Metrology State-of-the-Art and Challenges in Broadband Phase-Sensitive Terahertz Measurements

The two main modalities for making broadband phase-sensitive measurements at terahertz (THz) frequencies are vector network analyzers (VNA) and time-domain spectrometers (TDS). These measuring instruments have separate and fundamentally different operating principles and methodologies, and they serve very different application spaces. The different architectures give rise to different measurement challenges and metrological solutions. This article reviews these two measurement techniques and discusses the different issues involved in making measurements using these systems. Calibration, verification, and measurement traceability issues are reviewed, along with other major challenges facing these instrument architectures in the years to come. The differences in, and similarities between, the two measurement methods are discussed and analyzed. Finally, the operating principles of electro-optic sampling (EOS) are briefly discussed. This technique has some similarities to TDS and shares application space with the VNA

Investigation of Void Fraction Schemes for Use with CFD-DEM Simulations of Fluidized Beds

© 2018 American Chemical Society. This paper investigates the spatial resolution of computational fluid dynamics-discrete element method (CFD-DEM) simulations of a bubbling fluidized bed for seven different void fraction schemes. Fluid grids with cell sizes of 3.5, 1.6, and 1.3 particle diameters were compared. The particle velocity maps from all of the void fraction schemes were in good qualitative agreement with the experimental data collected using magnetic resonance imaging (MRI). Refining the fluid grid improved the quantitative agreement due to a more accurate representation of flow near the gas distributor. The approach proposed by Khawaja et al. [ J. Comput. Multiphase Flows 2012, 4, 183-192 ] provided the closest match to the exact void fraction though only the particle centered method differed significantly. These results indicate that the fluid grid used for CFD-DEM simulations must be sufficiently fine to represent the inlet flow realistically and that a void fraction scheme such as that proposed by Khawaja be used

How many independent bets are there?

The benefits of portfolio diversification is a central tenet implicit to modern financial theory and practice. Linked to diversification is the notion of breadth. Breadth is correctly thought of as the number of in- dependent bets available to an investor. Conventionally applications us- ing breadth frequently assume only the number of separate bets. There may be a large discrepancy between these two interpretations. We uti- lize a simple singular-value decomposition (SVD) and the Keiser-Gutman stopping criterion to select the integer-valued effective dimensionality of the correlation matrix of returns. In an emerging market such as South African we document an estimated breadth that is considerably lower than anticipated. This lack of diversification may be because of market concentration, exposure to the global commodity cycle and local currency volatility. We discuss some practical extensions to a more statistically correct interpretation of market breadth, and its theoretical implications for both global and domestic investors.Comment: Less technical rewrite. 12 Pages, 6 Figures (.eps

Does lending behaviour of banks in emerging economies vary by ownership? Evidence from the Indian banking sector

While much has been discussed about the relationship between ownership and financial performance of banks in emerging markets, literature about cross-ownership differences in credit market behaviour of banks in emerging economies is sparse. Using bank-level data from India, and a portfolio-choice model, for nine years (1995-96 to 2003-04), we examine banks’ behaviour in the context of emerging credit markets. Our results indicate that, in India, the data for the domestic banks fit well the aforementioned portfolio-choice model, especially for private banks, but the model cannot explain the behaviour of foreign banks. In general, allocation of assets between risk-free government securities and risky credit is affected by past allocation patterns, stock exchange listing (for private banks), risk averseness of banks, regulations regarding treatment of NPA, and ability of banks to recover doubtful credit. It is also evident that banks deal with changing levels of systematic risk by altering the ratio of securitized to non-securitized credit. These results have implications for disbursal of credit to small and medium enterprises in India

