pinecone/core-2020-05-10-deduplication huggingface dataset:
Estimating hyperparameters and instrument parameters in regularized inversion. Illustration for SPIRE/Herschel map making.

International audienceWe describe regularized methods for image reconstruction and focus on the question of hyperparameter and instrument parameter estimation, i.e. unsupervised and myopic problems. We developed a Bayesian framework that is based on the \post density for all unknown quantities, given the observations. This density is explored by a Markov Chain Monte-Carlo sampling technique based on a Gibbs loop and including a Metropolis-Hastings step. The numerical evaluation relies on the SPIRE instrument of the Herschel observatory. Using simulated and real observations, we show that the hyperparameters and instrument parameters are correctly estimated, which opens up many perspectives for imaging in astrophysics
Electron transfer at the mineral/water interface: Selenium reduction by ferrous iron sorbed on clay

International audienceThe mobility and availability of the toxic metalloid selenium in the environment is largely controlled by sorption and redox reactions, which may proceed at temporal scales similar to that of subsurface water movement under saturated or unsaturated conditions. Since such waters are often anaerobic and rich in Fe2+, we investigated the long-term (≤ 1 month) kinetics of selenite (Se(IV)O3 -) sorption to montmorillonite in the presence of Fe2+ under anoxic conditions. A synthetic montmorillonite was used to eliminate the influence of structural Fe. In the absence of aqueous Fe2+, selenite was sorbed as outer-sphere sorption complex, covering only part of the positive edge sites, as verified by a structure-based MUSIC model and Se K-edge XAS (X-ray absorption spectroscopy). When selenite was added to montmorillonite previously equilibrated with Fe2+ solution however, slow reduction of Se and formation of a solid phase was observed with Se K-edge XANES (x-ray absorption near-edge spectroscopy) and EXAFS (extended x-ray absorption finestructure) spectroscopy. Iterative transformation factor analysis of XANES and EXAFS spectra suggested that only one Se reaction product formed, which was identified as nano-particulate Se(0). Even after one month, only 75% of the initially sorbed Se(IV) was reduced to this solid species. Mössbauer spectrometry revealed that before and after addition and reduction of Se, 5% of total sorbed Fe occurred as Fe(III) species on edge sites of montmorillonite (≈ 2 mmol kg-1). The only change observed after addition of Se was the formation of a new Fe(II) species (15%) attributed to the formation of an outer-sphere Fe(II)-Se sorption complex. The combined Mössbauer and XAS results hence clearly suggest that the Se and Fe redox reactions are not directly coupled. Based on the results of a companion paper, we hypothesize that the electrons produced in the absence of Se by oxidation of sorbed Fe(II) are stored, for example by formation of surface H2 species, and are then 3 available for the later Se(IV) reduction. The slow reaction rate indicates a diffusion controlled process. Homogeneous precipitation of an iron selenite was thermodynamically predicted and experimentally observed only in the absence of clay. Interestingly, half of Fe was oxidized in this precipitate (Mössbauer). Since DFT calculations predicted the oxidation of Fe at the water-FeSe solid interface only and not in the bulk phase, the average particle size of this precipitate does not exceed 2 nm. A comparison with the Mössbauer and XAS spectra of the clay samples demonstrates that such homogenous precipitation can be excluded as a mechanism for the observed slow Se reduction, emphasizing the role of abiotic, heterogeneous precipitation and reduction for the removal of Se from subsurface waters
Signatures of solar event at middle and low latitudes in the Europe-African sector, during geomagnetic storms, October 2013

