DEVELOPMENT OF AN ACCEEPTABILITY CONSTRAINT FOR A LINEAR PROGRAMMING MODEL IN FOOD FORMULATION

Control of a product's market acceptability can be a difficulty when using linear programming models in food formulation. The development of an acceptability constraint was demonstrated for a linear programming model used for the formulation of fresh turkey bratwurst, a coarse ground type sausage. Development was in two stages. First, an experimental design and in-house panel determined quantitative relationships between the product's textural attributes and turkey meat ingredients. Second, the product toughness relationship was utilized to develop three formulations with different levels of toughness. These formulations were market tested using the acceptor set size as the measure of market acceptability. A relationship between product toughness and acceptor set size was determined, into which was substituted the toughness f (ingredients) relationship. This yielded acceptor set size as a f (ingredients) that was added to the least cost linear programming model in the form of an acceptability constraint.     

Setting Single-Period Optimal Capacity Levels and Prices for Substitutable Products

In this paper, we consider how a company that has the flexibility to produce two substitutable products would determine optimal capacity levels and prices for these products in a single-period problem. We first consider the case where the firm is a price taker but can determine optimal capacity levels for both products. We then consider the case where the firm can set the price for one product and the optimal capacity level for the other. Finally, we consider the case where capacity is fixed for both products, but the firm can set prices. For each case, we examine the sensitivity of optimal prices and capacities to the problem parameters. Finally, we consider the case where each product is managed by a product manager trying to maximize individual product profits rather than overall firm profits and analyze how optimal price and capacity decisions are affected.     

An Approach to Integrating Environmental Considerations Within Managerial Decision‐Making

Recent environmental trends, including (1) an expansion of existing command and control directives, (2) the introduction of market‐based policy instruments, and (3) the adoption of extended producer responsibility, have created a need for new tools to help managerial decision‐making. To address this need, we develop a nonlinear mathematical programming model from a profit‐maximizing firm's perspective, which can be tailored as a decision‐support tool for firms facing environmental goals and constraints. We typify our approach using the specific context of diesel engine manufacturing and remanufacturing. Our model constructs are based on detailed interviews with top managers from two leading competitors in the medium and heavy‐duty diesel engine industry. The approach allows the incorporation of traditional operations‐planning considerations—in particular, capacity, production, and inventory—together with environmental considerations that range from product design through production to product end of life. A current hurdle to implementing such a model is the availability of input data. We therefore highlight the need not only to involve all departments within businesses but also for industrial ecologists and business managers to work together to implement meaningful decision models that are based on accurate and timely data and can have positive economic and environmental impact.     

Impact considerations of post-production processes on cell and gene drug products

Cell and gene therapies are demonstrating clinical efficacy, but prohibitive product costs and operational complexity bottlenecks may limit expanded patient access to these innovative and transformative products. An initial survey and subsequent article published through the International Society for Cell & Gene Therapy in 2017 presented a roadmap on how specific steps, from tissue procurement and material acquisition to facility operation and production, contribute to the high cost of cell and gene therapies. Herein the authors expanded the investigation to provide considerations to better understand how post-production procedures can impact a product's accessibility to patients. The administration of a drug product to and follow-up in a patient involve key decisions in several post-production process areas, such as product storage, distribution and handling logistics and compliance, across the value chain through integrated data management solutions. Understanding as well as carefully evaluating these specific components is not widely considered during early process development but is critical in developing a viable product life cycle.     

A freight network planning model in oligopolistic shipping markets

The paper presents a multi-level hierarchical approach which models the oligopolistic behavior of carriers in maritime freight transportation networks. With the merger of the carriers’ industry and some dominant carriers in today’s shipping markets, carrier competition frequently exhibits an oligopolistic nature. This study considers the following three types of carriers; ocean carriers, land carriers, and port terminal operators. The oligopolistic ocean carriers, land carriers, and port terminal operators compete with each other in their pricing and routing decisions. The carriers determine service charges and delivery routes at different parts of the multi-modal freight network, creating hierarchical relationships. When using a game theoretic approach, ocean carriers become the leaders in an oligopoly shipping market. When dealing with individual carrier problems, the Nash equilibrium reveals the optimal decision where each carrier obtains the greatest profit. A three-level model is formulated to capture the interactions among different types of carriers. The validity and capability of the model gets demonstrated through an empirical example.     

