Material flow analysis for Europe: An exergoecological approach

Material flow analysis is a key tool to quantify and monitor the use of natural resources. A very visual way to undertake such analyses representing the mineral trade is through Sankey diagrams, in which the mineral resources that are extracted, imported, exported, recycled and consumed within the given boundaries are represented with the arrows proportional to their respective quantities. Yet Sankey diagrams alone are not sensitive to the quality of the resources as they only reflect tonnage. This issue can lead to misleading conclusions and thereby not effective resource policies. A way to overcome this deficiency is representing the flows in exergy replacement cost (ERC) terms instead of tonnage. Exergy replacement cost is a concept derived from the second law of thermodynamics and assesses the exergy cost required to return with available technologies a given mineral to its initial conditions of composition and concentration in the mines where it was found, once it has been dispersed after use. Using this methodology, minerals are physically valued in terms of their respective scarcities and the effort (in exergy cost terms) required to produce them. Accordingly, in this paper the so-called exergoecology method is used to evaluate mineral trade and foreign mineral dependency in the EU-28 for 1995 to 2012. Using the year 2011 as a case study, it can be seen using this novel approach that 45.8% of the total input of minerals are imported resulting in lower values of self-sufficiency than if a traditional MFA were applied (0.45 for minerals and 0.41 for fossil fuels, in contrast to 0.79 and 0.52 obtained respectively when using tonnes). Analyzing 10 of the 20 minerals deemed critical by the European Commission, of the total internal production, 0.88% corresponded to critical minerals when data were expressed in tonnes and 3.19% when expressed in exergy replacement costs, highlighting their relevance respect to other minerals. This external dependency leaves Europe in a delicate situation regarding fossil fuels and non-fuel minerals supply highlighting the importance of recycling especially scarce minerals and searching for alternative sources.     

A job-shop scheduling approach for optimising sugarcane rail operations

The sugarcane transport system is very complex and uses a daily schedule, consisting of a set of locomotives runs, to satisfy the requirements of the mill and harvesters. The total cost of sugarcane transport operations is very high; over 35% of the total cost of sugarcane production in Australia is incurred in cane transport. Producing efficient schedules for sugarcane transport can reduce the cost and limit the negative effects that this system can have on the raw sugar production system. In this paper, the sugarcane rail operations are formulated as a blocking job shop scheduling problem. A mixed integer programming approach is used to formulate the shop job scheduling problem. Mixed integer programming and constraint programming search techniques are integrated for solving the problem. A case study is solved to test the approach.     

Prospects for Cellulosic Biofuel Production in the Northeastern United States: A Scenario Analysis

Secure access to energy and food are two of the challenges facing the Northeast region of the United States. Traditional biofuel feedstocks, such as corn and oil seed, are able to satisfy energy requirements. However, they compete with food production for desirable land and water resources and, in any case, are not likely to exploit the region's current comparative advantages. This study investigates a potential solution to the energy security problem in the Northeast: biofuel from advanced feedstock in the form of net forest growth and woody wastes, of which the region has abundant endowments. The federal government has committed to requiring 79.5 billion liters (BL) of advanced biofuel production annually by 2022. We evaluate both the physical capacity for its production and its cost competitiveness using an input‐output model of consumption, production, and trade in the 13‐state region. The model minimizes resource use required to satisfy given consumer demand using alternative technological options and subject to resource constraints. We compile data from the technical literature quantifying state‐level biofuel feedstock endowments and the technological requirements for cellulosic ethanol production. We find that exploiting the region's endowment of cellulosic feedstock requires either making the price of biofuels competitive with gasoline through subsidies or restricting imports of gasoline. Based on this initial investigation, we conclude that the region can produce significant amounts of advanced biofuel, up to 20.28 BL of cellulosic ethanol per year, which could displace nearly 12.5% of the gasoline that is now devoted to motorized transport in the region.     

