Some convergence results on the method of gradients for Ax=λBx

The method of gradients is a recently developed iterative technique for the solution of the generalized eigenvalue problem Ax=λBx. This paper essentially determines the size of the neighborhoods about the unit vectors in each eigenspace in which choices of initial estimates guarantee convergence of the iteration to the appropriate eigenvector

Evaluation of functions on microcomputers: rational approximation of kth roots

AbstractThis paper describes the implementation of rational approximation algorithms for evaluation of kth roots in short wordlength machines. The emphasis is on maintaining full machine precision in computers that use fixed point, truncated binary arithmetic with at most 16 bits of wordlength. Included is a table of coefficients for evaluation of kth roots on a 16 bit machine with 3 ≤ k ≤ 11

Effect of selective removal of badgers (Meles meles) on ranging behaviour during a ‘Test and Vaccinate or Remove’ intervention in Northern Ireland

Publication history: Accepted - 23 April 2021; Published online - 7 May 2021The role of the Eurasian badger (Meles meles) as a wildlife host has complicated the management of bovine tuberculosis (bTB) in cattle. Badger ranging behaviour has previously been found to be altered by culling of badgers and has been suggested to increase the transmission of bTB either among badgers or between badgers and cattle. In 2014, a five-year bTB intervention research project in a 100 km2 area in Northern Ireland was initiated involving selective removal of dual path platform (DPP) VetTB (immunoassay) test positive badgers and vaccination followed by release of DPP test negative badgers (‘Test and Vaccinate or Remove’). Home range sizes, based on position data obtained from global positioning system collared badgers, were compared between the first year of the project, where no DPP test positive badgers were removed, and follow-up years 2–4 when DPP test positive badgers were removed. A total of 105 individual badgers were followed over 21 200 collar tracking nights. Using multivariable analyses, neither annual nor monthly home ranges differed significantly in size between years, suggesting they were not significantly altered by the bTB intervention that was applied in the study area.This research was funded by the Department of Agriculture, Environment and Rural Affairs for Northern Ireland

Velocity-space sensitivity of the time-of-flight neutron spectrometer at JET

The velocity-space sensitivities of fast-ion diagnostics are often described by so-called weight functions. Recently, we formulated weight functions showing the velocity-space sensitivity of the often dominant beam-target part of neutron energy spectra. These weight functions for neutron emission spectrometry (NES) are independent of the particular NES diagnostic. Here we apply these NES weight functions to the time-of-flight spectrometer TOFOR at JET. By taking the instrumental response function of TOFOR into account, we calculate time-of-flight NES weight functions that enable us to directly determine the velocity-space sensitivity of a given part of a measured time-of-flight spectrum from TOFOR

Relationship of edge localized mode burst times with divertor flux loop signal phase in JET

A phase relationship is identified between sequential edge localized modes (ELMs) occurrence times in a set of H-mode tokamak plasmas to the voltage measured in full flux azimuthal loops in the divertor region. We focus on plasmas in the Joint European Torus where a steady H-mode is sustained over several seconds, during which ELMs are observed in the Be II emission at the divertor. The ELMs analysed arise from intrinsic ELMing, in that there is no deliberate intent to control the ELMing process by external means. We use ELM timings derived from the Be II signal to perform direct time domain analysis of the full flux loop VLD2 and VLD3 signals, which provide a high cadence global measurement proportional to the voltage induced by changes in poloidal magnetic flux. Specifically, we examine how the time interval between pairs of successive ELMs is linked to the time-evolving phase of the full flux loop signals. Each ELM produces a clear early pulse in the full flux loop signals, whose peak time is used to condition our analysis. The arrival time of the following ELM, relative to this pulse, is found to fall into one of two categories: (i) prompt ELMs, which are directly paced by the initial response seen in the flux loop signals; and (ii) all other ELMs, which occur after the initial response of the full flux loop signals has decayed in amplitude. The times at which ELMs in category (ii) occur, relative to the first ELM of the pair, are clustered at times when the instantaneous phase of the full flux loop signal is close to its value at the time of the first ELM

New insights into the genetic etiology of Alzheimer's disease and related dementias

Characterization of the genetic landscape of Alzheimer's disease (AD) and related dementias (ADD) provides a unique opportunity for a better understanding of the associated pathophysiological processes. We performed a two-stage genome-wide association study totaling 111,326 clinically diagnosed/'proxy' AD cases and 677,663 controls. We found 75 risk loci, of which 42 were new at the time of analysis. Pathway enrichment analyses confirmed the involvement of amyloid/tau pathways and highlighted microglia implication. Gene prioritization in the new loci identified 31 genes that were suggestive of new genetically associated processes, including the tumor necrosis factor alpha pathway through the linear ubiquitin chain assembly complex. We also built a new genetic risk score associated with the risk of future AD/dementia or progression from mild cognitive impairment to AD/dementia. The improvement in prediction led to a 1.6- to 1.9-fold increase in AD risk from the lowest to the highest decile, in addition to effects of age and the APOE ε4 allele

Information management focus and operations : delivery plan 2010-2011 and beyond

This report provides an overview of the work undertaken by the Information Management Focus and Operations Team for the financial year 2010-11 and includes a forward look for future years. Currently the Team’s projects cover specialist data management activities under five geoscience themes, geophysics, geology, hydrogeology, geochemistry and marine plus a multi tasked project covering corporate metadata, proactive data verification and project data storage. The Geo-Seas project, a Pan-European e-infrastructure project for the management of marine geological and geophysical data, is also managed under this Team

Information management focus and operations : delivery plan 2011-2012 and beyond

This report provides an overview of the work undertaken by the Information Management Focus and Operations Team for the financial year 2011-12 and includes a forward look for future years. Currently the Team’s projects cover specialist data management activities under five geoscience themes, geophysics, geology, hydrogeology, geochemistry and marine plus a multi tasked project covering corporate metadata, proactive data verification and project data management. The Geo- Seas project, a Pan-European e-infrastructure project for the management of marine geological and geophysical data, is also managed under this Team

Simultaneous rayleigh-quotient minimization methods for Ax=λBx

AbstractNew simultaneous iteration techniques are developed for solving the generalized eigenproblem Ax=λBx, where A and B are real symmetric matrices and B is positive definite. The approach is to minimize the generalized Rayleigh quotient in some sense over several independent vectors simultaneously. In particular, each new vector iterate is formed from a linear combination of current iterates and correction vectors that are derived from either gradient or conjugate-gradient techniques. A Ritz projection or simultaneous iteration process is used to accelerate convergence. For one of the gradient versions, convergence and asymptotic rates of convergence are established. Also, some numerical experiments are reported that demonstrate the convergence behavior of these methods