Stocks of soil organic carbon represent a large component of the carbon cycle that may participate in climate change feedbacks, particularly on decadal and centennial timescales. For Earth system ...models (ESMs), the ability to accurately represent the global distribution of existing soil carbon stocks is a prerequisite for accurately predicting future carbon-climate feedbacks. We compared soil carbon simulations from 11 model centers to empirical data from the Harmonized World Soil Database (HWSD) and the Northern Circumpolar Soil Carbon Database (NCSCD). Model estimates of global soil carbon stocks ranged from 510 to 3040 Pg C, compared to an estimate of 1260 Pg C (with a 95% confidence interval of 890-1660 Pg C) from the HWSD. Model simulations for the high northern latitudes fell between 60 and 820 Pg C, compared to 500 Pg C (with a 95% confidence interval of 380-620 Pg C) for the NCSCD and 290 Pg C for the HWSD. Global soil carbon varied 5.9 fold across models in response to a 2.6-fold variation in global net primary productivity (NPP) and a 3.6-fold variation in global soil carbon turnover times. Model-data agreement was moderate at the biome level (R super(2) values ranged from 0.38 to 0.97 with a mean of 0.75); however, the spatial distribution of soil carbon simulated by the ESMs at the 1 degree scale was not well correlated with the HWSD (Pearson correlation coefficients less than 0.4 and root mean square errors from 9.4 to 20.8 kg C m super(-2)). In northern latitudes where the two data sets overlapped, agreement between the HWSD and the NCSCD was poor (Pearson correlation coefficient 0.33), indicating uncertainty in empirical estimates of soil carbon. We found that a reduced complexity model dependent on NPP and soil temperature explained much of the 1 degree spatial variation in soil carbon within most ESMs (R super(2) values between 0.62 and 0.93 for 9 of 11 model centers). However, the same reduced complexity model only explained 10% of the spatial variation in HWSD soil carbon when driven by observations of NPP and temperature, implying that other drivers or processes may be more important in explaining observed soil carbon distributions. The reduced complexity model also showed that differences in simulated soil carbon across ESMs were driven by differences in simulated NPP and the parameterization of soil heterotrophic respiration (inter-model R super(2) = 0.93), not by structural differences between the models. Overall, our results suggest that despite fair global-scale agreement with observational data and moderate agreement at the biome scale, most ESMs cannot reproduce grid-scale variation in soil carbon and may be missing key processes. Future work should focus on improving the simulation of driving variables for soil carbon stocks and modifying model structures to include additional processes.
In spite of the importance of phosphorus (P) as a limiting nutrient in terrestrial ecosystems, our understanding of terrestrial P dynamics and our ability to model P cycling are hampered by the lack ...of consistent measurements of soil P. The Hedley fractionation method provides a comprehensive assessment of soil P and has been widely used in recent decades. Here we expand an earlier study that summarized Hedley P data from the literature to create a larger Hedley P database and further investigate the relationships between distributions of different forms of P and the stages of soil development. Our expanded Hedley P database generally supports what the Walker and Syers (1976) conceptual model predicts: the gradual decrease and eventual depletion of primary mineral P (mainly apatite P); the continual increase and eventual dominance of occluded P; and the overall decrease of total P during soil development. However the analysis disagrees with Walker and Syers (1976) in that we found labile inorganic P(Pi) and secondary mineral Pi (non-occluded P in Walker and Syers' model) to be a significant fraction of total P throughout all soil orders with different weathering stages. By analyzing the Hedley-labile P and vegetation P demand, we found that the amount of labile P is much greater than vegetation demand, even in highly weathered soils commonly considered P limited. We conclude that labile P measured by Hedley fractionation method should not be defined as plant available P since most of this labile P likely ends up as immobilized by microbes. Our analysis of the database also shows that carbon (C) and nitrogen (N) in soil organic matter are closely linked in all soil orders, but P is decoupled from C and N in highly weathered soils with larger variations of nitrogen:organic P (N:Po) ratio and higher mean values of N:Po ratio, compared to slightly and intermediately weathered soils.
Plasmon polaritons are hybrid excitations of light and mobile electrons that can confine the energy of long-wavelength radiation at the nanoscale. Plasmon polaritons may enable many enigmatic quantum ...effects, including lasing
, topological protection
and dipole-forbidden absorption
. A necessary condition for realizing such phenomena is a long plasmonic lifetime, which is notoriously difficult to achieve for highly confined modes
. Plasmon polaritons in graphene-hybrids of Dirac quasiparticles and infrared photons-provide a platform for exploring light-matter interaction at the nanoscale
. However, plasmonic dissipation in graphene is substantial
and its fundamental limits remain undetermined. Here we use nanometre-scale infrared imaging to investigate propagating plasmon polaritons in high-mobility encapsulated graphene at cryogenic temperatures. In this regime, the propagation of plasmon polaritons is primarily restricted by the dielectric losses of the encapsulated layers, with a minor contribution from electron-phonon interactions. At liquid-nitrogen temperatures, the intrinsic plasmonic propagation length can exceed 10 micrometres, or 50 plasmonic wavelengths, thus setting a record for highly confined and tunable polariton modes. Our nanoscale imaging results reveal the physics of plasmonic dissipation and will be instrumental in mitigating such losses in heterostructure engineering applications.
