Chain ladder method: Bayesian bootstrap versus classical bootstrap

The intention of this paper is to estimate a Bayesian distribution-free chain ladder (DFCL) model using approximate Bayesian computation (ABC) methodology. We demonstrate how to estimate quantities of interest in claims reserving and compare the estimates to those obtained from classical and credibility approaches. In this context, a novel numerical procedure utilising Markov chain Monte Carlo (MCMC), ABC and a Bayesian bootstrap procedure was developed in a truly distribution-free setting. The ABC methodology arises because we work in a distribution-free setting in which we make no parametric assumptions, meaning we can not evaluate the likelihood point-wise or in this case simulate directly from the likelihood model. The use of a bootstrap procedure allows us to generate samples from the intractable likelihood without the requirement of distributional assumptions, this is crucial to the ABC framework. The developed methodology is used to obtain the empirical distribution of the DFCL model parameters and the predictive distribution of the outstanding loss liabilities conditional on the observed claims. We then estimate predictive Bayesian capital estimates, the Value at Risk (VaR) and the mean square error of prediction (MSEP). The latter is compared with the classical bootstrap and credibility methods

Dimensioning of an European backbone network in OPNET WDM Guru

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“Only People Who Know It Here Speak Well of It...”: The Location of Social Housing in Brazilian Cities and Effects of Territorial Stigmatization

In Brazil, social housing estates have acquired a reputation as substandard housing and places of the poor. Throughout the second half of the 20th century, housing policies that were designed on a national and local level focused on the fight against the growth of favelas in Brazilian cities. Often, the inhabitants of favelas were resettled to public housing estates (conjuntos habitacionais) in the urban peripheries where they did not have access to infrastructures and public services. This has contributed much to the bad image of social housing. In their daily life, the residents are subjected to a multilayered process of stigmatization. This article considers a conjunto that was established in the central area of Belo Horizonte in the 1940s. Even though its location brought important advantages, the inhabitants suffer from the stigma of being dwellers of a housing complex (“moradores de conjunto”). By analyzing contemporary sources and oral history interviews, this article aims to contribute to the discussion about the location of social housing in Brazilian cities and the effects of territorial stigmatization. Furthermore, the focus is on recent developments which show that there are several ways how stigma can be reduced or even reversed

Linear Tetraphenylmethane-Based Thioether Oligomers Stabilising an Entire Gold Nanoparticle by Enwrapping

The design and synthesis of a novel linear thioether-based ligand subunit with a tetraphenylmethane core used in the stabilisation of gold nanoparticles (AuNPs) are presented. Mono-, tri, penta- and heptamers of the ligand have been synthesised and used to stabilise AuNPs by enwrapping. With the exception of the monomer, all ligands provide reliable long-term stability and redispersibility for the coated nanoparticles in common organic solvents. Despite variation of the oligomer length, all stable particles were of the same size within error tolerance (1.16±0.32 nm for the trimer, 1.15±0.30 nm for the pentamer, 1.17±0.34 nm for the heptamer), as investigated by transmission electron microscopy (TEM). These findings suggest that not only the number of sulfur atoms in the ligand, but also its bulkiness play a crucial role in stabilising the AuNPs. These findings are supported by thermogravimetric analysis (TGA), showing that AuNPs stabilised by the penta- or heptamer are passivated by a single ligand. Thermal stability measurements suggest a correlation between ligand coverage and thermal stability, further supporting these findings

