Ecology Letters (2011) 14: 349–357
The earth’s future climate state is highly dependent upon changes in terrestrial C storage in response to rising concentrations of atmospheric CO2. Here we show ...that consistently enhanced rates of net primary production (NPP) are sustained by a C‐cascade through the root‐microbe‐soil system; increases in the flux of C belowground under elevated CO2 stimulated microbial activity, accelerated the rate of soil organic matter decomposition and stimulated tree uptake of N bound to this SOM. This process set into motion a positive feedback maintaining greater C gain under elevated CO2 as a result of increases in canopy N content and higher photosynthetic N‐use efficiency. The ecosystem‐level consequence of the enhanced requirement for N and the exchange of plant C for N belowground is the dominance of C storage in tree biomass but the preclusion of a large C sink in the soil.
The descent of the westerly phase of the quasi‐biennial oscillation (QBO) in equatorial stratospheric zonal wind was interrupted by the development of easterlies near 40 hPa (~23 km altitude) in ...early 2016. We use tropical meteorological analyses of wind and temperature to describe in detail the special circumstances by which equatorward‐propagating planetary waves produced this unprecedented disruption in the QBO. Our findings show that the subtropical easterly jet in the winter lower stratosphere during the 2015–2016 winter was anomalously weak owing to (1) the timing of the QBO relative to the annual cycle and (2) an extreme El Niño event. The weak jet allowed an unusually large flux of westward momentum to propagate from the extratropical Northern Hemisphere to the equator near the 40 hPa level. Consequently, the QBO westerlies at that level experienced sustained easterly acceleration from extratropical wave breaking, leading to the observed wind reversal.
Key Points
The disruption of the quasi‐biennial oscillation in early 2016 was caused by extratropical Rossby wave breaking
Stratospheric subtropical easterlies were anomalously weak due to combined effects from an extreme El Niño and annual variability
Westerlies in the Northern Hemisphere subtropics allowed Rossby waves to propagate from the midlatitudes to the equator and break there
This paper characterizes the impacts of sudden stratospheric warmings (SSWs) and mesospheric coolings (MCs) on the light species distribution (i.e., helium He, and atomic hydrogen H) of the ...thermosphere using a combined data‐modeling approach. Performing a set of numerical experiments with a general circulation model whose middle atmospheric dynamical and thermodynamical fields were constrained using a numerical weather prediction system, we simulate the effects of SSWs and MCs on light chemical species, and via comparisons with two data sets taken from the mesosphere and thermosphere, we quantify the associated variability in light species abundances and mass density. Large depletions in the observed and modeled polar H abundance in the mesosphere and lower thermosphere (MLT) occur with MC onset, as opposed to SSW onset. Depletions in all light thermospheric species at high northern latitudes extend up to the exobase in our model simulations during the January 2013 SSW/MC period, with the largest depletions simulated for the lightest species. Further, our modeling work substantiates the paradigm of increased mixing in the MLT driven by a meridional residual circulation during SSWs resulting from enhanced small‐scale gravity wave and migrating semidiurnal tidal forcing; the former being the primary driver and the latter of secondary but notable importance in our model simulations. SSW/MC induced light species variability then gets projected upward into the thermosphere through molecular diffusion. Modeled light species variability during the January 2013 SSW/MC event suggests SSW/MC signatures could be present in the topside ionosphere and plasmasphere.
Plain Language Summary
Sudden stratospheric warmings (SSWs) and mesospheric coolings (MCs) are episodic polar middle atmospheric (∼12–80 km or ∼7–50 miles altitude) dynamical weather events driven by increased wave forcing from the troposphere. These events are known to have global effects on the meteorology of the upper atmosphere (i.e., the thermosphere and ionosphere). Observational and modeling evidence presented in this study demonstrate that SSWs and MCs in the middle atmosphere act to drive changes in the chemical composition of the upper atmosphere through an intricate series of processes, set in motion by SSW/MC enhancements in lower and middle atmospheric wave forcing. Our results show that SSW/MC driven changes in particularly light species like hydrogen extend well into the transition region between Earth's atmosphere and outer space. This implies that middle atmospheric weather may have an impact on the plasma populations several Earth radii above Earth's surface (∼10,000 miles or more away).
