Antiferromagnetic Domain Wall Engineering in Chromium Films

We have engineered an antiferromagnetic domain wall by utilizing a magnetic frustration effect of a thin iron cap layer deposited on a chromium film. Through lithography and wet etching we selectively remove areas of the Fe cap layer to form a patterned ferromagnetic mask over the Cr film. Removing the Fe locally removes magnetic frustration in user-defined regions of the Cr film. We present x-ray microdiffraction microscopy results confirming the formation of a 90{\deg} spin-density wave propagation domain wall in Cr. This domain wall nucleates at the boundary defined by our Fe mask.Comment: submitted to AP

MeerKAT HI line observations of the nearby interacting galaxy pair NGC 1512/1510

We present MeerKAT HI line observations of the nearby interacting galaxy pair NGC 1512/1510. The MeerKAT data yield high-fidelity image sets characterised by an excellent combination of high angular resolution (~20") and and sensitivity (~0.08 Msun/pc^2), thereby offering the most detailed view of this well-studied system's neutral atomic hydrogen content, especially the HI co-located with the optical components of the galaxies. The stellar bulge and bar of NGC 1512 are located within a central HI depression where surface densities fall below 1 Msun/pc^2, while the galaxy's starburst ring coincides with a well-defined HI annulus delimited by a surface density of 3 Msun/pc^2. In stark contrast, the star-bursting companion, NGC 1510, has its young stellar population precisely matched to the highest HI over-densities we measure (~12.5 Msun/pc^2). The improved quality of the MeerKAT data warrants the first detailed measurements of the lengths and masses of the system's tidally-induced HI arms. We measure the longest of the two prominent HI arms to extend over ~27 kpc and to contain more than 30% of the system's total HI mass. We quantitatively explore the spatial correlation between HI and far-ultraviolet flux over a large range of HI mass surface densities spanning the outer disk. The results indicate the system's HI content to play an important role in setting the pre-conditions required for wide-spread, high-mass star formation. This work serves as a demonstration of the remarkable efficiency and accuracy with which MeerKAT can image nearby systems in HI line emission.Comment: 12 pages, 11 figures. Submitted only to arXi

Microscopic and Macroscopic Signatures of Antiferromagnetic Domain Walls

Magnetotransport measurements on small single crystals of Cr, the elemental antiferromagnet, reveal the hysteretic thermodynamics of the domain structure. The temperature dependence of the transport coefficients is directly correlated with the real-space evolution of the domain configuration as recorded by x-ray microprobe imaging, revealing the effect of antiferromagnetic domain walls on electron transport. A single antiferromagnetic domain wall interface resistance is deduced to be of order $5\times10^{-5}\mathrm{\mu\Omega\cdot cm^{2}}$ at a temperature of 100 K.Comment: 3 color figure

Group Chase and Escape

We describe here a new concept of one group chasing another, called "group chase and escape", by presenting a simple model. We will show that even a simple model can demonstrate rather rich and complex behavior. In particular, there are cases in which an optimal number of chasers exists for a given number of escapees (or targets) to minimize the cost of catching all targets. We have also found an indication of self-organized spatial structures formed by both groups.Comment: 13 pages, 12 figures, accepted and to appear in New Journal of Physic

The SHOW RESPECT adaptable framework of considerations for planning how to share trial results with participants, based on qualitative findings from trial participants and site staff

We are very thankful to the people who participated in this study and the women who contributed to our patient and public involvement activities. We are very grateful for the work of the Show RESPECT site teams in carrying out this study. We thank the members of the Show RESPECT study management group and steering group who are not authors on this manuscript: Andrew Copas, Cara Purvis, Nalinie Joharatnam-Hogan, Carlos Diaz-Montana, Archie Macnair, William J. Cragg and Conor Tweed. We thank the ICON8 trial team for their support of this project, particularly Andrew Clamp, Babasola Popoola, Francesca Schiavone, Jonathan Badrock and Rick Kaplan. We also thank the CHAPAS-4 trial team for allowing us to use CHAPAS-4 as an illustration of the application of our framework.Peer reviewe

Identification of Non-unitary triplet pairing in a heavy Fermion superconductor UPt_3

A NMR experiment recently done by Tou et al. on a heavy Fermion superconductor UPt$_3$ is interpreted in terms of a non-unitary spin-triplet pairing state which we have been advocating. The proposed state successfully explains various aspects of the seemingly complicated Knight shift behaviors probed for major orientations, including a remarkable d-vector rotation under weak fields. This entitles UPt$_3$ as the first example that a charged many body system forms a spin-triplet odd-par ity pairing at low temperatures and demonstrates unambiguously that the putative spin-orbit coupling in UPt$_3$ is weak.Comment: 4 pages, 2 eps figures, to be published in J. Phys. Soc. Jpn. 67 (1998) No.

