1,465 research outputs found
On the determination of the earthquake slip distribution via linear programming techniques
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
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 -junction loop.Comment: 10 pages, 11 figure
Extended Seismic Source Characterisation using Linear Programming Inversion in a Dual Formulation
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
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
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
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.
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
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 vÃnicas na presença de fragmentos de madeira. Influência nos compostos odorantes
A tecnologia de envelhecimento tradicional, que consiste na colocação da aguardente vÃnica
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 quÃmica das aguardentes
obtidas, dando particular atenção aos compostos odorantes provenientes da madeira.
Para tal, uma mesma aguardente vÃnica 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 aldeÃdos furânicos) os teores mais elevados foram
determinados nas aguardentes envelhecidas em vasilha de madeira.
Os resultados deste trabalho sugerem a possibilidade de diferenciação quÃmica 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
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 proteÃnas de origem vegetal e extratos de levedura.
O objetivo deste trabalho foi comparar o efeito de três tipos de cola, proteÃnas de origem vegetal
(batata e ervilha), proteÃnas de origem animal (gelatina) e extrato de leveduras, na composição
quÃmica e no perfil aromático e sensorial de um vinho tinto. Os produtos de colagem foram aplicados
ao vinho na dose mÃnima e máxima, recomendadas pelo fabricante.
Os resultados obtidos mostraram que as proteÃnas vegetais e o extrato de levedura utilizados não
afetaram a composição fenólica dos vinhos. O extrato de levedura foi o mais eficaz relativamente Ã
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 proteÃnas
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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