Cluster observations of the midaltitude cusp under strong northward interplanetary magnetic field

We report on a multispacecraft cusp observation lasting more than 100 min. We determine the cusp boundary motion and reveal the effect on the cusp size of the interplanetary magnetic field (IMF) changing from southward to northward. The cusp shrinks at the beginning of the IMF rotation and it reexpands at the rate of 0.40° invariant latitude per hour under stable northward IMF. On the basis of plasma signatures inside the cusp, such as counterstreaming electrons with balanced fluxes, we propose that pulsed dual lobe reconnection operates during the time of interest. SC1 and SC4 observations suggest a long-term regular periodicity of the pulsed dual reconnection, which we estimate to be ~1–5 min. Further, the distances from the spacecraft to the reconnection site are estimated on the basis of observations from three satellites. The distance determined using SC1 and SC4 observations is ~15 RE and that determined from SC3 data is ~8 RE. The large-scale speed of the reconnection site sunward motion is ~16 km s-1. We observe also a fast motion of the reconnection site by SC1, which provides new information about the transitional phase after the IMF rotation. Finally, a statistical study of the dependency of plasma convection inside the cusp on the IMF clock angle is performed. The relationship between the cusp stagnation, the dual lobe reconnection process, and the IMF clock angle is discussed

Giant Negative Thermal Expansion Induced by the Synergistic Effects of Ferroelectrostriction and Spin-Crossover in PbTiO3-Based Perovskites

The discovery of unusual negative thermal expansion (NTE) provides the opportunity to control the common but much desired property of thermal expansion, which is valuable not only in scientific interests but also in practical applications. However, most of the available NTE materials are limited to a narrow temperature range, and the NTE effect is generally weakened by means of various modifications. Here, we report an enhanced NTE effect that occurs over a wide temperature range (\alpha V = -5.24 * 10-5 {\deg}C^-1, 25-575 {\deg} C), and this NTE effect is accompanied by an abnormal enhanced tetragonality, a large spontaneous polarization, and a G-type antiferromagnetic ordering in the present perovskite-type ferroelectric of (1-x)PbTiO3-xBiCoO3. Specifically, for the composition of 0.5PbTiO3-0.5BiCoO3, an extensive volumetric contraction of ~4.8 % has been observed near the Curie temperature of 700 {\deg}C, which represents the highest level in PbTiO3-based ferroelectrics. According to our experimental and theoretical results, the giant NTE originates from a synergistic effect of the ferroelectrostriction and spin-crossover of cobalt on the crystal lattice. The actual NTE mechanism is contrasted with previous functional NTE materials, in which the NTE is simply coupled with one ordering such as electronic, magnetic, or ferroelectric ordering. The present study sheds light on the understanding of NTE mechanisms and it attests that NTE could be simultaneouslycoupled with different orderings, which will pave a new way toward the design of large NTE materials.Comment: 30 page

Magnetic Field Effect in Josephson tunneling between d-Wave Superconductors

The magnetic field effect in the Josephson tunneling between two d-wave superconductors are investigated. When the crystal orientation of one (or each) superconductor relative to the interface normal is such that midgap states exist at the interface, there is a component of the tunneling current due to the midgap states. For a junction with a flat {001}|{110} or {100}|{110} interface, this component is the predominant contribution to the current. The predicted current-field dependence differs entirely from the conventional Fraunhofer pattern, in agreement with a published measurement. This is because, apart from the Fraunhofer factor, the critical current depends on the magnetic field B through the current density also which is a linear function of B for weak B.Comment: 5 pages, 2 figure

Real Scalar Field Scattering with Polynomial Approximation around Schwarzschild-de Sitter Black-hole

As one of the fitting methods, the polynomial approximation is effective to process sophisticated problem. In this paper, we employ this approach to handle the scattering of scalar field around the Schwarzschild-de Sitter black-hole. The complex relationship between tortoise coordinate and radial coordinate is replaced by the approximate polynomial. The Schr$\ddot{o}$dinger-like equation, the real boundary conditions and the polynomial approximation construct a full Sturm-Liouville type problem. Then this boundary value problem can be solved numerically according to two limiting cases: the first one is the Nariai black-hole whose horizons are close to each other, the second one is when the horizons are widely separated. Compared with previous results (Brevik and Tian), the field near the event horizon and cosmological horizon can have a better description.Comment: revtex4 source file, 11 pages, 8 figure

