The development of efficient solid-state sources of single photons is a major challenge in the context of quantum communication, optical quantum information processing and metrology. Such a source ...must enable the implementation of a stable, single-photon emitter, like a colour centre in diamond or a semiconductor quantum dot. Achieving a high extraction efficiency has long been recognized as a major issue, and both classical solutions and cavity quantum electrodynamics effects have been applied. We adopt a different approach, based on an InAs quantum dot embedded in a GaAs photonic nanowire with carefully tailored ends. Under optical pumping, we demonstrate a record source efficiency of 0.72, combined with pure single-photon emission. This non-resonant approach also provides broadband spontaneous emission control, thus offering appealing novel opportunities for the development of single-photon sources based on spectrally broad emitters, wavelength-tunable sources or efficient sources of entangled photon pairs.
Advancing our understanding of the connections among groundwater, food, and climate is critical to meet global food demands while optimizing water resources usage. However, our understanding of the ...linkages among groundwater, food, and climate is still limited. Here, we offer a Bayesian framework to simulate crop yield at a regional scale and quantify its relationships and associated uncertainty with climate, groundwater, agricultural, and energy-related variables. We implemented the framework in the rice-producing regions of Louisiana from 1960-2015. To build a parsimonious model, we used a probability-based variable selection approach to detect the key drivers of rice yield. Rice yield increased, groundwater declined, and area planted declined or did not change over 56yrs. The number of irrigation wells, groundwater level, air temperature, and area planted were found to be the key drivers of rice yield. The regression coefficients showed that rice yield was positively related to groundwater level, and negatively related to area planted and the number of irrigation wells. The limited influence of N fertilizer was noted on rice yield for the period when fertilizer data were available. The inverse relationship between rice yield and area planted pointed to the adaption of efficient crop management practices that maintained or increased yield, despite the decline in area planted. The farmers' ability to install irrigation wells during droughts sustained the yields over long-term but not short-term. This decline in rice yield in response to drought over the short-term might explain the negative relation between yield and irrigation wells. Overall, this work highlighted the uncertainty in relationships between rice yield and key drivers and quantified the intimate connection between food and groundwater. This work may have implications for managing two highly competing commodities (i.e., groundwater and food) in agricultural regions.
Soil moisture is a key control on runoff generation and biogeochemical processes on hillslopes. Precipitation events can evoke different soil moisture responses with depth through the soil profile, ...and responses can differ among landscape positions along a hillslope. We sought to elucidate the nature of these responses by estimating changes in water content, response time between peak precipitation and peak soil moisture, and wetting front velocities for 43 storms at 45 locations on three adjacent hillslopes within a headwater catchment of the southern Appalachian Mountains (NC, USA). We used a multivariate modeling approach to quantify the relative influences and the predictability of soil moisture responses by a combination of landscape and storm characteristics. We quantified the lag correlations between hillslope mean soil moisture and catchment runoff to demonstrate how storm properties and hillslope‐scale characteristics may influence runoff at the catchment outlet. Soil moisture responses varied widely, and no consistent patterns were observed among response metrics laterally or vertically along hillslopes. In contrast to other studies, we found that the relative influence of hillslope properties and storm characteristics varied with soil moisture responses and during storms. Antecedent conditions and storm depths influenced the strength of lag correlations between soil moisture and runoff, whereas storm mean intensity was correlated with the lag times. These results highlight the utility of intensive observations for characterizing heterogeneity in soil moisture responses, suggesting, among other things, a need for better representation of the subsurface processes in rainfall‐runoff models. Identifying the relative importance of drivers can be beneficial in building parsimonious hydrological models.
Key Points
No consistent patterns in soil moisture responses among landscape positions laterally along hillslopes
Dominant controls on soil moisture responses to storms varied with individual response metrics and during storms
Storm depth, mean intensity, and antecedent conditions mediated the soil moisture‐runoff relationships in space and time
The antimicrobial resistance (AMR) phenotypic properties, multiple drug resistance (MDR) gene profiles, and genes related to potential virulence and pathogenic properties of five Enterobacter ...bugandensis strains isolated from the International Space Station (ISS) were carried out and compared with genomes of three clinical strains. Whole genome sequences of ISS strains were characterized using the hybrid de novo assembly of Nanopore and Illumina reads. In addition to traditional microbial taxonomic approaches, multilocus sequence typing (MLST) analysis was performed to classify the phylogenetic lineage. Agar diffusion discs assay was performed to test antibiotics susceptibility. The draft genomes after assembly and scaffolding were annotated with the Rapid Annotations using Subsystems Technology and RNAmmer servers for downstream analysis.
