356 research outputs found
Numerically efficient modeling of CNT transistors with ballistic and non-ballistic effects for circuit simulation
No full textThis paper presents an efficient carbon nanotube (CNT) transistor modeling technique which is based on cubic spline approximation of the non-equilibrium mobile charge density. The approximation facilitates the solution of the selfconsistent voltage equation in a carbon nanotube so that calculation of the CNT drain-source current is accelerated by at least two orders of magnitude. A salient feature of the proposed technique is its ability to incorporate both ballistic and nonballistic transport effects without a significant computational cost. The proposed models have been extensively validated against reported CNT ballistic and non-ballistic transport theories and experimental results
Advancements in water footprints research for achieving sustainable development goals: an overview
No full textThe water footprint (WF) is a comprehensive metric that measures the total amount of water consumption involved in the production of goods and services. It encompasses both direct and indirect water use, including blue water from fresh surface and groundwater, green water from rainfall, and gray water associated with wastewater and runoff. By providing insights into the impact of their activities on freshwater resources, the WF helps businesses, policymakers, and consumers understand and manage water use more effectively. The WF can be calculated for products, consumers, businesses, and geographic regions, providing a detailed view of water usage across the entire supply chain. Understanding the WF is crucial for promoting sustainable development and responsible resource management. It raises awareness of consumption patterns and encourages the adoption of more sustainable practices. For businesses, the WF can identify opportunities for water conservation and efficiency, leading to cost savings and improved reputation. Governments can leverage WF data to develop policies that support sustainable water management and ecosystem protection. Additionally, consumers can use WF information to make informed choices, fostering a shift toward more sustainable consumption patterns. The WF has grown into an established idea for investigating water use and its local consequences in agricultural and industrial output. Leveraging on recent advances, the WF concept is poised to be a useful tool for achieving all 17 sustainable development goals (SDGs). This chapter intends to illustrate the WF concept’s potential to guide decision-making in both the public and business domains, ultimately leading to better water management and the achievement of the SDGs
Management Impacts on Carbon Dynamics in a Sierra Nevada Mixed Conifer Forest.
No full textForest ecosystems can act as sinks of carbon and thus mitigate anthropogenic carbon emissions. When forests are actively managed, treatments can alter forests carbon dynamics, reducing their sink strength and switching them from sinks to sources of carbon. These effects are generally characterized by fast temporal dynamics. Hence this study monitored for over a decade the impacts of management practices commonly used to reduce fire hazards on the carbon dynamics of mixed-conifer forests in the Sierra Nevada, California, USA. Soil CO2 efflux, carbon pools (i.e. soil carbon, litter, fine roots, tree biomass), and radial tree growth were compared among un-manipulated controls, prescribed fire, thinning, thinning followed by fire, and two clear-cut harvested sites. Soil CO2 efflux was reduced by both fire and harvesting (ca. 15%). Soil carbon content (upper 15 cm) was not significantly changed by harvest or fire treatments. Fine root biomass was reduced by clear-cut harvest (60-70%) but not by fire, and the litter layer was reduced 80% by clear-cut harvest and 40% by fire. Thinning effects on tree growth and biomass were concentrated in the first year after treatments, whereas fire effects persisted over the seven-year post-treatment period. Over this period, tree radial growth was increased (25%) by thinning and reduced (12%) by fire. After seven years, tree biomass returned to pre-treatment levels in both fire and thinning treatments; however, biomass and productivity decreased 30%-40% compared to controls when thinning was combined with fire. The clear-cut treatment had the strongest impact, reducing ecosystem carbon stocks and delaying the capacity for carbon uptake. We conclude that post-treatment carbon dynamics and ecosystem recovery time varied with intensity and type of treatments. Consequently, management practices can be selected to minimize ecosystem carbon losses while increasing future carbon uptake, resilience to high severity fire, and climate related stresses
Decomposition of recalcitrant carbon under experimental warming in boreal forest.
