pinecone/core-2020-05-10-deduplication huggingface dataset:
Micro-confinement of bacteria into w/o emulsion droplets for rapid detection and enumeration

International audienceToday, rapid detection and identification of bacteria in microbiological diagnosis is a major issue. Reference methods usually rely on growth of microorganisms, with the drawback of lengthy time-to-result. The method provides global information on a clonal population that is known to be inhomogeneous relative to metabolic states and activities. Therefore, there may be a significant advantage of methods that allow characterisation of individual bacteria from a large population, both for test time reduction and the clinical value of the characterisation. We report here a method for rapid detection and real-time monitoring of the metabolic activities of single bacteria. Water-in-oil emulsions were used to encapsulate single Escherichia coli cells into picolitre (pL)-sized microreactor droplets. The glucuronidase activity in each droplet was monitored using the fluorogenic reporter molecule MUG (4-methylumbelliferyl- - d-glucuronide) coupled to time-lapse fluorescence imaging of the droplets. Such bacterial confinement provides several major advantages. (1) Enzymatic activities of a large number of single bacterium-containing droplet could be monitored simultaneously, allowing the full characterisation of metabolic heterogeneity in a clonal population. We monitored glucuronidase enzymatic activity and growth over ∼200 single bacteria over a 24-h period. (2) Micro-confinement of cells in small volumes allows rapid accumulation of the fluorescent metabolite, hence decreasing the detection time. Independent of the initial concentration of bacteria in the sample, detection of the presence of bacteria could be achieved in less than 2 h. (3) Considering the random distribution of bacteria in droplets, this method allowed rapid and reliable enumeration of bacteria in the initial sample. Overall, the results of this study showed that confinement of bacterial cells increased the effective concentration of fluorescent metabolites leading to rapid (2 h) detection of the fluorescent metabolites, thus significantly reducing time to numeration
Molecular hydrogen in the damped Lyman α system towards GRB 120815A at z = 2.36

International audienceWe present the discovery of molecular hydrogen (H2), including the presence of vibrationally-excited H2* in the optical spectrum of the afterglow of GRB 120815A at z = 2.36 obtained with X-shooter at the VLT. Simultaneous photometric broad-band data from GROND and X-ray observations by Swift/XRT place further constraints on the amount and nature of dust along the sightline. The galactic environment of GRB 120815A is characterized by a strong DLA with log(N(H i)/cm-2) = 21.95 ± 0.10, prominent H2 absorption in the Lyman-Werner bands (log (N(H2)/cm-2) = 20.54 ± 0.13) and thus a molecular gas fraction log f(H2) = -1.14 ± 0.15. The distance d between the absorbing neutral gas and GRB 120815A is constrained via photo-excitation modeling of fine-structure and meta-stable transitions of Fe ii and Ni ii to d = 0.5 ± 0.1 kpc.  The DLA metallicity ([Zn/H] = -1.15 ± 0.12), visual extinction (AV ≲ 0.15 mag) and dust depletion ([Zn/Fe] = 1.01 ± 0.10) are intermediate between the values of well-studied, H2-deficient GRB-DLAs observed at high spectral resolution, and the approximately solar metallicity, highly-obscured and H2-rich GRB 080607 sightline. With respect to N(H i), metallicity, as well as dust-extinction and depletion, GRB 120815A is fairly representative of the average properties of GRB-DLAs. This demonstrates that molecular hydrogen is present in at least a fraction of the more typical GRB-DLAs, and H2 and H2* are probably more wide-spread among GRB-selected systems than the few examples of previous detections would suggest. Because H2* transitions are located redwards of the Lyman α absorption, H2* opens a second route for positive searches for molecular absorption also in GRB afterglows at lower redshifts and observed at lower spectral resolution. Further detections of molecular gas in GRB-DLAs would allow statistical studies, and, coupled with host follow-up and sub-mm spectroscopy, provide unprecedented insights into the process and conditions of star-formation at high redshift
Phytostabilization of As, Sb and Pb by two willow species (S. viminalis and S. purpurea) on former mine technosols

