The usefulness of graphene for electronics has been limited because it does not have an energy bandgap. Although graphene nanoribbons have non-zero bandgaps, lithographic fabrication methods ...introduce defects that decouple the bandgap from electronic properties, compromising performance. Here we report direct measurements of a large intrinsic energy bandgap of approximately 50 meV in nanoribbons (width, approximately 100 nm) fabricated by high-temperature hydrogen-annealing of unzipped carbon nanotubes. The thermal energy required to promote a charge to the conduction band (the activation energy) is measured to be seven times greater than in lithographically defined nanoribbons, and is close to the width of the voltage range over which differential conductance is zero (the transport gap). This similarity suggests that the activation energy is in fact the intrinsic energy bandgap. High-resolution transmission electron and Raman microscopy, in combination with an absence of hopping conductance and stochastic charging effects, suggest a low defect density.
Abstract
Shellfish reefs across the world have been heavily degraded by mechanical harvesting, disease and declining water quality. In southern Australia, where substantial losses have occurred, ...government and non‐government efforts to restore functioning reefs are now underway with a strong focus on enhancing fish productivity. However, the capacity of these restored reefs to enhance fish production remains unknown, hampering estimates of return on investment.
We quantify the density differences of newly recruited juvenile fish and other nekton on these restored reefs, relative to those on unrestored, unstructured habitat. Fish were surveyed at three paired reef‐unstructured locations using 169 unbaited stereo video deployments during three periods over 12 months (2022–2023). We used automation software, FishID, to automatically identify, size and count fish in videos. We subsequently applied known growth and mortality parameters to model enhancement of fish productivity.
Sixteen species occurred as new recruits, with all but two found at higher densities on reefs than unstructured habitat. Enhancement of fish production from subtidal restored shellfish reefs from a single year's cohort is estimated to be, on average, 6186 kg ha
−1
year
−1
(SD 1802) after enough time has elapsed for all species to have matured. Species harvested commercially or recreationally contributed 98% of that production (6083 kg ha
−1
year
−1
, SD 1797).
Enhancement varied greatly among locations, ranging from 12,738 kg ha
−1
year
−1
(SD 2894), which is the highest yet recorded anywhere, to 1.4 kg ha
−1
year
−1
(SD 0.9).
The lack of juvenile fish at the location with the lowest estimated enhancement might be explained by the impact of overfishing on recruitment of key species or by an abundance of alternative habitat for juvenile fish.
Synthesis and applications
. The combination of underwater videos with automated data extraction provides a reliable, cost‐effective method for surveying fish on oyster reefs. By quantifying enhanced fish productivity on reefs, we provide estimates that will underpin calculations of ecological, social and financial benefits, supporting the business case for scaling‐up restoration efforts.
The fractalized Hofstadter butterfly energy spectrum predicted for magnetically confined fermions diffracted by a crystal lattice has remained beyond the reach of laboratory-accessible magnetic ...fields. We find the geometrically frustrated spin system SrCu₂(BO₃)₂ to provide a sterling demonstration of a system in which bosons confined by a magnetic and lattice potential mimic the behavior of fermions in the extreme quantum limit, giving rise to a sequence of plateaus at all magnetization $m_{z}/m_{{\rm sat}}=1/q$ ratios 9 ≥ q ≥ 2 and p/q = 2/9 ($m_{{\rm sat}}$ is the saturation magnetization) in magnetic fields up to 85 T and temperatures down to 29 mK, within the sequence of previously identified plateaus at 1/8, 1/4, and 1/3 of the saturated magnetization. We identify this hierarchy of plateaus as a consequence of confined bosons in SrCu₂(BO₃)₂ mimicking the high magnetic field fractalization predicted by the Hofstadter butterfly for fermionic systems. Such an experimental realization of the Hofstadter problem for interacting fermions has not been previously achieved in real materials, given the unachievably high magnetic flux densities or large lattice periods required. By a theoretical treatment that includes short-range repulsion in the Hofstadter treatment, stripe-like spin density-modulated phases are revealed in SrCu₂(BO₃)₂ as emergent from a fluidic fractal spectrum.
Chemoprevention for biliary tract cancers (BTC), which comprise intrahepatic cholangiocarcinoma (iCCA), extrahepatic cholangiocarcinoma (eCCA), and gallbladder cancer, is controversial. We examined ...associations between low-dose aspirin, statins, NSAIDs, and metformin with BTC risk.