Key Points
Decreases in helium and atomic hydrogen concentration at high northern latitudes occur at the onset of mesospheric cooling events
Small‐scale GW and tidal activity drives enhanced meridional transport which extends light species decreases up to the exobase in TIME‐GCM
Accompanying decreases in O+ and H+ during middle atmospheric dynamical events have implications for the inner magnetosphere
We previously reported a genome-wide association study (GWAS) identifying 14 susceptibility loci for generalized vitiligo. We report here a second GWAS (450 individuals with vitiligo (cases) and ...3,182 controls), an independent replication study (1,440 cases and 1,316 controls) and a meta-analysis (3,187 cases and 6,723 controls) identifying 13 additional vitiligo-associated loci. These include OCA2-HERC2 (combined P = 3.80 × 10(-8)), MC1R (P = 1.82 × 10(-13)), a region near TYR (P = 1.57 × 10(-13)), IFIH1 (P = 4.91 × 10(-15)), CD80 (P = 3.78 × 10(-10)), CLNK (P = 1.56 × 10(-8)), BACH2 (P = 2.53 × 10(-8)), SLA (P = 1.58 × 10(-8)), CASP7 (P = 3.56 × 10(-8)), CD44 (P = 1.78 × 10(-9)), IKZF4 (P = 2.75 × 10(-14)), SH2B3 (P = 3.54 × 10(-18)) and TOB2 (P = 6.81 × 10(-10)). Most vitiligo susceptibility loci encode immunoregulatory proteins or melanocyte components that likely mediate immune targeting and the relationships among vitiligo, melanoma, and eye, skin and hair coloration.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Vitiligo is an autoimmune disease in which depigmented skin results from the destruction of melanocytes, with epidemiological association with other autoimmune diseases. In previous linkage and ...genome-wide association studies (GWAS1 and GWAS2), we identified 27 vitiligo susceptibility loci in patients of European ancestry. We carried out a third GWAS (GWAS3) in European-ancestry subjects, with augmented GWAS1 and GWAS2 controls, genome-wide imputation, and meta-analysis of all three GWAS, followed by an independent replication. The combined analyses, with 4,680 cases and 39,586 controls, identified 23 new significantly associated loci and 7 suggestive loci. Most encode immune and apoptotic regulators, with some also associated with other autoimmune diseases, as well as several melanocyte regulators. Bioinformatic analyses indicate a predominance of causal regulatory variation, some of which corresponds to expression quantitative trait loci (eQTLs) at these loci. Together, the identified genes provide a framework for the genetic architecture and pathobiology of vitiligo, highlight relationships with other autoimmune diseases and melanoma, and offer potential targets for treatment.
We examine the evolution of the quasi 2‐day wave in the middle atmosphere during the period from 5 January to 5 February 2006 using global synoptic meteorological fields from the high‐altitude Navy ...Operational Global Atmospheric Prediction System Advanced Level Physics, High Altitude (NOGAPS‐ALPHA) forecast‐assimilation system. This period is characterized by a high level of planetary wave activity in the Northern Hemisphere (winter) extratropical stratosphere prior to a sudden stratospheric warming (SSW) on 20 January 2006. Space‐time spectral analysis of 6‐hourly NOGAPS‐ALPHA fields finds the largest quasi 2‐day wave amplitudes in the Southern Hemisphere (summer) extratropical upper mesosphere. Eliassen‐Palm flux diagnostics indicate that this extratropical quasi 2‐day wave is related to baroclinic instability along the equatorward flank of the summer easterly jet. The quasi 2‐day wave is also evident in NOGAPS‐ALPHA water vapor fields near the tropical stratopause and is related to barotropic instability. We find that the strong planetary wave activity leading up to the SSW produced an enhanced northward component of the residual meridional circulation that influenced the background zonal winds and, by extension, the quasi 2‐day wave forcing in both the tropical and extratropical regions. In the tropical region, the combination of enhanced horizontal momentum advection by the residual meridional circulation and inertially unstable circulations related to planetary wave breaking in the subtropics produced conditions favoring barotropic instability. In the extratropical region, the enhanced residual meridional circulation altered the zonal wind tendency through increased Coriolis torque.
Recent advances in developing accurate, physics‐based models of the coupled ionosphere‐thermosphere (CIT) system have now made these models an integral part of next‐generation space weather ...prediction capabilities. These advances have produced a better understanding of how the CIT is affected by variability in the neutral lower atmosphere. However, the impacts on the CIT of lower atmospheric variability over time scales with characteristic periods longer than ~10 days have received little attention, despite clear evidence of this variability in atmospheric circulation patterns throughout the stratosphere, mesosphere, and lower thermosphere. This review synthesizes the state of knowledge on long‐term variability (>10 days) originating in the lower atmosphere and its impacts on the CIT, highlighting the following critical points and challenges: (a) planetary wave oscillations are likely to couple the lower and upper atmospheres, especially those corresponding to normal modes of the atmosphere, but it remains unclear whether they impact the ionosphere directly via wind‐dynamo coupling, or indirectly via modulation of solar and lunar tides; (b) while fast moving planetary wave oscillations are ubiquitous in the CIT especially during solstices, there is only sporadic evidence that the slowest moving modes are also present in the upper atmosphere; (c) there is abundant evidence of long‐term variations of tidal amplitudes in the CIT, but how and why such variations occur still remain; (d) interseasonal variations associated with major tropospheric and stratospheric variability have been observed, but the physical pathways are still poorly understood.
