Search

La fonction du manager est circonscrite dès son origine dans l’idée de faire faire aux autres. Ainsi le manager est avant tout celui qui doit « prendre en main », c’est-à-dire à la fois motiver, contrôler et encadrer l’activité des membres de son équipe. Porteurs des modes d’organisations et chargés de leurs mises en œuvre, les managers peuvent se retrouver eux-mêmes victimes de ces modèles et sont souvent les premières victimes des risques psychosociaux. Dans ce contexte n’est-il pas temps d’imaginer un management qui ne surplombe pas le travail mais qui le comprenne réellement et parte du travail réel des différents protagonistes ? Cela est-il possible ? Et comment penser le travail managérial lui-même ? Cette contribution propose une nouvelle conception du management intégrant les analyses formulées par les approches critiques francophones développées par des chercheurs en sciences humaines et sociales, analyses reprises et prolongées par l’ergologie. En effet, la vision du travail portée par l’ergologie induit une vision alternative du management, qui n’impliquerait plus simplement de « faire faire aux autres » mais plutôt de « faire avec les autres » c’est-à-dire coconstruire le sens à donner à son travail, à l’organisation à laquelle on appartient et au vivre-ensemble. Après avoir proposé une brève historique du management au regard des travaux critiques consacrés au management, nous expliciterons en quoi la démarche ergologique permet de fonder une nouvelle approche du management. Puis, nous verrons en quoi cette nouvelle approche consistant à « faire avec » apporterait des éléments de réponse en termes de santé au travail pour les salariés ainsi que pour les managers eux-mêmes, nous proposerons un renouvellement de fonction des managers qui doivent passer du faire faire, à l’ambition de « faire avec ». The manager's function consists in getting others to do things. Thus, the manager is above all the one who must "take charge", i.e. motivate, control and supervise the activity of his team members. As the bearers of organizational modes and responsible for their implementation, managers can find themselves victims of these models and sometimes suffer from psychosocial risks. In this context, isn't it time to imagine a management style that does not overlook work, but that really understands it and starts from the real work of the different protagonists? Is this possible? And how can we think about managerial work itself? This contribution proposes a new conception of management integrating the analyses formulated by the French-speaking critical approaches developed by researchers in the human and social sciences, analyses taken up and extended by ergology. Indeed, the vision of work carried by ergology induces an alternative vision of management, which would no longer imply simply "making others do it" but rather "doing it with others", i.e. co-constructing the meaning to be given to one's work, to the organization to which one belongs and to living together. After having proposed a brief history of management with regard to the critical works devoted to management, we will explain how the ergological approach makes it possible to found a new approach to management. Then, we will see how this new approach consisting in "doing with" would bring elements of response in terms of health at work for the employees as well as for the managers themselves. We will propose a renewal of the function of the managers who must pass from doing to the ambition of "doing with".

Additional file 3: Figure S3. Organisation and position of brain commissures 1 and 2 in E. rowelli. Greyscale light micrographs of selected series of Azan-stained histological sections through the head (from ventral to dorsal). Anterior is up in all images. a–f Pathway of brain commissures 1 (arrowheads) and 2 (arrows). Asterisks indicate anterior parts of four mushroom body lobes. LO, lobes of the mushroom body; OLF, olfactory lobe; PVN, posterior ventral neuropil. Scale bars: 200 μm

Additional file 1: Figure S1. General organisation and position of the brain in E. rowelli. Three-dimensional reconstruction based on SRμCT dataset in anterolateral (a) dorsal (b) and posterior views (c). Dorsal is up in (a and c), anterior is up in (b). A cell body rind (blue) partly covers the neuropils (light-brown). Arrows point to somata-free regions. ANC, antennal nerve cord; CNC, circumpharyngeal nerve cord; DE, deutocerebrum; EY, eye; HO, hypocerebral organ; PR, protocerebrum; SPC, subpharyngeal commissure; VC, ventral commissure; VNC, ventral nerve cord

Additional file 4: Figure S4. Details of olfactory glomeruli and microglomeruli in E. rowelli. Optical sections of confocal micrographs from anti-synapsin immunolabelled vibratome cross sections. a Overview of single glomerulus from olfactory lobe. b Detail from (a) illustrating synapsin-immunoreactive sites. c Overview of single microglomerulus. d Higher magnification of (c) exhibiting synapsin-immunoreactive sites. Note numerous synaptic terminals in both, glomerulus and microglomerulus. (a and c) and (b and d) are to scale. Scale bars: 5 μm (a and c) and 1 μm (b and d)

Additional file 2: Figure S2. Organisation of fascicles of mushroom body in E. rowelli. Horizontal optical sections from CLSM stack of brain. Anterior is up in all images. a DNA staining, b anti-acetylated α-tubulin immunoreactivity, and c merged. Note that fascicles (dotted line) are associated with dense accumulation of small somata (arrowheads) of globuli cells and contains four major, branched fascicles (arrows). ANP, antennal neuropil; CBR, cell body rind; OLF, olfactory lobe; PED, pedunculus. Scale bar: 100 μm

Additional file 5: Figure S5. Organisation and characterisation of brain neuropils in E. rowelli. Three-dimensional reconstruction based on anti-acetylated α-tubulin immunolabelling. Brain in frontal (a and d), anterodorsal (b), and posteroventral views (c) illustrating largely fused neuropils and lobes (bluish grey). a and b For clarity the mushroom bodies, olfactory lobes, frontal neuropil, visual pathways, and central body are collectively shown in semi-transparent light grey. ANC, antennal nerve cord; ANP, antennal neuropil; CNC, circumpharyngeal nerve cord; CN, central neuropil; DN, deutocerebral neuropil; FB, frontal body; FGC, fascicles of globuli cells; JAN, jaw nerve; LIN 2, lip nerve 2; ML, median lobe; OFG, olfactory glomeruli; ONP, optic neuropil; PDN, posterior dorsal neuropil; PHN 1 pharyngeal nerves 1; PVN, posterior ventral neuropil; SAN, subantennal neuropil; SPC, subpharyngeal commissure; SPN, anterior and posterior slime papilla nerves; VC, ventral commissures; VH, ventral horn

