Transgenic maize engineered to express insecticidal proteins from the bacterium Bacillus thuringiensis (Bt) has become widely adopted in U.S. agriculture. In 2009, Bt maize was planted on more than ...22.2 million hectares, constituting 63% of the U.S. crop. Using statistical analysis of per capita growth rate estimates, we found that areawide suppression of the primary pest Ostrinia nubilalis (European corn borer) is associated with Bt maize use. Cumulative benefits over 14 years are an estimated $3.2 billion for maize growers in Illinois, Minnesota, and Wisconsin, with more than $2.4 billion of this total accruing to non-Bt maize growers. Comparable estimates for Iowa and Nebraska are $3.6 billion in total, with $1.9 billion for non-Bt maize growers. These results affirm theoretical predictions of pest population suppression and highlight economic incentives for growers to maintain non-Bt maize refugia for sustainable insect resistance management.
The stomach is traditionally regarded as a hollow muscular sac that initiates the second phase of digestion. Yet this simple view ignores the fact that it is the most sophisticated endocrine organ ...with unique physiology, biochemistry, immunology and microbiology. All ingested materials, including our nutrition, have to negotiate this organ first, and as such, the stomach is arguably the most important segment within the GI tract. The unique biological function of gastric acid secretion not only initiates the digestive process but also acts as a first line of defence against food-borne microbes. Normal gastric physiology and morphology may be disrupted by Helicobacter pylori infection, the most common chronic bacterial infection in the world and the aetiological agent for most peptic ulcers and gastric cancer. In this state-of-the-art review, the most relevant new aspects of the stomach in health and disease are addressed. Topics include gastric physiology and the role of gastric dysmotility in dyspepsia and gastroparesis; the stomach in appetite control and obesity; there is an update on the immunology of the stomach and the emerging field of the gastric microbiome. H. pylori-induced gastritis and its associated diseases including peptic ulcers and gastric cancer are addressed together with advances in diagnosis. The conclusions provide a future approach to gastric diseases underpinned by the concept that a healthy stomach is the gateway to a healthy and balanced host. This philosophy should reinforce any public health efforts designed to eradicate major gastric diseases, including stomach cancer.
We investigate magnetic data showing the presence of field‐aligned magnetosphere‐ionosphere coupling currents on 31 Cassini passes across Saturn's southern postmidnight auroral region. The currents ...are strongly modulated in magnitude, form, and position by the phase of the southern planetary period oscillations (PPOs). PPO‐independent currents are separated from PPO‐related currents using the antisymmetry of the latter with respect to PPO phase. PPO‐independent downward currents ~1.1 MA per radian of azimuth flow over the polar open field region indicative of significant plasma subcorotation are enhanced in an outer plasma sheet layer of elevated ionospheric conductivity carrying ~0.8 MA rad−1 and close principally in an upward directed current sheet at ~17°–19° ionospheric colatitude carrying ~2.3 MA rad−1 that maps to the outer hot plasma region in Saturn's magnetosphere (equatorial range ~11–16 Saturn radii (RS)) colocated with the UV oval. Subsidiary downward and upward currents ~0.5 MA rad−1 lie at ~19°–20.5° colatitude mapping to the inner hot plasma region, but no comparable currents are detected at larger colatitudes mapping to the cool plasma regime inside ~8 RS. PPO‐related currents at ~17.5°–20° colatitude overlap the main upward and subsidiary downward currents and carry comparable rotating upward and downward currents peaking at ~1.7 MA rad−1. The overall current layer colatitude is also modulated with 1° amplitude in the PPO cycle, maximum equatorward adjacent to the peak upward PPO current and maximum poleward adjacent to peak downward PPO current. This phasing requires the current system to be driven from the planetary atmosphere rather than directly from the magnetosphere.
