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We build a model of bond yields in an economy with secular changes to inflation, real rate, and output growth. Long-run restrictions identify nominal shocks that do not influence the long-run real rate and output growth. Before the anchoring of inflation around the mid-1990s, nominal shocks lifted the output gap and inflation. This led to a higher and steeper yield curve because the short rate was expected to peak after several quarters, following declines in the responses of growth and inflation. With inflation anchored, nominal shocks have small impacts on inflation, output, and bond yields, mostly via the term premium.

Soil carbon dynamics is strongly controlled by depth globally, with increasingly slow dynamics found at depth. The mechanistic basis remains however controversial, limiting our ability to predict carbon cycle-climate feedbacks. Combining radiocarbon and thermal analyses with long-term incubations in absence/presence of continuously 13C/14C-labelled plants, we show here that bioenergetic constraints of decomposers consistently drive the depth-dependency of soil carbon dynamics over a range of mineral reactivity contexts. The slow dynamics of subsoil carbon was tightly related to both its low energy density and high activation energy of decomposition, leading to an unfavorable ‘return-on-energy-investment’ for decomposers. We also observed strong acceleration of millennia-old subsoil carbon decomposition induced by roots (‘rhizosphere priming’), showing that sufficient supply of energy by roots is able to alleviate the strong energy limitation of decomposition. These findings demonstrate that subsoil carbon persistence results from its poor energy quality together with the lack of energy supply by roots due to their low density at depth. These findings provide insights into the bioenergetic control of SOC persistence and indicate that an increase in plant rooting depth induced by global change could threaten the storage of millennia-old SOC in deep layers.

Purpose: Germline mutations in genes encoding mitochondrial succinate dehydrogenase (SDH) are found in patients with paragangliomas, pheochromocytomas, gastrointestinal stromal tumors, and renal cancers. SDH inactivation leads to a massive accumulation of succinate, acting as an oncometabolite and which levels, assessed on surgically resected tissue are a highly specific biomarker of SDHx-mutated tumors. The aim of this study was to address the feasibility of detecting succinate in vivo by magnetic resonance spectroscopy.Experimental Design: A pulsed proton magnetic resonance spectroscopy (1H-MRS) sequence was developed, optimized, and applied to image nude mice grafted with Sdhb−/− or wild-type chromaffin cells. The method was then applied to patients with paraganglioma carrying (n = 5) or not (n = 4) an SDHx gene mutation. Following surgery, succinate was measured using gas chromatography/mass spectrometry, and SDH protein expression was assessed by immunohistochemistry in resected tumors.Results: A succinate peak was observed at 2.44 ppm by 1H-MRS in all Sdhb−/−-derived tumors in mice and in all paragangliomas of patients carrying an SDHx gene mutation, but neither in wild-type mouse tumors nor in patients exempt of SDHx mutation. In one patient, 1H-MRS results led to the identification of an unsuspected SDHA gene mutation. In another case, it helped define the pathogenicity of a variant of unknown significance in the SDHB gene.Conclusions: Detection of succinate by 1H-MRS is a highly specific and sensitive hallmark of SDHx mutations. This noninvasive approach is a simple and robust method allowing in vivo detection of the major biomarker of SDHx-mutated tumors. Clin Cancer Res; 22(5); 1120–9. ©2015 AACR.

Figure S1- Phantom spectra of succinate at 4.7T and 3 T. Figure S2- SUCCES in Sdhb-/- allografted tumors in mice. Figure S3 - SUCCES in SDHx-mutated PPGL. Figure S4 - SUCCES in non SDHx-mutated PPGL.

There is currently an intense debate about the potential for additional organic carbon storage in soil, the strategies by which it may be accomplished and what the actual benefits might be for agriculture and the climate. Controversy forms an essential part of the scientific process, but on the topic of soil carbon storage, it may confuse the agricultural community and the general public and may delay actions to fight climate change. In an attempt to shed light on this topic, the originality of this article lies in its intention to provide a balanced description of contradictory scientific opinions on soil carbon storage and to examine how the scientific community can support decision-making despite the controversy. In the first part, we review and attempt to reconcile conflicting views on the mechanisms controlling organic carbon dynamics in soil. We discuss the divergent opinions about chemical recalcitrance, the microbial or plant origin of persistent soil organic matter, the contribution of particulate organic matter to additional organic carbon storage in soil, and the spatial and energetic inaccessibility of soil organic matter to decomposers. In the second part, we examine the advantages and limitations of big data management and modeling, which are essential tools to link the latest scientific theories with the actions taken by stakeholders. Finally, we show how the analysis and discussion of controversies can guide scientists in supporting stakeholders for the design of (i) appropriate trade-offs for biomass use in agriculture and forestry and (ii) climate-smart management practices, keeping in mind their still unresolved effects on soil carbon storage.