SURVIVAL ANALYSIS TO ESTIMATE SENSORY SHELF LIFE USING ACCEPTABILITY SCORES

ABSTRACT

In the present study, survival analysis was applied on consumers' acceptability scores, focusing the shelf‐life risk on the consumers disliking the product. Shelf life was estimated as the time necessary to reach a fixed percentage of consumers disliking the product, that is, the percentage of consumers scoring the product's overall acceptability below 6 in a 9‐point hedonic scale. In the present work, this methodology was applied to estimate the sensory shelf life of whole pan bread and alfajores. Shelf lives estimated considering 50% of the consumers disliking the product were shorter than those estimated considering consumers' rejection to consume. These results suggest that a proportion of consumers might dislike the sample but still answer “yes” when asked if they would consume the product at their homes. This could be attributed to the fact that when consumers are asked whether they would consume the product, they might think about consuming it after being stored at their homes. In this situation, consumers might be more tolerant toward sensory defects because they do not want to discard the product.

PRACTICAL APPLICATIONS

Sensory shelf life can be estimated using survival analysis considering the percentage of consumers disliking the product. This methodology seems to be a conservative criterion in order to assure the product's quality throughout its storage.     

Light and storage time influence the microbial quality of minimally processed rocket

Ready-to-eat minimally processed fruits and vegetables are an ideal substrate for the growth of microorganisms, including human pathogens and mycotoxin-producing species, which question their quality and safety for customers. While we are aware of the importance of production workflows in structuring the products' microbial communities, we still know little about the factors that shape microbiomes during the timeframe products are available to customers, and beyond this timeframe. Here, we study the influence of storage light condition (light or dark) on microbiological and physico-chemical parameters of minimally processed rocket leaves at different shelf life timepoints (the day the product becomes available to consumers, expiration date, 3 days after the expiration date). Our results suggest that the total microbial load increases from the day the product becomes available to consumers, to the expiry date and after the product's expiration. However, when studying the composition of the fungal microbiome, we did not observe significant changes in its structure as the effect of product shelf life or storage light condition. We also found that products stored under light condition had a higher total bacterial load compared to those stored in darkness. Our results might be helpful in crafting improved workflows for product's storage during its shelf life, which might ultimately lead to a re-evaluation of storage times resulting in reduced food waste due to product spoilage or expiration.     

Estimating Environmental Behavior Without Performing a Life Cycle Assessment

Many authors have agreed on the interest of considering environmental concerns in the early stages of product development. However, most eco‐design tools are based on life cycle assessment principles and require a model to give information about the product's environmental performance. This modeling can have negative effects on team performance and on the potential for innovation, not to mention on the project's duration. Additionally, the model requires information that is not available in the early design stages. This article analyzes the potential of inferring conclusions about the life cycle stages with the highest impact by using similar products. From a database of previous products, environmental profile estimations are carried out, that is, the assessments of the contribution of each life cycle stage to the total impact and the variability of this measure. It is then possible to discard—or ensure consideration of—life cycle stages. Furthermore, the level of the conclusions is assessed on a five‐point scale. The proposed approach is applied to four case studies with different levels of abstraction and the relevance of the conclusions is assessed. The article resolves the problems regarding potential for estimating the distribution of the environmental impacts along the life cycle.     

A Cross-Sectional Analysis of Variation in Charges and Prices across California for Percutaneous Coronary Intervention

Background

Though past studies have shown wide variation in aggregate hospital price indices and specific procedures, few have documented or explained such variation for distinct and common episodes of care.

Objectives

We sought to examine the variability in charges for percutaneous coronary intervention (PCI) with a drug-eluting stent and without major complications (MS-DRG-247), and determine whether hospital and market characteristics influenced these charges.

Methods

We conducted a cross-sectional analysis of adults admitted to California hospitals in 2011 for MS-DRG-247 using patient discharge data from the California Office of Statewide Health Planning and Development. We used a two-part linear regression model to first estimate hospital-specific charges adjusted for patient characteristics, and then examine whether the between-hospital variation in those estimated charges was explained by hospital and market characteristics.

Results

Adjusted charges for the average California patient admitted for uncomplicated PCI ranged from $22,047 to $165,386 (median: $88,350) depending on which hospital the patient visited. Hospitals in areas with the highest cost of living, those in rural areas, and those with more Medicare patients had higher charges, while government-owned hospitals charged less. Overall, our model explained 43% of the variation in adjusted charges. Estimated discounted prices paid by private insurers ranged from $3,421 to $80,903 (median: $28,571).

Conclusions

Charges and estimated discounted prices vary widely between hospitals for the average California patient undergoing PCI without major complications, a common and relatively homogeneous episode of care. Though observable hospital characteristics account for some of this variation, the majority remains unexplained.     