Children with unresectable brainstem-infiltrated ganglioglioma have poor progression-free survival when treated with conventional chemotherapy and radiation regimens. The BRAFV600E mutation occurs in a large number of gangliogliomas, making them amenable for targeted therapy using mutation-specific kinase inhibitors. However, limited data exists on the effectiveness and best treatment duration of these inhibitors in this tumor setting. Retrospective description of three cases of childhood brainstem ganglioglioma with BRAFV600E mutation treated in the long-term with Dabrafenib, a specific BRAFV600E kinase inhibitor. Dabrafenib resulted in rapid tumoral regression and significant and durable clinical and radiological improvement. However, all patients had rapid clinical and radiological relapse within days to weeks following treatment discontinuation but showed similar rapid and sustained therapeutic response when Dabrafenib was re-introduced. This targeted therapy has been well tolerated despite its long-term use of 4.8 to 5.5 years in the three patients. Dabrafenib is effective and seemingly safe and well tolerated in our three patients. We observed sustained chemosensitivity even when re-introducing this kinase inhibitor after its discontinuation after 2 years of therapy. These cases indicate the need to re-evaluate the timing and means of Dabrafenib discontinuation in pediatric patients with BRAFV600E mutated gangliogliomas and better assess the future implications of its long-term use.

Martin Christine. Les ArtTechs et Pinakotag. In: Diplômées, n°268-269, 2019. Cultures numériques. pp. 215-225.

This article introduces a new recommendation scenario called coaching. In this scenario, the goal is to help the user modifying his consumption habits lastingly. Each time theuser Uexpresses achoice, thecoach cansuggesta modification in order to guide U towards better habits. We show that the best coaching strategy depends on the user’s characteristics. Six coaching strategies, in which the coach learns the user’s characteristics during interactions, have been compared on an illustrative example., Cet article introduit un nouveau scénario de recommandation : le coaching. Dans ce scénario, l’objectif est de d’aider un utilisateur à modifier durablement ses propres préférences, dans un contexte de choix répétés. À chaque fois que l’utilisateur exprime un choix, le coach peut lui suggérer une modification afin de le guider vers de meilleures habitudes. Nous montrons que la meilleure stratégie du coach dépend des caractéristiques de l’utilisateur. Six stratégies de coaching, dans lesquelles le coach apprend les caractéristiques de l’utilisateur en cours d’interactions ont été comparées.

Pigment-dispersing factor neuropeptides (PDFs) occur in a wide range of protostomes including ecdysozoans (= molting animals) and lophotrochozoans (mollusks, annelids, flatworms, and allies). Studies in insects revealed that PDFs play a role as coupling factors of circadian pacemaker cells, thereby controlling rest-activity rhythms. While the last common ancestor of protostomes most likely possessed only one pdf gene, two pdf homologs, pdf-I and pdf-II, might have been present in the last common ancestors of Ecdysozoa and Panarthropoda (Onychophora + Tardigrada + Arthropoda). One of these homologs, however, was subsequently lost in the tardigrade and arthropod lineages followed by independent duplications of pdf-I in tardigrades and decapod crustaceans. Due to the ancestral set of two pdf genes, the study of PDFs and their receptor (PDFR) in Onychophora might reveal the ancient organization and function of the PDF/PDFR system in panarthropods. Therefore, we deorphanized the PDF receptor and generated specific antibodies to localize the two PDF peptides and their receptor in the onychophoran Euperipatoides rowelli. We further conducted bioluminescence resonance energy transfer (BRET) experiments on cultured human cells (HEK293T) using an Epac-based sensor (Epac-L) to examine cAMP responses in transfected cells and to reveal potential differences in the interaction of PDF-I and PDF-II with PDFR from E. rowelli. These data show that PDF-II has a tenfold higher potency than PDF-I as an activating ligand. Double immunolabeling revealed that both peptides are co-expressed in E. rowelli but their respective levels of expression differ between specific cells: some neurons express the same amount of both peptides, while others exhibit higher levels of either PDF-I or PDF-II. The detection of the onychophoran PDF receptor in cells that additionally express the two PDF peptides suggests autoreception, whereas spatial separation of PDFR- and PDF-expressing cells supports hormonal release of PDF into the hemolymph. This suggests a dual role of PDF peptides—as hormones and as neurotransmitters/neuromodulators—in Onychophora.

The authors present their three years of sheep grazing experiments to open and maintain open landscapes in the chain of the puys of the Volcanoes of Auvergne. The approach integrates notions of botany and animal behaviour allowing, with the shepherd's know-how, good grazing management. Beyond the opening of landscapes, this experience demonstrates the interest of agroforestry - in animal health and welfare.

International audience; Structural and magnetic transitions in the distorted inverse trirutile Mn2TeO6 have been studied between 1.5 and 300 K using magnetization, dielectric permittivity, and specific heat measurements combined with synchrotron x-ray- and neutron-diffraction techniques on polycrystalline samples. A first-order structural transition, strongly hysteretic, occurs progressively over a large temperature span and is characterized by a broad maximum peaking at 53 K in the specific heat data. This structural transition is followed by two antiferromagnetic transitions, to commensurate and incommensurate magnetic orders, at 48 and 26 K, respectively. This succession of structural and magnetic transitions is interpreted as originating from a delicate balance between Jahn-Teller distortion of MnO6 octahedra, rigid TeO6 units, and their consequences on orbital and spin orderings.

