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Many seasonally stratified lakes accumulate substantial amounts of the greenhouse gas methane in the anoxic zone. Methane oxidizing bacteria in the water column act as a converter, oxidizing methane into carbon dioxide and biomass before it reaches the atmosphere. Current observations and estimates of this methane oxidation efficiency are diverging, especially for the lake overturn period. Here we combine a model of turbulent mixing, gas exchange and microbial growth with a comprehensive data set for autumn mixing to quantify the relevant physical and microbial processes. We show that the microbial methane converter is effectively transforming the increased methane flux during the overturn period. Only rare events of pronounced surface cooling in combination with persistently strong wind can trigger substantial outgassing. In the context of climate change, these results suggest that changes in the frequency of storms may be even more important for methane emissions from temperate lakes than gradual warming.

International audience; Context : In 2000, the European Parliament set out a framework (European Water Framework Directive) for managing and protecting water bodies in Europe. Classification of water bodies into «ecological status» is a key issue for the implementation of that framework. For lakes, the assessment of this status is based on biological (e.g . fish, phytoplankton and macrophyte), physical-chemical and hydro-morphological indicators. The physical-chemical and phytoplankton indicators are based on 4 observations given by integrated samples over the growing season during one year for a 6 years management plan. The sampling occur in the euphotic zone over the deepest point of the lake. However, in large lakes, ecological parameters, used for water quality assessment (e.g . chlorophyll-a concentration and Secchi depth), exhibit strong spatial-temporal heterogeneities. Consequently, the representativeness of those data versus the whole lake might be questionable and needs to be verified (Kiefer et al., 2015). The objective is to evaluate how spatial and temporal heterogeneities in chlorophyll-a may impact the assessment of Lake Geneva ecological status; we propose to combine remote sensing data and 3D modelling

Studies on melanoma cell lines indicate the expression of actin-binding protein (ABP), a peripheral cytoplasmic protein that crosslinks actin, is important for melanoma cell motility. We used an ABP-specific monoclonal antibody to characterize ABP expression in 18 benign nevi and 28 primary and metastatic malignant melanomas. Heterogeneous expression of ABP staining was observed in metastatic melanoma. No clear differences in ABP staining were identified among compound nevi, dysplastic nevi, and superficial spreading melanoma; however, the lentiginous intraepidermal component of the benign and malignant lesions and the pagetoid cells of superficial spreading malignant melanoma were negative for ABP. In contrast, the nested intraepidermal and dermal components of both benign nevi and primary malignant melanoma were positive. The differential expression of ABP of the lentiginous component as opposed to the intraepidermal nests and pagetoid cells of benign nevi or melanoma may represent a capacity of the nested melanocytes to migrate from the epidermis to the dermis during maturation or invasion. Taken together, the findings support that ABP may be important for cell-cell adhesion during tumorigenesis and may play a role in tumor cell ameboid motility during tissue invasion.

We report a case of primary cutaneous melanoma with the incidental finding of a lung metastasis 27 years following the original diagnosis. The case is exceptional in that it is a late metastasis of a melanoma that arose in association with a halo giant congenital nevus. The original tumor was a large dermal/subcutaneous nodule composed of very well-differentiated cells reminiscent of type B nevomelanocytes. The metastasis displayed similar histology. This case emphasizes the unpredictable behavior of malignant melanoma. In cases with 'unusual' histology such as this one, the usual prognostic parameters are less helpful in predicting survival. Melanoma should be included in the differential diagnosis of an undiagnosed lesion suspicious for metastasis even if the primary was removed in the remote past.

