Teaching grammar: Rethinking the approach

In this article Margaret Kettle examines grammar, its image problem and some new developments aimed at improving its teaching and learning in the TESOL classroom

B-meson decay constants: a more complete picture from full lattice QCD

We extend the picture of $B$-meson decay constants obtained in lattice QCD beyond those of the $B$, $B_s$ and $B_c$ to give the first full lattice QCD results for the $B^*$, $B^*_s$ and $B^*_c$. We use improved NonRelativistic QCD for the valence $b$ quark and the Highly Improved Staggered Quark (HISQ) action for the lighter quarks on gluon field configurations that include the effect of $u/d$, $s$ and $c$ quarks in the sea with $u/d$ quark masses going down to physical values. For the ratio of vector to pseudoscalar decay constants, we find $f_{B^*}/f_B$ = 0.941(26), $f_{B^*_s}/f_{B_s}$ = 0.953(23) (both $2\sigma$ less than 1.0) and $f_{B^*_c}/f_{B_c}$ = 0.988(27). Taking correlated uncertainties into account we see clear indications that the ratio increases as the mass of the lighter quark increases. We compare our results to those using the HISQ formalism for all quarks and find good agreement both on decay constant values when the heaviest quark is a $b$ and on the dependence on the mass of the heaviest quark in the region of the $b$. Finally, we give an overview plot of decay constants for gold-plated mesons, the most complete picture of these hadronic parameters to date.Comment: 20 pages, 9 figures. Minor updates to the discussion in several places and some additional reference

Groundwater Depletion and Agricultural Land Use Change in Wichita County, Kansas

Though researchers have documented groundwater and land use changes in the High Plains, few studies have investigated their interactions. This paper examines the relationship between groundwater depletion and agricultural land use change in greater detail than previous studies. Water well measurements and satellite imagery were used to detect changes in groundwater and land cover in Wichita County, Kansas, between 1975 and 2001. Analysis of these changes using GIS indicated that areas experiencing the greatest decline in groundwater were indeed being removed from irrigation, while areas with limited groundwater decline were experiencing fewer land use changes

The contribution of linear perspective cues and texture gradients in the perceptual rescaling of stimuli inside a Ponzo illusion corridor

We examined the influence of linear perspective cues and texture gradients in the perceptual rescaling of stimuli over a highly-salient Ponzo illusion of a corridor. We performed two experiments using the Method of Constant Stimuli where participants judged the size of one of two rings. In experiment 1, one ring was presented in the upper visual-field at the end of the corridor and the other in the lower visual-field at the front of the corridor. The perceived size of the top and bottom rings changed as a function of the availability of linear perspective and textures. In experiment 2, only one ring was presented either at the top or the bottom of the image. The perceived size of the top but not the bottom ring changed as a function of the availability of linear perspective and textures. In both experiments, the effects of the cues were additive. Perceptual rescaling was also stronger for the top compared to the bottom ring. Additional eye-tracking revealed that participants tended to gaze more in the upper than the lower visual-field. These findings indicate that top-down mechanisms provide an important contribution to the Ponzo illusion. Nonetheless, additional maximum likelihood estimation analyses revealed that linear perspective fulfilled a greater contribution in experiment 2, which is suggestive of a bottom-up mechanism. We conclude that both top-down and bottom-up mechanisms play important roles. However, the former seems to fulfil a more prominent role when both stimuli are presented in the image

Dark Production: A Significant Source of Oceanic COS

Carbonyl sulfide (COS) in air and dissolved in seawater was determined during a cruise in August 1999 in the Sargasso Sea in the northwest Atlantic Ocean. Dissolved concentrations at the sea surface displayed only a weak diel cycle with a mean of 8.6 ± 2.8 pmol dm−3 owing to low abundance of photochemical precursors and high temperatures causing rapid hydrolysis. Depth profiles measured over the oceanic mixed layer revealed significant vertical gradients of COS concentration with higher values at the surface, suggesting that the rate of photochemical production at the surface exceeds the rate of vertical mixing. The mean atmospheric mixing ratio was 486 ± 40 ppt, and calculated sea-air fluxes ranged from 0.03 to 0.8 g COS km−2 d−1. COS dark production, estimated from the predawn COS concentration at the surface and the hydrolysis constant, contributed significantly to the total amount of COS produced. A strong temperature dependence of the COS dark production rate q was found by comparing previously published values. The data further indicate an approximately first-order relationship between q and chromophoric dissolved organic matter (CDOM) absorbance at 350 nm, a350, which is used as a proxy for the CDOM content of the water but is likely to covary with other parameters, such as biological activity, that could also affect COS dark production. Together with known functions for COS hydrolysis and solubility, the parameterization of dark production as a function of temperature and a350 allows for the prediction of COS concentrations and saturation ratios as a function of physical and optical seawater properties in the absence of photoproduction. This is used to estimate a lower limit of 0.056 Tg COS yr−1 to the annual COS flux from the ocean to the atmosphere

Report on R. V. Akademik Vernadsky cruise 39, stage IV, June 17 - July 17, 1989

Participation by U. S. personnel on Cruise 39, Leg IV (June 17 - July 17, 1989) of the Marine Hydrophysical Institute's research vessel Akademik Vernadsky provided valuable information, documented in the present report for planning future cooperative projects with Soviet oceanographers. Detailed descriptions are given of the ship, its scientific laboratories, computers and onboard instrumentation. Planning and operating procedures are described and examples are given of daily work plans, seminars, menus and social activities. Personal accounts by the U. S. participants are also included. Many of the shipboard activities were recorded on VHS video cassettes. The oceanographic data collected in the Gulf Stream survey region during Leg IV are documented in the report. Copies of data sets were provided to the U. S. participants in exchange for U. S. data from the region during the survey period.Funding was provided by Vetelsen, the Education Office of Woods Hole Oceanographic Institution, and a Dr. Willam B. Richardson Summer Fellowship provided by Alden Products Company

Light-driven cycling of dimethylsulfide (DMS) in the Sargasso Sea : closing the loop

Author Posting. © American Geophysical Union, 2004. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 31 (2004): L09308, doi:10.1029/2004GL019581.The factors driving dimethylsulfide (DMS) cycling in oligotrophic environments are isolated using a time-series of DMS sampled in the Sargasso Sea. The observed distribution of DMS is inconsistent with bottom-up processes related to phytoplankton production, biomass, or community structure changes. DMS concentrations and estimates of net biological community production are most highly correlated with physical and optical properties, with the dose of ultraviolet radiation (UVR) accounting for 77% of the variability in mixed layer DMS concentrations. Physiological stresses associated with shallow mixed layers and high UVR are the first order determinant of biological production of DMS, indicating that DMS cycling in open-ocean regions is fundamentally different than in eutrophic regions where phytoplankton blooms provide the conditions for elevated DMS concentrations. The stress regime presented here effectively closes the DMS-climate feedback loop for open-ocean environments. This response may also provide a climatic role for phytoplanktonic processes in response to anthropogenic forcing.This work was supported by a NASA Earth System Science Fellowship