In mid-2020, the University of Liège (ULiège, Belgium) commissioned the ULiège Video Game Research Laboratory (Liège Game Lab) and the AR/VR Lab of the HEC-Management School of ULiège to create a serious game to raise awareness of preventive measures for its university community. This project has its origins in two objectives of the institutional policy of ULiège in response to the crisis caused by SARS-CoV-2 to raise awareness among community members of various preventive actions that can reduce the spread of the virus and to inform about the emergence and progression of a pandemic. After almost two years of design, the project resulted in the creation of SARS Wars, a decision-making management game for browsers and smartphones. This article presents the creative process of the game, specifically the integration of an adapted SEIR (susceptible-exposed-infectious-recovered) model, as well as the modeling of intercompartmental circulation dynamics in the game’s algorithm, and the various limitations observed regarding the game’s original missions and possibilities for future work. The SARS-CoV-2 video game project may be considered an innovative way to translate epidemiology into a language that can be used in the scope of citizen sciences. On the one hand, it provides an engaging tool and encourages active participation of the audience. On the other hand, it allows us to have a better understanding of the dynamic changes of a pandemic or an epidemic (crisis preparedness, monitoring, and control) and to anticipate potential consequences in the given parameters at set time (emerging risk identification), while offering insights for impact on some parameters on motivation (social science aspect).

During the COVID-19 pandemic, barrier gestures such as mask wearing, physical distancing, greetings without contact, one-way circulation flow, and hand sanitization were major strategies to prevent the spread of SARS-CoV-2, but they were only useful if consistently applied. This survey was a follow-up of the first survey performed in 2020 at the University of Liège. We aim to evaluate the compliance with these gestures on campuses and examine differences in the extent of the compliance observed in different educational activities and contexts. During 3.5 months, the counting of compliant and non-compliant behaviors was performed each week in randomly selected rooms. Using data collected during both surveys (2020 and 2021), binomial negative regression models of compliance depending on periods (teaching periods and exam sessions), type of rooms, and campuses were conducted to evaluate prevalence ratios of compliance. The percentage of compliance in this second survey was the highest for mask wearing and physical distancing during educational activities (90% and 88%, respectively) and lowest for physical distancing outside educational activities and hand sanitization (45% and 52%, respectively). Multivariate analyses revealed that the compliance with most gestures was significantly higher in teaching rooms than in hallways and restaurants and during exam sessions. The compliance with physical distancing was significantly higher (from 66%) in auditoriums, where students had to remain seated, than during practical works that allowed or required free movement. Therefore, the compliance with barrier gestures was associated with contextual settings, which should be considered when communicating and managing barrier gestures. Further studies should specify and confirm the determining contextual characteristics regarding the compliance with barrier gestures in times of pandemic.

Warming-induced microbial decomposition of organic matter in permafrost soils constitutes a climate-change feedback of uncertain magnitude. While physicochemical constraints on soil functioning are relatively well understood, the constraints attributable to microbial community composition remain unclear. Here we show that biogeochemical processes in permafrost can be impaired by missing functions in the microbial community-functional limitations-probably due to environmental filtering of the microbial community over millennia-long freezing. We inoculated Yedoma permafrost with a functionally diverse exogenous microbial community to test this mechanism by introducing potentially missing microbial functions. This initiated nitrification activity and increased CO2 production by 38% over 161 days. The changes in soil functioning were strongly associated with an altered microbial community composition, rather than with changes in soil chemistry or microbial biomass. The present permafrost microbial community composition thus constrains carbon and nitrogen biogeochemical processes, but microbial colonization, likely to occur upon permafrost thaw in situ, can alleviate such functional limitations. Accounting for functional limitations and their alleviation could strongly increase our estimate of the vulnerability of permafrost soil organic matter to decomposition and the resulting global climate feedback. Carbon dioxide emissions from permafrost thaw are substantially enhanced by relieving microbial functional limitations, according to incubation experiments on Yedoma permafrost.

International audience; The priming effect (PE) is a key mechanism contributing to the carbon balance of the soil ecosystem. Almost 100 years of research since its discovery in 1926 have led to a rich body of scientific publications to identify the drivers and mechanisms involved. A few review articles have summarised the acquired knowledge; the last major one was published in 2010. Since then, knowledge on the soil microbial communities involved in PE and in PE + C sequestration mechanisms has been considerably renewed. This article reviews current knowledge on soil PE to state to what extent new insights may improve our ability to understand and predict the evolution of soil C stocks. We propose a framework to unify the different concepts and terms that have emerged from the international scientific community on this topic, report recent discoveries and identify key research needs. Seventy per cent of the studies on the soil PE were published in the last 10 years, illustrating a renewed interest for PE, probably linked to the increased concern about the importance of soil carbon for climate change and food security issues. Among all the drivers and mechanisms proposed along with the different studies to explain PE, some are named differently but actually refer to the same object. This overall introduces 'artificial' complexity for the mechanistic understanding of PE, and we propose a common, shared terminology. Despite the remaining knowledge gaps, consistent progress has been achieved to decipher the abiotic mechanisms underlying PE, together with the role of enzymes and the identity of the microbial actors involved. However, including PE into mechanistic models of SOM dynamics remains challenging as long as the mechanisms are not fully understood. In the meantime, empirical alternatives are available that reproduce observations accurately when calibration is robust. Based on the current state of knowledge, we propose different scenarios depicting to what extent PE may impact ecosystem services under climate change conditions.

