277 research outputs found
Fast Landmark Localization with 3D Component Reconstruction and CNN for Cross-Pose Recognition
Two approaches are proposed for cross-pose face recognition, one is based on
the 3D reconstruction of facial components and the other is based on the deep
Convolutional Neural Network (CNN). Unlike most 3D approaches that consider
holistic faces, the proposed approach considers 3D facial components. It
segments a 2D gallery face into components, reconstructs the 3D surface for
each component, and recognizes a probe face by component features. The
segmentation is based on the landmarks located by a hierarchical algorithm that
combines the Faster R-CNN for face detection and the Reduced Tree Structured
Model for landmark localization. The core part of the CNN-based approach is a
revised VGG network. We study the performances with different settings on the
training set, including the synthesized data from 3D reconstruction, the
real-life data from an in-the-wild database, and both types of data combined.
We investigate the performances of the network when it is employed as a
classifier or designed as a feature extractor. The two recognition approaches
and the fast landmark localization are evaluated in extensive experiments, and
compared to stateof-the-art methods to demonstrate their efficacy.Comment: 14 pages, 12 figures, 4 table
Strange metal electrodynamics across the phase diagram of Bi<sub>2-<i>x</i></sub>Pb<sub><i>x</i></sub>Sr<sub>2-<i>y</i></sub>La<sub><i>y</i></sub>CuO<sub>6+<i>δ</i></sub> cuprates
Unlocking the mystery of the strange metal state has become the focal point of high-Tcresearch, not because of its importance for superconductivity, but because it appears to represent a truly novel phase of matter dubbed "quantum supreme matter. " Detected originally through high magnetic field, transport experiments, signatures of this phase have now been uncovered with a variety of probes. Our high resolution optical data of the low-Tccuprate superconductor, Bi2-xPbxSr2-yLayCuO6+delta allows us to probe this phase over a large energy and temperature window. We demonstrate that the optical signatures of the strange metal phase persist throughout the phase diagram. The strange metal signatures in the optical conductivity are twofold: (i) a low energy Drude response with Drude width on the order of temperature and (ii) a high energy conformal tail with a doping dependent power-law exponent. While the Drude weight evolves monotonically throughout the entire doping range studied, the spectral weight contained in the high energy conformal tail appears to be doping and temperature independent. Our analysis further shows that the temperature dependence of the optical conductivity is completely determined by the Drude parameters. Our results indicate that there is no critical doping level inside the superconducting dome where the carrier density starts to change drastically and that the previously observed "return to normalcy " is a consequence of the increasing importance of the Drude component relative to the conformal tail with doping. Importantly, both the doping and temperature dependence of the resistivity are largely determined by the Drude width
Insights into the single cell draft genome of "Candidatus Achromatium palustre"
"Candidatus Achromatium palustre" was recently described as the first marine representative of the Achromatium spp. in the Thiotrichaceae - a sister lineage to the Chromatiaceae in the Gammaproteobacteria. Achromatium spp. belong to the group of large sulfur bacteria as they can grow to nearly 100 μm in size and store elemental sulfur (S0) intracellularly. As a unique feature, Achromatium spp. can accumulate colloidal calcite (CaCO3) inclusions in great amounts. Currently, both process and function of calcite accumulation in bacteria is unknown, and all Achromatium spp. are uncultured. Recently, three single-cell draft genomes of Achromatium spp. from a brackish mineral spring were published, and here we present the first draft genome of a single "Candidatus Achromatium palustre" cell collected in the sediments of the Sippewissett Salt Marsh, Cape Cod, MA. Our draft dataset consists of 3.6 Mbp, has a G + C content of 38.1 % and is nearly complete (83 %). The next closest relative to the Achromatium spp. genomes is Thiorhodovibrio sp. 907 of the family Chromatiaceae, containing phototrophic sulfide-oxidizing bacteria
Incoherent transport across the strange metal regime of highly overdoped cuprates
Strange metals possess highly unconventional transport characteristics, such
as a linear-in-temperature () resistivity, an inverse Hall angle that varies
as and a linear-in-field () magnetoresistance. Identifying the origin
of these collective anomalies has proved profoundly challenging, even in
materials such as the hole-doped cuprates that possess a simple band structure.
The prevailing dogma is that strange metallicity in the cuprates is tied to a
quantum critical point at a doping inside the superconducting dome. Here,
we study the high-field in-plane magnetoresistance of two superconducting
cuprate families at doping levels beyond . At all dopings, the
magnetoresistance exhibits quadrature scaling and becomes linear at high
ratios. Moreover, its magnitude is found to be much larger than predicted by
conventional theory and insensitive to both impurity scattering and magnetic
field orientation. These observations, coupled with analysis of the zero-field
and Hall resistivities, suggest that despite having a single band, the cuprate
strange metal phase hosts two charge sectors, one containing coherent
quasiparticles, the other scale-invariant `Planckian' dissipators.Comment: 15 pages plus 7 figures (including Supplementary Information
Non-Fermi liquid transport in the vicinity of nematic quantum critical point of FeSeS superconductor
Non-Fermi liquids are strange metals whose physical properties deviate
qualitatively from those of conventional metals due to strong quantum
fluctuations. In this paper, we report transport measurements on the
FeSeS superconductor, which has a quantum critical point of a
nematic order without accompanying antiferromagnetism. We find that in addition
to a linear-in-temperature resistivity , which is close to
the Planckian limit, the Hall angle varies as
and the low-field magnetoresistance is well scaled as
in the vicinity of the
nematic quantum critical point. This set of anomalous charge transport
properties shows striking resemblance with those reported in cuprate,
iron-pnictide and heavy fermion superconductors, demonstrating that the
critical fluctuations of a nematic order with can also lead
to a breakdown of the Fermi liquid description.Comment: 8 pages, 4 + 1 figure
- …