Causes and consequences of tipping points in river delta social-ecological systems

The sustainability of social-ecological systems within river deltas globally is in question as rapid development and environmental change trigger "negative” or “positive” tipping points depending on actors’ perspectives, e.g., regime shift from abundant sediment deposition to sediment shortage, agricultural sustainability to agricultural collapse or shift from rural to urban land. Using a systematic review of the literature, we show how cascading effects across anthropogenic, ecological, and geophysical processes have triggered numerous tipping points in the governance, hydrological and land use management of the world’s river deltas. Crossing tipping points had both positive and negative effects that generally enhanced economic development to the detriment of the environment. Assessment of deltas that featured prominently in the review revealed how outcomes of tipping points can inform the long-term trajectory of deltas towards sustainability or collapse. Management of key drivers at the delta scale can trigger positive tipping points to place social-ecological systems on a pathway towards sustainable development

Application of the Western-based adjuvant online model to Korean colon cancer patients; a single institution experience

<p>Abstract</p> <p>Background</p> <p>Adjuvant Online (AOL) is web-accessible risk-assessment model that predicts the mortality and the benefits of adjuvant therapy (<url>http://www.newadjuvantonline.com</url>). AOL has never been validated for Asian colon cancer patients.</p> <p>Methods</p> <p>Using the Yonsei Tumor Registry database, patients who were treated within the Yonsei University Health System between 1990 and 2005 for T1-4, N0-2, and M0 colon cancer were included in the calculations for survival. Observed and predicted 5-year overall survival was compared for each patient.</p> <p>Results</p> <p>The median age of the study population of 1431 patients was 60 years (range, 15–87 years), and the median follow-up duration was 7.9 years (range, 0.06–19.8 years). The predicted 5-year overall survival rate (77.7%) and observed survival (79.5%) was not statistically different (95% Confidential interval, 76.3–81.5) in all patients. Predicted outcomes were within 95% confidential interval of observed survival in both stage II and III disease, including most demographic and pathologic subgroups. Moreover, AOL more accurately predicted OS for patients with stage II than stage III.</p> <p>Conclusions</p> <p>AOL tended to offer reliable prediction for 5-year overall survival and could be used as a decision making tool for adjuvant treatment in Korean colon cancer patients whose prognosis is similar to other Asian patients.</p

Phragmites australis: How do genotypes of different phylogeographic origins differ from their invasive genotypes in growth, nitrogen allocation and gas exchange?

It has been suggested that in plant invasions, species may develop intrinsically higher gas exchange and growth rates, and greater nitrogen uptake and allocation to shoots, in their invasive range than in their native habitat under excess nutrients. In this study, native populations of two old world Phragmitesaustralis phylogeographic groups (EU and MED) were compared with their invasive populations in North America [NAint (M) and NAint (Delta)] under unlimited nutrient availability and identical environmental conditions in a common garden. We expected that both introduced groups would have higher growth, nitrogen uptake and allocation, and gas exchange rates than their native groups, but that these enhanced traits would have evolved in different ways in the two introduced ranges, because of different evolutionary histories. Biomass, leaf area, leaf nitrogen concentrations (NH4+ and NO3−) and transpiration rates increased in introduced versus native groups, whereas differences in SLA, leaf pigment concentrations and assimilation rates were due to phylogeographic origins. Despite intrinsic differences in the allocation of C and N in leaves, shoots and rhizome due to phylogeographic origin, the introduced groups invested more biomass in above-ground tissues than roots and rhizomes. Our results support the concept that invasive populations develop enhanced morphological, physiological and biomass traits in their new ranges that may assist their competiveness under nutrient-enriched conditions, however the ecophysiological processes leading to these changes can be different and depend on the evolutionary history of the genotypes