Soil enzymes are central to ecosystem processes because they mediate numerous reactions that are essential in biogeochemical cycles. However, how soil enzyme activities will respond to global warming is uncertain. We reviewed the literature on mechanisms linking temperature effects on soil enzymes and microbial communities, and outlined a conceptual overview on how these changes may influence soil carbon fluxes in terrestrial ecosystems. At the enzyme scale, although temperature can have a positive effect on enzymatic catalytic power in the short term (i.e. via the instantaneous response of activity), this effect can be countered over time by enzyme inactivation and reduced substrate affinity. At the microbial scale, short-term warming can increase enzymatic catalytic power via accelerated synthesis and microbial turnover, but shifts in microbial community composition and growth efficiency may mediate the effect of warming in the long term. Although increasing enzyme activities may accelerate labile carbon decomposition over months to years, our literature review highlights that this initial stage can be followed by the following phases: (a) a reduction in soil carbon loss, due to changing carbon use efficiency among communities or substrate depletion, which together can decrease microbial biomass and enzyme activity and (b) an acceleration of soil carbon loss, due to shifts in microbial community structure and greater allocation to oxidative enzymes for recalcitrant carbon degradation. Studies that bridge scales in time and space are required to assess whether there will be an attenuation or acceleration of soil carbon loss through changes in enzyme activities in the very long term. We conclude that soil enzymes determine the sensitivity of soil carbon to warming, but that the microbial community and enzymatic traits that mediate this effect change over time. Improving representation of enzymes in soil carbon models requires long-term studies that characterize the response of wide-ranging hydrolytic and oxidative enzymatic traits—catalytic power, kinetics, inactivation—and the microbial community responses that govern enzyme synthesis.

In the context of COVID-19 in Belgium, face-to-face teaching activities were allowed in Belgian universities at the beginning of the 2020–2021 academic year. Nevertheless, several control measures were established to control COVID-19 transmission on the campuses. To ensure compliance with these measures, a random observational survey, based on five barrier gestures, was implemented at the University of Liege (greetings without contact, hand sanitisation, following a one-way traffic flow, wearing a mask and physical distancing). Each barrier gesture was weighted, based on experts’ elicitation, and a scoring system was developed. The results were presented as a diagram (to identify the margin of improvement for each barrier gesture) and a risk management barometer. In total, 526 h of observations were performed. The study revealed that some possible improvements could be made in the management of facilities, in terms of room allocation, the functionality of hydro-alcoholic gel dispensers, floor markings and one-way traffic flow. Compliance with the barrier gestures reached an overall weighted score of 68.2 (between 0 and 100). Three barrier gestures presented a lower implementation rate and should be addressed: the use of hydro-alcoholic gel (particularly when exiting buildings), compliance with the traffic flow and the maintenance of a 1.5 m physical distance outside of the auditoriums. The methodology and tool developed in the present study can easily be applied to other settings. They were proven to be useful in managing COVID-19, as the barometer that was developed and the outcomes of this survey enabled an improved risk assessment on campuses, and identified the critical points to be addressed in any further public health communication or education messages.

Background The role played by large-scale repetitive SARS-CoV-2 screening programs within university populations interacting continuously with an urban environment, is unknown. Our objective was to develop a model capable of predicting the dispersion of viral contamination among university populations dividing their time between social and academic environments. Methods Data was collected through real, large-scale testing developed at the University of Liège, Belgium, during the period Sept. 28th-Oct. 29th 2020. The screening, offered to students and staff (n = 30,000), began 2 weeks after the re-opening of the campus but had to be halted after 5 weeks due to an imposed general lockdown. The data was then used to feed a two-population model (University + surrounding environment) implementing a generalized susceptible-exposed-infected-removed compartmental modeling framework. Results The considered two-population model was sufficiently versatile to capture the known dynamics of the pandemic. The reproduction number was estimated to be significantly larger on campus than in the urban population, with a net difference of 0.5 in the most severe conditions. The low adhesion rate for screening (22.6% on average) and the large reproduction number meant the pandemic could not be contained. However, the weekly screening could have prevented 1393 cases (i.e. 4.6% of the university population; 95% CI: 4.4–4.8%) compared to a modeled situation without testing. Conclusion In a real life setting in a University campus, periodic screening could contribute to limiting the SARS-CoV-2 pandemic cycle but is highly dependent on its environment.

