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Search Results: 1 - 10 of 449958 matches for " J. C. Lamprecht "
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A comprehensive approach to the development of thinking skills
G. J. Rossouw,J. C. Lamprecht
Koers : Bulletin for Christian Scholarship , 1995, DOI: 10.4102/koers.v60i4.645
Abstract: The development of independent and innovative thinking entails much more than merely the acquisition of a series of thinking skills. A comprehensive approach based upon inter-disciplinary cooperation between, among others, the disciplines of philosophy, education and pscychology is needed. In such a comprehensive approach to the development of thinking skills the following factors that have a bearing on the acquisition of thinking skills should be addressed: The cultivation of a positive disposition towards the development of thinking. The creation of conditions conducive to the development of thinking. The cultivation of virtues that will dispose a person towards good thinking. An understanding of what good thinking entails. The teaching and assessment of thinking skills. In this article, these various factors and their bearing on the development of thinking skills are explored. A general theoretical framework for the development of thinking skills is proposed that can and should be translated to specific domains of knowledge or to specific human enterprises.
Hacker risk in e-commerce systems with specific reference to the disclosure of confidential information
C. Lamprecht
South African Journal of Information Management , 2010, DOI: 10.4102/sajim.v6i4.356
Diaporthaceae associated with root and crown rot of maize
S.C. Lamprecht,P.W. Crous,J.Z. Groenewald,Y.T. Tewoldemedhin
IMA Fungus , 2011,
Abstract: Several isolates of coelomycetous fungi with pigmented conidia were consistently isolated from diseased roots of Zea mays in irrigated plots monitored in the KwaZulu-Natal Province of South Africa. Based on their morphology, these isolates could be identified as representative of Stenocarpella macrospora, S. maydis, and Phaeocytostroma ambiguum. Although species of Stenocarpella are well-known as causal agents of cob and stalk rot and leaf blight of maize in South Africa, the occurrence and importance of P. ambiguum is less well documented and understood. To determine the role of P. ambiguum as a root pathogen of maize, pathogenicity tests were conducted under glasshouse conditions at 18 °C night and 28 °C day temperatures using a pasteurised soil, river sand and perlite medium and a 0.5 % sand-bran inoculum. Based on these results, P. ambiguum was shown to be a primary pathogen of maize, but to be less virulent than the positive control, S. maydis. Furthermore, to clarify the higher-level phylogeny of these fungal genera, isolates were subjected to DNA sequencing of the nuclear ribosomal DNA (ITS & LSU). Partial gene sequences of the translation elongation factor 1-alpha gene were added to confirm the species monophyly. To resolve the generic placement of Phaeocytostroma, additional species such as P. sacchari, P. plurivorum and P. megalosporum were also added to the analysis. Based on these results, Stenocarpella and Phaeocytostroma were shown to be two well defined genera, belonging to Diaporthales , Diaporthaceae, being closely allied to Phomopsis (Diaporthe). All three genera were also observed to form alpha as well as beta conidia, and although this phenomenon is well documented for Phomopsis and Phaeocytostroma, it is a new observation for Stenocarpella. In spite of the differences in conidial pigmentation, no support could be obtained for polyphyly in Diaporthaceae, suggesting that as observed in Botryosphaeriaceae (Botryosphaeriales), conidial pigmentation is not informative at the family level in Diaporthales.
Pharmaceutical characterization of solid and dispersed carbon nanotubes as nanoexcipients
Ivanova MV, Lamprecht C, Loureiro MJ, Huzil JT, Foldvari M
International Journal of Nanomedicine , 2012, DOI: http://dx.doi.org/10.2147/IJN.S27442
Abstract: rmaceutical characterization of solid and dispersed carbon nanotubes as nanoexcipients Original Research (2855) Total Article Views Authors: Ivanova MV, Lamprecht C, Loureiro MJ, Huzil JT, Foldvari M Published Date January 2012 Volume 2012:7 Pages 403 - 415 DOI: http://dx.doi.org/10.2147/IJN.S27442 Received: 20 October 2011 Accepted: 20 November 2011 Published: 26 January 2012 Marina V Ivanova1, Constanze Lamprecht1, M Jimena Loureiro1, J Torin Huzil1,2, Marianna Foldvari1 1School of Pharmacy, 2Faculty of Applied Mathematics, University of Waterloo, Waterloo, ON, Canada Background: Carbon nanotubes (CNTs) are novel materials with considerable potential in many areas related to nanomedicine. However, a major limitation in the development of CNT-based therapeutic nanomaterials is a lack of reliable and reproducible data describing their chemical and structural composition. Knowledge of properties including purity, structural quality, dispersion state, and concentration are essential before CNTs see widespread use in in vitro and in vivo experiments. In this work, we describe the characterization of several commercially available and two in-house-produced CNT samples and discuss the physicochemical profiles that will support their use in nanomedicine. Methods: Eighteen single-walled and multi-walled CNT raw materials were characterized using established analytical techniques. Solid CNT powders were analyzed for purity and structural quality using thermogravimetric analysis and Raman spectroscopy. Extinction coefficients for each CNT sample were determined by ultraviolet-visible near infrared absorption spectroscopy. Standard curves for each CNT sample were generated in the 0–5 μg/mL concentration range for dispersions prepared in 1,2-dichlorobenzene. Results: Raman spectroscopy and thermogravimetric analysis results demonstrated that CNT purity and overall quality differed substantially between samples and manufacturer sources, and were not always in agreement with purity levels claimed by suppliers. Absorbance values for individual dispersions were found to have significant variation between individual single-walled CNTs and multi-walled CNTs and sources supplying the same type of CNT. Significant differences (P < 0.01) in extinction coefficients were observed between and within single-walled CNTs (24.9–53.1 mL cm-1 mg-1) and multi-walled CNTs (49.0–68.3 mL cm-1 mg-1). The results described here suggest a considerable role for impurities and structural inhomogeneities within individual CNT preparations and the resulting spectroscopic properties of their dispersions. Conclusion: Raw CNT materials require thorough analytical workup before they can be used as nanoexcipients. This applies especially to the determination of CNT purity, structure, and concentration. The results presented here clearly demonstrate that extinction coefficients must be determined for individual CNT preparations prior to their use.
