25,910 research outputs found
Gamma-ray spectrometry across the Upper Devonian basin succession at Kowala in the Holy Cross Mountains (Poland)
The Upper Devonian sequence at Kowala in the Holy Cross Mountains was logged using gamma-ray spectrometry,
for investigating the changes of oxygenation level in the Late Devonian basin. The Th/U ratio indicates that oxygen
levels were low throughout the Late Frasnian interval, with low peaks during the Kellwasser Events showing anoxic
conditions in the basin. The F-F boundary interval was also oxygen deficient, but there may have been a brief reoxygenation
at the boundary itself. By the Famennian crepida Zone, the basin gradually began to reoxygenate, but in the
trachytera Zone another anoxic event, the Annulata Event occurred, causing a bloom rather than extinction of specially
adapted taxa such as Guerichia. Thus the gamma-ray spectrometry data suggests that basinal anoxia prevailed
through much of the Late Frasnian. The F-F extinction might have been the result of prolonged stresses imposed on
the ecosystem, particularly during the euxinic Upper Kellwasser Event
Metaproteomics for analysis of microbial function in the environment
This report briefly describes the approach of using proteomic analyses to examine protein expression directly from environmental samples (termed metaproteomics). This approach has potential for solving one of the major challenges facing microbial ecologists, by providing insight of microbial function directly within samples
Gamma-ray spectrometry across the Upper Devonian basin succession at Kowala in the Holy Cross Mountains (Poland)
The Upper Devonian sequence at Kowala in the Holy Cross Mountains was logged using gamma-ray spectrometry,
for investigating the changes of oxygenation level in the Late Devonian basin. The Th/U ratio indicates that oxygen
levels were low throughout the Late Frasnian interval, with low peaks during the Kellwasser Events showing anoxic
conditions in the basin. The F-F boundary interval was also oxygen deficient, but there may have been a brief reoxygenation
at the boundary itself. By the Famennian crepida Zone, the basin gradually began to reoxygenate, but in the
trachytera Zone another anoxic event, the Annulata Event occurred, causing a bloom rather than extinction of specially
adapted taxa such as Guerichia. Thus the gamma-ray spectrometry data suggests that basinal anoxia prevailed
through much of the Late Frasnian. The F-F extinction might have been the result of prolonged stresses imposed on
the ecosystem, particularly during the euxinic Upper Kellwasser Event
Public participation and New Urbanism: a conflicting agenda?
The challenges to public participation in planning are numerous. Inclusive and equitable processes are recognised as an ideal in much planning theory and practice, yet this ideal is increasingly difficult to realise in today’s societies that comprise diverse and multiple publics. Within the wider sustainability debate, ‘New Urbanism’ has emerged as a pragmatic alternative to convention allow-density development. Concomitant with a range of prescribed physical outcomes, the New Urbanism movement advocates a process of ‘citizen-based participatory planning and design’. Charrettes, with urban design workshops, are the favoured tools for achieving this goal. However, it is argued that the adherence to a single type of participatory tool can be inconsistent with accepted ideals of participation processes and has several implications. Of particular concern is the role of the charrette planner or facilitator, a figure who has the potential to manipulate the public because of his/her inevitable allegiance to the New Urban agenda. In addition, the examination of a charrette process in a small New Zealand town raises several broader questions about the ability of the approach to address issues of inclusiveness and the recognition of difference, two fundamental elements of good participatory processes
Activity In Vitro of Clotrimazole against Canine Methicillin-Resistant and Susceptible Staphylococcus pseudintermedius
Emergence of multidrug-resistance in Staphylococcus pseudintermedius (SP) has increased interest in topical therapy as an alternative to systemic antibiotics in canine pyoderma. The antifungal imidazole, clotrimazole, is contained in numerous licensed canine ear preparations. Its in vitro activity against SP has not been evaluated, although previous studies have shown that the related imidazole, miconazole, has significant anti-staphylococcal efficacy. We therefore determined minimum inhibitory concentrations (MICs) of clotrimazole amongst 50 SP isolates (25 methicillin-resistant [MR]SP and susceptible [MS]SP) collected from dogs in Germany during 2010–2011 using an agar dilution method (CLSI VET01-A4). MICs amongst MRSP and MSSP were comparable (MIC50 and MIC90 = 1mg/L for both groups, p = 0.317); overall, 49 isolates had MIC = 1 mg/L and one had MIC = 0.5 mg/L. The relatively low MICs obtained in this study are likely to be exceeded by topical therapy and thus further clinical evaluation of clotrimazole use in canine superficial pyoderma and otitis externa caused by MRSP and MSSP is now warranted
