323 research outputs found

    THE INFLUENCE OF OROGRAPHY DURING DEEP MEDITERRANEAN CYCLOGENESIS 11-15 NOVEMBER 2004

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    The deep cyclogenesis causing a range of severe weather events took place over the Mediterranean Sea from 11- 15 November 2004. The first phase of the event was analysed by a series of numerical experiments using the MM5 forecast model. Factor separation method was applied to investigate the cyclogenetic and cyclolytic influences of orography, upper-level potential vorticity and latent heat flux from the sea as well as their mutual synergies in the cyclone initiation and movement in the lee of Atlas Mountains. Results of model simulations show that pure orographic effect is responsible for generation of the low-level shallow vortex in the lee, while upper-level PV anomaly is a dominant effect in the later stage of lee formation. In addition, upperlevel PV anomaly is crucial for advection of the system to the Mediterranean Sea, where the cyclone experienced a severe deeping in the mature stage of its development

    Analysis of the environments of seven Mediterranean tropical-like storms using an axisymmetric, nonhydrostatic, cloud resolving model

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    Tropical-like storms on the Mediterranean Sea are occasionally observed on satellite images, often with a clear eye surrounded by an axysimmetric cloud structure. These storms sometimes attain hurricane intensity and can severely affect coastal lands. A deep, cut-off, cold-core low is usually observed at mid-upper tropospheric levels in association with the development of these tropical-like systems. In this study we attempt to apply some tools previously used in studies of tropical hurricanes to characterise the environments in which seven known Mediterranean events developed. In particular, an axisymmetric, nonhydrostatic, cloud resolving model is applied to simulate the tropical-like storm genesis and evolution. Results are compared to surface observations when landfall occurred and with satellite microwave derived wind speed measurements over the sea. Finally, sensitivities of the numerical simulations to different factors (e.g. sea surface temperature, vertical humidity profile and size of the initial precursor of the storm) are examined

    Mechanisms of institutional continuity in neoliberal "success stories" : developmental regimes in Chile and Estonia

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    © 2015 by The American Society for Biochemistry and Molecular Biology, Inc. Several mycoplasmas, such as the emergent human pathogen Mycoplasma genitalium, developed a complex polar structure, known as the terminal organelle (TO), responsible for a new type of cellular motility, which is involved in a variety of cell functions: cell division, adherence to host cells, and virulence. The TO cytoskeleton is organized as a multisubunit dynamic motor, including three main ultrastructures: the terminal button, the electrodense core, and the wheel complex. Here, we describe the interaction between MG200 and MG491, two of the main components of the TO wheel complex that connects the TO with the cell body and the cell membrane. The interaction between MG200 and MG491 has a KD in the 80 nM range, as determined by surface plasmon resonance. The interface between the two partners was confined to the >enriched in aromatic and glycine residues> (EAGR) box of MG200, previously described as a protein-protein interaction domain, and to a 25-residue-long peptide from the C-terminal region of MG491 by surface plasmon resonance and NMR spectroscopy studies. An atomic description of the MG200 EAGR box binding surface was also provided by solution NMR. An M. genitalium mutant lacking the MG491 segment corresponding to the peptide reveals specific alterations in cell motility and cell morphology indicating that the MG200-MG491 interaction plays a key role in the stability and functioning of the TO.This work was supported by Ministerio de Ciencia e Innovacion Grants BFU2012-36827 (to I. F.) and BFU2010-22209-C02-01 (to E. Q.), a grant from the Centre de Referencia de R+D de Biotecnologia (Generalitat de Catalunya, Spain) (to E. Q.), and by FEDER funds through the Operational Competitiveness Programme-COMPETE and by Portuguese national funds through FCT-Fundação para a CiĂȘncia e a Tecnologia under Project FCOMP-01-0124-FEDER-027581 (EXPL/BBB-BQB/0546/2012) (to B. C.). The NMR characterization was conducted through the FP7 Access to Research Infrastructures (Bio-NMR Contract 261863) and by Instruct, which is part of the European Strategy Forum on Research Infrastructures (ESFRI) and supported by national member subscriptionsPeer Reviewe

    Spectroscopic and microscopic investigations of tautomerization in porphycenes: condensed phases, supersonic jets, and single molecule studies