We used a population-based cohort of 5.7 million persons over age 18 without personal history of cancer (except nonmelanoma skin cancer), receiving at least one commonly prescribed drug between July 1, 2005, and December 31, 2012, from the Swedish Prescribed Drug Registry. Hazard ratios (HR) were calculated using age-scaled multivariable-adjusted Cox models.
2,160 individuals developed BTC. Low-dose aspirin was not associated with BTC risk HR, 0.93; 95% confidence interval (CI), 0.81-1.07, iCCA (HR, 1.21; 95% CI, 0.93-1.57), eCCA (HR, 0.80; 95% CI, 0.60-1.07), or gallbladder cancer (HR, 0.87; 95% CI, 0.71-1.06). Statins were associated with lower risk of BTC (HR, 0.66; 95% CI, 0.56-0.78), iCCA (HR, 0.69; 95% CI, 0.50-0.95), eCCA (HR 0.54; 95% CI, 0.38-0.76), and gallbladder cancer (HR, 0.72; 95% CI, 0.57-0.91). For all BTC subtypes, combined low-dose aspirin and statins were not associated with lower risk than statins alone. NSAIDs were associated with higher risk of BTC and its subtypes. Metformin was not associated with BTC risk (HR, 0.98; 95% CI, 0.82-1.18), iCCA (HR, 1.06; 95% CI, 0.77-1.48), eCCA (HR, 1.15; 95% CI, 0.82-1.61), or gallbladder cancer (HR, 0.84; 95% CI, 0.63-1.11).
Statins were associated with a decreased risk of BTC and its subtypes. Low-dose aspirin alone was not associated with a decreased risk, and use of both was not associated with further decrease in risk beyond statins alone.
Statins were most consistently associated with a decreased risk of BTC and its subtypes.
Direct sensing of intracellular metabolite concentrations by riboswitch RNAs provides an economical and rapid means to maintain metabolic homeostasis. Since many organisms employ the same class of ...riboswitch to control different genes or transcription units, it is likely that functional variation exists in riboswitches such that activity is tuned to meet cellular needs. Using a bioinformatic approach, we have identified a region of the purine riboswitch aptamer domain that displays conservation patterns linked to riboswitch activity. Aptamer domain compositions within this region can be divided into nine classes that display a spectrum of activities. Naturally occurring compositions in this region favor rapid association rate constants and slow dissociation rate constants for ligand binding. Using X-ray crystallography and chemical probing, we demonstrate that both the free and bound states are influenced by the composition of this region and that modest sequence alterations have a dramatic impact on activity. The introduction of non-natural compositions result in the inability to regulate gene expression in vivo, suggesting that aptamer domain activity is highly plastic and thus readily tunable to meet cellular needs.
Display omitted
► Riboswitch regulatory responses are “tuned” to the needs of the transcriptional unit. ► Structure-based sequence alignment of purine riboswitches revealed new covariations. ► Nucleotides adjacent to the ligand-binding pocket “tune” ligand-binding properties. ► This work provides a conceptual framework for understanding activity tuning in RNA.
A
bstract
In the present work we study the production of vector resonances at the LHC by means of the vector boson scattering
WZ
→
WZ
and explore the sensitivities to these resonances for the ...expected future LHC luminosities. We are assuming that these vector resonances are generated dynamically from the self interactions of the longitudinal gauge bosons,
W
L
and
Z
L
, and work under the framework of the electroweak chiral Lagrangian to describe in a model independent way the supposedly strong dynamics of these modes. The properties of the vector resonances, mass, width and couplings to the
W
and
Z
gauge bosons are derived from the inverse amplitude method approach. We implement all these features into a single model, the IAM-MC, adapted for MonteCarlo, built in a Lagrangian language in terms of the electroweak chiral Lagrangian and a chiral Lagrangian for the vector resonances, which mimics the resonant behavior of the IAM and provides unitary amplitudes. The model has been implemented in MadGraph, allowing us to perform a realistic study of the signal versus background events at the LHC. In particular, we have focused our study on the
pp
→
WZjj
type of events, discussing first on the potential of the hadronic and semileptonic channels of the final
WZ
, and next exploring in more detail the most clear signals. These are provided by the leptonic decays of the gauge bosons, leading to a final state with
ℓ
1
+
ℓ
1
−
ℓ
2
+
νjj
,
ℓ
=
e
,
μ
, having a very distinctive signature, and showing clearly the emergence of the resonances with masses in the range of 1.5–2.5 TeV, which we have explored.
In low- and middle-income countries, pregnant women and newborns are more vulnerable to adverse outcomes from coronavirus disease 2019 (COVID-19). However, in Venezuela, there are no integrated data ...in a national surveillance system to identify the clinical-epidemiological characteristics and maternal-foetal outcomes of pregnant women hospitalised with COVID-19.
