3,078 research outputs found
A Random Multifractal Tilling
We develop a multifractal random tilling that fills the square. The
multifractal is formed by an arrangement of rectangular blocks of different
sizes, areas and number of neighbors. The overall feature of the tilling is an
heterogeneous and anisotropic random self-affine object. The multifractal is
constructed by an algorithm that makes successive sections of the square. At
each -step there is a random choice of a parameter related to the
section ratio. For the case of random choice between and we
find analytically the full spectrum of fractal dimensions
La responsabilidad social de la ciencia y tecnología
El impacto mutuo de la Ciencia y Tecnología (CyT) y la sociedad/medio ambiente es el tema tratado genéricamente en este artículo.
Se considerará la definición de la Responsabilidad Social de la Ciencia y Tecnología tomando como referencia el concepto ampliamente
desarrollado en el ámbito empresarial. Además se describirán las connotaciones externas e internas así como sus interrelaciones, lo que proporcionará
al lector una visión genérica de la temáticaThe mutual impact of Science and Technology (S&T) and society/environment is the topic dealt with in this article. The definition
of Social Responsibility of Science y Technology (SR of S&T) can be approached using the concept widely used in modern enterprises. The
internal and external connotations of the SR of S&T will provide to readers a global vision of the topi
Magnetic particles confined in a modulated channel: structural transitions tunable by tilting a magnetic field
The ground state of colloidal magnetic particles in a modulated channel are
investigated as function of the tilt angle of an applied magnetic field. The
particles are confined by a parabolic potential in the transversal direction
while in the axial direction a periodic substrate potential is present. By
using Monte Carlo (MC) simulations, we construct a phase diagram for the
different crystal structures as a function of the magnetic field orientation,
strength of the modulated potential and the commensurability factor of the
system. Interestingly, we found first and second order phase transitions
between different crystal structures, which can be manipulated by the
orientation of the external magnetic field. A re-entrant behavior is found
between two- and four-chain configurations, with continuous second order
transitions. Novel configurations are found consisting of frozen in solitons.
By changing the orientation and/or strength of the magnetic field and/or the
strength and the spatial frequency of the periodic substrate potential, the
system transits through different phases.Comment: Submitted to Phys. Rev. E (10 pages, 12 figures
Genetic and Molecular Factors in Drug-Induced Liver Injury: A Review
The diagnosis of drug-induced liver injury (DILI) is challenging and based on complex diagnostic criteria. DILI falls into two main categories i) intrinsic 'dose-dependent' Type A reactions ii) 'idiosyncratic' or Type B reactions (which are usually not predictable). Idiosyncratic reactions can be immunoallergic (hypersensitivity), or metabolic, although overlap between categories can occur. The aim of this review is to summarise the general view of underlying mechanisms in DILI and to highlight individual risk factors for developing hepatotoxicity. Polymorphisms of bioactivation/ toxification pathways through CYP450 enzymes (Phase I), detoxification reactions (Phase II) and excretion/transport (Phase III) are explored together with immunological factors that might determine DILI. The importance of establishing a multidisciplinary and multi-centric network to promote the understanding and research in hepatotoxicity is underlined. Challenges such as genetic analyses for association studies and whole genome studies, pharmacogenetic testing and future approaches to study DILI are considered. Knowledge regarding these operational mechanisms could provide further insight for the prospective identification of susceptible patients at risk of developing drug-induced hepatotoxicity.
Tunable diffusion of magnetic particles in a quasi-one-dimensional channel
The diffusion of a system of ferromagnetic dipoles confined in a
quasi-one-dimensional parabolic trap is studied using Brownian dynamics
simulations. We show that the dynamics of the system is tunable by an in-plane
external homogeneous magnetic field. For a strong applied magnetic field, we
find that the mobility of the system, the exponent of diffusion and the
crossover time among different diffusion regimes can be tuned by the
orientation of the magnetic field. For weak magnetic fields, the exponent of
diffusion in the subdiffusive regime is independent of the orientation of the
external field.Comment: 9 pages, 13 figures, to appear in Phys. Rev. E (2013
Subcycle squeezing of light from a time flow perspective
Light as a carrier of information and energy plays a fundamental role in both
general relativity and quantum physics, linking these areas that are still not
fully compliant with each other. Its quantum nature and spatio-temporal
structure are exploited in many intriguing applications ranging from novel
spectroscopy methods of complex many-body phenomena to quantum information
processing and subwavelength lithography. Recent access to subcycle quantum
features of electromagnetic radiation promises a new class of time-dependent
quantum states of light. Paralleled with the developments in attosecond
science, these advances motivate an urgent need for a theoretical framework
that treats arbitrary wave packets of quantum light intrinsically in the time
domain. Here, we formulate a consistent time domain theory of the generation
and sampling of few-cycle and subcycle pulsed squeezed states, allowing for a
relativistic interpretation in terms of induced changes in the local flow of
time. Our theory enables the use of such states as a resource for novel
ultrafast applications in quantum optics and quantum information.Comment: 24 pages, 7 figures (including supplementary information
- …