International audienceIt is becoming increasingly popular to use phytoremediation methods for the reclamation of mine sites containing metal(loid)s. This study aims to assess the phytostabilization ability of two willow species (Salix viminalis and Salix purpurea) on technosols from a former gold mining site presenting polymetallic contamination (As, Sb and Pb). Different reconstituted soils using a mixture of the litter and the technosol collected on this previously mined site and a non-contaminated control garden soil were investigated in a 2 laboratory mesocosm. The physico-chemical soil parameters and the total metal(loid)s content in pore water were determined. After 45 days of growth, roots, leaves and stems from the two willow species were harvested. The biomass, metal(loid) concentrations and the mineral mass were determined for the different plant organs. Both Salix species were able to develop root systems on the different reconstituted soils and a variable aboveground biomass according to the soil composition. As, Sb and Pb accumulated mainly in the Salix rhizosphere. S. purpurea was more efficient in accumulating As in the plant's upper parts than S. viminalis. S. viminalis showed an ability to transfer Pb and Sb to its shoots whereas S. purpurea did not translocate these elements
The EPN-TAP protocol for the Planetary Science Virtual Observatory

International audienceA Data Access Protocol has been set up to search and retrieve Planetary Science data in general. This protocol will allow the user to select a subset of data from an archive in a standard way, based on the IVOA Table Access Protocol (TAP). The TAP mechanism is completed by an underlying Data Model and reference dictionaries. This paper describes the principle of the EPN-TAP protocol and interfaces, underlines the choices that have been made, and discusses possible evolutions
Accounting robustly for instantaneous chemical equilibriums in reactive transport: A numerical method and its application to liquid-liquid extraction modeling

International audienceReactive transport equations are used in numerous application fields: CO2 or nuclear waste storage monitoring, separation process in chemical engineering. We present a general method to account robustly for instantaneous equilibriums in reactive transport. This method is adapted to all kind of hydraulic transport models including 1D to 3D convection-diffusion equations. This leads to the resolution of a bound constrained system of Differential Algebraic Equations (DAE). The algebraic constraints come from the adjunction of mass action laws related to the equilibriums, whereas the bounds account for the positivity of the computed quantities. In order to solve the numerical system associated with our method, we use an adaptation of the DASSL solver, CDASSL, that can handle the resolution of bound constrained DAE systems. We present an application of this method to liquid-liquid extraction modeling. Numerical experiments demonstrate the interest of using the CDASSL solver to ensure the bound constraints are satisfied
Confinement effects on water structure in membrane lyotropic phases

International audienceThe change of the water structure in aqueous solutions of the tri-ethyleneglycol mono n-decyl ether (C10E3) was studied by micro Raman scattering. The results obtained on the O-H stretching band show that the behavior of the hydrogen bonding (H-bonds) water network can be used as a probe to follow the lamellar (Lα) to sponge (L3) phase transition. In the lamellar phase, the stack of the surfactant molecules aggregated into a two-dimensional structure (membrane) acts as a soft confinement system for the H-bond water network of which the regular tetrahedral structure is perturbed. The change of the planar organization of the membranes to a highly disordered and infinite array of bilayers in the sponge phase amplifies the surface of contact between amphiphilic surfactant and water molecules which drives a strong disruption of the regular tetrahedral H-bonding water networ
Quantifying the role of sandy-silty sediments in generating slope failures during earthquakes: example from the Algerian margin

