The space-air-ground integrated network (SAGIN) is considered to be a significant framework for realizing the vision of "6G intelligent connection of all things." A typical SAGIN consists of three ...parts: a space-based network composed of various orbiting satellites, an air-based network composed of aircraft, and a traditional ground-based network. Considering the cost of satellite launch, the network needs to be flexible and controllable. In order to ensure that the ground can handle satellite anomalies in real time by program, it is necessary to introduce in-orbit programmable networks, such as the software-defined network (SDN). In the network management architecture, if the controller plane in the SDN adopts the flat management scheme, the expansion of the control plane is limited due to the low efficiency of data synchronization among controllers. Compared with controller deployments on terrestrial networks, multicontroller deployments in the SAGIN face the following problems: the dynamic change of the satellite network topology, the large-scale network nodes, the increase or decrease in the number of aerial vehicles, and the unbalanced distribution of ground users. Therefore, it is of great significance to study how to optimize the deployment of multiple controllers in the SDN-enabled SAGIN. This article introduces an SDN into the SAGIN and designs a hierarchical domain-based SDN-enabled SAGIN architecture. A multicontroller deployment strategy for the hierarchical domain-based SDN-enabled SAGIN is proposed. First, we divide the SDN control plane into two layers, i.e., the primary controller layer is deployed on the ground network and the secondary on the space-based network. The SDN data plane is composed of space-based, air-based, and ground-based networks. Second, considering the average network delay and the controller load, a multiobjective optimization model is constructed. To determine the number of controllers and the relative positions of switch nodes and controllers, the clustering algorithm based on k -means is adopted to initially divide the data plane. Finally, to improve the global search ability of the algorithm, a multiobjective optimization algorithm based on a genetic algorithm is adopted. The simulation results show that the proposed strategy is effective in reducing the average network delay and improving the controller load balance. Compared to other algorithms, the average network delay is reduced by 13.3% and the controller load is improved by 10.33%.
Many companies are under pressure to improve pay transparency; however, its impact on their agents and principals remains unclear. As a way to investigate the upside and downside of pay transparency, ...we conduct our study based on a scenario in which agents have “cognitive bias” (namely, over‐ or underconfident). We also capture the notion of “social comparisons” behavior (namely, behind‐averse and ahead‐seeking) that occurs under pay transparency. By exploring a one‐principal‐two‐agent model, we find that agents' optimal effort decisions are affected by the “intersection” between agents' social comparison behavior and cognitive bias. Specifically, relative to the opaque policy, we find that pay transparency can entice agents to improve their job performance (in general). Our analysis also provides a guideline for principals to implement transparent payment policies properly (including the optimal payment scheme and the recruitment strategy). Specifically, pay transparency could enable the principal to offer a lower merit‐based factor level but a higher base salary level than opaque policy to motivate agents. To obtain high retained earnings, it is profitable for the principal to hire an overconfident agent if the principal chooses to adopt the opaque policy, but hire a mildly underconfident agent if pay transparency is selected. Moreover, we extend the base model to incorporate working capability heterogeneity across agents. We find that the agent's effort incentive and his opponent's working capability move in the same direction when the two agents' working capabilities are comparable under the transparent policy. Finally, by incorporating the environment's relative favoritism into the base model, we observe that when the environment is highly uncertain, the underconfident agent is willing to leverage environment uncertainty but the overconfident agent is willing to exert more effort.
We examine a (large) manufacturer’s bribery decision (to bribe or not to bribe) arising from a procurement auction under “disparate corruption pressure” when another (small) manufacturer is known to ...offer the auctioneer (i.e., the intermediary) a bribe in exchange for the “right of first refusal.” We discover that the large manufacturer should refuse to pay bribes at all times in order to prevent from leaking its private cost information to the small manufacturer and prevent from intensifying the competition. However, even when the large manufacturer is disadvantaged for refusing to bribe, we show that it can benefit from this corrupted auction when the difference in production efficiency or the bribe is high so that the “positive force” (i.e., cost advantage) derived from the right of first refusal dominates the information disadvantage. Hence, under a specific condition, the large manufacturer has no incentive to expose the collusion between the intermediary and the corrupt manufacturer. Such a “silence tactic” provides a plausible explanation for the prevalence of corrupt auctions in practice.