Children with unresectable brainstem-infiltrated ganglioglioma have poor progression-free survival when treated with conventional chemotherapy and radiation regimens. The BRAFRetrospective description of three cases of childhood brainstem ganglioglioma with BRAFDabrafenib resulted in rapid tumoral regression and significant and durable clinical and radiological improvement. However, all patients had rapid clinical and radiological relapse within days to weeks following treatment discontinuation but showed similar rapid and sustained therapeutic response when Dabrafenib was re-introduced. This targeted therapy has been well tolerated despite its long-term use of 4.8 to 5.5 years in the three patients.Dabrafenib is effective and seemingly safe and well tolerated in our three patients. We observed sustained chemosensitivity even when re-introducing this kinase inhibitor after its discontinuation after 2 years of therapy. These cases indicate the need to re-evaluate the timing and means of Dabrafenib discontinuation in pediatric patients with BRAF

International audience; The quadruple perovskite calcium manganite (CaMn7O12) is a multiferroic material in which a giant magnetically induced ferroelectric polarization has been reported, making it potentially very interesting for magnetoelectric applications. Here we report the Raman spectroscopy study on this compound of both the phonon modes and the low energy excitations from 4 K to room temperature. A detailed study of the Raman active phonon excitations shows that three phonon modes evidence a spin-phonon coupling at TN2≃50K. In particular, we show that the mode at 432 cm-1 associated with Mn(B)O6 (B position of the perovskite) rotations around the [111] cubic diagonal is impacted by the magnetic transition at 50 K and its coupling to the new modulation of the Mn spin in the (a,b) plane. At low energies, two large low energy excitations are observed at 25 and 47 cm-1. The first one disappears at 50 K and the second one at 90 K. We have associated these excitations to electromagnetoactive modes. © 2019 American Physical Society.

In this work we present the magnetic structures and spin reorientation (SR) transitions of the mixed orthochromite-orthoferrite perovskites RFe0.5Cr0.5O3 (R=Tb, Dy, Ho, Er). Magnetization as a function of temperature and external magnetic field as well as neutron powder diffraction measurements were used to characterize the magnetic transitions, including the SR transitions in the transition metal sublattice and the ordering of the rare earth sublattice. The studied compounds order antiferromagnetically below 270 K in a Gx configuration compatible with the Γ4 representation. As temperature decreases, all the compounds show a SR transition from Gx (Γ4) to Gz (Γ2). This transition occurs in a wide temperature range, where both magnetic configurations coexist. Below this SR, the behavior in each case depends on the rare earth. HoFe0.5Cr0.5O3 shows Ho3+ sublattice ordering at a relatively high temperature (45 K). DyFe0.5Cr0.5O3 and ErFe0.5Cr0.5O3 show a second SR transition of the transition metal sublattice, from Gz (Γ2) to Gy (Γ1) at low temperatures (15 and 8 K, respectively). Below these temperatures a metamagnetic (MM) transition is observed for these two compounds at an external magnetic field of H ≈ 7 kOe. The fact that this is only observed for compounds showing Gz (Γ2) to Gy (Γ1) transition suggests that there is a correlation between the Gy (Γ1) order and the MM transition. Finally, TbFe0.5Cr0.5O3 is a peculiar case, since it is the only compound in this family that shows a re-entrant SR to Gx (Γ4) at very low temperatures. By combining these results with previous reports on RFeO3, RCrO3, and RFe0.5Cr0.5O3, we develop a method to qualitatively estimate the SR temperature and the type of transition. We also propose a complete magnetic phase diagram containing the SR transitions and R3+ ordering temperatures for all the RFe0.5Cr0.5O3 (R=Tb, Dy, Ho, Er, Tm, Yb, and Lu) compounds. Fil: Bolletta, Juan Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentina Fil: Pomiro, Fernando. Universidad Nacional del Litoral; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Física del Litoral. Universidad Nacional del Litoral. Instituto de Física del Litoral; Argentina Fil: Sanchez, Rodolfo Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comision Nacional de Energía Atómica. Gerencia de Área Investigaciones y Aplicaciones no Nucleares. Gerencia de Física (Centro Atómico Bariloche). División Resonancias Magnéticas; Argentina Fil: Pomjakushin, Vladimir. Universidad Nacional de Cuyo; Argentina Fil: Aurelio, Gabriela. Comision Nacional de Energía Atómica. Gerencia de Área Investigaciones y Aplicaciones no Nucleares. Gerencia de Física (Centro Atómico Bariloche). División Física de Metales; Argentina Fil: Maignan, Antoine. Université de Caen Normandie; Francia Fil: Martin, Christine. Université de Caen Normandie; Francia Fil: Carbonio, Raul Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentina

