Is low field always better for imaging around passive implants?

Proceedings on CD-ROM - International Society for Magnetic Resonance in Medicine. Scientific Meeting and Exhibition/Proceedings of the International Society for Magnetic Resonance in Medicine, Scientific Meeting and Exhibition · 2024-11-26

Motivation: To investigate the performance of modernized low-field MRI relative to traditional systems for imaging near metallic devices within the clinical context. Goal(s): To evaluate whether low-field MRI can offer a significant reduction in artifacts when using routine clinical protocols. Approach: The artifact characteristics of 0.5 T, 1.5 T, and 3 T MRIs are compared in this ASTM F2119-07-based phantom study of common passive metallic devices. Results: Low-field MRI demonstrated the capability to reduce susceptibility artifacts when imaging near metal-containing medical devices. However, artifact produced by some pulse sequences diverged from the anticipated field-dependence, highlighting the sizable effects of clinical protocolling. Impact: This phantom study demonstrates that low-field MRI can image metallic devices with reduced artifact relative to 1.5/3 T systems using routine clinical protocols, highlighting opportunities for future in vivo studies involving implants and imaging in areas with magnetic susceptibility distortions.

Price Volatility: A Bitter Pill of Trade Liberalization in Agriculture?

2024-11-06

Public sector involvement in the agricultural markets has historically included import quotas, export subsidies, price supports, and supply-oriented measures such as input restrictions or inventory management. From a sector basis, these interventions have most often attempted to enhance prices or to control (symmetrically or asymmetrically) the range of their variation. Since the institution of sector-targeted policies during the Great Depression, agricultural and food markets have evolved substantially, as has the distribution of market power in those markets. Over the past few decades, the wisdom of these roles of government in agricultural markets has been brought to question by their high financial burdens and less than expected efficacy in achieving goals. Further, the high costs of the associated distortions of agricultural trade among nations has been recognized. Together this evolution of thinking concerning the role of government in markets has led to a slow, though persistent progression of changes in policies resulting in an increasingly private, decentralized market orientation at both national and international levels.

Sustainable Management of Remanufacturing in Dynamic Supply Chains

Networks and Spatial Economics · 2020-03-13 · 6 citations

Pricing Perishables: Robust Price Assurance

International journal on food system dynamics · 2020-03-27

As perishable products are worthless at end-of-life, for a given supply prices are often dynamically adjusted to ensure inventory is exhausted at end-of-life. When consumers expect such price reductions, they may strategically time their purchases. These two conditions pose a complex problem for pricing. Given inventory, cost of production is sunk. Thus, the dynamic path for prices must be set to maximize revenues with an eye on inventory take-down as well as to discourage strategic behavior. This problem is further challenged when prices and the extent of consumer strategic behavior are uncertain. This paper presents an approach for pricing a set of perishable products that are highly substitutable, yet differentiated to target a set of consumer segments. We propose and analyze a price assurance scheme as a solution to the strategic behavior of consumers and price uncertainty. We present and evaluate our price assurance approach by comparing two price assurance schemes: i) ex-post price assurance, and ii) ex-ante price assurance to risk neutral dynamic pricing without regard for consumer strategic behavior. These approaches have not to our knowledge been previously considered in our setting of perishables, uncertain consumer strategic behavior, and price uncertainty. Our numerical experiments show that our robust optimization model prevents loss when a firm encounters the worst-case demand and outperforms a risk neutral pricing model. Comparison across our different pricing schemes provides conditions under which particular schemes may dominate others.

Optimal Switching in a Dynamic, Stochastic, Operating Environment

2020-12-14

The value of flexibility in operations for hydroelectric power plants is apparent from their investment in multiple generators to allow variable intensity of operation. This flexibility supports rapid response to outside factors that impact their performance. It follows that hydroelectricity generation often competes for water flow with downstream water demands including irrigation, urban water use, or ecosystem services. Each of these follows stochastic process that implies asynchronous demand for water flow. The associated management problem is of interest encompassing multiple switching and motivating other extensions. This paper considers the dynamic stochastic problem of water allocation for hydroelectric generation and downstream use. Our main contribution is to present a novel numerical solution to this problem. Moreover, the method allows generalization not previously possible including: (i) multiple dynamic stochastic processes with jump diffusions, (ii) the number of contingent decisions with reversibility, and (iii) characterization of risk and uncertainty including dynamic constraints.