Shifting Trade Patterns as a Means of Reducing Global Carbon Dioxide Emissions

This article extends and applies the world trade model with bilateral trade (WTMBT), a linear program with any number of goods, factors, and regional trade partners that determines regional production, bilateral trade patterns, and region-specific prices on the basis of comparative advantage by minimizing factor use. The model provides a consistent analysis of the global production system, representing geographical location at a regional level, region-specific technologies at a sector level, emissions from production, and resource constraints and costs. An illustrative analysis investigates how changes in the geographic distribution of production could contribute to reducing global carbon dioxide (CO₂) emissions and at what cost. The model provides a bridge between global objectives and their determinants and consequences in specific sectors in individual regions. Multi-objective analysis is used to construct a trade-off curve between global factor costs and CO₂ emissions. The relevance of both primal and dual solution variables is demonstrated. In particular, changes in goods prices and emissions are investigated. We conclude that the main impact of tightening carbon constraints is a substantial reduction in international trade accompanied by a shift away from regions most reliant on the combustion of coal. In addition to the analysis of the overall global trends, including the impact on prices, the implications of the global carbon constraint for one specific industry are investigated.     

Determinants of Default in P2P Lending

This paper studies P2P lending and the factors explaining loan default. This is an important issue because in P2P lending individual investors bear the credit risk, instead of financial institutions, which are experts in dealing with this risk. P2P lenders suffer a severe problem of information asymmetry, because they are at a disadvantage facing the borrower. For this reason, P2P lending sites provide potential lenders with information about borrowers and their loan purpose. They also assign a grade to each loan. The empirical study is based on loans’ data collected from Lending Club (N = 24,449) from 2008 to 2014 that are first analyzed by using univariate means tests and survival analysis. Factors explaining default are loan purpose, annual income, current housing situation, credit history and indebtedness. Secondly, a logistic regression model is developed to predict defaults. The grade assigned by the P2P lending site is the most predictive factor of default, but the accuracy of the model is improved by adding other information, especially the borrower’s debt level.     

Techno-economic analysis of a transient plant-based platform for monoclonal antibody production

Plant-based biomanufacturing of therapeutic proteins is a relatively new platform with a small number of commercial-scale facilities, but offers advantages of linear scalability, reduced upstream complexity, reduced time to market, and potentially lower capital and operating costs. In this study we present a detailed process simulation model for a large-scale new “greenfield” biomanufacturing facility that uses transient agroinfiltration of Nicotiana benthamiana plants grown hydroponically indoors under light-emitting diode lighting for the production of a monoclonal antibody. The model was used to evaluate the total capital investment, annual operating cost, and cost of goods sold as a function of mAb expression level in the plant (g mAb/kg fresh weight of the plant) and production capacity (kg mAb/year). For the Base Case design scenario (300 kg mAb/year, 1 g mAb/kg fresh weight, and 65% recovery in downstream processing), the model predicts a total capital investment of $122 million dollars and cost of goods sold of $121/g including depreciation. Compared with traditional biomanufacturing platforms that use mammalian cells grown in bioreactors, the model predicts significant reductions in capital investment and >50% reduction in cost of goods compared with published values at similar production scales. The simulation model can be modified or adapted by others to assess the profitability of alternative designs, implement different process assumptions, and help guide process development and optimization.     

Mass Production of the Beneficial Nematode Heterorhabditis bacteriophora and Its Bacterial Symbiont Photorhabdus luminescens

Entomoparasitic nematodes (EPNs) are being commercialized as a biocontrol measure for crop insect pests, as they provide advantages over common chemical insecticides. Mass production of these nematodes in liquid media has become a major challenge for commercialization. Producers are not willing to share the trade secrets of mass production and by doing so, have made culturing EPNs extremely difficult to advance existing technologies. Theoretically, mass production in liquid media is an ideal culturing method as it increases cost efficiency and nematode quantity. This paper will review current culturing methodologies and suggest basic culturing parameters for mass production. This review is focused on Heterorhabditis bacteriophora; however, this information can be useful for other nematode species.     

The mineral composition of the Robusta banana plant

Summary The problem of the nutrition of the banana plant and the limitations of traditional field fertilizer trials are described. Complementary studies of total uptake are valuable and have been carried out at various sites in the Eastern Caribbean. In this paper, dry-matter production at different stages of growth of Robusta bananas is presented. Differences in pattern are related to site factors. Distribution and redistribution of dry matter amongst the various plant organs are given for the different stages of growth. Calculations of fresh and dry matter for a field production of 25 and 50 tonnes per ha have been made. re]19720703     

Process design and economic studies of alternative fermentation methods for the production of ethanol

