A growing body of research shows that democracies have more liberal trade policies than do autocracies. I argue, in contrast, that democracy has contradictory effects on different types of trade ...policies because electoral competition generates more information about some than about others. It generates considerable information about policies whose effects on consumer welfare are easy to explain to voters, but less information about policies whose effects are more complex. By increasing the transparency of some policies relative to others, democracy induces politicians to reduce transparent trade barriers but also to replace them with less transparent ones. I test this hypothesis by examining the impact of democracy on tariffs, “core” nontariff barriers (NTBs) such as quotas, and “quality” NTBs such as product standards in 75 countries in the 1990s. I find that democracy leads to lower tariffs, higher core NTBs, and even higher quality NTBs. I conclude that democracy promotes “optimal obfuscation” that allows politicians to protect their markets while maintaining a veneer of liberalization.
Since the mid-20th century, crop breeding has driven unprecedented yield gains. Breeders generally select for broadly- and reliably-performing varieties that display little genotype-by-environment ...interaction (GxE). In contrast, ecological theory predicts that across environments that vary spatially or temporally, the most productive population will be a mixture of narrowly adapted specialists. We quantified patterns of broad and narrow adaptation in modern, commercial maize (Zea mays L.) hybrids planted across 216 site-years, from 1999-2018, for the University of Illinois yield trials. We found that location was the dominant source of yield variation (44.5%), and yearly weather was the smallest (1.7%), which suggested a benefit for reliable performance in narrow biophysical environments. Varieties displayed a large "home field advantage" when growing in the location of best performance relative to other varieties. Home field advantage accounted for 19% of GxE and provided a yield increase of 1.01 ± 0.04 Mg ∙ ha-1 (7.6% relative to mean yield), yet was both smaller than predicted by a null model and unchanged across time. This counterfactual suggests that commercial breeding programs have missed an opportunity to further increase yields by leveraging local adaptation. Public breeding programs may pursue this opportunity by releasing specialist varieties that perform reliably in narrow environments. As seed sources are increasingly privatized and consolidated, this alternate strategy may compliment private breeding to support global food security.
Sequence data for >20 000 annotated genes from 56 accessions of Medicago truncatula were used to identify potential targets of positive selection, the determinants of evolutionary rate variation and ...the relative importance of positive and purifying selection in shaping nucleotide diversity. Based upon patterns of intraspecific diversity and interspecific divergence, c. 50–75% of nonsynonymous polymorphisms are subject to strong purifying selection and 1% of the sampled genes harbour a signature of positive selection. Combining polymorphism with expression data, we estimated the distribution of fitness effects and found that the proportion of deleterious mutations is significantly greater for expressed genes than for genes with undetected transcripts (nonexpressed) in a previous RNA‐seq experiment and greater for broadly expressed genes than those expressed in only a single tissue. Expression level is the strongest correlate of evolutionary rates at nonsynonymous sites, and despite multiple genomic features being significantly correlated with evolutionary rates, they explain less than 20% of the variation in nonsynonymous rates (dN) and <15% of the variation in either synonymous rates (dS) or dN:dS. Among putative targets of selection were genes involved in defence against pathogens and herbivores, genes with roles in mediating the relationship with rhizobial symbionts and one‐third of annotated histone‐lysine methyltransferases. Adaptive evolution of the methyltransferases suggests that positive selection in gene expression may have occurred through evolution of enzymes involved in epigenetic modification.
Maize stover is an important source of crop residues and a promising sustainable energy source in the United States. Stalk is the main component of stover, representing about half of stover dry ...weight. Characterization of genetic determinants of stalk traits provide a foundation to optimize maize stover as a biofuel feedstock. We investigated maize natural genetic variation in genome-wide association studies (GWAS) to detect candidate genes associated with traits related to stalk biomass (stalk diameter and plant height) and stalk anatomy (rind thickness, vascular bundle density and area).
