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Presenting a field-defining overview of one of the most appliable linguistic theories available today, this Handbook surveys the key issues in the study of systemic functional linguistics (SFL), covering an impressive range of theoretical perspectives. Written by some of the world's foremost SFL scholars, including M. A. K. Halliday, the founder of SFL theory, the handbook covers topics ranging from the theory behind the model, discourse analysis within SFL, applied SFL, to SFL in relation to other subfields of linguistics such as intonation, typology, clinical linguistics and education. Chapters include discussion on the possible future directions in which research might be conducted and issues that can be further investigated and resolved. Readers will be inspired to pursue the challenges raised within the volume, both theoretically and practically.
The objective of this research was to evaluate producers’ perspectives of four key precision agriculture technologies (variable rate fertilizer application, precision soil sampling, guidance and autosteer, and yield monitoring) in terms of the benefits they provide to their farms (increased yield, reduced production costs, and increased convenience) using a best-worst scaling choice experiment. Results indicate that farmers’ perceptions of the benefits derived from various precision agriculture technologies are heterogeneous. To better understand farmers’ adoption decisions, or lack thereof, it is important to first understand their perceptions of the benefits precision agriculture technologies provide.
This paper studies the transition to three-dimensional flow in the wake of a cylinder immersed in a free stream, where the cylinder is externally forced to continuously rotate about its axis and to linearly oscillate in the streamwise direction. Floquet stability analysis is used to assess the stability of the nominal two-dimensional flows at a Reynolds number
and rotation rate
to three-dimensional perturbations, as a function of the amplitude and frequency of the linear oscillations. Two modes of instability are found, distinguished by their spatial structure, temporal behaviour and apparent mechanism. The first mode has a shorter wavelength in the spanwise direction and appears to be linked to a centrifugal instability in the layer of fluid near the rotating body. The second mode has a longer wavelength and is linked to an instability of the vortex cores in the wake that is subharmonic, leading to a period doubling. Either mode can be stable while the other is unstable, depending primarily on the frequency of the oscillation of the cylinder. This indicates that either mode can control the transition to a three-dimensional flow. The results are compared to the fully three-dimensional simulation results of a rotating cylinder elastically mounted and free to oscillate in the streamwise direction from Bourguet & Lo Jacono (J. Fluid Mech., vol. 781, 2015, pp. 127–165), and appear to be able to explain the surprising switching of the observed spanwise wavelength in that flow as a change in the dominant mode, and therefore mechanism, of instability.
At the Last Glacial Maximum (LGM) about 21000 years ago (21 ka BP), the
overall mass balance of the Laurentide and Eurasian ice sheets should have
been close to zero, since their rate of change of total ice volume was
approximately zero at that time. The surface mass balance should have been
zero or positive to balance any iceberg/iceshelf discharge and basal
melting, but could not have been strongly negative. In principle this can be
tested by global climate model (GCM) simulations with prescribed ice-sheet
extents and topography.
We describe results from a suite of 21 ka BP simulations using a new GCM
(GENESIS version 2.0.a), with sea-surface temperatures (SSTs) prescribed
from GLIMAP (1981) and predicted by a mixed-layer ocean model, and with ice
sheets prescribed from both the ICE-4G (Peltier, 1994) and CLIMAP (1981) reconstructions. This GCM is
well suited for ice-sheet mass-balance studies because (i) the surface can
be represented at a finer resolution than the atmospheric GCM, (ii) an
elevation correction accounts for spectral distortions of the atmospheric
GCM topography, (iii) a simple post-processing correction for the refreezing
of meltwater is applied, and (iv) the model's precipitation and mass
balances for present-day Greenland and Antarctica are realistic. However,
for all reasonable combinations of SSTs and ice-sheet configurations, the
predicted annual surface mass balances of the LGM Laurentide and Eurasian
ice sheets are implausibly negative. Possible reasons for this discrepancy
are discussed, including increased ice-age aerosols, higher CLIMAP-like
ice-sheet profiles in the few thousand years preceding the LGM, and a
surface of the southern Laurentide just before the LGM to produce fleetingly
the ICE-4G profile at 21 ka BP.
Many studies have identified changes in the brain associated with obsessive–compulsive disorder (OCD), but few have examined the relationship between genetic determinants of OCD and brain variation.
We present the first genome-wide investigation of overlapping genetic risk for OCD and genetic influences on subcortical brain structures.
Using single nucleotide polymorphism effect concordance analysis, we measured genetic overlap between the first genome-wide association study (GWAS) of OCD (1465 participants with OCD, 5557 controls) and recent GWASs of eight subcortical brain volumes (13 171 participants).
We found evidence of significant positive concordance between OCD risk variants and variants associated with greater nucleus accumbens and putamen volumes. When conditioning OCD risk variants on brain volume, variants influencing putamen, amygdala and thalamus volumes were associated with risk for OCD.
These results are consistent with current OCD neurocircuitry models. Further evidence will clarify the relationship between putamen volume and OCD risk, and the roles of the detected variants in this disorder.
Declaration of interest
The authors have declared that no competing interests exist.