Física de la Matèria Condensada: Recent submissions
Now showing items 361-380 of 1286
Magnetic properties of an Fe/Cu granular multilayer
A Cu/Fe granular film, formed from a multilayer film and composed of particles of Fe imbedded in Cu, has had several of its important properties investigated. Measurements include ferromagentic resonance, magnetoresistance, ...
From caging to rouse dynamics in polymer melts with intramolecular barriers: a critical test of the mode coupling theory
By means of computer simulations and solution of the equations of the mode coupling theory (MCT),we investigate the role of the intramolecular barriers on several dynamic aspects of nonentangled polymers. The investigated ...
Order-parameter fluctuations in Ising spin glasses at low temperatures
We present a numerical study of the order-parameter fluctuations for Ising spin glasses in three and four dimensions at very low temperatures and without an external field. Accurate measurements of two previously introduced ...
Monte Carlo simulations in the unconstrained ensemble
The unconstrained ensemble describes completely open systems whose control parameters are chemical potential, pressure, and temperature. For macroscopic systems with short-range interactions, thermodynamics prevents the ...
What controls the presence and characteristics of aftershocks in rock fracture in the lab?
Aftershock cascades are a characteristic feature of natural seismicity, but underlying mechanisms remain debated. Here, we experimentally explore the presence or absence of aftershocks during failure of intact rock and ...
Antiferromagnetic correlations in Fe-Cu granular alloys: the role of the surface structure
Fe precipitates in a Cufcc matrix, prepared using the Bridgeman method and with an average composition of Cu97Fe3, displayed the coexistence of ferromagnetism ~FM!, spin glass-like ~SGL! behavior and antiferromagnetic ~AFM! ...
Role of adjacency-matrix degeneracy in maximum-entropy-weighted network models
Complex network null models based on entropy maximization are becoming a powerful tool to characterize and analyze data from real systems. However, it is not easy to extract good and unbiased information from these models: ...
Integrabilitat i caos: l'indeterminisme clàssic
Fins l'any 1960 la mecànica clàssica era considerada, per una majoria de físics, com una disciplina tancada de la qual no podien esperar-se nous desenvolupaments i teories. Però a partir del anys seixanta nous resultats ...
Cosmological perturbations in the 5D big bang
Bucher has recently proposed an interesting brane-world cosmological scenario where the ``big bang'' hypersurface is the locus of collision of two vacuum bubbles which nucleate in a five-dimensional flat space. This gives ...
Eyring equation and fluctuation-dissipation far away from equilibrium
Understanding and managing the influence that either external forces or non-equilibrated environments may have on chemical processes is essential for the current and future development of theoretical chemistry. One of the ...
Mean first-passage times for systems driven by equilibrium persistent-periodic dichotomous noise
In a recent paper, [J. M. Porrà, J. Masoliver, and K. Lindenberg, Phys. Rev. E 48, 951 (1993)], we derived the equations for the mean first-passage time for systems driven by the coin-toss square wave, a particular type ...
Normalization factors for magnetic relaxation of small particle systems in non-zero magnetic field.
We critically discuss relaxation experiments in magnetic systems that can be characterized in terms of an energy barrier distribution, showing that proper normalization of the relaxation data is needed whenever curves ...
Observables de partículas relativistas
We study the most general unitary transformation that transform the Hamiltonians of particles of spins 0, 1/2 or 1, into Hamiltonians containing even or odd matrices only. We present also the expressions for the position ...
On likely values of the cosmological constant
We discuss models in which the smallness of the effective vacuum energy density $\rho_\L$ and the coincidence of the time of its dominance $t_\L$ with the epoch of galaxy formation $t_G$ are due to anthropic selection ...
Sistemes socioeconòmics i financers
Els mercats financers, entre molts altres contextos socials i econòmics, amaguen diverses relacions amb la İ sica estadísƟ ca. Sense anar més lluny, el model matemàƟ c de les coƟ tzacions fi nanceres és el mateix uƟ litzat ...
Microwave spectrometry for the Evaluation of the structural integrity of metallic stents
Purpose: To assess the feasibility of a method based on microwave spectrometry to detect structural distortions of metallic stents in open air conditions and envisage the prospects of this approach toward possible medical ...
Light spinless particle coupled to photons
A pseudoscalar or scalar particle $\phi$ that couples to two photons but not to leptons, quarks and nucleons would have effects in most of the experiments searching for axions, since these are based on the $a \gamma \gamma ...
Phenomenological study of the amorphous Fe80B20 ferromagnet with small random anisotropy
The magnetic behavior of some amorphous ferromagnets of composition Fe 80 − x R x B 20 (R being a rare-earth element) is investigated as a function of the external applied magnetic field and temperature using ...
Solutions to the cosmological constant problems
We critically review several recent approaches to solving the two cosmological constant problems. The "old" problem is the discrepancy between the observed value of $\Lambda$ and the large values suggested by particle ...
Prescription for probabilities in eternal inflation
Some of the parameters we call “constants of nature” may in fact be variables related to the local values of some dynamical fields. During inflation, these variables are randomized by quantum fluctuations. In cases when ...
