2,941 research outputs found
Interfacial depinning transitions in disordered media: revisiting an old puzzle
Interfaces advancing through random media represent a number of different
problems in physics, biology and other disciplines. Here, we study the
pinning/depinning transition of the prototypical non-equilibrium interfacial
model, i.e. the Kardar-Parisi-Zhang equation, advancing in a disordered medium.
We analyze separately the cases of positive and negative non-linearity
coefficients, which are believed to exhibit qualitatively different behavior:
the positive case shows a continuous transition that can be related to
directed-percolation-depinning while in the negative case there is a
discontinuous transition and faceted interfaces appear. Some studies have
argued from different perspectives that both cases share the same universal
behavior. Here, by using a number of computational and scaling techniques we
shed light on this puzzling situation and conclude that the two cases are
intrinsically different.Comment: 13 pages, 9 figure
ASSET PRICING AND SYSTEMATIC LIQUIDITY RISK: AN EMPIRICAL INVESTIGATION OF THE SPANISH STOCK MARKET
It seems reasonable to expect systematic liquidity shocks to affect the optimal behavior of agents in financial markets. Indeed, fluctuations in various measures of liquidity are significantly correlated across common stocks(Chordia, Roll and Subrahmanyam (2000)). Thus, this paper empirically analyzes whether Spanish expected returns during the nineties are associated cross-sectionally to betas estimated relative to two competing liquidity risk factors. On one hand, we propose a new market-wide liquidity factor which is defined as the difference between returns of stocks highly sensitive to changes in the relative bid-ask spread less returns from stocks with low sensitivities to those changes. We argue that stocks with positive covariability between returns and this factor are assets whose returns tend to go down when aggregate liquidity is low, and hence do not hedge a potential liquidity crisis. Consequently, investors will require a premium to hold these assets. Similarly, note that in the case of assets that covary negatively with the liquidity factor, investors may be willing to pay a premium rather than to require an additional compensation. On the other hand, Pastor and Stambaugh (2002) suggest that a reasonable liquidity risk factor should be associated with the strength of volume-related return reversals since order flow induces greater return reversals when liquidity is lower. Our empirical results show that neither of these proxies for systematic liquidity risk carries a premium in the Spanish stock market.
The (in)visible hand in the Libor market: an Information Theory approach
This paper analyzes several interest rates time series from the United
Kingdom during the period 1999 to 2014. The analysis is carried out using a
pioneering statistical tool in the financial literature: the complexity-entropy
causality plane. This representation is able to classify different stochastic
and chaotic regimes in time series. We use sliding temporal windows to assess
changes in the intrinsic stochastic dynamics of the time series. Anomalous
behavior in the Libor is detected, especially around the time of the last
financial crisis, that could be consistent with data manipulation.Comment: PACS 89.65.Gh Econophysics; 74.40.De noise and chao
Effect of Coulomb interactions on the optical properties of doped graphene
Recent optical conductivity experiments of doped graphene in the infrared
regime reveal a strong background in the energy region between the intra and
interband transitions difficult to explain within conventional pictures. We
propose a phenomenological model taking into account the marginal Fermi liquid
nature of the quasiparticles in graphene near the neutrality point that can
explain qualitatively the observed features. We also study the electronic Raman
signal and suggest that it will also be anomalous.Comment: 4 pages, 2 figure
La Capilla Real de Palacio en la crisis del Antiguo RĂ©gimen: 1808-1820
La entronizaciĂłn en España de JosĂ© Bonaparte, su caĂda tras la derrota del ejĂ©rcito francĂ©s y el regreso de Fernando VII son sucesos que afectarĂĄn a la Capilla Real de Palacio del mismo modo que repercutieron en el resto de las instituciones seglares y eclesiĂĄsticas de la MonarquĂa. En este trabajo se pretende, pues, analizar el impacto de esos acontecimientos en la estructura y el funcionamiento de la Capilla Real, asĂ como en su personal, el cual, obligado por las circunstancias, tuvo forzosamente que tomar partido a su pesar, con las consecuencias que de tal decisiĂłn se derivaban para su futuro profesional.The enthronement of Jose I, his fall after the defeat of french army and the return of Fernando VII, are events that affected to the Royal Chapel of Palace in same way they had effects on the rest of institutions, lay and ecclesiastical, of the Monarchy. This articule tries, therefore, to analize the repercutions of those facts on structure and functions of the Royal Chapel as on its personel, who oblied by circunstancies were forced to take party facing the effects that such a decision would have on their later careers
Experimental and computational study of the effect of temperature on the electro-polymerization process of Thiophene
