3,487 research outputs found
A computationally efficacious free-energy functional for studies of inhomogeneous liquid water
We present an accurate equation of state for water based on a simple
microscopic Hamiltonian, with only four parameters that are well-constrained by
bulk experimental data. With one additional parameter for the range of
interaction, this model yields a computationally efficient free-energy
functional for inhomogeneous water which captures short-ranged correlations,
cavitation energies and, with suitable long-range corrections, the non-linear
dielectric response of water, making it an excellent candidate for studies of
mesoscale water and for use in ab initio solvation methods.Comment: 6 pages, 5 figure
Berry phase, topology, and diabolicity in quantum nano-magnets
A topological theory of the diabolical points (degeneracies) of quantum
magnets is presented. Diabolical points are characterized by their diabolicity
index, for which topological sum rules are derived. The paradox of the the
missing diabolical points for Fe8 molecular magnets is clarified. A new method
is also developed to provide a simple interpretation, in terms of destructive
interferences due to the Berry phase, of the complete set of diabolical points
found in biaxial systems such as Fe8.Comment: 4 pages, 3 figure
Os repositórios educacionais como auxiliares do ensino e suas múltiplas linguagens : vídeos
Neste trabalho é feita uma análise de um repositório educacional virtual: o Portal do Professor. Site governamental lançado pelo Ministério da Educação e da Cultura do Brasil (MEC) em parceria com o Ministério da Ciência e Tecnologia. O portal em questão se propõe a auxiliar a prática docente dos professores da Educação Básica (Educação Infantil, Ensino Fundamental e Médio, que no Brasil compreende crianças e jovens geralmente até os 17 anos). O portal oferece algumas ferramentas digitais, como textos digitais, aplicativos computacionais interativos, elementos visuais como fotos e desenhos, elementos auditivos, como sons, e elementos audiovisuais, foco de estudo deste trabalho. A articulação desses fatores, feita pelo próprio professor, pode resultar em aulas sobre determinado tema, que podem ser postadas e acessadas via internet
Spectroscopy on two coupled flux qubits
We have performed spectroscopy measurements on two coupled flux qubits. The
qubits are coupled inductively, which results in a
interaction. By applying microwave radiation, we observe resonances due to
transitions from the ground state to the first two excited states. From the
position of these resonances as a function of the magnetic field applied we
observe the coupling of the qubits. The coupling strength agrees well with
calculations of the mutual inductance
Investor protection through model case procedures – implementing collective goals and individual rights under the 2012 Amendment of the German Capital Markets Model Case Act (KapMuG)
The German Capital Markets Model Case Act (KapMuG) and its amendment of 2012 highlight some fundamentals of collective redress in civil law countries at the example of model case procedures in the field of investor protection. That is why a survey of the ongoing activities of the European Union in the area of collective redress and of its repercussions on the member state level forms a suitable basis for the following analysis of the 2012 amendment of the KapMuG. It clearly brings into focus a shift from sector-specific regulation with an emphasis on the cross-border aspect of protecting consumers towards a “coherent approach” strengthening the enforcement of EU law. As a result, regulatory policy and collective redress are two sides of the same coin today. With respect to the KapMuG such a development brings about some tension between its aim to aggregate small individual claims as efficiently as possible and the dominant role of individual procedural rights in German civil procedure. This conflict can be illustrated by some specific rules of the KapMuG: its scope of application, the three-tier procedure of a model case procedure, the newly introduced notification of claims and the new opt-out settlement under the amended §§ 17-19
Equipment, measurement and dose—a survey for therapeutic ultrasound
Background Dosimetry for Ultrasound Therapy (DUTy) is a large international project which addresses the development of a metrological infrastructure for the determination of ultrasound exposure and dose to tissue. Methods In order to seek the views of the wider therapy ultrasound community and to review dose and in situ exposure quantities that have been suggested or used previously, a web-based questionnaire containing a range of questions covering the type of ultrasound equipment that is used and the range of applications for which it has been developed was created at www.surveymonkey.com. This questionnaire was intended to cover any contemporary therapeutic ultrasound application (including physiotherapy, lithotripsy and drug delivery) and asked specific questions about quantification of in situ exposure and dose, especially as relevant to