8 research outputs found
Towards a Robust Framework of Network Coordinate Systems
No full textPart 7: Network MappingInternational audienceNetwork Coordinate System (NCS) is an efficient and scalable mechanism to predict latency between any two network hosts based on historical measurements. Most NCS models, such as metric space embedding based, like Vivaldi, and matrix factorization based, like DMF and Phoenix, use squared error measure in training which suffers from the erroneous records, i.e. the records with large noise. To overcome this drawback, we introduce an elegant error measure, the Huber norm to network latency prediction. The Huber norm shows its robustness to the large data noise while remaining efficiency of optimization. Based on that, we upgrade the traditional NCS models into more robust versions, namely Robust Vivaldi model and Robust Matrix Factorization model. We conduct extensive experiments to compare the proposed models with traditional ones and the results show that our approaches significantly increase the accuracy of network latency prediction
DR3: Optimizing Site Selection for Global Load Balance in Application Delivery Controller
No full textBiomaterials: Disordered Topography Mediates Filopodial Extension and Morphology of Cells on Stiff Materials (Adv. Funct. Mater. 38/2017)
No full textBiomaterials: Disordered Topography Mediates Filopodial Extension and Morphology of Cells on Stiff Materials
No full text
Disordered Topography Mediates Filopodial Extension and Morphology of Cells on Stiff Materials
No full textIn cell–material interactions, cells use filopodia to sense external biochemical and mechanical cues, and subsequently dictate their survival. In an effort toward understanding how disordered topography of stiff materials influences filopodial recognition, diamond films with grain sizes varying from nano- to micrometers are fabricated for the investigation of osteoblast filopodial extension. Interestingly, straight filopodia with pronounced cell–substrate adhesion are observed on a nanocrystalline diamond (NCD) region, whereas filopodia on a microcrystalline diamond (MCD) surface only adhere to, and get deflected by, large diamond grains. More importantly, filopodia on NCD keep propagating with a constant velocity, whereas the same process takes place in a slow and intermittent manner on MCD. A theoretical model is also developed and it suggests that the contact between the disordered topography and the filopodial tip plays a key role in altering filopodial growth dynamics. In particular, it is predicted that large surface asperities can block the movement of the filopodial tip, delay its extension, and cause bending of the structure, in quantitative agreement with experimental observations. These findings reveal previously underappreciated effects of random, stiff topographies on the response of cells, and hence can provide new insights for the design of future implant biomaterials
Evolution of flat band and role of lattice relaxations in twisted bilayer graphene
No full textMagic-angle twisted bilayer graphene (MATBG) exhibits correlated phenomena
such as superconductivity and Mott insulating state related to the weakly
dispersing flat band near the Fermi energy. Beyond its moir\'e period, such
flat band is expected to be sensitive to lattice relaxations. Thus, clarifying
the evolution of the electronic structure with twist angle is critical for
understanding the physics of MATBG. Here, we combine nanospot angle-resolved
photoemission spectroscopy and atomic force microscopy to resolve the fine
electronic structure of the flat band and remote bands, and their evolution
with twist angles from 1.07 to 2.60. Near the magic angle,
dispersion is characterized by a flat band near the Fermi energy with a
strongly reduced bandwidth. Moreover, near 1.07, we observe a spectral
weight transfer between remote bands at higher binding energy and extract the
modulated interlayer spacing near the magic angle. Our work provides direct
spectroscopic information on flat band physics and highlights the role of
lattice relaxations.Comment: 22 pages, 5 figures, Nature Materials, in pres
Metal Nanoparticle Harvesting by Continuous Rotating Electrodeposition and Separation
No full textCurrent synthetic approaches to metal nanoparticles are mostly batch processes that use a large quantity of reagents and surfactants, producing enormous amount of solid and liquid waste. Here, we developed a rotating electrodeposition and separation (REDS) technique, which entails electrochemically depositing nanoparticles onto a continuously rotating metal foil and subsequently harvesting them through mechanical delamination. A wide array of elemental nanoparticles (e.g., Ag, Au, Ni, Cu), alloys nanoparticles (e.g., FeCoNi and FeCoNiW), and metal oxide nanomaterials (e.g., Co3O4) were synthesized by REDS. We further controlled the growth direction of metals during the electrodeposition to fabricate more complex structures such as polyhedrons, nanoplates, dendrites, and flower nanostructures. Based on the metallic nanoparticles, we obtained conducting inks and fabricated near-field communication tags and touch screen panels. Our technique provides a novel approach for rapid, scalable, and green preparation of low-cost and high-quality nanoparticles in which electrodeposition chemistry can be controlled with a roll-to-roll system.</p
