Displacement and degradation: Impediments to agricultural livelihoods among ethnic minority farmers in post-war Sri Lanka.

Our understandings of the effects of war on land and resource access following armed conflicts are often shaped (and limited) by a reliance upon remotely sensed data. Here, we analyze household-level survey and community-level focus group data collected in Sri Lanka following the end of the nation's ethno-religiously rooted civil war (1983-2009) to determine if and how the war differently affected the nation's rice farmers. Our synthetic analyses revealed geographic variation in agricultural livelihood viability in post-war Sri Lanka, demonstrating how the protracted effects of war are exacerbating the vulnerability of rural Sri Lanka's ethno-religious minority (Tamil and Moor) populations by (re-)shaping access to critical natural resources, including both land and irrigation water.

Resource users as land-sea links in coastal and marine socioecological systems.

Coastal zones, which connect terrestrial and aquatic ecosystems, are among the most resource-rich regions globally and home to nearly 40% of the global human population. Because human land-based activities can alter natural processes in ways that affect adjacent aquatic ecosystems, land-sea interactions are increasingly recognized as critical to coastal conservation planning and governance. However, the complex socioeconomic dynamics inherent in coastal and marine socioecological systems (SESs) have received little consideration. Drawing on knowledge generalized from long-term studies in Caribbean Nicaragua, we devised a conceptual framework that clarifies the multiple ways socioeconomically driven behavior can link the land and sea. In addition to other ecosystem effects, the framework illustrates how feedbacks resulting from changes to aquatic resources can influence terrestrial resource management decisions and land uses. We assessed the framework by applying it to empirical studies from a variety of coastal SESs. The results suggest its broad applicability and highlighted the paucity of research that explicitly investigates the effects of human behavior on coastal SES dynamics. We encourage researchers and policy makers to consider direct, indirect, and bidirectional cross-ecosystem links that move beyond traditionally recognized land-to-sea processes.

Los Usuarios de Recursos como Conexiones entre la Tierra y el Mar dentro de los Sistemas Socioecológicos Marinos y Costeros Resumen Las zonas costeras, que conectan los ecosistemas terrestres y acuáticos, se encuentran entre las regiones más ricas en recursos a nivel mundial y además albergan a casi el 40% de la población humana de todo el mundo. Ya que las actividades humanas terrestres pueden alterar los procesos naturales de manera que terminan por afectar a los ecosistemas acuáticos adyacentes, cada vez se reconoce más a las interacciones tierra-mar como críticas para la planeación de la conservación y la gestión costera. Sin embargo, las complejas dinámicas socioeconómicas inherentes a los sistemas socioecológicos (SES) marinos y costeros han recibido poca atención. Con el conocimiento generalizado a partir de los estudios a largo plazo realizados en el Caribe de Nicaragua como punto de partida, diseñamos un marco conceptual que clarifica las múltiples formas en las que el comportamiento con origen socioeconómico puede conectar a la tierra y al mar. Sumado a otros efectos de los ecosistemas, el marco conceptual ilustró cómo los comentarios resultantes de los cambios ocurridos en los recursos acuáticos pueden influir sobre las decisiones de manejo de recursos terrestres y de uso de suelo. Evaluamos el marco conceptual mediante su aplicación a los estudios empíricos de una variedad de SES costeros. Los resultados sugirieron su aplicabilidad generalizada y resaltaron la escasez de investigaciones busquen específicamente los efectos del comportamiento humano sobre las dinámicas de los SES costeros. Alentamos a los investigadores y a los formuladores de políticas a considerar las conexiones directas, indirectas y bidireccionales entre ecosistemas que van más allá de los procesos de tierra a mar reconocidos tradicionalmente.

Correction: Eco-Label Conveys Reliable Information on Fish Stock Health to Seafood Consumers.

[This corrects the article DOI: 10.1371/journal.pone.0043765.].

Origin of Broad Emission Spectra in InP Quantum Dots: Contributions from Structural and Electronic Disorder.

The ensemble emission spectra of colloidal InP quantum dots are broader than achievable spectra of cadmium- and lead-based quantum dots, despite similar single-particle line widths and significant efforts invested in the improvement of synthetic protocols. We seek to explain the origin of persistently broad ensemble emission spectra of colloidal InP quantum dots by investigating the nature of the electronic states responsible for luminescence. We identify a correlation between red-shifted emission spectra and anomalous broadening of the excitation spectra of luminescent InP colloids, suggesting a trap-associated emission pathway in highly emissive core-shell quantum dots. Time-resolved pump-probe experiments find that electrons are largely untrapped on photoluminescence relevant time scales pointing to emission from recombination of localized holes with free electrons. Two-dimensional electronic spectroscopy on InP quantum dots reveals multiple emissive states and increased electron-phonon coupling associated with hole localization. These localized hole states near the valence band edge are hypothesized to arise from incomplete surface passivation and structural disorder associated with lattice defects. We confirm the presence and effect of lattice disorder by X-ray absorption spectroscopy and Raman scattering measurements. Participation of localized electronic states that are associated with various classes of lattice defects gives rise to phonon-coupled defect related emission. These findings explain the origins of the persistently broad emission spectra of colloidal InP quantum dots and suggest future strategies to narrow ensemble emission lines comparable to what is observed for cadmium-based materials.