Emergency point-ofcare ultrasound training, credentialing and accreditation
H Lamprecht
Continuing Medical Education , 2012,
Abstract: No Absrtact.
Oxidativer Stress und Antioxidantien beim sportlichen Training
Lamprecht M
Journal für Ern?hrungsmedizin , 2010,
Abstract: Bei sportlicher Belastung kann es zu einer überproduktion an reaktiven Sauerstoff- und Stickstoffspezies (RONS) kommen. Diese überproduktion an RONS, mit einhergehender Sch digung molekularer Strukturen, wird als Oxidativer Stress bezeichnet. H ufig wird daher, im Zusammen-hang mit sportlichen Training und Wettkampf, die Verwendung von Antioxidantien-Supplementen empfohlen, um dem Auftreten von Oxidativem Stress vorzubeugen. Dieser Fachbericht widmet sich dem aktuellen wissenschaftlichen und praxisrelevanten Stand zum Thema.
The Roles of the Actin Cytoskeleton in Fear Memory Formation
Raphael Lamprecht
Frontiers in Behavioral Neuroscience , 2011, DOI: 10.3389/fnbeh.2011.00039
Abstract: The formation and storage of fear memory is needed to adapt behavior and avoid danger during subsequent fearful events. However, fear memory may also play a significant role in stress and anxiety disorders. When fear becomes disproportionate to that necessary to cope with a given stimulus, or begins to occur in inappropriate situations, a fear or anxiety disorder exists. Thus, the study of cellular and molecular mechanisms underpinning fear memory may shed light on the formation of memory and on anxiety and stress related disorders. Evidence indicates that fear learning leads to changes in neuronal synaptic transmission and morphology in brain areas underlying fear memory formation including the amygdala and hippocampus. The actin cytoskeleton has been shown to participate in these key neuronal processes. Recent findings show that the actin cytoskeleton is needed for fear memory formation and extinction. Moreover, the actin cytoskeleton is involved in synaptic plasticity and in neuronal morphogenesis in brain areas that mediate fear memory. The actin cytoskeleton may therefore mediate between synaptic transmission during fear learning and long-term cellular alterations mandatory for fear memory formation.
Suffridge's Convolution Theorem for Polynomials and Entire Functions Having Only Real Zeros
Martin Lamprecht
Mathematics , 2012,
Abstract: We present a Suffridge-like extension of the Grace-Szeg\"o convolution theorem for polynomials and entire functions with only real zeros. Our results can also be seen as a $q$-extension of P\'olya's and Schur's characterization of multiplier sequences. As a limit case we obtain a new characterization of all log-concave sequences in terms of the zero location of certain associated polynomials. Our results also lead to an extension of Ruscheweyh's convolution lemma for functions which are analytic in the unit disk and to new necessary conditions for the validity of the Riemann Conjecture.
Suffridge's convolution theorem for polynomials with zeros in the unit disk
Martin Lamprecht
Mathematics , 2014,
Abstract: In 1976 Suffridge proved an intruiging theorem regarding the convolution of polynomials with zeros only on the unit circle. His result generalizes a special case of the fundamental Grace-Szeg\"o convolution theorem, but so far it is an open problem whether there is a Suffridge-like extension of the general Grace-Szeg\"o convolution theorem. In this paper we try to approach this question from two different directions: First, we show that Suffridge's convolution theorem holds for a certain class of polynomials with zeros in the unit disk and thus obtain an extension of one further special case of the Grace-Szeg\"o convolution theorem. Second, we present non-circular zero domains which stay invariant under the Grace-Szeg\"o convolution hoping that this will lead to further analogs of Suffridge's convolution theorem.
Characterisation of Phomopsis spp. associated with die-back of rooibos (Aspalathus linearis) in South Africa
Johan C. Janse van Rensburg,Sandra C. Lamprecht,Johannes Z. Groenewald,Lisa A. Castlebury
Studies in Mycology , 2006,
Abstract: Die-back of rooibos (Aspalathus linearis) causes substantial losses in commercial Aspalathus plantations in South Africa. In the past, the disease has been attributed to Phomopsis phaseoli (teleomorph: Diaporthe phaseolorum). Isolates obtained from diseased plants, however, were highly variable with regard to morphology and pathogenicity. The aim of the present study was thus to identify the Phomopsis species associated with die-back of rooibos. Isolates were subjected to DNA sequence comparisons of the internal transcribed spacer region (ITS1, 5.8S, ITS2) and partial sequences of the translation elongation factor-1 alpha gene. Furthermore, isolates were also compared in glasshouse inoculation trials on 8-mo-old potted plants to evaluate their pathogenicity. Five species were identified, of which D. aspalathi (formerly identified as D. phaseolorum or D. phaseolorum var. meridionalis) proved to be the most virulent, followed by D. ambigua, Phomopsis theicola, one species of Libertella and Phomopsis, respectively, and a newly described species, P. cuppatea. A description is also provided for D. ambigua based on a newly designated epitype specimen
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