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1. Effect of nutrient supply on cell size evolution of marine phytoplankton

   https://doi.org/10.3934/mbe.2023218  

   Liu, Lidan; Fan, Meng; Kang, Yun (January 2023, Mathematical Biosciences and Engineering)

   The variation of nutrient supply not only leads to the differences in the phytoplankton biomass and primary productivity but also induces the long-term phenotypic evolution of phytoplankton. It is widely accepted that marine phytoplankton follows Bergmann's Rule and becomes smaller with climate warming. Compared with the direct effect of increasing temperature, the indirect effect via nutrient supply is considered to be an important and dominant factor in the reduction of phytoplankton cell size. In this paper, a size-dependent nutrient-phytoplankton model is developed to explore the effects of nutrient supply on the evolutionary dynamics of functional traits associated with phytoplankton size. The ecological reproductive index is introduced to investigate the impacts of input nitrogen concentration and vertical mixing rate on the persistence of phytoplankton and the distribution of cell size. In addition, by applying the adaptive dynamics theory, we study the relationship between nutrient input and the evolutionary dynamics of phytoplankton. The results show that input nitrogen concentration and vertical mixing rate have significant effects on the cell size evolution of phytoplankton. Specifically, cell size tends to increase with the input nutrient concentration, as does the diversity of cell sizes. In addition, a single-peaked relationship between vertical mixing rate and cell size is observed. When the vertical mixing rate is too low or too high, only small individuals are dominant in the water column. When the vertical mixing rate is moderate, large individuals can coexist with small individuals, so the diversity of phytoplankton is elevated. We predict that reduced intensity of nutrient input due to climate warming will lead to a trend towards smaller cell size and will reduce the diversity of phytoplankton. 

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2. Decision model with quantification of buyer-supplier trust in advanced technology enterprises

   https://doi.org/10.1108/BIJ-06-2021-0336  

   Collier, Zachary A.; Guin, Ujjwal; Sarkis, Joseph; Lambert, James H. (December 2021, Benchmarking: An International Journal)

   Purpose In the buyer-supplier relationship of a high-technology enterprise, the concepts of trust and risk are closely intertwined. Entering into a buyer-supplier relationship inherently involves a degree of risk, since there is always an opportunity for one of the parties to act opportunistically. Purchasing and supply managers play an important role in reducing the firm's risk profile, and must make decisions about whether or not to enter into, or remain in, a relationship with a supplier based on a subjective assessment of trust and risk. Design/methodology/approach In this paper, the authors seek to explore how trust in the buyer-supplier relationship can be quantitatively modeled in the presence of risk. The authors develop a model of trust between a buyer and supplier as a risk-based decision, in which a buyer decides to place trust in a supplier, who may either act cooperatively or opportunistically. The authors use a case study of intellectual property (IP) piracy in the electronics industry to illustrate the conceptual discussion and model development. Findings The authors produce a generalizable model that can be used to aid in decision-making and risk analysis for potential supply-chain partnerships, and is both a theoretical and practical innovation. However, the model can benefit a variety of high-technology enterprises. Originality/value While the topic of trust is widely discussed, few studies have attempted to derive a quantitative model to support trust-based decision making. This paper advanced the field of supply chain management by developing a model which relates risk and trust in the buyer-supplier relationship. 

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3. A Mechanism Design Approach to Vendor Managed Inventory

   https://doi.org/10.1287/mnsc.2019.3297  

   Kadiyala, Bharadwaj; Özer, Özalp; Bensoussan, Alain (October 2019, Management Science)