Coastal livelihood transitions under globalization with implications for trans-ecosystem interactions.

Anthropogenic threats to natural systems can be exacerbated due to connectivity between marine, freshwater, and terrestrial ecosystems, complicating the already daunting task of governance across the land-sea interface. Globalization, including new access to markets, can change social-ecological, land-sea linkages via livelihood responses and adaptations by local people. As a first step in understanding these trans-ecosystem effects, we examined exit and entry decisions of artisanal fishers and smallholder farmers on the rapidly globalizing Caribbean coast of Nicaragua. We found that exit and entry decisions demonstrated clear temporal and spatial patterns and that these decisions differed by livelihood. In addition to household characteristics, livelihood exit and entry decisions were strongly affected by new access to regional and global markets. The natural resource implications of these livelihood decisions are potentially profound as they provide novel linkages and spatially-explicit feedbacks between terrestrial and marine ecosystems. Our findings support the need for more scientific inquiry in understanding trans-ecosystem tradeoffs due to linked-livelihood transitions as well as the need for a trans-ecosystem approach to natural resource management and development policy in rapidly changing coastal regions.

Controlling quantum-beating signals in 2D electronic spectra by packing synthetic heterodimers on single-walled carbon nanotubes.

In multidimensional spectroscopy, dynamics of coherences between excited states report on the interactions between electronic states and their environment. The prolonged coherence lifetimes revealed through beating signals in the spectra of some systems may result from vibronic coupling between nearly degenerate excited states, and recent observations confirm the existence of such coupling in both model systems and photosynthetic complexes. Understanding the origin of beating signals in the spectra of photosynthetic complexes has been given considerable attention; however, strategies to generate them in artificial systems that would allow us to test the hypotheses in detail are still lacking. Here we demonstrate control over the presence of quantum-beating signals by packing structurally flexible synthetic heterodimers on single-walled carbon nanotubes, and thereby restrict the motions of chromophores. Using two-dimensional electronic spectroscopy, we find that both limiting the relative rotation of chromophores and tuning the energy difference between the two electronic transitions in the dimer to match a vibrational mode of the lower-energy monomer are necessary to enhance the observed quantum-beating signals.

Scalable Ligand-Mediated Transport Synthesis of Organic-Inorganic Hybrid Perovskite Nanocrystals with Resolved Electronic Structure and Ultrafast Dynamics.

Colloidal perovskite nanocrystals support bright, narrow PL tunable over the visible spectrum. However, bandgap tuning of these materials remains limited to laboratory-scale syntheses. In this work, we present a polar-solvent-free ligand-mediated transport synthesis of high-quality organic-inorganic perovskite nanocrystals under ambient conditions with photoluminescence quantum yields up to 97%. Our synthesis employs a ligand-mediated transport mechanism that circumvents the need for exquisite external control (e.g., temperature control, inert-gas protection, dropwise addition of reagents) required by other methods due to extremely fast reaction kinetics. In the ligand-mediated transport mechanism, multiple equilibria cooperatively dictate reaction rates and enable precise control over NC size. These small nanocrystals exhibit high photoluminescence quantum yields due to quantum confinement. Nanosecond transient absorption spectroscopy experiments reveal a fluence-independent PL decay originating from exciton recombination. Two-dimensional electronic spectroscopy resolves multiple spectral features reflecting the electronic structure of the nanocrystals. The resolved features exhibit size-dependent spectral positions, further indicating the synthesized nanocrystals are quantum-confined.

Examining adaptations to water stress among farming households in Sri Lanka's dry zone.

Climate change is increasing water scarcity in Sri Lanka. Whether these changes will undermine national-level food security depends upon the ability of the small-scale farmers that dominate rice production and the institutions that support them to overcome the challenges presented by changing water availability. Analyzing household survey data, this research identifies household, institutional, and agroecological factors that influence how water-stressed farmers are working to adapt to changing conditions and how the strategies they employ impact rice yields. Paralleling studies conducted elsewhere, we identified institutional factors as particularly relevant in farmer adaptation decisions. Notably, our research identified farmers' use of hybrid seed varietals as the only local climate adaptation strategy to positively correlate with farmers' rice yields. These findings provide insight into additional factors pertinent to successful agricultural adaptation and offer encouraging evidence for policies that promote plant breeding and distribution in Sri Lanka as a means to buffer the food system to climate change-exacerbated drought.

Agroforestry Practices Promote Biodiversity and Natural Resource Diversity in Atlantic Nicaragua.