We use relative value to measure limits to arbitrage in fixed-income markets. Relative value captures apparent deviations from no-arbitrage relationships. It is simple, intuitive and can be computed model-free for any bond. A pseudo-trading strategy based on relative value generates higher returns than one based on the well-known noise measure. The relative value is therefore a better proxy for limits to arbitrage. We construct relative value indices for the US, UK, Japan, Germany, Italy, France, Switzerland and Canada. Limits to arbitrage increase with the scarcity of capital: we find that each index is correlated with local volatility and funding costs. Limits to arbitrage also exhibit strong commonality across countries, consistent with the international mobility of capital. The relative value indices are updated regularly and available publicly.

A general occurrence of the phenomenon of priming effect (PE) across varying land use and soil types has not been established so far, particularly on a large geographical scale. Moreover, the impacts of soil properties and soil organic matter (SOM) distribution among physical fractions on the magnitude of PE are still unclear. We addressed these knowledge gaps by incubating thirty five soils with or without addition of 13C labeled cellulose for 262 days. The soils were sampled from different land uses and depths of contrasting soil types from five continents (Asia, Europe, America, Australia and Africa). Results showed positive PE in all soils including grassland, cropland, forest, savannah and orchard. On average, the cumulative PE represented 27.0 ± 28.7% of the CO2 efflux in control soils and 28.48 ± 21.08% of the remaining/unrespired cellulose-C. The PE was 72.1% higher in surface than deep soils suggesting that surface soils are more prone to PE induced by cellulose addition. Variations in PE were mainly explained by soil characteristics and not by land use. We found that the PE increased with the relative abundance of SOM not associated with minerals and rich in nitrogen (N). The observation of systematic positive PE in all soils suggested that microbial co-metabolism to decompose SOM is a widespread microbial strategy. Our results also support the idea that microorganisms use co-metabolism to mine nutrients in SOM since they target N-rich fractions. However, other mechanisms are also at play since positive PE was maintained despite the high availability of mineral nutrients. Overall, PE is a worldwide process playing a major role for soil C dynamics, especially in N-rich soils.

International audience; Forty years of research on the rhizosphere priming effect (RPE) has demonstrated the potentially large increase (up to a factor 3) of soil organic matter mineralization induced by plant roots, but failed to directly quantify its contribution to the carbon (C) balance. Combining continuous CO2 flux measurements with RPE measurements has thus far been technically challenging. Here, we present an experimental platform of 40 mesocosms (volume = 88L; surface = 0.049 m2), including a 13C-labeled CO2 air-production system with a maximum capacity of 4 m3min−1 and customizable labeling intensity. For this study,13C depleted fossil C was used as source of labeled CO2 and the experiment was run for 250 days. Continuous net CO2 exchange measurements allowed us to estimate net ecosystem productivity, gross primary production and ecosystem respiration of the studied plant-soil systems. The RPE was regularly (bi-monthly to monthly) quantified by measuring the accumulation and isotopic composition of CO2 in dark chambers placed over the mesocosms. Our results show a good re- lationship between night plant-soil respiration (from continuous CO2 exchange measurements) and dark plant- soil respiration (from CO2 accumulation in dark chambers). This result suggests that our estimates of RPE and plant-soil fluxes based on the different methods are comparable. Preliminary results obtained in spring with grasses cultivated under ambient or elevated CO2 indicate that the RPE represents 1.22 ± 0.16% of gross primary production and 4.64 ± 1.12% of ecosystem respiration. The RPE estimates may have an uncertainty linked to the possible deviation in delta 13C between C sources (soil or plant) and released CO2 from these sources. We performed a sensitivity analysis on how the variation in intensity of isotopic labeling (difference in delta 13C between plant and soil) affects the uncertainty of RPE estimates considering 1‰ delta 13C deviation. Estimation of the RPE with an uncertainty lower than 10% of the estimated value requires a labeling intensity higher than 60 ‰. The developed platform will help to scale up the study of the RPE control on C cycling to the ecosystem level.

Algae are the basis of primary production in aquatic ecosystems. The onset of food production in a aquatic environment begins with these organisms and with a complex mechanism called photosynthesis...