International audience; In this work we present the magnetic structures and spin reorientation (SR) transitions of the mixed orthochromite-orthoferrite perovskites RFe0.5Cr0.5O3 (R = Tb, Dy, Ho, Er). Magnetization as a function of temperature and external magnetic field as well as neutron powder diffraction measurements were used to characterize the magnetic transitions, including the SR transitions in the transition metal sublattice and the ordering of the rare earth sublattice. The studied compounds order antiferromagnetically below 270 K in a G(x) configuration compatible with the Gamma(4) representation. As temperature decreases, all the compounds show a SR transition from G(x) (Gamma(4) ) to G, (Gamma(2)). This transition occurs in a wide temperature range, where both magnetic configurations coexist. Below this SR, the behavior in each case depends on the rare earth. HoFe0.5Cr0.5O3 shows Ho3+ sublattice ordering at a relatively high temperature (45 K). DyFe0.5Cr0.5O3 and ErFe0.5Cr0.5O3 show a second SR transition of the transition metal sublattice, from G(z) (Gamma(2)) to G(y) (Gamma(1)) at low temperatures (15 and 8 K, respectively). Below these temperatures a metamagnetic (MM) transition is observed for these two compounds at an external magnetic field of H approximate to 7 kOe. The fact that this is only observed for compounds showing G(z) (Gamma(2)) to G(y) (Gamma(1)) transition suggests that there is a correlation between the G(y) (Gamma(1)) order and the MM transition. Finally, TbFe0.5Cr0.5O3 is a peculiar case, since it is the only compound in this family that shows a re-entrant SR to G(x) (Gamma(4)) at very low temperatures. By combining these results with previous reports on RFeO3, RCrO3, and RFe0.5Cr0.5O3, we develop a method to qualitatively estimate the SR temperature and the type of transition. We also propose a complete magnetic phase diagram containing the SR transitions and R3+ ordering temperatures for all the RFe0.5Cr0.5O3 (R = Tb, Dy, Ho, Er, Tm, Yb, and Lu) compounds.

International audience; Among the numerous exotic phenomena exhibited by honeycomb antiferromagnets, linear magnetoelectricity in niobiates and tantalates of an A(4)M(2)O(9) formula has been attracting a lot of attention. The magnetic frustration, first exploited in alpha-Cr2O3 in the 1960s, can be tuned in the "429" compounds of which structures derive from corundum, by varying the 3d orbitals filling (from 3d(5) to 3d(7) as A goes from Mn2+ to Co2+) and/or the size of the d(0)M cation (Nb5+ or Ta5+). Fe4Ta2O9 illustrates the physics richness of these compounds, as it exhibits a rare combination of multiferroism and linear magnetoelectricity associated to different magnetic field dependences of the electrical polarization.

International audience; The exchange-bias (EB) effect with sign reversalwas found in LuFe0.5Cr0.5O3 ferrite-chromite, which is a weak ferrimagnet below T-N = 265K, exhibiting antiparallel orientation of the ferromagnetic (FM) moments of the Fe and Cr sublattices due to opposite sign of the Fe-Cr Dzyaloshinskii vector, as compared to that of the Fe-Fe and Cr-Cr. The weak FM moments of the studied compound compensate each other at temperature T-comp = 230 K, leading to the net magnetic moment reversal and to observed negative magnetization, at moderate applied fields, below T-comp. Both vertical and horizontal shifts from the origin were gotten in the field-cooled magnetization hysteresis loops. The EB sign was found to be positive below T-comp and negative above T-comp, with nonmonotonic dependence on cooling field H-cool. It sharply increases at small values of magnetic fields up to H-cool similar to 1 kOe, then remains almost unchanged in the range 1-30 kOe and strongly decreases with further increase of H-cool. This unusual behavior results from the competition of various Dzyaloshinskii-Moriya interactions between Fe3+ and Cr3+ ions.

International audience; The structural, magnetic, and electrical properties of a Fe4Nb2O9 polycrystalline sample have been characterized. It is found that this compound crystallizes in the P (3) over bar c1 space group of the alpha-Al2O3 structure and is thus isostructural to Co4Nb2O9 and Mn4Nb2O9, two linear magnetoelectric oxides. But in marked contrast, its epsilon' (T) curve reveals two broad transitions at T-N1 congruent to 90K and T-N2 congruent to 77K, the former corresponding to the antiferromagnetic ordering temperature. Below T-N1, the M(H) magnetization curves reveal the existence of spin flop at about 6 T. In this temperature region, a H-induced electric polarization for mu H-0 > 6 T is evidenced by both sets of I-p(T)(H) and P(H)(T) curves. All these results point towards Fe4Nb2O9 being a magnetoelectric member of the A(4)B(2)O(9) family (A = Mn, Fe, Co and B = Nb, Ta).

National audience

Background and purposeShorter time-to-thrombolysis in acute ischemic stroke (AIS) is associated with improved functional outcome and reduced morbidity. We evaluate the effect of several interventions to reduce time-to-thrombolysis at an urban, public safety net hospital.MethodsAll patients treated with tissue plasminogen activator for AIS at our institution between 2008 and 2015 were included in a retrospective analysis of door-to-needle (DTN) time and associated factors. Between 2011 and 2014, we implemented 11 distinct interventions to reduce DTN time. Here, we assess the relative impact of each intervention on DTN time.ResultsThe median DTN time pre- and postintervention decreased from 87 (interquartile range: 68-109) minutes to 49 (interquartile range: 39-63) minutes. The reduction was comprised primarily of a decrease in median time from computed tomography scan order to interpretation. The goal DTN time of 60 minutes or less was achieved in 9% (95% confidence interval: 5%-22%) of cases preintervention, compared with 70% (58%-81%) postintervention. Interventions with the greatest impact on DTN time included the implementation of a stroke group paging system, dedicated emergency department stroke pharmacists, and the development of a stroke code supply box.ConclusionsMultidisciplinary, collaborative interventions are associated with a significant and substantial reduction in time-to-thrombolysis. Such targeted interventions are efficient and achievable in resource-limited settings, where they are most needed.

Journal of microscopy 270(3), 343 - 358 (2018). doi:10.1111/jmi.12688, Published by Wiley-Blackwell, Oxford [u.a.]