Key Points
Planetary period oscillations (PPOs) modulate Saturn's field‐aligned currents
PPO currents are near colocated with auroral subcorotation upward currents
Current sheet latitude motions show that PPOs are driven from the atmosphere
A model is developed for the adjustment of the spatially averaged time-mean flow of a deep turbulent boundary layer over small roughness elements to a canopy of larger three-dimensional roughness ...elements. Scaling arguments identify three stages of the adjustment. First, the drag and the finite volumes of the canopy elements decelerate air parcels; the associated pressure gradient decelerates the flow within an impact region upwind of the canopy. Secondly, within an adjustment region of length of order $L_c$ downwind of the leading edge of the canopy, the flow within the canopy decelerates substantially until it comes into a local balance between downward transport of momentum by turbulent stresses and removal of momentum by the drag of the canopy elements. The adjustment length, $L_c$, is proportional to (i) the reciprocal of the roughness density (defined to be the frontal area of canopy elements per unit floor area) and (ii) the drag coefficient of individual canopy elements. Further downstream, within a roughness-change region, the canopy is shown to affect the flow above as if it were a change in roughness length, leading to the development of an internal boundary layer. A quantitative model for the adjustment of the flow is developed by calculating analytically small perturbations to a logarithmic turbulent velocity profile induced by the drag due to a sparse canopy with $L/L_c \ll 1$, where $L$ is the length of the canopy. These linearized solutions are then evaluated numerically with a nonlinear correction to account for the drag varying with the velocity. A further correction is derived to account for the finite volume of the canopy elements. The calculations are shown to agree with experimental measurements in a fine-scale vegetation canopy, when the drag is more important than the finite volume effects, and a canopy of coarse-scale cuboids, when the finite volume effects are of comparable importance to the drag in the impact region. An expression is derived showing how the effective roughness length of the canopy, $\z0eff$, is related to the drag in the canopy. The value of $\z0eff$ varies smoothly with fetch through the adjustment region from the roughness length of the upstream surface to the equilibrium roughness length of the canopy. Hence, the analysis shows how to resolve the unphysical flow singularities obtained with previous models of flow over sudden changes in surface roughness.
KEY MESSAGE : A QTL model for the genetic control of tillering in sorghum is proposed, presenting new opportunities for sorghum breeders to select germplasm with tillering characteristics appropriate ...for their target environments. Tillering in sorghum can be associated with either the carbon supply–demand (S/D) balance of the plant or an intrinsic propensity to tiller (PTT). Knowledge of the genetic control of tillering could assist breeders in selecting germplasm with tillering characteristics appropriate for their target environments. The aims of this study were to identify QTL for tillering and component traits associated with the S/D balance or PTT, to develop a framework model for the genetic control of tillering in sorghum. Four mapping populations were grown in a number of experiments in south east Queensland, Australia. The QTL analysis suggested that the contribution of traits associated with either the S/D balance or PTT to the genotypic differences in tillering differed among populations. Thirty-four tillering QTL were identified across the populations, of which 15 were novel to this study. Additionally, half of the tillering QTL co-located with QTL for component traits. A comparison of tillering QTL and candidate gene locations identified numerous coincident QTL and gene locations across populations, including the identification of common non-synonymous SNPs in the parental genotypes of two mapping populations in a sorghum homologue of MAX1, a gene involved in the control of tiller bud outgrowth through the production of strigolactones. Combined with a framework for crop physiological processes that underpin genotypic differences in tillering, the co-location of QTL for tillering and component traits and candidate genes allowed the development of a framework QTL model for the genetic control of tillering in sorghum.
Nodal root angle in sorghum influences vertical and horizontal root distribution in the soil profile and is thus relevant to drought adaptation. In this study, we report for the first time on the ...mapping of four QTL for nodal root angle (
qRA
) in sorghum, in addition to three QTL for root dry weight, two for shoot dry weight, and three for plant leaf area. Phenotyping was done at the six leaf stage for a mapping population (
n
= 141) developed by crossing two inbred sorghum lines with contrasting root angle. Nodal root angle QTL explained 58.2% of the phenotypic variance and were validated across a range of diverse inbred lines. Three of the four nodal root angle QTL showed homology to previously identified root angle QTL in rice and maize, whereas all four QTL co-located with previously identified QTL for stay-green in sorghum. A putative association between nodal root angle QTL and grain yield was identified through single marker analysis on field testing data from a subset of the mapping population grown in hybrid combination with three different tester lines. Furthermore, a putative association between nodal root angle QTL and stay-green was identified using data sets from selected sorghum nested association mapping populations segregating for root angle. The identification of nodal root angle QTL presents new opportunities for improving drought adaptation mechanisms via molecular breeding to manipulate a trait for which selection has previously been very difficult.
One of the most famous examples of adaptive radiation is that of the Galápagos finches, where skull morphology, particularly the beak, varies with feeding ecology. Yet increasingly studies are ...questioning the strength of this correlation between feeding ecology and morphology in relation to the entire neornithine radiation, suggesting that other factors also significantly affect skull evolution. Here, we broaden this debate to assess the influence of a range of ecological and life-history factors, specifically habitat density, migration, and developmental mode, in shaping avian skull evolution. Using 3D geometric morphometric data to robustly quantify skull shape for 354 extant species spanning avian diversity, we fitted flexible phylogenetic regressions and estimated evolutionary rates for each of these factors across the full data set. The results support a highly significant relationship between skull shape and both habitat density and migration, but not developmental mode. We further found heterogenous rates of evolution between different character states within habitat density, migration, and developmental mode, with rapid skull evolution in species that occupy dense habitats, are migratory, or are precocial. These patterns demonstrate that diverse factors affect the tempo and mode of avian phenotypic evolution and that skull evolution in birds is not simply a reflection of feeding ecology.
