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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.
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.
To assess relationships between mothers’ feeding practices (food as a reward, food for emotion regulation, modelling of healthy eating) and mothers’ willingness to purchase child-marketed foods and fruits/vegetables (F&V) requested by their children during grocery co-shopping.
Cross-sectional. Mothers completed an online survey that included questions about feeding practices and willingness (i.e. intentions) to purchase child-requested foods during grocery co-shopping. Feeding practices scores were dichotomized at the median. Foods were grouped as nutrient-poor or nutrient-dense (F&V) based on national nutrition guidelines. Regression models compared mothers with above-the-median v. at-or-below-the-median feeding practices scores on their willingness to purchase child-requested food groupings, adjusting for demographic covariates.
Participants completed an online survey generated at a public university in the USA.
Mothers (n 318) of 2- to 7-year-old children.
Mothers who scored above-the-median on using food as a reward were more willing to purchase nutrient-poor foods (β=0·60, P<0·0001), mothers who scored above-the-median on use of food for emotion regulation were more willing to purchase nutrient-poor foods (β=0·29, P<0·0031) and mothers who scored above-the-median on modelling of healthy eating were more willing to purchase nutrient-dense foods (β=0·22, P<0·001) than were mothers with at-or-below-the-median scores, adjusting for demographic covariates.
Mothers who reported using food to control children’s behaviour were more willing to purchase child-requested, nutrient-poor foods. Parental feeding practices may facilitate or limit children’s foods requested in grocery stores. Parent–child food consumer behaviours should be investigated as a route that may contribute to children’s eating patterns.
Most dynamic ice-sheet studies currently use either empirically based
parameterizations or simple energy-balance climate models for the surface
mass-balance forcing. If three-dimensional global climate models (GCMs)
could be used instead, they would greatly improve the potential realism of
coupled climate ice-sheet simulations. However, there are two serious
problems in simulating realistic mass balances on ice sheets from GCM
simulations: (i) dynamic ice-sheet models and the underlying bedrock
topography need horizontal resolution of 50–100 km or less, but the finest
practical resolution of atmospheric GCMs is currently ˜250 km, and (ii) GCM
surface physics usually neglects the local refreezing of meltwater on ice
Two techniques are described that address these problems: an elevation
correction applied to the atmospheric GCM fields interpolated to the
ice-sheet grid, and a refreezing correction involving the annual totals of
snowfall, rainfall and local melt at each grid-point. As an example of their
use, we have used the GENESIS version 2 GCM at 3.75° × 3.75° resolution to
simulate the climate at the end of the last interglaciation at ˜116 000
years ago. The atmospheric climate is then used to drive a standard
two-dimensional dynamic ice-sheet model for 10 000 years on a 0.5° × 0.5°
grid spanning northern North America. The model successfully predicts
ice-sheet initiation over the Baffin Island highlands and the Canadian
Archipelago, but at a slower rate than observed. A large ice sheet nucleates
and grows rapidly over the northwestern Rockies, in conflict with geologic
evidence. Possible reasons for these discrepancies are discussed.
Asynchronous coupling schemes between ice sheet and atmospheric forcing models are evaluated for use in long-term ice-age simulations. In these schemes the ice sheet and atmospheric forcing are run together for short synchronous periods (Ts), alternating with longer asynchronous periods (TA) during which the ice sheet is run with atmospheric information extrapolated from the previous synchronous period(s). Two simple ice-sheet models are used that predict ice thickness as a function of latitude, and the atmosphere is represented by a prescribed pattern of net annual accumulation minus ablation. The pattern is shifted vertically to represent long-term orbital variations, stochastic inter-annual weather variability and ice-sheet albedo feedback.
Several asynchronous schemes are evaluated by comparing results with those from fully synchronous runs. The best overall results are obtained using a scheme in which the forcing during each asynchronous period is linearly extrapolated from its means in the previous two synchronous periods. Differences from the synchronous results are caused primarily by poor sampling of the stochastic forcing component, which exaggerates the stochastic ice-sheet fluctuations. We examine how these errors depend on Ts and TA, and outline implications for GCM ice-age simulations.
Some features around the perimeter of the Balgesvarri plateau ice cap are described. Sorted stone circles were found beneath a slowly retreating ice margin, the basal ice in this area appears to be below the pressure-melting point. No absolute dating of features was possible but a relative chronology is suggested.
We present infrared interferometric angular size measurements for rapidly rotating stars which indicate non-circular projected disk brightness distributions. For the A7IV-V star Altair, assuming that the apparent oblateness of the photosphere is due to the star's rapid rotation, a rigorous evaluation of the observation data in the context of a rigidly rotating Roche model shows that an estimate of v sin i = 210 ± 13 km s–1 can be derived that is independent of spectroscopic techniques. Altair is the first main sequence star for which direct observations of an oblate photosphere have been reported, and the first star for which v sin i has been established from observations of the star's photospheric geometry. Future prospects for this technique are considered, and a prospective catalog of 67 rotationally oblate targets is presented.
We present an overview of the survey for radio emission from active stars that has been in progress for the last six years using the observatories at Fleurs, Molonglo, Parkes and Tidbinbilla. The role of complementary optical observations at the Anglo-Australian Observatory, Mount Burnett, Mount Stromlo and Siding Spring Observatories and Mount Tamborine are also outlined. We describe the different types of star that have been included in our survey and discuss some of the problems in making the radio observations.