International audience; The spin dynamics in the distorted triangular lattice antiferromagnet alpha-SrCr2O4 has been investigated by inelastic neutron scattering on a single crystal. The spin wave dispersion has been mapped out in the (0 k l) and (h k 0) planes, and modeled by spin wave calculations, in order to determine the intraplane and interplane exchange couplings. Comparison with alpha-CaCr2O4 shows that, despite the smaller lattice distortion of alpha-SrCr2O4, the deviation from a perfect triangular lattice still affects the spin dynamics of the Sr compound, with a soft mode, similar to the one observed in the Ca counterpart, being observed in (020). Although alpha-SrCr2O4 is further away from a magnetic phase boundary than its Ca counterpart, its dynamic magnetic properties still show intriguing features, which are discussed as quantum fluctuations arising from a two-magnon continuum.

Light micrographs of cross sections, stained with a DNA-selective marker, to visualise differential circumferences of the nerve cord within the interpedal and the leg-bearing regions in Onychophora. (PDF 114 kb)

International audience; The effect of hydrostatic pressure on complex magnetic phase diagram of LuFe2O4 has been investigated by various magnetic measurements in the range of 0-12 kbar. The temperature of the ferrimagnetic (fM) transition (T-N approximate to 245 K) practically does not change with increasing pressure, while the temperature of the appearance of mixed fM and antiferromagnetic (AFM) state at similar to 200 K increases with the rate dT(C)/dP approximate to 0.8 K/kbar. Moreover, an applied pressure suppresses the magnetization, enhances the field of metamagnetic transition, and extends the range of existence of mixed fM and AFM state. Suppression of the ordered magnetic moment under pressure induces a transition from a counterclockwise (CCW) thermal hysteresis below T approximate to 220 K to a clockwise (CW) thermal hysteresis in a magnetic field H = 1 kOe. Nevertheless, field induced metamagnetic transition from mixed fM and AFM state to fM state results in a narrowing of the temperature range of thermal hysteresis and in restoring of CCW type of thermal hysteresis. As a consequence of metamagnetic transition, the thermal hysteresis completed at H = 10 kOe remains one of the CCW type under applied pressure.

International audience; Magnetic and structural properties of CaMn1-xRexO3 (0.02

International audience; Exchange bias effect in CaMn1-xRexO3 (x

International audience; Three members of the perovskite family RFe0.5Cr0.5O3 (R=Lu,Yb, and Tm) have been synthesized and characterized. A systematic study of the crystal and magnetic structures was performed by neutron powder diffraction combined with magnetization measurements. All these compounds crystallize in a Pbnm orthorhombic unit cell and they are already antiferromagnetic at room temperature. The study of the magnetic structure vs temperature showed the occurrence of a progressive spin reorientation from Γ4TM to Γ2TM for the transition metal sublattice, and in the Tm-based sample, a long-range magnetic order of the Tm3+ sublattice was found (Γ8R). These results are in excellent agreement with the magnetic susceptibility measurements. No spin reorientation is observed in the Lu-based sample for which a magnetization reversal at a compensation temperature Tcomp=225K was detected. A clear magnetostrictive effect was observed in the samples with R=Yb and Tm associated with a negative thermal expansion and was assigned to a magnetoelastic effect produced by repulsion between the magnetic moments of neighboring transition metal ions. © 2016 American Physical Society.

Les méthodes d’ensemble ou les méthodes collaboratives supposent que la performance de chaque « expert » soit mesurable (cas de l’apprentissage supervisé) ou soit estimée a priori (cas non supervisé) afin d’attribuer un poids ou une confiance aux informations échangées pour construire la fonction de décision finale. Nous présentons ici une méthode d’apprentissage non supervisé, dans le cas à deux classes inconnues, s’appuyant sur une base d’experts qui sont des boîtes noires dont la performance par rapport aux régularités cibles est inconnue. Nous montrons comment sélectionner automatiquement, dans cette base, des experts performants sur la tâche cible et comment combiner leur résultats pour obtenir une fonction de décision généralement aussi bonne ou meilleure que le meilleur expert (inconnu) de la base. Les expériences réalisées confirment le bon fonctionnement de la méthode.

International audience; Branded for its potential electronic ferroelectricity, charge-ordered LuFe2O4 has a layered Fe triangular framework, whose topology is a source of degeneracy, both at the charge and spin levels. Here we present an in-depth characterization of LuFe2O4-hp, the high-pressure (hp) polymorph of LuFe2O4, using electron, x-ray, and neutron diffraction, combined with transport and magnetization measurements. We show that LuFe2O4-hp is characterized by a misfit-related monoclinic structure, accommodating a buckled triangular [Lu](infinity) layer and two shifted adjacent rectangular [Fe](infinity) planes belonging to a distorted rock salt-type layer. The release of the geometric frustration of the Fe magnetic lattice in the hp form leads to collinear antiferromagnetic ordering at T-N = 380 K. Possible coexistence of charge and magnetic orders in this material opens research pathways for the design of tunable multifunctional devices using high-pressure techniques.

International audience; Random dilution effects in the magnetic zigzag ladder (J1−J2 chain) β−CaCr2−xScxO4 have been investigated combining magnetic susceptibility, specific heat measurements, and neutron scattering. The pseudogapped magnetic excitations observed above TN in β−CaCr2O4 (x=0) persist up to x=0.3 with an increasing characteristic frequency E0 but vanish for x=0.5 for which a quasielastic signal extending up to 8meV becomes the characteristic feature of the magnetic spectrum. Magnetic ordering is seen up to x=0.3 with decreased ordering temperature TN and correlation length. The results are interpreted in terms of the progressive confinement of one-dimensional excitations within shorter chains as x increases and emphasize the crucial role of J2 in propagating magnetic excitations. For an average chain length l smaller than ∼16 magnetic atoms, the system breaks apart into a set of disconnected units with the dynamical properties of a spin glass.

