Awarding CO
offset credits may incentivize seagrass restoration projects and help reverse greenhouse gas (GHG) emissions from global seagrass loss. However, no study has quantified net GHG removal ...from the atmosphere from a seagrass restoration project, which would require coupled C
stock and GHG flux enhancement measurements, or determined whether the creditable offset benefit can finance the restoration. We measured all of the necessary GHG accounting parameters in the 7-km
Zostera marina (eelgrass) meadow in Virginia, U.S.A., part of the largest, most cost-effective meadow restoration to date, to provide the first seagrass offset finance test-of-concept. Restoring seagrass removed 9,600 tCO
from the atmosphere over 15 years but also enhanced both CH
and N
O production, releasing 950 tCO
e. Despite tripling the N
O flux to 0.06 g m
yr
and increasing CH
8-fold to 0.8 g m
yr
, the meadow now offsets 0.42 tCO
e ha
yr
, which is roughly equivalent to the seagrass sequestration rate for GHG inventory accounting but lower than the rates for temperate and tropical forests. The financial benefit for this highly successful project, $87 K at $10 MtCO
e
, defrays ~10% of the restoration cost. Managers should also consider seagrass co-benefits, which provide additional incentives for seagrass restoration.
Non-Abelian anyons promise to reveal spectacular features of quantum mechanics that could ultimately provide the foundation for a decoherence-free quantum computer. A key breakthrough in the pursuit ...of these exotic particles originated from Read and Green’s observation that the Moore-Read quantum Hall state and a (relatively simple) two-dimensional p+ip superconductor both support so-called Ising non-Abelian anyons. Here, we establish a similar correspondence between the Z3 Read-Rezayi quantum Hall state and a novel two-dimensional superconductor in which charge-2e Cooper pairs are built from fractionalized quasiparticles. In particular, both phases harbor Fibonacci anyons that—unlike Ising anyons—allow for universal topological quantum computation solely through braiding. Using a variant of Teo and Kane’s construction of non-Abelian phases from weakly coupled chains, we provide a blueprint for such a superconductor using Abelian quantum Hall states interlaced with an array of superconducting islands. Fibonacci anyons appear as neutral deconfined particles that lead to a twofold ground-state degeneracy on a torus. In contrast to a p+ip superconductor, vortices do not yield additional particle types, yet depending on nonuniversal energetics can serve as a trap for Fibonacci anyons. These results imply that one can, in principle, combine well-understood and widely available phases of matter to realize non-Abelian anyons with universal braid statistics. Numerous future directions are discussed, including speculations on alternative realizations with fewer experimental requirements.
The Atlantic salmon genome is in the process of returning to a diploid state after undergoing a whole genome duplication (WGD) event between 25 and100 million years ago. Existing data on the ...proportion of paralogous sequence variants (PSVs), multisite variants (MSVs) and other types of complex sequence variation suggest that the rediplodization phase is far from over. The aims of this study were to construct a high density linkage map for Atlantic salmon, to characterize the extent of rediploidization and to improve our understanding of genetic differences between sexes in this species.
A linkage map for Atlantic salmon comprising 29 chromosomes and 5650 single nucleotide polymorphisms (SNPs) was constructed using genotyping data from 3297 fish belonging to 143 families. Of these, 2696 SNPs were generated from ESTs or other gene associated sequences. Homeologous chromosomal regions were identified through the mapping of duplicated SNPs and through the investigation of syntenic relationships between Atlantic salmon and the reference genome sequence of the threespine stickleback (Gasterosteus aculeatus). The sex-specific linkage maps spanned a total of 2402.3 cM in females and 1746.2 cM in males, highlighting a difference in sex specific recombination rate (1.38:1) which is much lower than previously reported in Atlantic salmon. The sexes, however, displayed striking differences in the distribution of recombination sites within linkage groups, with males showing recombination strongly localized to telomeres.
The map presented here represents a valuable resource for addressing important questions of interest to evolution (the process of re-diploidization), aquaculture and salmonid life history biology and not least as a resource to aid the assembly of the forthcoming Atlantic salmon reference genome sequence.
