1,465 research outputs found

    On the determination of the earthquake slip distribution via linear programming techniques

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    The description that one can have of the seismic source is the mani- festation of an imagined model, obviously outlined from Physic Theories and supported by mathematical methods. In that context, the modelling of earthquake rupture consists in finding values of the parameters of the selected physics-mathematical model, through which it becomes possible to reproduce numerically the records of earthquake effects on the Earths surface. We present and test a Linear Programming (LP) inversion in dual form, for reconstructing the kinematics of the rupture of large earthquakes through space-time seismic slip distribution on finite faults planes

    Majorana Fermions Signatures in Macroscopic Quantum Tunneling

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    Thermodynamic measurements of magnetic fluxes and I-V characteristics in SQUIDs offer promising paths to the characterization of topological superconducting phases. We consider the problem of macroscopic quantum tunneling in an rf-SQUID in a topological superconducting phase. We show that the topological order shifts the tunneling rates and quantum levels, both in the parity conserving and fluctuating cases. The latter case is argued to actually enhance the signatures in the slowly fluctuating limit, which is expected to take place in the quantum regime of the circuit. In view of recent advances, we also discuss how our results affect a π\pi-junction loop.Comment: 10 pages, 11 figure

    Extended Seismic Source Characterisation using Linear Programming Inversion in a Dual Formulation

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    A linear programming (LP) inversion method in a dual formulation was applied to reconstruct the kinematics of finite seismic ruptures. In a general setting, this approach can yield results from several data sets: strong ground motion, teleseismic waveforms or/and geodesic data (static deformation). The dual formulation involves the transformation of a normal solution space into an equivalent but reduced space: the dual space. The practical result of this transformation is a simpler inversion problem that is therefore faster to resolve, more stable and more robust. The developed algorithm includes a forward problem that calculates Green’s functions using a finite differences method with a 3D structure model. To evaluate the performance of this algorithm, we applied it to the reconstitution of a realistic slip distribution model from a data set synthesised using this model, i.e., the solution of the forward problem. Several other standard inversion approaches were applied to the same synthetic data for comparison

    Single-Spin Measurement and Decoherence in Magnetic Resonance Force Microscopy

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    We consider a simple version of a cyclic adiabatic inversion (CAI) technique in magnetic resonance force microscopy (MRFM). We study the problem: What component of the spin is measured in the CAI MRFM? We show that the non-destructive detection of the cantilever vibrations provides a measurement of the spin component along the effective magnetic field. This result is based on numerical simulations of the Hamiltonian dynamics (the Schrodinger equation) and the numerical solution of the master equation.Comment: 5 pages + 5 figures (PNG format

    Dynamics of topological defects in a spiral: a scenario for the spin-glass phase of cuprates

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    We propose that the dissipative dynamics of topological defects in a spiral state is responsible for the transport properties in the spin-glass phase of cuprates. Using the collective-coordinate method, we show that topological defects are coupled to a bath of magnetic excitations. By integrating out the bath degrees of freedom, we find that the dynamical properties of the topological defects are dissipative. The calculated damping matrix is related to the in-plane resistivity, which exhibits an anisotropy and linear temperature dependence in agreement with experimental data.Comment: 4 pages, as publishe

    Transient Dynamics in Magnetic Force Microscopy for a Single-Spin Measurement

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    We analyze a single-spin measurement using a transient process in magnetic force microscopy (MFM) which could increase the maximum operating temperature by a factor of Q (the quality factor of the cantilever) in comparison with the static Stern-Gerlach effect. We obtain an exact solution of the master equation, which confirms this result. We also discuss the conditions required to create a macroscopic Schrodinger cat state in the cantilever.Comment: 22 pages 2 figure

    Thrombus aspiration in patients with ST-elevation myocardial infarction: results of a national registry of interventional cardiology.

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    BACKGROUND: We aimed to evaluate the impact of thrombus aspiration (TA) during primary percutaneous coronary intervention (P-PCI) in 'real-world' settings. METHODS: We performed a retrospective study, using data from the National Registry of Interventional Cardiology (RNCI 2006-2012, Portugal) with ST-elevation myocardial infarction (STEMI) patients treated with P-PCI. The primary outcome, in-hospital mortality, was analysed through adjusted odds ratio (aOR) and 95% confidence intervals (95%CI). RESULTS: We assessed data for 9458 STEMI patients that undergone P-PCI (35% treated with TA). The risk of in-hospital mortality with TA (aOR 0.93, 95%CI:0.54-1.60) was not significantly decreased. After matching patients through the propensity score, TA reduced significantly the risk of in-hospital mortality (OR 0.58, 95%CI:0.35-0.98; 3500 patients). CONCLUSIONS: The whole cohort data does not support the routine use of TA in P-PCI, but the results of the propensity-score matched cohort suggests that the use of selective TA may improve the short-term risks of STEMI.info:eu-repo/semantics/publishedVersio

    Phonon-Coupled Electron Tunneling in Two and Three-Dimensional Tunneling Configurations