International audienceThis paper presents the variability of the total electron content, VTEC, the ROTI index (proxy of the scintillation index) and the transient variations of the Earth's magnetic field associated to the impacts of solar events during October 2013. The observations are from middle and low latitudes in European African longitude sector. During October 2013, there are four solar events reaching the Earth. The two first events, on October 2 and October 8 are CME, the third event on October 14, is a jet of fast solar wind flowing from a solar coronal hole, and the last event on October 30 is a slow solar wind with southward excursions of the Bz component of the Interplanetary magnetic field, associated to CME passing near the Earth. For the four events, the variation of VTEC at middle latitudes is the same and presents an increase of VTEC at the time of the impact followed by a decrease of VTEC, lasting one or several days. At low latitudes, no clear common pattern for all the events appears. For the four events the variation of the ROTI index over Africa is different showing the asymmetry between West and East Africa. For the first event, on October 2, the scintillations are not inhibited, for the second and the fourth events on October 8 and 30, the scintillations are inhibited on East Africa and for the third event (high speed solar wind stream), on October 14, the scintillations are inhibited over the whole Africa. The available data allow the full explanation of the observations of October 14, indeed, on this day, there is no post sunset increase of the virtual height h'F2 at Ascension Island. There is no Pre Reversal Enhancement (PRE) of the eastward electric field; it is this electric field which moves up the F layer, the necessary condition for the existence of scintillation. The analysis of the variations of the Earth's magnetic field at low latitudes highlights the presence of the ionospheric disturbance dynamo on October 14, which produces a decrease of the Equatorial Electrojet, several hours after the impact of the high speed solar wind. The disturbance dynamo electric field (DDEF) is westward during the day and till after sunset and turns eastward around 22.30LT. So, on October 14, the westward DDEF inhibits the eastward regular electric field
Equivalent Theories of Liquid Crystal Dynamics

International audienceThere are two competing descriptions of nematic liquid crystal dynamics: the Ericksen-Leslie director theory and the Eringen micropolar approach. Up to this day, these two descriptions have remained distinct in spite of several attempts to show that the micropolar theory includes the director theory. In this paper we show that this is the case by using symmetry reduction techniques and introducing a new system that is equivalent to the Ericksen-Leslie equations and may include disclination dynamics. The resulting equations of motion are verified to be completely equivalent, although one of the two different reductions offers the possibility of accounting for orientational defects. After applying these two approaches to the ordered micropolar theory of Lhuiller and Rey, all the results are eventually extended to flowing complex fluids, such as nematic liquid crystals. © 2013 Springer-Verlag Berlin Heidelberg
Equivalent Absorption Capacity (EAC) concept applied to the absorption of hydrophobic VOCs in a water/PDMS mixture

International audienceAbsorption of hydrophobic Volatile Organic Compounds (VOCs) in multiphase system gas water PolyDiMethylSiloxane (PDMS, i.e. silicone oils) was considered. Absorption experiments were carried out in a countercurrent gas-liquid absorber filled with Raschig rings as packing. Three absorbing liquids, water, PDMS and a mixture of water/PDMS (90/10 v/v) were used to transfer toluene and dimethyl disulfide (DMDS) selected as VOC targets. Moreover, the Equivalent Absorption Capacity (EAC) concept previously developed to characterize the mixtures of water/PDMS was applied to the experimental data obtained at three different gas flow rates (18, 25 and 32 m3 h-1). Experimental measurements showed that absorption efficiencies (E) were low for water (around 2-8% for toluene and around 12-25% for DMDS) and higher for PDMS (from 88% to 98% according to the operating conditions). For the water/PDMS mixture, it was shown that the PDMS addition increased significantly the absorption of pollutants (E values in the range 25 to 65% according to the operating conditions). Besides, it was emphasized that the EAC concept describes satisfactorily the absorption behavior of the water/PDMS mixture. Finally, results confirmed that pure PDMS has to be used rather than a (90/10 v/v) water/PDMS mixture for hydrophobic VOC absorption. Using pure PDMS as absorbing liquid (dynamic viscosity of 5 mPa s), high absorption efficiencies (up to 98%) were obtained for L’/G’ value around 5 (L’/G’ corresponding to the ratio between the specific flow of the liquid and the specific flow of the gas). Under such conditions, pressure drops (ΔP) in the packed column and overall mass transfer coefficients (KLa) were around 1000 Pa m-1 (G’ = 1.06 kg m-2 h-1) and 5 10-3 s-1, respectively
The Non-overlapping Constraint between Objects Described by Non-linear Inequalities

