External quality assessment of urinary methylmalonic acid quantification - results of a pilot study

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Localizable invariants of combinatorial manifolds and Euler characteristic

It is shown that if a real value PL-invariant of closed combinatorial manifolds admits a local formula that depends only on the f-vector of the link of each vertex, then the invariant must be a constant times the Euler characteristic.Comment: 14 pages, 5 figures. Some arguments are improved and one picture is adde

Contemplating the approach RAU’s founders towards radically transforming Afrikaans speaker identity in taking economic responsibility

Abstract: This discussion on the former Rand Afrikaans University (RAU) covers the founding years of the University from 1955 to 1975. What should become clear from the contemplations is that the establishment of RAU in 1968 (today the University of Johannesburg), was not driven by the increase in the population of white Afrikaans speakers on the Witwatersrand or to act as a force against the liberal influences of the University of the Witwatersrand (Wits). The philosophy behind the establishment of RAU was mainly to reposition and empower white Afrikaans speakers with the education required to ensure that they could take their place in particularly the Witwatersrand as economic heartland of South Africa, and South Africa in general. Part of this approach by the founders was to create and develop RAU to become the most modern Afrikaans university of its time, providing quality teaching and learning of high local and international standards. The prominence of being a university driven by specific ideals contributed to the forming of the Afrikaans speaker’s identity in education and the national economy. As examples, this discussion mainly emphasises some new teaching methods introduced at the time, visibly blending with a refreshed view on the architectural design to accommodate the philosophical ideals envisioned for RAU. The founders’ vision was for RAU to become an educational instrument towards transforming white Afrikaans speaker identity within a modernised context

Kalman Filters for Time Delay of Arrival-based Source Localization

In this work, we propose an algorithm for acoustic source localization based on time delay of arrival (TDOA) estimation. In earlier work by other authors, an initial closed-form approximation was first used to estimate the true position of the speaker followed by a Kalman filtering stage to smooth the time series of estimates. In the proposed algorithm, this closed-form approximation is eliminated by employing a Kalman filter to directly update the speaker\u27s position estimate based on the observed TDOAs. In particular, the TDOAs comprise the observation associated with an extended Kalman filter whose state corresponds to the speaker\u27s position. We tested our algorithm on a data set consisting of seminars held by actual speakers. Our experiments revealed that the proposed algorithm provides source localization accuracy superior to the standard spherical and linear intersection techniques. Moreover, the proposed algorithm, although relying on an iterative optimization scheme, proved efficient enough for real-time operation

The Use of Natural Genetic Diversity in the Understanding of Metabolic Organization and Regulation

The study of metabolic regulation has traditionally focused on analysis of specific enzymes, emphasizing kinetic properties, and the influence of protein interactions and post-translational modifications. More recently, reverse genetic approaches permit researchers to directly determine the effects of a deficiency or a surplus of a given enzyme on the biochemistry and physiology of a plant. Furthermore, in many model species, gene expression atlases that give important spatial information concerning the quantitative expression level of metabolism-associated genes are being produced. In parallel, “top-down” approaches to understand metabolic regulation have recently been instigated whereby broad genetic diversity is screened for metabolic traits and the genetic basis of this diversity is defined thereafter. In this article we will review recent examples of this latter approach both in the model species Arabidopsis thaliana and the crop species tomato (Solanum lycopersicum). In addition to highlighting examples in which this genetic diversity approach has proven promising, we will discuss the challenges associated with this approach and provide a perspective for its future utility