The case for the multi-species ecological system, with special reference to succession and stability

Multi-species life support system based on ecological theor

The tolerance of ambiguity as basic to the identity of the clinical psychologist

Inaugural lecture--Department of Psychology, Rand Afrikaans University, 26 October 1981It is imperative that the trainer of clinical psychologists be clear as to the identity of the clinical psychologist. Controversy and uncertainty exists concerning the definition of the identity of the clinical psychologist. On the one hand he is seen as a scientist, a tester of theories; in contrast as a practitioner who wants to help people in their ordinary lives. Taking a closer look at the essence of what the clinical psychologist does, it becomes clear that the scientist and the practitioner represent two incompatible systems of thought. The precision and control characterising the scientific endeavour seem to be irreconcilable with the intuitive and "open" communication of a typical clinical situation. Some influential clinical psychologists, in noting the ambivalence inherent in the identity of the clinical psychologist, have advocated a deliberate choice between the two identities. This has resulted in a polarization between two points of view: reason and emotion, thinking and feeling, science and practice are played off against one another at the cost of both. The point of view represented in this address is that polarization can only be harmful. It is stated that the ambivalent identity for the clinical psychologist should not only be accepted but also actively promoted, since it seems to be the best way to meet the reality of a clinical situation. It is furthermore pointed out that clinical psychology as a subject cannot develop if the clinical psychologist is unable to be scientist and practitioner simultaneously. Ways are suggested which could be followed by tutors towards training a clinical psychologist to maintain and tolerate his ambivalent role

Evaluating the time interval from diagnosis to fibrinolysis at centres in the drainage area of Tygerberg Hospital, Cape Town, South Africa

Background. ST-segment elevation myocardial infarction (STEMI) is one of the main contributors to morbidity and mortality in South Africa (SA). Timeous intervention by means of percutaneous coronary intervention (PCI) or fibrinolysis can significantly improve the outcome of STEMI.Objectives. To determine the median time interval between diagnosis and fibrinolysis in patients presenting to centres within the drainage area of Tygerberg Hospital, Cape Town, SA, and compare it with the European Society of Cardiology (ESC) recommendation of 10 minutes.Methods. A retrospective medical record review of patients presenting to the abovementioned centres between 1 March 2017 and 28 February 2018 was performed. The primary presenting centre, time between diagnosis and fibrinolysis and discharge medication were recorded, in addition to other relevant demographic information.Results. A total of 492 patients were identified, of whom 447 were included in the study. Three hundred and eighteen patients received fibrinolysis, of whom 18 (5.7%) were treated within 10 minutes of diagnosis. The median time interval between diagnosis and fibrinolysis was 67 (interquartile range (IQR) 32.5 -122.5) minutes.Conclusions. Most patients received fibrinolysis >10 minutes after diagnosis, which indicates suboptimal therapy when compared with the ESC guidelines. Future studies should investigate the factors prolonging this therapeutic delay

Characteristic Potentials for Mesoscopic Rings Threaded by an Aharonov-Bohm Flux

Electro-static potentials for samples with the topology of a ring and penetrated by an Aharonov-Bohm flux are discussed. The sensitivity of the electron-density distribution to small variations in the flux generates an effective electro-static potential which is itself a periodic function of flux. We investigate a simple model in which the flux sensitive potential leads to a persistent current which is enhanced compared to that of a loop of non-interacting electrons. For sample geometries with contacts the sensitivity of the electro-static potential to flux leads to a flux-induced capacitance. This capacitance gives the variation in charge due to an increment in flux. The flux-induced capacitance is contrasted with the electro-chemical capacitance which gives the variation in charge due to an increment in an electro-chemical potential. The discussion is formulated in terms of characteristic functions which give the variation of the electro-static potential in the interior of the conductor due to an increment in the external control parameters (flux, electro-chemical potentials). Paper submitted to the 16th Nordic Semiconductor Meeting, Laugarvatan, Iceland, June 12-15, 1994. The proceedings will be published in Physica Scripta.Comment: 23 pages + 4 figures, revtex, IBM-RC1955

Mycosin-1, a subtilisin-like serine protease of Mycobacterium tuberculosis, is cell wall-associated and expressed during infection of macrophages

BACKGROUND: Exported proteases are commonly associated with virulence in bacterial pathogens, yet there is a paucity of information regarding their role in Mycobacterium tuberculosis. There are five genes (mycP1-5) present within the genome of Mycobacterium tuberculosis H37Rv that encode a family of secreted, subtilisin-like serine proteases (the mycosins). The gene mycP1 (encoding mycosin-1) was found to be situated 3700 bp (four ORF's) from the RD1 deletion region in the genome of the attenuated vaccine strain M. bovis BCG (bacille de Calmette et Guérin) and was selected for further analyses due to the absence of expression in this organism. RESULTS: Full-length, 50 kDa mycosin-1 was observed in M. tuberculosis cellular lysates, whereas lower-molecular-weight species were detected in culture filtrates. A similar lower-molecular-weight species was also observed during growth in macrophages. Mycosin-1 was localized to the membrane and cell wall fractions in M. tuberculosis by Western blotting, and to the cell envelope by electron microscopy. Furthermore, M. tuberculosis culture filtrates were shown to contain a proteolytic activity inhibited by mixed serine/cysteine protease inhibitors and activated by Ca(2+), features typical of the subtilisins. CONCLUSIONS: Mycosin-1 is an extracellular protein that is membrane- and cell wall-associated, and is shed into the culture supernatant. The protein is expressed after infection of macrophages and is subjected to proteolytic processing. Although proteolytically active mycosin-1 could not be generated recombinantly, serine protease activity containing features typical of the subtilisins was detected in M. tuberculosis culture filtrates