Small perturbations may dramatically influence the physical properties of a single non-Hermitian cavity. However, how these small perturbations interplay with bulk-edge properties is still to be demonstrated by experimentation. Here, we experimentally demonstrate edge states in coupled non-Hermitian resonators, based on a chain of all-dielectric coupled resonators where each resonator consists of two target particles. The evanescent coupling between the cavity and the target particles leads to tunable asymmetric backscattering, which plays a key role in the appearance of edge states in the bulk bandgap. We also demonstrate that these observed edge states are robust against weak disorders introduced to the system. Our study may inspire further explorations of the non-Hermitian bulk-edge properties.
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Background Despite significant global progress in reducing neonatal mortality, bacterial sepsis remains a major cause of neonatal deaths.
Klebsiella pneumoniae (K .pneumoniae ) is the leading pathogen globally underlying cases of neonatal sepsis and is frequently resistant to antibiotic treatment regimens recommended by the World Health Organization (WHO), including first-line therapy with ampicillin and gentamicin, second-line therapy with amikacin and ceftazidime, and meropenem. Maternal vaccination to prevent neonatal infection could reduce the burden ofK .pneumoniae neonatal sepsis in low- and middle-income countries (LMICs), but the potential impact of vaccination remains poorly quantified. We estimated the potential impact of such vaccination on cases and deaths ofK .pneumoniae neonatal sepsis and project the global effects of routine immunization of pregnant women with theK .pneumoniae vaccine as antimicrobial resistance (AMR) increases.Methods and findings We developed a Bayesian mixture-modeling framework to estimate the effects of a hypothetical
K .pneumoniae maternal vaccine with 70% efficacy administered with coverage equivalent to that of the maternal tetanus vaccine on neonatal sepsis infections and mortality. To parameterize our model, we used data from 3 global studies of neonatal sepsis and/or mortality—with 2,330 neonates who died with sepsis surveilled from 2016 to 2020 undertaken in 18 mainly LMICs across all WHO regions (Ethiopia, Kenya, Mali, Mozambique, Nigeria, Rwanda, Sierra Leone, South Africa, Uganda, Brazil, Italy, Greece, Pakistan, Bangladesh, India, Thailand, China, and Vietnam). Within these studies, 26.95% of fatal neonatal sepsis cases were culture-positive forK .pneumoniae . We analyzed 9,070K .pneumoniae genomes from human isolates gathered globally from 2001 to 2020 to quantify the temporal rate of acquisition of AMR genes inK .pneumoniae isolates to predict the future number of drug-resistant cases and deaths that could be averted by vaccination.Resistance rates to carbapenems are increasing most rapidly and 22.43% [95th percentile Bayesian credible interval (CrI): 5.24 to 41.42] of neonatal sepsis deaths are caused by meropenem-resistant
K .pneumoniae . Globally, we estimate that maternal vaccination could avert 80,258 [CrI: 18,084 to 189,040] neonatal deaths and 399,015 [CrI: 334,523 to 485,442] neonatal sepsis cases yearly worldwide, accounting for more than 3.40% [CrI: 0.75 to 8.01] of all neonatal deaths. The largest relative benefits are in Africa (Sierra Leone, Mali, Niger) and South-East Asia (Bangladesh) where vaccination could avert over 6% of all neonatal deaths. Nevertheless, our modeling only considers country-level trends inK .pneumoniae neonatal sepsis deaths and is unable to consider within-country variability in bacterial prevalence that may impact the projected burden of sepsis.Conclusions A
K .pneumoniae maternal vaccine could have widespread, sustained global benefits as AMR inK .pneumoniae continues to increase.Free, publicly-accessible full text available May 22, 2024 -
Key Points The 15 January 2022 Hunga Tonga‐Hunga Ha'apai eruption had four episodic seismic subevents with similar waveforms within ∼300 s An unusual upward force jump‐started each subevent A magma hammer explains the force and estimates the subsurface magma mass flux which fits the vent discharge rate based on satellite datamore » « lessFree, publicly-accessible full text available April 28, 2024
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Paysonia auriculata (Brassicaceae) produces multiple hydroxy fatty acids as major components of the seed oil. We tracked the changes in seed oil composition and gene expression during development, starting 14 days after flowers had been pollinated. Seed oil changes showed initially higher levels of saturated and unsaturated fatty acids (FAs) but little accumulation of hydroxy fatty acids (HFAs). Starting 21 days after pollination (DAP) HFA content sharply increased, and reached almost 30% at 28 DAP. Total seed oil also increased from a low of approximately 2% at 14 DAP to a high of approximately 20% by 42 DAP. We identified almost all of the fatty acid synthesis and modification genes that are known from Arabidopsis, and, in addition, a strong candidate for the hydroxylase gene that mediates the hydroxylation of fatty acids to produce valuable hydroxy fatty acids (HFAs) in this species. The gene expression network revealed is very similar to that of the emerging oil crop, Physaria fendleri , in the sister genus to Paysonia . Phylogenetic analyses indicate the hydroxylase enzyme, FAH12, evolved only once in Paysonia and Physaria , and that the enzyme is closely related to FAD2 enzymes. Phylogenetic analyses of FAD2 and FAH12 in the Brassicaceae and outgroup genera suggest that the branch leading to the hydroxylase clade of Paysonia and Physaria is under relaxed selection, compared with the strong purifying selection found across the FAD2 lineages.more » « less
