Tyson Foods, Inc. v. Bouaphakeo: The Use of Statistical Evidence in Class Actions

Statistical analysis potentially plays an important role in class-action litigation, but the use of such evidence is limited at the class-certification stage of such suits. This Commentary previews an upcoming Supreme Court case that deals with the question of whether inferential evidence may be used to certify a class in a class-action lawsuit. Because this case deals with a violation of a duty, imposed by statute, on the defendant, this Commentary argues that under existing precedent, inferential statistical evidence is appropriate for determining the question of class-certification

Incident Light Frequency-based Image Defogging Algorithm

Considering the problem of color distortion caused by the defogging algorithm based on dark channel prior, an improved algorithm was proposed to calculate the transmittance of all channels respectively. First, incident light frequency's effect on the transmittance of various color channels was analyzed according to the Beer-Lambert's Law, from which a proportion among various channel transmittances was derived; afterwards, images were preprocessed by down-sampling to refine transmittance, and then the original size was restored to enhance the operational efficiency of the algorithm; finally, the transmittance of all color channels was acquired in accordance with the proportion, and then the corresponding transmittance was used for image restoration in each channel. The experimental results show that compared with the existing algorithm, this improved image defogging algorithm could make image colors more natural, solve the problem of slightly higher color saturation caused by the existing algorithm, and shorten the operation time by four to nine times

On Reject and Refine Options in Multicategory Classification

In many real applications of statistical learning, a decision made from misclassification can be too costly to afford; in this case, a reject option, which defers the decision until further investigation is conducted, is often preferred. In recent years, there has been much development for binary classification with a reject option. Yet, little progress has been made for the multicategory case. In this article, we propose margin-based multicategory classification methods with a reject option. In addition, and more importantly, we introduce a new and unique refine option for the multicategory problem, where the class of an observation is predicted to be from a set of class labels, whose cardinality is not necessarily one. The main advantage of both options lies in their capacity of identifying error-prone observations. Moreover, the refine option can provide more constructive information for classification by effectively ruling out implausible classes. Efficient implementations have been developed for the proposed methods. On the theoretical side, we offer a novel statistical learning theory and show a fast convergence rate of the excess $\ell$-risk of our methods with emphasis on diverging dimensionality and number of classes. The results can be further improved under a low noise assumption. A set of comprehensive simulation and real data studies has shown the usefulness of the new learning tools compared to regular multicategory classifiers. Detailed proofs of theorems and extended numerical results are included in the supplemental materials available online.Comment: A revised version of this paper was accepted for publication in the Journal of the American Statistical Association Theory and Methods Section. 52 pages, 6 figure

Energy Efficiency Analysis of Heterogeneous Cache-enabled 5G Hyper Cellular Networks

The emerging 5G wireless networks will pose extreme requirements such as high throughput and low latency. Caching as a promising technology can effectively decrease latency and provide customized services based on group users behaviour (GUB). In this paper, we carry out the energy efficiency analysis in the cache-enabled hyper cellular networks (HCNs), where the macro cells and small cells (SCs) are deployed heterogeneously with the control and user plane (C/U) split. Benefiting from the assistance of macro cells, a novel access scheme is proposed according to both user interest and fairness of service, where the SCs can turn into semi- sleep mode. Expressions of coverage probability, throughput and energy efficiency (EE) are derived analytically as the functions of key parameters, including the cache ability, search radius and backhaul limitation. Numerical results show that the proposed scheme in HCNs can increase the network coverage probability by more than 200% compared with the single- tier networks. The network EE can be improved by 54% than the nearest access scheme, with larger research radius and higher SC cache capacity under lower traffic load. Our performance study provides insights into the efficient use of cache in the 5G software defined networking (SDN)