A retrospective study was conducted among Venezuelan pregnant women hospitalised with COVID-19 seen at the "Ruiz y Páez" University Hospital Complex and the San Cristobal Central Hospital between June 2020 and September 2021. Information was obtained from physical and digitised clinical records using a purpose-designed proforma to collect epidemiological, clinical, paraclinical, treatment, obstetric and perinatal complications, and maternal-foetal outcomes data.
A total of 80 pregnant women with confirmed severe acute respiratory syndrome coronavirus 2 infection were seen within the study period, 59 (73.8%) survived and 21 (26.2%) died. The median (interquartile range) age was 29 (23-33) years, the majority being in the third trimester of pregnancy (81.2%; n = 65). Interestingly, four (5%) pregnant women were co-infected with malaria by Plasmodium vivax and three (3.8%) with syphilis. The most frequent symptoms were fever (75%; n = 60), dry cough (68.8%; n = 55), dyspnoea (55%; n = 44), and headache (53.8%; n = 43). The most frequent maternal complications were anaemia (51.5%; n = 66) and hypertensive disorders of pregnancy (17.5%; n = 14). The most frequent perinatal complications were preterm delivery (39.2%; n = 20/51) and oligohydramnios (31.3%; n = 25). A total of 29 (36.3%) adverse foetal outcomes were documented, 21 stillbirth and eight abortions.
This is the first study to describe the clinical-epidemiological behaviour of COVID-19 in hospitalised Venezuelan pregnant women. Anaemia, hypertensive disorders of pregnancy, oligohydramnios, and low birth weight were the most frequent maternal-foetal complications in this population of pregnant women.
Understanding the heterogeneity of biomass accumulation in second‐growth tropical forests following land use abandonment is important for informing ecosystem carbon models and forest restoration ...efforts. There is an urgent need for a broad sample of second‐growth forests to enhance our knowledge of carbon accumulation in human‐dominated landscapes, especially for older forests. Puerto Rico has predominantly second‐growth forests, ranging in age from approximately 25 to more than 80 years. We used an island‐wide sample of airborne lidar from the NASA Goddard Lidar, Hyperspectral, and Thermal (G‐LiHT) Airborne Imager collected on March 2017, forest inventory data, and data on forest age, precipitation, soils, and land use to estimate aboveground biomass stocks in moist and wet, second‐growth tropical forests. Biomass accumulation rates in Puerto Rico were lower, on average, than in other Neotropical forests. Median biomass across >16,700 ha of older second‐growth forests was 105 Mg ha−1, and sampled biomass rarely surpassed 250 Mg ha−1. Differences in biomass by age were large and persistent across different substrates and land uses, with a plateau in the pattern of island‐wide biomass accumulation after about 33 years. A spatial regression model showed that multiple factors were related to biomass accumulation, including time since abandonment, geologic substrate, past land use as coffee or pasture, precipitation, topographic wetness index, and slope. Our findings have important consequences for the total carbon storage and expected climate mitigation benefits of large‐scale reforestation efforts, and highlight the value of airborne lidar for quantifying biomass variability in complex tropical landscapes.
in Spanish is available with online material.
Resumen
Entender la variabilidad de la acumulación de biomasa en los bosques tropicales secundarios originados luego del abandono del uso de la tierra es importante para informar modelos de ecosistemas, asi como esfuerzos de restauración. Existe una necesidad urgente de ampliar la muestra de bosques secundarios, especialmente de aquellos más maduros, para aumentar nuestro conocimiento de la acumulación de carbono en paisajes dominados por humanos. Puerto Rico posee una abundancia de bosques secundarios cuya edad oscila entre aproximadamente 25 y más de 80 años. Utilizamos datos de lidar aéreo colectados a través de la isla con el sensor Goddard Lidar, Hyperspectral, and Thermal (G‐LiHT) de NASA en Marzo de 2017, parcelas forestales, y datos sobre la edad del bosque, precipitación, suelos, y uso de la tierra, para estimar la biomasa aérea en los bosques tropicales secundarios húmedos y muy húmedos. La tasa de acumulación de biomasa en Puerto Rico fué más baja, en promedio, que en otros bosques neotropicales. La mediana de la biomasa en >16 700 ha de bosques secundario fue 105 Mg ha−1, y la biomasa rara vez superó los 250 Mg ha−1. Las diferencias en la biomasa por edad fueron grandes y persistentes en diferentes sustratos y usos de la tierra, con una meseta en el patrón de acumulación de biomasa a nivel isla después de 33 años. El modelo de regresión espacial mostró que múltiples factores se relacionaron con la acumulación de biomasa, incluidos el tiempo desde el abandono del suelo, el sustrato geológico, el uso anterior del suelo como café o pastura, la precipitación, índice topográfico de humedad, y pendiente. Nuestros resultados tienes consecuencias importantes para el almacenamiento total de carbono y los beneficios esperados de mitigación climática provenientes de esfuerzos de reforestación a gran escala, y resaltan el valor del lidar aéreo para cuantificar la variabilidad de la biomasa en paisajes tropicales complejos.
