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  • 1
    Language: English
    In: Proceedings of the National Academy of Sciences of the United States of America, 04 April 2017, Vol.114(14), pp.E2802-E2803
    Description: In their recent article, Coyte et al. (1) use an innovative combination of microfluidic experiments, mechanistic models, and game theory to study the impact of physical microenvironments on the activity of bacteria in porous media. The authors find that hydrodynamics can profoundly affect how bacteria compete and evolve in these systems. They indicate that this conclusion could in principle have important implications for the management of a range of engineered and natural porous media. However, two aspects of the research significantly limit its relevance to practical applications, especially in soils and sediments.The first aspect is the premise that bacterial growth in porous media occurs within biofilms that cover pore walls uniformly. This assumption underlies the model used by Coyte et al. (1), and has clearly motivated the design of their experiments. However, biofilms are far from ubiquitous in natural porous media. In the pore space of unsaturated soils, where many bacteria live, such biofilms are typically not observed (2, 3). In saturated fine- to medium-textured porous media, numerous microscopic observations indicate that biofilms are the exception rather than the rule. Indeed, even when severe bioclogging occurs in such systems, bacterial cells are not located in continuous biofilms but instead aggregate preferentially at pore necks (4, 5). Various modeling efforts have shown conclusively that to describe the occasionally pronounced effects of bacteria on the hydrodynamics of saturated porous media, approaches assuming the presence of continuous biofilms are not satisfactory, even when biofilms are considered to be permeable, and models need to invoke the development of plugs of low permeability, obstructing the lumen of pores (6, 7). It is possible that Coyte et al.’s (1) conclusions would still stand upon consideration of such plugs, but this will need to be checked.The second aspect that decreases the appeal of Coyte et al.’s (1) results in practice is the fact that, even though their research claims to be related to microbial competition, it involves only bacteria. In real porous media, other microorganisms are unavoidably present (8) and may affect not only the competition and evolution of bacteria directly, but also the hydrodynamics of the pore space. Growing fungal hyphae (9) may transport bacteria (and archaea) from one portion of the pore space to another, as well as partially clog pores. Hydrodynamics may have a sizeable effect on the dynamics of protozoan predators (10), predatory bacteria, or viral particles (phages), all ubiquitous in natural porous media and directly influencing the fate of bacterial populations.In this context, Coyte et al.’s (1) research should be viewed as the exploration of one scenario, among several plausible ones, to account for the competition or evolution of bacteria in porous media. Their results, in particular related to the application of game theory, are interesting, but do not settle the many questions associated with what determines the level of microbial biodiversity found in subsurface environments. A complete description will require the development of more realistic models, and additional data associated with the physical, chemical, and microbial characteristics of microenvironments in real porous media.
    Keywords: Biological Evolution ; Environment
    ISSN: 00278424
    E-ISSN: 1091-6490
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  • 2
    Language: English
    In: International Journal of Nursing Studies, December 2016, Vol.64, pp.96-97
    Description: Baveye comments on a recent article by Duffy et al (2016) which present a well thought-out list of points to pay attention to in order to maximize the chances that a manuscript, submitted for publication, sail through the review process and eventually get printed. There is no doubt that this thorough roadmap will be extremely useful to individuals in many disciplines, and especially to young researchers who may find the mechanics of the publishing process. Nevertheless, as a more seasoned researcher and long-time editor, Baveye feels that this roadmap would be even more useful if it included an additional ingredient, which in some sense might be considered "the" most important one. Indeed, from my experience, provided of course a manuscript contain novel and technically-sound scholarship, the single most determining factor to speed up acceptance for publication is whether the text presents an appealing story.
    Keywords: Nursing
    ISSN: 0020-7489
    E-ISSN: 1873-491X
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  • 3
    Language: English
    In: Journal of Hydrology, 17 May 2012, Vol.438-439, pp.1-2
    Keywords: Geography
    ISSN: 0022-1694
    E-ISSN: 1879-2707
    Source: ScienceDirect Journals (Elsevier)
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  • 4
    Language: English
    In: Journal of Hydrology, 2011, Vol.406(3), pp.137-140
    Keywords: Hydrological Research ; Publishing ; Interdisciplinarity ; Sociological Aspects ; Scholarly Communication ; Geography
    ISSN: 0022-1694
    E-ISSN: 1879-2707
    Source: ScienceDirect Journals (Elsevier)
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  • 5
    Language: English
    In: The journal of physical chemistry. B, 07 June 2012, Vol.116(22), pp.6233-49
    Description: We simulate spin relaxation processes, which may be measured by either continuous wave or pulsed magnetic resonance techniques, using trajectory-based simulation methodologies. The spin-lattice relaxation rates are extracted numerically from the relaxation simulations. The rates obtained from the numerical fitting of the relaxation curves are compared to those obtained by direct simulation from the relaxation Bloch-Wangsness-Abragam-Redfield theory (BWART). We have restricted our study to anisotropic rigid-body rotational processes, and to the chemical shift anisotropy (CSA) and a single spin-spin dipolar (END) coupling mechanisms. Examples using electron paramagnetic resonance (EPR) nitroxide and nuclear magnetic resonance (NMR) deuterium quadrupolar systems are provided. The objective is to compare those rates obtained by numerical simulations with the rates obtained by BWART. There is excellent agreement between the simulated and BWART rates for a Hamiltonian describing a single spin (an electron) interacting with the bath through the chemical shift anisotropy (CSA) mechanism undergoing anisotropic rotational diffusion. In contrast, when the Hamiltonian contains both the chemical shift anisotropy (CSA) and the spin-spin dipolar (END) mechanisms, the decay rate of a single exponential fit of the simulated spin-lattice relaxation rate is up to a factor of 0.2 smaller than that predicted by BWART. When the relaxation curves are fit to a double exponential, the slow and fast rates extracted from the decay curves bound the BWART prediction. An extended BWART theory, in the literature, includes the need for multiple relaxation rates and indicates that the multiexponential decay is due to the combined effects of direct and cross-relaxation mechanisms.