Sustaining export-oriented value chains of farmed seafood in China

This thesis is intended to improve the understanding of China’s evolving export-oriented farmed seafood systems, and in particularly, shrimp and tilapia farming value chains in Southern China. An integrated, systems thinking and interdisciplinary approach in which both top–down and bottom–up approaches were combined. The research moved from system reviews, to field surveys and workshops, and then to improving sustainability by Action Research (AR), in order to form a holistic understanding of sustainability at both national and local scales. In the new millennium, the aquaculture sector has matured, and many factors now slow the growth rate of Chinese aquaculture production, such as increasing culture of high-value species and an emerging trend of extensification. There are been some strategy shifts in the aquaculture industry such as changing from a high production to high profit orientation and from causing environmental damage to ecological remediation. A key conclusion is that high growth rates, regularly used in policy dialogues, are misleading indicators and do not reflect, realistic or sustainable, growth profiles. Although overall Chinese aquaculture production is likely to further increase to meet an increasing and changing market demand, growth rates will decrease further. China already is and will continue to be a fisheries products net importer, however, if fishmeal excluded China will remain as a seafood net exporter. The status and development of four internationally-traded farmed seafood, tilapia, penaeid shrimp, macrobrachium prawns and striped catfish in China were reviewed. China is the largest producer of tilapia, penaeid shrimp and macrobrachium prawns, and striped catfish is not produced in significant quantities due to climate limitations. Meanwhile, China is the largest exporter of tilapia, the second largest exporter in the volume and third in value of shrimp in the world, while macrobrachium prawns mainly support domestic markets. Tilapia and penaeid shrimp were selected for further research. An analysis of tilapia and shrimp farm scale indicators and their relationship to farming system and market orientation, farm intensification and performance was made. Farm area, both land and water area, labour, including paid and unpaid were effective indicators to distinguish farm scale. Small-scale farms had higher land productivity in production terms but no difference in value output term, and they had much lower labour productivity than medium and large-scale farms. Farming systems were also correlated with land and labour productivities. Market orientation was closely linked to farm scale as most farms with an export orientation required registration with CIQ (China Entry-Exit Inspection and Quarantine) and were mainly large-scale. An assessment of local stakeholder sustainability perspectives along value chains revealed that more than 80% shrimp and tilapia farmers didn’t want their children to continue basing their living on aquaculture; because they considered it hard work, high risk and poorly remunerated. Farming was comparative stable with few changes in the five years prior to the survey. Major sustainability factors identified by stakeholders included input costs, profit, water availability & quality and the weather, most of which were outside their control. The measurement of these sustainability factors was firstly proposed by stakeholders and then developed to a set of sustainability indicators (SIs). Life cycle assessment (LCA) was used as evaluate the environmental performance of tilapia, pig and integrated tilapia-pig farming systems in China. Pig farming had higher environment impacts based on most impact categories than tilapia, and integrated farming systems. Sensitivity analysis showed that improvements of 5% and 10% higher feed efficiency, reduction of fishmeal in feed to 1% level and use of EU electricity could significant reduce overall environmental impacts. An action research (AR) approach was used to assess the practice of farm record keeping with farmers which were found to be generally low and a major constraint to improving product traceability increasingly demanded by consumers. Large scale and CIQ farms were more likely to keep records and for them to be detailed and analysed to inform improved management. Farmers’ motivation, ability and capability and background had significant correlation with record keeping practice. Two major dilemmas were identified by the analysis. Easy-to-use farm record-keeping system more suitable for less formally educated farmers was a clear requirement but useful storage and analysis of farm data capacity requires sophisticated management tools such as a computer system. Another dilemma is the need for coercion by regulatory authorities or encouragement through provision of education and training in increasing on-farm record-keeping to a level required for international trade and, increasingly, domestic markets. “Precision aquaculture”, value chain integrated solution, and further social-economic reforms were discussed. Finally, sustainable intensification, diversification, and extensification were proposed as strategies for China to meet the challenges of globalization and the growing demands of export and domestic value chains. In order to enhance sustainability of the sector and provide opportunities for small-scale farmers, the current status and changes of the Chinese social, economic context, food safety and environments issues were discussed. Farmers’ organizations, future consolidation, and land reforms were identified as key to the required changes of farmed seafood value chains

Decide vaccine prices and subsidies for developing countries

Vaccination has been deemed the most cost-effective way to fight against preventable diseases and improve global health. In recent years, expensive combination vaccines which provide multiple antigens in a single shot have been developed to replace traditional monovalent vaccines and have become the preferred choice of healthcare systems in industrialized countries. High prices have not only barricaded low-income countries from accessing combination vaccines but also lure vaccine manufacturers to shift their production capacity from making traditional vaccines to combination vaccines. Such a shift could eventually lead to shortages on the vaccine supply for low-income countries. This work extends the ABP model proposed by Proaño which optimally prices vaccines under tiered pricing strategy to make them affordable and available across different market segments. This thesis first introduces a heuristic method to solve the ABP. Second, this thesis presents an optimization model to decide the minimum amount of subsidy needed to make an expensive combination vaccine affordable to people in a low-income country

Exploratory study on high-performance concrete for bridge decks in West Virginia

This study is intended to provide guidelines for a future global effort on the development of HPC mixes in West Virginia using several types of available aggregates. The objective of the present study is to explore the performance of two types of mixtures using fly ash and slag, respectively, and the same limestone coarse aggregate, natural sand, and constant water/cementitious ratio. For each type, three mixtures were evaluated, with one of the three being defined according to the WVDOT-DOH specifications as a reference (20% fly ash and 30% slag by weight of total cementitious material), from which we varied the quantity of fly ash or slag by +/-5% to define the remaining two. Both fresh and hardened concrete properties were evaluated, and the parameters of interest were compressive strength, drying shrinkage, freeze-thaw durability and chloride permeability, which were not affected much by using higher fly ash or slag content. However, when using higher quantity of slag (35%), the chloride permeability was reduced by nearly 20%. Thus, in future studies, the mixture designs with higher slag and even fly ash content may provide better performance. The best mixture for each type will serve as a foundation for the future optimizations of HPC mix designs in WV