University of Antwerp

About: University of Antwerp is a education organization based out in Antwerp, Belgium. It is known for research contribution in the topics: Population & Context (language use). The organization has 16682 authors who have published 48837 publications receiving 1689748 citations. The organization is also known as: Universiteit Antwerpen & UAntwerp.

Maximum-likelihood estimation of Rician distribution parameters

Abstract: The problem of parameter estimation from Rician distributed data (e.g., magnitude magnetic resonance images) is addressed. The properties of conventional estimation methods are discussed and compared to maximum-likelihood (ML) estimation which is known to yield optimal results asymptotically. In contrast to previously proposed methods, ML estimation is demonstrated to be unbiased for high signal-to-noise ratio (SNR) and to yield physical relevant results for low SNR.

Bidirectional transcripts of the expanded C9orf72 hexanucleotide repeat are translated into aggregating dipeptide repeat proteins

Abstract: Massive GGGGCC repeat expansion in the first intron of the gene C9orf72 is the most common known cause of familial frontotemporal lobar degeneration (FTLD) and amyotrophic lateral sclerosis (ALS). Despite its intronic localization and lack of an ATG start codon, the repeat region is translated in all three reading frames into aggregating dipeptide-repeat (DPR) proteins, poly-(Gly-Ala), poly-(Gly-Pro) and poly-(Gly-Arg). We took an antibody-based approach to further validate the translation of DPR proteins. To test whether the antisense repeat RNA transcript is also translated, we raised antibodies against the predicted products, poly-(Ala-Pro) and poly-(Pro-Arg). Both antibodies stained p62-positive neuronal cytoplasmic inclusions throughout the cerebellum and hippocampus indicating that not only sense but also antisense strand repeats are translated into DPR proteins in the absence of ATG start codons. Protein products of both strands co-aggregate suggesting concurrent translation of both strands. Moreover, an antibody targeting the putative carboxyl terminus of DPR proteins can detect inclusion pathology in C9orf72 repeat expansion carriers suggesting that the non-ATG translation continues through the entire repeat and beyond. A highly sensitive monoclonal antibody against poly-(Gly-Arg), visualized abundant inclusion pathology in all cortical regions and some inclusions also in motoneurons. Together, our data show that the GGGGCC repeat is bidirectionally translated into five distinct DPR proteins that co-aggregate in the characteristic p62-positive TDP-43 negative inclusions found in FTLD/ALS cases with C9orf72 repeat expansion. Novel monoclonal antibodies against poly-(Gly-Arg) will facilitate pathological diagnosis of C9orf72 FTLD/ALS.

Information Sharing and Financial Sector Development in Africa

Abstract: This study investigates the effect information sharing has on financial sector development in 53 African countries for the period 2004 to 2011. Information sharing is measured with private credit bureaus and public credit registries. Hitherto unexplored dimensions of financial sector development are employed, namely: financial sector dynamics of formalization, informalization, and non-formalization. The empirical evidence is based on Ordinary Least Squares (OLS) and Generalized Method of Moments (GMM). The following findings are established. Information-sharing bureaus increase (reduce) formal (informal/non-formal) financial sector development. In order to ensure that information-sharing bureaus improve (decrease) formal (informal/non-formal) financial development, public credit registries should have between 45.45 and 50% coverage while private credit bureaus should have at least 26.25% coverage.

Precipitation manipulation experiments - challenges and recommendations for the future

Abstract: Climatic changes, including altered precipitation regimes, will affect key ecosystem processes, such as plant productivity and biodiversity for many terrestrial ecosystems. Past and ongoing precipitation experiments have been conducted to quantify these potential changes. An analysis of these experiments indicates that they have provided important information on how water regulates ecosystem processes. However, they do not adequately represent global biomes nor forecasted precipitation scenarios and their potential contribution to advance our understanding of ecosystem responses to precipitation changes is therefore limited, as is their potential value for the development and testing of ecosystem models. This highlights the need for new precipitation experiments in biomes and ambient climatic conditions hitherto poorly studied applying relevant complex scenarios including changes in precipitation frequency and amplitude, seasonality, extremity and interactions with other global change drivers. A systematic and holistic approach to investigate how soil and plant community characteristics change with altered precipitation regimes and the consequent effects on ecosystem processes and functioning within these experiments will greatly increase their value to the climate change and ecosystem research communities. Experiments should specifically test how changes in precipitation leading to exceedance of biological thresholds affect ecosystem resilience and acclimation.