International audiencePacking 2D objects in a limited space is an ubiquitous problem with many academic and industrial variants. In any case, solving this problem requires the ability to determine where a first object can be placed so that it does not intersect a second, previously placed, object. This subproblem is called the non-overlapping constraint. The complexity of this non-overlapping constraint depends on the type of objects considered. It is simple in the case of rectangles. It has also been studied in the case of polygons. This paper proposes a numerical approach for the wide class of objects described by non-linear inequalities. Our goal here is to calculate the non-overlapping constraint, that is, to describe the set of all positions and orientations that can be assigned to the first object so that intersection with the second one is empty. This is done using a dedicated branch & prune approach. We first show that the non-overlapping constraint can be cast into a Minkowski sum, even if we take into account orientation. We derive from this an inner contractor, that is, an operator that removes from the current domain a subset of positions and orientations that necessarily violate the non-overlapping constraint. This inner contractor is then embedded in a sweeping loop, a pruning technique that was only used with discrete domains so far. We finally come up with a branch & prune algorithm that outperforms Rsolver, a generic state-of-the-art solver for continuous quantified constraints
Copper and tin isotopic analysis of ancient bronzes
for archaeological investigation: development and validation
of a suitable analytical methodology

Although in many cases Pb isotopic analysis can be relied on for provenance determination of ancient bronzes, sometimes the use of “non-traditional” isotopic systems, such as those of Cu and Sn, is required. The work reported on in this paper aimed at revising the methodology for Cu and Sn isotope ratio measurements in archaeological bronzes via optimization of the analytical procedures in terms of sample pre-treatment, measurement protocol, precision, and analytical uncertainty. For Cu isotopic analysis, both Zn and Ni were investigated for their merit as internal standard (IS) relied on for mass bias correction. The use of Ni as IS seems to be the most robust approach as Ni is less prone to contamination, has a lower abundance in bronzes and an ionization potential similar to that of Cu, and provides slightly better reproducibility values when applied to NIST SRM 976 Cu isotopic reference material. The possibility of carrying out direct isotopic analysis without prior Cu isolation (with AG-MP-1 anion exchange resin) was investigated by analysis of CRM IARM 91D bronze reference material, synthetic solutions, and archaeological bronzes. Both procedures (Cu isolation/no Cu isolation) provide similar δ 65Cu results with similar uncertainty budgets in all cases (±0.02–0.04 per mil in delta units, k = 2, n = 4). Direct isotopic analysis of Cu therefore seems feasible, without evidence of spectral interference or matrix-induced effect on the extent of mass bias. For Sn, a separation protocol relying on TRU-Spec anion exchange resin was optimized, providing a recovery close to 100 % without on-column fractionation. Cu was recovered quantitatively together with the bronze matrix with this isolation protocol. Isotopic analysis of this Cu fraction provides δ 65Cu results similar to those obtained upon isolation using AG-MP-1 resin. This means that Cu and Sn isotopic analysis of bronze alloys can therefore be carried out after a single chromatographic separation using TRU-Spec resin. Tin isotopic analysis was performed relying on Sb as an internal standard used for mass bias correction. The reproducibility over a period of 1 month (n = 42) for the mass bias-corrected Sn isotope ratios is in the range of 0.06–0.16 per mil (2 s), for all the ratios monitored
Effect of pressure on single-chain magnets with repeating units of the MnIII-NiII-MnIII trimer