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ABSTRACT The circular-crack model has been widely used in seismology to infer earthquake stress drop. A common assumption is that the background medium is isotropic, although many earthquakes occur in geologically anisotropic settings. In this article, we study the effect of anisotropy on stress drop for a circular crack model and present explicit formalism in both static and kinematic cases. In the static case, we obtain the relationship between stress drop and slip for a circular crack model in an arbitrarily anisotropic medium. Special attention is given to the transversely isotropic (TI) medium. The static formalism is useful in understanding stress drop, but not all quantities are observables. Therefore, we resort to the kinematic case, from which we can infer stress drop using recorded far-field body waves. In the kinematic case, we assume that the crack ruptures circularly and reaches the final displacement determined by the static solutions. The far-field waveforms show that the corner frequency will change with different anisotropic parameters. Finally, we calculate the stress drops for cracks in isotropic and anisotropic media using the far-field waveforms. We find that in an isotropic medium, only shear stress acting on the crack surface contributes to shear slip. However, in a TI medium, if the anisotropy symmetry axis is not perpendicular or parallel to the crack surface, a normal stress (normal to the crack surface) can produce a shear slip. In calculating stress drop for an earthquake in an anisotropic medium using far-field body waves, a large error may be introduced if we ignore the possible anisotropy in the inversion. For a TI medium with about 18% anisotropy, the misfit of inferred stress drop could be up to 41%. Considering the anisotropic information, we can further improve the accuracy of stress-drop inversion.more » « less
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Abstract Abscission, known as shattering in crop species, is a highly regulated process by which plants shed parts. Although shattering has been studied extensively in cereals and a number of regulatory genes have been identified, much diversity in the process remains to be discovered. Teff (Eragrostis tef) is a crop native to Ethiopia that is potentially highly valuable worldwide for its nutritious grain and drought tolerance. Previous work has suggested that grain shattering in Eragrostis might have little in common with other cereals. In this study, we characterize the anatomy, cellular structure, and gene regulatory control of the abscission zone (AZ) in E. tef. We show that the AZ of E. tef is a narrow stalk below the caryopsis, which is common in Eragrostis species. X-ray microscopy, scanning electron microscopy, transmission electron microscopy, and immunolocalization of cell wall components showed that the AZ cells are thin walled and break open along with programmed cell death (PCD) at seed maturity, rather than separating between cells as in other studied species. Knockout of YABBY2/SHATTERING1, documented to control abscission in several cereals, had no effect on abscission or AZ structure in E. tef. RNA sequencing analysis showed that genes related to PCD and cell wall modification are enriched in the AZ at the early seed maturity stage. These data show that E. tef drops its seeds using a unique mechanism. Our results provide the groundwork for understanding grain shattering in Eragrostis and further improvement of shattering in E. tef.more » « less
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Summary Abscission is predetermined in specialized cell layers called the abscission zone (AZ) and activated by developmental or environmental signals. In the grass family, most identified AZ genes regulate AZ anatomy, which differs among lineages. A YABBY transcription factor,
SHATTERING1 (SH1 ), is a domestication gene regulating abscission in multiple cereals, including rice andSetaria . In rice,SH1 inhibits lignification specifically in the AZ. However, the AZ ofSetaria is nonlignified throughout, raising the question of howSH1 functions in species without lignification.Crispr‐Cas9 knockout mutants of
SH1 were generated inSetaria viridis and characterized with histology, cell wall and auxin immunofluorescence, transmission electron microscopy, hormonal treatment and RNA‐Seq analysis.The
sh1 mutant lacks shattering, as expected. No differences in cell anatomy or cell wall components including lignin were observed betweensh1 and the wild‐type (WT) until abscission occurs. Chloroplasts degenerated in the AZ of WT before abscission, but degeneration was suppressed by auxin treatment. Auxin distribution and expression of auxin‐related genes differed between WT andsh1 , with the signal of an antibody to auxin detected in thesh1 chloroplast.SH1 inSetaria is required for activation of abscission through auxin signaling, which is not reported in other grass species. -
Abstract Directional transport of auxin is critical for inflorescence and floral development in flowering plants, but the role of auxin influx carriers (AUX1 proteins) has been largely overlooked. Taking advantage of available AUX1 mutants in green millet (Setaria viridis) and maize (Zea mays), we uncover previously unreported aspects of plant development that are affected by auxin influx, including higher order branches in the inflorescence, stigma branch number, glume (floral bract) development, and plant fertility. However, disruption of auxin flux does not affect all parts of the plant, with little obvious effect on inflorescence meristem size, time to flowering, and anther morphology. In double mutant studies in maize, disruptions of ZmAUX1 also affect vegetative development. A green fluorescent protein (GFP)-tagged construct of the Setaria AUX1 protein Sparse Panicle1 (SPP1) under its native promoter showed that SPP1 localizes to the plasma membrane of outer tissue layers in both roots and inflorescences, and accumulates specifically in inflorescence branch meristems, consistent with the mutant phenotype and expected auxin maxima. RNA-seq analysis indicated that most gene expression modules are conserved between mutant and wild-type plants, with only a few hundred genes differentially expressed in spp1 inflorescences. Using clustered regularly interspaced short palindromic repeats (CRISPR)–Cas9 technology, we disrupted SPP1 and the other four AUX1 homologs in S. viridis. SPP1 has a larger effect on inflorescence development than the others, although all contribute to plant height, tiller formation, and leaf and root development. The AUX1 importers are thus not fully redundant in S. viridis. Our detailed phenotypic characterization plus a stable GFP-tagged line offer tools for future dissection of the function of auxin influx proteins.more » « less
