Natural Language Processing at the School of Information Studies for Africa

The lack of persons trained in computational linguistic methods is a severe obstacle to making the Internet and computers accessible to people all over the world in their own languages. The paper discusses the experiences of designing and teaching an introductory course in Natural Language Processing to graduate computer science students at Addis Ababa University, Ethiopia, in order to initiate the education of computational linguists in the Horn of Africa region

Spatiotemporal monitoring of rare and elusive saproxylic beetles - A pheromone based approach

Forest ecosystems are under severe pressure from global environmental changes and increasing demands of wood-related products. During the last century, intensified management regimes have led to the decline of many previously common forest habitats, with catastrophic effects for biodiversity. Many saproxylic beetles, which often play important roles as decomposers and food sources in natural ecosystems, are suffering population declines due to the losses and degradation of their forest habitats. As many of the species have become increasingly rare, or appear cryptic and elusive, it is often challenging to study their genuine distributions and habitat demands. In recent years, pheromone-based methodologies have begun to be applied for surveying such rare and threatened insects. In this thesis, I first identified the aggregation-sex pheromone components of three saproxylic beetles of Swedish conservation interest. In a second step, I utilised pheromone-based trapping methodologies to investigate how beetles with varying substrate and habitat demands fare in the Swedish forest landscape. By setting up large-scale monitoring studies across their distribution ranges in Southern Sweden, I was able to evaluate both their spatial and temporal population fluctuations. My results reveal large variability in species’ responses to modern forestry practices, seemingly dependent on differences in their spatiotemporal ecology. Through the high accuracy sampling, I was significantly able to alter our perception of the presence and abundance of several species within their distribution ranges. Overall, this work demonstrates the need for efficient monitoring methodologies for conservation of forest biodiversity

Heart failure with preserved ejection fraction in primary care

Background Heart failure with preserved ejection fraction (HFpEF) is a condition associated with low quality of life, high morbidity and mortality. It constitutes a diagnostic challenge and there is little evidence of effective treatments. In spite of its high prevalence and the fact that many (17-36%) of these patients are managed in Primary Care (PC) most of the studies on the condition were performed in Hospital Care (HC). Aims The aim of this thesis was to describe HFpEF in PC, its characteristics, comorbidities and mortality as well as further prognostic and diagnostic difficulties and potential underdiagnosis. Methods The initial three studies were based on the Swedish quality registry for Heart Failure (HF) patients (SwedeHF). Patients without echocardiographic results (16%) were excluded. A total of 1802 patients from PC and 7852 from HC, all with an Ejection Fraction (EF) ≥ 40% were studied to identify comorbidities, risk factors and outcomes, and to compare PC- with HC-patients in the first study. The second study analyzed the prognostic value of N-terminal Brain Natriuretic Peptide (NT-proBNP) in HFpEF-patients managed in PC. 924 patients; 360 patients with EF 40-49%, Heart Failure with Midrange Ejection Fraction, (HFmrEF) and 564 patients with EF≥50% (HFpEF). The third study identified gender differences and was based on the 1802 patients from Study 1, divided into HFmrEF and HFpEF. The fourth study was performed in Gustavsbergs PC centre. Ninetysix patients that had contacted the General Practitioner (GP) unit for one of the three common HF- symptoms breathlessness, tiredness or ankle swelling were included to find potential underdiagnosis and to evaluate an internet-based self-test for HF. Results HFpEF patients managed in PC were older and the majority were women, compared with patients managed in HC. Only 2.8% had no comorbidity and all-cause mortality after 1 year was 7.8%. Smoking, Chronic Obstructive Pulmonary Disease (COPD) Diabetes mellitus (DM), age and heart rate were shown to be independent risk factors for mortality in PC. Echocardiographc examinations are often missing. In matched controls there were more RAS-antagonists and betablockers prescribed in HC. Study I. There was a clear association between levels of NT-proBNP and mortality, but only on a group level. Numerous variables were associated with increased NT-proBNP and further independently with mortality. Study II. Men had higher age-adjusted mortality than women. In women with HFpEF more than half of the cases had another cause of death than cardiovascular diseases. The dominating causes of death were malignant diseases and respiratory diseases but altogether 13 different causes were identified. Study III. There was an underdiagnosis of HFpEF of 21%, all in women. We also found an acceptable accuracy of an internet-based self-test for HF. Study IV. Conclusion Patients with HFpEF in PC constitutes a heterogenous group with high age and many comorbidities that may interfere with the pathophysiology of HF and irrespectively affect both morbidity and mortality. The patients are older (mean 78 y.), the proportion of women is higher (46.7% vs 36.3 %) and they have other independent risk factors than those managed in HC. A single evidence-based treatment of HFpEF-patients is not available. The results of this thesis suggest that HFpEF-patients in PC have an age-related multi-organ damage with great need of careful diagnostic and individualized magement. There is a substantial risk for underdiagnosis