Using a panel of 942 diverse inbred lines, 899,784 RNA-Seq derived single nucleotide polymorphism (SNP) markers were identified. Stalk traits were measured on 800 members of the panel in replicated field trials across years. GWAS revealed 16 candidate genes associated with four stalk traits. Most of the detected candidate genes were involved in fundamental cellular functions, such as regulation of gene expression and cell cycle progression. Two of the regulatory genes (Zmm22 and an ortholog of Fpa) that were associated with plant height were previously shown to be involved in regulating the vegetative to floral transition. The association of Zmm22 with plant height was confirmed using a transgenic approach. Transgenic lines with increased expression of Zmm22 showed a significant decrease in plant height as well as tassel branch number, indicating a pleiotropic effect of Zmm22.
Substantial heritable variation was observed in the association panel for stalk traits, indicating a large potential for improving useful stalk traits in breeding programs. Genome-wide association analyses detected several candidate genes associated with multiple traits, suggesting common regulatory elements underlie various stalk traits. Results of this study provide insights into the genetic control of maize stalk anatomy and biomass.
Summary
Background
Abdominal ultrasound fails to detect over one‐fourth of hepatocellular carcinoma (HCC) at an early stage in patients with cirrhosis. Identifying patients in whom ultrasound is of ...inadequate quality can inform interventions to improve surveillance effectiveness.
Aim
To evaluate and identify predictors of ultrasound quality in patients with cirrhosis.
Methods
We performed a retrospective cohort study among patients who underwent ultrasound examination for a cirrhosis‐related indication between April 2015 and October 2015. Three fellowship‐trained abdominal radiologists collectively reviewed all ultrasound exams and categorised exam quality as definitely adequate, likely adequate, likely inadequate and definitely inadequate to exclude liver lesions. We performed multivariable logistic regression to determine characteristics associated with inadequate ultrasound quality.
Results
Among 941 patients, 191 (20.3%) ultrasounds were inadequate for excluding HCC‐ 134 definitely inadequate and 57 likely inadequate. In multivariable analysis, inadequate quality was associated with male gender (OR 1.68, 95% CI 1.14–2.48), body mass index category (OR 1.67, 95% CI 1.45–1.93), Child–Pugh B or C cirrhosis (OR 1.93, 95% CI 1.32–2.81), alcohol‐related cirrhosis (OR 2.11, 95% CI 1.33–3.37), NASH cirrhosis (OR 2.87, 95% CI 1.71–4.80), and in‐patient status (OR 1.55, 95% CI 1.01–2.37). Ultrasounds were inadequate in over one‐third of patients with Child–Pugh C cirrhosis, BMI >35, or NASH cirrhosis.
Conclusions
One in five ultrasounds in patients with cirrhosis are inadequate for exclusion of HCC, which can contribute to surveillance failure. Alternative surveillance modalities are needed in subgroups prone to inadequate ultrasounds including obese patients, those with Child Pugh B or C cirrhosis, and those with alcohol‐ or NASH‐related cirrhosis.
Linked Content
This article is linked to Simmons et al and Patel papers. To view these articles visit https://doi.org/10.1111/apt.13910 and https://doi.org/10.1111/apt.13891.
Key message
Three adjacent and distinct sequence rearrangements were identified at a NAP1 locus in a soybean mutant. Genetic dissection and validation revealed the function of this gene in soybean ...trichome development.
