336 research outputs found

    Controlled nucleation of topological defects in the stripe domain patterns of Lateral multilayers with Perpendicular Magnetic Anisotropy: competition between magnetostatic, exchange and misfit interactions

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    Magnetic lateral multilayers have been fabricated on weak perpendicular magnetic anisotropy amorphous Nd-Co films in order to perform a systematic study on the conditions for controlled nucleation of topological defects within their magnetic stripe domain pattern. A lateral thickness modulation of period ww is defined on the nanostructured samples that, in turn, induces a lateral modulation of both magnetic stripe domain periods λ\lambda and average in-plane magnetization component MinplaneM_{inplane}. Depending on lateral multilayer period and in-plane applied field, thin and thick regions switch independently during in-plane magnetization reversal and domain walls are created within the in-plane magnetization configuration coupled to variable angle grain boundaries and disclinations within the magnetic stripe domain patterns. This process is mainly driven by the competition between rotatable anisotropy (that couples the magnetic stripe pattern to in-plane magnetization) and in-plane shape anisotropy induced by the periodic thickness modulation. However, as the structural period ww becomes comparable to magnetic stripe period λ\lambda, the nucleation of topological defects at the interfaces between thin and thick regions is hindered by a size effect and stripe domains in the different thickness regions become strongly coupled.Comment: 10 pages, 7 figures, submitted to Physical Review

    Fracking, Wars and Stock Market Crashes: The Price of Oil During the Great Recession

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    This study analyses how oil prices have been affected by three types of events that took place during the Great Recession: the development of fracking, wars in Libya, Syria and Ukraine and the stock market crash of 2008. To do this, we employ co-integration analysis, using a vector error correction model (VECM) for a period spanning August 2007 to August 2016. The principal results obtained are: firstly, that including a variable to represent the increase in production associated to fracking in the US improves the model's long term estimation, as it embraces a new variable co-integrated in the long term; secondly, that the wars in Libya and Ukraine only influenced prices indirectly, insofar as the former sparked a reduction in OPEC production and the latter an increase in OECD oil reserves, both short term; and thirdly, that the stock market crash of 2008 led to a short- term reduction in oil prices. Keywords: Great Recession, oil prices, fracking, stock market crash, war. JEL Classifications: Q4, Q4

    Fourier-space generalized magneto-optical ellipsometry

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    The magneto-optical Kerr effect (MOKE) is widely exploited in laboratory-based setups for the study of thin films and nanostructures, providing magnetic characterization with good spatial and temporal resolutions. Due to the complex coupling of light with a magnetic sample, conventional MOKE magnetometers normally work by selecting a small range of incident wave-vector values, focusing the incident light beam to a small spot, and recording the reflected intensity at that angular range by means of photodetectors. Using this approach, additional methodologies and measurements are required for full vectorial magnetic characterization. Here, we computationally investigate a Fourier-space MOKE setup, where a focused beam ellipsometer using high numerical aperture optics and a camera detector is employed to simultaneously map the intensity distribution for a wide range of incident and reflected wave vectors. We employ circularly incident polarized light and no analyzing optics, in combination with a fitting procedure of the light intensity maps to the analytical expression of the Kerr effect under linear approximation. In this way, we are able to retrieve the three unknown components of the magnetization vector as well as the material' s optical and magneto-optical constants with high accuracy and short acquisition times, with the possibility of single-shot measurements. Fourier MOKE is thus proposed as a powerful method to perform generalized magneto-optical ellipsometry for a wide range of magnetic materials and devices

    Magnetic properties of permalloy antidot arrayfabricated by interference lithography