Cell recycle and vacuum fermentation processes are described for the continuous production of ethanol. Preliminary process design studies are employed to make an economic comparison of these alternative fermentation schemes with continuous and batch fermentation technologies. Designs are based on a production capacity of 78,000 gal 95% ethanol (EtOH)/day employing molasses as the fermentation substrate. The studies indicate that a 57% reduction in fixed capital investment is realized by continuous rather than batch operation. Further decreases in required capital investment of 68 and 71% over batch fermentation were obtained for cell recycle and vacuum operation, respectively. However, ethanol production costs were dominated by the cost of molasses, representing over 75% of the total manufacturing cost. But, when a reasonable yeast by-product credit was assumed, the net production cost for 95% ethanol was estimated at 82.3 and 80.6 cent/gal, for the cell recycle and vacuum processes, respectively.     

Dynamically optimal strategies for managing resistance to genetically modified crops

This paper develops a dynamic model of the evolution of pest a population and pest resistance to characterize the socially optimal refuge strategy for managing a pest's resistance to genetically modified crops. Previous theoretical economic analyses of this problem focus on steady states; we also address refuge policies along the optimal path to the final equilibrium. To elaborate on our theoretical analysis of the resistance problem, we develop a simulation model calibrated to cotton (Gossypium spp.) production in China. Our results show the importance of fitness cost as a determinant of the qualitative nature of optimal refuge policies.     

Superiority of spaced seeds for homology search

In homology search, good spaced seeds have higher sensitivity for the same cost (weight). However, elucidating the mechanism that confers power to spaced seeds and characterizing optimal spaced seeds still remain unsolved. This paper investigates these two important open questions by formally analyzing the average number of non-overlapping hits and the hit probability of a spaced seed in the Bernoulli sequence model. We prove that when the length of a non-uniformly spaced seed is bounded above by an exponential function of the seed weight, the seed outperforms strictly the traditional consecutive seed of the same weight in both 1) the average number of non-overlapping hits and 2) the asymptotic hit probability. This clearly answers the first problem mentioned above in the Bernoulli sequence model. The theoretical study in this paper also gives a new solution to finding long optimal seeds.     

Optimal Control of Gypsy Moth Populations

This study investigates an optimal strategy for the cost effective control of gypsy moth populations. Gypsy moth populations cycle between low sparse numbers to high outbreak levels and it is during the outbreak levels that the moths cause extensive damage to plant foliage which can lead to deforestation. Deforestation can result in significant economic damage to infested areas, and consequently, there have been many efforts to control moth populations. One effective method of control is the use of the biocontrol agent, Gypchek, but its production is costly. We develop a mathematical model which combines population dynamics and optimal control of the moth population to explore strategies by which the total cost of the gypsy moth problem (economic damage and cost of Gypchek) can be minimized.     

Small sperm,uniparental inheritance and selfish cytoplasmic elements: a comparison of two models

It has previously been suggested that small sperm size may be an adaptation to achieve uniparental inheritance of organelles, and hence to prevent the spread of selfish cytoplasmic elements. Such an explanation for anisogamy implies a mechanism whereby the male gamete eliminates its own cytoplasm prior to fusion with the egg. A model has been presented demonstrating the invasion and persistence of a modifier that acts gametically to kill its own organelles. Here we show, however, that this model is far from robust; indeed, if any cost is associated with the modifier it cannot persist. We also show that despite an empirically demonstrated association between anisogamy and multicellularity, this result also applies if the analysis is applied in the multicellular case. This class of model contrasts with the majority of analyses in which the modifier kills off the incoming gamete’s organelles. We show that these models are highly robust, even if uniparental inheritance is imperfect.     

Ecological network analysis for virtual water trade system: A case study for the Baiyangdian Basin in Northern China

Increasing inter-sectoral virtual water trade has organized the world into a huge web and different trade sectors will impact each other directly and indirectly through productions or services. It is hard to make reasonable virtual water policies before understanding the interdependency between different trade sectors in virtual water production and consumption. This paper introduces a method, named ecological network analysis, to show the independence and interaction between different trade sectors. A virtual water trade network model of the Baiyangdian Basin was built as an example of how this approach provides insights into the trade system. Control, utility, unit environ and final contribution ratio methods of network analysis were used to identify the quantitative dependency relations, distinguish the beneficiary and the contributor, detect fate of boundary input and output in any component and explore the contribution of each compartment to virtual water trade system. Results showed these methods could well depict the mutual relations in trade system and direct, observable relations may differ from integral ones. This paper revealed ways to optimize virtual water trade structure by adjusting the relationships among compartments, thereby demonstrating how ecological network analysis can be used in future basin water resources management.     