In order to control the COVID-19 pandemic, barrier gestures were used to reduce the transmission of the virus within a community and avoid large peaks of infections with the risk of overwhelming the healthcare systems. The acceptability of these measures is the backbone of their successful implementation. However, population compliance with these measures within a community is uncertain, even when mandatory. At the beginning of the 2020-2021 academic year, the University of Liege complemented these measures, by organizing a weekly screening by saliva testing on a voluntary basis for all its workers and students. Their compliance with the different measures was necessary for effective control program and an intensive communication plan was implemented throughout the 2020-2021 academic year for that purpose METHOD AND PRINCIPAL FINDINGS: An online survey was launched upon the implementation of the saliva testing in order (i) to assess the level of acceptance of the different measures by the university workers and students and (ii) to identify the factors determining their acceptance (based on the Health Belief Model) and their reported level of implementation. A total of 921 responses was received and analysed by sub-group comparison, structural equation modelling and multivariable ordinal logistic regression. Health motivation, susceptibility, severity and perception of benefits were identified as the key determinants of protective measures acceptance CONCLUSION AND SIGNIFICANCE: In order to influence positively these mental constructs and to increase the level of implementation of control measures, it is therefore recommended to raise the awareness of the university workers and students about their self and collective responsibility to protect themselves and the population at risk that can be severely affected by the disease. The non-medical faculties (i.e. the Faculty of Medicine and the Faculty of Veterinary Medicine excluded) should be specifically targeted as their heath motivation was significantly lower. This survey demonstrates that the risk mitigation strategies against COVID-19 should integrate the importance of individual perception. The methodology developed in this survey can be generalised in space and time, in different contexts.

Altres ajuts: these projects are co-funded by European regional development fund (ERDF / FEDER, 2007-2013). Recent studies suggest that carbon (C) is stored in the topsoil of pastures established after deforestation. However, little is known about the long-term capacity of tropical pastures to sequester C in different soil layers after deforestation. Deep soil layers are generally not taken into consideration or are underestimated when C storage is calculated. Here we show that in French Guiana, the C stored in the deep soil layers contributes significantly to C stocks down to a depth of 100 cm and that C is sequestered in recalcitrant soil organic matter in the soil below a depth of 20 cm. The contribution of the 50-100 cm soil layer increased from 22 to 31 % with the age of the pasture. We show that long-term C sequestration in C4 tropical pastures is linked to the development of C3 species (legumes and shrubs), which increase both inputs of N into the ecosystem and the C:N ratio of soil organic matter. The deep soil under old pastures contained more C3 carbon than the native forest. If C sequestration in the deep soil is taken into account, our results suggest that the soil C stock in pastures in Amazonia would be higher with sustainable pasture management, in particular by promoting the development of legumes already in place and by introducing new species.

The Federal Reserve target rate has a lower bound. Changes to the target rate occur with discrete increments. Using out-of-sample forecasts of the target rate, we evaluate models incorporating these two realistic non-linear features. Incorporating these features mitigates in-sample over-fitting and improves out-of-sample forecast accuracy of the target rate level and volatility. A model with these features performs better relative to the linear models because (i) it produces stronger responses of forecasts to inflation and unemployment and a weaker response to lagged target rate, and because (ii) it yields very different forecast distributions when the target rate is close to the lower bound.

International audience; Purpose: Germline mutations in genes encoding succinate dehydrogenase (SDH) are frequent in patients with pheochromocytoma and paraganglioma (PPGL). They lead to SDH inactivation, mediating a massive accumulation of succinate, which constitutes a highly specific biomarker of SDHx-mutated tumors when measured in vitro. In a recent pilot study, we showed that magnetic resonance spectroscopy (1H-MRS) optimized for succinate detection (SUCCES) could detect succinate in vivo in both allografted mouse models and PPGL patients. The objective of this study was to prospectively assess the diagnostic performances of 1H-MRS SUCCES sequence for the identification of SDH deficiency in PPGL patients.Methods: Forty-nine patients presenting with 50 PPGLs were prospectively enrolled in our referral center for 1H-MRS SUCCES. Two observers blinded to the clinical characteristics and genetic status analyzed the presence of a succinate peak and confronted the results to a composite gold standard combining PPGL genetic testing and/or in vitro protein analyses in the tumor.Results: A succinate peak was observed in 20 tumors, all of which had proven SDH deficiency using the gold standard (17 patients with germline SDHx mutations, 2 with a somatic SDHD mutation, and 1 with negative SDHB IHC and SDH loss of function). A false negative result was observed in 3 tumors. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of 1H-MRS SUCCES were respectively 87%, 100%, 100%, 90%, and 94%.Conclusions: Detection of succinate using 1H-MRS is a highly specific and sensitive hallmark of SDH-deficiency in PPGLs.

