192 research outputs found
Approaches to modelling mineral weathering by fungi
No full textFungi are agents of geochemical change in the environment and play important roles in the soil, the plant-root zone, and in rock and mineral habitats. Modelling may serve as a tool to quantify fungal weathering under natural conditions. This paper provides a review of existing mycelial growth models and examines how these can be adapted to describe weathering by ectomycorrhizal and other fungi in mineral soil.<br/
Letter from Fordyce Grinnell, Jr. to John Muir, 1912 Apr 23.
Full text linkPasadena, California.April 23, 1912.Mr John Muir233 Formosa Ave.,Hollywood, Cal.My dear Sir:On Thursday evening, May 2, the Entolmological Club will meet at Christopher\u27s, 551 So. Broadway, Los Angeles, Prof. C. O. Esterly and Dr. Davidson will speak on the Oil Fly, Psilopa Petrolei, the larvae of which live in the crude petroleum near Los Angeles, the only organism which does so, as far as I know. There will be other communications and general discussion among the students of insect life of this vicinity, followed by a banquet.We would be very glad to have you present with us on this occassion, as a guest of honor. I think we can claim you as an entomologist, as there is a butterfly, Thecla muirii, named after you by Henry Edwards about the year051781881; and a very pretty little moth, Gyros muiri also named by Henry Edwards. We won\u27t ask you to speak, unless you would like to do so, and of course we would like to hear you. But we would just like to have you present, and have the pleasure of meeting you; And I am sure you would be glad to meet the rest of us, who are naturalists also.I sincerely hope you will let me know in the affirmative, and I would be glad to call for you and take you to the meeting if you would desire that.Yours very truly,Fordyce Grinnell, Jr.572 N. Marengo Ave.,Pasadena, Calif.05178https://scholarlycommons.pacific.edu/jmcl/32929/thumbnail.jp
Self-adjoint boundary-value problems on time-scales
Full text linkNOTE: THE MATHEMATICAL SYMBOLS IN THIS ABSTRACT CANNOT BE DISPLAYED CORRECTLY ON THIS PAGE. PLEASE REFER TO THE ABSTRACT IN THE ATTACHED FILE OR THE PUBLISHERS WEBSITE FOR AN ACCURATE DISPLAY. In this paper we consider a second order, Sturm-Liouville-type boundary-value operator of the form Lu := -[pur] + qu,on an arbitrary, bounded time-scale T, for suitable functions p, q, together with suitable boundary conditions. We show that, with a suitable choice of domain, this operator can be formulated in the Hilbert space L2(T ), in such a way that the resulting operator is self-adjoint, with compact resolvent (here,‘self-adjoint’ means in the standard functional analytic meaning of this term). Previous discussions of operators of this, and similar, form have described them as ‘self-adjoint’, but have not demonstrated self-adjointness in the standard functional analytic sense
Population structure and properties of Candida albicans, as determined by multilocus sequence typing
Full text linkWe submitted a panel of 416 isolates of Candida albicans from separate sources to multilocus sequence typing
(MLST). The data generated determined a population structure in which four major clades of closely related
isolates were delineated, together with eight minor clades comprising five or more isolates. By Fisher’s exact
test, a statistically significant association was found between particular clades and the anatomical source,
geographical source, ABC genotype, decade of isolation, and homozygosity versus heterozygosity at the mating
type-like locus (MTL) of the isolates in the clade. However, these associations may have been influenced by
confounding variables, since in a univariate analysis of variance, only the clade associations with ABC type and
anatomical source emerged as statistically significant, providing the first indication of possible differences
between C. albicans strain type clades and their propensity to infect or colonize different anatomical locations.