Explicit optimization of plan quality measures in intensity-modulated radiation therapy treatment planning

Conventional planning objectives in optimization of intensity-modulated radiotherapy treatment (IMRT) plans are designed to minimize the violation of dose-volume histogram (DVH) thresholds using penalty functions. Although successful in guiding the DVH curve towards these thresholds, conventional planning objectives offer limited control of the individual points on the DVH curve (doses-at-volume) used to evaluate plan quality. In this study, we abandon the usual penalty-function framework and propose planning objectives that more explicitly relate to DVH statistics. The proposed planning objectives are based on mean-tail-dose, resulting in convex optimization. We also demonstrate how to adapt a standard optimization method to the proposed formulation in order to obtain a substantial reduction in computational cost. We investigate the potential of the proposed planning objectives as tools for optimizing DVH statistics through juxtaposition with the conventional planning objectives on two patient cases. Sets of treatment plans with differently balanced planning objectives are generated using either the proposed or the conventional approach. Dominance in the sense of better distributed doses-at-volume is observed in plans optimized within the proposed framework, indicating that the DVH statistics are better optimized and more efficiently balanced using the proposed planning objectives

Gender, Productivity and the Nature of Work and Pay: Evidence from the Late Nineteenth-Century Tobacco Industry

Women have, on average, been less well-paid than men throughout history. Prior to 1900, most economic historians see the gender wage gap as a reflection of men's greater strength and correspondingly higher productivity. This paper investigates the gender wage gap in cigar making around 1900. Strength was rarely an issue, but the gender wage gap was large. Two findings suggest that employers were not sexist. First, differences in earnings by gender for workers paid piece rates can be fully explained by differences in experience and other productivity-related characteristics. Second, conditioning on those characteristics, women were just as likely to be promoted to the better paying piece rate section. Neither finding is compatible with a simple model of sex-based discrimination. Instead, the gender wage gap can be decomposed into two components. First, women were typically less experienced, in an industry in which experience mattered. Second there were some jobs that required strength, for which men were better suited. Because strength was so valuable in the other jobs at this time, men commanded a wage premium in the general labour market, raising their reservation wage. Hiring a man required the firm to pay a 'man's wage'. This implies that firms that were slow to feminise their time rate workforce ended up with a higher cost structure than those that made the transition more quickly. We show that firms with a higher proportion of women in their workforce in 1863 were indeed more likely to survive 35 years later.gender, productivity, discrimination, piece-rates, time-rates, labour markets, firm survival