No full textOver the long term, soil carbon (C) storage is partly determined by decomposition rate of carbon that is slow to decompose (i.e., recalcitrant C). According to thermodynamic theory, decomposition rates of recalcitrant C might differ from those of non-recalcitrant C in their sensitivities to global warming. We decomposed leaf litter in a warming experiment in Alaskan boreal forest, and measured mass loss of recalcitrant C (lignin) vs. non-recalcitrant C (cellulose, hemicellulose, and sugars) throughout 16 months. We found that these C fractions responded differently to warming. Specifically, after one year of decomposition, the ratio of recalcitrant C to non-recalcitrant C remaining in litter declined in the warmed plots compared to control. Consistent with this pattern, potential activities of enzymes targeting recalcitrant C increased with warming, relative to those targeting non-recalcitrant C. Even so, mass loss of individual C fractions showed that non-recalcitrant C is preferentially decomposed under control conditions whereas recalcitrant C losses remain unchanged between control and warmed plots. Moreover, overall mass loss was greater under control conditions. Our results imply that direct warming effects, as well as indirect warming effects (e.g. drying), may serve to maintain decomposition rates of recalcitrant C compared to non-recalcitrant C despite negative effects on overall decomposition
From dangerous branches to urban banyan: Facilitating aerial root growth of Ficus rubiginosa
No full textLarge urban trees have many benefits. However, falling branches pose a serious hazard to both people and infrastructure. In several tree species, aerial roots grow down from branches to the ground. These roots are capable of thickening to support the branches, lessening the risk of tree failure. Unfortunately, in urban environments most aerial roots die before reaching the ground. Here, we report a new method for encouraging aerial roots to reach the ground, developed by the second-year botany class at UNSW Sydney. Our class tested three experimental treatments on aerial roots of Ficus rubiginosa Desf. ex Vent. (Port Jackson Fig)-PVC pipes filled with sphagnum moss, PVC pipes filled with potting mix, and PVC pipes filled with sphagnum moss and topped with funnels to catch extra rainwater. All three treatments significantly improved aerial root growth, with 26 of the 30 (87%) treatment roots reaching the ground after one year compared to 0 of the 10 control roots. Our method was successful for roots up to 3 m above the ground, suggesting the potential growth rate of aerial roots is substantial when conditions are favourable. Our novel approach is an attractive and cost-effective alternative to slings and other artificial supports. This project is an example of using undergraduate practical classes to teach science while simultaneously addressing important real-world problems
Multiple ecosystem services in a working landscape.
No full textPolicy makers and practitioners are in need of useful tools and models for assessing ecosystem service outcomes and the potential risks and opportunities of ecosystem management options. We utilize a state-and-transition model framework integrating dynamic soil and vegetation properties to examine multiple ecosystem services-specifically agricultural production, biodiversity and habitat, and soil health-across human created vegetation states in a managed oak woodland landscape in a Mediterranean climate. We found clear tradeoffs and synergies in management outcomes. Grassland states maximized agricultural productivity at a loss of soil health, biodiversity, and other ecosystem services. Synergies existed among multiple ecosystem services in savanna and woodland states with significantly larger nutrient pools, more diversity and native plant richness, and less invasive species. This integrative approach can be adapted to a diversity of working landscapes to provide useful information for science-based ecosystem service valuations, conservation decision making, and management effectiveness assessments
Seasonal variation characteristics of tidal sedimentation of the middle tidal flat — A case study of tidal flat in Dafeng, Jiangsu Province, China
No full text157-162Annual field observations and sample collection
of each spring-neap tidal cycle sediments had been done on middle
tidal flat of Dafeng coast, Jiangsu
province. Grain-size and pollen analysis had been examined. Variation trends of
sedimentary particle size are basically same on different landforms on middle
tidal flat, but particle size has obvious seasonal difference. Upper of the
middle tidal flat is relative higher, the sedimentary particles are smaller. As
there is no vegetation cover in the middle tidal flat, the seasonal variation
of sporopollen characteristics has significant differences with high tidal flat
in the aspects of pollen species, number of individuals or the ratio of
Artemisia/Chenopodiaceae
Stimulation of ammonia oxidizer and denitrifier abundances by nitrogen loading: Poor predictability for increased soil N2O emission