Understanding the heterogeneity of biomass accumulation in second‐growth tropical forests following land use abandonment is important for informing ecosystem carbon models and forest restoration efforts. Using airborne lidar data, we quantify patterns and controls on aboveground biomass accumulation in second‐growth forests of Puerto Rico.
The Josephson effect results from the coupling of two superconductors across a spacer such as an insulator, a normal metal or a ferromagnet to yield a phase coherent quantum state. However, in ...junctions with ferromagnetic spacers, very long-range Josephson effects have remained elusive. Here we demonstrate extremely long-range (micrometric) high-temperature (tens of kelvins) Josephson coupling across the half-metallic manganite La
Sr
MnO
combined with the superconducting cuprate YBa
Cu
O
. These planar junctions, in addition to large critical currents, display the hallmarks of Josephson physics, such as critical current oscillations driven by magnetic flux quantization and quantum phase locking effects under microwave excitation (Shapiro steps). The latter display an anomalous doubling of the Josephson frequency predicted by several theories. In addition to its fundamental interest, the marriage between high-temperature, dissipationless quantum coherent transport and full spin polarization brings opportunities for the practical realization of superconducting spintronics, and opens new perspectives for quantum computing.
There is evidence that chicken IL4 (chIL4) functions similarly to its mammalian analogue by enhancing type 2 T helper (Th2) humoral immunity and promoting protection against parasitic infections; ...however, no studies have been performed to assess the effect of chIL4 on the pathogenesis of Newcastle disease (ND). To assess the role of chIL4 in velogenic NDV pathogenesis we created a vNDV infectious clone expressing chIL4. We hypothesized that co-expression of chIL4 during virus replication would result in decreased inflammation caused by the Th1 response and thereby increasing survival to challenge with vNDV.
To evaluate the effect of chIL4 during early infection with velogenic Newcastle disease virus (NDV) in chickens, recombinant NDV clones expressing either chIL4 (rZJ1-IL4) or a control expressing green fluorescent protein (rZJ1-GFP) were created by inserting an expression cassette in an intergenic region of the NDV genome. The pathogenesis of rZJ1-IL4 was assessed in 4-week-old specific pathogen free chickens. The extent of virus replication was evaluated by titration in mucosal secretions and immunohistochemistry in multiple tissues. Expression of chIL4 was confirmed in tissues using immunohistochemistry.
Infection of birds with the rZJ1-IL4 resulted in successful viral replication in vivo and in vitro and generation of the chIL4 in tissues. All birds were clinically normal 2 DPI, with one bird in each group showing conjunctival swelling and enlarged spleens grossly. At 5 DPI, moderate or severe depression was observed in birds infected with rZJ1-GFP or rZJ1-IL4, respectively. Neurological signs and thymic atrophy were observed in one bird infected with rZJ1-IL4. Grossly, conjunctival swelling, mottled spleen and proventricular hemorrhages were observed at 5 DPI in one bird from each group. At 5 DPI, severe necrosis in the spleen, bursa and cecal tonsils were observed in birds infected with rZJ1-GFP, along with minimal evidence of chIL4 expression. In contrast, splenic atrophy, and moderate necrosis in the bursa and cecal tonsils were observed in birds infected with rZJ1-IL4. In addition, chIL4 signal was found in all tissues of rZJ1-IL4 birds at 5DPI.
The production of chIL4 by a recombinant NDV strain resulted in the activation of the positive feedback loop associated with IL4 production. Insertion of chIL4 into NDV may decrease necrosis to lymphoid organs while increasing the severity of lymphoid atrophy and prolonged disease. However, with a low number of birds it is difficult to determine whether these results are significant to disease outcome.
•Infection with rZJ1-IL4 resulted in successful viral replication in vivo and in vitro.•ChIL4 signal was found in the tissues of birds infected with rZJ1-IL4.•Production of chIL4 by a recombinant NDV strain decreased necrosis to lymphoid organs.
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