We investigate the magnetic perturbations associated with field‐aligned currents observed on 34 Cassini passes over the premidnight northern auroral region during 2008. These are found to be ...significantly modulated not only by the northern planetary‐period oscillation (PPO) system, similar to the southern currents by the southern PPO system found previously, but also by the southern PPO system as well, thus providing the first clear evidence of PPO‐related interhemispheric current flow. The principal field‐aligned currents of the two PPO systems are found to be co‐located in northern ionospheric colatitude, together with the currents of the PPO‐independent (subcorotation) system, located between the vicinity of the open‐closed field boundary and field lines mapping to ~9 Saturn radius (Rs) in the equatorial plane. All three systems are of comparable magnitude, ~3 MA in each PPO half‐cycle. Smaller PPO‐related field‐aligned currents of opposite polarity also flow in the interior region, mapping between ~6 and ~9 Rs in the equatorial plane, carrying a current of ~ ±2 MA per half‐cycle, which significantly reduce the oscillation amplitudes in the interior region. Within this interior region the amplitudes of the northern and southern oscillations are found to fall continuously with distance along the field lines from the corresponding hemisphere, thus showing the presence of cross‐field currents, with the southern oscillations being dominant in the south, and modestly lower in amplitude than the northern oscillations in the north. As in previous studies, no oscillations related to the opposite hemisphere are found on open field lines in either hemisphere.
Key Points
We study Saturn's preequinox northern auroral field‐aligned currents (FACs)
FACs modulated equally by north and south planetary period oscillations (PPOs)
Data provide first direct evidence of interhemispheric PPO‐related FAC
Oral presentations and public speaking are an important aspect of the student experience in the United Kingdom higher education. Many modules (self-contained units normally within a programme of ...study) use presentations as a form of assessment and require students to verbally engage in small and large group settings to enhance learning. Previous research evidence has indicated that many students experience fear in public speaking. The aims of this qualitative survey were two-fold. First, it sought to gather further insight into the fears experienced and strategies used by students who fear public speaking, including oral presentations. The second objective was to determine whether their fear affected their experience of higher education. A qualitative survey comprising four open-ended questions was completed by 46 undergraduate and postgraduate students with a fear of public speaking from the University of the West of England (UWE), Bristol. All participants were attending one of the Stand Up and Be Heard (SUBH) UWE library-based workshops for fear of public speaking. Thematic analysis was used to identify the following six themes, namely: fear of being judged, physical symptoms, uncertainty about the topic, negative effect on university experience, practice and preparation, and more practical support needed. The results of this survey identify the specific fears students have in public speaking and provide evidence of the overall negative effect on their higher education experience. This survey provides further evidence that higher education institutions should acknowledge public speaking fear among some students and provide more support in oral presentation assessments.
In the previously published Women's Health Initiative comparing conjugated equine estrogens with placebo in women who had undergone hysterectomy, there was a substantially lower rate of events ...related to coronary heart disease among the women receiving estrogen. The current substudy showed that coronary-artery calcium scores were lower in women receiving estrogen than in those receiving placebo. Since estrogen has complex effects, the new findings should not be construed as being clinically directive.
In a previous study in women who had undergone hysterectomy, there was a substantially lower rate of events related to coronary heart disease among the women receiving estrogen. This current substudy showed that coronary-artery calcium scores were lower in women receiving estrogen than in those receiving placebo.
Although it has been hypothesized that postmenopausal estrogen therapy delays atherosclerosis,
1
–
3
recent findings from randomized clinical trials have cast doubt on a cardioprotective role of exogenous estrogen. The Women's Health Initiative (WHI) trial of conjugated equine estrogens, administered to postmenopausal women who had undergone hysterectomy, reported a hazard ratio of 0.95 (95% confidence interval CI, 0.79 to 1.16) for nonfatal myocardial infarction plus fatal coronary heart disease (CHD) among women receiving conjugated equine estrogens as compared with those receiving placebo, but secondary analyses according to age group suggested that the results differed in younger women.
4
,
5
The corresponding hazard . . .
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