Germline mutations in genes encoding succinate dehydrogenase (SDH) are frequent in patients with pheochromocytoma and paraganglioma (PPGL). They lead to SDH inactivation, mediating a massive accumulation of succinate, which constitutes a highly specific biomarker of SDHx-mutated tumors when measured in vitro. In a recent pilot study, we showed that magnetic resonance spectroscopy (Forty-nine patients presenting with 50 PPGLs were prospectively enrolled in our referral center forA succinate peak was observed in 20 tumors, all of which had proven SDH deficiency using the gold standard (17 patients with germline SDHx mutations, 2 with a somatic SDHD mutation, and 1 with negative SDHB IHC and SDH loss of function). A false negative result was observed in 3 tumors. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy ofDetection of succinate using

International audience; Positioning a person or an object has become essential in many applications. It already exists solutions for outdoor positioning such as satellite based techniques (i.e. GPS) but indoor positioning still remains a great challenge for applications like sports monitoring, contextual visits of museum, Building Information Modeling (BIM) or automated drone missions. Classical approaches using radio communication such as WiFi, Bluetooth, ZigBee only give an accuracy of approximately 2.5 meters when the mobile is static, of course worse when moving. Recently some new radio communication chipsets have emerged based on Ultra Wide Band (UWB) communications. UWB allows accurate Time Of Flight (TOF) measurements, and thus distances estimations between nodes equipped with. A positioning algorithm named Best Anchor Selection for Trilateration (BAST) based on position prediction and noise estimation is proposed. Then a wearable, light and low power Wireless Sensor Network (WSN) prototype (named Zyggie) including an UWB chipset has been developed for algorithms comparison. Finally, an experimental testbed using real cases experiments shows that BAST can give from 1.26 up to 4.17 times better accuracy than low complexity state of the art algorithms when the mobile/person is in movement (e.g. tennis player).

The Homoscedastic Gamma (HG) model characterizes the distribution of returns by its mean, variance and an independent skewness parameter. The HG model preserves the parsimony and the closed form of the Black–Scholes–Merton (BSM) while introducing the implied volatility (IV) and skewness surface. Varying the skewness parameter of the HG model can restore the symmetry of IV curves. Practitioner’s variants of the HG model improve pricing (in-sample and out-of-sample) and hedging performances relative to practitioners’ BSM models, with as many or less parameters. The pattern of improvements in Delta-Hedged gains across strike prices accord with predictions from the HG model. These results imply that expanding around the Gaussian density does not offer sufficient flexibility to match the skewness implicit in options. Consistent with the model, we also find that conditioning on implied skewness increases the predictive power of the volatility spread for excess returns.

De maniere generale, le concept de citoyennete a considerablement evolue. En ce qui concerne le handicap, le passage d’un modele medical a un modele social et ensuite a un point de vue psychosocial et pluridisci-plinaire a transforme les modalites d’intervention. Les personnes en situation de handicap de beneficiaires-usagers sont devenues des beneficiaires-experts, socialement incluses plutot qu’inserees. Une justice sociale reellement inclusive ne peut s’instaurer qu’a travers des processus d’apprentissages de l’ensemble des personnes concernees, usagers, professionnels, chercheurs, experts, politiques.

Etre citoyen, c’est beneficier des apports des technologies de l’information et de la communication (TIC), mais c’est aussi etre capable de les maitriser comme outil d’expression et de communication sociale et de lutte contre la fracture numerique notamment dans le champ du handicap. Ces technologies peuvent servir soit d’outils pour la readaptation fonctionnelle, soit d’outils d’expression pour les personnes ayant des difficultes cognitives, soit d’outils d’expression d’opinions pour les personnes tributaires de deficience sensorielle.

International audience; Understanding autotrophic (Ra) and heterotrophic (Rh) components of soil respiration (Rs) and their temperature sensitivity (Q(10)) is critical for predictingsoil carbon (C) cycle and its feedback to climate change. In agricultural systems, these processes can be considerably altered by chemical fertilizer and compost application due to changes in nitrogen (N) supply and substrate quality (decomposability). We conducted a field experiment including control, urea, and four compost treatments. Ra and Rh were separated using the root exclusion method. Composts were characterized by chemical analyses, C-13 solid-state nuclear magnetic resonance, and lignin monomers. Annual cumulative Ra, along with root biomass, increased with soil mineral N, while Rh was suppressed by excessive N supply. Thus, Ra was stimulated but Rh was decreased by urea alone application. Annual Rh was increased by application of compost, especially that containing most lignin vanillyl and syringyl units, O-alkyl C, di-O-alkyl C, and manganese. However, during the initial period, Rh was most effectively stimulated by the compost containing most carbohydrates, lignin cinnamyl units, phenolic C, and calcium. Ra was mediated by N release from compost decomposition and thus exhibited similar responses to compost quality as Rh. The Rh Q(10) was reduced, while Ra Q(10)was increased by chemical fertilizer and compost application. Moreover, the Rh Q(10) negatively related to soil mineral N supply and compost indicators referring to high substrate quality. Overall, our results suggest that N supply and substrate quality played an important role in regulating soil C flux and its response to climate warming.

Does the macroeconomic information in data releases shape bond yields in the long-term? We offer evidence that the new information embedded in high-frequency bond price changes around the release of economic data explains at most 40% of yields fluctuations at longer horizons, and as low as 20% in the long run. From the perspective of a theoretical model in which investors learn from the releases about the path of future short rates, our empirical findings suggest that investors’ expectations about future monetary policy actions are updated largely based on information revealed outside of the releases. Our results cast doubts on a transparent monetary policy response function linking macroeconomic surprises to the path of interest rates.

