Conformal Navigation Transformations with Application to Robot Navigation in Complex Workspaces

Navigation functions provide both path and motion planning, which can be used to ensure obstacle avoidance and convergence in the sphere world. When dealing with complex and realistic scenarios, constructing a transformation to the sphere world is essential and, at the same time, challenging. This work proposes a novel transformation termed the conformal navigation transformation to achieve collision-free navigation of a robot in a workspace populated with obstacles of arbitrary shapes. The properties of the conformal navigation transformation, including uniqueness, invariance of navigation properties, and no angular deformation, are investigated, which contribute to the solution of the robot navigation problem in complex environments. Based on navigation functions and the proposed transformation, feedback controllers are derived for the automatic guidance and motion control of kinematic and dynamic mobile robots. Moreover, an iterative method is proposed to construct the conformal navigation transformation in a multiply-connected workspace, which transforms the multiply-connected problem into multiple simply-connected problems to achieve fast convergence. In addition to the analytic guarantees, simulation studies verify the effectiveness of the proposed methodology in workspaces with non-trivial obstacles

The causal relationship between gut microbiota and leukemia: a two-sample Mendelian randomization study

BackgroundThe association between gut microbiota and leukemia has been established, but the causal relationship between the two remains unclear.MethodsA bidirectional two-sample Mendelian randomization (MR) was used to analyze the causal relationship between gut microbiota and leukemia. Microbiome data (n = 14,306) and leukemia (n = 1,145) data were both sourced from European populations. Single nucleotide polymorphisms (SNPs) were selected as instrumental variables based on several criteria. We employed various MR methods, such as the inverse variance weighted (IVW) method, to evaluate the causal effect between exposure and outcomes and conducted sensitivity analyses to validate the heterogeneity and pleiotropy of the instrumental variables.Results5,742 qualified instrumental variables were included. In the primary MR results, a total of 10 gut microbial taxa were associated with leukemia risk. Genus Blautia and genus Lactococcus are risk factors for acute lymphoblastic leukemia [genus Blautia odds ratio (OR): 1.643, 95% confidence interval (CI): 1.592 ~ 1.695, Adjusted p < 0.001; genus Lactococcus OR: 2.152, 95% CI: 1.447 ~ 3.199, Adjusted p = 0.011]. Genus Rikenellaceae RC9 gut group, genus Anaerostipes, genus Slackia, and genus Lachnospiraceae ND3007 group are risk factors for acute myeloid leukemia [genus Rikenellaceae RC9 gut group OR: 1.964, 95% CI: 1.573 ~ 2.453, Adjusted p < 0.001; genus Anaerostipes OR: 2.515, 95% CI: 1.503 ~ 4.209, Adjusted p = 0.017; genus Slackia OR: 2.553, 95% CI: 1.481 ~ 4.401, Adjusted p = 0.022; genus Lachnospiraceae ND3007 group OR: 3.417, 95% CI: 1.960 ~ 5.959, Adjusted p = 0.001]. Genus Ruminococcaceae UCG011 and genus Ruminococcaceae UCG014 were risk factors for chronic myeloid leukemia (genus Ruminococcaceae UCG011 OR: 2.010, 95% CI: 1.363 ~ 2.963, Adjusted p = 0.044; genus Ruminococcaceae UCG014 OR: 3.101, 95% CI: 1.626 ~ 5.915, Adjusted p = 0.044). Genus Slackia was a protective factor for acute lymphoblastic leukemia (genus Slackia OR: 0.166, 95% CI: 0.062 ~ 0.443, Adjusted p = 0.017). Family Acidaminococcaceae was a protective factor for acute myeloid leukemia (family Acidaminococcaceae OR: 0.208, 95% CI: 0.120 ~ 0.361, Adjusted p < 0.001). Genus Desulfovibrio was a protective factor for chronic lymphoblastic leukemia (genus Desulfovibrio OR: 0.581, 95% CI: 0.440 ~ 0.768, Adjusted p = 0.020). Sensitivity analysis revealed no heterogeneity or pleiotropy between SNPs.ConclusionThis study revealed the causal relationship between the gut microbiota and leukemia, and identified potential pathogenic bacteria and probiotic taxa associated with the onset of leukemia. This research may aid in the early detection of various types of leukemia and offer a new direction for the prevention and treatment of leukemia

