Relating Methanogen Community Structure and Anaerobic Digester Function

Much remains unknown about the relationships between microbial community structure and anaerobic digester function. However, knowledge of links between community structure and function, such as specific methanogenic activity (SMA) and COD removal rate, are valuable to improve anaerobic bioprocesses. In this work, quantitative structure–activity relationships (QSARs) were developed using multiple linear regression (MLR) to predict SMA using methanogen community structure descriptors for 49 cultures. Community descriptors were DGGE demeaned standardized band intensities for amplicons of a methanogen functional gene (mcrA). First, predictive accuracy of MLR QSARs was assessed using cross validation with training (n = 30) and test sets (n = 19) for glucose and propionate SMA data. MLR equations correlating band intensities and SMA demonstrated good predictability for glucose (q2 = 0.54) and propionate (q2 = 0.53). Subsequently, data from all 49 cultures were used to develop QSARs to predict SMA values. Higher intensities of two bands were correlated with higher SMA values; high abundance of methanogens associated with these two bands should be encouraged to attain high SMA values. QSARs are helpful tools to identify key microorganisms or to study and improve many bioprocesses. Development of new, more robust QSARs is encouraged for anaerobic digestion or other bioprocesses, including nitrification, nitritation, denitrification, anaerobic ammonium oxidation, and enhanced biological phosphorus removal

A sequential data assimilation approach for the joint reconstruction of mantle convection and surface tectonics

International audienceWith the progress of mantle convection modelling over the last decade, it now becomes possible to solve for the dynamics of the interior flow and the surface tectonics to first order. We show here that tectonic data (like surface kinematics and seafloor age distribution) and mantle convection models with plate-like behaviour can in principle be combined to reconstruct mantle convection. We present a sequential data assimilation method, based on suboptimal schemes derived from the Kalman filter, where surface velocities and seafloor age maps are not used as boundary conditions for the flow, but as data to assimilate. Two stages (a forecast followed by an analysis) are repeated sequentially to take into account data observed at different times. Whenever observations are available, an analysis infers the most probable state of the mantle at this time, considering a prior guess (supplied by the forecast) and the new observations at hand, using the classical best linear unbiased estimate. Between two observation times, the evolution of the mantle is governed by the forward model of mantle convection. This method is applied to synthetic 2-D spherical annulus mantle cases to evaluate its efficiency. We compare the reference evolutions to the estimations obtained by data assimilation. Two parameters control the behaviour of the scheme: the time between two analyses, and the amplitude of noise in the synthetic observations. Our technique proves to be efficient in retrieving temperature field evolutions provided the time between two analyses is 10 Myr. If the amplitude of the a priori error on the observations is large (30 per cent), our method provides a better estimate of surface tectonics than the observations, taking advantage of the information within the physics of convection

Application of cellular automata method to simulate the hot deformation behavior of a dual phase titanium alloy

A mathematical model based on the Eshelby theory and using the cellular automata method (CA) is developed to study microstructure evolution during forging of two-phase alloys. Specifically, the method is applied to the case of near alpha titanium alloy, IMI834, mainly used in the high-pressure parts of axial compressors of the most recent gas turbine engines. Viscoplastic laws are used to describe the flow behavior of this alloy for equixed  microstructures. The results obtained by CA models can reasonably well describe the material behavior both in the high temperature beta phase and in the two phase alpha + beta region. Experimental data of hot compression in the pure beta field are exploited in order to quantify the thermomechanical behavior of this phase, then processing in the alpha + beta field are used to calculate a phase behavior. Comparisons between the numerical modelling results and the experimental ones indicates that the CA method has a good capability for predicting the influence of forging conditions on the local and global mechanical characteristics of IMI834 alloy

Synthesis and Characterization of New Ceramic Thermoelectrics Implemented in a Thermoelectric Oxide Module

Novel thermoelectric oxides were developed, produced, and characterized to demonstrate their promising thermoelectric conversion potential in a thermoelectric converter. Four-leg thermoelectric oxide modules were fabricated by combining p- and n-type oxide thermoelements made of pressed polycrystalline GdCo0.95Ni0.05O3 and CaMn0.98Nb0.02O3, respectively. In these modules, the p- and n-type thermoelements were connected electrically in series and thermally in parallel. The materials were joined by electrical contacts consisting of a Ag/CuO composite material. Fairly good thermal contacts were ensured by pressing the thermoelements between alumina substrates. Cross-sections of the alumina/Ag-CuO mixture/thermoelement interface were investigated by scanning electron microscopy. The temperature distribution across the module was monitored using K-type thermocouples and a micro-infrared (IR) camera. The open-circuit voltage and the load voltages of the module were measured up to a temperature difference of ΔT=500K while keeping the temperature of the cold side at 300K. The output power and internal resistance were calculated. The characteristics of the module evaluated from electrical measurements were compared with respective values of the p- and n-type leg materials. An output power of 0.04W at ΔT=500K led to a power density of ~0.125W/cm3, where the volume of thermoelectric material was determined by a cross-section of 4mm×4mm and a leg length of 5m

Evaluation des sources de polluants susceptibles d'impacter les ouvrages de gestion des eaux pluviales – Diagnostic exhaustif à l'échelle du territoire nantais