International audience; La présente contribution s’attache aux effets réciproques d’une recherche-action collaborative (RAC) sur le travail des praticiens et sur celui des chercheurs. L’objet de recherche porte sur l’activité de soutien à la parentalité des travailleurs sociaux, analysée à l’aulne de quelques principes :1) centration sur un niveau micro-contextuel des pratiques (la situation, un système familial, des interactions…) qui considère les relations d’influence entre les niveaux de prise en charge par les travailleurs sociaux ;2) mise en liens entre action, développement professionnel et évaluation ;3) co-production de connaissances entre chercheurs, travailleurs sociaux et encadrants des travailleurs sociaux, liée à un développement professionnel ;4) approche compréhensive, à visée non prescriptive, de pratiques d’accompagnement de la parentalité (construction de cadres d’analyse et d’outils pour penser sa pratique).Nous rendons compte ici de la mise en dynamique de ces principes dans la recherche et de ses effets sur les personnes et un collectif de pairs.

Unsupervised one class identification by selecting and combining ranking functions. CAP' 2015 Conférence francophone sur l'Apprentissage Automatique

The biosynthetic gene cluster for the angiogenesis inhibitor borrelidin has been cloned from Streptomyces parvulus Tü4055. Sequence analysis indicates that the macrolide ring of borrelidin is formed by a modular polyketide synthase (PKS) (borA1-A6), a result that was confirmed by disruption of borA3. The borrelidin PKS is striking because only seven rather than the nine modules expected for a nonaketide product are encoded by borA1-A6. The starter unit of the PKS has been verified as trans-cyclopentane-1,2-dicarboxylic acid (trans-1,2-CPDA), and the genes involved in its biosynthesis identified. Other genes responsible for biosynthesis of the nitrile moiety, regulation, and self-resistance were also identified.

Meta-analysis is a powerful tool to perform quantitative syntheses from scientific articles related to some given question such as what is the amount of nitrous oxide coming from fertilizers that ends up as a greenhouse effect agent ? The quality of a meta-analysis is greatly dependent upon the relevance and completeness of the prior bibliographical search. It is common that a first search yields hundreds or thousands of potentially relevant papers. In general, however, only a small number of these articles turn out to be of interest. Their filtering out mobilizes human experts for long periods of time and the process is subject to many and difficult to control defects. This paper describes an automatic process based on machine learning techniques that help to screen the vast amount of literature on a subject., La méta-analyse est un outil puissant pour réaliser des synthèses quantitatives d’articles scientifiques traitant d’un sujet commun, par exemple l’estimation des émissions de gaz à effet de serre. La qualité d’une méta-analyse dépend de plusieurs facteurs, et notamment de la qualité de la recherche bibliographique. Celle-ci génère fréquemment une liste de plusieurs centaines voire plusieurs milliers d’articles. En général, seule une petite partie de ces articles inclut des données exploitables. Dans ce cas, le tri manuel des articles et l’extraction des données constituent des étapes longues (souvent plusieurs mois) et fastidieuses. Ce papier décrit une technique permettant d’automatiser le tri des articles par apprentissage artificiel dans le but de réaliser des méta-analyses portant par exemple sur des problématiques environnementales.

International audience; The presence of electric field–induced polarization reversal behavior just below Néel's antiferromagnetic ordering temperature (TN) is demonstrated in polycrystalline orthorhombic LuCrO3, which crystallizes in the centrosymmetric space group (Pbnm) at room temperature. This result on LuCrO3 is compared with ErCrO3, another orthochromite. The single phase nature and the quality of both polycrystalline samples were checked by x-ray diffraction and transmission electron microscopy (TEM). The high-resolution TEM images of LuCrO3 and ErCrO3 brought out the presence of twin boundaries. Detailed magnetic, dielectric, and polarization studies were carried out on both systems. As the presence of ferroelectric-like characteristics is found below TN in both LuCrO3 and ErCrO3, this rules out the condition for the rare earth cation to be paramagnetic for observing possible signatures of multiferroicity in this family of compounds. Also, we report a much stronger magnetodielectric effect in the case of ErCrO3 compared with LuCrO3 reflecting the different magnetism of their A-site cations.

As one of the closest relatives of arthropods, Onychophora plays an important role in understanding the evolution of arthropod body plans. Currently there is controversy surrounding the evolution of the brain among the ecdysozoan clades, which shows a collar-shaped, circumoral organization in cycloneuralians but a ganglionic architecture in panarthropods. Based on the innervation pattern of lip papillae surrounding the mouth, the onychophoran brain has been interpreted as a circumoral ring, suggesting that this organization is an ancestral feature of Ecdysozoa. However, this interpretation is inconsistent with other published data. To explore the evolutionary origin of the onychophoran mouth and to shed light on the evolution of the ecdysozoan brains, we analyzed the innervation pattern and morphogenesis of the oral lip papillae in the onychophoran Euperipatoides rowelli using DNA labeling, immunocytochemistry, and neuronal tracing techniques. Our morphogenetic data revealed that the seven paired and one unpaired oral lip papillae arise from three anterior-most body segments. Retrograde fills show that only the first and the third nerves supplying the lip papillae are associated with cell bodies within the brain, whereas the second nerve exclusively receives fibers from somata of peripheral neurons located in the lip papillae. According to our anterograde fills and immunocytochemical data, the first nerve supplies the anterior-most pair of lip papillae, whereas the second and the third nerves are associated with the second to fifth and second to eighth lip papillae, respectively. These data suggest that the lip papillae of E. rowelli are mainly innervated by the proto- and deutocerebrum, whereas there are only a few additional cell bodies situated posterior to the brain. According to these findings, the overall innervation pattern of the oral lip papillae in E. rowelli is incompatible with the interpretation of the onychophoran brain as a modified circumoral ring.