External financing, channel power structure and product green R&D decisions in supply chains

Purpose – This study aims to focus on the optimal green R&D of a capital-constrained supply chain under different channel power structures as well as the impact of capital constraint, financing cost, channel power structure and cost-reducing efficiency on green R&D and supply chain profitability. Design/methodology/approach – A two-echelon supply chain is considered. The upstream firm engages in green R&D but has capital constraints that can be overcome by external financing. Green R&D is beneficial to reduce production costs and increase consumer demand. Based on whether or not the upstream firm is capital constrained and dominates the supply chain, four models are developed. Findings – Capital constraints significantly lower green R&D and supply chain profitability. Transferring leadership from the upstream to the downstream firms leads to higher green R&D levels and downstream firm profitability, whereas the upstream firm's profitability is increased (decreased) if green R&D investment efficiency is high (low) enough. Greater financing costs reduce green R&D and downstream firm profitability; however, the upstream firm's profitability under the model in which it functions as the follower increases if the initial capital is sufficient. More importantly, empirical analysis based on practice data is used to verify the theoretical results reported above. Practical implications – This study reveals how upstream firms in supply chains decide green R&D decisions in situations with capital constraints, providing managers and governments with an understanding of the impact of capital constraint, channel power structure, financing cost and cost-reducing efficiency on supply chain green R&D and profitability. Originality/value – The major contributions are the exploration of supply chain green R&D by taking into consideration channel power structures and cost-reducing efficiency and the validation of theoretical results using practice data

An improved positioning algorithm in a long-range asymmetric perimeter security system

In this paper, an improved positioning algorithm is proposed for a long-range asymmetric perimeter security system. This algorithm employs zero-crossing rate to detect the disturbance starting point, and then utilizes an improved empirical mode decomposition to obtain the effective time-frequency distribution of the extracted signal. In the end, a cross-correlation is used to estimate the time delay of the effective extracted signal. The scheme is also verified and analyzed experimentally. The field test results demonstrate that the proposed scheme can achieve a detection of 96.60% of positioning errors distributed within the range of 0-±20 m at the sensing length of 75 km, which significantly improves the positioning accuracy for the long-range asymmetric fence perimeter application

Immune-modulation by polyclonal IgM treatment reduces atherosclerosis in hypercholesterolemic apoE−/− mice

AbstractObjectiveGamma-globulin treatment reduces experimental atherosclerosis by modulating immune function; however the effect of IgM on atherosclerosis is not known. We investigated the effect of serum-derived, non-immune polyclonal IgM (Poly-IgM) on atherosclerosis in mice with advanced disease and also assessed its immune-modulatory effects.Methods and resultsAortic atherosclerosis was assessed in apoE−/− mice fed atherogenic diet starting at 6 weeks of age. In addition, mice were also subjected to perivascular cuff injury to the carotid artery at 25 weeks of age to induce accelerated atherosclerosis. At the time of injury, the mice were treated weekly with a commercially available Poly-IgM (0.4mg/mouse) or PBS for 4 weeks and euthanized at 29 weeks of age. Poly-IgM reduced aortic atherosclerosis, and reduced lesion size in the aortic sinus and injured carotid artery, without significant changes in serum cholesterol levels. Poly-IgM treatment was associated with increased anti-oxLDL IgG titers and a reduction in the % splenic CD4+ T cells compared to controls. The splenic CD4+ T cell cultured from the Poly-IgM treated mice had reduced proliferation in vitro compared with controls.ConclusionPoly-IgM treatment reduced aortic and accelerated carotid atherosclerosis in apoE−/− mice in association with increased anti-oxLDL IgG titers, and reduced number and proliferative function of splenic CD4+ T cells. Our study identifies a novel athero-protective and immunomodulatory role for non-immune polyclonal IgM

CD8+ T Cells Mediate the Athero-Protective Effect of Immunization with an ApoB-100 Peptide