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    We describe various experimental approaches that have been used to obtain a detailed understanding of double hydrogen transfer in porphycene, a model system for intramolecular hydrogen bonding and tautomerism. The emerging picture is that of a multidimensional tautomerization coordinate, with several vibrational modes acting as reaction-promoters or inhibitors through anharmonic intermode coupling. Tunnelling processes, coherent in the case of isolated molecules and incoherent in condensed phases, are found to play a major role even at elevated temperatures. Single-molecule spectroscopy studies reveal large fluctuations in hydrogen transfer rates observed over time for the same chromophore. Scanning probe microscopy is employed to directly observe the structure and tautomerization dynamics of single molecules adsorbed on metal surfaces and demonstrates how the interactions of the molecules with atoms of the supporting surface affect their static and dynamic properties: different tautomeric forms are stabilized for molecules depending on the surface structure and the reaction mechanism can also change, from a concerted to a stepwise transfer. The scanning probe microscopy studies prove that tautomerization in single molecules can be induced by different stimuli: heat, electron attachment, light, and force exerted by the microscope’s tip. Possible applications utilizing tautomerism are discussed in combination with molecular architectures on surfaces, which could pave the way for the development of single-molecule electronics

    Conformations in crystals and solutions of d(CACGTG), d(CCGCGG) and d(GGCGCC) studied by vibrational spectroscopy

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    Crystals of self camplementary DMA hexamers dCCACGTG>, dCCCGCGG> and d were grown bf vapour dlffuslon technlque and studled by mlcroRaman and mlcroiR spectroscop es. The ollgonucleotldes were studled ln parallel ln solutlon by vlbratlonal spectroscopy. A B->Z transltlon was detected by Raman spectroscopy cl.lrlng the crystalllzatlon procese for dCCACGTG>. Vlbratlonal spectroscopy shows that the dCGGCGCC> crystals adopt a B geametry. On the contrary the d sequence whlch ls shown to be able to undergo ln solutlon or ln fllms qulte easlly the B->Z transltlon, remalns trapped ln crystals ln a geametry whlch may correspond to an lntermedlate conformatlon often proposed ln modele of the B->Z transltlon. The crystals used ln thls study were characterlzed by X-ray dlffractlon. The unlt cell and space group have been determlned

    Electrical switching of a chiral lasing from polariton condensate in a Rashba-Dresselhaus regime

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    Efficient optical classical and quantum information processing imposes on light novel requirements: chirality with low threshold non-linearities. In this work we demonstrate a chiral lasing from an optical modes due to emerging photonic Rashba-Dresselhaus spin-orbit coupling (SOC). For this purpose we developed a new electrically tunable device based on an optical cavity filled with birefringent liquid crystal (LC) and perovskite crystals. Our novel method for the growth of single crystals of CsPbBr3_3 inorganic perovskite in polymer templates allows us to reach a strong light-matter coupling regime between perovskite excitons and cavity modes, and induce polariton condensation. The sensitivity of the LC to external electric fields lets us to tune the condensate energy in situ and induce synthetic SOC. This shapes the condensate between a single linearly polarized or two circularly polarized separated in momentum, emitting coherent light. The difference in the condensation thresholds between the two SOC regimes can be used to switch on and off the chiral condensate emission with a voltage.Comment: 8 pages, 5 figure

    Attraction between DNA molecules mediated by multivalent ions

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    The effective force between two parallel DNA molecules is calculated as a function of their mutual separation for different valencies of counter- and salt ions and different salt concentrations. Computer simulations of the primitive model are used and the shape of the DNA molecules is accurately modelled using different geometrical shapes. We find that multivalent ions induce a significant attraction between the DNA molecules whose strength can be tuned by the averaged valency of the ions. The physical origin of the attraction is traced back either to electrostatics or to entropic contributions. For multivalent counter- and monovalent salt ions, we find a salt-induced stabilization effect: the force is first attractive but gets repulsive for increasing salt concentration. Furthermore, we show that the multivalent-ion-induced attraction does not necessarily correlate with DNA overcharging.Comment: 51 pages and 13 figure

    Real-time investigation of dynamic protein crystallization in living cells

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    X-ray crystallography requires sufficiently large crystals to obtain structural insights at atomic resolution, routinely obtained in vitro by time-consuming screening. Recently, successful data collection was reported from protein microcrystals grown within living cells using highly brilliant free-electron laser and third-generation synchrotron radiation. Here, we analyzed in vivo crystal growth of firefly luciferase and Green Fluorescent Protein-tagged reovirus ÎŒNS by live-cell imaging, showing that dimensions of living cells did not limit crystal size. The crystallization process is highly dynamic and occurs in different cellular compartments. In vivo protein crystallization offers exciting new possibilities for proteins that do not form crystals in vitroL.R., M.K., D.R., and C.B. thank the German Federal Ministry for Education and Research (BMBF) for funding (Grant Nos. 01KX0806 and 01KX0807). L.R., M.D., and C.B. acknowledge support from the BMBF in the context of the Röntgen-Angström-Cluster (Grant No. 05K12GU3). J.M.-C. and A.B.-N. acknowledge support from the Spanish Ministerio EconomĂ­a y Competitividad (MINECO, Grant No. BFU2013-43513-R). I.V.M., R.D., and L.R. are grateful for support from the DFG Cluster of Excellence “Inflammation at Interfaces” (EXC 306)S
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