Energy dispersive x-ray diffraction of charge density waves via chemical filtering

Pressure tuning of phase transitions is a powerful tool in condensed matter physics, permitting high-resolution studies while preserving fundamental symmetries. At the highest pressures, energy dispersive x-ray diffraction (EDXD) has been a critical method for geometrically confined diamond anvil cell experiments. We develop a chemical filter technique complementary to EDXD that permits the study of satellite peaks as weak as 10^(-4) of the crystal Bragg diffraction. In particular, we map out the temperature dependence of the incommensurate charge density wave diffraction from single-crystal, elemental chromium. This technique provides the potential for future GPa pressure studies of many-body effects in a broad range of solid state systems

Quantum skyrmions and the destruction of long-range antiferromagnetic order in the high-Tc superconductors La(2-x)Sr(x)CuO(4) and YBa(2)Cu(3)O(6+x)

We study the destruction of the antiferromagnetic order in the high-Tc superconductors La(2-x)Sr(x)CuO(4) and YBa(2)Cu(3)O(6+x) in the framework of the CP1-nonlinear sigma model formulation of the 2D quantum Heisenberg antiferromagnet. The dopants are introduced as independent fermions with appropriate dispersion relations determined by the shape of the Fermi surface. The energy of skyrmion topological defects, which are shown to be introduced by doping, is used as an order parameter for antiferromagnetic order. We obtain analytic expressions for this as a function of doping which allow us to plot the curves T_N(x_c)\times x_c and M(x)\times x, for both YBCO and LSCO, in good quantitative agreement with the experimental data.Comment: 4 pages, revtex, 5 embeeded figure

Cluster Dynamical Mean-field calculations for TiOCl

Based on a combination of cluster dynamical mean field theory (DMFT) and density functional calculations, we calculated the angle-integrated spectral density in the layered $s=1/2$ quantum magnet TiOCl. The agreement with recent photoemission and oxygen K-edge X-ray absorption spectroscopy experiments is found to be good. Th e improvement achieved with this calculation with respect to previous single-site DMFT calculations is an indication of the correlated nature and low-dimensionality of TiOCl.Comment: 9 pages, 3 figures, improved version as publishe

Analysis of Fcγ receptor haplotypes in rheumatoid arthritis: FCGR3A remains a major susceptibility gene at this locus, with an additional contribution from FCGR3B

The Fcγ receptors play important roles in the initiation and regulation of many immunological and inflammatory processes, and genetic variants (FCGR) have been associated with numerous autoimmune and infectious diseases. The data in rheumatoid arthritis (RA) are conflicting and we previously demonstrated an association between FCGR3A and RA. In view of the close molecular proximity with FCGR2A, FCGR2B and FCGR3B, additional polymorphisms within these genes and FCGR haplotypes were examined to refine the extent of association with RA. Biallelic polymorphisms in FCGR2A, FCGR2B and FCGR3B were examined for association with RA in two well characterized UK Caucasian and North Indian/Pakistani cohorts, in which FCGR3A genotyping had previously been undertaken. Haplotype frequencies and linkage disequilibrium were estimated across the FCGR locus and a model-free analysis was performed to determine association with RA. This was followed by regression analysis, allowing for phase uncertainty, to identify the particular haplotype(s) that influences disease risk. Our results reveal that FCGR2A, FCGR2B and FCGR3B were not associated with RA. The haplotype with the strongest association with RA susceptibility was the FCGR3A–FCGR3B 158V-NA2 haplotype (odds ratio 3.18, 95% confidence interval 1.13–8.92 [P = 0.03] for homozygotes compared with all genotypes). The association was stronger in the presence of nodules (odds ratio 5.03, 95% confidence interval 1.44–17.56; P = 0.01). This haplotype was also more common in North Indian/Pakistani RA patients than in control individuals, but not significantly so. Logistic regression analyses suggested that FCGR3A remained the most significant gene at this locus. The increased association with an FCGR3A–FCGR3B haplotype suggests that other polymorphic variants within FCGR3A or FCGR3B, or in linkage disequilibrium with this haplotype, may additionally contribute to disease pathogenesis