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Search Results: 1 - 10 of 3437 matches for " Krüger "
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Constraining Forces Causing the Meissner Effect  [PDF]
Ekkehard Krüger
Journal of Modern Physics (JMP) , 2017, DOI: 10.4236/jmp.2017.88074
Abstract: As shown in former papers, the nonadiabatic Heisenberg model presents a novel mechanism of Cooper pair formation which is not the result of an attractive electron-electron interaction but can be described in terms of quantum mechanical constraining forces. This mechanism operates in narrow, roughly half-filled superconducting bands of special symmetry and is evidently responsible for the formation of Cooper pairs in all superconductors. Here we consider this new mechanism within an outer magnetic field. We show that in the magnetic field the constraining forces produce Cooper pairs of non-vanishing total momentum with the consequence that an electric current flows within the superconductor. This current satisfies the London equations and, consequently, leads to the Meissner effect. This theoretical result is confirmed by the experimental observation that all superconductors, whether conventional or unconventional, exhibit the Meissner effect.
Mast Cells: The Key to Multiple Sclerosis?  [PDF]
Per G?ran Krüger
World Journal of Neuroscience (WJNS) , 2014, DOI: 10.4236/wjns.2014.42014
Abstract:

Mast cells are present in high numbers in the border-zones of the multiple sclerosis-plaques. They are located in small clusters along capillaries and venules, and they are more abundant in females than in men. Mast cells can be stimulated to release specific mediators such as histamine, resulting in oedema formation, as well as proteases that may cause demyelination, by several different activation mechanisms. We hypothesize that a putative mast cell activation may be induced by diet factor(s) as well as long lasting mental stress that may lead to the release of catestatin, as well as ACTH released from the pituitary gland. Given a natural flux of mast cell recovery and activation, a putative phenomenon of massive release of mediators and “silent” reload periods may explain the relapsing-remitting phases of multiple sclerosis.

Investigation of the Hyperfine Structure of Atomic Niobium (Nb I) Spectral Lines Based on the Lower Energy Levels at 22936, 23010, and 23048 cm-1  [PDF]
L. Windholz, S. Krger
Spectral Analysis Review (SAR) , 2018, DOI: 10.4236/sar.2018.62004
Abstract: The hyperfine (hf) structure constants of three atomic niobium energy levels in the energy range around 23000 cm-1 (at 22936.90, 23010.58, and 23048.58 cm-1) are known with only limited accuracy, and the constants of combining levels are sometimes even unknown. Thus we performed laser spectroscopic investigations in the wavelength range between 5600 and 6500 Å, and we excited altogether 16 transitions in which these lower levels are involved. Beside a more precise determination of the hf structure constants of the three lower levels (which were determined on several lines sharing a common upper level), these experiments led to the knowledge of the hf constants of nine levels with previously unknown constants. Beside these results, also the hf constants of 13 further energy levels are reported. For six of these levels, the constants were previously unknown.
Multiple Sclerosis: A Mast Cell Mediated Psycho-Somatic Disease?  [PDF]
Per G?ran Krüger
World Journal of Neuroscience (WJNS) , 2018, DOI: 10.4236/wjns.2018.84035
Abstract: This paper reviews evidence that the presence of mast cells in specific sites of central nervous system, suggesting inflammatory processes, may explain all the symptoms observed in multiple sclerosis. This hypothesis would be relatively easy to test.