The relationship between scientific knowledge and uncertainty in science has been a central question in risk analysis. There have been several conceptualizations of uncertainty but most have been normative efforts to construct an ontology on the basis of theoretical considerations and there have been few empirical attempts to build such an ontology through textual analysis. Studies investigating how such ontologies work are equally scarce. We developed an ontology to investigate uncertainty in risk assessment in food safety comparing the EU and the US, and the two main domains of food safety: biohazards and contaminants. The ontology gauges expressions of uncertainty in two ways: one looks for stylistic clues of judgment, the other registers the content of the uncertainty expressed in the documents. We have built a large data base where English language risk assessment documents by the European Food Safety Agency and the three US agencies primarily responsible for food safety in the US are coded according to our ontology. We are also in the process of creating software that uses machine-learning algorithm to code risk assessment documents in our database. In our paper, we lay out our approach to scientific uncertainty, then describe the ontologies we developed to assess expressions of scientific uncertainty in risk assessment documents in food safety. We then discuss the results from supervised Machine Learning and the implications for both the method of machine coding and the insights we gained for human coding. Finally, we discuss some findings using the ontology testing three sets of hypotheses. The first one looks at differences in national styles in applied scientific research, the second differences in epistemic cultures between scientific subfields in food safety and the third about the effect of research and new knowledge on uncertainty.

A LuFe2O4+delta sample, previously characterized by X-ray synchrotron and neutron diffraction, has been studied by electron microscopy techniques, in order to get a precise description of its micro- and nanostructures at room temperature. The X-ray synchrotron data vs. temperature show that the monoclinic distortion is associated with the charge ordering; this distortion results in elongated twinning domains, which enhance the complexity of the microstructural state at room temperature. The structural modulation associated with oxygen excess is observed in large domains inside a non modulated matrix, in contrast with the modulations associated with the charge ordering of the Fe2+ and Fe3+ species, which are mostly short-range. The investigation of the nature and density of defects in the sample shows that they are nano-scaled, preserving the regularity of the layer stacking mode, and limited to the formation of one- or two-units large stacking faults, associated with gliding mechanisms. Based on these observations, an original description of the LuFe2O4 ferrite structure, through puckered [LuO4](infinity) sandwiching [Fe-2](infinity) layers, is proposed. (C) 2013 Elsevier Masson SAS. All rights reserved.

La connaissance de l’interactome, le réseau complet des interactions protéine-protéine d’un organisme donné, requiert la mise en œuvre de méthodes de détection d’interaction encore peu fiables. Une approche séduisante consiste à combiner les résultats de méthodes différentes afin de diminuer les taux de faux positifs et de faux négatifs. Dans ce papier, nous présentons une méthode originale non paramétrique dans ce but. L’idée fondamentale est de considérer un ensemble de fonctions d’évaluation des données d’apprentissage et de comparer les tris qu’elles produisent. Grâce à une nouvelle mesure de corrélation entre paires de tris, nous pouvons mesurer la différence de corrélation observée sur des échantillons différents. Un processus itératif de construction de nouvelles fonctions d’évaluation à partir des fonctions de base permet progressivement de mettre les données correspondant à ces interactions en tête de classement et ainsi de les identifier.

We have successfully synthesized three quasi-2D geometrically frustrated magnetic compounds (\alpha-MCr_2O_4, M=Ca, Sr, Ba) using the spark-plasma-sintering technique. All these members of the \alpha-MCr_2O_4 family consist of the stacking planar triangular lattices of Cr$^{3+}$ spins (${\rm S}=3/2$), separated by non-magnetic alkaline earth ions. Their corresponding magnetic susceptibility, specific heat, dielectric permittivity and ferroelectric polarization are systematically investigated. A long-range magnetic ordering arises below the N\'{e}el temperature (around 40K) in each member of the \alpha-MCr_2O_4 family, which changes to the quasi-120\degree proper-screw-type helical spin structure at low temperature. A very small but confirmed spontaneous electric polarization emerges concomitantly with this magnetic ordering. The direction of electric polarization is found within the basal triangular plane. The multiferroicity in \alpha-MCr_2O_4 can not be explained within the frameworks of the magnetic exchange striction or the inverse Dzyaloshinskii-Moriya interaction. The observed results are more compatible with the newly proposed Arima mechanism that is associated the d-p hybridization between the ligand and transition metal ions, modified by the spin-orbit coupling. The evolution of multiferroic properties with the increasing inter-planar spacing (as M changes from Ca to Ba) reveals the importance of interlayer interaction in this new family of frustrated magnetic systems., Comment: 10 pages, 8 figures, published online in Physical Review B

International audience; We have successfully synthesized three quasi-two-dimensional geometrically frustrated magnetic compounds (α-MCr2O4, M= Ca, Sr, Ba) using the spark-plasma-sintering technique. All these members of the α-MCr2O4 family consist of the stacking planar triangular lattices of Cr3+ spins (S=3/2), separated by nonmagnetic alkaline-earth ions. Their corresponding magnetic susceptibility, specific heat, dielectric permittivity, and ferroelectric polarization are systematically investigated. A long-range magnetic ordering arises below the Néel temperature (around 40 K) in each member of the α-MCr2O4 family, which changes to the quasi-120∘ proper-screw-type helical spin structure at low temperature. A very small but confirmed spontaneous electric polarization emerges concomitantly with this magnetic ordering. The direction of electric polarization is found within the basal triangular plane. The multiferroicity in α-MCr2O4 can not be explained within the frameworks of the magnetic exchange striction or the inverse Dzyaloshinskii-Moriya interaction. The observed results are more compatible with the newly proposed Arima mechanism that is associated with the d-p hybridization between the ligand and transition-metal ions, modified by the spin-orbit coupling. The evolution of multiferroic properties with the increasing interplanar spacing (as M changes from Ca to Ba) reveals the importance of interlayer interaction in this new family of frustrated magnetic systems.

