3,180 research outputs found

    An Evaluation of the Contractionary Devaluation Hypothesis

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    Recent empirical and theoretical literature on the impact of real exchange rate devaluations on economic performance questions the traditional expansionary effect generated within standard Mundell-Fleming models. Contractionary devaluations may arise when firms face maturity or currency mismatches that, when faced with real exchange rate depreciations, lead to balance-sheet effects that erode firms` wealth and lead to an output contraction. While some authors show that the standard Mundell-Fleming result may hold even in the presence of currency mismatches, others point out that, if the balance sheet effect is large enough, devaluations can be contractionary. Using a large panel of 57 countries across the world and various newly constructed measures of dollarization, we test whether the balance sheet effect hypothesis has been relevant during the past decades in explaining economic downturns. Additionally, we explore the channels through which devaluations can be contractionary; in particular, we explore whether investment and consumption decisions are negatively affected by exchange rate devaluations under currency mismatches.

    No classical limit of quantum decay for broad states

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    Though the classical treatment of spontaneous decay leads to an exponential decay law, it is well known that this is an approximation of the quantum mechanical result which is a non-exponential at very small and large times for narrow states. The non exponential nature at large times is however hard to establish from experiments. A method to recover the time evolution of unstable states from a parametrization of the amplitude fitted to data is presented. We apply the method to a realistic example of a very broad state, the sigma meson and reveal that an exponential decay is not a valid approximation at any time for this state. This example derived from experiment, shows the unique nature of broad resonances

    Fracturas de la tibia proximal como complicación de la osteotomía tibial proximal valguizante.

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    Hemos realizado un estudio retrospectivo de 12 osteotomías valguizantes de tibia proximal en las que ocurrió fractura del fragmento proximal, de un total de 409 osteotomías realizadas en nuestro hospital para el tratamiento de la gonartrosis del compartimento medial. La fractura tuvo lugar en la meseta interna en 9 de ellas, en la eminencia intercondílea en 2 y en ambas mesetas tibiales en el caso restante. El mecanismo de producción fue el cierre de la osteotomía en 8 casos, la extensión de la línea de la osteotomía hacia un defecto en el cóndilo afectado en 2 y un fragmento proximal demasiado fino en otros 2. Todas las fracturas consolidaron en 6 semanas. Los resultados de la revisión fueron buenos en 8 y malos en 4 de ellos.We performed a retrospective study of 12 upper closing wedge valgus tibial osteotomies complicated with fracture of the proximal fragment, out of 409, with medial compartment osteoarthritis of the knee. The fracture occured on the medial condyle only in 8 knees, on the medial and lateral condyles in 1 knee and intercondyloid eminence in 2 knees. The mechanism of production were closing of the osteotomy in 8, osteotomy line extended into a defect of the affected condyle in 2, and a thin proximal fragment in 2. All fractures consolidated in six weeks. The clinical results at follow-up were good in 8 and bad in 4

    Superconvergent Perturbation Method in Quantum Mechanics

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    An analogue of Kolmogorov's superconvergent perturbation theory in classical mechanics is constructed for self adjoint operators. It is different from the usual Rayleigh--Schr\"odinger perturbation theory and yields expansions for eigenvalues and eigenvectors in terms of functions of the perturbation parameter.Comment: 11 pages, LaTe

    Stretched-Wire Techniques and Measurements for the Alignment of a 15GHz RF-BPM for CLIC

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    For the Compact LInear Collider (CLIC) project at CERN, maintaining low emittance beams, as they are transported along the two independent 10-20 km long main linacs, is crucial. The beam trajectory therefore has to be very well aligned to the magnetic centre of the quadrupole magnets. A series of microwave cavity beam position monitors (BPM) is foreseen to detect the position of the beam along the main linacs to precisely monitor the beam trajectory in the circular beam pipe of only 8 mm diameter. The PACMAN project aims to demonstrate the pre-alignment of the magnetic field of a main CLIC quadrupole with the electro-magnetic centre of a 15 GHz RF-BPM to the required sub-micron accuracy. This paper focuses on stretched-wire measurements of a CLIC Test Facility (CTF) cavity BPM, to locate its electrical centre. Details of two measurement methods are discussed: RF signal excitation of the wire and analysis of RF signal transfer through the slot-coupled waveguides of the cavity, using the stretched wire as a passive target. This contribution will present the theory behind these measurements, their electromagnetic analysis and first, preliminary experimental results

    A Meiotic Checkpoint Alters Repair Partner Bias to Permit Inter-sister Repair of Persistent DSBs

