Collective behavior of El Farol attendees

Arthur’s paradigm of the El Farol bar for modeling bounded rationality and inductive behavior is undertaken. The memory horizon available to the agents and the selection criteria they utilize for the prediction algorithm are the two essential variables identified to represent the heterogeneity of agent strategies. The latter is enriched by including various rewarding schemes during decision making. Though the external input of comfort level is not explicitly coded in the algorithm pool, it contributes to each agent’s decision process. Playing with the essential variables, one can maneuver the overall outcome between the comfort level and the endogenously identified limiting state. The distribution of algorithm clusters significantly varies for shorter agent memories. This in turn affects the long-term aggregated dynamics of attendances. We observe that a transition occurs in the attendance distribution at the critical memory horizon where the correlations of the attendance deviations take longer time to decay to zero. A larger part of the crowd becomes more comfortable while the rest of the bar-goers still feel the congestion for long memories. Agents’ confidence on their algorithms and the delayed feedback of attendance data increase the overall collectivity of the system behavior

Revealing instabilities in a generalized triadic supply network: a bifurcation analysis

Supply networks are exposed to instabilities and thus a high level of risk. To mitigate this risk, it is necessary to understand how instabilities are formed in supply networks. In this paper, we focus on instabilities in inventory dynamics that develop due to the topology of the supply network. To be able to capture these topology-induced instabilities, we use a method called generalized modeling, a minimally specified modeling approach adopted from ecology. This method maps the functional dependencies of production rates on the inventory levels of different parts and products, which are imposed by the network topology, to a set of elasticity parameters. We perform a bifurcation analysis to investigate how these elasticities affect the stability. First, we show that dyads and serial supply chains are immune to topology-induced instabilities. In contrast, in a simple triadic network, where a supplier acts as both a first and a second tier supplier, we can identify instabilities that emerge from saddle-node, Hopf, and global homoclinic bifurcations. These bifurcations lead to different types of dynamical behavior, including exponential convergence to and divergence from a steady state, temporary oscillations around a steady state, and co-existence of different types of dynamics, depending on initial conditions. Finally, we discuss managerial implications of the results

Türkiye’de bulunan yoğun bakımlarda sabun, kağıt havlu ve alkol bazlı el dezenfektanı yeterli mi?: Phokai çalışması sonuçları

Introduction: Hand hygiene is one of the most effective infection control measures to prevent the spread of healthcare-associated infections (HCAI). Water, soap, paper towel and hand disinfectant must be available and adequate in terms of effective hand hygiene. The adequacy of hand hygiene products or keeping water-soap and paper towel is still a problem for many developing countries like Turkey. In this multicenter study, we analyzed the adequacy in number and availability of hand hygiene products.Materials and Methods: This study was performed in all intensive care units (ICUs) of 41 hospitals (27 tertiary-care educational, 10 state and four private hospitals) from 22 cities located in seven geographical regions of Turkey. We analyzed water, soap, paper towel and alcohol-based hand disinfectant adequacy on four different days, two of which were in summer during the vacation time (August, 27th and 31st 2016) and two in autumn (October, 12th and 15th 2016).Results: The total number of ICUs and intensive care beds in 41 participating centers were 214 and 2357, respectively. Overall, there was no soap in 3-11% of sinks and no paper towel in 10-18% of sinks while there was no alcohol-based hand disinfectant in 1-4.7% of hand disinfectant units on the observation days. When we compared the number of sinks with soap and/or paper towel on weekdays vs. weekends, there was no significant difference in summer. However, on autumn weekdays, the number of sinks with soap and paper towel was significantly lower on weekend days (p<0.0001, p<0.0001) while the number of hand disinfectant units with alcohol-based disinfectant was significantly higher (p<0.0001).Conclusion: There should be adequate and accessible hand hygiene materials for effective hand hygiene. In this study, we found that soap and paper towels were inadequate on the observation days in 3-11% and 10-18% of units, respectively. Attention should be paid on soap and paper towel supply at weekends as well

Mapping the Supply Chain: Why, What and How?

There is now widespread appreciation of the critical role played by supply chains in the global economy. Supply chains are dominant concerns for many organisations, governments, policy makers, and consumers. A primary requirement in addressing many of the contemporary supply challenges is the need to 'map' a supply system. With notable exceptions, much of our supply chain management literature has shied away from providing guidance on the mapping process. In this paper, we stress the reasons for the increased emphasis on mapping. We review the academic literature, highlighting the diversity of mapping exercises conducted by researchers and the lack of clarity about different types of maps developed. Supply chain mapping has been used as an umbrella term for studies at very different aggregation levels. We define the most fundamental elements needed to create a supply chain map and develop a formal hierarchy of supply systems for mapping at different levels of analysis. The hierarchy provides a structured way to consider the diversity of mapping exercises in the literature and helps to define the unit of analysis for a mapping study. We illustrate the hierarchy with a range of examples from the textile and apparel industry. We identify the primary and secondary data sources that underpin mapping studies, highlighting the significant challenges in using them. We discuss the emerging commercial solutions to capture, map, and analyse supply systems for different purposes. In an increasingly data rich world, there are many opportunities to develop the supply chain mapping process further

Influence of Media and Temperature on the Growth and the Biological Activities of Desmodesmus protuberans (FE Fritsch & MF Rich) E. Hegewald

WOS: 000432895600006The aim of this study is to determine different culture media and temperature values on the growth rate of Desmodesmus protuberans (F.E. Fritsch & M.F.Rich) E. Hegewald, and to investigate antimicrobial and antioxidant potency of the crude extracts. The microalga isolates from Egirdir Lake in Isparta (Turkey) was identified as D. protuberans and included in Ege University Microalgae Culture Collection. D. protuberans was cultivated at two temperature regimes (22 and 28 degrees C) and growth media (BBM, BG-11 and RD medium) under the light intensity of 75 mu mol m(-2) S-1 for testing the impact of different environmental conditions on the growth rate. All of the productions of D. protuberans biomass were extracted with methanol and investigated the antimicrobial and antioxidant activity. Antimicrobial activities of the extracts of alga were tested by disc diffusion assay against five Gram-positive and four Gram-negative bacterial strains and against the yeast Candida albicans. The methanol extract of the biomass from BBM medium (28 degrees C) showed the highest growth inhibition effect on C. albicans, while RD medium (22 degrees C) extract showed the highest antioxidant activity. These results demonstrated that the differences in the bioactivity of biomasses are stemmed from different temperature and media conditions

Can “Ugly Veg” Supply Chains Reduce Food Loss?

The tradition of marketing only aesthetically agreeable produce by retailers contributes to a major source of food loss through “ugly veg”, i.e., the produce that does not look “regular”. In this paper, we examine the relations between different tiers of agri-food supply chains to study the impact of marketing ugly veg on different supply chain members and the food loss in the system. We examine and compare scenarios of a centralized supply chain, a traditional supply chain without ugly veg, an ugly veg supply chain with a single retailer offering both regular produce and ugly veg, and a two-retailer supply chain where an auxiliary retailer sells the ugly veg. We characterize the equilibrium decisions in these systems and also provide analytical results and insights on the effectiveness of different supply chain designs based on a comprehensive numerical study. We demonstrate the conditions under which the supply chain can reduce overall food loss. For sufficiently high cost of effort, selling ugly veg through the single retailer reduces food loss. Nonetheless, the grower is generally better off offering the ugly veg to an auxiliary retailer. We show that the ratio of food loss per cultivated land always decreases in the two-retailer supply chain, while the total food loss might increase for sufficiently high cost of effort