2,846 research outputs found
Effects of the Zero-Mode Landau Level on Inter-Layer Magnetoresistance in Multilayer Massless Dirac Fermion Systems
We report on the experimental results of interlayer magnetoresistance in
multilayer massless Dirac fermion system -(BEDT-TTF)I under
hydrostatic pressure and its interpretation. We succeeded in detecting the
zero-mode Landau level (n=0 Landau level) that is epected to appear at the
contact points of Dirac cones in the magnetic field normal to the
two-dimensional plane. The characteristic feature of zero-mode Landau carriers
including the Zeeman effect is clearly seen in the interlayer
magnetoresistance.Comment: 2 pages, 2 figure
improving performance of feature extraction in sfm algorithms for 3d sparse point cloud
Abstract. The use of Structure-from-Motion algorithms is a common practice to obtain a rapid photogrammetric reconstruction. However, the performance of these algorithms is limited by the fact that in some conditions the resulting point clouds present low density. This is the case when processing materials from historical archives, such as photographs and videos, which generates only sparse point clouds due to the lack of necessary information in the photogrammetric reconstruction. This paper explores ways to improve the performance of open source SfM algorithms in order to guarantee the presence of strategic feature points in the resulting point cloud, even if sparse. To reach this objective, a photogrammetric workflow is proposed to process historical images. The first part of the workflow presents a method that allows the manual selection of feature points during the photogrammetric process. The second part evaluates the metric quality of the reconstruction on the basis of a comparison with a point cloud that has a different density from the sparse point cloud. The workflow was applied to two different case studies. Transformations of wall paintings of the Karanlık church in Cappadocia were analysed thanks to the comparison of 3D model resulting from archive photographs and a recent survey. Then a comparison was performed between the state of the Komise building in Japan, before and after restoration. The findings show that the method applied allows the metric scale and evaluation of the model also in bad condition and when only low-density point clouds are available. Moreover, this tool should be of great use for both art and architecture historians and geomatics experts, to study the evolution of Cultural Heritage
Electric-field-induced lifting of the valley degeneracy in alpha-(BEDT-TTF)_2I_3 Dirac-like Landau levels
The relativistic Landau levels in the layered organic material
alpha-(BEDT-TTF)_2I_3 [BEDT-TTF=bis(ethylenedithio)tetrathiafulvalene] are
sensitive to the tilt of the Dirac cones, which, as in the case of graphene,
determine the low-energy electronic properties under appropriate pressure. We
show that an applied inplane electric field, which happens to be in competition
with the tilt of the cones, lifts the twofold valley degeneracy due to a
different level spacing. The scenario may be tested in infrared transmission
spectroscopy.Comment: 4 pages, 1 figure; version with minor corrections published in EP
Multiband superconductivity in the heavy fermion compound PrOs4Sb12
The thermal conductivity of the heavy fermion superconductor PrOs4Sb12 was
measured down to Tc/40 throughout the vortex state. At lowest temperatures and
for magnetic fields H ~ 0.07Hc2, already 40% of the normal state thermal
conductivity is restored. This behaviour (similar to that observed in MgB2) is
a clear signature of multiband superconductivity in this compound.Comment: 12pages, version #1 20\_06\_200
Time Delays in the Synchronization of Chaotic Coupled Systems with Feedback
The synchronized excitable behavior of two coupled chaotic diode lasers with
feedback was experimental and numerically studied. We determine the relation
between the observed delay times in synchronized Low Frequency Fluctuation
spikes and the coupling and the feedback times in the lasers.Comment: 5 pages, 6 figure
On zero-point energy, stability and Hagedorn behavior of Type IIB strings on pp-waves
Type IIB strings on many pp-wave backgrounds, supported either by 5-form or
3-form fluxes, have negative light-cone zero-point energy. This raises the
question of their stability and poses possible problems in the definition of
their thermodynamic properties. After having pointed out the correct way of
calculating the zero-point energy, an issue not fully discussed in literature,
we show that these Type IIB strings are classically stable and have well
defined thermal properties, exhibiting a Hagedorn behavior.Comment: Latex, 13 pages. v2: regularization/renormalization prescription
clarified, refs. adde
Hyperon Nonleptonic Weak Decays Revisited
We first review the current algebra - PCAC approach to nonleptonic octet
baryon 14 weak decay B (\to) (B^{\prime})(\pi) amplitudes. The needed four
parameters are independently determined by (\Omega \to \Xi \pi),(\Lambda K) and
(\Xi ^{-}\to \Sigma ^{-}\gamma) weak decays in dispersion theory tree order. We
also summarize the recent chiral perturbation theory (ChPT) version of the
eight independent B (\to) (B^{\prime}\pi) weak (\Delta I) = 1/2 amplitudes
containing considerably more than eight low-energy weak constants in one-loop
order.Comment: 10 pages, RevTe
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