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  1. Abstract

    The current best upper limit for electron electric dipole moment (EDM), |de| < 1.1 × 10−29e cm (90% confidence), was set by the ACME Collaboration in 2018. The ACME experiment uses a spin-precession measurement in a cold beam of thorium monoxide (ThO) molecules to detectde. An improvement in statistical uncertainty would be possible with more efficient use of molecules from the cryogenic buffer gas beam source. Here, we demonstrate electrostatic focusing of the ThO beam with a hexapole lens. This results in a factor of 16 enhancement in the molecular flux detectable downstream, in a beamline similar to that built for the next generation of ACME. We also demonstrate an upgraded rotational cooling scheme that increases the ground state population by 3.5 times compared to no cooling, consistent with expectations and a factor of 1.4 larger than previously in ACME. When combined with other demonstrated improvements, we project over an order of magnitude improvement in statistical sensitivity for the next generation ACME electron EDM search.

  2. A concentration-gradient composition is proposed as an effective approach to solve the mechanical degradation and improve the electrochemical cyclability for cathodes of sodium-ion batteries. Concentration-gradient shell NaxNiyMn1-yFe(CN)6·nH2O, in which the Ni content gradually increases from the interior to the particle surface, is synthesized by a facile co-precipitation process. The as-obtained cathode exhibits an improved electrochemical performance compared to homogeneous NaxMnFe(CN)6·nH2O, delivering a high reversible specific capacity of 110 mA h g-1 at 0.2 C and outstanding cycling stability (93% retention after 1000 cycles at 5 C). The improvement of electrochemical performance can be attributed to its robust microstructure that effectively alleviates the electrochemically induced stresses and accumulated damage during sodiation/desodiation and thus prevents the initiation of fracture in the particles upon long term cycling. These findings render a prospective strategy to develop high-performance electrode materials for sodium-ion batteries.
  3. Face detection and recognition benchmarks have shifted toward more difficult environments. The challenge presented in this paper addresses the next step in the direction of automatic detection and identification of people from outdoor surveillance cameras. While face detection has shown remarkable success in images collected from the web, surveillance cameras include more diverse occlusions, poses, weather conditions and image blur. Although face verification or closed-set face identification have surpassed human capabilities on some datasets, open-set identification is much more complex as it needs to reject both unknown identities and false accepts from the face detector. We show that unconstrained face detection can approach high detection rates albeit with moderate false accept rates. By contrast, open-set face recognition is currently weak and requires much more attention.