Completion Dissection or Observation for Sentinel-Node Metastasis in Melanoma.

Sentinel-lymph-node biopsy is associated with increased melanoma-specific survival (i.e., survival until death from melanoma) among patients with node-positive intermediate-thickness melanomas (1.2 to 3.5 mm). The value of completion lymph-node dissection for patients with sentinel-node metastases is not clear. In an international trial, we randomly assigned patients with sentinel-node metastases detected by means of standard pathological assessment or a multimarker molecular assay to immediate completion lymph-node dissection (dissection group) or nodal observation with ultrasonography (observation group). The primary end point was melanoma-specific survival. Secondary end points included disease-free survival and the cumulative rate of nonsentinel-node metastasis. Immediate completion lymph-node dissection was not associated with increased melanoma-specific survival among 1934 patients with data that could be evaluated in an intention-to-treat analysis or among 1755 patients in the per-protocol analysis. In the per-protocol analysis, the mean (±SE) 3-year rate of melanoma-specific survival was similar in the dissection group and the observation group (86±1.3% and 86±1.2%, respectively; P=0.42 by the log-rank test) at a median follow-up of 43 months. The rate of disease-free survival was slightly higher in the dissection group than in the observation group (68±1.7% and 63±1.7%, respectively; P=0.05 by the log-rank test) at 3 years, based on an increased rate of disease control in the regional nodes at 3 years (92±1.0% vs. 77±1.5%; P<0.001 by the log-rank test); these results must be interpreted with caution. Nonsentinel-node metastases, identified in 11.5% of the patients in the dissection group, were a strong, independent prognostic factor for recurrence (hazard ratio, 1.78; P=0.005). Lymphedema was observed in 24.1% of the patients in the dissection group and in 6.3% of those in the observation group. Immediate completion lymph-node dissection increased the rate of regional disease control and provided prognostic information but did not increase melanoma-specific survival among patients with melanoma and sentinel-node metastases. (Funded by the National Cancer Institute and others; MSLT-II ClinicalTrials.gov number, NCT00297895 .)

Action Neige 2016-2017: Amélioration de la modélisation hydrologique distribuée en conditions naturelles dans les Alpes

[Departement_IRSTEA]Eaux [TR1_IRSTEA]ARCEAU [ADD1_IRSTEA]Hydrosystèmes et risques naturelsCe rapport présente le travail d'amélioration de la modélisation hydrologique distribuée J2000 (modèle J2000-Rhône) dans les Alpes où la composante nivale est importante. Les travaux ont porté sur le test et la sélection de forçages météorologiques adaptés (SAFRAN, SPAZM), l'amélioration de la composante Neige du modèle, et la sensibilité au raffinement du maillage, en réalisant des tests sur des jeux de 32 à 3 sous-bassins. Le projet propose une version optimisée de la paramétrisation de J2000 quant aux processus liés à la neige (partition pluie-neige des précipitations, accumulation, fonte)

Blowing snow sublimation at high altitude and effects on the surface boundary layer,

International audienceIn alpine terrain, wind-induced snow transport strongly influences the spatial and temporal variability of the snow cover. During their transport, blown snow particles undergo sublimation with an intensity depending on atmospheric conditions (air temperature and humidity). The mass loss due to blowing snow sublimation is a source of uncertainty for the mass balance of the alpine snowpack. Additionally, blowing snow sublimation modifies humidity and temperature in the surface boundary layer. To better quantify these effects in alpine terrain, a dedicated measurement setup has been deployed at the experimental site of Col du Lac Blanc (2720 m a.s.l., French Alps, Cryobs-Clim network) since winter 2015/2016. It consists in three vertical masts measuring the near-surface vertical profiles (0.2-5 m) of wind speed, air temperature and humidity and blowing snow fluxes and size distribution. Observations collected during blowing snow events without concurrent snowfall show only a slight increase in relative humidity (10-20%) and near-surface saturation is never observed. Estimation of blowing snow sublimation rates are then obtained from these measurements. They range between 0 and 5 mmSWE day-1 for blowing snow events without snowfall in agreement with previous studies in different environments (North American prairies, Antarctica). Finally, an estimation of the mass loss due to blowing snow sublimation at our experimental site is proposed for two consecutive winters. Future use of the database collected in this study includes the evaluation of blowing snow models in alpine terrain

Paramétrage de l'interception de la neige par le couvert forestier

International audienceSnow interception drives spatial heterogeneity of snow under forest canopies and displays significant differencesbetween forested, open and alpine areas at a variety of scales. Beyond giving a first order control on snow accu-mulation, interception by canopy drives other processes. A prime example is canopy albedo, as large differencesare readily visible between forest canopy albedo with and without intercepted snow. As such a correct parameteri-zation of interception is necessary as it drives many physical processes important for snow hydrology, climatologyand meteorology studies. However, current parameterizations of snow interception have not always beenable to preserve the large variance of snow beneath canopies at all scales. Various snow interception parameter-izations are applied in land surface models but are generally not validated for different snow climates and/or scales.Here, we developed parameterizations for spatial mean and standard deviation of interception over horizon-tal scales of 50 m. They were developed from a comparison of (1) computed forest structure metrics (sky viewfactor and standard deviation) from a high-resolution Lidar derived digital terrain model and (2) an existingdataset of several thousand interception measurements collected after nine storm events in a coniferous forest inthe Eastern Swiss Alps. By scaling open area snow precipitation with the calculated forest structure metrics, wecomputed spatial mean and standard deviation of forest canopy interception. We obtained similar performancestatistics compared to previously suggested parameterizations, i.e. a RMSE of 1.3 cm (1 mm SWE) for spatialmean and 0.6 cm (0.4 mm SWE) for the standard deviation of canopy interception.Furthermore, we then validated both new interception parameterizations with data from two different geo-graphic regions and snow climates, namely from a study site in Utah, U.S. and one in the French Alps. Thiscomparison suggests that our sub-grid parameterizations for snow interception are applicable in models to describesnow depth heterogeneities for different snow climates and mountain forest environment