There were no significant differences between clades with respect to distributions of isolates resistant to
fluconazole, itraconazole, or flucytosine. However, the majority of flucytosine-resistant isolates belonged to
clade 1, and these isolates, but not flucytosine-resistant isolates in other clades, bore a unique mutation in the
FUR1 gene that probably accounts for their resistance. A significantly higher proportion of isolates resistant
to fluconazole, itraconazole, and flucytosine were homozygous at the MTL, suggesting that antifungal pressure
may trigger a common mechanism that leads both to resistance and to MTL homozygosity. The utility of MLST
for determining clade assignments of clinical isolates will form the basis for strain selection for future research
into C. albicans virulence
Spectral properties of non-local uniformly-elliptic operators
Full text linkIn this paper we consider the spectral properties of a class of non-local uniformly elliptic operators, which arise from the study of non-local uniformly elliptic partial differential equations. Such equations arise naturally in the study of a variety of physical and biological systems with examples ranging from Ohmic heating to population dynamics. The operators studied here are bounded perturbations of linear (local) differential operators, and the non-local perturbation is in the form of an integral term. We study the eigenvalues, the multiplicities of these eigenvalues, and the existence of corresponding positive eigenfunctions. It is shown here that the spectral properties of these non-local operators can differ considerably from those of their local counterpart. However, we show that under suitable hypotheses, there still exists a principal eigenvalue of these operators
to which is prefixed a short answer to Volney's contradictions on Ali-Bey's history and revolt ...
No full texttranslated from the original into English by the author. to which is prefixed a short answer to Volney's contradictions on Ali-Bey's history and revolt ... / by S.L. [Sauveur Lusignan] KosmopolitesBd. 2, Paginierung springt von S. 254 auf S. 25
The formulation of second-order boundary value problems on time scales
No full textWe reconsider the basic formulation of second-order, two-point, Sturm-Liouville-type boundary value problems on time scales. Although this topic has received extensive atten-tion in recent years, we present some simple examples which show that there are certain difficulties with the formulation of the problem as usually used in the literature. These difficulties can be avoided by some additional conditions on the structure of the time scale, but we show that these conditions are unnecessary, since in fact, a simple, amended formulation of the problem avoids the difficulties. Copyright © 2006 F. A. Davidson and B. P. Rynne. This is an open access article distrib-uted under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. 1
Mathematical modelling of mycelia: a question of scale
No full textRecent advances in systems biology have driven many aspects of biological research in a direction heavily weighted towards computational, quantitative and predictive analysis, based on, or assisted by mathematical modelling. In particular, mathematical modelling has played a significant role in the development of our understanding of the growth and function of the fungal mycelium. One of the main problems that faces modellers in this context is the choice of scale. In the study of fungal mycelia, the question of scale is expressed in an extreme manner: Their indeterminate growth habit ensures that the investigation of the growth and function of mycelial fungi has to consider scales ranging from the (sub) micron to the kilometer. An excellent and extensive review of the applications of mathematical modelling to fungal growth, conducted up to the mid-1990s, can be found in Prosser (1995). In this article, we will concentrate on work since that date, with the emphasis being on recent developments in understanding fungal mycelia at all scales
Bifurcation in systems of reaction-diffusion equations
No full textSIGLEAvailable from British Library Document Supply Centre- DSC:DX176888 / BLDSC - British Library Document Supply CentreGBUnited Kingdo
Berkeley Award Lecture: mathematical modelling of the form and function of fungal mycelia
No full textFungi are of fundamental importance in the terrestrial environment. They have roles as decomposers, plant pathogens, symbionts, and in elemental cycles. Fungi are often dominant, and in soil can comprise the largest pool of biomass (including other microorganisms and invertebrates). They also play a role in maintenance of soil structure due to their filamentous growth habit and exopolymer production. Despite their important roles in the biosphere, fungi are frequently neglected within broader environmental and microbiological spheres. Additionally, mycological interests can be somewhat fragmented between traditional subject boundaries. This multi-disciplinary volume explores the roles and importance of fungi in the environment. Particular emphasis is given to major research advances made in recent years as a result of molecular and genomic approaches, and in cell imaging and biology. Drawing together microbiologists, mycologists, and environmental scientists, this work is a unique account of modern environmental mycology, and a pivotal contribution to the field
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