Star Vars: Finding the optimal Value-at-Risk approach for the banking industry

This paper explores the concept of Value-at-Risk (VaR) through a comparative study of nonparametric and parametric models in order to find the best risk model for banks’ trading portfolios. The non-parametric methods consist of three different approaches: Simple Historical Simulation, Age Weighted Historical Simulation and Volatility Weighted Historical Simulation by means of the EWMA and GARCH models for forecasting volatility. The parametric methods comprise six different approaches: VaR based on the normal distribution, VaR with Student’s t-distribution, RiskMetrics, VaR with implied volatility and VaR with GARCH volatility dynamics (both assuming normality and t-distribution). The models are estimated and tested on the S&P500 and a hypothetical bank trading portfolio. The evaluation of the models follows the Christoffersen framework of testing for correct conditional coverage together with assessment of model performance according to the regulatory requirements of the Basel Accord. The general finding is that models with leptokurtic features and time-varying volatility perform the best, while naïve models assuming normality and/or without volatility dynamics in general display poor performance. The GARCH(1,1)-t model by far outperforms its competitors as it can correctly account for both correct unconditional coverage and volatility clustering. The implications of market risk regulation are explored and it is argued that the current regulatory environment might provide incentives for low-quality risk management practices with significant room for regulatory improvements

Migration, Marriage, and Social Mobility : Women in Sweden 1880-1900

We study the social mobility of women by looking at the connection between migration and marriage outcomes using complete count census data for Sweden. The censuses 1880-1900 have been linked at the individual level, enabling us to follow 100,000 women from their parental home to their new marital household. Marriage market imbalances were not an important push factor for migration but we find a strong association between migration distance and marriage outcomes, both in terms of overall marriage probabilities and in terms of partner selection. These results highlight the importance of migration for women’s social mobility during industrialization

Pushing and Pulling : A population based approach to analysing the historical determinants of internal migration

This paper contributes to the literature on internal migration by estimating parameters for push and pull factors by modelling the complete migration decision. Using data based on individuals linked between the complete Swedish censuses of 1880 and 1890, we consider both the push factors which determined whether an individual choose to leave their origin and the pulls factors which attracted migrants to specific destinations. The analysis includes both male and female migrants and takes into account the effect of individual, family, and location specific characteristics . Moreover, we consider all possible origins and destinations for internal migrants

The effect of different disturbance treatments on tree production, competition, shortroot presence and ectomycorrhizal colonisation in Ericaceae-feathermoss boreal forests

In many northern boreal stands, forest floor vegetation constitutes a considerable part of total biomass and production, and consequently is likely to be critical in determining tree seedling growth. This study was conducted in a greenhouse with seedlings grown in intact soil profiles consisting of a minimum coverage of 90% of Pleurozium schreberi and 30% of Vaccinium myrtillus vegetation. I investigated the effect of three different disturbance treatments, (I) burning using a propane flame thrower to remove all vegetation and the uppermost portion of the humus of the profile; (II) trimming of all mosses and V. myrtillus at the height of the interface between the brown and green parts of mosses; and (III) control left intact, on the performance of monocultures and tree seedling mixtures of Pinus sylvestris, Betula pendula and Populus tremula by assessing shoot and root biomass, short root occurrence and mycorrhizal colonisation. The results of the different disturbance treatments on seedlings response variables was generally weak although P. sylvestris and P. tremula showed significantly higher values of biomass in fire treated vegetation compared to intact vegetation. B. pendula did not show any effects on total or root biomass across treatments but showed an increased shoot length and shoot to root ratio in intact vegetation compared to other treatments. The effect of disturbance in seedling mixtures on relative performance of the different tree species was not strong enough to influence the strength of their interactions. P. tremula seemed to be quite uncompetitive with other species and this was especially evident for seedlings grown in association with B. pendula. The production of short roots was generally higher in seedling mixtures compared to monocultures and in more intense disturbed treatments. Higher short root production in seedling mixtures possibly indicates lower nutrient availability when grown in association with different neighbours compared to monocultures. More than 95 % of seedling short roots independent of tree species were colonised by mycorrhiza and most of the EM morphotypes found showed great host specificity. The results of this study shows that ground vegetation of P. schreberi interfere with performance of P.sylvestris and P. tremula seedlings while the effect on B. pendula is more unclear and more study on this topic and the effect of seedling mixtures is needed