Tropical forest conversion to pasture, which drives greenhouse gas emissions, soil degradation, and biodiversity loss, remains a pressing socio-ecological challenge. This problem has spurred increased interest in the potential of small-scale agroforestry systems to couple sustainable agriculture with biodiversity conservation, particularly in rapidly developing areas of the tropics. In addition to providing natural resources (i.e. food, medicine, lumber), agroforestry systems have the potential to maintain higher levels of biodiversity and greater biomass than lower diversity crop or pasture systems. Greater plant diversity may also enhance soil quality, further supporting agricultural productivity in nutrient-limited tropical systems. Yet, the nature of these relationships remains equivocal. To better understand how different land use strategies impact ecosystem services, we characterized the relationships between plant diversity (including species richness, phylogenetic diversity, and natural resource diversity), and soil quality within pasture, agroforests, and secondary forests, three common land use types maintained by small-scale farmers in the Pearl Lagoon Basin, Nicaragua. The area is undergoing accelerated globalization following the 2007 completion of the region's first major road; a change which is expected to increase forest conversion for agriculture. However, farmer agrobiodiversity maintenance in the Basin was previously found to be positively correlated with affiliation to local agricultural NGOs through the maintenance of agroforestry systems, despite these farmers residing in the communities closest to the new road, highlighting the potential for maintaining diverse agroforestry agricultural strategies despite heightened globalization pressures. We found that agroforestry sites tended to have higher surface soil %C, %N, and pH relative to neighboring to secondary forest, while maintaining comparable plant diversity. In contrast, pasture reduced species richness, phylogenetic diversity, and natural resource diversity. No significant relationships were found between plant diversity and the soil properties assessed; however higher species richness and phylodiversity was positively correlated with natural resource diversity. These finding suggest that small, diversified agroforestry systems may be a viable strategy for promoting both social and ecological functions in eastern Nicaragua and other rapidly developing areas of the tropics.

Disease spectrum and use of cholecystolithotomy in gallstone ileus transection.

BACKGROUND: Gallstone ileus is a heterogeneous and highly morbid condition that suffers from a lack of consensus regarding the timing and approach to management of the biliary tree and associated fistula. METHODS: We report three cases that demonstrate the spectrum of gallstone ileus with classical examples of both Barnard's and Bouveret's syndromes. Clinical presentation, diagnostic imaging, surgical technique and outcome are discussed. RESULTS: One patient with Barnard's syndrome presented with recurrent gallstone ileus. To minimize the risks of complex, definitive biliary surgery and avoid further recurrent episodes, a cholecystolithotomy was performed with effect. Two cases of Bouveret's syndrome were successfully managed with enterolithotomy/cholecystectomy and multivisceral resection respectively, thus highlighting the diverse nature of this disease and management options. CONCLUSIONS: Following enterolithotomy, potentially morbid, definitive one-stage surgery in typically compromised, elderly patients needs to be weighed against the risk of recurrence and ongoing biliary pathology. We suggest the use of open cholecystolithotomy for the removal of residual gallstones when the patient is not suitable for definitive biliary surgery.

Eco-label conveys reliable information on fish stock health to seafood consumers.

Concerns over fishing impacts on marine populations and ecosystems have intensified the need to improve ocean management. One increasingly popular market-based instrument for ecological stewardship is the use of certification and eco-labeling programs to highlight sustainable fisheries with low environmental impacts. The Marine Stewardship Council (MSC) is the most prominent of these programs. Despite widespread discussions about the rigor of the MSC standards, no comprehensive analysis of the performance of MSC-certified fish stocks has yet been conducted. We compared status and abundance trends of 45 certified stocks with those of 179 uncertified stocks, finding that 74% of certified fisheries were above biomass levels that would produce maximum sustainable yield, compared with only 44% of uncertified fisheries. On average, the biomass of certified stocks increased by 46% over the past 10 years, whereas uncertified fisheries increased by just 9%. As part of the MSC process, fisheries initially go through a confidential pre-assessment process. When certified fisheries are compared with those that decline to pursue full certification after pre-assessment, certified stocks had much lower mean exploitation rates (67% of the rate producing maximum sustainable yield vs. 92% for those declining to pursue certification), allowing for more sustainable harvesting and in many cases biomass rebuilding. From a consumer's point of view this means that MSC-certified seafood is 3-5 times less likely to be subject to harmful fishing than uncertified seafood. Thus, MSC-certification accurately identifies healthy fish stocks and conveys reliable information on stock status to seafood consumers.

Many faces of pancreaticobiliary reflux.

Pancreaticobiliary reflux may occur either as a result of an anatomically abnormal pancreaticobiliary junction or because of a functionally impaired sphincter despite a normal radiological appearance. It is associated with a wide spectrum of biliary diseases, including gall bladder and bile duct carcinoma. Pancreaticobiliary maljunction and related biliary reflux have been studied extensively in Southeast Asian populations and associations with choledochal cyst and biliary malignancy defined. However, reflux in the absence of ductal malunion has only been described relatively recently and its significance with respect to biliary malignancy requires clarification. We present four cases of pancreaticobiliary reflux to demonstrate the varied associations of this under-recognized disorder and review the related management issues.