International audienceThe Algerian margin is a seismically active region, where during the last century, several large magnitude earthquakes took place. This study combines geotechnical and sedimentological data with numerical modelling to quantitatively assess the present-day slope stability of the Algerian margin. Geotechnical laboratory tests, such as cyclic triaxial tests, oedometric tests and vane shear tests were carried out on sediment cores collected on the study area. The liquefaction potential of a sediment column located about 30 km from the Boumerdès earthquake epicentre of 21st May 2003 was evaluated theoretically for an earthquake of M w = 6.8. We show that thin sand and silt beds such as those described on recovered sediment cores are the main cause of sediment deformation and liquefaction during earthquakes. Numerical calculations showed that the slope failure may occur during an earthquake characterised by a PGA in excess of 0.1g, and also that, under a PGA of 0.2g liquefaction could be triggered in shallow silty-sandy deposits. Moreover, comparison of the predicted slope failure with failure geometries inferred from seafloor morphology showed that earthquakes and subsequent mass movements could explain the present-day morphology of the study area
Operating an atom interferometer beyond its linear range

20 pages, 8 figuresInternational audienceIn this paper, we show that an atom interferometer inertial sensor, when associated to the auxiliary measurement of external vibrations, can be operated beyond its linear range and still keep a high acceleration sensitivity. We propose and compare two measurement procedures (fringe fitting and nonlinear lock) that can be used to extract the mean phase of the interferometer when the interferometer phase fluctuations exceed $2\pi$. Despite operating in the urban environment of inner Paris without any vibration isolation, the use of a low noise seismometer for the measurement of ground vibrations allows our atom gravimeter to reach at night a sensitivity as good as $5.5\times10^{-8}$g at 1 s. Robustness of the measurement to large vibration noise is also demonstrated by the ability of our gravimeter to operate during an earthquake with excellent sensitivity. Our high repetition rate allows for recovering the true low frequency seismic vibrations, ensuring proper averaging. Such techniques open new perspectives for applications in other fields, such as navigation and geophysics
Relationships between type I and type II chondrules: Implications on chondrule formation processes

International audienceIn unequilibrated chondrites, the ferromagnesian silicates in chondrules exhibit wide ranges of mg# = Mg/(Mg + Fe), allowing to sub-divide porphyritic chondrules into either type I (mg# > 0.9) or type II (mg# < 0.9). Although both chondrule types formed under oxidizing conditions relative to the canonical solar nebula, it is generally inferred that type II chondrules formed in more oxidizing conditions than type I. In order to check whether this redox difference was established during chondrule formation, or reflects differences in their precursors, we have undertaken a set of experiments aimed at heating type I olivine-rich (A) chondrule proxy, i.e. forsterite + Fe metal + Ca-Mg-Si-Al glass mixtures, under oxidizing conditions. We show that high temperature (isothermal) oxidation of type IA-like assemblages is a very efficient and rapid process (e.g., few tens of minutes) to form textures similar to type IIA chondrules. Due to the rapid dissolution of Fe metal blebs, a FeO increase in the melt and in combination with the dissolution of magnesian olivine allows the melt to reach ferroan olivine saturation. Crystallization of ferroan olivine occurs either as new crystal in the mesostasis or as overgrowths on the remaining unresorbed forsterite grains (relicts). Interruption of this process at any time before its completion by rapid cooling allows to reproduce the whole range of textures and chemical diversity observed in type A chondrules, i.e., from type I to type II.Several implications on chondrule formation processes can be inferred from the presented experiments. Type I chondrules or fragments of type I chondrules are very likely the main precursor material involved in the formation of most type II chondrules. Formation of porphyritic olivine type II chondrules is very likely the result of processes generating crystal growth by chemical disequilibrium at high temperature rather than processes generating crystallization only by cooling rates. This questions the reliability of chondrule thermal history (e.g., cooling rate values) hitherto inferred for producing porphyritic textures from dynamical cooling rate experiments only. Type A chondrule formation can be a very fast process. After periods of sub-isothermal heating or slow cooling (< 50 K/h) as short as several tens of minutes and no longer than few hundreds of minutes at 1500 -1800°C, type A chondrules terminates their formation by a fast cooling (> 103-104 K/h) in order to preserve their glassy mesostasis. Such inferred thermal history being at odds with nebular shock models, we thus advocate that impacts on planetesimals causing rapid melting and vaporization may provide the high density and highly volatile-enriched gaseous environments required to form chondrules. In this scenario, chondrules and their diversity should result from various degrees of interaction of the ejected fragments with the impact vapor plume; the most oxidizing conditions recorded in type IIA chondrules being very likely the closest to those imposed by the impact vapor plume
Beliefs, media exposure and policy preferences on immigration: Evidence from Europe