Molecular phylogeny and whole genome analysis of the ISS strains with all publicly available Enterobacter genomes revealed that ISS strains were E. bugandensis and similar to the type strain EB-247
and two clinical isolates (153_ECLO and MBRL 1077). Comparative genomic analyses of all eight E. bungandensis strains showed, a total of 4733 genes were associated with carbohydrate metabolism (635 genes), amino acid and derivatives (496 genes), protein metabolism (291 genes), cofactors, vitamins, prosthetic groups, pigments (275 genes), membrane transport (247 genes), and RNA metabolism (239 genes). In addition, 112 genes identified in the ISS strains were involved in virulence, disease, and defense. Genes associated with resistance to antibiotics and toxic compounds, including the MDR tripartite system were also identified in the ISS strains. A multiple antibiotic resistance (MAR) locus or MAR operon encoding MarA, MarB, MarC, and MarR, which regulate more than 60 genes, including upregulation of drug efflux systems that have been reported in Escherichia coli K12, was also observed in the ISS strains.
Given the MDR results for these ISS Enterobacter genomes and increased chance of pathogenicity (PathogenFinder algorithm with > 79% probability), these species pose important health considerations for future missions. Thorough genomic characterization of the strains isolated from ISS can help to understand the pathogenic potential, and inform future missions, but analyzing them in in-vivo systems is required to discern the influence of microgravity on their pathogenicity.
Strains of
genomospecies 3 (i.e., genomovar G3 of the
species complex) have been previously isolated from diverse environments, including in association with plant roots, with algae, as part of a ...lignocellulose degrading community, from a hospital environment, as a human opportunistic pathogen, or as reported in this study, from a surface within the International Space Station. Polyphasic taxonomic methods revealed the relationship of
G3 strains to other
spp., which supports the description of a novel species. The G3 strains tested (
= 9) were phenotypically distinguishable among the strains from other genomospecies of the genus
Phylogenetic analyses of the 16S rRNA gene,
B gene, multi-locus sequence analysis, and 1,089-gene core-genome gene concatenate concur that tested G3 strains belong to the
genus and they form a clade distinct from other validly described
species. The distinctiveness of this clade was confirmed by average nucleotide identity (ANI) and
digital DNA-DNA hybridization (dDDH) comparisons between the G3 tested strains and all known
species type strains, since obtained values were considerably below the 95% (ANI) and 70% (dDDH) thresholds used for the species delineation. According to the core-genome phylogeny and ANI comparisons, the closest relatives of G3 strains were
sp. strains UGM030330-04 and K599, members of a novel genomospecies we propose to call genomovar G21. Using this polyphasic approach, we characterized the phenotypic and genotypic synapomorphies of
G3, showing it is a
bacterial species, well separated from previously named
species or other recognized genomic species. We thus propose the name
for this species previously referred to as
genomospecies 3. The type strain of
is IIF1SW-B1
(= LMG 32164 = NRRL B-65602). Comparative genomic analysis show
strains have species-specific genes associated with secretion of secondary metabolites, including an exopolysaccharide and putative adhesins and resistance to copper.
specific gene functions notably relate to surface adhesion and could be involved to colonize nutrient-poor and harsh habitats. The
strains from the ISS showed presence of a 40-kbp plasmid and several other potential mobile genetic elements detected that could also be part of conjugative elements or integrated prophages.
The photoexcitation of weakly bound complexes can lead to several decay pathways, depending on the nature of the potential energy surfaces. Upon excitation of a chromophore in a weakly bound complex, ...ionization of its neighbor upon energy transfer can occur due to a unique relaxation process known as intermolecular Coulombic decay (ICD), a phenomenon of renewed focus owing to its relevance in biological systems. Herein, we report the evidence for outer-valence ICD induced by multiphoton excitation by near-ultraviolet radiation of 4.4 eV photons, hitherto unknown in molecular systems. In the binary complexes of 2,6-difluorophenylacetylene with aliphatic amines, a resonant two-photon excitation localized on the 2,6-difluorophenylacetylene chromophore results in the formation of an amine cation following an outer-valence ICD process. The unique trends in experimentally observed translational energy distribution profiles of the amine cations following hydrogen bond dissociation, analyzed with the help of electronic structure and ab initio molecular dynamics calculations, revealed the presence of a delicate interplay of roaming dynamics, methyl-rotor dynamics, and binding energy.