    Keywords: Molecular Dynamics Simulation
    ISSN: 15206106
    E-ISSN: 1520-5207
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  • 6
    Language: English
    In: International Journal of Nursing Studies, 2011, Vol.48(1), pp.1-2
    Description: Editorial on the peer review process. Methods of encouraging academics to review manuscripts and ensure that they are properly rewarded and acknowledged are discussed and ensuring the quality of reviews is considered. [(BNI unique abstract)] 10 references
    Keywords: Bibliometrics ; Scientific Publishing ; Peer Review ; Research ; Nursing
    ISSN: 0020-7489
    E-ISSN: 1873-491X
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  • 7
    Language: English
    In: Ecological Modelling, 2011, Vol.222(12), pp.1998-2010
    Description: ► The individual-based INDISIM-SOM model is far more sensitive to some parameters than to others. ► Key parameters for the evolution of C and N are microbial maintenance, energy, and death probability. ► The nitrification rate, in particular, appears highly affected by the death probability. ► The sensitivity analysis indicates what simplification of the model is possible. ► It also shows which parameters need to be evaluated with more accuracy than is currently achievable. The fate of soil carbon and nitrogen compounds in soils in response to climate change is currently the object of significant research. In particular, there is much interest in the development of a new generation of micro-scale models of soil ecosystems processes. Crucial to the elaboration of such models is the ability to describe the growth and metabolism of small numbers of individual microorganisms, distributed in a highly heterogeneous environment. In this context, the key objective of the research described in this article was to further develop an individual-based soil organic matter model, INDISIM-SOM, first proposed a few years ago, and to assess its performance with a broader experimental data set than previously considered. INDISIM-SOM models the dynamics and evolution of carbon and nitrogen associated with organic matter in soils. The model involves a number of state variables and parameters related to soil organic matter and microbial activity, including growth and decay of microbial biomass, temporal evolutions of easily hydrolysable N, mineral N in ammonium and nitrate, CO and O . The present article concentrates on the biotic components of the model. Simulation results demonstrate that the model can be calibrated to provide good fit to experimental data from laboratory incubation experiments performed on three different types of Mediterranean soils. In addition, analysis of the sensitivity toward its biotic parameters shows that the model is far more sensitive to some parameters, i.e., the microbial maintenance energy and the probability of random microbial death, than to others. These results suggest that, in the future, research should focus on securing better measurements of these parameters, on environmental determinants of the switch from active to dormant states, and on the causes of random cell death in soil ecosystems.
    Keywords: Individual-Based Model ; Soil Microbial Activity ; Soil Organic Matter ; C and N Mineralization ; Microbial Parameters ; Environmental Sciences ; Ecology
    ISSN: 0304-3800
    E-ISSN: 1872-7026
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  • 8
    Language: English
    In: Ecological economics : the transdisciplinary journal of the International Society for Ecological Economics, 2013, pp. 231-235
    ISSN: 09218009
    Source: Deutsche Zentralbibliothek für Wirtschaftswissenschaften
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  • 9
    Language: English
    In: Ecological Economics, November 2013, Vol.95, pp.231-235
    Description: In the abundant literature dealing with the monetary valuation, or monetization, of ecosystem services (MES), with very few exceptions, the concept is presented as having emerged in 1997. In fact, there is a long history, starting in the late fifties but largely ignored, of sustained attempts to assign monetary values to nature's services. These early efforts encountered many conceptual and methodological roadblocks, which could not be resolved and led a number of researchers to argue that monetary valuation was not a fruitful approach. It is in that context that MES was hailed by some in 1997 as a promising way to integrate environmental goods and services into the logic of economic markets. Knowledge of the full timeline casts a very different light, in particular on the difficulties currently encountered in the practice of MES; far from being the expected growing pains of a young discipline, these difficulties turn out to be long-standing problems that have eluded solution over the last half-century and appear intrinsically unresolvable. This perspective suggests that, at this point, it is advisable to look at alternatives to MES for the integration of nature into economic decisions. All rights reserved, Elsevier
    Keywords: Ecosystem Services ; Valuation ; Commodification ; Nature'S Services ; Environmental Sustainability ; Environmental Sciences ; Ecology ; Economics
    ISSN: 0921-8009
    E-ISSN: 1873-6106
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  • 10
    Language: English
    In: Journal of Hazardous Materials, 21 March 2015, Vol.285, pp.137-139
    Description: In recent years, several authors have suggested repeatedly that visible and near-infrared reflectance spectroscopy (VNIRS) could be an advantageous alternative to traditional wet-laboratory methods for the measurement of heavy metal concentrations in soils. In this comment, we argue that, on the contrary, VNIRS is of limited practical use in such a context and should not serve as an excuse to get rid of direly needed laboratory facilities. The key reasons are that VNIRS spectra are irremediably insensitive to the presence of heavy metals, that the effect of soil moisture and surface rugosity on VNIR sensing still has to be satisfactorily accounted for, and finally that VNIRS probes an extremely thin layer of soil at the surface, which is generally irrelevant in terms of plant growth. Given these intrinsic limitations, it seems indicated to put the persistent VNIRS myth to rest, and to explore other measurement techniques that may have more potential.
    Keywords: Engineering ; Law
    ISSN: 0304-3894
    E-ISSN: 1873-3336
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