The plant economics spectrum is increasingly recognized as a major determinant of plant species effects on terrestrial ecosystem functioning related to carbon cycling. However, the role of plant economic strategies in the effects of living root activity on soil organic carbon (SOC) dynamics through rhizodeposition remains unexplored, despite SOC being the largest terrestrial carbon pool. Using a continuous C-13-labelling method allowing partitioning of plant and soil sources to carbon fluxes and pools, we studied here the linkages between plant economic strategies and SOC cycling processes in a 'common garden' greenhouse experiment. It includes a panel of 12 grassland species selected along a gradient of economic traits and belonging to three functionnal groups (C3 grasses, forbs and legumes). All species induced an acceleration of native SOC mineralization but this rhizosphere priming effect (RPE) substantially differed across species and varied eleven-fold by the end of the experiment (from +26% to +295% relative to unplanted soil). Interspecific variation in RPE was primarily linked to plant photosynthetic activity associated to species economic strategies of light and CO2 resource acquisition and processing. Fast-growing acquisitive species, such as legumes, featured large RPE, in relation with their high canopy photosynthesis coupled to high leaf photosynthetic capacity and large net primary productivity allocated above-ground. This large RPE was further associated with high root metabolic activity, rhizodeposition and soil microbial activity. In contrast, fine-root growth and economic traits related to soil resource foraging ability were poor predictors of RPE. The formation of new root-derived SOC varied nine-fold across species and was similarly positively related to the net primary productivity allocated above-ground. Fast-growing acquisitive species with a high photosynthetic activity induced a disproportionately large RPE relative to SOC formation. Synthesis. Overall, our study demonstrates that rhizodeposition is a major mechanism through which plant economic strategies of grassland species control soil carbon dynamics. Acquisitive versus conservative species were associated with high versus low rates of photosynthesis and rhizodeposition, in turn leading to fast versus slow SOC turnover. This emphasizes the importance of considering rhizosphere processes for understanding plant species effects on soil biogeochemistry.

Southwest Siberia encompasses the forest-steppe and sub-taiga climatic zones and has historically been utilized for agriculture. Coinciding with predicted changes in climate for the region is the pressure of agricultural development; however, a characterization of the soil water and carbon dynamics is lacking. We assessed current soil water properties and soil organic carbon turnover in forests and grasslands for two sites that span the forest steppe and sub-taiga bioclimatic zones. Soil evaporation was 0.62 ± 0.17 mm d−1 (mean ± standard error) in grasslands and 0.45 ± 0.08 mm d−1 in the forests of the forest-steppe site. Evaporation at the sub-taiga site was 1.80 ± 1.70 mm d−1 in grasslands and 0.96 ± 0.05 mm d−1 in forest plots. Evaporation was significantly greater at the sub-taiga site than the forest-steppe site. The density of fine roots explained the soil water isotopic patterns between vegetation types and sites. We found soil organic matter turnover to be three times faster in the sub-taiga site than in the forest-steppe site. Our results show that while climate factors, in particular snow levels, between the two sites are drivers for water and carbon cycles, site level hydrology, soil characteristics, and vegetation directly interact to influence the water and carbon dynamics.

An emerging literature relies on an index of limits of arbitrage in fixed-income markets. We analyze the benefits of an index that is model-free, robust and intuitive. This new index strengthens the evidence that limits of arbitrage proxy for risks priced in the cross-section of returns. Trading simulations show that the new index improves identification of limits of arbitrage because it bypasses a noisy estimation step. Relative value indices in the US, the UK, Japan, Germany, Italy, France, Switzerland and Canada exhibit strong commonality and high correlations with local volatility and funding conditions. The indices are updated regularly and available publicly.

International audience; Most current models of soil C dynamics predict that climate warming will accelerate soil C mineralization, resulting in a long-term CO2 release and positive feedback to global warming. However, ecosystem warming experiments show that CO2 loss from warmed soils declines to control levels within a few years. Here, we explore the temperature dependence of enzymatic conversion of polymerized soil organic C (SOC) into assimilable compounds, which is presumed the rate-limiting step of SOC mineralization. Combining literature review, modelling and enzyme assays, we stud-ied the effect of temperature on activity of enzymes considering their thermal inactivation and catalytic activity. We defined the catalytic power of enzymes (Epower) as the cumulative amount of degraded substrate by one unit of enzyme until its complete inactivation. We show a universal pattern of enzyme’s thermodynamic properties: activation energy of catalytic activity (EAcat) activation energy of ther-mal inactivation (EA inact). By investing in stable enzymes (high EA inact) having high catalytic activity (low EA cat), microorganisms may maximize the E power of their enzymes. The counterpart of such EAs ’hierarchical pattern is the higher relative temperature sensitivity of enzyme inactivation than catalysis, resulting in a reduction in Epower under warming. Our findings could explain the decrease with temperature in soil enzyme pools, microbial biomass (MB) and carbon use efficiency (CUE) reported in some warming experiments and studies monitoring the seasonal variation in soil enzymes. They also suggest that a decrease in soil enzyme pools due to their faster inactivation under warming contributes to the observed attenuation of warming effect on soil C mineralization. This testable theory predicts that the ultimate response of SOC degradation to warming can be positive or negative depending on the relative temperature response of E power and microbial production of enzymes.