Background. Cutaneous manifestations of myeloid leukemia can be specific or nonspecific. The study was designed to determine the prevalence and histologic appearance of cutaneous lesions in patients with myeloid leukemia and various myeloproliferative disorders. Methods. The histologic changes of cutaneous lesions in 52 patients with myelodysplastic syndrome, polycythemia vera, and myeloid, myelomonocytic, or monocytic leukemia are presented in this study. Results. Two types of cellular infiltrates were identified. In the first group, the most common pattern was a diffuse involvement by the leukemic cells through the entire dermis with preservation of a “grenz zone” in the superficial dermis. Two cases exhibited a Kaposi's sarcoma-like pattern, with prominent slit-like blood-filled spaces lined by myeloblasts against a fibrocellular stroma. The second group of lesions was characterized by dense, neutrophilic dermal infiltrates resembling acute neutrophilic dermatosis (Sweet's syndrome) or pyoderma gangrenosum. In two of these cases, scattered immature blast cells admixed with the mature neutrophilic elements were identified. Conclusions. Awareness of these different morphologic features and application of special stains are of value in the evaluation of suspicious cutaneous infiltrates in patients with myeloid leukemia and various myeloproliferative disorders.

REPORT OF A CASE A 65-year-old Russian woman presented with the complaint of an itchy, atraumatic, slowly growing verrucous plaque on her left lower extremity. The patient stated that the lesion had been excised three times over a period of ''many'' years in Russia and always recurred. To eliminate the pruritus, she had applied a midpotency topical steroid with no apparent benefit. On physical examination, the patient appeared healthy. She had bilateral lower extremity pitting edema (1+) to the ankles and prominent varicose veins. On her left midshin, there was an approximately 6×5-cm irregular, brown verrucous plaque arising from a well-defined, erythematous base (Figure 1). There were a few hemorrhagic crusts. The lesion appeared to arise along several surgical scars and was nontender, slightly firm, and minimally scaly. There was a smaller lesion detected proximally on the left superior thigh. There was no hepatosplenomegaly or adenopathy. A complete blood cell

Introduction-Thermal pollution can have considerable influence on water temperature in freshwater systems notably affecting stratification [Kirillin et al., 2013]. Consequences can be seen across the entire aquatic food web [Barnett, 1971; Cairns, 1971; Sylvester, 1972]. The increased usage of aquatic systems as sinks and sources of heat necessitates detailed investigations of the impact of thermal pollution on lakes and reservoirs. Here we investigate the impact of thermal pollution on temperature and heat fluxes in the perialpine Lake Biel (7°10’E, 47°5’N, 39.3 km2 and 74 m deep). The lake has a short hydraulic residence time of only 58 days and is under strong influence of the Aare tributary. The source of the thermal pollution, the Mühleberg Nuclear Power Plant, is located 20 km upstream. The plant emits 700 MW (18 W m-2) as cooling water into the Aare River. The aim of our study is to provide guidelines regarding model selection for studies of thermal pollution in similar aquatic systems. Materials and methods-The thermal consequences for Lake Biel was investigated with two hydrodynamic models. The one-dimensional model SIMSTRAT [Goudsmit et al., 2002] and the three-dimensional model Delft3D-Flow . The power plant is up for decommissioning scheduled for 2019. The influence of thermal pollution was therefore investigated by running the models with and without thermal emission. The temporal variability of the lake was analyzed for a cold (April to March 2010/2011) and a warm period (April to March 2013/2014). Results and discussion- We observe a strong seasonal dependence in the lakes response to thermal pollution. By removing the thermal pollution the lake cools down by ~ -0.3 °C between October and March. The corresponding value from April to September was ~ -0.1 °C. The impact was marginally stronger for the warm period compared to the cold period. The majority of thermal pollution (~60 %) leaves the lake through the Aare outflow. This is due to the lake’s short retention time and the short distance between the Aare inflow and outflow (~8 km). Surprisingly we were able to reproduce this throughflow accurately even with the one-dimensional model. The reason being the high discharge of the Aare which quickly flushes the incoming heat out of the lake. The flushing was likewise observed in the three- dimensional model. This model could furthermore resolve the path of the river intrusion within the lake. We could identify periods where the river water travelled along the shoreline directly from the inflow to the outflow, thereby short-cutting the lake. Additionally the spatial impact of thermal pollution was, as expected, better resolved by the three- dimensional model. With observed temperature fluctuations up to –3.4 °C in Delft3D-Flow and –1.7 °C in SIMSTRAT. We argue that three-dimensional models should be used to assess the spatial impact of extreme levels of thermal pollution, which can have severe impact on biota. For overall system assessment one-dimensional models are sufficient. However, care is required for aquatic systems with short distance between the thermal source input and outflow.