Risk Analysis Modeling of Production Costs and Occupational Health Exposure of Single‐Wall Carbon Nanotube Manufacturing

Considerable uncertainty exists about occupational risks, future environmental health and safety (EHS) standards, and associated production and compliance costs for single‐wall carbon nanotube (SWNT) manufacturing processes. We propose and illustrate the use of risk analysis Monte Carlo (MC) models to assess cost and exposure trade‐offs of the high‐pressure carbon monoxide (HiPco) SWNT manufacturing process given these uncertainties. Assumptions regarding the timing, frequency, magnitude, and expense of EHS standards are modeled as stochastic events and examined for their impact on the expected values, variances, and probability distributions of total production costs and occupational exposure. With a better understanding of associated risks, these models can help policy makers and manufacturers explore potential EHS benefits, consequences, and trade‐offs. For example, results suggest that voluntary implementation of a low level of protection (rather than none at all) can lead to reduced cost and exposure uncertainty with insignificant increases in production costs, as well as lowering total manufacturing and liability costs, depending on the assumptions made. Conversely, slower implementation rates of higher standards produce greater uncertainty in long‐term costs and exposure. More generally, the results of this study underscore three important observations: (1) Expected costs alone are insufficient for informed decision making; (2) the best level of standards, overall cost, and optimal voluntary standards are highly dependent on uncertain health effects; and (3) the resultant amount of uncertainty in total costs and exposure can be extreme.     

Drug Abuse in China: Past,Present and Future

Following British importation of opium to China in 1760s, the use and production of the drug in China increased dramatically. This situation was aggravated after the failure of Opium Wars that occurred between the United Kingdom and the Qing Empire in China with the aim of forcing China to import British Opium; this war made China open the door to a free flowing opium trade, with disastrous social and public health consequences. The subsequent rise of the new China created drug-free atmosphere by strict legislation and punishment, in which drug use greatly decreased. However, in the context of governmental reform and the open-door policies of the 1980s, drug abuse has re-emerged as a major public health problem. Today, drug abuse is highly linked to the spread of HIV/AIDS and to drug-related crimes in China. To combat the severe drug problem facing the nation, the Chinese government has adopted the Methadone Maintenance Treatment program, a multi-faceted therapeutic approach that aims to reduce the health and social problem induced by drug epidemics. In addition, traditional Chinese medicine, including herbal therapy and acupuncture, both found to be effective in the prevention of relapse and causes few side effects, making them useful for the treatment of opiate addiction. With continuous application of these therapies and managements that have been proved to be effective in harm reduction in the western countries, we believe that drug abuse and its related problems in China will be brought under control.     

Automatic registration and error detection of multiple slices using landmarks.

OBJECTIVES: When analysing the 3D structure of tissue, serial sectioning and staining of the resulting slices is sometimes the preferred option. This leads to severe registration problems. In this paper, a method for automatic registration and error detection of slices using landmark needles has been developed. A cost function takes some parameters from the current state of the problem to be solved as input and gives a quality of the current solution as output. The cost function used in this paper, is based on a model of the slices and the landmark needles. The method has been used to register slices of prostates in order to create 3D computer models. Manual registration of the same prostates has been undertaken and compared with the results from the algorithm. METHODS: Prostates from sixteen men who underwent radical prostatectomy were formalin fixed with landmark needles, sliced and the slices were computer reconstructed. The cost function takes rotation and translation for each prostate slice, as well as slope and offset for each landmark needle as input. The current quality of fit of the model, using the input parameters given, is returned. The function takes the built-in instability of the model into account. The method uses a standard algorithm to optimize the prostate slice positions. To verify the result, s standard method in statistics was used. RESULTS: The methods were evaluated for 16 prostates. When testing blindly, a physician could not determine whether the registration shown to him were created by the automated method described in this paper, or manually by an expert, except in one out of 16 cases. Visual inspection and analysis of the outlier confirmed that the input data had been deformed. The automatic detection of erroneous slices marked a few slices, including the outlier, as suspicious. CONCLUSIONS: The model based registration performs better than traditional simple slice-wise registration. In the case of prostate slice registration, other aspects, such as the physical slicing method used, may be more important to the final result than the selection of registration method to use.     