   This paper studies an inventory management problem faced by an upstream supplier that is in a collaborative agreement, such as vendor-managed inventory (VMI), with a retailer. A VMI partnership provides the supplier an opportunity to manage in- ventory for the supply chain in exchange for point-of-sales (POS)- and inventory-level information from the retailer. However, retailers typically possess superior local market information and as has been the case in recent years, are able to capture and analyze customer purchasing behavior beyond the traditional POS data. Such analyses provide the retailer access to market signals that are otherwise hard to capture using POS information. We show and quantify the implication of the financial obligations of each party in VMI that renders communication of such important market signals as noncredible. To help insti- tute a sound VMI collaboration, we propose learn and screen—a dynamic inventory mechanism—for the supplier to effectively manage inventory and information in the supply chain. The proposed mechanism combines the ability of the supplier to learn about market conditions from POS data (over multiple selling periods) and dynamically de- termine when to screen the retailer and acquire his private demand information. Inventory decisions in the proposed mechanism serve a strategic purpose in addition to their classic role of satisfying customer demand. We show that our proposed dynamic mechanism significantly improves the supplier’s expected profit and increases the efficiency of the overall supply chain operations under a VMI agreement. In addition, we determine the market conditions in which a strategic approach to VMI results in significant profit im- provements for both firms, particularly when the retailer has high market power (i.e., when the supplier highly depends on the retailer) and when the supplier has relatively less knowledge about the end customer/market compared with the retailer. 

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4. Temperature, resources and predation interact to shape phytoplankton size–abundance relationships at a continental scale

   https://doi.org/10.1111/geb.13748  

   Gjoni, Vojsava; Glazier, Douglas S; Wesner, Jeff S; Ibelings, Bastiaan W; Thomas, Mridul K (November 2023, Global Ecology and Biogeography)

   Abstract AimCommunities contain more individuals of small species and fewer individuals of large species. According to the ‘metabolic theory of ecology’, the relationship of log mean abundance with log mean body size across communities should exhibit a slope of −3/4 that is invariant across environmental conditions. Here, we investigate whether this slope is indeed invariant or changes systematically across gradients in temperature, resource availability and predation pressure. Location1048 lakes across the USA. Time Period2012. Major Taxa StudiedPhytoplankton. ResultsWe found that the size–abundance relationship across all sampled phytoplankton communities was significantly lower than −3/4 and near −1 overall. More importantly, we found strong evidence that the environment affects the slope: it varies between −0.33 and −0.93 across interacting gradients of temperature, resource (phosphorus) supply and zooplankton predation pressure. Therefore, phytoplankton communities have orders of magnitude more small or large cells depending on environmental conditions across geographical locations. ConclusionOur results emphasise the importance of the environmental factors' effect on macroecological patterns that arise through physiological and ecological processes. An investigation of the mechanisms underlying the link between individual energetics constrain and macroecological patterns would allow to predict how global warming and changes in nutrients will alter large‐scale ecological patterns in the future. 

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5. Deliberation during online bargaining reveals strategic information

   https://doi.org/10.1073/pnas.2410956122  

   Cotet, Miruna; Zhao, Wenjia_Joyce; Krajbich, Ian (February 2025, Proceedings of the National Academy of Sciences)

   A standard assumption in game theory is that decision-makers have preplanned strategies telling them what actions to take for every contingency. In contrast, nonstrategic decisions often involve an on-the-spot comparison process, with longer response times (RT) for choices between more similarly appealing options. If strategic decisions also exhibit these patterns, then RT might betray private information and alter game theory predictions. Here, we examined bargaining behavior to determine whether RT reveals private information in strategic settings. Using preexisting and experimental data from eBay, we show that both buyers and sellers take hours longer to accept bad offers and to reject good offers. We find nearly identical patterns in the two datasets, indicating a causal effect of offer size on RT. However, this relationship is half as strong for rejections as for acceptances, reducing the amount of useful private information revealed by the sellers. Counter to our predictions, buyers are discouraged by slow rejections—they are less likely to counteroffer to slow sellers. We also show that a drift-diffusion model (DDM), traditionally limited to decisions on the order of seconds, can account for decisions on the order of hours, sometimes days. The DDM reveals that more experienced sellers are less cautious and more inclined to accept offers. In summary, strategic decisions are inconsistent with preplanned strategies. This underscores the need for game theory to incorporate RT as a strategic variable and broadens the applicability of the DDM to slow decisions. 

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