Terrestrial and marine biodiversity provides the basis for both ecosystems functioning and numerous commodities or services that underpin human well-being. From several decades, alarming trends have been reported worldwide for both biodiversity and ecosystem services. Therefore the sustainable management of biodiversity requires a double viewpoint balancing ecological conservation with the welfare of human societies. Understanding the underlying trade-offs, synergies and interactions imposes the development of interdisciplinary researches and methods. In that respect, bio-economic or ecological economic modeling is likely to play a major role. The present paper intends to elicit the key features, strengths and challenges of bio-economic approaches especially in mathematical and computational terms. It first recall the main bio-economic methods, models and decisional instruments used in these types of analyses. Then the paper shows to what extent bio-economic sustainability lies between equilibrium, viability and optimality mathematical frameworks. It ends up by identifying new major challenges among which the operationalization of ecosystem based management, the precautionary principle and the implementation of governance are especially important. 相似文献
Microbial treatments of waste water can be done in membrane reactors. A membrane installed outside the reactor is used to separate bacteria from the treated effluent.
A new membrane reactor concept is presented. The separation membrane is introduced in the reactor and not outside as in a normal one. The membrane plays the role of a separator of two streams and is used at the same time as the immobilizing support for the bacteria.
The reactor keeps the bacteria active via a specific nutrient stream that is provided on one side of the membrane. The bacteria grow in and on the membrane where they form an active biofilm. The bacteria can treat the effluent on one side and can be kept active via the nutrient stream at the other side without contamination of the effluent by the nutrient.
In this work, the performance of the BICMER (Bacteria Immobilized Composite MEmbrane Reactor) is demonstrated via treatments of effluents containing heavy metals or organic xenobiotics.
For heavy metal removal Alcaligenes eutrophus CH34 bacteria were used. These bacteria induce a metal bioprecipitation process that results in the formation of crystalline metal carbonates, which are recovered on a separate column in the reactor. In this way metals can be recovered without disturbing the biofilm on the membrane. Metals such as Cd, Zn, Cu, Pb and Y can be reduced to less than 50 ppb. The metals Co, Ni, Pd and Ge are reduced to below 100 ppb.
For organic xenobiotics Alcaligenes eutrophus AE1308 bacteria or other strains (depending on the xenobiotic to be degraded) were used. This strain degrades the xenobiotic 3-chlorobenzoate (Cba) and 2,4-dichlorophenoxyacetic acid to CO2, H2O and chloride). Concentrations of 3 mM Cba could be reduced to less than 0.1 mM. For other toxic organic compounds, different biodegrading strains need to be used. 相似文献
The two-dimensional striation model consists of a nonlinear system of PDE's which arises in the modeling of the ionospheric plasma. The local-in-time existence of strong solutions is first proved using Banach's fixed point theorem. Then, under physically relevant assumptions, the system is shown to be nonlinearly unstable as soon as it is linearly unstable. Moreover, the instability occurs before the possible blow-up time of the solution. The proof relies on an earlier work of Hwang and Guo (2003
Hwang , H. J. ,
Guo , Y. ( 2003 ). On the dynamical Rayleigh–Taylor instability . Arch. of Rat. Mech. Anal. 167 : 235 – 253 .[Crossref], [Web of Science ®], [Google Scholar]). The first step of the proof is to investigate under which conditions the linearized system is unstable and to prove that its spectrum is bounded, by means of a variational formulation. The second one consists in constructing a family of solutions depending on the parameter δ measuring the smallness of the perturbation to the steady-state. Thanks to the boundedness of the linearized spectrum, this family of solutions is shown to be unstable by means of a power series expansion in δ. 相似文献