Vertical flux of oxygen in lakes can play an important role in regulating the severity of hypoxia. Direct measurement of oxygen flux has remained hard due to lack of sufficient data. In this research, we focus on measuring vertical oxygen flux in a small hypoxic Canadian Shield lake using Fick’s Law = −K dDO⁄dz, where is the vertical turbulent diffusivity and () the vertical concentration of dissolved oxygen. To compute oxygen flux, a fast-response temperature and optical oxygen logger was attached to a temperature microstructure profiler and casts were obtained throughout the summer stratification period. The profiles were synchronized by aligning the temperature channels from the two instruments. To solve Fick’s Law, was obtained from the microstructure data using a buoyancy Reynolds number parameterization and ⁄ was obtained from the oxygen logger. The results show negligible oxygen flux through the thermocline (~ 3 × 10-4 gm-2d-1) during the summer stratification period, in comparison to the oxygen sinks in the hypolimnion (sediment oxygen demand and respiration).

Large lakes of the world are habitats for diverse species, including endemic taxa, and are valuable resources that provide humanity with many ecosystem services. They are also sentinels of global and local change, and recent studies in limnology and paleolimnology have demonstrated disturbing evidence of their collective degradation in terms of depletion of resources (water and food), rapid warming and loss of ice, destruction of habitats and ecosystems, loss of species, and accelerating pollution. Large lakes are particularly exposed to anthropogenic and climatic stressors. The Second Warning to Humanity provides a framework to assess the dangers now threatening the world's large lake ecosystems and to evaluate pathways of sustainable development that are more respectful of their ongoing provision of services. Here we review current and emerging threats to the large lakes of the world, including iconic examples of lake management failures and successes, from which we identify priorities and approaches for future conservation efforts. The review underscores the extent of lake resource degradation, which is a result of cumulative perturbation through time by long-term human impacts combined with other emerging stressors. Decades of degradation of large lakes have resulted in major challenges for restoration and management and a legacy of ecological and economic costs for future generations. Large lakes will require more intense conservation efforts in a warmer, increasingly populated world to achieve sustainable, high-quality waters. This Warning to Humanity is also an opportunity to highlight the value of a long-term lake observatory network to monitor and report on environmental changes in large lake ecosystems. (C) 2020 The Authors. Published by Elsevier B.V. on behalf of International Association for Great Lakes Research.

Une meilleure compréhension des systèmes aquatiques passe par une intensification des mesures sur le terrain. Dans les lacs, la surveillance de la qualité des eaux est typiquement effectuée grâce à des sondes (température, turbidité, oxygène, fluorescence, …) qu’un opérateur descend puis remonte à travers la colonne d’eau. Dans le cadre du développement de sondes autonomes, le laboratoire de physique des systèmes aquatiques (APHYS) et le laboratoire d'actionneurs intégrés (LAI) cherchent à concevoir un entraînement électrique à très basse consommation permettant de réguler la profondeur de plongée d'une sonde. Dans ce projet, il est demandé à l'étudiant d'effectuer une étude de faisabilité pour des entraînements permettant de déplacer l'une de ces sondes de la surface de l'eau au fond du lac. Une attention toute particulière doit être apportée à la consommation énergétique de cet entraînement puisque le système doit être capable d'effectuer plusieurs cycles de plongées et remontées, restant ainsi plusieurs mois sans intervention externe. La définition exacte du cahier des charges se fera en tout début de projet, en discussion avec les différentes parties. En plus de la gestion énergétique, l'encapsulation du système pour assurer son fonctionnement dans un milieu hostile tel que les profondeurs d'un lac fera l'objet d'une attention toute particulière.