Diffusion MRI can quantify the extent of hypoxic-ischemic brain injury after cardiac arrest. Our objective was to determine the association between the adult-derived threshold of apparent diffusion ...coefficient (ADC) <650 × 10
mm
/s in >10% of brain tissue and an unfavorable outcome after pediatric cardiac arrest. Since ADC decreases exponentially as a function of increasing age, we determined the association between (1) having >10% of brain tissue below a novel age-dependent ADC threshold, and (2) age-normalized whole-brain mean ADC and unfavorable outcome.
This was a retrospective study of patients aged ≤18 years who had cardiac arrest and a clinically obtained brain MRI within 7 days. The primary outcome was unfavorable neurologic status at hospital discharge based on the Pediatric Cerebral Performance Category score. ADC images were extracted from 3-direction diffusion imaging. We determined whether each patient had >10% of voxels with an ADC below prespecified thresholds. We computed the whole-brain mean ADC for each patient.
One hundred thirty-four patients were analyzed. Patients with ADC <650 × 10
mm
/s in >10% of voxels had 15 times higher odds (95% CI 5-65) of an unfavorable outcome compared with patients with ADC <650 × 10
mm
/s (area under the receiver operating characteristic curve AUROC 0.72 95% CI 0.63-0.80). These ADC criteria had a sensitivity and specificity of 0.49 and 0.94, respectively, and positive and negative predictive values of 0.93 and 0.52, respectively, for an unfavorable outcome. The age-dependent ADC threshold that yielded optimal sensitivity and specificity for unfavorable outcomes was <300 × 10
mm
/s below each patient's predicted whole-brain mean ADC. The sensitivity, specificity, and positive and negative predictive values for this ADC threshold were 0.53, 0.96, 0.96, and 0.54, respectively (odds ratio OR 26.4 95% CI 7.5-168.3; AUROC 0.74 95% CI 0.66-0.83). Lower age-normalized whole-brain mean ADC was also associated with an unfavorable outcome (OR 0.42 0.24-0.64, AUROC 0.76 95% CI 0.66-0.82).
Quantitative diffusion thresholds on MRI within 7 days after cardiac arrest were associated with an unfavorable outcome in children. The age-independent ADC threshold was highly specific for predicting an unfavorable outcome. However, the specificity and sensitivity increased when using age-dependent ADC thresholds. Age-dependent ADC thresholds may improve prognostic accuracy and require further investigation in larger cohorts.
This study provides Class III evidence that quantitative diffusion-weighted imaging within 7 days postarrest can predict an unfavorable clinical outcome in children.
Peripheral myelin protein 2 (P2) is a fatty acid‐binding protein expressed in vertebrate peripheral nervous system myelin, as well as in human astrocytes. Suggested functions of P2 include membrane ...stacking and lipid transport. Mutations in the PMP2 gene, encoding P2, are associated with Charcot–Marie–Tooth disease (CMT). Recent studies have revealed three novel PMP2 mutations in CMT patients. To shed light on the structure and function of these P2 variants, we used X‐ray and neutron crystallography, small‐angle X‐ray scattering, circular dichroism spectroscopy, computer simulations and lipid binding assays. The crystal and solution structures of the I50del, M114T and V115A variants of P2 showed minor differences to the wild‐type protein, whereas their thermal stability was reduced. Vesicle aggregation assays revealed no change in membrane stacking characteristics, while the variants showed altered fatty acid binding. Time‐lapse imaging of lipid bilayers indicated formation of double‐membrane structures induced by P2, which could be related to its function in stacking of two myelin membrane surfaces in vivo. In order to better understand the links between structure, dynamics and function, the crystal structure of perdeuterated P2 was refined from room temperature data using neutrons and X‐rays, and the results were compared to simulations and cryocooled crystal structures. Our data indicate similar properties for all known human P2 CMT variants; while crystal structures are nearly identical, thermal stability and function of CMT variants are impaired. Our data provide new insights into the structure–function relationships and dynamics of P2 in health and disease.
P2 is a protein of peripheral nerve myelin. We studied human P2 and three recently identified disease mutations. The data indicate effects on P2 thermal stability and dynamics by the mutations. Furthermore, room temperature crystallography using X‐rays and neutrons was used to get additional insights into P2 dynamics. Time‐lapse imaging of membrane layers showed effects of P2 on lipid membrane morphology. Overall, an improved understanding emerges about P2 structure and function.