International audience; Received 4 January 2012; revised 19 March 2012; published 10 July 2012 The magnetic properties of a polycrystalline sample of LuFe2O4 have been investigated by means of magnetization measurements combined with neutron scattering, between 1.5 and 300 K. Magnetic Bragg peaks appear below TN = 240 K and can be indexed in a monoclinic cell, using two propagation vectors, k1 = (0 2/3 0)m and k2 = (0 2/3 1/2)m [or k′2 = (0 2/3 1/6)m], which correspond to either a ferromagnetic or an antiferromagnetic stacking of the [Fe2O4]∞ bilayers. A modeling of possible magnetic structures evidences in addition that the coupling within a bilayer can be either ferromagnetic or antiferromagnetic. Results point out a complex magnetic ground state, which can be understood as coexisting antiferromagnetic and ferrimagnetic phases with a large axial magnetic anisotropy of about 8 meV.

International audience

Molecular simulations allow researchers to obtain complementary data with respect to experimental studies and to overcome some of their limitations. Current experimental techniques do not allow to observe the full dynamics of a protein at atomic detail. In return, experiments provide the structures, i.e. the spatial atomic positions, for numerous biomolecular systems, which are often used as starting point for simulation studies. In order to predict, to explain and to understand experimental results, researchers have developed a variety of biomolecular representations and algorithms. They allow to simulate the dynamic behavior of macromolecules at different scales, ranging from detailed models using quantum mechanics or classical molecular mechanics to more approximate representations. These simulations are often controlled a priori by complex and empirical settings. Most researchers visualise the result of their simulation once the computation is finished. Such post-simulation analysis often makes use of specific molecular user interfaces, by reading and visualising the molecular 3D configuration at each step of the simulation. This approach makes it difficult to interact with a simulation in progress. When a problem occurs, or when the researcher does not achieve to observe the predicted behavior, the simulation must be restarted with other settings or constraints. This can result in the waste of an important number of compute cycles, as some simulations last for a long time: several days to weeks may be required to reproduce a short timespan, a few nanoseconds, of molecular reality. Moreover, several biomolecular processes, like folding or large conformational changes of proteins, occur on even longer timescales that are inaccessible to current simulation techniques. It can thus be necessary to impose empirical constraints in order to accelerate a simulation and to reproduce

International audience; A polycrystalline sample of LuFe2O4 has been investigated by means of powder synchrotron x-ray and neutron diffraction and transmission electron microscopy (TEM), along with Mössbauer spectroscopy and transport and magnetic properties. A monoclinic distortion is unambiguously evidenced, and the crystal structure is refined in the monoclinic C2/m space group [aM = 5.9563(1) Å, bM = 3.4372(1) Å, cM = 8.6431(1) Å, β = 103.24(1)°]. Along with the previously reported modulations distinctive of the charge-ordering (CO) of the iron species, a new type of incommensurate order is observed, characterized by a vector q⃗1 = α1a⃗M* + γ1c⃗M* (with α1 ≅ 0.55, γ1 ≅ 0.13). In situ heating TEM observations from 300 to 773 K confirm that the satellites associated with q⃗1 vanish completely, only at a temperature significantly higher than the CO temperature. This incommensurate modulation has a displacive character and corresponds primarily to a transverse displacive modulation wave of the Lu cations position, as revealed by the high resolution, high angle annular dark field scanning TEM images and in agreement with synchrotron data refinements. Analyses of vacuum-annealed samples converge toward the hypothesis of a new ordering mechanism, associated with a tiny oxygen deviation from the O4 stoichiometry.

L’apprentissage non supervisé a classiquement pour objectif la dé- tection de sous-populations homogènes (classes) sans information a priori sur celles-ci. Les classes sont considérées de manière équivalente. Le problème étudié dans cet article est quelque peu distinct. On s’intéresse uniquement à une sous-population d’intérêt dans l’échantillon étudié que l’on cherche à identifier avec une sensibilité et une spécificité optimales. Nous proposons, pour cela, une méthode s’appuyant sur les principes suivants : (1) travailler dans l’espace de représentation fournis par d’experts faibles pour cette tâche, (2) confronter ces experts pour détecter des seuils de sélection plus pertinents, et (3) les combiner itérativement afin de converger vers l’expert idéal. Cette méthode est éprouvée et comparée sur des données synthétiques.

We have successfully synthesized three quasi-2D geometrically frustrated magnetic compounds (��-MCr_2O_4, M=Ca, Sr, Ba) using the spark-plasma-sintering technique. All these members of the ��-MCr_2O_4 family consist of the stacking planar triangular lattices of Cr$^{3+}$ spins (${\rm S}=3/2$), separated by non-magnetic alkaline earth ions. Their corresponding magnetic susceptibility, specific heat, dielectric permittivity and ferroelectric polarization are systematically investigated. A long-range magnetic ordering arises below the N��el temperature (around 40K) in each member of the ��-MCr_2O_4 family, which changes to the quasi-120\degree proper-screw-type helical spin structure at low temperature. A very small but confirmed spontaneous electric polarization emerges concomitantly with this magnetic ordering. The direction of electric polarization is found within the basal triangular plane. The multiferroicity in ��-MCr_2O_4 can not be explained within the frameworks of the magnetic exchange striction or the inverse Dzyaloshinskii-Moriya interaction. The observed results are more compatible with the newly proposed Arima mechanism that is associated the d-p hybridization between the ligand and transition metal ions, modified by the spin-orbit coupling. The evolution of multiferroic properties with the increasing inter-planar spacing (as M changes from Ca to Ba) reveals the importance of interlayer interaction in this new family of frustrated magnetic systems., 10 pages, 8 figures, published online in Physical Review B