We report on nano-infrared (IR) imaging studies of confined plasmon modes inside patterned graphene nanoribbons (GNRs) fabricated with high-quality chemical-vapor-deposited (CVD) graphene on Al2O3 ...substrates. The confined geometry of these ribbons leads to distinct mode patterns and strong field enhancement, both of which evolve systematically with the ribbon width. In addition, spectroscopic nanoimaging in the mid-infrared range 850–1450 cm–1 allowed us to evaluate the effect of the substrate phonons on the plasmon damping. Furthermore, we observed edge plasmons: peculiar one-dimensional modes propagating strictly along the edges of our patterned graphene nanostructures.
Tropical forests play a significant role in the global carbon cycle and global climate. However, tropical carbon cycling and the feedbacks from tropical ecosystems to the climate system remain ...critical uncertainties in the current generation of carbon–climate models. One of the major uncertainties comes from the lack of representation of phosphorus (P), currently believed to be the most limiting nutrient in tropical regions. Here we introduce P dynamics and C–N–P interactions into the CLM4-CN (Community Land Model version 4 with prognostic Carbon and Nitrogen) model and investigate the role of P cycling in controlling the productivity of tropical ecosystems. The newly developed CLM-CNP model includes all major biological and geochemical processes controlling P availability in soils and the interactions between C, N, and P cycles. Model simulations at sites along a Hawaiian soil chronosequence indicate that the introduction of P limitation greatly improved the model performance at the P-limited site. The model is also able to capture the shift in nutrient limitation along this chronosequence (from N limited to P limited), as shown in the comparison of model-simulated plant responses to fertilization with the observed data. Model simulations at Amazonian forest sites show that CLM-CNP is capable of capturing the overall trend in NPP (net primary production) along the P availability gradient. This comparison also suggests a significant interaction between nutrient limitation and land use history. Model experiments under elevated atmospheric CO2 (CO2) conditions suggest that tropical forest responses to increasing CO2 will interact strongly with changes in the P cycle. We highlight the importance of two feedback pathways (biochemical mineralization and desorption of secondary mineral P) that can significantly affect P availability and determine the extent of P limitation in tropical forests under elevated CO2. Field experiments with elevated CO2 are therefore needed to help quantify these important feedbacks. CO2 doubling model experiments show that tropical forest response to elevated CO2 can only be predicted if the interactions between C cycle and nutrient dynamics are well understood and represented in models. Predictive modeling of C–nutrient interactions will have important implications for the prediction of future carbon uptake and storage in tropical ecosystems and global climate change.
The explanation and control of phase transitions remain cornerstones of contemporary physics. Landau provided an invaluable insight into the thermodynamics of complex systems by formulating their ...phase transitions in terms of an order parameter. Within this formulation, continuous evolution of the order parameter away from zero classifies the phase transition as second-order, whereas a discontinuous change signals a first-order transition. Here we show that the temperature-tuned insulator–metal transition in the prototypical correlated electron system NdNiO3 defies this established binary classification. By harnessing a nanoscale optical probe of the local electronic conductivity, we reveal two physically distinct yet concurrent phase transitions in epitaxial NdNiO3 films. Whereas the sample bulk exhibits a first-order transition between metal and insulator phases, we resolve anomalous nanoscale domain walls in the insulating state that undergo a distinctly continuous insulator–metal transition, with hallmarks of second-order behaviour. We ascribe these domain walls to boundaries between antiferromagnetically ordered domains within the charge ordered bulk. The close correspondence of these observations to predictions from a Landau theory of coupled charge and magnetic orders highlights the importance of coupled order parameters in driving the complex phase transition in NdNiO3.
To provide a review of contemporary participation measures' conceptual foundations, psychometric properties and linkage to the International Classification of Functioning, Disability and Health ...(ICF).
Major medical databases, including PubMed, Medline, PsychInfo, and CINAHL.
Articles that described the psychometric properties of generic measures of adult participation published in English between 1998 and 2008 were included.
Two reviewers independently reviewed each measure using recognized quality criteria for health questionnaires. Individual items were linked to the ICF using established linking rules.
Eight measures met the inclusion criteria: Impact on Participation and Autonomy, ICF Measure of Participation and Activities, Keele Assessment of Participation, Assessment of Life Habits, Participation Profile, Participation Survey/Mobility, Participation Scale, and the Participation Measure for Post-Acute Care. The selected measures were based primarily on the ICF and demonstrated moderate to good validity and reliability, but psychometric information was often incomplete. The most commonly addressed ICF domains were mobility; domestic life; social interactions; major life domains; and community, social, and civic life.
