25,431 research outputs found

    Shortcuts to adiabaticity for an ion in a rotating radially-tight trap

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    We engineer the fast rotation of a quantum particle confined in an effectively one-dimensional, harmonic trap, for a predetermined rotation angle and time, avoiding final excitation. Different schemes are proposed with different speed limits that depend on the control capabilities. We also make use of trap rotations to create squeezed states without manipulating the trap frequencies.Comment: 11 pages, 6 figure

    Exothermic isospin-violating dark matter after SuperCDMS and CDEX

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    We show that exothermic isospin-violating dark matter (IVDM) can make the results of the latest CDMS-Si experiment consistent with recent null experiments, such as XENON10, XENON100, LUX, CDEX, and SuperCDMS, whereas for the CoGeNT experiment, a strong tension still persists. For CDMS-Si, separate exothermic dark matter or isospin-violating dark matter cannot fully ameliorate the tensions among these experiments; the tension disappears only if exothermic scattering is combined with an isospin-violating effect of f_n/f_p=-0.7. For such exothermic IVDM to exist, at least a new vector gauge boson (dark photon or dark Z') that connects SM quarks to Majorana-type DM particles is required.Comment: 12 pages, 6 figure

    Self-crimping bicomponent nanofibres electrospun from polyacrylonitrile and elastomeric polyurethane

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    Two polymer solutions were brought together via a microfluidic device and subjected to an electrospinning process. The two polymer solutions flowed into the microfluidic channel side-by-side with very little intermixing due to their laminar nature. High speed stretching of the polymer solutions resulted in side-by-side bicomponent fibres. The electrospun nanofibres exhibited an extremely high propensity to self-crimp when an elastomeric polymer (polyurethane) and a normal polymer (polyacrylonitrile PAN) were involved in the electrospinning process. The formation of self-crimping fibre morphology was attributed to the differential shrinkage of the two polymers.<br /

    Polarizing Lamp

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    A polarizing lamp includes a polarization beam splitter, a metallic grating reflector having metallic gratings with a trapezoidal profile, and an unpolarized light source positioned between the polarization beam splitter and the metallic grating reflector

    Structural insights into the gating of DNA passage by the topoisomerase II DNA-gate.

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    Type IIA topoisomerases (Top2s) manipulate the handedness of DNA crossovers by introducing a transient and protein-linked double-strand break in one DNA duplex, termed the DNA-gate, whose opening allows another DNA segment to be transported through to change the DNA topology. Despite the central importance of this gate-opening event to Top2 function, the DNA-gate in all reported structures of Top2-DNA complexes is in the closed state. Here we present the crystal structure of a human Top2 DNA-gate in an open conformation, which not only reveals structural characteristics of its DNA-conducting path, but also uncovers unexpected yet functionally significant conformational changes associated with gate-opening. This structure further implicates Top2's preference for a left-handed DNA braid and allows the construction of a model representing the initial entry of another DNA duplex into the DNA-gate. Steered molecular dynamics calculations suggests the Top2-catalyzed DNA passage may be achieved by a rocker-switch-type movement of the DNA-gate

    Wide-Angle and Broadband Polarization Converter

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    Apparatus and methods for a polarization converter comprising a polarization beam splitter for receiving an input light beam and allows a transverse magnetic to pass through the polarization beam splitter and reflects a transverse electric wave and a diffraction grating having a reflectivity and polarization convertible grating for receiving the transverse electric wave reflects back a reflected transverse electric wave having a polarization rotation. The broadband wide-angle polarization beam splitter can be alternative optical elements such as a prism or an optical device having multi-layered films. The diffraction grating can be a diffraction grating having alternating parallel protrusions and recesses, metallic diffraction grating, metal-coated diffraction grating, metal-coated multi-layered diffraction grating, non-metallic reflective material surface grating, volume grating, a multi-layer grating, diffractive grating having sub-wavelength grating periods or diffractive grating h

    Liquid Crystal Display with Different Twisting Directions of Liquid Crystal Molecules

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    A liquid crystal display includes a first alignment film having a first alignment direction, a second alignment film having a second alignment direction, and a liquid crystal layer having liquid crystal molecules between the first and second alignment films. The liquid crystal layer is doped with a chiral material that tends to induce a first twist in directors of the liquid crystal molecules when an electric field is applied to the liquid crystal layer. The first and second alignment films have orientations that tends to induce a second twist in the directors when an electric field is applied to the liquid crystal layer, in which the direction of the first twist is different from the direction of the second twist
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