In several species genetic differentiation across environmental gradients or between geographically separate populations has been reported to center at "genomic islands of divergence," resulting in ...heterogeneous differentiation patterns across genomes. Here, genomic regions of elevated divergence were observed on three chromosomes of the highly mobile fish Atlantic cod (Gadus morhua) within geographically fine-scaled coastal areas. The "genomic islands" extended at least 5, 9.5, and 13 megabases on linkage groups 2, 7, and 12, respectively, and coincided with large blocks of linkage disequilibrium. For each of these three chromosomes, pairs of segregating, highly divergent alleles were identified, with little or no gene exchange between them. These patterns of recombination and divergence mirror genomic signatures previously described for large polymorphic inversions, which have been shown to repress recombination across extensive chromosomal segments. The lack of genetic exchange permits divergence between noninverted and inverted chromosomes in spite of gene flow. For the rearrangements on linkage groups 2 and 12, allelic frequency shifts between coastal and oceanic environments suggest a role in ecological adaptation, in agreement with recently reported associations between molecular variation within these genomic regions and temperature, oxygen, and salinity levels. Elevated genetic differentiation in these genomic regions has previously been described on both sides of the Atlantic Ocean, and we therefore suggest that these polymorphisms are involved in adaptive divergence across the species distributional range.
IMPORTANCE: Guidelines for declaration of brain death in children were revised in 2011 by the Society of Critical Care Medicine, American Academy of Pediatrics, and Child Neurology Society. Despite ...widespread medical, legal, and ethical acceptance, ongoing controversies exist with regard to the concept of brain death and the procedures for its determination. OBJECTIVES: To determine the epidemiology and clinical characteristics of pediatric patients declared brain dead in the United States. DESIGN, SETTING, AND PARTICIPANTS: This study involved the abstraction of all patient deaths from the Virtual Pediatric Systems national multicenter database between January 1, 2012, and June 30, 2017. All patients who died in pediatric intensive care units (PICUs) were included. MAIN OUTCOMES AND MEASURES: Patient demographics, preillness developmental status, severity of illness, cause of death, PICU medical and physical length of stay, and organ donation status, as well as comparison between patients who were declared brain dead vs those who sustained cardiovascular or cardiopulmonary death. RESULTS: Of the 15 344 patients who died, 3170 (20.7%) were declared brain dead; 1861 of these patients (58.7%) were male, and 1401 (44.2%) were between 2 and 12 years of age. There was a linear association between PICU size and number of patients declared brain dead per year, with an increase of 4.27 patients (95% CI, 3.46-5.08) per 1000-patient increase in discharges (P < .001). The median (interquartile range) of patients declared brain dead per year ranged from 1 (0-3) in smaller PICUs (defined as those with <500 discharges per year) to 10 (7-15) for larger PICUs (those with 2000-4000 discharges per year). The most common causative mechanisms of brain death were hypoxic-ischemic injury owing to cardiac arrest (1672 of 3170 52.7%), shock and/or respiratory arrest without cardiac arrest (399 of 3170 12.6%), and traumatic brain injury (634 of 3170 20.0%). Most patients declared brain dead (681 of 807 84.4%) did not have preexisting neurological dysfunction. Patients who were organ donors (1568 of 3144 49.9%) remained in the PICU longer after declaration of brain death compared with those who were not donors (median interquartile range, 29 6-41 hours vs 4 1-8 hours; P < .001). CONCLUSIONS AND RELEVANCE: Brain death occurred in one-fifth of PICU deaths. Most children declared brain dead had no preexisting neurological dysfunction and had an acute hypoxic-ischemic or traumatic brain injury. Brain death determinations are infrequent, even in large PICUs, emphasizing the importance of ongoing education for medical professionals and standardization of protocols to ensure diagnostic accuracy and consistency.
OBJECTIVEDetermine the association between the extent of diffusion restriction and T2/FLAIR injury on brain MRI and outcomes after pediatric out-of-hospital cardiac arrest (OHCA).
