Change in future climate due to Antarctic meltwater.

Meltwater from the Antarctic Ice Sheet is projected to cause up to one metre of sea-level rise by 2100 under the highest greenhouse gas concentration trajectory (RCP8.5) considered by the Intergovernmental Panel on Climate Change (IPCC). However, the effects of meltwater from the ice sheets and ice shelves of Antarctica are not included in the widely used CMIP5 climate models, which introduces bias into IPCC climate projections. Here we assess a large ensemble simulation of the CMIP5 model 'GFDL ESM2M' that accounts for RCP8.5-projected Antarctic Ice Sheet meltwater. We find that, relative to the standard RCP8.5 scenario, accounting for meltwater delays the exceedance of the maximum global-mean atmospheric warming targets of 1.5 and 2 degrees Celsius by more than a decade, enhances drying of the Southern Hemisphere and reduces drying of the Northern Hemisphere, increases the formation of Antarctic sea ice (consistent with recent observations of increasing Antarctic sea-ice area) and warms the subsurface ocean around the Antarctic coast. Moreover, the meltwater-induced subsurface ocean warming could lead to further ice-sheet and ice-shelf melting through a positive feedback mechanism, highlighting the importance of including meltwater effects in simulations of future climate.

Parental energy-sensing pathways control intergenerational offspring sex determination in the nematode Auanema freiburgensis.

BACKGROUND: Environmental stimuli experienced by the parental generation influence the phenotype of subsequent generations (Demoinet et al., Proc Natl Acad Sci U S A 114:E2689-E2698, 2017; Burton et al., Nat Cell Biol 19:252-257, 2017; Agrawal et al., Nature 401:60-63, 1999). The effects of these stimuli on the parental generation may be passed through the germline, but the mechanisms at the basis of this non-Mendelian type of inheritance, their level of conservation, how they lead to adaptive vs non-adaptive, and intergenerational vs transgenerational inheritance are poorly understood. Here we show that modulation of nutrient-sensing pathways in the parental generation of the nematode Auanema freiburgensis regulates phenotypic plasticity of its offspring. RESULTS: In response to con-specific pheromones indicative of stress, AMP-activated protein kinase (AMPK), mechanistic target of rapamycin complex 1 (mTORC1), and insulin signaling regulate stress resistance and sex determination across one generation, and these effects can be mimicked by pathway modulators. The effectors of these pathways are closely associated with the chromatin, and their regulation affects the chromatin acetylation status in the germline. CONCLUSION: These results suggest that highly conserved metabolic sensors regulate phenotypic plasticity through regulation of subcellular localization of their effectors, leading to changes in chromatin acetylation and epigenetic status of the germline.

Wind-Driven Formation of Ice Bridges in Straits.

Ice bridges are static structures composed of tightly packed sea ice that can form during the course of its flow through a narrow strait. Despite their important role in local ecology and climate, the formation and breakup of ice bridges is not well understood and has proved difficult to predict. Using long-wave approximations and a continuum description of sea ice dynamics, we develop a one-dimensional theory for the wind-driven formation of ice bridges in narrow straits, which is verified against direct numerical simulations. We show that for a given wind stress and minimum and maximum channel widths, a steady-state ice bridge can only form beyond a critical value of the thickness and the compactness of the ice field. The theory also makes quantitative predictions for ice fluxes, which are particularly useful to estimate the ice export associated with the breakup of ice bridges. We note that similar ideas are applicable to dense granular flows in confined geometries.

Selective laparoscopic approach in suspected gallbladder malignancy.

BACKGROUND AND OBJECTIVES: We examined patients with clinical findings that are concerning for gallbladder malignancy to determine the incidence of pathology-confirmed malignancy and to discover factors that may be used to determine which patients may be initially treated with a laparoscopic approach. METHODS: All patients referred to a surgical oncologist with preoperative findings that are concerning for gallbladder malignancy who had not undergone previous surgical resection from 2005 to 2011 were reviewed. Variables collected included demographics, imaging, operative findings, and final pathology. Patients were grouped into 3 categories based on preoperative findings: gallbladder mass, irregular wall thickening, and abnormal intraoperative findings on previous diagnostic laparoscopy. RESULTS: Twenty-nine of 4474 patients evaluated for gallbladder pathology during the study period met the inclusion criteria. Preoperative imaging included computed tomography, ultrasonography, and magnetic resonance imaging. Twelve patients had multiple imaging studies. Eight patients were initially treated with a laparoscopic approach with 3 conversions to an open procedure. Forty-eight percent of patients had pathology-confirmed malignancy. Patients without a discrete mass on imaging were more likely to have benign disease (P = .04). CONCLUSIONS: Our results demonstrate that >50% of patients with suspicious preoperative findings had benign pathology, suggesting that the initial laparoscopic approach in selected patients may be appropriate.