Local food systems: concepts, impacts, and issues

Consumer demand for food that is locally produced,marketed, and consumed is generating increased interest in local food throughout the United States. As interest grows, so do questions about what constitutes local food and what characterizes local food systems. What Is the Issue? This study provides a comprehensive literature-review-based overview of the current understanding of local food systems, including: alternative defi nitions; estimates of market size and reach; descriptions of the characteristics of local food consumers and producers; and an examination of early evidence on the economic and health impacts of such systems. What Did the Study Find? There is no generally accepted definition of “local” food. Though “local” has a geographic connotation, there is no consensus on a definition in terms of the distance between production and consumption. Definitions related to geographic distance between production and sales vary by regions, companies, consumers, and local food markets. According to the definition adopted by the U.S. Congress in the 2008 Food, Conservation, and Energy Act,the total distance that a product can be transported and still be considered a “locally or regionally produced agricultural food product” is less than 400 miles from its origin, or within the State in which it is produced. Definitions based on market arrangements, including direct-to-consumer arrangements such as regional farmers’ markets, or direct-to-retail/foodservice arrangements such as farm sales to schools, are well-recognized categories and are used in this report to provide statistics on the market development of local foods. Local food markets account for a small but growing share of total U.S. agricultural sales. • Direct-to-consumer marketing amounted to $1.2 billion in current dollar sales in 2007, according to the 2007 Census of Agriculture, compared with$551 million in 1997. • Direct-to-consumer sales accounted for 0.4 percent of total agricultural sales in 2007, up from 0.3 percent in 1997. If nonedible products are excluded from total agricultural sales, direct-to consumer sales accounted for 0.8 percent of agricultural sales in 2007. • The number of farmers’ markets rose to 5,274 in 2009, up from 2,756 in 1998 and 1,755 in 1994, according to USDA’s Agricultural Marketing Service. • In 2005, there were 1,144 community-supported agriculture organizations, up from 400 in 2001 and 2 in 1986, according to a study by the National Center for Appropriate Technology. In early 2010, estimates exceeded 1,400, but the number could be much larger. • The number of farm to school programs, which use local farms as food suppliers for school meals programs and promote relationships between schools and farms, increased to 2,095 in 2009, up from 400 in 2004 and 2 in the 1996-97 school year, according to the National Farm to School Network. Data from the 2005 School Nutrition and Dietary Assessment Survey, sponsored by USDA’s Food and Nutrition Service, showed that 14 percent of school districts participated in Farm to School programs, and 16 percent reported having guidelines for purchasing locally grown produce. Production of locally marketed food is more likely to occur on small farms located in or near metropolitan counties. Local food markets typically involve small farmers, heterogeneous products, and short supply chains in which farmers also perform marketing functions, including storage, packaging, transportation, distribution, and advertising. According to the 2007 U.S. Census of Agriculture, most farms that sell directly to consumers are small farms with less than $50,000 in total farm sales, located in urban corridors of the Northeast and the West Coast. In 2007, direct-to-consumer sales accounted for a larger share of sales for small farms, as defi ned above, than for medium-sized farms (total farm sales of$50,000 to $499,999) and large farms (total farm sales of$500,000 or more). Produce farms engaged in local marketing made 56 percent of total agricultural direct sales to consumers, while accounting for 26 percent of all farms engaged in direct-to-consumer marketing. Direct-to-consumer sales are higher for the farms engaged in other entrepreneurial activities, such as organic production, tourism, and customwork (planting, plowing, harvesting, etc. for others), than for other farms. In 2007, direct sales by all U.S. farms surpassed customwork to become the leading on-farm entrepreneurial activity in terms of farm household participation. Barriers to local food-market entry and expansion include: capacity constraints for small farms and lack of distribution systems for moving local food into mainstream markets; limited research, education, and training for marketing local food; and uncertainties related to regulations that may affect local food production, such as food safety requirements. Consumers who value high-quality foods produced with low environmental impact are willing to pay more for locally produced food. Several studies have explored consumer preferences for locally produced food. Motives for “buying local” include perceived quality and freshness of local food and support for the local economy. Consumers who are willing to pay higher prices for locally produced foods place importance on product quality, nutritional value, methods of raising a product and those methods’ effects on the environment, and support for local farmers. Federal, State, and local government programs increasingly support local food systems. Many existing government programs and policies support local food initiatives, and the number of such programs is growing. Federal policies have grown over time to include the Community Food Project Grants Program, the WIC Farmers’ Market Nutrition Program, Senior Farmers’ Market Nutrition Program, Federal State Marketing Improvement Program, National Farmers’ Market Promotion Program, Specialty Crop Block Grant Program, and the Community Facilities Program. State and local policies include those related to farm-to-institution procurement, promotion of local food markets, incentives for low-income consumers to shop at farmers’ markets, and creation of State Food Policy Councils to discuss opportunities and potential impact of government intervention. (WIC is the acronym for the Special Supplemental Nutrition Program for Women, Infants, and Children). As of early 2010, there were few studies on the impact of local food markets on economic development, health, or environmental quality. • Empirical research has found that expanding local food systems in a community can increase employment and income in that community. • Empirical evidence is insuffi cient to determine whether local food availability improves diet quality or food security. • Life-cycle assessments—analyses of energy use at all stages of the food system including consumption and disposal—suggest that localization can but does not necessarily reduce energy use or greenhouse gas emissions. How Was the Study Conducted? Existing analyses of local food markets by universities, government agencies, national nonprofit organizations, and others of local food markets were synthesized to evaluate the definition of local foods and the effects of local food systems on economic development, health and nutrition, food security, and energy use and greenhouse gas emissions. The report’s content relies on data collected through the 2007 Census of Agriculture, as well as other surveys by USDA’s Agricultural Marketing Service, the National Farm to School Network, university extension departments, and others, to provide a comprehensive picture of types of local food markets, their characteristics, and their importance over time.Local food systems; farmers’ markets; direct-to-consumer marketing; direct-to-retail/foodservice marketing; community supported agriculture; farm to school programs; Farmers’ Market Promotion Program; food miles; ERS; USDA