Inducible cell lysis systems in microbial production of bio-based chemicals

The release of products from microbial cells is an essential process for industrial scale production of bio-based chemicals. However, traditional methods of cell lysis, e.g., mechanical disruption, chemical solvent extraction, and immobilized enzyme degradation, account for a large share of the total production cost. Thus, an efficient cell lysis system is required to lower the cost. This review has focused on our current knowledge of two cell lysis systems, bacteriophage holin–endolysin system, and lipid enzyme hydrolysis system. These systems are controlled by conditionally inducible regulatory apparatus and applied in microbial production of fatty acids and polyhydroxyalkanoates. Moreover, toxin–antitoxin system is also suggested as alternative for its potential applications in cell lysis. Compared with traditional methods of cell disruption, the inducible cell lysis systems are more economically feasible and easier to control and show a promising perspective in industrial production of bio-based chemicals.     

Illegal wildlife trade in the Himalayan region of China

The Himalayan region of China, with its rich biodiversity, used to be important for hunting and collecting of medicinal plants. In the past decades, conservation attitudes and legislation for wildlife conservation have developed rapidly in China. Increasing numbers of species are listed in the state protection list and local protection lists. In the Himalayan region, the area of natural reserves is high accounting for 70% of total area of natural reserves in China. However, wildlife in Himalayan region is suffering from illegal hunting and trade even after China has enforced the China Wildlife Protection Law (CWPL). The illegal wildlife trade and smuggling across Sino-neighbouring country borders and illegal wildlife trade related to domestic use flourish in the region. Although domestic illegal trade has declined in the past ten years, international illegal trade and smuggling continue, and are even expanding, thereby threatening survival of many endangered species such as the Tibetan antelope (Pantholops hodgsoni), Giant panda (Ailuropoda melanoleuca) and Saker Falcon (Falco cherrug). Illegal wildlife trade in the region is attributed to four factors. First, the CWPL is still imperfect, especially concerning illegal trade and smuggling across borders. Second, CWPL is not fully enforced. Third, infrastructure in many nature reserves is undeveloped and human resources are lacking. Fourth, protection is hampered by differences in the laws of neighbouring countries, differences in penalties and in degrees of protection. Furthermore, national legislation is often not fully enforced in areas that are inhabited mainly by tribal and minority communities.     

Cost-Effective Control of Plant Disease When Epidemiological Knowledge Is Incomplete: Modelling Bahia Bark Scaling of Citrus

A spatially-explicit, stochastic model is developed for Bahia bark scaling, a threat to citrus production in north-eastern Brazil, and is used to assess epidemiological principles underlying the cost-effectiveness of disease control strategies. The model is fitted via Markov chain Monte Carlo with data augmentation to snapshots of disease spread derived from a previously-reported multi-year experiment. Goodness-of-fit tests strongly supported the fit of the model, even though the detailed etiology of the disease is unknown and was not explicitly included in the model. Key epidemiological parameters including the infection rate, incubation period and scale of dispersal are estimated from the spread data. This allows us to scale-up the experimental results to predict the effect of the level of initial inoculum on disease progression in a typically-sized citrus grove. The efficacies of two cultural control measures are assessed: altering the spacing of host plants, and roguing symptomatic trees. Reducing planting density can slow disease spread significantly if the distance between hosts is sufficiently large. However, low density groves have fewer plants per hectare. The optimum density of productive plants is therefore recovered at an intermediate host spacing. Roguing, even when detection of symptomatic plants is imperfect, can lead to very effective control. However, scouting for disease symptoms incurs a cost. We use the model to balance the cost of scouting against the number of plants lost to disease, and show how to determine a roguing schedule that optimises profit. The trade-offs underlying the two optima we identify—the optimal host spacing and the optimal roguing schedule—are applicable to many pathosystems. Our work demonstrates how a carefully parameterised mathematical model can be used to find these optima. It also illustrates how mathematical models can be used in even this most challenging of situations in which the underlying epidemiology is ill-understood.