The finite sample properties of three semiparametric estimators, several versions of the modified rescaled range, MMR, and three versions of the GHURST estimator are investigated. Their power and size for testing for long memory under short-run effects, joint short and long-run effects, heteroscedasticity and t-distributions are given using Monte Carlo methods. The MMR with the Barlett window is generally robust with the disadvantage of a relatively small power. The trimmed Whittle likelihood has high power in general and is robust expect for large short-run effects. The tests are applied to chandes in exchange rate series (daily data) of 6 major countries. The hypothesis of no fractional integration is rejected for none of the series. (author's abstract) / Series: Preprint Series / Department of Applied Statistics and Data Processing

Yes / The stereochemical outcome of the epoxidation of Δ14–15 cholestanes with mCPBA is controlled by the steric bulk of a C17 substituent. When the C17 is in the β configuration, the epoxide is formed in the α face, whereas if the C17 is trigonal (flat) or the substituent is in the α configuration, the epoxide is formed in the β face. The presence of a hydroxyl substituent at C20 does not influence the stereochemical outcome of the epoxidation. / We thank University of Bradford for a bursary (MA).

Economic theory does not always specify the functional relationship between dependent and explanatory variables, or even isolate a particular set of covariates. This means that model uncertainty is pervasive in empirical economics. In this paper, we indicate how Bayesian semi-parametric regression methods in combination with stochastic search variable selection can be used to address two model uncertainties simultaneously: (i) the uncertainty with respect to the variables which should be included in the model and (ii) the uncertainty with respect to the functional form of their effects. The presented approach enables the simultaneous identification of robust linear and nonlinear effects. The additional insights gained are illustrated on applications in empirical economics, namely willingness to pay for housing, and cross-country growth regression.

Syftet med uppsatsen är att studera vegetationsutvecklingen och dess förändringar i Finja med hjälp av pollenanalys. De frågor jag önskade få svar på var om det fanns några spår av en vikingatida storgård i Finja, samt eventuella spår av betydande djuruppfödning i området. Finja är rik på fornlämningar från brons-, järnålder och meddeltid, som bekräftar min tes om att Finja/ Mölleröd haft en betydande roll i området runt Finja sjön, troligtvis med odling och handel längs Almaån. En paleoekologisk analys genomfördes från en lagerföljd från Vånga mosse, Finja. Totalt togs fyra meter torvprov upp ur mossen. I den översta metern plockades fjorton prover ut till analys. Två 14C dateringar visade vilket tidsspann proven befann sig i. Cirka 600 pollen räknades från varje prov som sedan sammanställdes i olika pollendiagram som visar förändringarna i vegetationen mellan 660 e.Kr. – 1587 e.Kr. Vånga mosse visar på kontinuerlig markanvändning under hela den undersökta perioden. Stora förändringar kan ses i pollenkurvorna för odlingsindikatorerna från provets början som ökar till höga värden vid mitten av 700 talet e.Kr. med Secale (råg) som största indikator.  Förändringen visar att området haft en betydande odlingsverksamhet i cirka 150 år under vikingatiden, vilket styrker tesen om en storgårdsetablering i Finja under denna period. Efter odlingsuppgången minskar aktiviteterna i området, dock med fortsatt kontinuitet i både odling- och betesmarker. Området runt Vånga mosse genomgår en kraftig röjning från tidigt 1000 tal e.Kr. till cirka 1200 e.Kr., tillsammans med en expansiv nyodlingsperiod från 1000 e.Kr., som kan ses i båda sädesarterna i diagrammen. Detta resultat tillsammans med andra historiska indikatorer visar på en permanent etablering i Finja vid slutet av 900 e.Kr. Under de nästkommande århundrandena kan ytterligare två nyodlingstoppar ses, en vid mitten av 1000 talet e.Kr. som eventuellt kan kopplas samman med upprättandet av kyrkan, och en vid början av 1200 talet e.Kr.

