5,918 research outputs found
The dynamics and excitation of torsional waves in geodynamo simulations
The predominant force balance in rapidly rotating planetary cores is between Coriolis, pressure, buoyancy and Lorentz forces. This magnetostrophic balance leads to a Taylor state where the spatially averaged azimuthal Lorentz force is compelled to vanish on cylinders aligned with the rotation axis. Any deviation from this state leads to a torsional oscillation, signatures of which have been observed in the Earth's secular variation and are thought to influence length of day variations via angular momentum conservation. In order to investigate the dynamics of torsional oscillations (TOs), we perform several 3-D dynamo simulations in a spherical shell. We find TOs, identified by their propagation at the correct AlfvĂ©n speed, in many of our simulations. We find that the frequency, location and direction of propagation of the waves are influenced by the choice of parameters. Torsional waves are observed within the tangent cylinder and also have the ability to pass through it. Several of our simulations display waves with core traveltimes of 4â6âyr. We calculate the driving terms for these waves and find that both the Reynolds force and ageostrophic convection acting through the Lorentz force are important in driving TOs
Short-term Response of Holcus lanatus L. (Common Velvetgrass) to Chemical and Manual Control at Yosemite National Park, USA
One of the highest priority invasive species at both Yosemite and Sequoia and Kings Canyon national parks is Holcus lanatus L. (common velvetgrass), a perennial bunchgrass that invades mid-elevation montane meadows. Despite velvetgrass being a high priority species, there is little information available on control techniques. The goal of this project was to evaluate the short-term response of a single application of common chemical and manual velvetgrass control techniques. The study was conducted at three montane sites in Yosemite National Park. Glyphosate spotspray treatments were applied at 0.5, 1.0, 1.5, and 2.0% concentrations, and compared with hand pulling to evaluate effects on cover of common velvetgrass, cover of other plant species, and community species richness. Posttreatment year 1 cover of common velvetgrass was 12.1% 6 1.6 in control plots, 6.3% 6 1.5 averaged over the four chemical treatments (all chemical treatments performed similarly), and 13.6% 6 1.7 for handpulled plots. This represents an approximately 50% reduction in common velvetgrass cover in chemically- treated plots recoded posttreatment year 1 and no statistically significant reduction in hand pulled plots compared with controls. However, there was no treatment effect in posttreatment year 2, and all herbicide application rates performed similarly. In addition, there were no significant treatment effects on nontarget species or species richness. These results suggest that for this level of infestation and habitat type, (1) one year of hand pulling is not an effective control method and (2) glyphosate provides some level of control in the short-term without impact to nontarget plant species, but the effect is temporary as a single year of glyphosate treatment is ineffective over a twoyear period
A response to the House of Commons Education Committee report on Multi-Academy Trusts
The number of schools joining multi-academy trusts has grown over the last five years, and it is expected that this growth will continue. The House of Commons Education Committee has, as a result, looked into the performance and role of these trusts. Steven J Courtney, Ruth McGinity, Steven Jones, Robert Hindle, Stephen M Rayner and Belinda Hughes focus on four key aspects of the Committeeâs report and argue that broader questions about the governmentâs policy remain untouched
Perturbation of Interaction Networks for Application to Cancer Therapy
We present a computational approach for studying the effect of potential drug combinations on the protein networks associated with tumor cells. The majority of therapeutics are designed to target single proteins, yet most diseased states are characterized by a combination of many interacting genes and proteins. Using the topology of protein-protein interaction networks, our methods can explicitly model the possible synergistic effect of targeting multiple proteins using drug combinations in different cancer types
Linear and nonlinear properties of the Goldreich-Schubert-Fricke instability in stellar interiors with arbitrary local radial and latitudinal differential rotation
We investigate the linear and nonlinear properties of the
Goldreich-Schubert-Fricke (GSF) instability in stellar radiative zones with
arbitrary local (radial and latitudinal) differential rotation. This
instability may lead to turbulence that contributes to redistribution of
angular momentum and chemical composition in stars. In our local Boussinesq
model, we investigate varying the orientation of the shear with respect to the
'effective gravity', which we describe using the angle . We first perform
an axisymmetric linear analysis to explore the effects of varying on the
local stability of arbitrary differential rotations. We then explore the
nonlinear hydrodynamical evolution in three dimensions using a modified
shearing box. The model exhibits both the diffusive GSF instability, and a
non-diffusive instability that occurs when the Solberg-H\{o}iland criteria are
violated. We observe the nonlinear development of strong zonal jets ("layering"
in the angular momentum) with a preferred orientation in both cases, which can
considerably enhance turbulent transport. By varying we find the
instability with mixed radial and latitudinal shears transports angular
momentum more efficiently (particularly if adiabatically unstable) than cases
with purely radial shear . By exploring the dependence on box size,
we find the transport properties of the GSF instability to be largely
insensitive to this, implying we can meaningfully extrapolate our results to
stars. However, there is no preferred length-scale for adiabatic instability,
which therefore exhibits strong box-size dependence. These instabilities may
contribute to the missing angular momentum transport required in red giant and
subgiant stars and drive turbulence in the solar tachocline.Comment: 26 pages, 17 figures, 4 tables, accepted for publication in MNRAS
(28th June 2023
Depression and anxiety symptoms at TNF inhibitor initiation are associated with impaired treatment response in axial spondyloarthritis
Acknowledgment We are grateful to Professor Gary Macfarlane for commenting on the manuscript. We are grateful to the staff of the BSRBR-AS register and to the recruiting staff at the clinical centres, details of which are available at: www.abdn.ac.uk/bsrbr-as. We also thank Dr Lewis Carpenter for suggesting splines for modelling time. Contribution: SSZ analysed the data and wrote the manuscript with significant input from all co- authors. GTJ is the Deputy Chief Investigator on BSRBR-AS and designed the study and oversaw its conduct. In the current project they discussed results and provided input into drafts of the manuscript. Funding: The BSRBR-AS is funded by the British Society for Rheumatology (BSR) who have received funding for this from Pfizer, AbbVie and UCB. These companies receive advance copies of manuscripts for comments. They have no input in determining the topics for analysis or work involved in undertaking it.Peer reviewedPublisher PD
- âŠ