data beskikbaarheid, is aangepas en verder ontwikkel (gebaseer op metodes voorgestel deur Theron et al, 2010a, 2012), om bykomende faktore in te sluit wat toepaslik is vir Suid-Afrikaanse toestande. Na ‘n uitgebreide literatuur oorsig en die toets van verskeie golf-oploop modelle teen plaaslike data, is bevind dat die modelle van Nielsen en Hanslow (1991) en Mather et al (2011) die bestes is van die beskikbare modelle en dat hul voldoende is vir toepassing in Suid-Afrika, maar dat hul gebruik behoort te word met sekere aanpassings soos in hierdie tesis aanbeveel word. Nuwe metodes is ontwikkel en twee alternatiewe benaderings word voorgestel om korttermyn kus-erosie te voorspel, wat minder invoer data benodig, en wat ook geskik is vir toepassings op groter skaal (eerder as om beperk te word deur die tekortkominge van gebruiklike metodes). Huidige metodes om terugsetlyne te bepaal het nie duin-effekte voldoende in ag geneem nie. Daar word dus ‘n nuwe benadering voorgestel om duin-effekte op normale kusereosie beramings te kwantifiseer. Ander belangrike komponente van, en benodigdhede vir terugsetlyne word ook behandel. Besprekings en spesifieke aanbevelings, voorstelle en riglyne word voorsien wat handel oor ‘n verdere agt komponente/aspekte wat benodig word vir die bepaling van terugsetlyne. Ten slotte word al die benodigde terugsetlyn-medodes en aspekte bymekaar gebring, en word daar verduidelik hoe hul toegepas behoort te word. Al die basiese komponente word gelys en ‘n samestelling van die stappe wat benodig word om kus-ontwikkelings-terugsetlyne te bepaal, word gegee. Aanbevole prosedures en metodes word gegee om elk van die stappe uit te voer en te voltooi

Kiri Wilhelm Reichelile

Andre, Christian Karl, 1763-1831, saksa kirjanik ja pedagoogReichel, Wilhelm, 1783-pärast 1836, Cotta trüki- ja kirjastusfirma faktor ja korrektor AugsburgisSoovitused ühe käsikirja trükkiviimisel, ootab kiirpostiga Wienist ja Frankfurdist artikli

On the Influence of Diurnal and Subdiurnal Signals in the Normal Vector on Large Ring Laser Gyroscope Observations

The ring laser gyroscope (RLG) technique has been investigated for over 20 years as a potential complement to space geodetic techniques in measuring Earth rotation. However, RLGs are also sensitive to changes in their terrestrial orientation. Therefore in this paper, we review how the high-frequency band (i.e. signals shorter than 0.5 cycle per day) of the known phenomena causing site deformation contribute to the RLG observable, the Sagnac frequency. We study the impact of solid Earth tides, ocean tidal loading and non-tidal loading phenomena (atmospheric pressure loading and continental hydrosphere loading). Also, we evaluate the differences between available models of the phenomena and the importance of the Love numbers used in modeling the impact of solid Earth tides. Finally, we compare modeled variations in the instrument orientation with the ones observed with a tiltmeter. Our results prove that at the present accuracy of the RLG technique, solid Earth tides and ocean tidal loading effects have significant effect on RLG measurements, and continental hydrosphere loading can be actually neglected. Regarding the atmospheric loading model, its application might introduce some undesired signals. We also show that discrepancies arising from the use of different models can be neglected, and there is almost no impact arising from the use of different Love numbers. Finally, we discuss differences between data reduced with tiltmeter observations and these reduced with modeled signal, and potential causes of this discrepancies

On the Predictive Power of Objective Intelligibility Metrics for the Subjective Performance of Deep Complex Convolutional Recurrent Speech Enhancement Networks

Speech enhancement (SE) systems aim to improve the quality and intelligibility of degraded speech signals obtained from far-field microphones. Subjective evaluation of the intelligibility performance of these SE systems is uncommon. Instead, objective intelligibility measures (OIMs) are generally used to predict subjective performance increases. Many recent deep learning (DL) based SE systems, are expected to improve the intelligibility of degraded speech as measured by OIMs. However, validation of the ability of these OIMs to predict subjective intelligibility when enhancing a speech signal using DL-based systems is lacking. Therefore, in this study, we evaluate the predictive performance of five popular OIMs. We compare the metrics' predictions with subjective results. For this purpose, we recruited 50 human listeners, and subjectively tested both single channel and multi-channel Deep Complex Convolutional Recurrent Network (DCCRN) based speech enhancement systems. We found that none of the OIMs gave reliable predictions, and that all OIMs overestimated the intelligibility of ‘enhanced’ speech signals.acceptedVersio