Crystalluria and Urolithiasis in a Relatively Stone-Free Population

The occurrence of renal stone in South African blacks is extremely rare. Whites however are prone to calculi to the same extent as that reported in other Western communities. The nature of the particulate material and crystalluria in urine samples from the two population groups were investigated using a Coulter Counter and scanning electron microscope. In addition, 10 calculi obtained from black patients over a 5 year period were analysed. The particle size distribution curves obtained for normal black and white males were identical. The curves for normal black and white females were also identical but different from those for males. Black male stone formers had larger particles than their controls while the single black female stone former investigated had particles of the same size as female controls, but in greater numbers. Scanning electron microscopy revealed profuse amounts of crystalline NaCl, KCl and other salts in the urinary sediments of blacks. These were not observed in the specimens from whites nor in the black stone formers\u27 urines. Analysis of the calculi identified chemical and ultrastructural features similar to those observed in stones from whites. The hypothesis that the lower incidence of stone disease in blacks may be due to a high Na/Ca ratio is supported by our findings. It is suggested that various salts play a role in lowering the stone forming potential of such urines by a competitive substitution mechanism in which lattice calcium is displaced by sodium. It is also suggested that when urinary stone formation does occur in blacks, it does so via the same physicochemical mechanisms as in any other race group

Die hermeneuse van die skrif met die oog op hedendaagse kerklik-etiese vraagstukke

Ons verstaan Hermeneutiek in die tradisionele sin. Ons gebruik die term dus nie in die sin van die sg. Nuwere Hermeneutiek, wat bykans die hele teologie onder “Hermeneutiek” as die hele proses van “verstaan” van die Skrifte wil insluk nie

New approximations for the cone of copositive matrices and its dual

We provide convergent hierarchies for the cone C of copositive matrices and its dual, the cone of completely positive matrices. In both cases the corresponding hierarchy consists of nested spectrahedra and provide outer (resp. inner) approximations for C (resp. for its dual), thus complementing previous inner (resp. outer) approximations for C (for the dual). In particular, both inner and outer approximations have a very simple interpretation. Finally, extension to K-copositivity and K-complete positivity for a closed convex cone K, is straightforward.Comment: 8

Learning to imitate facial expressions through sound

The question of how young infants learn to imitate others’ facial expressions has been central in developmental psychology for decades. Facial imitation has been argued to constitute a particularly challenging learning task for infants because facial expressions are perceptually opaque: infants cannot see changes in their own facial configuration when they execute a motor program, so how do they learn to match these gestures with those of their interacting partners? Here we argue that this apparent paradox mainly appears if one focuses only on the visual modality, as most existing work in this field has done so far. When considering other modalities, in particular the auditory modality, many facial expressions are not actually perceptually opaque. In fact, every orolabial expression that is accompanied by vocalisations has specific acoustic consequences, which means that it is relatively transparent in the auditory modality. Here, we describe how this relative perceptual transparency can allow infants to accrue experience relevant for orolabial, facial imitation every time they vocalise. We then detail two specific mechanisms that could support facial imitation learning through the auditory modality. First, we review evidence showing that experiencing correlated proprioceptive and auditory feedback when they vocalise – even when they are alone – enables infants to build audio-motor maps that could later support facial imitation of orolabial actions. Second, we show how these maps could also be used by infants to support imitation even for silent, orolabial facial expressions at a later stage. By considering non-visual perceptual domains, this paper expands our understanding of the ontogeny of facial imitation and offers new directions for future investigations

Statistics of matrix elements of local operators in integrable models

We study the statistics of matrix elements of local operators in the basis of energy eigenstates in a paradigmatic integrable many-particle quantum theory, the Lieb-Liniger model of bosons with repulsive delta-function interaction. Using methods of quantum integrability we determine the scaling of matrix elements with system size. As a consequence of the extensive number of conservation laws the structure of matrix elements is fundamentally different from, and much more intricate than, the predictions of the eigenstate thermalization hypothesis for generic models. We uncover an interesting connection between this structure for local operators in interacting integrable models, and the one for local operators that are not local with respect to the elementary excitations in free theories. We find that typical off-diagonal matrix elements $\langle\boldsymbol{\mu}|O|\boldsymbol{\lambda}\rangle$ in the same macro-state scale as $\exp(-c^{ O}L\ln(L)-LM^{O}_{\boldsymbol{\mu},\boldsymbol{\lambda}})$ where the probability distribution function for $M^{O}_{\boldsymbol{\mu},\boldsymbol{\lambda}}$ are well described by Fr\'echet distributions and $c^{O}$ depends only on macro-state information. In contrast, typical off-diagonal matrix elements between two different macro-states scale as $\exp(-d^{ O}L^2)$, where $d^{O}$ depends only on macro-state information. Diagonal matrix elements depend only on macro-state information up to finite-size corrections.Comment: 30 pages, 40 figure

Severe acute necrotizing pancreatitis associated with lipoprotein lipase deficiency in childhood

An 11-year-old girl with lipoprotein lipase deficiency experienced recurring episodes of abdominal pain. She initially underwent appendectomy for suspected appendicitis; however, the appendix was normal. Pancreatitis was subsequently identified as the cause of her pain

Learning to belong: Navigating liminal spaces between disciplinary and teaching identities

The continuous professional learning of academics as university teachers is a national imperative in South Africa. At our university, a Postgraduate Diploma in Education (Higher Education) was introduced in 2015 with the aim to professionalise university teaching through a formal qualification. Students (i.e., candidates) must transition in two ways: firstly, from being disciplinary specialists to being students again; and secondly, into the community of scholarly teaching in higher education. This article examines the liminality experienced by candidates as they navigate the programme and learn to belong to a new scholarly teaching community. Drawing on empirical data collected from graduates and programme coordinators, the authors track candidates’ shifting identities and showcase how, though initially turbulent and unsettling, the process of learning to belong to a new teaching identity can be rewarding and enriching. The authors conclude by discussing the conditions required to enable candidates to acquire a strong university-teacher identity