36,211 research outputs found

    On localized vegetation patterns, fairy circles and localized patches in arid landscapes

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    We investigate the formation of localized structures with a varying width in one and two-dimensional systems. The mechanism of stabilization is attributed to strong nonlocal coupling mediated by a Lorentzian type of Kernel. We show that, in addition to stable dips found recently [see, e.g., C. Fernandez-Oto, M. G. Clerc, D. Escaff, and M. Tlidi, Phys. Rev. Lett. {\bf{110}}, 174101 (2013)], exist stable localized peaks which appear as a result of strong nonlocal coupling, i.e. mediated by a coupling that decays with the distance slower than an exponential. We applied this mechanism to arid ecosystems by considering a prototype model of a Nagumo type. In one-dimension, we study the front that connects the stable uniformly vegetated state with the bare one under the effect of strong nonlocal coupling. We show that strong nonlocal coupling stabilizes both---dip and peak---localized structures. We show analytically and numerically that the width of localized dip, which we interpret as fairy circle, increases strongly with the aridity parameter. This prediction is in agreement with filed observations. In addition, we predict that the width of localized patch decreases with the degree of aridity. Numerical results are in close agreement with analytical predictions

    Antigen-induced strain-specific autoantiidiotypic antibodies modulate the immune response to dextran B 512.

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    Sera from CBA and C57BL mice immunized against dextran B 512 eight or more days earlier contain mainly IgG antibodies that specifically suppress the development of plaque-forming cells against dextran in vitro. Suppression was not caused by antibodies against the alpha 1-6 epitope of dextran to any major extent. Sera from CBA mice (IgCH allotype j) suppressed plaque-forming cells from CBA mice, whereas sera from C57BL mice (allotype b) inhibited plaques from C57BL and CBA/Ig-1b mice. Sera from dextran-tolerant mice or from mice that are genetic unresponders to dextran did not suppress plaque-forming cells. Both thymus-independent and thymus-dependent forms of dextran induced the appearance of these autoantiidiotypic antibodies that can distinguish between anti-alpha 1-6 antibodies produced in mouse strains having different IgCH-locus-determined allotypes

    Commissioning of the CMS DT electronics under magnetic field

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    After several months of installation and commissioning of the CMS (Compact Muon Solenoid) DT (Drift Tube) electronics, the system has finally been operated under magnetic field during the so-called CRAFT (Cosmic Run at Four Tesla) exercise. Over 4 weeks, the full detector has been running continuously under magnetic field and managed to acquire more than 300 million cosmic muons. The performance of the trigger and data acquisition systems during this period has been very satisfactory. The main results concerning stability and reliability of the detector are presented and discussed

    The magnetic and crystal structures of Sr2IrO4: A neutron diffraction study

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    We report a single-crystal neutron diffraction study of the layered Sr2IrO4\rm Sr_2IrO_4. This work unambiguously determines the magnetic structure of the system and reveals that the spin orientation rigidly tracks the staggered rotation of the IrO6\rm IrO_6 octahedra in Sr2IrO4\rm Sr_2IrO_4. The long-range antiferromagnetic order has a canted spin configuration with an ordered moment of 0.208(3) ÎŒB\mu_B/Ir site within the basal plane; a detailed examination of the spin canting yields 0.202(3) and 0.049(2) ÎŒB\mu_B/site for the a axis and the b axis, respectively. It is intriguing that forbidden nuclear reflections of space group I41/acdI4_1/acd are also observed in a wide temperature range from 4 K to 600 K, which suggests a reduced crystal structure symmetry. This neutron-scattering work provides a direct, well-refined experimental characterization of the magnetic and crystal structures that are crucial to the understanding of the unconventional magnetism exhibited in this unusual magnetic insulator.Comment: the version appeared in PR

    Virtual libraries of tissue and clinical samples: potential role of a 3-D microscope.