The single-chain magnet (SCM) system [Mn2(saltmen)2Ni(pao)2(L)2](A)2 (L: intrachain attaching ligand of NiII ion; A?1: interchain counteranion) is a ferromagnetic one-dimensional network system with repeating units of the MnIII-NiII-MnIII trimer which itself behaves as a single-molecule magnet with an S=3 spin ground state and negative uniaxial single-ion anisotropy (D) parallel to the bridging direction. The slow relaxation of the magnetic moment in this SCM system originates in an energy barrier for spin reversal (E), which is closely related to the ferromagnetic interaction between the trimers (Jtrimer) as well as to the D of the trimer. We have investigated the effects of pressure on three compounds representative of the above SCM family through ac susceptibility measurements under hydrostatic pressures up to P=13.5  kbar and crystal structural analysis experiments up to P=20.0  kbar, and have observed a pronounced enlargement of E when J was artificially increased. The application of hydrostatic pressure brought about the systematic enhancement of E (a maximum increase of 10% within the pressure region of the experiments). The pressure dependence of E varied according to the kind of attaching ligand L involved and the intrachain structure, and we have experimentally found that isotropic lattice shrinkage is desirable if a continuous increase of E in this system is aimed at
Exponential energy growth due to slow parameter oscillations in quantum mechanical systems

It is shown that a periodic emergence and destruction of an additional quantum number leads to an exponential growth of energy of a quantum mechanical system subjected to a slow periodic variation of parameters. The main example is given by systems (e.g., quantum billiards and quantum graphs) with periodically divided configuration space. In special cases, the process can also lead to a long period of cooling that precedes the acceleration, and to the desertion of the states with a particular value of the quantum number
Does rapid HIV disease progression prior to combination antiretroviral therapy hinder optimal CD4 + T-cell recovery once HIV-1 suppression is achieved?

Objective: This article compares trends in CD4+ T-cell recovery and proportions achieving optimal restoration (>=500 cells/µl) after viral suppression following combination antiretroviral therapy (cART) initiation between rapid and nonrapid progressors. Methods: We included HIV-1 seroconverters achieving viral suppression within 6 months of cART. Rapid progressors were individuals experiencing at least one CD4+ less than 200 cells/µl within 12 months of seroconverters before cART. We used piecewise linear mixed models and logistic regression for optimal restoration. Results: Of 4024 individuals, 294 (7.3%) were classified as rapid progressors. At the same CD4+ T-cell count at cART start (baseline), rapid progressors experienced faster CD4+ T-cell increases than nonrapid progressors in first month [difference (95% confidence interval) in mean increase/month (square root scale): 1.82 (1.61; 2.04)], which reversed to slightly slower increases in months 1–18 [-0.05 (-0.06; -0.03)] and no significant differences in 18–60 months [-0.003 (-0.01; 0.01)]. Percentage achieving optimal restoration was significantly lower for rapid progressors than nonrapid progressors at months 12 (29.2 vs. 62.5%) and 36 (47.1 vs. 72.4%) but not at month 60 (70.4 vs. 71.8%). These differences disappeared after adjusting for baseline CD4+ T-cell count: odds ratio (95% confidence interval) 0.86 (0.61; 1.20), 0.90 (0.38; 2.17) and 1.56 (0.55; 4.46) at months 12, 36 and 60, respectively. Conclusion: Among people on suppressive antiretroviral therapy, rapid progressors experience faster initial increases of CD4+ T-cell counts than nonrapid progressors, but are less likely to achieve optimal restoration during the first 36 months after cART, mainly because of lower CD4+ T-cell counts at cART initiation
Functional Asynchronous Networks: Factorization of Dynamics and Function

In this note we describe the theory of functional asynchronous networks and one of the main results, the Modularization of Dynamics Theorem, which for a large class of functional asynchronous networks gives a factorization of dynamics in terms of constituent subnetworks. For these networks we can give a complete description of the network function in terms of the function of the events comprising the network and thereby answer a question originally raised by Alon in the context of biological networks
Electro-optical characterization of IC compatible microcantilevers

