Temporal integration of soil N2O fluxes: validation of IPNOA station automatic chamber prototype.

The assessment of nitrous oxide (N2O) fluxes from agricultural soil surfaces still poses a major challenge to the scientific community. The evaluations of integrated soil fluxes of N2O are difficult owing to their lower emissions when compared with CO2. These emissions are also sporadic as environmental conditions act as a limiting factor. A station prototype was developed to integrate annual N2O and CO2 emissions using an automatic chamber technique and infrared spectrometers within the LIFE project (IPNOA: LIFE11 ENV/IT/00032). It was installed from June 2014 to October 2015 in an experimental maize field in Tuscany. The detection limits for the fluxes were evaluated up to 1.6 ng N-N2O m2 s-1 and 0.3 µg C-CO2 m2 s-1. A cross-comparison carried out in September 2015 with the "mobile IPNOA prototype"; a high-sensibility transportable instrument already validated provided evidence of very similar values and highlighted flux assessment limitations according to the gas analyzers used. The permanent monitoring device showed that temporal distribution of N2O fluxes can be very large and discontinuous over short periods of less than 10 days and that N2O fluxes were below the detection limit of the instrumentation during approximately 70% of the measurement time. The N2O emission factors were estimated to 1.9% in 2014 and 1.7% in 2015, within the range of IPCC assessments.

High-resolution inventory of NO emissions from agricultural soils over the Ile-de-France region.

Arable soils are a significant source of nitric oxide (NO), a precursor of tropospheric ozone, and thereby contribute to ozone pollution. However, their actual impact on ozone formation is strongly related to their spatial and temporal emission patterns, which warrant high-resolution estimates. Here, we combined an agro-ecosystem model and geo-referenced databases to map these sources over the 12,000 km2 administrative region surrounding Paris, France, with a kilometric level resolution. The six most frequent arable crop species were simulated, with emission rates ranging from 1.4 kg N-NO ha(-1) yr(-1) to 11.1 kg N-NO ha(-1) yr(-1). The overall emission factor for fertilizer-derived NO emissions was 1.7%, while background emissions contributed half of the total NO efflux. Emissions were strongly seasonal, being highest in spring due to fertilizer inputs. They were mostly sensitive to soil type, crops' growing season and fertilizer N rates.

Challenges in quantifying biosphere-atmosphere exchange of nitrogen species.

Recent research in nitrogen exchange with the atmosphere has separated research communities according to N form. The integrated perspective needed to quantify the net effect of N on greenhouse-gas balance is being addressed by the NitroEurope Integrated Project (NEU). Recent advances have depended on improved methodologies, while ongoing challenges include gas-aerosol interactions, organic nitrogen and N(2) fluxes. The NEU strategy applies a 3-tier Flux Network together with a Manipulation Network of global-change experiments, linked by common protocols to facilitate model application. Substantial progress has been made in modelling N fluxes, especially for N(2)O, NO and bi-directional NH(3) exchange. Landscape analysis represents an emerging challenge to address the spatial interactions between farms, fields, ecosystems, catchments and air dispersion/deposition. European up-scaling of N fluxes is highly uncertain and a key priority is for better data on agricultural practices. Finally, attention is needed to develop N flux verification procedures to assess compliance with international protocols.

Episodic memory in transient global amnesia: encoding, storage, or retrieval deficit?

OBJECTIVES: To assess episodic memory (especially anterograde amnesia) during the acute phase of transient global amnesia to differentiate an encoding, a storage, or a retrieval deficit. METHODS: In three patients, whose amnestic episode fulfilled all current criteria for transient global amnesia, a neuropsychological protocol was administered which included a word learning task derived from the Grober and Buschke's procedure. RESULTS: In one patient, the results suggested an encoding deficit, and in two others, a storage deficit. CONCLUSIONS: The encoding/storage impairment concerning anterograde amnesia documented in our patients stands in clear contrast with the impairment in retrieval which must underly the retrograde amnesia that also characterises transient global amnesia. This dissociation in turn favours the idea of a functional independence among the cognitive mechanisms that subserve episodic memory.

Dose-effect study of intranasal administration of growth hormone-releasing hormone-44-NH2 in healthy subjects.

Intranasal (in) administration of GH-releasing hormone-40- (GHRH-40) has been demonstrated to be efficient in stimulating GH secretion at doses equal to or higher than 30 micrograms/kg in man. We performed a dose-response study with GHRH-44-NH2 (GHRH) given by nasal spray and closely monitored local tolerance. Twelve normal young men were given 5 GNRH doses (125, 250, 500, 750, and 1000 micrograms) and placebo in random order according to a latin square design. Mild symptoms of local intolerance, subjective, objective, or both, were noted in the first 20 min after spray in 30 of 72 tests, and a significant difference (P = 0.003) was obtained in their frequency between the group placebo plus the lowest dose and the group of the other doses. The areas under the GH curves were significantly different between the subjects and the doses (by analysis of variance, P = 0.001 and P = 0.025, respectively). Multiple comparison tests showed a significant difference between the 3 highest doses and the placebo (P = 0.005, P = 0.05, and P = 0.02, respectively) and a significant difference between the highest dose and the 2 lowest doses (P = 0.005). By weighted linear regression between GH areas under the curve and GHRH doses the dose-response relationship was established as: y = 1.226x + 457. The magnitude of the GH peaks induced by in GHRH was significantly lower than that induced by iv GHRH. We conclude that in the normal young men tested, who were high responders to GHRH (as demonstrated by iv test), a 500-micrograms dose is sufficient to elicit GH secretion. Local tolerance, although imperfect, appears satisfactory to permit a clinical trial in children.