Parallel momentum distribution of the 28^{28}Si fragments from 29^{29}P

Distribution of the parallel momentum of $^{28}$Si fragments from the breakup of 30.7 MeV/nucleon $^{29}$P has been measured on C targets. The distribution has the FWHM with the value of 110.5 $\pm$ 23.5 MeV/c which is consistent quantitatively with Galuber model calculation assuming by a valence proton in $^{29}$P. The density distribution is also predicted by Skyrme-Hartree-Fock calculation. Results show that there might exist the proton-skin structure in $^{29}$P.Comment: 4 pages, 4 figure

Maps: Model-based analysis of long-range chromatin interactions from PLAC-seq and HiChIP experiments

Hi-C and chromatin immunoprecipitation (ChIP) have been combined to identify long-range chromatin interactions genome-wide at reduced cost and enhanced resolution, but extracting information from the resulting datasets has been challenging. Here we describe a computational method, MAPS, Model-based Analysis of PLAC-seq and HiChIP, to process the data from such experiments and identify long-range chromatin interactions. MAPS adopts a zero-truncated Poisson regression framework to explicitly remove systematic biases in the PLAC-seq and HiChIP datasets, and then uses the normalized chromatin contact frequencies to identify significant chromatin interactions anchored at genomic regions bound by the protein of interest. MAPS shows superior performance over existing software tools in the analysis of chromatin interactions from multiple PLAC-seq and HiChIP datasets centered on different transcriptional factors and histone marks

Point contact spectroscopy of the electron-doped cuprate superconductor Pr{2-x}Ce{x}CuO4: The dependence of conductance-voltage spectra on cerium doping, barrier strength and magnetic field

We present conductance-voltage (G-V) data for point contact junctions between a normal metal and the electron doped cuprate superconductor Pr{2-x}Ce{x}CuO4 (PCCO). We observe a zero bias conductance peak (ZBCP) for the under-doped composition of this cuprate (x=0.13) which is consistent with d-wave pairing symmetry. For optimally-doped (x=0.15) and over-doped (x=0.17) PCCO, we find that the G-V characteristics indicate the presence of an order parameter without nodes. We investigate this further by obtaining point contact spectroscopy data for different barrier strengths and as a function of magnetic field.Comment: 13 pages, 9 figure

Chalcogenide Glass-on-Graphene Photonics

Two-dimensional (2-D) materials are of tremendous interest to integrated photonics given their singular optical characteristics spanning light emission, modulation, saturable absorption, and nonlinear optics. To harness their optical properties, these atomically thin materials are usually attached onto prefabricated devices via a transfer process. In this paper, we present a new route for 2-D material integration with planar photonics. Central to this approach is the use of chalcogenide glass, a multifunctional material which can be directly deposited and patterned on a wide variety of 2-D materials and can simultaneously function as the light guiding medium, a gate dielectric, and a passivation layer for 2-D materials. Besides claiming improved fabrication yield and throughput compared to the traditional transfer process, our technique also enables unconventional multilayer device geometries optimally designed for enhancing light-matter interactions in the 2-D layers. Capitalizing on this facile integration method, we demonstrate a series of high-performance glass-on-graphene devices including ultra-broadband on-chip polarizers, energy-efficient thermo-optic switches, as well as graphene-based mid-infrared (mid-IR) waveguide-integrated photodetectors and modulators

SALL1 enforces microglia-specific DNA binding and function of SMADs to establish microglia identity

Spalt-like transcription factor 1 (SALL1) is a critical regulator of organogenesis and microglia identity. Here we demonstrate that disruption of a conserved microglia-specific super-enhancer interacting with the Sall1 promoter results in complete and specific loss of Sall1 expression in microglia. By determining the genomic binding sites of SALL1 and leveraging Sall1 enhancer knockout mice, we provide evidence for functional interactions between SALL1 and SMAD4 required for microglia-specific gene expression. SMAD4 binds directly to the Sall1 super-enhancer and is required for Sall1 expression, consistent with an evolutionarily conserved requirement of the TGFβ and SMAD homologs Dpp and Mad for cell-specific expression of Spalt in the Drosophila wing. Unexpectedly, SALL1 in turn promotes binding and function of SMAD4 at microglia-specific enhancers while simultaneously suppressing binding of SMAD4 to enhancers of genes that become inappropriately activated in enhancer knockout microglia, thereby enforcing microglia-specific functions of the TGFβ–SMAD signaling axis.</p