International audience; First of all, we recall that the message conveyed in our paper is that Amazonian forest and old tropical pastures act as C sinks by accumulating recurrently (continuously) C in biomass and soil. We do not support the idea that deforestation increases soil C as suggested in the title of Schipper and Smith comment. In our study, pasture C sink was estimated by two independent methods: eddy covariance measurements (Eddy) and a 36-years chronosequence analyzing soil organic C stock to a depth of 100 cm (Chrono). Both methods provide evidence that pastures ≥24 years can restore all or part of C sink of Amazonian forest if sustainable management is applied. Realizing that old pastures accumulate C is crucial in the Amazonian context where pastures are currently replaced by intensive crops (e.g. soybean) inducing a possible loss of this C sink.

Agricultural management practices including soil tillage exert strong control on soil organic matter (SOM) turnover and its interactions with global C cycle through different mechanisms. One control mechanism is the priming effect (PE) which consists in stimulating SOM mineralization with the addition of fresh, energetic plant material. In this study, we quantified C mineralization and PE in soils sampled in two contrasted long-term (40 years) tillage treatments which deeply modified soil properties (e.g. organic C concentration, microbial biomass, pH). We hypothesized that soil tillage might affect these processes through changes in C addition rates, nutrient availability, and long-term variations in SOM content and microbial communities. We investigated the relationship between PE intensity, tillage and nutrients availability in soil samples taken in no till (NT) and full inversion tillage (FIT) in two layers (0–5 and 15–20 cm). Soils were incubated with or without addition of 13 C labeled cellulose and mineral nutrients. Potential C mineralization and primed C were measured during 262 days. Unlabeled soil microbial biomass C was determined at the end of the experiment to separate apparent and real priming effect. Basal cumulative C mineralization in the control soil ranged from 363 to 1490 mg kg −1 soil at day 262. It was strongly correlated with soil organic carbon (SOC) concentration. Specific mineralization rates were 44.8 and 68.8 g kg −1 SOC in the 0–5 cm layer for the FIT and NT treatments, respectively and were strongly linked with the particulate organic matter content ( r = 0.99***). These results suggest that SOC was more active in the upper layer of the NT treatment due to the high concentration of readily-decomposable, particulate organic matter. The cellulose was entirely metabolized after 60 days and its kinetics of mineralization was affected neither by tillage, depth nor nutrients. The percentage of cellulose C released as CO 2 represented 55–61% of the added cellulose-C at day 262. A positive PE was found in all treatments and its kinetics was parallel to that of cellulose mineralization. The cumulative PE significantly varied with nutrients level but not tillage, ranging from 73 to 78 mg kg −1 under high nutrients level and from 116 to 136 mg kg −1 in low nutrients level. No significant differences were found in unlabeled microbial biomass C between control and amended soil, suggesting no apparent priming effect. We conclude that the priming was mainly controlled by nutrient availability but not tillage, in spite of strong tillage-induced changes in SOC concentration and microbial biomass. Since PE is known to depend on C addition rate, tillage is expected to affect in situ PE through variations in the ratio of fresh carbon to nutrient concentration along the soil profile.

Standard Gaussian term structure models impose the Markov property: the conditional mean is a function of the risk factors. We relax this assumption and consider models where yields are linear in the conditional mean (but not in the risk factors). To illustrate, yields should span expected inflation but not inflation. Second, expected and surprise yield changes can have opposite contemporaneous effects on expected inflation. Third, the survey forecasts and inflation rate can both be in the state. These three features are inconsistent with the Markov assumption. These effects matter empirically in the USA and in Canada.

The respiratory release of CO2 from soils is a major determinant of the global carbon cycle. It is traditionally considered that this respiration is an intracellular metabolism consisting of complex biochemical reactions carried out by numerous enzymes and co-factors. Here we show that the endoenzymes released from dead organisms are stabilised in soils and have access to suitable substrates and co-factors to permit function. These enzymes reconstitute an extracellular oxidative metabolism (EXOMET) that may substantially contribute to soil respiration (16 to 48% of CO2 released from soils in the present study). EXOMET and respiration from living organisms should be considered separately when studying effects of environmental factors on the C cycle because EXOMET shows specific properties such as resistance to high temperature and toxic compounds.