Objectives
Because radiotherapy is indispensible for treating cervical cancer, it is critical to accurately and efficiently delineate the radiation targets. We evaluated a deep learning (DL)‐based ...auto‐segmentation algorithm for automatic contouring of clinical target volumes (CTVs) in cervical cancers.
Methods
Computed tomography (CT) datasets from 535 cervical cancers treated with definitive or postoperative radiotherapy were collected. A DL tool based on VB‐Net was developed to delineate CTVs of the pelvic lymph drainage area (dCTV1) and parametrial area (dCTV2) in the definitive radiotherapy group. The training/validation/test number is 157/20/23. CTV of the pelvic lymph drainage area (pCTV1) was delineated in the postoperative radiotherapy group. The training/validation/test number is 272/30/33. Dice similarity coefficient (DSC), mean surface distance (MSD), and Hausdorff distance (HD) were used to evaluate the contouring accuracy. Contouring times were recorded for efficiency comparison.
Results
The mean DSC, MSD, and HD values for our DL‐based tool were 0.88/1.32 mm/21.60 mm for dCTV1, 0.70/2.42 mm/22.44 mm for dCTV2, and 0.86/1.15 mm/20.78 mm for pCTV1. Only minor modifications were needed for 63.5% of auto‐segmentations to meet the clinical requirements. The contouring accuracy of the DL‐based tool was comparable to that of senior radiation oncologists and was superior to that of junior/intermediate radiation oncologists. Additionally, DL assistance improved the performance of junior radiation oncologists for dCTV2 and pCTV1 contouring (mean DSC increases: 0.20 for dCTV2, 0.03 for pCTV1; mean contouring time decrease: 9.8 min for dCTV2, 28.9 min for pCTV1).
Conclusions
DL‐based auto‐segmentation improves CTV contouring accuracy, reduces contouring time, and improves clinical efficiency for treating cervical cancer.
The recent literature argues that offering consumer returns, such as money‐back guarantees (MBGs), reduces quality differentiation in competitive markets. We show that this argument does not hold in ...general. We propose a new certainty‐equivalent approach, which shows that offering product returns only changes the two firms' marginal costs without affecting their quality differentiation. Our proposed approach directly reveals that asymmetry of salvage values may overturn the recent finding that MBGs help the low‐quality firm. Since MBGs only lead to marginal cost reductions, we show that each firm should adopt MBGs in equilibrium irrespective of the competitor's choice. We then examine the role of offering consumer returns in determining the firms' competitive product strategies. We demonstrate that offering MBGs does not directly affect the quality differentiation choices, and discuss the impacts of production technology and consumer valuation.
Abstract Personal protective equipment (PPE) like face mask is important in managing pandemic. Typically, there exist different standards for face masks such as N95 and KN95. In response to the ...supply shortages of N95 mask in 2020, KN95 mask was allowed to be sold in U.S. to substitute the standard product N95. This paper considers when suppliers make products to supply both domestic and overseas markets with different product standards (i.e., the standard product for domestic/overseas market is the ordinary/high‐type product), and explore the impact of the substitution policy of allowing the ordinary product as a substitutable product in the overseas market. Analytically we prove that this substitution policy is win‐win by increasing the sales in both markets when ordinary and high‐type products are close substitutes in the presence of strong diseconomies of scale in material supply, or the high‐type product has a dominant competitive advantage in the presence of strong economies of scale in material supply. By contrast, the substitution policy is lose‐lose by decreasing the sales in both markets when the competitive advantage of the high‐type product is small in the presence of strong economies of scale in material supply. Moreover, numerical studies with the real data show the robustness of our analytical findings, and unfold the backfire of imposing export restriction on the standard product for domestic market.