LRRK2 in Parkinson's disease – drawing the curtain of penetrance: a commentary
Rejko Krüger
BMC Medicine , 2008, DOI: 10.1186/1741-7015-6-33
Abstract: Parkinson's disease (PD) is the most common neurodegenerative movement disorder, and has been regarded as a prototypic non-genetic disorder for a long time. First insight into the genetic contribution to the typical Parkinsonian phenotype came from large families with classical Mendelian inheritance of the disease trait. The discovery of disease-causing mutations in the alpha-synuclein gene for autosomal dominant forms and in the Parkin, PINK1 and DJ-1 gene for autosomal recessive forms of PD allowed a first insight into the molecular mechanisms that mediate neurodegeneration in PD. Heterozygous mutations in the alpha-synuclein gene and homozygous mutations in the Parkin, PINK1 and DJ-1 gene show, in general, full penetrance and account for less than 1% of all PD cases [1]. Thus, due to the small proportion of PD patients that carried mutations in the respective genes, genetic testing and counselling of presymptomatic mutation carriers was not relevant and common recommendations limited molecular testing to symptomatic individuals. These premises have now changed due to the identification and characterization of mutations in the LRRK2 gene in PD [2,3].Mutations in the LRRK2 gene encoding the leucine-rich, repeat kinase 2 protein are the most frequent genetic cause of PD known to date. Clinicogenetic studies clearly showed that the majority of all LRRK2 mutation carriers present with symptoms indistinguishable from idiopathic PD [4-7]. To date, more than 50 variants are known, but only about 10% have been proven pathogenic and account for approximately 2% of sporadic and 10% of familial PD cases [4,8,9]. Initially identified in large families with autosomal dominant inheritance of PD, it turned out that mutations in the LRRK2 gene were also found in patients with the sporadic form of the disease (without positive family history). Among these mutations, a glycine to serine exchange in position 2019 of the peptide sequence (G2019S) is the most frequent worldwide with f
Die plek van Empedokles in die metafisies-mistieke tradisie
JS Krüger
HTS Theological Studies/Teologiese Studies , 2007,
Abstract: This article argues that Empedocles was more than a pre-Socratic philosopher. His thinking was also essentially mystical and should be situated on a large map of metaphysical-mystical continuities with the following dimensions: A historically discernable cultural and religious pool, encompassing not only South-Eastern Europe, Asia Minor and Mediterranean Africa, but also the north-eastern Eurasian shamanic tradition, and India; an historically largely inaccesible esoteric tradition; a set of structural elements of the human psyche, running under and across historical religions through time; and the development of a new convergence of previously historically unconnected mystical traditions in the social and cultural circumstances of today. In particular, the article investigates similarities and differences between Empedocles and Indian (specifically Buddhist) views on various issues, such as the four roots and the cyclical dialectic of love and strife. In that context the article notes the remarkable interpretation of Empedocles by Peter Kingsley which seems to draw Empedocles closer to Buddhism, but without explicating this implication of his reception. HTS Theological Studies Vol. 63 (2) 2007: pp. 409-430
Algebraic Multigrid Preconditioning for Iterative Eigensolvers
Matthias Krüger
Archives of Transport , 2010, DOI: 10.2478/v10174-010-0006-1
Abstract: The paper presents a comparative study of iterative solvers for eigen- problems, which arise e.g. in solid mechanics or structural analysis. We consider problems obtained by discretization of elliptic and self-adjoint partial differential operators. Typically, only a few of the smallest eigen- values of these problems are to be computed. We discuss various gradient based preconditioned eigensolvers which make use of algebraic multigrid preconditioning. We present algorithms together with numerical results. Performance characteristics are derived by a comparison with the solution of test problems. We show that known advantages of algebraic multigrid preconditioning (e.g. for boundary-value problems with large jumps in the coefficients) transfer to the eigensolvers considered here.
The impact of black economic empowerment (BEE) on South African businesses: Focusing on ten dimensions of business performance
LP Krüger
Southern African Business Review , 2011,
Abstract: South African businesses need to adopt and comply with certain legislative measures aimed at black economic empowerment (BEE). BEE was introduced by the current ANC government in a bid to overcome the economic legacy of apartheid and to broaden participation in the economy, especially by those perceived to have been previously excluded or denied access. The Department of Trade and Industry (the dti) has been tasked with overseeing the implementation of BEE, and for this purpose has created a special BEE unit to regulate compliance and administer BEE scorecards. In an empirical survey, conducted in March/April of 2010 among the top local South African businesses ranging from small, medium to large multinational companies, the perceptions, thoughts and anticipations of 500 individual managers on the impact of BEE on ten selected dimensions of business performance were sought. Alarmingly, most of the respondents disagreed with the notion that BEE compliance would improve the performance of the companies they worked for, specifically with regard to overall and international competitiveness; service excellence and client satisfaction; quality; productivity; entrepreneurial spirit and innovation; production performance; human development; staff morale, business ethics and transparency; sales and access to markets; and financial performance. These sentiments were expressed despite the fact that the majority of respondents indicated that they as individuals could stand to benefit if the companies they were employed in became BEE-compliant.
Restructuring of Insolvent Corporations in Canada
JGA Krüger
Potchefstroom Electronic Law Journal/Potchefstroomse Elektroniese Regsblad , 2010,
Abstract:
Skrapnel (Willem Anker)
L Krüger
Tydskrif vir letterkunde , 2012,
Abstract: Skrapnel. Willem Anker. Pretoria: Protea Boekhuis, 2011. 74 pp. ISBN: 978-1-86919-109-3.
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