The potential role of variations in juvenile hip geometry on the development of Legg-Calvé-Perthes disease: a biomechanical investigation

© 2018 Informa UK Limited, trading as Taylor & Francis Group Legg-Calvé-Perthes disease (LCP) is one of the most poorly understood diseases in paediatric orthopaedics. One common trait of LCP is the marked morphological difference between healthy and pathological hips, early deviations of which (i.e. prior to disease onset) have been suggested to lead to the overload and collapse of the epiphysis. Here, the impact of common variations in geometry is investigated with a finite element model of a juvenile femur under single leg standing and landing. Here, the impact of typical variations in geometry is investigated with a finite element model of a juvenile femur under single leg standing and landing. The variations appear to have only a limited effect on the stress distribution in the femoral epiphysis even during high impact activities. This suggests that, for this individual at least, they would be unlikely to cause epiphyseal overload and collapse, even in the presence of a skeletally immature epiphysis

Public experiences of mass casualty decontamination

In this article, we analyze feedback from simulated casualties who took part in field exercises involving mass decontamination, to gain an understanding of how responder communication can affect people’s experiences of and compliance with decontamination. We analyzed questionnaire data gathered from 402 volunteers using the framework approach, to provide an insight into the public’s experiences of decontamination and how these experiences are shaped by the actions of emergency responders. Factors that affected casualties’ experiences of the econtamination process included the need for greater practical information and better communication from responders, and the need for privacy. Results support previous findings from small-scale incidents that involved decontamination in showing that participants wanted better communication from responders during the process of decontamination, including more practical information, and that the failure of responders to communicate effectively with members of the public led to anxiety about the decontamination process. The similarity between the findings from the exercises described in this article and previous research into real incidents involving decontamination suggests that field exercises provide a useful way to examine the effect of responder communication strategies on the public’s experiences of decontamination. Future exercises should examine in more detail the effect of various communication strategies on the public’s experiences of decontamination. This will facilitate the development of evidence-based communication strategies intended to reduce anxiety about decontamination and increase compliance among members of the public during real-life incidents that involve mass decontamination

nSharma: Numerical Simulation Heterogeneity Aware Runtime Manager for OpenFOAM

CFD simulations are a fundamental engineering application,implying huge workloads, often with dynamic behaviour due to run-time mesh refinement. Parallel processing over heterogeneous distributedmemory clusters is often used to process such workloads. The executionof dynamic workloads over a set of heterogeneous resources leads to loadimbalances that severely impacts execution time, when static uniformload distribution is used. This paper proposes applying dynamic, het-erogeneity aware, load balancing techniques within CFD simulations.nSharma, a software package that fully integrates with OpenFOAM, ispresented and assessed. Performance gains are demonstrated, achievedby reducing busy times standard deviation among resources, i.e. hetero-geneous computing resources are kept busy with useful work due to aneffective workload distribution. To best of authors’ knowledge, nSharmais the first implementation and integration of heterogeneity aware loadbalancing in OpenFOAM and will be made publicly available in order tofoster its adoption by the large community of OpenFOAM users.The authors would like to thank the financial funding by FEDER through the COMPETE 2020 Program, the National Funds through FCT under the projects UID/CTM/50025/2013. The first author was partially funded by the PT-FLAD Chair on Smart Cities & Smart Governance and also by the School of Engineering, University of Minho within project Performance Portability on Scalable Heterogeneous Computing Systems. The authors also wish to thank Kyle Mooney for making available his code supporting migration of dynamically refined meshes, as well as acknowledge the Texas Advanced Computing Center (TACC) at The University of Texas at Austin for providing HPC resources