Automobilität in Lateinamerika – eine historiographische Analyse

Although car-ownership matters to many Latin Americans and cars are nearly omnipresent in daily life in Latin American societies, very little is known about important aspects of the social and cultural histories of automobility in Latin America. However, in the last ten years, several historians have begun to approach the meanings of automobility in Latin American countries. This trend is closely connected to recent developments and new approaches in the international research on mobility, the latter of which I discuss in the first part of this essay. To proceed, I analyze the state of the art on the history of automobility in Latin America, focusing on the following aspects: the emergence of early Latin American car cultures, car and traffic-related social conflicts, and road building. In the last part I ponder on the question of how future studies might advance the state of research on automobility and offer new perspectives on central themes in Latin American history.Although car-ownership matters to many Latin Americans and cars are nearly omnipresent in daily life in Latin American societies, very little is known about important aspects of the social and cultural histories of automobility in Latin America. However, in the last ten years, several historians have begun to approach the meanings of automobility in Latin American countries. This trend is closely connected to recent developments and new approaches in the international research on mobility, the latter of which I discuss in the first part of this essay. To proceed, I analyze the state of the art on the history of automobility in Latin America, focusing on the following aspects: the emergence of early Latin American car cultures, car and traffic-related social conflicts, and road building. In the last part I ponder on the question of how future studies might advance the state of research on automobility and offer new perspectives on central themes in Latin American history.Although car-ownership matters to many Latin Americans and cars are nearly omnipresent in daily life in Latin American societies, very little is known about important aspects of the social and cultural histories of automobility in Latin America. However, in the last ten years, several historians have begun to approach the meanings of automobility in Latin American countries. This trend is closely connected to recent developments and new approaches in the international research on mobility, the latter of which I discuss in the first part of this essay. To proceed, I analyze the state of the art on the history of automobility in Latin America, focusing on the following aspects: the emergence of early Latin American car cultures, car and traffic-related social conflicts, and road building. In the last part I ponder on the question of how future studies might advance the state of research on automobility and offer new perspectives on central themes in Latin American history.Apesar da importância da posse de um carro e da onipresença do automóvel no cotidiano das sociedades latinoamericanas, por muito tempo os historiadores se engajaram pouco no estudo do tema da automobilidade. Contudo, na última década dedicaram-se ao estudo de assuntos relacionados ao automóvel. Esse desenvolvimento relaciona-se com tendências atuais na pesquisa internacional sobre a história da mobilidade, as quais discuto na primeira parte deste artigo. Na sequência analiso o estado da arte sobre a história da automobilidade na América Latina, focando nos seguintes aspectos: a formação de culturas automobilísticas nas primeiras décadas do século XX, os conflitos sociais em torno da automobilidade e a construção de estradas. Na última parte, apresento algumas perspectivas para pesquisas futuras e como estas podem contribuir para o avanço da historiografia sobre América Latina num sentido mais amplo

Model Uncertainty in Claims Reserving within Tweedie's Compound Poisson Models

In this paper we examine the claims reserving problem using Tweedie's compound Poisson model. We develop the maximum likelihood and Bayesian Markov chain Monte Carlo simulation approaches to fit the model and then compare the estimated models under different scenarios. The key point we demonstrate relates to the comparison of reserving quantities with and without model uncertainty incorporated into the prediction. We consider both the model selection problem and the model averaging solutions for the predicted reserves. As a part of this process we also consider the sub problem of variable selection to obtain a parsimonious representation of the model being fitte

Model uncertainty in claims reserving within Tweedie's compound Poisson models

In this paper we examine the claims reserving problem using Tweedie's compound Poisson model. We develop the maximum likelihood and Bayesian Markov chain Monte Carlo simulation approaches to fit the model and then compare the estimated models under different scenarios. The key point we demonstrate relates to the comparison of reserving quantities with and without model uncertainty incorporated into the prediction. We consider both the model selection problem and the model averaging solutions for the predicted reserves. As a part of this process we also consider the sub problem of variable selection to obtain a parsimonious representation of the model being fitted

Smart Urban simulation tools for planning decision support need smart data and smart data gathering methods