Temperature effect on the nucleation and growth mechanisms (NGM) of poly(thiophene) (PTh) was investigated through experimental and computational tools. The computational simulation method was based on a kinetic Monte Carlo algorithm. It reproduced key processes such as diffusion, oligomerization, and the precipitation of oligomers onto the electrode surface. Electrochemical synthesis conditions at temperatures between 263 and 303 K were optimized. The deconvolution of the i-t transients reflected two contributions: a progressive nucleation with three-dimensional growth controlled by diffusion and the other by charge transfer, PN3Ddif and PN3Dct, respectively. As temperature decreased, a diminution of the charge associated to each contribution was observed and the nucleation induction time increased. Experimental and computational evidence indicated that temperature does not change the nucleation and growth mechanism (NGM). This effect was ascribed to kinetic factors rather than to film conductivity. This work contrasts simulation and experimental evidence and demonstrates how computational simulations can help to understand the electrochemical process of conducting polymers formation.Fil: Camarada, MarĂa BelĂ©n. Pontificia Universidad CatĂłlica de Chile; Chile. Universidad de Talca; ChileFil: Romero, M.. Pontificia Universidad CatĂłlica de Chile; ChileFil: Gimenez, Maria Cecilia. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - CĂłrdoba. Instituto de FĂsica Enrique Gaviola. Universidad Nacional de CĂłrdoba. Instituto de FĂsica Enrique Gaviola; ArgentinaFil: Schmickler, Wolfgang. Universitat Ulm; AlemaniaFil: del Valle, M. A.. Pontificia Universidad CatĂłlica de Chile; Chil
Interaction driven phases in the honeycomb lattice from exact diagonalization
We investigate the fate of interaction driven phases in the half-filled
honeycomb lattice for finite systems via exact diagonalization with nearest and
next nearest neighbour interactions. We find evidence for a charge density wave
phase, a Kekul\'e bond order and a sublattice charge modulated phase in
agreement with previously reported mean-field phase diagrams. No clear sign of
an interaction driven Chern insulator phase (Haldane phase) is found despite
being predicted by the same mean-field analysis. We characterize these phases
by their ground state degeneracy and by calculating charge order and bond order
correlation functions.Comment: 7 pages, 6 figures, updated reference
Equivalences of ZtĂZ22-cocyclic Hadamard matrices
One of the most promising structural approaches to resolving the
Hadamard Conjecture uses the family of cocyclic matrices over Zt Ă Z2
2.
Two types of equivalence relations for classifying cocyclic matrices over
Zt Ă Z2
2 have been found. Any cocyclic matrix equivalent by either of
these relations to a Hadamard matrix will also be Hadamard.
One type, based on algebraic relations between cocycles over any fi-
nite group, has been known for some time. Recently, and independently,
a second type, based on four geometric relations between diagrammatic
visualisations of cocyclic matrices over Zt Ă Z2
2, has been found. Here
we translate the algebraic equivalences to diagrammatic equivalences and
show one of the diagrammatic equivalences cannot be obtained this way.
This additional equivalence is shown to be the geometric translation of
matrix transposition
Seasonal variation in the diet of Lontra longicaudis in the ParanĂĄ River basin, Argentina
We studied the Neotropical otter ( Lontra longicaudis ) seasonal diet variations in the middle Paran ĂĄ River valley, in central-northern Argentina, at the southern limit of its global range. We recorded 745 prey items in 320 scats collected over the course of 1 year in a tributary stream of the Paran ĂĄ River. Fish, crustaceans, mammals, and insects were the most important items in frequency of occurrence among items. Other items, like mollusks, birds, amphibians, and reptilians were presented in low frequency in all seasons. We recorded seasonal variation in the frequency of the principal categories items: fish, mammals, crustaceans, and insects and in reptilian that had low frequency. Although fish were the most common items consumed by the otter, other groups such as crustaceans, mammals, and insects, were also important in the diet of the Neotropical otter throughout the seasons. Mammals and insects showed a higher frequency in the Neotropical otter diet in our study than in Brazil, Mexico, and even northern Argentina. We noted a marked variation throughout the Neotropical region in the niche breadth indices among studies of Neotropical otter â s diet. The Shannon H âČ diversity index showed a higher value in our study than in most of previous diet analyses of this species.Fil: Vezzosi, RaĂșl Ignacio. Provincia de Entre RĂos. Centro de Investigaciones CientĂficas y Transferencia de TecnologĂa a la ProducciĂłn. Universidad AutĂłnoma de Entre RĂos. Centro de Investigaciones CientĂficas y Transferencia de TecnologĂa a la ProducciĂłn. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Santa Fe. Centro de Investigaciones CientĂficas y Transferencia de TecnologĂa a la ProducciĂłn; ArgentinaFil: Eberhardt, MarĂa Ayelen Teresita. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Santa Fe. Instituto de Ciencias Veterinarias del Litoral. Universidad Nacional del Litoral. Facultad de Cs.veterinarias. Instituto de Ciencias Veterinarias del Litoral; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico - CONICET - Santa Fe. Instituto de Ciencias Veterinarias del Litoral; Argentina. Laboratorio de EcologĂa de Enfermedades; ArgentinaFil: Raimondi, Vanina BelĂ©n. Universidad Nacional de Rosario. Facultad de Ciencias exactas, IngenierĂa y Agrimensura. Museo "Florentino y Carlos Ameghino"; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Santa Fe; ArgentinaFil: Gutierrez, MarĂŹa Florencia. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Santa Fe. Instituto Nacional de LimnologĂa. Universidad Nacional del Litoral. Instituto Nacional de LimnologĂa; ArgentinaFil: Pautasso, AndrĂ©s A.. Universidad Nacional de Rosario. Facultad de Ciencias exactas, IngenierĂa y Agrimensura. Museo "Florentino y Carlos Ameghino"; Argentin
Crespo Solana, Ana, "Mercaderes atlånticos. Redes del comercio flamenco y holandés entre Europa y el Caribe"
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