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    Our international innovative teaching group from different European Universities (De Montfort University, DMU, UK; and the Spanish University of AlcalĂĄ, University Miguel HernĂĄndez and University of San Pablo CEU), in conjunction with practicing biomedical scientists in the National Health Service (UK) and biomedical researchers, are developing two complete e-learning packages for teaching and learning medical parasitology, named DMU e-Parasitology (accessible at: http://parasitology.dmu.ac.uk), and biology and chemistry, named DMU e-Biology (accessible at: http://parasitology.dmu.ac.uk/ebiology/index.htm), respectively. Both packages will include a virtual microscope with a complete library of digitised tissue images, clinical slides and cell culture slides/mini-videos for enhancing the teaching and learning of a myriad of techniques applicable to health science undergraduate and postgraduate students. Thus, these packages include detecting human parasites, by becoming familiar with their infective structures and/or organs (e.g. eggs, cysts) and/or explore pathogenic tissues stained with traditional (e.g. haematoxylin & eosin) or more modern (e.g. immunohistochemistry) techniques. The Virtual Microscope (VM) module in the DMU e-Parasitology package is almost completed (accessible at: http://parasitology.dmu.ac.uk/learn/microscope.htm) and contains a section for the three major groups of human-pathogenic parasites (Peña-FernĂĄndez et al., 2018) [1]. Digitised slides are provided with the functionality of a microscope by using the gadget ZoomifyÂź, and we consider that they can enhance learning, as previous studies reported in the literature have reported similar sensitivity and specificity rates for identification of parasites for both digitised and real slides. The DMU e-Biology’s VM, currently in development, will provide healthy and pathological tissue samples from a range of mammalian tissues and organs. This communication will provide a description of both virtual libraries and the process of developing them. In conjunction, we will use a three-dimensional (3D) super-resolution microscopy, 3D Cell Explorer (Nanolive, Lausanne, Switzerland), to incorporate potential 3D microscopic photographs/short videos of cells to provide students with information about the spatial arrangement and morphologies of cells that are essential for life

    Growth and nutritional response of Nemared peach rootstock infected with Pratylenchus vulnus and the mycorrhizal fungus Glomus mosseae

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    Les effets de l'interaction entre #Pratylenchus vulnus et le champignon mycorrhizien #Glomus mosseae sur les porte-greffe de pĂȘcher "Nemared" ont Ă©tĂ© Ă©tudiĂ©s en microparcelles pendant deux saisons de croissance. Le poids frais des pieds, le diamĂštre de la tige, la longueur des pieds et le poids frais des racines sont significativement plus faibles chez les pieds infestĂ©s par le nĂ©matode - qu'ils soient ou non colonisĂ©s par #G. mosseae−quechezlespiedsnoninfesteˊs.Untauxeˊleveˊdephosphoreaugmentelacroissancedespe^chersdanslecasdeteˊmoinsnonmycorrhizeˊs.Lestraitementsdespiedsinfesteˊspar"P.vulnus - que chez les pieds non infestĂ©s. Un taux Ă©levĂ© de phosphore augmente la croissance des pĂȘchers dans le cas de tĂ©moins non mycorrhizĂ©s. Les traitements des pieds infestĂ©s par "P. vulnus Ă  l'aide de mycorrhizes provoquent une diminution de la population finale du nĂ©matode et du nombre de nĂ©matodes par gramme de racine par rapport aux pieds infestĂ©s par #P. vulnus et non traitĂ©s Ă  l'aide du champignon. La colonisation par les mycorrhizes n'est pas affectĂ©e par la prĂ©sence du nĂ©matode. Chez les pieds infestĂ©s par le nĂ©matode, le Cu est le seul Ă©lĂ©ment dĂ©ficitaire dĂ©tectĂ© par analyse foliaire, quoique des taux faibles de fer y aient Ă©tĂ© observĂ©s. Les taux les plus Ă©levĂ©s de Ma, Mg, Mn et Zn ont Ă©tĂ© dĂ©tectĂ©s chez les pieds infestĂ©s par #P. vulnus. Les pieds mycorrhizĂ©s recĂšlent les taux les plus Ă©levĂ©s de Cu et d'Al. #G. mosseae est bĂ©nĂ©fique pour la croissance des pĂȘchers "Nemared" mais ne leur confĂšre aucune protection contre #P. vulnus. (RĂ©sumĂ© d'auteur

    A new class of non-Hermitian Hamiltonians with real spectra

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    We construct a new class of non-Hermitian Hamiltonians with real spectra. The Hamiltonians possess one explicitly known eigenfunction.Comment: 6 page
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