•Magnetism of SmCo/Fe multilayers are studied by an analytical micromagnetic approach.•The effect of interface layer thickness on demagnetization progress is focused on.•Nucleation field and maximum ...energy product go up as interface layer thickness rises.•The existence of an interface layer enhances the exchange coupling interaction.•It is consistent with the experiment in Appl. Phys. Lett. 91, 072509 (2007).
Experiments have found that the interface layer formed by the interface atomic diffusion in the SmCo/Fe hard/soft exchange-spring system may improve magnetic properties such as the nucleation field and energy product. One-dimensional (1D) analytical micromagnetics can well explain the underlying physics of this phenomenon. In this paper, the magnetic properties of SmCo/Fe exchange-spring multilayers are studied by an analytical micromagnetic approach, focusing on the effect of the interface layer thickness on demagnetization progress. The equations for the angular distribution of the magnetization in all layers and the interface constraint are first derived analytically. The microscopic and macroscopic hysteresis loops, the energy product and angular distribution are calculated, with realistic values for the interface layer thickness considered. It is found that as the interface layer thickness increases, the nucleation field rises, the coercivity increases first and then is almost constant, hence the maximum energy product goes up, while the angular distribution and depinning field decrease. The nucleation field rises with the interface layer thickness for a wide region of the interface exchange energy constant, calculated by a three-dimensional (3D) micromagnetic software (OOMMF), which agrees perfectly with 1D calculated results. Meanwhile, the nucleation field goes up with the interface exchange coupling coefficient for any interface layer thickness. Above results indicate that the existence of an interface layer between the soft and hard layers enhances the exchange coupling interaction between them, which is qualitatively consistent with the experiment in Appl. Phys. Lett. 91, 072509 (2007), as confirmed via an in-plane 1D model with interface layer.
We propose a new volatility process in which parameters vary over time according to an artificial neural network (ANN). We prove the process’s stationarity as well as the global identification of the ...parameters. Since ANNs require economic series as input variables, we develop a shrinkage approach to select which explanatory variables are relevant to forecast volatility. Empirically, the proposed model favorably compares with other flexible processes in terms of in-sample fit on six financial returns. It also delivers accurate short-term volatility predictions in terms of root mean squared errors and the predictive likelihood criterion. For long-term forecasts, it can be competitive with the Markov-switching generalized autoregressive conditional heteroskedastic (MS-GARCH) model if appropriate exogenous variables are used. Since our new type of time-varying parameter (TVP) process is based on a universal approximator, the approach can readily revisit and potentially improve many standard TVP applications.
Nitrous oxide (
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) is the main biogenic greenhouse gas contributing to the global warming potential (GWP) of agro-ecosystems. Evaluating the impact of agriculture on climate therefore requires a ...capacity to predict
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emissions in relation to environmental conditions and crop management. Biophysical models simulating the dynamics of carbon and nitrogen in agro-ecosystems have a unique potential to explore these relationships, but are fraught with high uncertainties in their parameters due to their variations over time and space. Here, we used a Bayesian approach to calibrate the parameters of the
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submodel of the agro-ecosystem model CERES-EGC. The submodel simulates
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emissions from the nitrification and denitrification processes, which are modelled as the product of a potential rate with three dimensionless factors related to soil water content, nitrogen content and temperature. These equations involve a total set of 15 parameters, four of which are site-specific and should be measured on site, while the other 11 are considered global, i.e. invariant over time and space. We first gathered prior information on the model parameters based on the literature review, and assigned them uniform probability distributions. A Bayesian method based on the Metropolis–Hastings algorithm was subsequently developed to update the parameter distributions against a database of seven different field-sites in France. Three parallel Markov chains were run to ensure a convergence of the algorithm. This site-specific calibration significantly reduced the spread in parameter distribution, and the uncertainty in the
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simulations. The model’s root mean square error (RMSE) was also abated by 73% across the field sites compared to the prior parameterization. The Bayesian calibration was subsequently applied simultaneously to all data sets, to obtain better global estimates for the parameters initially deemed universal. This made it possible to reduce the RMSE by 33% on average, compared to the uncalibrated model. These global parameter values may be used to obtain more realistic estimates of
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emissions from arable soils at regional or continental scales.