International audienceThis article studies the joint determination of beliefs about the economic impact of immigration and immigration policy preferences, using data from the five rounds of the European Social Survey (2002-2010). In addition to standard socio-economic characteristics, this analysis takes individual media consumption into account, as a determinant of opinion about immigration. Our results stress the important role of the endogenous determination of beliefs, which appears as a major determinant of policy preferences. Moreover, media exposure appears as a key determinant of beliefs: individuals who spend more time to get informed on social and political matters through newspapers and radio have a better opinion on the economic impact of immigration compared with individuals who devote time to other types of content
Assessing impact and quality from local dynamics of citation networks

International audienceWe show that essentially local dynamics of citation networks bring special information about the relevance/quality of a paper. Up to some rescaling, they exhibit universal behavior in citation dynamics: temporal patterns are remarkably consistent across disciplines, and uncover a prediction method for citations based on the structure of references only, at publication time. Above-average cited papers universally focus extensively on their own recent subfield - as such, citation counts essentially select what may plausibly be considered as the most disciplinary and normal science; whereas papers which have a peculiar dynamics, such as re-birthing scientific works - 'rediscovered classics' or 'early birds' - are comparatively poorly cited, despite their plausible relevance for the underlying communities. The "rebirth index" that we propose to quantify this phenomenon may be used as a complementary quality-defining criterion, in addition to final citation counts
Modelling the influence of temperature and relative humidity on the time-dependent mechanical behaviour of a short glass fibre reinforced polyamide

WOSInternational audiencePolymer matrix composites, and especially short glass fibre reinforced polyamides, are widely used in the automotive industry. Their application on structural components requires a confident mechanical design taking into account the sensitivity of the mechanical response to both temperature T and relative humidity H. In this paper, the constitutive model already developed by the authors (Launay et al., 2011) is applied to describe the non-linear time-dependent behaviour of a PA66-GF35 under various hygrothermal conditions. The extensive experimental database involves testing conditions under and above the glass transition temperature Tg. An equivalence principle between temperature and relative humidity is applied and validated, since the non-linear mechanical response is shown to depend only on the temperature gap T-Tg(H)
Implicit Digital Surfaces in Arbitrary Dimensions

International audienceIn this paper we introduce a notion of digital implicit surface in arbitrary dimensions. The digital implicit surface is the result of a morphology inspired digitization of an implicit surface { x ∈ R^n : f (x) = 0 } which is the boundary of a given closed subset of R^n , { x ∈ R^n : f (x) ≤ 0 } . Under some constraints, the digital implicit surface has some interesting properties, such as k-tunnel freeness. Furthermore, for a large class of the digital implicit surfaces, there exists a very simple analytical characterization
Reflection-in-Action Markers for Reflection-on-Action in Computer-Supported Collaborative Learning Settings

International audienceWe describe an exploratory study on the use of markers set during a synchronous collaborative interaction (reflection-in-action) for later construction of reflection reports upon the collaboration that occurred (reflection-on-action). During two sessions, pairs of students used the Visu videoconferencing tool for synchronous interaction and marker setting (positive, negative or free) and then individual report building on the interaction (using markers or not). A quantitative descriptive analysis was conducted on the markers put in action, on their use to reflect on action and on the reflection categories of the sentences in these reports. Results show that the students (1) used the markers equally as a note-taking and reflection means during the interaction, (2) used mainly positive markers both to reflect in and on action; (3) paid more attention in identifying what worked in their interaction (conservative direction) rather than in planning on how to improve their group work (progressive direction); (4) used mainly their own markers to reflect on action, with an increase in the use of their partners' markers in the second reflection reports; (5) reflected mainly on their partner in the first reflection reports and more on themselves in the second reports to justify themselves and to express their satisfaction
An evaluation of uncertainties in monitoring middle atmosphere temperatures with the ground-based lidar network in support of space observations

