19,661 research outputs found
Pinning of stripes by local structural distortions in cuprate high-Tc superconductors
We study the spin-density wave (stripe) instability in lattices with mixed
low-temperature orthorhombic (LTO) and low-temperature tetragonal (LTT) crystal
symmetry. Within an explicit mean-field model it is shown how local LTT regions
act as pinning centers for static stripe formation. We calculate the
modulations in the local density of states near these local stripe regions and
find that mainly the coherence peaks and the van Hove singularity (VHS) are
spatially modulated. Lastly, we use the real-space approach to simulate recent
tunneling data in the overdoped regime where the VHS has been detected by
utilizing local normal state regions.Comment: Conference proceedings for Stripes1
A Convex Reconstruction Model for X-ray Tomographic Imaging with Uncertain Flat-fields
Classical methods for X-ray computed tomography are based on the assumption
that the X-ray source intensity is known, but in practice, the intensity is
measured and hence uncertain. Under normal operating conditions, when the
exposure time is sufficiently high, this kind of uncertainty typically has a
negligible effect on the reconstruction quality. However, in time- or
dose-limited applications such as dynamic CT, this uncertainty may cause severe
and systematic artifacts known as ring artifacts. By carefully modeling the
measurement process and by taking uncertainties into account, we derive a new
convex model that leads to improved reconstructions despite poor quality
measurements. We demonstrate the effectiveness of the methodology based on
simulated and real data sets.Comment: Accepted at IEEE Transactions on Computational Imagin
Three-loop HTL QCD thermodynamics
The hard-thermal-loop perturbation theory (HTLpt) framework is used to
calculate the thermodynamic functions of a quark-gluon plasma to three-loop
order. This is the highest order accessible by finite temperature perturbation
theory applied to a non-Abelian gauge theory before the high-temperature
infrared catastrophe. All ultraviolet divergences are eliminated by
renormalization of the vacuum, the HTL mass parameters, and the strong coupling
constant. After choosing a prescription for the mass parameters, the three-loop
results for the pressure and trace anomaly are found to be in very good
agreement with recent lattice data down to , which are
temperatures accessible by current and forthcoming heavy-ion collision
experiments.Comment: 27 pages, 11 figures; corresponds with published version in JHE
Electrolysis-based diaphragm actuators
This work presents a new electrolysis-based microelectromechanical systems (MEMS) diaphragm actuator. Electrolysis is a technique for converting electrical energy to pneumatic energy. Theoretically electrolysis can achieve a strain of 136 000% and is capable of generating a pressure above 200 MPa. Electrolysis actuators require modest electrical power and produce minimal heat. Due to the large volume expansion obtained via electrolysis, small actuators can create a large force. Up to 100 µm of movement was achieved by a 3 mm diaphragm. The actuator operates at room temperature and has a latching and reversing capability
Reorganization and participation in decentralized platform ecosystems: evidence from blockchain forking
Like any organizational system, platform ecosystems reorganize to update its alignment with the internal and external environments. However, unlike reorganizations of centrally managed platforms performed by the owners, reorganizations of decentralized platforms ecosystems do not rely on formal authority. Instead, the network self-reorganizes to renew the structure, rules, and information to evolve. Little is known about how self-reorganizations influence the participation of various types of networks. In this study, we investigate nine reorganization events on Ethereum, a blockchain-based decentralized smart contract platform, to unpack how self-reorganization related to hard forking influence participation in the development, validation, transaction, and complementor networks. We find that, while participation increases across all networks show a small increase after hard forking events, more complex dynamics are at play within each network that builds on delicate trade-offs between participation structure, configuration, and incentives. Our findings have implications for blockchain research as well as for start-ups building decentralized applications on top of decentralized smart contract platforms
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