This article studies some bilingual breton-french schoolbooks in their social contexts. Rather than considering the language policies as targeting languages themselves, we first show that the debates ...about languages are often a pretext in conflicts about clericalism. In analysing the schoolbook's paratext, we focus on the way in which both languages, french and breton, are handled in their cohabitation, and which social uses are given to them.
Alcohol Use Disorders (AUD) are among the most prevalent mental disorders in the world. They are the leading risk factor for premature mortality and disability among 15 to 49-year-olds. Links between ...alcohol marketing and patterns of alcohol consumption are well defined in adolescents but there is few data on the impact of alcohol marketing on a population of drinkers with an AUD and seeking treatment. This study was designed in collaboration among researchers specialising in addictive disorders, in social marketing and primary care.
This was a monocentric, cross-sectional, descriptive study. The main objective of this study was to define the type of marketing identified by drinkers with an AUD who were seeking treatment and their beverage preferences. Drinkers aged 18+ with an AUD and seeking treatment were included. A descriptive analysis and a logistic regression were carried out .
N = 91 patients were included, 73.6% were male, the average age was 46.2 years. 72% said they were not influenced by alcohol marketing, but 76% recalled an alcohol advertisement in the last 6 months. The most frequently reported beverage preferences were wine (39.6%), standard beers (29.6%), spirits (27.5%) and strong beers (16.5%).
Patients with AUD, defined as vulnerable, reported exposure to alcohol marketing but did not seem to identify it consciously. Marketing influences differed according to beverage preferences. These results need to be confirmed by a larger study.
is the main causative agent of botulism, a neurological disease encountered in humans as well as animals. Nine types of botulinum neurotoxins (BoNTs) have been described so far. Amongst these ..."toxinotypes," the A, the B and E are the most frequently encountered in humans while the C, D, C/D and D/C are mostly affecting domestic and wild birds as well as cattle. In France for instance, many cases and outbreaks are reported in these animal species every year. However, underestimation is very likely at least for avifauna species where the detection of dead animals can be challenging. Knowledge about BoNTs C, D, C/D, and D/C and the diseases they cause in animals and humans is still scarce and unclear. Specifically, the potential role of animal botulism outbreaks in cattle and poultry as a source of human illness needs to be further assessed. In this narrative review, we present the current knowledge about toxinotypes C, D, C/D, and D/C in cattle and poultry with, amongst various other aspects, their epidemiological cycles. We also discuss the zoonotic potential of these toxinotypes and some possible ways of risk mitigation. An adapted and effective management of botulism outbreaks in livestock also requires a better understanding of these less common and known toxinotypes.
The aim of this proof-of-concept study was to evaluate if trained dogs could discriminate between sweat samples from symptomatic COVID-19 positive individuals (SARS-CoV-2 PCR positive) and those from ...asymptomatic COVID-19 negative individuals. The study was conducted at 2 sites (Paris, France, and Beirut, Lebanon), followed the same training and testing protocols, and involved six detection dogs (three explosive detection dogs, one search and rescue dog, and two colon cancer detection dogs). A total of 177 individuals were recruited for the study (95 symptomatic COVID-19 positive and 82 asymptomatic COVID-19 negative individuals) from five hospitals, and one underarm sweat sample per individual was collected. The dog training sessions lasted between one and three weeks. Once trained, the dog had to mark the COVID-19 positive sample randomly placed behind one of three or four olfactory cones (the other cones contained at least one COVID-19 negative sample and between zero and two mocks). During the testing session, a COVID-19 positive sample could be used up to a maximum of three times for one dog. The dog and its handler were both blinded to the COVID-positive sample location. The success rate per dog (i.e., the number of correct indications divided by the number of trials) ranged from 76% to 100%. The lower bound of the 95% confidence interval of the estimated success rate was most of the time higher than the success rate obtained by chance after removing the number of mocks from calculations. These results provide some evidence that detection dogs may be able to discriminate between sweat samples from symptomatic COVID-19 individuals and those from asymptomatic COVID-19 negative individuals. However, due to the limitations of this proof-of-concept study (including using some COVID-19 samples more than once and potential confounding biases), these results must be confirmed in validation studies.