Urban growth is a challenge for most cities all over the world, especially in less developed countries. This tendency calls for smart/innovative instruments to foster sustainable urban development. Decision support for urban planning is required in order to reduce costs and resources to better accommodate new population, willing to move into urban areas. Latin American countries e.g. went from being predominantly rural to predominantly urban within a few decades, leading to high concentrations of urban population. This urban growth is expected to continue leading to severe financial stress for city budgets by providing the required infrastructure. AIT - Austrian Institute of Technology has been contracted by the Inter-American Development Bank (IDB) to develop a smart “Urban Infrastructure Development Simulator” (UIDS) – a tool to performe urban growth simulation and related infrastructure cost estimations, which can be used effordless to support urban planning decissions. Therefore an Agent-based simulation model representing the urban growth by estimating dwelling behavior of the cities’ today’s residents and future residents from outside the urban region was developed. This urban growth simulation tool is based on input data with different spatial and temporal resolution. Data from Geographical Information Systems, Remote Sensing as well as statistical data are used to simulate scenarios for future development paths. To support the urban planning process such kind of tools need to have a high flexibility in data management, e.g., the import of new (e.g., more accurate) data to calculate new scenarios. But beyond this common need, what if the data is not or only partially available, how can a data gathering process be supported by new tools and methods. The paper will introduce different innovative ways urban planners can be supported to gain new data, which can be used in tools as the UIDS. The approaches developed enable the urban planners to easily introduce important tacit knowledge about the city into the simulation tool. Another method will depict how citizens participation for data collection can be enabled. The paper will further elaborate in general which challenges have been encountered and which solutions reduce the problems using different temporal and spatial data. The results discussed are based on experiences gathered whithin several urban growth simulation projects performed for different regions in Europe and Latin America

Trends in antiretroviral use in pregnancy in the UK and Ireland, 2008–2018

Introduction: HIV treatment recommendations have evolved over time, reflecting both growing availability of new antiretrovirals and accumulating evidence on their safe and effective use. We analysed patterns of antiretroviral use among diagnosed pregnant women living with HIV delivering in the UK and Ireland between 2008 and 2018 using national surveillance data. Methods: All singleton pregnancies with known outcomes and known timing of antiretroviral initiation reported to the National Surveillance of HIV in Pregnancy and Childhood were included. Every individual instance of specific antiretroviral use was the unit of analysis in generating a snapshot of antiretroviral use overall and over calendar time. The final analysis was restricted to the 14 most frequently prescribed antiretrovirals. Results: There were 12 099 singleton pregnancies reported during 2008–2018 and a total of 38 214 individual uses of the 14 most commonly prescribed antiretrovirals, the majority of which were started before conception (70.9%). In 2008, 37.7% (482/1279) of pregnancies were conceived under treatment, reaching 80.9% (509/629) by 2018. Patterns of antiretroviral use have changed over time, particularly for third agents. Between 2008 and 2018 the most frequently used protease inhibitor shifted from lopinavir to darunavir, whereas use of integrase inhibitors increased steadily over time. Conclusions: These national surveillance data enable investigation of the ‘real-world’ use of antiretrovirals in pregnancy on a population level. Findings demonstrate mixed responsiveness of antiretroviral prescription to changes in pregnancy guideline recommendations and may also reflect changes in commissioning and in the characteristics of pregnant women living with HIV

Effect of natural aging on the chemical composition of norway spruce, fir, and european oak wood.

The chemical composition of a number of naturally aged construction wood samples of spruce, fir and oak was investigated. The content of lignin, polysaccharide, and extractives was determined using wet chemical and chromatographic methods. Differences to non-aged wood samples were found particularly found on oak wood samples with regard to lignin and polysaccharide content as well as to cellulose crystallinity. The composition of wood extractives of aged and non-aged wood samples revealed degradation processes due to oxidation and slight hydrolysis. The investigation showed that the relative content of the structural wood constituents depends on the sample age as well as the conditions they were aged under. The different degradation rates of those structural components may lead to contradictory results regarding their contents at certain degrees of aging. Cellulose crystallinity values are affected by extractives content