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    Accurate meiotic chromosome segregation critically depends on the formation of inter-homolog crossovers initiated by double-strand breaks (DSBs). Inaccuracies in this process can drive aneuploidy and developmental defects, but how meiotic cells are protected from unscheduled DNA breaks remains unexplored. Here we define a checkpoint response to persistent meiotic DSBs in C. elegans that phosphorylates the synaptonemal complex (SC) to switch repair partner from the homolog to the sister chromatid. A key target of this response is the core SC component SYP-1, which is phosphorylated in response to ionizing radiation (IR) or unrepaired meiotic DSBs. Failure to phosphorylate (syp-16A) or dephosphorylate (syp-16D) SYP-1 in response to DNA damage results in chromosome non-dysjunction, hyper-sensitivity to IR-induced DSBs, and synthetic lethality with loss of brc-1BRCA1. Since BRC-1 is required for inter-sister repair, these observations reveal that checkpoint-dependent SYP-1 phosphorylation safeguards the germline against persistent meiotic DSBs by channelling repair to the sister chromatid.Cancer Research UK FC0010048UK Medical Research Council FC0010048Wellcome Trust FC0010048Ministerio de Economía y Competitividad BFU2016-75058-PEuropean Research Council ERC2014 AdG669898 TARLOO

    Advanced surface characterization of silver nanocluster segregation in Ag-TiCN bioactive coatings by RBS, GDOES and ARXPS

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    Surface modification by means of wear protective and antibacterial coatings represents, nowadays, a crucial challenge in the biomaterials field in order to enhance the lifetime of bio-devices. It is possible to tailor the properties of the material by using an appropriate combination of high wear resistance (e.g., nitride or carbide coatings) and biocide agents (e.g., noble metals as silver) to fulfill its final application. This behavior is controlled at last by the outmost surface of the coating. Therefore, the analytical characterization of these new materials requires high-resolution analytical techniques able to provide information about surface and depth composition down to the nanometric level. Among these techniques are Rutherford backscattering spectrometry (RBS), glow discharge optical emission spectroscopy (GDOES), and angle resolved X-ray photoelectron spectroscopy (ARXPS). In this work, we present a comparative RBS–GDOES–ARXPS study of the surface characterization of Ag–TiCN coatings with Ag/Ti atomic ratios varying from 0 to 1.49, deposited at room temperature and 200 °C. RBS analysis allowed a precise quantification of the silver content along the coating with a non-uniform Ag depth distribution for the samples with higher Ag content. GDOES surface profiling revealed that the samples with higher Ag content as well as the samples deposited at 200 °C showed an ultrathin (1–10 nm) Ag-rich layer on the coating surface followed by a silver depletion zone (20–30 nm), being the thickness of both layers enhanced with Ag content and deposition temperature. ARXPS analysis confirmed these observations after applying general algorithm involving regularization in addition to singular value decomposition techniques to obtain the concentration depth profiles. Finally, ARXPS measurements were used to provide further information on the surface morphology of the samples obtaining an excellent agreement with SEM observations when a growth model of silver islands with a height d = 1.5 nm and coverage θ = 0.20 was applied to the sample with Ag/Ti = 1.49 and deposited at room temperature.This work was financially supported by the Spanish Ministry of Science and Innovation (projects FUNCOAT CSD2008-00023 and RyC2007-0026). This research is sponsored by FEDER funds through the program COMPETE "Programa Operacional Factores de Competitividade" and by national funds through FCT "Fundacao para a Ciencia e a Tecnologia", in the framework of the Strategic Projects PEST-C/FIS/UI607/2011, and PEST-C/EME/UI0285/2011 and under the project PTDC/CTM/102853/2008. The authors would like to acknowledge I. Caretti and R. Velasco for the fruitful discussions and the proofreading of the manuscript

    Some Remarks on Effective Range Formula in Potential Scattering

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    In this paper, we present different proofs of very recent results on the necessary as well as sufficient conditions on the decrease of the potential at infinity for the validity of effective range formulas in 3-D in low energy potential scattering (Andr\'e Martin, private communication, to appear. See Theorem 1 below). Our proofs are based on compact formulas for the phase-shifts. The sufficiency conditions are well-known since long. But the necessity of the same conditions for potentials keeping a constant sign at large distances are new. All these conditions are established here for dimension 3 and for all angular momenta 0\ell \geq 0

    Ag-Ti(C,N)-based coatings for biomedical applications : influence of silver content on the structural properties

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    Ag–TiCN coatings were deposited by dc reactive magnetron sputtering and their structural and morphological properties were evaluated. Compositional analysis showed the existence of Ag–TiCN coatings with different Ag/Ti atomic ratios (ranging from 0 to 1.49). The structural and morphological properties are well correlated with the evolution of Ag/Ti atomic ratio. For the samples with low Ag/Ti atomic ratio (below 0.20) the coatings crystallize in a B1-NaCl crystal structure typical of TiC0.3N0.7. The increase in Ag/Ti atomic ratio promoted the formation of Ag crystalline phases as well as amorphous CNx phases detected in both x-ray photoelectron spectroscopy and Raman spectroscopy analysis. Simultaneously to the formation of Ag crystalline phases and amorphous carbon-based phases, a decrease in TiC0.3N0.7 grain size was observed as well as the densification of coatings.Spanish Ministry of Science and InnovationFundação para a Ciência e Tecnologia (FCT)CRUP InstitutionMCIN
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