Endogenous Price Bubbles in a Multi-Agent System of the Housing Market

Economic history shows a large number of boom-bust cycles, with the U.S. real estate market as one of the latest examples. Classical economic models have not been able to provide a full explanation for this type of market dynamics. Therefore, we analyze home prices in the U.S. using an alternative approach, a multi-agent complex system. Instead of the classical assumptions of agent rationality and market efficiency, agents in the model are heterogeneous, adaptive, and boundedly rational. We estimate the multi-agent system with historical house prices for the U.S. market. The model fits the data well and a deterministic version of the model can endogenously produce boom-and-bust cycles on the basis of the estimated coefficients. This implies that trading between agents themselves can create major price swings in absence of fundamental news.     

A matter of timing: System requirements for repair and their temporal dimensions

Research into repair within the circular economy (CE) typically focuses on technical aspects of design, policy, and markets, and often assumes simplified conditions for the user/owner and the product system to explain the barriers to scaling repair activities. However, factors occurring at pre-use stages of the product's life cycle can significantly influence whether, and to what extent, repair is viable or possible, that is, warranty duration, after-sale service provision, and access to necessities. The passing of time can directly and indirectly affect the ability, difficulty, and thus, the likelihood of repair activities being performed at each stage of the product's life cycle. Drawing from the literature and applying inductive systems-thinking tools, we propose a framework for considering the “System of Repairability.” We delineate how the passing of time (temporal dimensions) affects one's ‘‘ability to repair,’’ as a product progresses through different life cycle phases (i.e., breakdown vs. repair vs. disposal), and the point(s) at which the repair is considered or attempted (i.e., year of usage). By integrating life cycle and temporal (time-based) dimensions into a broad System of Repairability framework, we clarify relevant interconnections, iterations, sequences, and timing of decision points, stakeholders, and necessary conditions to facilitate an outcome of successful repair at the individual level, and thus intervention strategies for scaling repair within CE. We discuss how a policy mix can address the life cycle of products and the repair system more holistically. We conclude with a future outlook on how temporal dimensions can inform policy strategies and future research.     

Prospective Environmental Analyses of Emerging Technology: A Critique,a Proposed Methodology,and a Case Study on Incremental Sheet Forming

Prospective environmental assessment of emerging technology is necessary in order to inform designers of beneficial changes early in a technology's development, and policy makers looking to fund projects and nudge manufacturers toward the most sustainable application of a technology. Existing analyses often have shortcomings such as failing to consider the environmental impacts in all stages of a product's life cycle; implicitly assuming that the emerging technology will be cost‐effective wherever it is technically viable; and assuming optimistic application scenarios that discontinue long‐established trends in human behavior. In this article, we propose a new approach, complementary to the prospective and anticipatory life cycle assessment literature, addressing the above concerns and attempting to make sense of the large uncertainties inherent in such analyses by using distributions to model all the inputs. The paper focuses on emerging manufacturing technologies, such as incremental sheet forming (ISF), but the issues examined are also applicable to new end‐use products, such as autonomous vehicles. This paper makes use of approaches (such as Bass modeling and product cannibalization considerations) familiar to those in the business community who anticipate market diffusion of a new technology and the effect on existing technology sales. The proposed methodology is demonstrated by estimating the potential environmental impacts in the U.S. car industry by 2030 of an emerging double‐sided ISF process. Energy and cost models of ISF and drawing are used to estimate potential mean savings of around 100 TJ_primary and 60 million U.S. dollars per year by 2030.     

Simulation of movement and egglaying inDanaus plexippus (Lepidoptera: Nymphalidae)

A model simulating the movement and oviposition of monarch butterflies over a female's life time is presented. The model's predictions compare favourably with observed data and suggest that females who lay eggs in an optimal fashion should have low directionalities in areas with high host plant density (patches and single plants) and high directionalities in areas with low host plant density. The model also provides one means of combining individual animal processes and spatial heterogeneity into population dynamics.     

Does It Really Pay to Be Green? An Empirical Study of Firm Environmental and Financial Performance: An Empirical Study of Firm Environmental and Financial Performance

Previous empirical work suggests that firms with high environmental performance tend to be profitable, but questions persist about the nature of the relationship. Does stronger environmental performance really lead to better financial performance, or is the observed relationship the outcome of some other underlying firm attribute? Does it pay to have cleanrunning facilities or to have facilities in relatively clean industries? To explore these questions, we analyze 652 U.S. manufacturing firms over the time period 1987–1996. Although we find evidence of an association between lower pollution and higher financial valuation, we find that a firm's fixed characteristics and strategic position might cause this association. Our findings suggest that “When does it pay to be green?” may be a more important question than “Does it pay to be green?”     