This review provides tools--a detailed review of individual participation measures, a comparative table of the measures' psychometric properties, and ICF linkages-and a set of 3 guiding questions to help users select appropriate participation measures.
Purpose
The purpose was to establish the impact on survival of early detection of a local recurrence of breast cancer as compared to late detection.
Design
A meta-analysis was carried out using ...Cochrane review manager software (RevMan version 4.2). Studies were included if women were treated for primary breast cancer without evidence of distant metastasis at primary diagnosis and if these concerned routine follow-up strategies focusing on the early detection of curable recurrences. Data regarding the risk for death were derived from each study. Multi level models were used to study heterogeneity by using MLWin.
Results
Thirteen studies concerning 2,263 patients were included. Early detection of breast cancer recurrences during follow-up gave a significantly better survival as compared to late detected recurrences (HR: 1.68 (95% CI: 1.48–1.91)). Survival was better when the recurrence was found by mammography instead of physical examination or in patients without symptoms as compared to those with symptoms (HR: 2.44 (95% CI: 1.78–3.35); HR: 1.56 (95% CI: 1.36–1.79), respectively). If all breast cancer recurrences would be detected earlier, that 5–8 deaths (i.e. an absolute reduction in mortality of 17–28%) would be avoided by performing routine follow-up during a 10 year-period for 1,000 breast cancer patients.
Conclusion
These data support the hypothesis that detection of isolated loco-regional or contra-lateral breast cancer recurrences in patients without symptoms has beneficial impact on survival of breast cancer patients when compared to late symptomatic detection.
We aimed to describe labor market participation (LMP) of persons with spinal cord injury (SCI) in Switzerland, to examine potential determinants of LMP, and to compare LMP between SCI and the general ...population.
We analyzed data from 1458 participants of employable age from the cross-sectional community survey of the Swiss Spinal Cord Injury Cohort Study. Data on LMP of the Swiss general population were obtained from the Swiss Federal Statistical Office. Factors associated with employment status as well as the amount of work performed in terms of full-time equivalent (FTE) were examined with regression techniques.
53.4% of the participants were employed at the time of the study. Adjusted odds of being employed were increased for males (OR = 1.73, 95% CI 1.33-2.25) and participants with paraplegia (OR = 1.78, 95% CI 1.40-2.27). The likelihood of being employed showed a significant concave relationship with age, peaking at age 40. The relation of LMP with education was s-shaped, while LMP was linearly related to time since injury. On average, employment rates were 30% lower than in the general population. Males with tetraplegia aged between 40 and 54 showed the greatest difference. From the 771 employed persons, the majority (81.7%) worked part-time with a median of 50% FTE (IRQ: 40%-80%). Men, those with younger age, higher education, incomplete lesions, and non-traumatic etiology showed significantly increased odds of working more hours per week. Significantly more people worked part-time than in the general population with the greatest difference found for males with tetraplegia aged between 40 and 54.
LMP of persons with SCI is comparatively high in Switzerland. LMP after SCI is, however, considerably lower than in the general population. Future research needs to show whether the reduced LMP in SCI reflects individual capacity adjustment, contextual constraints on higher LMP or both.
Purpose
To determine the relationships between impact of secondary health conditions (SHCs), treatment of SHCs, and life satisfaction (LS) following spinal cord injury (SCI) across 21 countries. ...Hypotheses were as follows: (1) Persons with SCI and fewer SHCs report higher LS and (2) Persons who receive treatment for SHCs report higher LS than those who do not receive treatment.
Methods
Cross-sectional survey, including 10,499 persons with traumatic or non-traumatic SCI aged 18 years or older and living in the community. To assess SHCs, 14 items adapted from the SCI-Secondary Conditions Scale were used (range 1–5). SHCs index was calculated as the mean of all 14 items. LS was assessed using a selection of 5 items from the World Health Organization Quality of Life Assessment. LS index was calculated as the mean of these 5 items.
Results
South Korea, Germany, and Poland exhibited the highest (2.40–2.93) and Brazil, China, and Thailand the lowest (1.79–1.90) impact of SHCs. Indexes for LS and SHCs were inversely correlated (– 0.418;
p
< 0.001). Mixed Model Analysis showed that the fixed effect (key predictors of the study) of SHCs index (
p
< 0.001) and the positive interaction between SHCs index and treatment (
p
= 0.002) were significant determinants of LS.
Conclusion
Persons with SCI across the world are more likely to perceive better LS if they experience fewer SHCs and receive treatment for SHCs, in comparison to those who do not. Prevention and treatment of SHCs following SCI should be a high priority in order to improve the lived experience and enhance LS.
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