Sustainable Management of Remanufacturing in Dynamic Closed-loop Supply Chains

Networks and Spatial Economics · 2020-01-01

Check the Dairy Chain efficiency in Italy

2019-07-30 · 2 citations

This research is an application of the econometric price series to the analysis of dairy chain efficiency in Italy. At a theoretic level, the price transmission and asymmetry in the speed of adjustment to positive and negative price changes is supported by the Industrial Organization, multi market equilibrium, food chain theories. However this does not provide a clear signal of competitiveness as many conditions may induce stickiness (curvature of demand, local cost and externalities, long term contracts,. While evidences from past EU studies about the dairy sector are mixed, several studies have demonstrated the evidence of price asymmetries in different market contests. The aim of this research is to examine the price dynamics along the dairy chain and offer some empirical evidences about the cointegration and asymmetric price transmission at different market levels. The parametric test of asymmetry in a multivariate VECM (vector error correction term), suggests symmetry in co-movement. To explore in deeper whether these results are robust with respect to nonlinearity it is estimated the threshold VECM model; the results suggest to reject the hypothesis of asymmetry with exception for the raw milk and wholesale butter. While market competitiveness can not be inferred only from evidence of asymmetry, these findings support the hypothesis that the market structure and policy in the Italian dairy chain didn’t affect greatly the price asymmetry. However, for the butter market, the public intervention seems to have generated speculative behavior among the operators and generated asymmetric price responses to positive/negative price changes.

Pricing Perishables with Uncertain Demand, Substitutes, and Consumer Heterogeneity

RePEc: Research Papers in Economics · 2019-05-22 · 3 citations

Within the marketing window for perishables such as food products, demand uncertainty is complicated by price sensitivity and propensity to postpone purchase that is heterogeneous across consumers. These features pose substantial challenges to retailers when pricing multiple products over time and across consumer segments. Getting the dynamic profile of prices right has implications for performance of vertical food chains ranging from revenues to food waste. This paper proposes an approach to dynamic pricing that is demonstrated to improve performance within this setting.

Agricultural and oil commodities: price transmission and market integration between US and Italy

AgEcon Search (University of Minnesota, USA) · 2019-09-18 · 10 citations

Purpose of this article it to get some evidences of market interaction between United States and Italy using the time series analysis of spot prices spanning from January 1999 to May 2012 for crude oil and three ag-commodities: wheat, corn and soybean. These crops have been selected for their relevance in ag-commodity exchanges between US and Italy markets. The integration between US and Italy agricultural markets is hypothesized for the consistent volume of crop traded between these two countries while the price transmission is related to the leading price signals of the CBT (Chicago Board of Trade). The integration between oil and ag-commodity markets is suggested both by the large use of energy intensive inputs, (fertilizer, seed, machinery) in production of these ag-commodities, and their use in biofuel production. The results suggest: a) for US market the evidence of market integration between crude oil and US ag-commodities; b) for Italy the integration with US ag-commodity markets and less evidence of integration with the oil market. These results are valuable information both for the agents and policy makers contributing to improve the information accuracy to predict the price movements used by marketing operators for their strategies and policy makers to set up policies to re-establish conditions of market efficiency and allocate these ag-commodities in alternative market channels.

Cultivating Social Capital through Summer Employment Programs

Critical Social Work · 2019-05-30

Significant socio-economic shifts, such as the emergence of the so-called ‘knowledge economy’ have transformed the transition from adolescence to adulthood, as youth are expected to garner a considerable amount of personal, cognitive, social, and educational skills in order to successfully enter adult society and prosper within the market economy. An additional determinant of the successful transition of youth into adult society is the availability of social capital through relationships and networks that can provide access to valuable resources and information and contribute to the development of a social identity. Employment programs are a mechanism for providing youth with workforce exposure and skill development in the absence of market opportunities. These programs are also a potential source of social capital, through the exposure to new environments and the development of relationships and networks that can provide resources that youth may not have access to through traditional means. Using a qualitative approach, we explored the perspectives of youth participants in a summer employment program in Southwestern Ontario, Canada. We propose that the opportunity to develop social capital is an under-recognized benefit of employment programs, and may be a particularly important aspect for disadvantaged youth.