The reporting of the financial results of an organisation is the responsibility of the management of that organisation. However, value may be added to the financial statements by the auditing of such financial statements and by the opinion expressed by the external auditors. Furthermore, there is the expectation on the part of the users of the financial statements that the auditors are also responsible for detecting fraud and, more specifically, financial statement fraud. It was stated in the Association of Certified Fraud Examiners 2010 Report to the Nations that it is the high-level perpetrators who cause the greatest damage to their organisations. The costs arising from financial statement fraud were found to be more than three times higher than the costs arising from fraud committed by lower-level managers and nine times more than the costs involved in employee fraud. The question, thus, arises as to why the auditors would not detect financial statement fraud timeously. The external audit profession has formulated a specific standard which addresses the responsibility of the external auditor as regards the detection of fraud during the audit of financial statements. The aim of this research was to determine the adequacy of the internal auditor standards as regards providing guidance to the internal auditors in terms of detecting financial statement fraud. This research highlighted the lack of guidance in the internal audit standards regarding the responsibility of internal auditors relating to financial statement fraud. In the main, both the directives and the guidance refer to fraud in general but not specifically to financial statement fraud and, thus, the professional internal auditor is forced to seek guidance outside of the internal audit standards as regards the detection of financial statement fraud. / MPhil University of Pretoria, 2014 / Auditing / MPhil / Unrestricted

An occurrence which is sometimes observed in a model based on dichotomous dependent variables is separation in the data. Separation in the data is when one or more of the independent variables can perfectly predict some binary outcome and it primarily occurs in small samples. There are three different mutually exclusive and exhaustive classes into which the data from a logistic regression can be classified: complete separation, quasi-complete separation and overlap. Separation (either complete or quasi-complete) in the data gives rise to a number of problems since it implies in nite or zero maximum likelihood estimates which are idealistic and does not happen in practice. In this dissertation the theory behind a logistic regression model, the definition of separation and different methods to deal with separation are discussed in part I. The methods that will be focused on are exact logistic regression, Firth s method which penalises the likelihood function and hidden logistic regression. In part II of this dissertation the three fore mentioned methods will be compared to one another. This will be done by applying each method to data sets which exhibit either complete or quasi-complete separation for different sample sizes and different covariate types. / Dissertation (MSc)--University of Pretoria, 2013. / Statistics / Unrestricted

Carbon-14, a radioactive nuclide, is used in many industrial applications. Due to its wide range of uses in industry, many workers are at risk of accidental internal exposure to 14C. Being a low energy beta emitter, 14C is not a significant external radiation hazard, but the internal consequences posed by 14C are important, especially because of its long half life of 5730 years. The current biokinetic model recommended by the International Commission on Radiological Protection (ICRP) is a conservative estimate of how radiocarbon is treated by the human body. The ICRP generic radiocarbon model consists of a single compartment representing the entire human body. This compartment has a biological half life of 40 days yielding an effective dose coefficient of 5.8×10-10 Sv Bq-1. This overestimates the dose of all radiocarbon compounds that have been studied. An improved model has been developed that includes and alimentary tract, a urinary bladder, CO2 model, and an "Other" compartment used to model systemic tissues. The model can be adapted to replicate any excretion curve and excretion pattern. In addition, the effective dose coefficient produced by the updated model is near the mean effective dose coefficient of carbon compounds that have been considered in this research. The major areas of improvement are: more anatomically significant, a less conservative dose coefficient, and the ability to manipulate the model for known excretion data. Due to the wide variety of carbon compounds, it is suggested that specific biokinetic models be implemented for known radiocarbon substances. If the source of radiocarbon is dietary, then the physiologically based model proposed by Whillans that splits all ingested radiocarbon compounds into carbohydrates, fats, and proteins should be used.