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    The interference laser lithography and ion-beam sputtering have been reported. Magneto-optical Kerr effect magnetometry indicated that the sample exhibits four-fold anisotropic behaviour, i.e. different magnetization loops were observed when the external magnetic field was applied along either x-or y-axis, or along the array diagonal. Broadband ferromagnetic resonance measurements revealed a rich variety of different magnetization configurations in the unsaturated state that can be controlled by the orientation of the external magnetic field. Micromagnetic simulations have been performed to explain the observed results. On the contrary, in the saturated regime the system demonstrated almost isotropic magnetic behaviour that improves with external field increase. The obtained results show the potential of interference lithography for the fabrication of large area antidot arrays. (C) 2019 Author(s).The Portuguese team acknowledges the Network of Extreme Conditions Laboratories-NECL and Portuguese Foundation of Science and Technology (FCT) support through the projects NORTE-01-0145-FEDER-022096, MIT-EXPL/IRA/0012/2017, POCI-01-0145-FEDER-031302, EXPL/IF/01191/2013 (D.N.), EXPL/IF/00541/2015 (S.A.B.), EXPL/IF/00981/2013 (G.N.K). D.N., G.N.K., C.R and R.M. acknowledge the support by the European Union Horizon 2020 Research and Innovation Programme under Marie Sklodowska-Curie Grant Agreement EU H2020-MSCA-RISE-2016 (No 734801). The Spanish team acknowledges the support from Spanish MINECO through the grant FIS2016-76058 (AEI/FEDER, UE). A.H.-R. acknowledges the support from European Union's Horizon 2020 research and innovation program under the Marie Sklodowska-Curie Action (reference H2020-MSCA-IF-2016-746958). G.N.K. and O.V.D. acknowledge the support from European Cooperation in Science and Technology (COST) project CA16218 "NANOCOHYBRI.

    Molecular mechanism for the subversion of the retromer coat by the Legionella effector RidL

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    Microbial pathogens employ sophisticated virulence strategies to cause infections in humans. The intracellular pathogen Legionella pneumophila encodes RidL to hijack the host scaffold protein VPS29, a component of retromer and retriever complexes critical for endosomal cargo recycling. Here, we determined the crystal structure of L. pneumophila RidL in complex with the human VPS29?VPS35 retromer subcomplex. A hairpin loop protruding from RidL inserts into a conserved pocket on VPS29 that is also used by cellular ligands, such as Tre-2/Bub2/Cdc16 domain family member 5 (TBC1D5) and VPS9-ankyrin repeat protein for VPS29 binding. Consistent with the idea of molecular mimicry in protein interactions, RidL outcompeted TBC1D5 for binding to VPS29. Furthermore, the interaction of RidL with retromer did not interfere with retromer dimerization but was essential for association of RidL with retromer-coated vacuolar and tubular endosomes. Our work thus provides structural and mechanistic evidence into how RidL is targeted to endosomal membranes.ACKNOWLEDGMENTS: We thank Ander Vidaurrazaga (Centro de Investigación Cooperativa en Biociencias) for technical assistance and Devanand Bondage (National Institute of Child Health and Human Development) for proliferation assays of Legionella pneumophila. This study made use of the Diamond Light Source (Oxfordshire, United Kingdom), the European Synchrotron Radiation Facility (Grenoble, France), and the ALBA synchrotron beamline BL13-XALOC, funded in part by the Horizon 2020 programme of the European Union, iNEXT (H2020 Grant 653706). We thank all the staff from these facilities for technical and human support. This work was supported by the Spanish Ministry of Economy and Competitiveness Grant BFU2014-59759-R (to A.H.); the Severo Ochoa Excellence Accreditation SEV-2016-0644; and the Intramural Program of the Eunice Kennedy Shriver National Institute of Child Health and Human development (Projects ZIA HD001607 and ZIA HD008893). M.R.-M. is supported by a pre-doctoral fellowship from the Basque Government (PRE_2016_2_0249)

    Explorando el potencial bioestimulante del alga invasora Rugulopterix okamurae en vid

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    Trabajo presentado en las IV Jornadas del Grupo de Viticultura de la Sociedad Española de Ciencias Hortícolas, celebradas en Pamplona (España), del 26 al 28 de octubre de 202
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