We construct a supply chain to investigate the reason why it is uncommon for the traditional retailer to function as the pre-warehouse of the online retailer. The product only offered by the ...traditional retailer is labelled as the differentiated product, while the product supplied by both the traditional retailer and the third-party suppliers is called the common product. As the online retailer' common product competes directly with the differentiated product, whether the traditional retailer should supply the common product becomes sophisticated. In this paper, we identify an intrinsic rationale for the traditional retailer not to supply the common product, even if he is unambiguously cost advantageous vis-a-vis the third-party suppliers. This is because the online retailer's order serves as a commitment device that puts the traditional retailer at the disadvantageous follower's position in the differentiated and common products competition; moreover, this quantity commitment allows the online retailer to clinch a better bargaining position on the differentiated product. We further show that it never pays the online retailer to split orders between the traditional retailer and the third-party suppliers. Our results are robust against the traditional retailer's capacity constraint, consumers' preference over differentiated and common products, and supply chain contractual form.
The reservation of goods to be produced in the micro, small, and medium enterprises (MSME) sector, in the early years after India's independence, addressed the dual needs of development of the ...industrial sector and production of goods. However, these industrial policies created an incentive for firms to remain small so that they can continue to avail of the benefits provided by the Government. On the positive side, the MSMEs typically employ more labor intensive production processes and consequently contribute significantly to the provision of employment opportunities, generation of income, and poverty reduction. But, on the negative side, the policies have also partly facilitated the creation of a divide in terms of productivity between the MSMEs and large sized firms. In particular the policy raises important questions for a firm auctioning supply contracts among suppliers with a significant cost differential. In this paper we propose an idea to allocate supply contracts wherein a manufacturing firm partitions the stochastic demand into mutually exclusive portions and awards each portion to a different supplier. We characterize such an optimal procurement mechanism when there are two types of suppliers and an arbitrary number of demand portions. We show that the optimal procurement may require the manufacturer to intentionally withhold some demand portion, and this arises when one type of supplier is considerably inefficient in serving a demand portion. We extend our analysis to the cases with multiple types with two suppliers and two types with multiple suppliers. The optimal partition is composed of at most six contiguous demand portions, and it may include a detrimental demand portion that only generates a negative expected payoff to both supplier types. Our demand partitioning mechanism leads to a strictly higher manufacturer's expected payoff than the conventional winner‐take‐all case unless one supplier type completely dominates the other. We present numerical experiments that indicate when such a mechanism holds the greatest advantage for the buyer.
We consider a network model where individuals exert efforts in two types of activities that are interdependent. These activities can be either substitutes or complements. We provide a full ...characterization of the Nash equilibrium of this game for any network structure. We show, in particular, that quadratic games with linear best-reply functions aggregate nicely to multiple activities because equilibrium efforts obey similar formulas to that of the one-activity case. We then derive some comparative-statics results showing how own productivity affects equilibrium efforts and how network density impacts equilibrium outcomes.
Erinacine A-enriched Hericium erinaceus mycelia is a well-established potential therapeutic agent for neurodegenerative disorders. However, the effect of erinacine A-enriched H. erinaceus mycelia on ...promoting longevity remains unclear. This is the first study to investigate the effect of erinacine A-enriched H. erinaceus mycelia on lifespan-prolonging activity in Drosophila melanogaster and senescence-accelerated P8 (SAMP8) mice. Two hundred D. melanogaster and 80 SAMP8 mice of both sexes were randomly divided into four groups and were administered with either the standard, low-dose, mid-dose, or high-dose erinacine A-enriched H. erinaceus mycelia. After treatment, the lifespan was measured in D. melanogaster, and the lifespan, food intake and oxidative damage were evaluated in SAMP8 mice. Results showed that supplementation with erinacine A-enriched H. erinaceus mycelia extended the lifespan in both D. melanogaster and SAMP8 by a maximum of 32% and 23%, respectively, compared to the untreated controls. Moreover, erinacine A-enriched H. erinaceus mycelia decreased TBARS levels and induced the anti-oxidative enzyme activities of superoxide dismutase, catalase, and glutathione peroxidase. Together, these findings suggest that erinacine A-enriched H. erinaceus mycelia supplement could promote longevity, mediated partly through the induction of endogenous antioxidants enzymes.
PDF