The aim of this work is to simulate and optically characterize the piezoelectric performance of complementary metal oxide semiconductor (CMOS) compatible microcantilevers based on aluminium nitride (AlN) and manufactured at room temperature. This study should facilitate the integration of piezoelectric micro-electro-mechanical systems (MEMS) such as microcantilevers, in CMOS technology. Besides compatibility with standard integrated circuit manufacturing procedures, low temperature processing also translates into higher throughput and, as a consequence, lower manufacturing costs. Thus, the use of the piezoelectric properties of AlN manufactured by reactive sputtering at room temperature is an important step towards the integration of this type of devices within future CMOS technology standards. To assess the reliability of our fabrication process, we have manufactured arrays of free-standing microcantilever beams of variable dimension and studied their piezoelectric performance. The characterization of the first out-of-plane modes of AlN-actuated piezoelectric microcantilevers has been carried out using two optical techniques: laser Doppler vibrometry (LDV) and white light interferometry (WLI). In order to actuate the cantilevers, a periodic chirp signal in certain frequency ranges was applied between the device electrodes. The nature of the different vibration modes detected has been studied and compared with that obtained by a finite element model based simulation (COMSOL Multiphysics), showing flexural as well as torsional modes. The correspondence between theoretical and experimental data is reasonably good, probing the viability of this high throughput and CMOS compatible fabrication process. To complete the study, X-ray diffraction as well as d33 piezoelectric coefficient measurements were also carried out
Rapid adaptation to microgravity in mammalian macrophage cells

Despite the observed severe effects of microgravity on mammalian cells, many astronauts have completed long term stays in space without suffering from severe health problems. This raises questions about the cellular capacity for adaptation to a new gravitational environment. The International Space Station (ISS) experiment TRIPLE LUX A, performed in the BIOLAB laboratory of the ISS COLUMBUS module, allowed for the first time the direct measurement of a cellular function in real time and on orbit. We measured the oxidative burst reaction in mammalian macrophages (NR8383 rat alveolar macrophages) exposed to a centrifuge regime of internal 0 g and 1 g controls and step-wise increase or decrease of the gravitational force in four independent experiments. Surprisingly, we found that these macrophages adapted to microgravity in an ultra-fast manner within seconds, after an immediate inhibitory effect on the oxidative burst reaction. For the first time, we provided direct evidence of cellular sensitivity to gravity, through real-time on orbit measurements and by using an experimental system, in which all factors except gravity were constant. The surprisingly ultra-fast adaptation to microgravity indicates that mammalian macrophages are equipped with a highly efficient adaptation potential to a low gravity environment. This opens new avenues for the exploration of adaptation of mammalian cells to gravitational changes
Research to optimise human performance

The need for greater understanding of the factors which limit human movement and functional capacity and for determining effective methods for ensuring optimum performance has led to a wide range of related research studies. This paper draws on some of the research projects pursued or supervised by the author, to show the knowledge gained in aspects of movement capacity, muscle function and the influence of sensory motor deficits on movement and function. The inter-relationship of the many factors influencing functional capacity emphasise the need to think broadly in research. Studies of effectiveness of physiotherapy and collection of data for ergonomic workplace design highlight the importance of both prevention and therapeutic care and demonstrate the contributions which physiotherapists can make through research to optimise human performance
Lithography-based addtive manufacture of ceramic biodevices with design-controlled surface topographies

The possibility of manufacturing textured materials\ud
and devices, with surface properties controlled from the design stage, instead of being the result of machining processes or chemical attacks, is a key factor for the incorporation of advanced functionalities to a wide set of micro- and nanosystems. High-precision additive manufacturing (AM) technologies based on photopolymerization, together with the use of fractal models linked to computer-aided design tools, allow for a precise definition of final surface properties.\ud
However, the polymeric master parts obtained with most commercial systems are usually inadequate for biomedical\ud
purposes and their limited strength and size prevents many\ud
potential applications. On the other hand, additive\ud
manufacturing technologies aimed at the production of final\ud
parts, normally based on layer-by-layer melting or sintering\ud
ceramic or metallic powders, do not always provide the required precision for obtaining controlled micro-structured surfaces with high-aspect-ratio details. Towards the desired degree of precision and performance, lithography-based ceramic manufacture is a remarkable option, as we discuss in the present study, which presents the development of two different micro-textured biodevices for cell culture. Results show a remarkable control of the surface topography of ceramic parts and the possibility of obtaining design-controlled micro-structured surfaces with high-aspect-ratio micro-metric details