METHODSDiffusion ...restriction and T2/FLAIR injury were described according to the pediatric MRI modification of the Alberta Stroke Program Early Computed Tomography Score for children from 2005 to 2013 who had an MRI within 14 days of OHCA. The primary outcome was unfavorable neurologic outcome defined as ≥1 change in PCPC from baseline resulting in a hospital discharge PCPC score 3, 4, 5, or 6. Patients with unfavorable outcomes were further categorized into alive with PCPC 3–5, dead due to withdrawal of life sustaining therapies for poor neurologic prognosis (WLST-neuro), or dead by neurologic criteria.
RESULTSWe evaluated MRI scans from 77 patients (median age 2.21 IQR 0.44, 13.07 years) performed 4 2, 6 days post-arrest. Patients with unfavorable outcomes had more extensive diffusion restriction (median 7 4, 10.3 vs 0 0, 0 regions, p < 0.001) and T2/FLAIR injury (5.5 2.3, 8.2 vs 0 0, 0.75 regions, p < 0.001) compared to patients with favorable outcomes. AUROC for the extent of diffusion restriction and unfavorable outcome was 0.96 (95% CI, 0.91, 0.99) and 0.92 (95% CI, 0.85, 0.97) for T2/FLAIR injury. There was no difference in extent of diffusion restriction between patients who were alive with an unfavorable outcome and patients who died from WLST-neuro (p = 0.11).
CONCLUSIONSMore extensive diffusion restriction and T2/FLAIR injury on the modsASPECTS score within the first 14 days after pediatric cardiac arrest was associated with unfavorable outcomes at hospital discharge.
To determine the variability in pediatric death by neurologic criteria (DNC) protocols between US pediatric institutions and compared to the 2011 DNC guidelines.
In this cross-sectional study of DNC ...protocols obtained from pediatric institutions in the United States via regional organ procurement organizations, protocols were evaluated across 5 domains: general DNC procedures, prerequisites, neurologic examination, apnea testing, and ancillary testing. Descriptive statistics compared protocols to each other and the 2011 guidelines.
A total of 130 protocols were analyzed with 118 dated after publication of the 2011 guidelines. Of those 118 protocols, identification of a mechanism of irreversible brain injury was required in 97%, while 67% required an observation period after acute brain injury before DNC evaluation. Most protocols required guideline-based prerequisites such as exclusion of hypotension (94%), hypothermia (97%), and metabolic derangements (92%). On neurologic examination, 91% required a lack of responsiveness, 93% no response to noxious stimuli, and 99% loss of brainstem reflexes. A total of 84% of protocols required the guideline-recommended 2 apnea tests. CO
targets were consistent with guidelines in 64%. Contrary to guidelines, 15% required ancillary testing for all patients and 15% permitted ancillary studies that are not validated in pediatrics.
Variability exists between pediatric institutional DNC protocols in all domains of DNC determination, especially with respect to apnea and ancillary testing. Better alignment of DNC protocols with national guidelines may improve the consistency and accuracy of DNC determination.
The Coronavirus disease 2019 (COVID-19) outbreak impacted health care. We investigated its impact on the time to referral and diagnosis for symptomatic cancer patients in The Netherlands. We ...performed a national retrospective cohort study utilizing primary care records linked to The Netherlands Cancer Registry. For patients with symptomatic colorectal, lung, breast, or melanoma cancer, we manually explored free and coded texts to determine the durations of the primary care (IPC) and secondary care (ISC) diagnostic intervals during the first COVID-19 wave and pre-COVID-19. We found that the median IPC duration increased for colorectal cancer from 5 days (Interquartile Range (IQR) 1-29 days) pre-COVID-19 to 44 days (IQR 6-230,
< 0.01) during the first COVID-19 wave, and for lung cancer, the duration increased from 15 days (IQR) 3-47) to 41 days (IQR 7-102,
< 0.01). For breast cancer and melanoma, the change in IPC duration was negligible. The median ISC duration only increased for breast cancer, from 3 (IQR 2-7) to 6 days (IQR 3-9,
< 0.01). For colorectal cancer, lung cancer, and melanoma, the median ISC durations were 17.5 (IQR (9-52), 18 (IQR 7-40), and 9 (IQR 3-44) days, respectively, similar to pre-COVID-19 results. In conclusion, for colorectal and lung cancer, the time to primary care referral was substantially prolonged during the first COVID-19 wave. In such crises, targeted primary care support is needed to maintain effective cancer diagnosis.
PDF