Key Points
Large‐scale oscillations with periods longer than 10 days are a potential source of space weather predictability
Ionospheric signatures of intraseasonal behavior are ubiquitous, but their origins are poorly understood
Observational and modeling studies of pathways linking oscillations from the lower atmosphere to the ionosphere are needed
In the North Dublin Population Stroke Study, we investigated the risk of recurrent stroke within the 14-day time window recommended for endarterectomy.
In a population-based prospective cohort study, ...all ischemic stroke patients were identified over 1 year and categorized into those with (CS-positive) and without (CS-negative) ipsilateral carotid stenosis (CS) (≥50% lumen narrowing). Nonprocedural stroke recurrence was determined at 72 hours and 7 and 14 days.
Of 365 ischemic stroke patients with carotid imaging, 51 were excluded due to posterior circulation or nonlateralizing stroke, ipsilateral carotid occlusion, or intracranial stenosis, leaving 314 included for analysis (36 CS-positive and 278 CS-negative). Recurrent stroke occurred in 5.6% (2/36) CS-positive and 0.4% (1/278) CS-negative patients by 72 hours of symptom onset (p =0.003), 5.6% (2/36) CS-positive and 0.7% (2/278) CS-negative patients (p =0.01) by 7 days, and in 8.3% (3/36) CS-positive and 1.8% (5/278) CS-negative patients by 14 days (p =0.02). On multivariable Cox regression analysis, CS was the only independent predictor of recurrence at 72 hours (adjusted hazard ratio HR 36.1, 95% confidence interval CI 1.6-837.5, p =0.03), and 7 days (HR 9.1, 1.1-79.2, p =0.05), with a trend at 14 days (HR 4.6, 0.9-22.8, p =0.06).
Although only a minority of patients with symptomatic CS had a recurrent stroke within 14 days, early recurrent stroke risk was high, particularly within the first 72 hours. Earlier carotid revascularization or improved acute medical treatment may reduce recurrence in this high-risk group.
•The impact of environment and community on school performance was assessed.•Exposure to industrial hazards increases absenteeism among school-aged children.•Building facilities and perceptions of ...safety impact performance and absenteeism.•Consideration of school and community factors is important for adolescent success.
School facility conditions, environment, and perceptions of safety and learning have been investigated for their impact on child development. However, it is important to consider how the environment separately influences academic performance and attendance after controlling for school and community factors. Using results from the Maryland School Assessment, we considered outcomes of school-level proficiency in reading and math plus attendance and chronic absences, defined as missing 20 or more days, for grades 3–5 and 6–8 at 158 urban schools. Characteristics of the environment included school facility conditions, density of nearby roads, and an index industrial air pollution. Perceptions of school safety, learning, and institutional environment were acquired from a School Climate Survey. Also considered were neighborhood factors at the community statistical area, including demographics, crime, and poverty based on school location. Poisson regression adjusted for over-dispersion was used to model academic achievement and multiple linear models were used for attendance. Each 10-unit change in facility condition index, denoting worse quality buildings, was associated with a decrease in reading (1.0% (95% CI: 0.1–1.9%) and math scores (0.21% (95% CI: 0.20-0.40), while chronic absences increased by 0.75% (95% CI: 0.30–1.39). Each log increase the EPA’s Risk Screening Environmental Indicator (RSEI) value for industrial hazards, resulted in a marginally significant trend of increasing absenteeism (p < 0.06), but no association was observed with academic achievement. All results were robust to school-level measures of racial composition, free and reduced meals eligibility, and community poverty and crime. These findings provide empirical evidence for the importance of the community and school environment, including building conditions and neighborhood toxic substance risk, on academic achievement and attendance.
This study uses hourly meteor wind measurements from a longitudinal array of 10 high-latitude SuperDARN high-frequency (HF) radars to isolate the migrating diurnal, semidiurnal, and terdiurnal tides ...at mesosphere–lower-thermosphere (MLT) altitudes. The planetary-scale array of radars covers 180∘ of longitude, with 8 out of 10 radars being in near-continuous operation since the year 2000. Time series spanning 16 years of tidal amplitudes and phases in both zonal and meridional wind are presented, along with their respective annual climatologies. The method to isolate the migrating tides from SuperDARN meteor winds is validated using 2 years of winds from a high-altitude meteorological analysis system. The validation steps demonstrate that, given the geographical spread of the radar stations, the derived tidal modes are most closely representative of the migrating tides at 60∘ N. Some of the main characteristics of the observed migrating tides are that the semidiurnal tide shows sharp phase jumps around the equinoxes and peak amplitudes during early fall and that the terdiurnal tide shows a pronounced secondary amplitude peak around day of year (DOY) 265. In addition, the diurnal tide is found to show a bi-modal circular polarization phase relation between summer and winter.
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