Investigation of ground vibration from circular tunnels using a 2.5D FE/BE model of tunnel and ground

A numerical model of a circular tunnel using the 2.5D finite element and boundary element method is described. This makes use of the constant geometry in the axial direction so that a two-dimensional model is solved for a series of wavenumbers. The full 3D solution can be recovered by a Fourier transformation. The response of the tunnel structure is analysed first. Then, the vibration at certain points on the ground surface is predicted using the tunnel-soil model. Finally, a parametric study is carried out to show the influence of different aspects of tunnel design to the vibration in the ground

Surface state reconstruction in ion-damaged SmB_6

We have used ion-irradiation to damage the (001) surfaces of SmB_6 single crystals to varying depths, and have measured the resistivity as a function of temperature for each depth of damage. We observe a reduction in the residual resistivity with increasing depth of damage. Our data are consistent with a model in which the surface state is not destroyed by the ion-irradiation, but instead the damaged layer is poorly conducting and the initial surface state is reconstructed below the damage. This behavior is consistent with a surface state that is topologically protected.Comment: 5 pages, 3 figure

Effective Field Theory for Rydberg Polaritons

We develop an effective field theory (EFT) to describe the few- and many-body propagation of one dimensional Rydberg polaritons. We show that the photonic transmission through the Rydberg medium can be found by mapping the propagation problem to a non-equilibrium quench, where the role of time and space are reversed. We include effective range corrections in the EFT and show that they dominate the dynamics near scattering resonances in the presence of deep bound states. Finally, we show how the long-range nature of the Rydberg-Rydberg interactions induces strong effective $N$-body interactions between Rydberg polaritons. These results pave the way towards studying non-perturbative effects in quantum field theories using Rydberg polaritons.Comment: 5+ pages main text, 3 figures; 5 pages supplemental, 1 figure; v2 - replaced discussion of N-body bound state preparation with discussion of effective range corrections and made other minor correction

Superconductivity in Mg10Ir19B16

Mg10Ir19B16, a previously unreported compound in the Mg-Ir-B chemical system, is found to be superconducting at temperatures near 5 K. The fact that the compound exhibits a range of superconducting temperatures between 4 and 5 K suggests that a range of stoichiometries is allowed, though no structural evidence for this is observed. The compound has a large, noncentrosymmetric, body centered cubic unit cell with a = 10.568 Angstrom, displaying a structure type for which no previous superconductors have been reported.Comment: submitted to PR

The Role of an Urban Tallgrass Prairie Remnant in Conservation: A Case Study in Central Iowa (USA)

Although more than 85% of Iowa (USA) was covered by tallgrass prairie at the time of settlement by Europeans in the early 19th century, less than 0.1% remains. The Richard W. Pohl State Preserve at Ames (IA) High School, surrounded on three sides by structures, roads, and other development, protects 4 ha of tallgrass prairie. The preserve, commonly referred to as Ames High Prairie (AHP), was grazed but never plowed under private ownership until its acquisition by the Ames School District in 1959. Although considered for development as a parking lot or football field in the 1960s, the residents of Ames voted in 1970 to award The Nature Conservancy (TNC) a 49-year lease to the property (until 2019). This preserve, almost completely open in the 1930s, has been subject to numerous threats, including encroachment by woody plants, entry of non-native and invasive plant species associated with human activity, and erosion associated with storm water runoff, sewer line repair, foot and bike traffic, and major flood events. Recent management activities at AHP, conducted by volunteer land stewards, high school and college students, TNC summer interns, and private contractors, has consisted of controlled burns, cutting and herbicide treatment of encroaching woody plants, manual removal and herbicide treatment of invasive herbaceous plants, and sowing of seeds (collected on site) into reopened areas. Three vascular plant inventories of the 8.9 ha preserve (1966, 1995, current study) have documented the occurrence of 465 taxa (329 native) at AHP, including 5 Iowa special concern species. This flora includes 147 native prairie plant taxa, which ranks 8th in comparison with the 26 other (and mostly larger) prairies protected as state preserves in Iowa. As a vegetation remnant, AHP protects tallgrass prairie taxa and their gene pools, maintains an example of historically abundant (but now scarce) tallgrass prairie vegetation, and provides citizens an opportunity to experience prairie

Magnetocrystalline anisotropic effect in GdCo1−x_{1-x}Fex_xAsO (x=0,0.05x = 0, 0.05)

From a systematic study of the electrical resistivity $\rho(T,H)$, magnetic susceptibility $\chi(T,H)$, isothermal magnetization $M(H)$ and the specific heat $C(T,H)$, a temperature-magnetic field ($T$-$H$) phase diagram has been established for GdCo$_{1-x}$Fe$_x$AsO ($x = 0$ and $0.05$) polycrystalline compounds. GdCoAsO undergoes two long-range magnetic transitions: ferromagnetic (FM) transition of Co $3d$ electrons ($T_\textup{C}^\textup{Co}$) and antiferromagnetic (AFM) transition of Gd $4f$ electrons ($T_\textup{N}^\textup{Gd}$). For the Fe-doped sample ($x=0.05$), an extra magnetic reorientation transition takes place below $T_\textup{N}^\textup{Gd}$, which is likely associated with Co moments. The two magnetic species of Gd and Co are coupled antiferromagnetically to give rise to ferrimagnetic (FIM) behavior in the magnetic susceptibility. Upon decreasing the temperature ($T < T_\textup{C}^\textup{Co}$), the magnetocrystalline anisotropy breaks up the FM order of Co by aligning the moments with the local easy axes of the various grains, leading to a spin reorientation transition at $T_\textup{R}^\textup{Co}$. By applying a magnetic field, $T_\textup{R}^\textup{Co}$ monotonically decreases to lower temperatures, while the $T_\textup{N}^\textup{Gd}$ is relatively robust against the external field. On the other hand, the applied magnetic field pulls the magnetization of grains from the local easy direction to the field direction via a first-order reorientation transition, with the transition field ($H_\textup{M}$) increasing upon cooling the temperature.Comment: accepted by physical Review B 6 figures and 7 page

Physiology and Pathophysiology of the Swallowing Area of Human Motor Cortex

Swallowing problems can affect as many as one in three patients in the period immediately after stroke. Despite this, in the majority of cases, recovery usually occurs to a safe level after a month or two. In this review, we show. how the organization of the cortical projections to swallowing nuscles can account for many of the clinical observations on swallowing after stroke and explain why recovery is common in the long term. In addition, we examine approaches that may be useful in speeding up recovery of swallowing. Swallowing may be a useful model in which to study central nervous reorganization after injury