Process flexibility and inventory flexibility via product substitution

This paper studies the optimal control of and interaction between two types of flexibility under Markov models of demand and production: process flexibility and inventory flexibility. In our model, process flexibility is generated by a multi-functional production facility that can produce two types of products, and inventory flexibility is manifested in firm-driven one-way product substitution. Both process flexibility and inventory flexibility are important drivers of supply chain performance and are strategic design considerations. To analyze the interaction between these two types of flexibility, we model a dynamically controlled two-product, make-to-stock system with stochastic processing times and stochastic demand. We characterize the complex joint optimal production and post-production policy for a special case and numerically show that a simply structured multi-threshold policy is a near-optimal heuristic policy for the general case. We gain further insight into the impact of system parameters on the value of process flexibility and inventory flexibility via a comprehensive numerical study. We find that for a wide range of capacity and cost parameters, process flexibility and inventory flexibility complement each other, so pursuing both forms of flexibility is effective.     

Enhancement of asymmetric bioreduction of ethyl 4-chloro acetoacetate by the design of composition of culture medium and reaction conditions

This study investigated the feasibility of improving the stereospecificity of yeast by the adjustment of the culture medium composition and the reaction conditions. The investigation was performed systematically, using an approach that integrates the Taguchi's array method and the steepest ascent method. The reaction yield and the product's ee were the two indexes of reaction performance. A desirability function was applied to combine these two indexes as a single objective function. The removal of peptone and malt extract from the YM medium increased the yeast's stereoselectivity, without reducing the production of biomass. The medium composition and the reaction conditions were then simultaneously optimized. The resulting optimal conditions were 30 g/l glucose for cultivation, 12 g/l yeast extract, a cultivation time of 12 h, 15 g/l glucose for reaction, 150 g/l yeast for reaction, a reaction buffer concentration of 0.2 M and a buffer pH of 8.5. Compared to the one before this study, the product's ee was improved from 82.1 to 92.3%, and the reaction yield was enhanced from 77.3 to 82.3%. Furthermore, the biomass production was increased considerably from 5.94 to 10.14 g DCW/l.     

2015年度中国医药市场发展蓝皮书——产业经济部分 （ Ⅰ ）

从产业经济角度,包括医药工业总产值、医药工业销售收入、医药工业盈利水平、医药流通行业销售规模、医药商业效益水平、     

Time to Pregnancy: A Computational Method for Using the Duration of Non-Conception for Predicting Conception

An important problem in reproductive medicine is deciding when people who have failed to become pregnant without medical assistance should begin investigation and treatment. This study describes a computational approach to determining what can be deduced about a couple''s future chances of pregnancy from the number of menstrual cycles over which they have been trying to conceive. The starting point is that a couple''s fertility is inherently uncertain. This uncertainty is modelled as a probability distribution for the chance of conceiving in each menstrual cycle. We have developed a general numerical computational method, which uses Bayes'' theorem to generate a posterior distribution for a couple''s chance of conceiving in each cycle, conditional on the number of previous cycles of attempted conception. When various metrics of a couple''s expected chances of pregnancy were computed as a function of the number of cycles over which they had been trying to conceive, we found good fits to observed data on time to pregnancy for different populations. The commonly-used standard of 12 cycles of non-conception as an indicator of subfertility was found to be reasonably robust, though a larger or smaller number of cycles may be more appropriate depending on the population from which a couple is drawn and the precise subfertility metric which is most relevant, for example the probability of conception in the next cycle or the next 12 cycles. We have also applied our computational method to model the impact of female reproductive ageing. Results indicate that, for women over the age of 35, it may be appropriate to start investigation and treatment more quickly than for younger women. Ignoring reproductive decline during the period of attempted conception added up to two cycles to the computed number of cycles before reaching a metric of subfertility.     

DELETERIOUS MUTATION AND THE EVOLUTION OF GENETIC LIFE CYCLES

It is often proposed that the ability of diploids to mask deleterious mutations leads to an evolutionary advantage over haploidy. In this paper, we studied the evolution of the relative duration of haploid and diploid phases using a model of recurrent deleterious mutations across the entire genome. We found that a completely diploid life cycle is favored under biologically reasonable conditions, even when prolonging the diploid phase reduces a population's mean fitness. A haploid cycle is favored when there is complete linkage throughout the genome or when mutations are either highly deleterious or partially dominant. These results hold when loci interact multiplicatively and for synergistic epistasis. The strength of selection generated on the life cycle can be substantial because of the cumulative effect of selection against mutations across many loci. We did not find conditions that support cycles that retain both phases, such as those found in some plants and algae. Thus, selection against deleterious mutations may be an important force in the evolution of life cycles but may not be sufficient to explain all the patterns of life cycles seen in nature.