The angular dependence of spin-orbit torque in monolayer Fe3GeTe2Fe_3GeTe_2

In ferromagnetic systems lacking inversion symmetry, an applied electric field can control the ferromagnetic order parameters through the spin-orbit torque. The prototypical example is a bilayer heterostructure composed of a ferromagnet and a heavy metal that acts as a spin current source. In addition to such bilayers, spin-orbit coupling can mediate spin-orbit torques in ferromagnets that lack bulk inversion symmetry. A recently discovered example is the two-dimensional monolayer ferromagnet $Fe_3GeTe_2$. In this work, we use first-principles calculations to study the spin-orbit torque and ensuing magnetic dynamics in this material. By expanding the torque versus magnetization direction as a series of vector spherical harmonics, we find that higher order terms (up to $\ell=4$) are significant and play important roles in the magnetic dynamics. They give rise to deterministic, magnetic field-free electrical switching of perpendicular magnetization.Comment: 8 pages (3 pages appendix), 7 figure

Historic Timber-built Seacoast Piers of Eastern England: Technological, Environmental and Social Contexts

The aim of this thesis is to initially establish the existence of a class of monument, the timber-built seacoast pier, which has heretofore received virtually no investigation by archaeologists and been merely briefly referred to by a handful of historians. Data sources for this topic are diverse and include documentary sources, material remains, cartographic and pictorial evidence, coastal geomorphology and place-names. Investigation is perforce multi-disciplinary. This study will show that such structures were once quite widespread within the study area of eastern England, and indeed further afield. These structures were far from identical and the varying technical forms of the piers are determined and explanations sought to account for these. The physical backdrop to these piers was the varied and dynamic coastal environment of the eastern seaboard of the North Sea and it is not possible to gain a broad understanding of the piers without reference to this environment. Timber-built seacoast piers required enormous resources to construct. They were regularly subject to damage and destruction and they were costly to maintain. Given such circumstances, communities often struggled to maintain their piers. Occasionally, their resources expended, this battle was lost. More often they limped on, saved by appeal to the wider community, county or crown. The lengths to which communities were prepared to go in order to safeguard their piers demonstrates the enormous value attached to them by the communities and bodies to whom they belonged. Piers came to be important items of infrastructure that were essential to the well being of many local economies and in the meshing together of these with wider economies, regional, national and international. Whilst the technology of seacoast piers is of some intrinsic interest, perhaps the greatest potential of this topic lies in the social and economic spheres

Application of Dynamic pressure-balanced Seals in a Multi-stage Centrifugal Compressor

LecturesTest results for an ASME Power Test Code 10 (PTC) Type 1 test of a 4,500 psia (310 Bara) discharge pressure gas lift centrifugal compressor outfitted with dynamic pressure-balanced seals at the impeller eyes; shaft interstage and division wall locations are presented and compared to the same testing with conventional labyrinth seals. Both aerodynamic performance and rotor dynamic stability, obtained via operational modal analysis (OMA), are presented. A client’s motivation, along with the design and testing of dynamic pressure-balanced (DPB) seals for turbomachinery are also presented in this paper. With the DPB seals installed the test results indicate 2.8 percent lower power was required for the same head level across the entire range of inlet flows and pressure ratios, when compared to the same testing with conventional labyrinth seals. Rotordynamic stability, obtained via operational modal analysis (OMA), showed the dynamic pressure-balanced (DPB) seals exhibited log decs similar to standard labyrinth seals across the entire range of flows and pressure ratios. The foregoing demonstrates both the aerodynamic and mechanical/rotordynamic integrity of the dynamic pressure-balanced seals for oil and gas, turbomachinery applications

Isoform-specific subcellular localization and function of protein kinase A identified by mosaic imaging of mouse brain.

Protein kinase A (PKA) plays critical roles in neuronal function that are mediated by different regulatory (R) subunits. Deficiency in either the RIβ or the RIIβ subunit results in distinct neuronal phenotypes. Although RIβ contributes to synaptic plasticity, it is the least studied isoform. Using isoform-specific antibodies, we generated high-resolution large-scale immunohistochemical mosaic images of mouse brain that provided global views of several brain regions, including the hippocampus and cerebellum. The isoforms concentrate in discrete brain regions, and we were able to zoom-in to show distinct patterns of subcellular localization. RIβ is enriched in dendrites and co-localizes with MAP2, whereas RIIβ is concentrated in axons. Using correlated light and electron microscopy, we confirmed the mitochondrial and nuclear localization of RIβ in cultured neurons. To show the functional significance of nuclear localization, we demonstrated that downregulation of RIβ, but not of RIIβ, decreased CREB phosphorylation. Our study reveals how PKA isoform specificity is defined by precise localization