Comme de nombreux colloïdes, des nanoparticules métalliques recouvertes de ligands en suspension s’organisent au-delà d’une fraction volumique seuil et forment ce que l’on appelle un « supracristal ». Ce sont ainsi des systèmes modèles, déjà largement étudiés à partir de suspensions dans des solvants volatils, qui permettent de mieux comprendre l’auto-assemblage de sphères déformables. Les interactions qui conduisent à l’auto-assemblage sont couramment décrites par une compétition entre une attraction de van der Waals entre les cœurs métalliques et une répulsion entre les ligands qui va dépendre de l’affinité entre les ligands et le solvant. Un effet du solvant a déjà été observé sur l’auto-organisation de nano-objets. En mesurant par diffusion de rayons X aux petits angles le facteur de structure de suspensions de nanoparticules d’or greffées, j’ai pu sonder de façon systématique les interactions entre des nanoparticules en suspension avec plusieurs tailles de cœur, des ligands alcane-thiols de longueur différente et dans différents solvants à la fois volatils et non volatils. J’ai ainsi pu mettre en évidence une interaction attractive inattendue dans des alcanes linéaires flexibles et dont l’intensité augmente avec la longueur de l’alcane. Pour corréler les interactions entre particules à leur diagramme de phase, j’ai suivi le processus de cristallisation dans des suspensions en solvant volatil ou partiellement volatil ainsi qu’en émulsion, techniques qui permettent d’augmenter lentement la concentration en nanoparticules. Les interactions attractives induites par le solvant contribuent ainsi à la formation de supracristaux à de très faibles fractions volumiques. A de fortes concentrations, la structure des supracristaux ne dépend pas du solvant utilisé mais, à forte densité de greffage, du rapport R entre la longueur des ligands et le diamètre du cœur d’or. Pour un rapport R voisin de 0.7, la structure finale observée est cubique centrée, la structure à concentration intermédiaire étant cubique à faces centrées. Pour un rapport R deux fois plus petit, une structure originale a été mise en évidence. Il s’agit d’une structure hexagonale de grand paramètre de maille, analysée comme une phase de Frank et Kasper de type MgZn2 ou C14. C’est la première fois qu’une telle phase à empilement local tétraédrique est observée dans un système de sphères monodisperses molles. L’existence de cette phase ainsi que le rôle du rapport R a pu être interprétée en estimant quantitativement la compétition entre l’attraction de van der Waals forte et l’entropie des ligands. / As many colloids, metallic nanoparticles grafted with hydrophobic ligands self-assemble above a volume fraction threshold and thus build superlattices. These model systems, which are widely studied when suspended in volatile oils, enable a better understanding of soft spheres self-assembly.Interactions which lead to self-assembly are commonly described by the combination of van der Waals attraction with interaction between the ligand shells. The shell behavior is controlled by the ligand affinity with the solvent. An effect of the solvent on the self-assembly of nanoparticles has already been observed. Using a small angle X-ray scattering, I measured, through the structure factor, the interactions between gold nanoparticles grafted with alkanethiols in different oils, at various concentrations, for different lengths of ligands and core diameters. I noticed an attractive interaction when using flexible linear alkanes as solvent. It has also been shown that the attraction intensity increases with the solvent length.In order to correlate the interactions between particles to their phase diagram, I studied the crystallization process by concentrating nanoparticles using evaporation in capillaries or Ostwald ripening in emulsions. I showed that attractive interactions induced by the solvent lead to superlattices formation at very low volume fractions.At high concentrations, the superlattice structure depends on the ratio of the ligand length over the gold core diameter. For a ratio around 0.7, the final structure observed is body centered cubic, whereas at lower concentration, it is face centered cubic. When this ratio is halved, an unexpected structure is observed. It is a hexagonal structure with a large lattice parameter. It has been analyzed as a Frank and Kasper’s phase named MgZn2 or C14. It is the first time that this topologically close-packed structure is observed for monodisperse soft spheres. The existence of this phase and the role of the ratio R have been interpreted by considering quantitatively the competition between ligands entropy and the strong van der Waals attraction.

This article assesses the empirical relationship between per capita income growth fluctuations and the age-structured human capital variations across four groups of geographically clustered developed and developing countries from spatial perspective. We estimate a spatial Vector Autoregressive (VAR) model of income dynamics where the distance between countries is defined on relational space based on their similarity in appropriation tendency of human capital in the production processes. These distances are computed using a newly developed human capital data set which fully characterizes the demographic structure of human capital, and thus underlines the joint relevance of demography and human capital in economic growth. Spatial effects on growth interdependence and complementarity are then explored with respect to the proposed distance metrics. Our results imply that significant cross-country growth interdependence based on human capital distances exists among defined country groups suggesting the need for a cooperative policy programme among them. We also find that the relationship between economic growth and human capital is highly nonlinear as a function of the proposed human capital distance.

The paper analyses the relationship between succession and firm performance. Applying a non-parametric matching approach on a panel of roughly 4,000 Austrian family firms we evaluate the impact of past succession as well as future succession plans on employment growth. Analysing succession plans, we do not find a 'shadow of succession' effect. No significant difference in employment growth is found between firms that plan to transfer the firm in the next ten years and those who do not. In contrast, past succession exerts a significant and positive employment growth effect which becomes stronger over time. Thus, our findings provide support for the existence of a positive employment shadow after a transfer, whereas the shadow of succession hypothesis has to be rejected prior to transition. / Series: Discussion Papers SFB International Tax Coordination