Research on EPQ Model Based on Random Defective Rate

In the real economic life, it is inevitable that a lot of phenomena will happen, such as damage in transportation and machine failure, which may generate a certain percentage of defective products in the process of logistics and production. Especially in the production process, the stoppage on the production line often brings about defective products. To provide mathematical models that more closely conform to actual inventories and respond to the factors that contribute to inventory costs, based on the classical EPQ model, this paper develops an EPQ model for defective items with a certain price relative to the defective level. And this paper also considers the issue that defective items are sold at a lower price which depends on the degree of product defects. A mathematical model is developed and numerical examples are provided to illustrate the solution procedure. The research will enrich researches and it has important practical significance

Pricing and Return Policies in a Competitive Market: A Consumer-Valuation Based Analysis with Valuation Uncertainties

In this study, we develop a series of consumer-valuation-based models to investigate the pricing and return policies of the sellers in a competitive e-commerce market. Differing from the competition models in literature, a novel two-dimensional valuation structure is built, which considers the valuations of a consumer on two products and the valuation differentiation of all consumers on each product. We consider both monopoly and duopoly (competitive) markets. In each market, two models are respectively developed, one with and one without the return policies. We derive the solutions for the four models, and conduct some analytical and numerical investigations. The results show that return policy with a partial refund is always chosen by the sellers in both monopoly and duopoly markets. Return policy benefits the seller in a monopoly market, but may not benefit the sellers in a duopoly market. In the duopoly models, one seller can be considered as a monopoly seller who meets a new competitor. Our results show that the monopoly seller will reduce its price by no more than 20% when there comes a competitor, and, counter-intuitively, it will meanwhile adopt a severer return policy to the consumers

Emergency-Dependent Supply Decisions with Risk Perception and Price Control

This paper studies the impact of emergencies on the supplier’s decision-making behaviors including production and information sharing in consideration of consumer risk perception, consumer loss aversion phenomenon, and government price control. The intensity of emergencies is sequential and emergencies can be divided into two types (positive or negative) according to their effect on demand. When emergencies have negative effect on demand, the supplier’s sales will reduce and he would share information to the market. When emergencies have positive effect on demand, we find that when the price is under price cap the supplier will not share information to the market; when the price reaches price cap, the supplier will share a certain amount of information to the market. We were surprised to find that increasing demand is not always good for the supplier when there exist government price control and lost sales penalty, and information helps the supplier to effectively manipulate demand

Construction of a competency index system for shift nurses in China: A Delphi study

Abstract Aim This study developed a set of competency evaluation indicators for shift work nurses in China. Background Nurses on night shifts must deal with the treatment, nursing, and management work, which requires excellent competency of night shift nurses in their knowledge, skills, and ability. However, the competency evaluation index system for shift work nurses has not been established yet in China. Methods This study performed a literature review and semi‐structured interviews to draft the preliminary competency evaluation indicators for nursing shift work. The Delphi technique was adopted to administer two rounds of questionnaires on 21 nursing experts. Results The positive coefficients of experts in the two rounds were 100% and 90.48%, respectively, whereas the authority coefficients were 0.974 and 0.971, respectively. The coefficients of variation were 0.00–0.26 and 0.00–0.16, respectively. The competency evaluation index system for shift work nurses consisted of 2 first‐level indicators, 16 second‐level indicators, and 67 third‐level indicators. Conclusion The competency index system of shift work nurses is scientific and applicable. Implications for Nursing Management The competency evaluation index system of shift work nurses would provide an effective practical framework for shift nursing administration to evaluate, train, and assess the competency of shift work nurses

The singularity of the partially coherent beam in biological tissue

The singularity of the partially coherent beam propagating in biological tissue has been demonstrated, mainly including the properties of the normalized intensity distribution and phase evolution. It is shown that as the propagation distance increases, the evolution of the normalized intensity distribution undergoes several different stages, as well as the transformation of phase singularities takes place. Especially, the effect of the topological charge, the radial index, beam wave length and spatial coherence length on the beam singularity is analyzed, respectively

Spatiotemporal Variation in the Land Use/Cover of Alluvial Fans in Lhasa River Basin, Qinghai–Tibet Plateau

Alluvial fans are an important land resource with agricultural potential in Qinghai–Tibet Plateau. The spatiotemporal variation in land use/cover is an important indicator to understand the value of alluvial fans and protect and make scientific use of such fans. In this study, the spatiotemporal characteristics of land use/cover are determined by analysing the land use/cover changes of alluvial fans in the Lhasa River Basin (LRB) at different times, counties/districts, altitudes, and gradients. Results show that the area of cultivated land and the artificial land provided by alluvial fans for LRB has continuously increased. In 2000, 2010, and 2020, 17.72%, 21.84%, and 24.17% of cultivated land and 7.89%, 7.51%, and 25.24% of artificial land in LRB were provided by alluvial fans, respectively. At all altitudes and slopes, cultivated land and artificial land are increasing but the increasing part is basically due to the massive loss of grassland. The spatiotemporal changes in all land use/cover types of alluvial fans were dominated by human activities, although they were also influenced by natural factors to some degree

Viral control of biomass and diversity of bacterioplankton in the deep sea

International audienceViral abundance in deep-sea environments is high. However, the biological, ecological andbiogeochemical roles of viruses in the deep sea are under debate. In the present study,microcosm incubations of deep-sea bacterioplankton (2,000 m deep) with normal andreduced pressure of viral lysis were conducted in the western Pacific Ocean. We observed anegative effect of viruses on prokaryotic abundance, indicating the top-down control ofbacterioplankton by virioplankton in the deep-sea. The decreased bacterial diversity and a different bacterial community structure with diluted viruses indicate that viruses are sus-taining a diverse microbial community in deep-sea environments. Network analysis showedthat relieving viral pressure decreased the complexity and clustering coefficients butincreased the proportion of positive correlations for the potentially active bacterial com-munity, which suggests that viruses impact deep-sea bacterioplankton interactions. Ourstudy provides experimental evidences of the crucial role of viruses in microbial ecology and biogeochemistry in deep-sea ecosystems

Two Secretory T2 RNases Act as Cytotoxic Factors Contributing to the Virulence of an Insect Fungal Pathogen

RNase T2 members are secreted by several pathogens or parasites during infection, playing various roles in pathogen–host interaction. However, functions of those members in biocontrol microbes targeting their hosts are still unknown. Here, we report that an insect fungal pathogen, Beauveria bassiana, produces two secretory RNase T2 members that act as cytotoxic factors, which were examined by insect bioassays using the targeted gene(s) disruption and overexpression strains. Overexpression strains displayed dramatically increased virulence, which was concurrent with few fungal cells and hemocytes in hemocoel, suggesting a cytotoxicity of the overexpressed gene products. In vitro assays using yeast-expressed proteins verified the cytotoxicity of the two members against insect cells, to which the cytotoxic effect was dependent on their RNases enzyme activities and glycosylation modification. Moreover, the excessive humoral immune responses triggered by the two ribonucleases were examined. These results suggested prospects of these two T2 ribonucleases for improvement of biocontrol agents