International audienceThe capability of the longest lidar data sets to monitor long-term temperature changes have been evaluated through comparisons with the successive Stratospheric Sounder Units (SSU) onboard NOAA satellites. Cross-consistency investigations between SSU and the lidar network can be considered as a first attempt to demonstrate how the synergistic use of space and ground-based instruments could provide reliable monitoring of the temperature of the middle atmosphere. The breakdown of the temperature cooling trend, and the following flattening observed in the satellite temperature series, are qualitatively confirmed by the lidars. However, there are still large differences that can either be due to SSU continuity (orbit drifts or weighting function modifications) or lidar operation changes (time of measurements, accuracy, sampling, etc.). SSU vertical weighting functions have been taken into account for comparisons. Some discontinuity events cannot be explained by the SSU weighting function drifts due to CO2. For the upper channels of SSU (peaking around 50 km) the results are probably sensitive to the mesospheric part of the lidar profiles that can explain some discontinuities. Tropical lidar stations show clear inter-annual differences with the SSU channels covering the lowest altitude range that need further investigations to understand if the origin is instrumental or geophysical. An attempt to derive non-linear trends with combinations of linear, hockey stick, and quadratic functions has been made. While the quadratic term is not highly significant, this approach allows the derivation of a better quantification of the linear trend terms
Internal waves generated by the wake of Gaussian hills

International audienceDepending on their structure and dynamics, the wakes of various obstacles can generate different kinds of internal waves in stratified fluids. Experiments on waves emitted by three-dimensional Gaussian models towed uniformly in a linearly stratified fluid were carried out. Beyond a critical value Frc of the Froude number Fr, the developed wake was observed to radiate an internal wave field shorter than the lee waves of the hill. The emergence of such waves is correlated with the periodic shedding of three dimensional vortical structures at Fr>Frc. Measurements show that the wavelengths of these short waves are constant in space and time, and proportional to Fr. Their phase and group velocities are proportional to the coherent structure velocity which is estimated from velocity measurements inside the wake. All those spatio-temporal characteristics prove that these short waves are generated by the displacement of the coherent structure inside the wake. © 2001 American Institute of Physics
Measurement of relevant elastic and damping material properties in sandwich thick plates

International audienceAn easy-to-implement method to measure relevant elastic and damping properties of the constituents of a sandwich structure, possibly with a heterogeneous core, is proposed. The method makes use of a one-point dynamical measurement on a thick-plate. The hysteretic model for each (possibly orthotropic) constituent is written generically as "E(1+jη)" for all mechanical parameters. The estimation method of the parameters relies on a mixed experimental/numerical procedure. The frequencies and dampings of the natural modes of the plate are obtained from experimental impulse responses by means of a high-resolution modal analysis technique. This allows for considerably more experimental data to be used. Numerical modes (frequencies, dampings, and modal shapes) are computed by means of an extended Rayleigh-Ritz procedure under the "light damping" hypothesis, for given values of the mechanical parameters. Minimising the differences between the modal characteristics yields an estimation of the values of the mechanical parameters describing the hysteretic behaviour. A sensitivity analysis assesses the reliability of the method for each parameter. Validations of the method are proposed by (a) applying it to virtual plates on which a finite-element model replaces the experimental modal analysis, (b) some comparisons with results obtained by static mechanical measurements, and (c) by comparing the results on different plates made of the same sandwich material