This study assessed the combined effects of increased urbanization and climate change on streamflow in the Yadkin-Pee Dee watershed (North Carolina, USA) and focused on the conversion from forest to ...urban land use, the primary land use transition occurring in the watershed. We used the Soil and Water Assessment Tool to simulate future (2050–2070) streamflow and baseflow for four combined climate and land use scenarios across the Yadkin-Pee Dee River watershed and three subwatersheds. The combined scenarios pair land use change and climate change scenarios together. Compared to the baseline, projected streamflow increased in three out of four combined scenarios and decreased in one combined scenario. Baseflow decreased in all combined scenarios, but decreases were largest in subwatersheds that lost the most forest. The effects of land use change and climate change were additive, amplifying the increases in runoff and decreases in baseflow. Streamflow was influenced more strongly by climate change than land use change. However, for baseflow the reverse was true; land use change tended to drive baseflow more than climate change. Land use change was also a stronger driver than climate in the most urban subwatershed. In the most extreme land use and climate projection the volume of the 1-day, 100 year flood nearly doubled at the watershed outlet. Our results underscore the importance of forests as hydrologic regulators buffering streamflow and baseflow from hydrologic extremes. Additionally, our results suggest that land managers and policy makers need to consider the implications of forest loss on streamflow and baseflow when planning for future urbanization and climate change adaptation options.
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•Land use (LU) models for the Southeast U.S. show rapid urbanization and forest loss.•Streamflow was simulated using combinations of LU and climate models (2050–2070).•Forests can buffer streamflow during hydrologic extremes, if they are large enough.•Effects of urbanization and climate change were additive, amplifying change in flow.•Risk of increased floods and drought must be considered in watershed planning.
Four strains belonging to the family of
were isolated from different locations on the International Space Station (ISS) across two consecutive flights. Of these, three were identified as ...Gram-negative, rod-shaped, catalase-positive, oxidase-positive, motile bacteria, designated as IF7SW-B2
, IIF1SW-B5, and IIF4SW-B5, whereas the fourth was identified as
. The sequence similarity of these three ISS strains, designated as IF7SW-B2
, IIF1SW-B5, and IIF4SW-B5, was <99.4% for 16S rRNA genes and <97.3% for
gene, with the closest being
SE2.11
. Furthermore, the multi-locus sequence analysis placed these three ISS strains in the same clade of
The average nucleotide identity (ANI) values of these three ISS strains were <93% and digital DNA-DNA hybridization (dDDH) values were <46.4% with any described
species. Based on the ANI and dDDH analyses, these three ISS strains were considered as novel species belonging to the genus
The three ISS strains showed 100% ANI similarity and dDDH values with each other, indicating that these three ISS strains, isolated during various flights and from different locations, belong to the same species. These three ISS strains were found to grow optimally at temperatures from 25 to 30°C, pH 6.0 to 8.0, and NaCl 0 to 1%. Phenotypically, these three ISS strains resemble
and
since they assimilate similar sugars as sole carbon substrate when compared to other
species. Fatty acid analysis showed that the major fatty acid produced by the ISS strains are C
-ω7
and C
-ω6
. The predominant quinone was ubiquinone 10, and the major polar lipids were diphosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, and an unidentified lipid. Therefore, based on genomic, phylogenetic, biochemical, and fatty acid analyses, strains IF7SW-B2
, IIF1SW-B5, and IIF4SW-B5, are assigned to a novel species within the genus
, and the name
sp. nov. is proposed. The type strain is IF7SW-B2
(NRRL B-65601
and LMG 32165
).
•Lower-income property-owners are disproportionately exposed to flood risk.•Floodplain restoration reduces property damages from flood inundation.•Benefits of floodplain restoration outweigh the ...costs by at least 5-to-1.•Spatial optimization increases cost effectiveness of restoration efforts.•Protecting lower-income residents shifts the location of optimal interventions.
Floodplain restoration offers an opportunity to enhance communities’ resilience to flooding. However, the degree to which these interventions mitigate damages is often unknown, and identifying the best locations for implementation is a challenge. Further, the extent to which the benefits of flood mitigation are equitably distributed within communities is rarely considered in restoration projects. Here, we develop a novel framework to optimize investments in floodplain restoration that maximizes the utility of avoided damages from flood inundation for a range of budgetary constraints. We estimate the expected reduction in flood damages from restoration interventions by integrating a hydraulic flood model and an economic damage cost model. Using equity-weighted utility functions, we explicitly evaluate how the value of reduction in flood damages varies for different property owners. We demonstrate the potential of this approach in the Lewis Creek watershed, located in Vermont, USA. Under all optimal scenarios, the benefits of avoided flood damages over a 100-year time period outweigh the costs of restoration by at least 5-to-1. Floodplain restoration has the potential to reduce the present value of damages by up to $400,000, a 5% decrease from the baseline, at a cost of only $75,000. We also show that the equity-weighted utility of flood mitigation increase when restoration interventions protect the lowest-income property owners, particularly those who live in mobile homes. Together, our results illuminate the importance of evaluating the distribution of benefits and costs associated with alternative restoration strategies, as well as underscore the capacity for floodplain restoration to build resilience to flooding.
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