No full textYong Zhang, Feng Zhang, Diego Abalos, Yiqi Luo, Dafeng Hui, Bruce A Hungate, Pablo García-Palacios, Yakov Kuzyakov, Jørgen Eivind Olesen, Uffe Jørgensen, Ji Chen. Stimulation of ammonia oxidizer and denitrifier abundances by nitrogen loading: Poor predictability for increased soil N2O emission.Global Change Biology.</a
Democratization and Financial Reform in Taiwan: The Political Economy of Bad-Loan Creation
No full textThis study shows that many bad loans now burdening Taiwan's financial institutions are interrelated with the society's democratization which started in the late 1980s. Democratization made the local factions and business groups more independent from the Kuomintang government. They acquired more political influence than under the authoritarian regime. These changes induced them to manage their owned financial institutions more arbitrarily and to intervene more frequently in the state-affiliated financial institutions. Moreover they interfered in financial reform and compelled the government to allow many more new banks than it had originally planned. As a result the financial system became more competitive and the qualities of loans deteriorated. Some local factions and business groups exacerbated the situation by establishing banks in order to funnel funds to themselves, sometimes illegally. Thus many bad loans were created as the side effect of democratization.Taiwan, Politics, Economy, Democratization, Finance
The etiology of esophageal cancer in high- and low- risk areas of Jiangsu province, China
No full text [Background]Esophageal cancer (EC) remains one of the most common and fatal malignancies worldwide. The geographic variation in EC occurrence is striking, and China is an area with one of the highest incidences of EC. A number of epidemiological studies have been conducted toward EC in the past decades, results suggested that tobacco smoking, alcohol drinking, unhealthy dietary factors and chronic injuries of the esophageal mucosa are important in the development of this disease. Genetic polymorphisms in enzymes involved in metabolism of carcinogens may also influence individual susceptibility. However, the effects of major lifestyle and hereditary risk factors on the development of EC remain poorly understood in China. Moreover, little attention has been paid to the etiological heterogeneity between similar areas with great risk gradient. [Methods]From 2003 to 2007, a large population-based case-control study of EC has been conducted in a selected high-risk area and a selected low-risk area of Jiangsu Province, one of the highest cancer incidence areas in China. In total, 1,520 cases and 3,879 controls were recruited. In this thesis, we evaluated the role of major lifestyle factors such as tobacco smoking, alcohol drinking and dietary factors, as well as inherited determinants including family history of cancer and genetic polymorphisms of alcohol-metabolizing related genes on the risk of EC. In addition, we investigated how much of the risk gradient between two areas could be explained by variation in the distributions of major risk factors. [Results] Tobacco smoking and alcohol drinking moderately increased the risk of EC, while the positive associations were only found among men but not among women. Dietary factors were observed to play important roles in the development of EC. Specific dietary habits i.e., fast eating speed, and hot eating and/or drinking substantially elevated EC risk and could explain more than 20% of EC cases each. High intake of salty foods and fried foods, low consumption of raw garlic were also observed to increase the risk of EC. In addition to environmental and lifestyle factors, we confirmed that a positive family history can significantly increase EC risk, and found the inheritance may modify the effect of some unhealthy lifestyles. Moreover, we further explored the relationship between EC and single nucleotide polymorphismsof ADH1B, ADH1C and ALDH2 genes. Results showed that the slow metabolizing ADH1B G allele, ADH1C G allele and ALDH2 A allele significantly increased EC risk among moderate-to-heavy alcohol drinkers, and a significant interaction was observed between ALDH2 gene and alcohol consumption. Lastly, we found that more than 60% of EC cases could be attributable to major lifestyle risk factors in the study population; furthermore, dissimilar distribution of several lifestyle factors, together with variations of hereditary factors may be largely responsible for the incidence difference between two study areas. [Conclusion]The findings in this thesis confirm that unhealthy lifestyles including smoking, alcohol drinking and some dietary factors are the predominant risk factors of EC in China, and a large proportion of incidence difference between regions at varying risk could be attributed to the different prevalence of lifestyle factors. As most of the identified risk factors are modifiable, these could be translated into risk reduction prevention programs in China, and a substantial proportion of new EC cases are expected to be prevented by eliminating or avoiding these risk factors in the population. </p
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