NSV 11749: Symbiotic Nova, Not a Born-Again Red Giant
NSV 11749 is a little-studied variable star, discovered by W. J. Luyten,
which had a long-duration outburst around the year 1903, reaching blue
magnitude 12.5 at maximum. Following the outburst, it has apparently been
quiescent at about blue magnitude 17 for the past century. It was recently
suggested that NSV 11749 may have been a low- or intermediate-mass star that
underwent a final helium shell flash, making it temporarily a "born-again" red
giant. If so, it would be only the fourth known member of this class, along
with V605 Aql, FG Sge, and V4334 Sgr. However, our newly obtained optical and
near-IR spectra of the object show that it is instead a symbiotic binary, with
strong Balmer and He I-II emission lines, combined with a cool red-giant
companion of spectral type M1-2 III. The 1903 outburst was most likely a
symbiotic nova event, of which less than a dozen are known at present.Comment: 13 pages, 3 figures, Accepted for publication in PAS
Heterotrophic bacteria exhibit a wide range of rates of extracellular production and decay of hydrogen peroxide
© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Bond, R. J., Hansel, C. M., & Voelker, B. M. Heterotrophic bacteria exhibit a wide range of rates of extracellular production and decay of hydrogen peroxide. Frontiers in Marine Science, 7, (2020): 72, doi:10.3389/fmars.2020.00072.Bacteria have been implicated as both a source and sink of hydrogen peroxide (H2O2), a reactive oxygen species which can both impact microbial growth and participate in the geochemical cycling of trace metals and carbon in natural waters. In this study, simultaneous H2O2 production and decay by twelve species of heterotrophic bacteria were evaluated in both batch and flow-through incubations. While wide species-to-species variability of cell-normalized H2O2 decay rate coefficients [2 × 10–8 to 5 × 10–6 hr–1 (cell mL–1)–1] was observed, these rate coefficients were relatively consistent for a given bacterial species. By contrast, observed production rates (below detection limit to 3 × 102 amol cell–1 hr–1) were more variable even for the same species. Variations based on incubation conditions in some bacterial strains suggest that external conditions may impact extracellular H2O2 levels either through increased extracellular production or leakage of intracellular H2O2. Comparison of H2O2 production rates to previously determined superoxide (O2–) production rates suggests that O2– and H2O2 production are not necessarily linked. Rates measured in this study indicate that bacteria could account for a majority of H2O2 decay observed in aqueous systems but likely only make a modest contribution to dark H2O2 production.This research was supported by NSF grant OCE-1131734/1246174 to BV and CH
Application of functional analysis to perturbation theory of differential equations
The deviation of the solution of the differential equation y' = f(t, y), y(O) = y sub O from the solution of the perturbed system z' = f(t, z) + g(t, z), z(O) = z sub O was investigated for the case where f and g are continuous functions on I x R sup n into R sup n, where I = (o, a) or I = (o, infinity). These functions are assumed to satisfy the Lipschitz condition in the variable z. The space Lip(I) of all such functions with suitable norms forms a Banach space. By introducing a suitable norm in the space of continuous functions C(I), introducing the problem can be reduced to an equivalent problem in terminology of operators in such spaces. A theorem on existence and uniqueness of the solution is presented by means of Banach space technique. Norm estimates on the rate of growth of such solutions are found. As a consequence, estimates of deviation of a solution due to perturbation are obtained. Continuity of the solution on the initial data and on the perturbation is established. A nonlinear perturbation of the harmonic oscillator is considered a perturbation of equations of the restricted three body problem linearized at libration point
Investigating Nonlinearity: A Note on the Implementation of Hamilton's Methodology
In this paper we give an account of the new approach to nonlinear econometric modelling proposed by Hamilton (2001) and briefly describe some of the methods of nonlinear optimization that may be used in the Gauss computer program provided by Hamilton for the implementation of his methodology. The performance of this program is investigated using data relating to Hamilton's example concerning the US Phillips curve, two versions of the Gauss software and a range of alternative numerical optimization options and values for the important Gauss parameter _oprteps. Finally, the effects of changes in the sample data on the results produced by Hamilton's procedure are explored. The results presented suggest some clear conclusions, which will be of value to those contemplating working with Hamilton's new method.
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