Inclusion of edible insects in human diets is increasingly promoted as a sustainable source of proteins with high nutritional value. While consumer acceptability remains the main challenge to their integration into Western food culture, the use of edible insects as meal and protein concentrate could decrease neophobia. The defatting of edible insects, mostly done with hexane, is the first step in producing protein ingredients. However, its impact on protein profiles and techno-functionality is still unclear. Consequently, this study compares the protein profiles of hexane-defatted and non-hexane-defatted yellow mealworm (Tenebrio molitor) meals and protein extracts, and evaluates the impact of hexane on protein solubility and foaming properties. Results showed that profiles for major proteins were similar between hexane-defatted and non-defatted samples, however some specific content differences (e.g., hexamerin 2) were observed and characterized using proteomic tools. Protein solubility was markedly lower for T. molitor meals compared to protein extracts. A large increase in the foaming capacity was observed for defatted fractions, whereas foam stability decreased similarly in all fractions. Consequently, although the hexane-defatting step was largely studied to produce edible insect protein ingredients, it is necessary to precisely understand its impact on their techno-functional properties for the development of food formulations. 相似文献
Due to their very poor prognosis and a fatal outcome, secondary brain tumors are one of the biggest challenges in oncology today. From the point of view of the early diagnosis of these brain micro- and macro-tumors, the sensitivity and specificity of the diagnostic tools constitute an obstacle. Molecular imaging, such as Positron Emission Tomography (PET), is a promising technique but remains limited in the search for cerebral localizations, given the commercially available radiotracers. Indeed, the [18F]FDG PET remains constrained by the physiological fixation of the cerebral cortex, which hinders the visualization of cerebral metastases. Tumor angiogenesis is recognized as a crucial phenomenon in the progression of malignant tumors and is correlated with overexpression of the neuropilin-1 (NRP-1) receptor. Here, we describe the synthesis and the photophysical properties of the new gallium-68 radiolabeled peptide to target NRP-1. The KDKPPR peptide was coupled with gallium-68 anchored into a bifunctional NODAGA chelating agent, as well as Cy5 for fluorescence detection. The Cy5 absorbance spectra did not change, whereas the molar extinction coefficient (ε) decreased drastically. An enhancement of the fluorescence quantum yield (φF) could be observed due to the better water solubility of Cy5. [68Ga]Ga-NODAGA-K(Cy5)DKPPR was radiosynthesized efficiently, presented hydrophilic properties (log D = −1.86), and had high in vitro stability (>120 min). The molecular affinity and the cytotoxicity of this new chelated radiotracer were evaluated in vitro on endothelial cells (HUVEC) and MDA-MB-231 cancer cells (hormone-independent and triple-negative line) and in vivo on a brain model of metastasis in a nude rat using the MDA-MB-231 cell line. No in vitro toxicity has been observed. The in vivo preliminary experiments showed promising results, with a high contrast between the healthy brain and metastatic foci for [68Ga]Ga-NODAGA-K(Cy5)DKPPR. 相似文献
In this article, we give a brief overview of our recent work on continuum mechanical modelling and simulation of microbial films. This comprises some classical tasks of applied mathematics such as computational fluid dynamics, analysis of partial differential equations, and mathematical biology. 相似文献
Many systems in nature are characterized by complex behaviour where large cascades of events, or avalanches, unpredictably
alternate with periods of little activity. Snow avalanches are an example. Often the size distribution f(s) of a system's
avalanches follows a power law, and the branching parameter sigma, the average number of events triggered by a single preceding
event, is unity. A power law for f(s), and sigma = 1, are hallmark features of self-organized critical (SOC) systems, and
both have been found for neuronal activity in vitro. Therefore, and since SOC systems and neuronal activity both show large variability, long-term stability and memory capabilities,
SOC has been proposed to govern neuronal dynamics in vivo. Testing this hypothesis is difficult because neuronal activity is spatially or temporally subsampled, while theories of
SOC systems assume full sampling. To close this gap, we investigated how subsampling affects f(s) and sigma by imposing subsampling
on three different SOC models. We then compared f(s) and sigma of the subsampled models with those of multielectrode local
field potential (LFP) activity recorded in three macaque monkeys performing a short term memory task. 相似文献
Using the formalism of second quantization in the occupation number representation, a model Hamiltonian of the form H = Hloc + Hnonloc + Hloc?nonloc is developed. Hloc describes the gas atom-phonon system when the gas atom is near the surface, and the phonon operators are only in this term. Hnonmloc describes the gas atom moving in a static potential with no bound states, and Hloc-nonloc couples these two parts of H. The method of solution is to diagonalize Hloc and then to embed it in the continuum of scattering states of Hnonloc. The model is designed so that this diagonalization can be performed essentially exactly for a large class of gas-metal systems. The procedure is illustrated with a simple example which nevertheless shows how multi-phonon processes can dominate in desorption. 相似文献