A soybean (
Glycine max
(L.) Merr.)
gnarled
trichome mutant, exhibiting stunted trichomes compared to wild-type, was identified in a fast neutron mutant population. Genetic mapping using whole genome sequencing-based bulked segregant analysis identified a 26.6 megabase interval on chromosome 20 that co-segregated with the phenotype. Comparative genomic hybridization analysis of the mutant indicated that the chromosome 20 interval included a small structural variant within the coding region of a soybean ortholog (Glyma.20G019300) of Arabidopsis
Nck
-
Associated Protein 1
(
NAP1
), a regulator of actin nucleation during trichome morphogenesis. Sequence analysis of the candidate allele revealed multiple rearrangements within the coding region, including two deletions (approximately 1–2 kb each), a translocation, and an inversion. Further analyses revealed that the mutant allele perfectly co-segregated with the phenotype, and a wild-type soybean
NAP1
transgene functionally complemented an Arabidopsis
nap1
mutant. In addition, mapping and exon sequencing of
NAP1
in a spontaneous soybean
gnarled
trichome mutant (T31) identified a frame shift mutation resulting in a truncation of the coding region. These data indicate that the soybean
NAP1
gene is essential for proper trichome development and show the utility of the soybean fast neutron population for forward genetic approaches for identifying genes.
Oscillatory actuators are expected for various applications such as entertainment systems, consumer products, and so on. In addition, the oscillatory motion is expanded to ...multiple-degrees-of-freedom. A three-degree-of-freedom linear oscillatory actuator (3DOF-LOA) has been developed. A conventional 3DOF-LOA needs five sets of coils for a three-degree-of-freedom motion, and the forces on each axis have interfered with each other. This article proposes a novel 3DOF-LOA with three sets of coils, and its forces on each axis do not interfere with each other. The magnetic structure and the operating principle of the proposed 3DOF-LOA are described. The force characteristics are calculated using a 3-D finite-element method. It is investigated that the proposed actuator can be driven three-axis by only three-coils, and has no interference of forces between each axis.
While it is accepted that silica‐rich melts behave anomalously with a decrease of their viscosity at increased pressures (P), the viscosity of silica‐poor melts is much less constrained. However, ...modeling of mantle melts dynamics throughout Earth's history, including the magma ocean era, requires precise knowledge of the viscous properties of silica‐poor magmas. We extend here our previous measurements on fayalite melt to natural end‐members pyroxenite melts (MgSiO3 and CaSiO3) using in situ X‐ray radiography up to 8 GPa. For all compositions, viscosity decreases with P, rapidly below 5 GPa and slowly above. The magnitude of the viscosity decrease is larger for pyroxene melts than for fayalite melt and larger for the Ca end‐member within pyroxene melts. The anomalous viscosity decrease appears to be a universal behavior for magmas up to 13 GPa, while the P dependence of viscosity beyond this remains to be measured. These results imply that mantle melts are very pervasive at depth.
Key Points
Viscosity of pyroxene and olivine melts decreases with increased pressure up to 8 GPa
Lower values of melt viscosity at higher pressures suggests tetrahedral ring units control viscosity
A compilation of data obtained on melts shows that their viscosity converge toward a value of 20–30 mPa s at the highest P investigated
Glycinergic neurons provide an important mechanism to control excitation of motoneurons in the brainstem and a reduction or loss of glycinergic inhibition can be deleterious by leading to ...hyperexcitation such as in hyperekplexia or neurodegeneration and neuronal death as in amyotrophic lateral sclerosis (ALS). Second messenger systems that change cyclic AMP and lead to phosphorylation of the alpha 3 subunit of the glycine receptor (GlyR alpha 3) have been shown to be potent modulators of synaptic inhibition in the spinal cord and brain stem. In this study we analyzed the role of GlyR alpha 3 in synaptic inhibition to the hypoglossal nucleus using Glra3 (the gene encoding the glycine receptor alpha 3 subunit) knockout mice. We observed that baseline glycinergic synaptic transmission to nucleus of hypoglossal motoneurons is rather normal in Glra3 knockout mice. Interestingly, we found that the modulation of synaptic transmission by cAMP-mediated pathways appeared to be reduced in Glra3 knockout mice. In the second postnatal week the forskolin-induced increase of miniature inhibitory postsynaptic potential (mIPSC) frequency was significantly larger in control as compared to Glra3 knockout mice suggesting that presynaptic glycine release in the hypoglossal nucleus is partially depending on GlyR alpha 3.
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