International audienceTo offset the effects of soil sealing and to deal with stormwater management issue s , cities have adopted BMPs (Best Management Practices) for twenty years . Many facilities exist on urban areas and h ave proved to be efficient on a hydrological point of view, but questions remain about pollutants. Under the Matriochkas project, w h ich focuses on performances of stormwater management facilities in terms of retention of pollutants, an inventory on retention and infiltration basins and swales is conducted throughout the Nantes metropole territory. An exhaustive diagnosis of sources of pollutants is carried out on the facilities identifi ed in this inventory, using a methodology based on spatial analysis of geographic data. More specifically, contributive area of facilities is identified by an automatic method based on drainage networks. The description of these contributive areas in terms of geographic data (land use, human activities such as road traffic , and practices ), and literature data on emissions of pollutants in urban areas, makes it possible to estimate potential pollutant loads which discharge into these facilities.Afin de compenser les effets de l'imperméabilisation des sols et pour répondre à la problématique de gestion des eaux pluviales, les collectivités se tournent depuis une vingtaine d'années vers les techniques alternatives. De nombreux ouvrages existent sur les territoires urbains, et si leurs performances hydrologiques sont connues, leur rôle vis-à-vis de la rétention des polluants l'est moins. Dans le cadre du projet Matriochkas, qui s'intéresse aux performances des ouvrages de gestion à la source vis-à-vis de la rétention des polluants, un recensement des bassins de rétention et d'infiltration ainsi que des noues est mené sur l'ensemble de l'agglomération nantaise. Un diagnostic exhaustif des sources de pollution est réalisé sur les ouvrages identifiés dans ce recensement, en utilisant une méthodologie basée sur l'exploitation de données géographiques. Cette méthodologie consiste à déterminer la zone contributive des ouvrages en développant une méthode automatique qui s'appuie sur les réseaux de drainage. La description de ces zones contributives à partir de données géographiques (occupation du sol, activités anthropiques dont le trafic routier, et usages) et de données de la littérature relatives aux émissions de polluants sur les surfaces urbaines, permet d'estimer a priori les flux de polluants déversés dans ces ouvrages

Constraining Absolute Plate Motions Since the Triassic

The absolute motion of tectonic plates since Pangea can be derived from observations of hotspot trails, paleomagnetism, or seismic tomography. However, fitting observations is typically carried out in isolation without consideration for the fit to unused data or whether the resulting plate motions are geodynamically plausible. Through the joint evaluation of global hotspot track observations (for times <80 Ma), first‐order estimates of net lithospheric rotation (NLR), and parameter estimation for paleo–trench migration (TM), we present a suite of geodynamically consistent, data‐optimized global absolute reference frames from 220 Ma to the present. Each absolute plate motion (APM) model was evaluated against six published APM models, together incorporating the full range of primary data constraints. Model performance for published and new models was quantified through a standard statistical analyses using three key diagnostic global metrics: root‐mean square plate velocities, NLR characteristics, and TM behavior. Additionally, models were assessed for consistency with published global paleomagnetic data and for ages <80 Ma for predicted relative hotspot motion, track geometry, and time dependence. Optimized APM models demonstrated significantly improved global fit with geological and geophysical observations while performing consistently with geodynamic constraints. Critically, APM models derived by limiting average rates of NLR to ~0.05°/Myr and absolute TM velocities to ~27‐mm/year fit geological observations including hotspot tracks. This suggests that this range of NLR and TM estimates may be appropriate for Earth over the last 220 Myr, providing a key step toward the practical integration of numerical geodynamics into plate tectonic reconstructions

Comparison of local pole assignment methods

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76770/1/AIAA-20171-818.pd

Reflection Scattering Matrix of the Ising Model in a Random Boundary Magnetic Field

The physical properties induced by a quenched surface magnetic field in the Ising model are investigated by means of boundary quantum field theory in replica space. Exact boundary scattering amplitudes are proposed and used to study the averaged quenched correlation functions.Comment: 37 pages (Latex), including 16 figures, one reference adde

Use of stable isotope fingerprints to assign wintering origin and trace shorebird movements along the East Atlantic Flyway

Migratory connectivity can be defined as the flux of individuals or populations among areas between stages of an animal's life cycle. Many shorebird species perform long-distance migrations and while moving between breeding and wintering grounds, they depend on a network of intermediate wetlands (stopover sites) where populations of different origins extensively overlap. The difficulty to discriminate such populations represents a serious obstacle to the identification of the links between breeding or wintering areas and stopover sites, and also precludes the estimation of demographic parameters for each population. In this study, we test if linear discriminant models based on stable carbon and nitrogen isotope ratios in toenails can he used to identify populations of several shorebird species of different wintering origins overlapping at two stopover sites of the East Atlantic Flyway. In addition, we evaluate the ability of this approach to infer migratory phenological patterns of shorebirds. Linear discriminant analyses performed overall well in distinguishing the isotopic signals of birds from wintering areas (in France, Portugal, Morocco, Mauritania and Guinea-Bissau) most species, correctly classifying over 80% (n = 542) of all wintering individuals sampled at these areas. Assignment rates of shorebirds captured during spring migration were also high (96%, n=323) at the Tejo estuary, Portugal, but lower (40%, 0 = 185) at Marennes-Oleron Bay in France, and also differed among species. A large proportion of spring migrants captured in Portugal and France were assigned to Banc d' Arguin in Mauritania, the most important wintering area in the flyway. Phenological patterns derived for dunlins (Calidris alpina), common ringed plovers (Charadrius hiaticula) and grey plovers (Pluvialis squatarola) suggest that the first northward migrants started arriving at the Tejo estuary during the second half of March, with peaking numbers occurring during April or May.</p