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    We treat a tunneling electron coupled to acoustical phonons through a realistic electron phonon interaction: deformation potential and piezoelectric, in two or three-dimensional tunneling configurations. Making use of slowness of the phonon system compared to electron tunneling, and using a Green function method for imaginary time, we are able to calculate the change in the transition probability due to the coupling to phonons. It is shown using standard renormalization procedure that, contrary to the one-dimensional case, second order perturbation theory is sufficient in order to treat the deformation potential coupling, which leads to a small correction to the transmission coefficient prefactor. In the case of piezoelectric coupling, which is found to be closely related to the piezoelectric polaron problem, vertex corrections need to be considered. Summing leading logarithmic terms, we show that the piezoelectric coupling leads to a significant change of the transmission coefficient.Comment: 17 pages, 4 figure

    Envelhecimento acelerado de aguardentes vínicas na presença de fragmentos de madeira. Influência nos compostos odorantes

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    A tecnologia de envelhecimento tradicional, que consiste na colocação da aguardente vínica em vasilhas de madeira durante vários anos, é uma técnica morosa e onerosa. Assim, têm vindo a ser introduzidas e desenvolvidas novas técnicas, com o intuito de optimizar o processo e reduzir os custos. Uma dessas novas técnicas consiste em introduzir pedaços de madeira (aparas, toros ou outras formas) na bebida a envelhecer, condicionada em depósitos de inox. Têm sido realizados muitos estudos em vinhos, mas em aguardentes a experimentação é escassa [1, 2]. Assim, este trabalho teve como objectivo avaliar a influência da utilização de alternativas ao envelhecimento de aguardentes em vasilhas de madeira, na composição química das aguardentes obtidas, dando particular atenção aos compostos odorantes provenientes da madeira. Para tal, uma mesma aguardente vínica da Lourinhã foi submetida a um processo de envelhecimento, com três formas de madeira: aguardente colocada em vasilha de madeira (V), aguardente colocada em vasilha de inox com introdução de madeira sob a forma de dominós (D) e aguardente colocada em vasilha de inox com introdução de madeira sob a forma de tábuas (T), tendo sido colhidas amostras de aguardente, ao fim de 180 dias de envelhecimento, para análise e quantificação dos compostos odorantes. Os resultados obtidos mostram que a forma da madeira teve um efeito altamente significativo na maioria dos compostos analisados. No caso dos compostos odorantes derivados da lenhina da madeira (fenois voláteis e vanilina), os teores mais elevados foram encontrados nas aguardentes envelhecidas na presença de fragmentos (dominós ou tábuas), enquanto para os compostos odorantes derivados das hemiceluloses da madeira (ácido acético e aldeídos furânicos) os teores mais elevados foram determinados nas aguardentes envelhecidas em vasilha de madeira. Os resultados deste trabalho sugerem a possibilidade de diferenciação química das aguardentes, em função da tecnologia de envelhecimento

    Fining red wine with plant proteins and yeast extract: effects on the chemical profile and aroma components

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    A colagem dos vinhos usando produtos de origem animal e mineral é uma prática muito comum, contudo as exigências de mercado têm originado novas alternativas a estes produtos, nomeadamente proteínas de origem vegetal e extratos de levedura. O objetivo deste trabalho foi comparar o efeito de três tipos de cola, proteínas de origem vegetal (batata e ervilha), proteínas de origem animal (gelatina) e extrato de leveduras, na composição química e no perfil aromático e sensorial de um vinho tinto. Os produtos de colagem foram aplicados ao vinho na dose mínima e máxima, recomendadas pelo fabricante. Os resultados obtidos mostraram que as proteínas vegetais e o extrato de levedura utilizados não afetaram a composição fenólica dos vinhos. O extrato de levedura foi o mais eficaz relativamente à Rev UIIPS. 2017; 5(2): 78-79. 79 turbidez do vinho. Foram quantificados por GC-MS quatro compostos do aroma dos vinhos designadamente o acetato de isoamilo, o 1-hexanol, o 2-feniletanol e o vanilato de etilo. O extrato de levedura contribuiu para uma maior diminuição no teor em acetato de isoamilo. As proteínas vegetais não afetaram significativamente os teores de 1-hexanol, 2-feniletanol e vanilato de etilo comparativamente com a testemunha. Na análise sensorial, os provadores não detetaram diferenças significativas entre os vinhos tratados com diferentes produtos de colagem.Finning is a frequent practice in oenology, using the gelatins and bentonites. Due to the requirements of the consumers, new products have emerged, as vegetables proteins and yeast extract. The impact of fining products, such as vegetal proteins (potato and peas), yeast extract and gelatin on the chemical and sensory properties of a red wine was investigated. Regarding the phenolic composition, no significant differences were found between the wines treated with different fining products. The turbidity was the lowest in the wine treated with yeast extract. Four wine aroma compounds were quantified by GC-MS: isoamyl acetate, 1-hexane, 2-phenylethanol and ethyl vanilate. The wine treated with yeast extract contained lower concentration of isoamyl acetate. No differences were found among wine samples treated with vegetable proteins for 1-hexanol, 2- phenylethanol and ethyl vanilate. In addition, no significant sensory differences were found among wines treated with different fining products, evaluated by a trained panel.info:eu-repo/semantics/publishedVersio
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