Despite their unquestionable properties, oligonucleotide aptamers display some drawbacks that continue to hinder their applications. Several strategies have been undertaken to overcome these ...weaknesses, using thrombin binding aptamers as proof-of-concept. In particular, the functionalization of a thrombin exosite I binding aptamer (TBA) with aromatic moieties, e.g., naphthalene dimides (N) and dialkoxynaphthalenes (D), attached at the 5′ and 3′ ends, respectively, proved to be highly promising. To obtain a molecular view of the effects of these modifications on aptamers, we performed a crystallographic analysis of one of these engineered oligonucleotides (TBA-NNp/DDp) in complex with thrombin. Surprisingly, three of the four examined crystallographic structures are ternary complexes in which thrombin binds a TBA-NNp/DDp molecule at exosite II as well as at exosite I, highlighting the ability of this aptamer, differently from unmodified TBA, to also recognize a localized region of exosite II. This novel ability is strictly related to the solvophobic behavior of the terminal modifications. Studies were also performed in solution to examine the properties of TBA-NNp/DDp in a crystal-free environment. The present results throw new light on the importance of appendages inducing a pseudo-cyclic charge-transfer structure in nucleic acid-based ligands to improve the interactions with proteins, thus considerably widening their potentialities.
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End-functionalization with phosphodiester-linked donor-acceptor groups provides novel properties to TBA aptamer. In particular, a comprehensive crystallographic analysis reveals for the first time a secondary low-affinity binding site of a TBA-like aptamer on thrombin exosite II. The presence of the appendages could finely modulate the hydrophobicity of other G-quadruplex-based aptamers.
Pseudomonas aeruginosa (PA) and Burkholderia ambifaria (BA) are two opportunistic Gram negative bacteria and major infectious agents involved in lung infection of cystic fibrosis patients. Both ...bacteria can develop resistance to conventional antibiotherapies. An alternative strategy consists of targeting virulence factors in particular lectins with high affinity ligands such as multivalent glycoclusters. LecA (PA-IL) and LecB (PA-IIL) are two tetravalent lectins from PA that recognise galactose and fucose respectively. BambL lectin from BA is trimeric with 2 binding sites per monomer and is also specific for fucose. These three lectins are potential therapeutic targets in an anti-adhesive anti-bacterial approach. Herein, we report the synthesis of 18 oligonucleotide pentofuranose-centered or mannitol-centered glycoclusters leading to tri-, penta- or decavalent clusters with different topologies. The linker arm length between the core and the carbohydrate epitope was also varied leading to 9 galactoclusters targeting LecA and 9 fucoclusters targeting both LecB and BambL. Their dissociation constants (Kd) were determined using a DNA-based carbohydrate microarray technology. The trivalent xylo-centered galactocluster and the ribo-centered fucocluster exhibited the best affinity for LecA and LecB respectively while the mannitol-centered decafucocluster displayed the best affinity to BambL. These data demonstrated that the topology and nature of linkers were the predominant factors for achieving high affinity rather than valency.
Well-defined optically pure transition metal (TM) complexes bearing C 1- and C 2-symmetric N-heterocyclic carbene (NHC) ligands were prepared from prochiral NHC precursors. As predicted by DFT ...calculations, our strategy capitalizes on the formation of a metal-carbene bond which induces an axis of chirality. Configurationally stable atropisomers of various NHC-containing TM complexes were isolated by preparative HPLC on a chiral stationary phase in good yields and excellent optical purities (up to 99.5% ee). The carbene transfer from an optically pure Cu complex to a gold or palladium center reveals, for the first time, a full stereoretentivity, supporting the hypothesis of an associative mechanism for the transmetalation. The potential of these new chiral TM complexes was illustrated in asymmetric catalysis with up to 98% ee.
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