1,179 research outputs found
Nonlinear conductance of nanowires - A signature of Luttinger liquid effects?
We analyze recent measurements of the room temperature current-voltage
characteristics of gold nanowires, whose zero current conductance is quantized
in units of . A faster than linear increase of current with voltage was
observed at low voltages beginning from V. We analyze the nonlinear
behavior in terms of a dynamic Coulomb blockade of conducting modes and show
that it may be explained as a Luttinger-liquid effect.Comment: 13 pages, latex with supplied stylefile, 3 figures in eps format,
submitted to Superlattices and Microstructure
Electroweak and Top physics at ATLAS
The observations of electroweak boson (W, Z) and top quark pair (t¯t) production are among the key milestones for the early LHC physics programme. Production of t¯t, W and Z in association with jets are important backgrounds in various searches for physics beyond the Standard Model, and new physics may also give rise to additional production mechanisms or modification of the decay channels. This note summarizes √ the electroweak and top physics performed in ATLAS with Vs = 7TeV proton-proton collisions during 2010 and compares the observations with theoretical predictions
Picosecond time-resolved energy transfer within C-phycocyanin aggregates of Mastigocladus laminosus
We have investigated by picosecond absorption experiments how the size of C-phycocyanin aggregates from Mastigocladus laminosus influences the excitation energy transfer kinetics. Going from C-phycocyanin monomers to trimers the lifetime of the faster energy transfer component decreased from 57 ± 4 to 27 ± 4 ps over most of the wavelength range (580–645 nm) studied. This change was interpreted as the opening of fast transfer channels (α-84 → β-84 and/or β-84 → β-84) between two adjacent monomers in the trimeric unit. The 57 ps lifetime is probably due mainly to the β-155 → β-84 energy transfer step. The intermediate lifetime decreased from about 300 ps in the monomer to 100–120 ps in the trimer. The former is believed to be dominated by the equilibration process α-84 a3 β-84, while the latter probably represents the time required for the excitation energy to reach thermodynamic equilibrium within the trimer. The lifetime of the longest components was about 1 ns in both systems. This indicates that the chromophores in these C-phycocyanin complexes are more exposed to non-radiative processes (like, for instance, isomerization) compared to the chromophores in intact phycobilisomes, where this lifetime typically is about 1.8 ns. The anisotropy relaxation closely followed the isotropic lifetimes in both systems. The anisotropy after the initial fast relaxation, r(∞), was 0.29 ± 0.04 in monomers and decreased to 0.15 ± 0.03 in trimers. Measurements of the steady-state fluorescence excitation anisotropy gave the same results within the experimental error
Picosecond time-resolved energy transfer kinetics within C-phycocyanin and allophycocyanin aggregates
Point-SLAM: Dense Neural Point Cloud-based SLAM
We propose a dense neural simultaneous localization and mapping (SLAM)
approach for monocular RGBD input which anchors the features of a neural scene
representation in a point cloud that is iteratively generated in an
input-dependent data-driven manner. We demonstrate that both tracking and
mapping can be performed with the same point-based neural scene representation
by minimizing an RGBD-based re-rendering loss. In contrast to recent dense
neural SLAM methods which anchor the scene features in a sparse grid, our
point-based approach allows dynamically adapting the anchor point density to
the information density of the input. This strategy reduces runtime and memory
usage in regions with fewer details and dedicates higher point density to
resolve fine details. Our approach performs either better or competitive to
existing dense neural RGBD SLAM methods in tracking, mapping and rendering
accuracy on the Replica, TUM-RGBD and ScanNet datasets. The source code is
available at https://github.com/tfy14esa/Point-SLAM.Comment: 17 Pages, 10 Figure
UncLe-SLAM: Uncertainty Learning for Dense Neural SLAM
We present an uncertainty learning framework for dense neural simultaneous
localization and mapping (SLAM). Estimating pixel-wise uncertainties for the
depth input of dense SLAM methods allows re-weighing the tracking and mapping
losses towards image regions that contain more suitable information that is
more reliable for SLAM. To this end, we propose an online framework for sensor
uncertainty estimation that can be trained in a self-supervised manner from
only 2D input data. We further discuss the advantages of the uncertainty
learning for the case of multi-sensor input. Extensive analysis,
experimentation, and ablations show that our proposed modeling paradigm
improves both mapping and tracking accuracy and often performs better than
alternatives that require ground truth depth or 3D. Our experiments show that
we achieve a 38\% and 27\% lower absolute trajectory tracking error (ATE) on
the 7-Scenes and TUM-RGBD datasets respectively. On the popular Replica dataset
using two types of depth sensors, we report an 11\% F1-score improvement on
RGBD SLAM compared to the recent state-of-the-art neural implicit approaches.
Source code: https://github.com/kev-in-ta/UncLe-SLAM.Comment: ICCV 2023 Workshop. 20 pages, 9 figure
Palaeobiology, ecology, and distribution of stromatoporoid faunas in biostromes of the mid-Ludlow of Gotland
Six well exposed mid−Ludlow stromatoporoid−dominated reef biostromes in four localities from the Hemse Group in southeastern Gotland, Sweden comprise a stromatoporoid assemblage dominated by four species; Clathrodictyon mohicanum, “Stromatopora” bekkeri, Plectostroma scaniense, and Lophiostroma schmidtii. All biostromes investigated in this area (of approximately 30 km2) are interpreted to belong to a single faunal assemblage forming a dense accumulation of fossils that is probably the best exposed stromatoporoid−rich deposit of the Silurian. The results from this comprehensive study strengthen earlier interpretations of a combination of genetic and environmental control on growth−forms of the stromatoporoids. Growth styles are similar for stromatoporoids in all six biostromes. Differences in biostrome fabric are due to variations in the degree of disturbance by storms. The uniformity of facies and the widespread low−diversity fauna support the view that palaeoenvironmental conditions were similar across the area where these biostromes crop out, and promoted the extraordinary growth of stromatoporoids in this shallow shelf area
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