treatment planning, standardisation and/or regulation. Results This paper summarises the 123 responses submitted between February and September 2014 to the questions on clinical applications, equipment, quality assurance (QA) and measurement and standards, as well as to those relating to an understanding of “dose” in the context of ultrasound. The full set of anonymous responses is available in an additional Excel file. Conclusions The results clearly demonstrate the need not only for further improvements in measuring devices and for measurement guidelines but also for a wider dissemination and higher awareness of existing standards. Whilst it is unlikely that a single definition of dose can be sufficient for all ultrasound treatment modalities, the answers clearly indicate that many aspects would benefit from clear definitions of relevant dose quantities and shed light on the preferred form of such definitions
On the Dirac Structure of the Nucleon Selfenergy in Nuclear Matter
The relativistic structure of the self-energy of a nucleon in nuclear matter
is investigated including the imaginary and real components which arise from
the terms of first and second order in the NN interaction. A parameterized form
of Brueckner matrix is used for the NN interaction. The effects of the
terms beyond the DBHF approximation on quasiparticle energies and the optical
potential for nucleon-nucleus scattering are discussed.Comment: 18 pages, Latex including 10 figures using psfi
Ubiquity of optical activity in planar metamaterial scatterers
Recently it was discovered that periodic lattices of metamaterial scatterers
show optical activity, even if the scatterers or lattice show no 2D or 3D
chirality, if the illumination breaks symmetry. In this Letter we demonstrate
that such `pseudo-chirality' is intrinsic to any single planar metamaterial
scatterer and in fact has a well-defined value at a universal bound. We argue
that in any circuit model, a nonzero electric and magnetic polarizability
derived from a single resonance automatically imply strong bianisotropy, i.e.,
magneto-electric cross polarizability at the universal bound set by energy
conservation. We confirm our claim by extracting polarizability tensors and
cross sections for handed excitation from transmission measurements on
near-infrared split ring arrays, and electrodynamic simulations for diverse
metamaterial scatterers.Comment: 5 pages, 4 figure
Multilinear Wavelets: A Statistical Shape Space for Human Faces
We present a statistical model for D human faces in varying expression,
which decomposes the surface of the face using a wavelet transform, and learns
many localized, decorrelated multilinear models on the resulting coefficients.
Using this model we are able to reconstruct faces from noisy and occluded D
face scans, and facial motion sequences. Accurate reconstruction of face shape
is important for applications such as tele-presence and gaming. The localized
and multi-scale nature of our model allows for recovery of fine-scale detail
while retaining robustness to severe noise and occlusion, and is
computationally efficient and scalable. We validate these properties
experimentally on challenging data in the form of static scans and motion
sequences. We show that in comparison to a global multilinear model, our model
better preserves fine detail and is computationally faster, while in comparison
to a localized PCA model, our model better handles variation in expression, is
faster, and allows us to fix identity parameters for a given subject.Comment: 10 pages, 7 figures; accepted to ECCV 201
Quantum many-body dynamics in a Lagrangian frame: II. Geometric formulation of time-dependent density functional theory
We formulate equations of time-dependent density functional theory (TDDFT) in
the co-moving Lagrangian reference frame. The main advantage of the Lagrangian
description of many-body dynamics is that in the co-moving frame the current
density vanishes, while the density of particles becomes independent of time.
Therefore a co-moving observer will see the picture which is very similar to
that seen in the equilibrium system from the laboratory frame. It is shown that
the most natural set of basic variables in TDDFT includes the Lagrangian
coordinate, , a symmetric deformation tensor , and a
skew-symmetric vorticity tensor, . These three quantities,
respectively, describe the translation, deformation, and the rotation of an
infinitesimal fluid element. Reformulation of TDDFT in terms of new basic
variables resolves the problem of nonlocality and thus allows to regularly
derive a local nonadiabatic approximation for exchange correlation (xc)
potential. Stationarity of the density in the co-moving frame makes the
derivation to a large extent similar to the derivation of the standard static
local density approximation. We present a few explicit examples of nonlinear
nonadiabatic xc functionals in a form convenient for practical applications.Comment: RevTeX4, 18 pages, Corrected final version. The first part of this
work is cond-mat/040835
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