37,633 research outputs found
Variational formulas of higher order mean curvatures
In this paper, we establish the first variational formula and its
Euler-Lagrange equation for the total -th mean curvature functional
of a submanifold in a general Riemannian manifold
for . As an example, we prove that closed
complex submanifolds in complex projective spaces are critical points of the
functional , called relatively -minimal submanifolds,
for all . At last, we discuss the relations between relatively -minimal
submanifolds and austere submanifolds in real space forms, as well as a special
variational problem.Comment: 13 pages, to appear in SCIENCE CHINA Mathematics 201
[Colored solutions of Yang-Baxter equation from representations of U_{q}gl(2)]
We study the Hopf algebra structure and the highest weight representation of
a multiparameter version of . The commutation relations as well as
other Hopf algebra maps are explicitly given. We show that the multiparameter
universal matrix can be constructed directly as a quantum double
intertwiner, without using Reshetikhin's transformation. An interesting feature
automatically appears in the representation theory: it can be divided into two
types, one for generic , the other for being a root of unity. When
applying the representation theory to the multiparameter universal
matrix, the so called standard and nonstandard colored solutions of the Yang-Baxter equation is obtained.Comment: [14]pages, latex, no figure
Effects of dust storms on microwave radiation based on satellite observation and model simulation over the Taklamakan desert
International audienceEffects of dust particles on microwave radiation over the Taklamakan desert are studied with use of measurements from the Advanced Microwave Scanning Radiometer (AMSR-E) on the EOS Aqua satellite and a microwave radiation transfer model. Eight observed cases show that the signal from atmospheric dust can be separated from the surface radiation by the fact that the dust particles produce stronger scattering at high frequencies and depolarize the background desert signature. This result of satellite data is consistent with the model simulation
Two-qubit Quantum Logic Gate in Molecular Magnets
We proposed a scheme to realize a controlled-NOT quantum logic gate in a
dimer of exchange coupled single-molecule magnets, . We
chosen the ground state and the three low-lying excited states of a dimer in a
finite longitudinal magnetic field as the quantum computing bases and
introduced a pulsed transverse magnetic field with a special frequency. The
pulsed transverse magnetic field induces the transitions between the quantum
computing bases so as to realize a controlled-NOT quantum logic gate. The
transition rates between the quantum computing bases and between the quantum
computing bases and other excited states are evaluated and analyzed.Comment: 7 pages, 2 figure
A chemical mutagenesis approach to insert post-translational modifications in aggregation-prone proteins
Neurodegenerative diseases are a class of disorders linked to the formation in the nervous system of fibrillar protein aggregates called amyloids. This aggregation process is affected by a variety of post-translational modifications, whose specific mechanisms are not fully understood yet. Emerging chemical mutagenesis technology is currently striving to address the challenge of introducing protein post-translational modifications, while maintaining the stability and solubility of the proteins during the modification reaction. Several amyloidogenic proteins are highly aggregation-prone, and current modification procedures can lead to unexpected precipitation of these proteins, affecting their yield and downstream characterization. Here, we present a method for maintaining amyloidogenic protein solubility during chemical mutagenesis. As proof-of-principle, we applied our method to mimic the phosphorylation of serine-26 and the acetylation of lysine-28 of the 40-residue long variant of amyloid-β peptide, whose aggregation is linked to Alzheimer’s disease
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Development of Novel EBSM System for High-Tech Material Additive Manufacturing Research
Electron beam is more appropriate for metal additive manufacturing (AM) than laser
because of its high energy converting efficiency and high absorption for various materials. It
becomes a preference for AM study of high-tech material with high melting point, high
brittleness or graded material. A novel electron beam selective melting (EBSM) system with
dual-material processing capability has been developed in Tsinghua University to meet the wide
high-tech material AM research requirement. A vibration driven powder supplier was developed
and the supplier had a high compatibility to various powders. A stable supplying rate and a
supplying accuracy less than 7.5% were obtained with the supplier. Two powders can be supplied
individually to obtain a mixture with tailored proportion for each powder layer. The mixture is
homogenous and the actual proportion is close to the desired value. In order to prolong the
spreading comb’s lifetime and avoid tooth breaking, a low deformation powder spreading device
was designed based on dual inclined combs and a one-way scraping mechanism. The system
provides exchangeable building tanks with sizes of 100 ×100 ×100 mm3
and 250 × 250 × 250
mm3, which can save powder when the part is small and the powder is expensive. The novel
EBSM system is capable of building parts with single material and has a potential of
dual-material processing.Mechanical Engineerin
Measuring the leptonic CP phase in neutrino oscillations with nonunitary mixing
Non-unitary neutrino mixing implies an extra CP violating phase that can fake the leptonic Dirac CP phase δCP of the simplest three-neutrino mixing benchmark scheme. This would hinder the possibility of probing for CP violation in accelerator-type experiments. We take T2K and T2HK as examples to demonstrate the degeneracy between the "standard" (or "unitary") and "non-unitary" CP phases. We find, under the assumption of non-unitary mixing, that their CP sensitivities severely deteriorate. Fortunately, the TNT2K proposal of supplementing T2(H)K with a µDAR source for better measurement of δCP can partially break the CP degeneracy by probing both cos δCP and sin δCP dependences in the wide spectrum of the µDAR flux. We also show that the further addition of a near detector to the µDAR setup can eliminate the degeneracy completely
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