Immunization of hypercholesterolemic mice with selected apoB-100 peptide antigens reduces atherosclerosis but the precise immune mediators of athero-protection remain unclear. In this study we show that immunization of apoE (-/-) mice with p210, a 20 amino acid apoB-100 related peptide, reduced aortic atherosclerosis compared with PBS or adjuvant/carrier controls. Immunization with p210 activated CD8+ T cells, reduced dendritic cells (DC) at the site of immunization and within the plaque with an associated reduction in plaque macrophage immunoreactivity. Adoptive transfer of CD8+ T cells from p210 immunized mice recapitulated the athero-protective effect of p210 immunization in naïve, non-immunized mice. CD8+ T cells from p210 immunized mice developed a preferentially higher cytolytic response against p210-loaded dendritic cells in vitro. Although p210 immunization profoundly modulated DCs and cellular immune responses, it did not alter the efficacy of subsequent T cell dependent or independent immune response to other irrelevant antigens. Our data define, for the first time, a role for CD8+ T cells in mediating the athero-protective effects of apoB-100 related peptide immunization in apoE (-/-) mice

Impacts of put option contract and supply chain structure in a multi-period supply chain with uncertain demand

This paper builds the multi-period optimization models that incorporate put option contract and two supply chain structures to determine the production decision for a supplier and the ordering decision for a manufacturer in a two-stage supply chain. This paper applies the method of dynamic programming to derive the structures of optimal policies and provides an approximate algorithm to evaluate the myopic policies. This paper also conducts numerical examples to illustrate the impacts of put option contract, supply chain structure and demand risk on the members’ decisions and total profits as well as the channel’s total profit. The results indicate that put option contract can motivate to increase the channel’s service level and reduce the manufacturer’s inventory risk under two supply chain structures, when compared to the case without put option contract. In the manufacturer-led structure, the channel always benefits from put option contract, the supplier benefits from put option contract with a high option price and a low exercise price, while the manufacturer benefits from put option contract with a low option price and a high exercise price. In the supplier-led structure, the channel and the manufacturer always benefit from put option contract, while the supplier benefits from put option contract with a high option price and a low exercise price. With put option contract, the supplier is more profitable in the manufacturer-led structure than in the supplier-led structure, while the manufacturer and the channel are more profitable in the supplier-led structure than in the manufacturer-led structure. Without and with put option contract, the optimal total profits of two members and the channel will first decrease and then increase in the demand risk. Finally, this paper identifies the explicit conditions under which the multi-period supply chain can be coordinated via put option contract under two supply chain structures. With a coordinating contract, the supplier and the manufacturer are better off compared to the case without put option contract

Empirical Research on China’s Carbon Productivity Decomposition Model Based on Multi-Dimensional Factors

Based on the international community’s analysis of the present CO2 emissions situation, a Log Mean Divisia Index (LMDI) decomposition model is proposed in this paper, aiming to reflect the decomposition of carbon productivity. The model is designed by analyzing the factors that affect carbon productivity. China’s contribution to carbon productivity is analyzed from the dimensions of influencing factors, regional structure and industrial structure. It comes to the conclusions that: (a) economic output, the provincial carbon productivity and energy structure are the most influential factors, which are consistent with China’s current actual policy; (b) the distribution patterns of economic output, carbon productivity and energy structure in different regions have nothing to do with the Chinese traditional sense of the regional economic development patterns; (c) considering the regional protectionism, regional actual situation need to be considered at the same time; (d) in the study of the industrial structure, the contribution value of industry is the most prominent factor for China’s carbon productivity, while the industrial restructuring has not been done well enough

Quality and price competition in a duopoly under product liability and traceability

This study aims to explore how traceability affects quality and price competition in a duopoly. A theoretical model is developed in which both enterprises are liable to recall low-quality (defective) products identified by traceability and compensate consumers for the disutility caused by unidentified low-quality products. The equilibrium results are derived by determining the optimal product quality and sales price decisions. The key findings are highlighted below. (1) Traceability affects product quality primarily through the expected social cost (the sum of expected recall cost and expected consumer disutility), i.e., higher (lower) expected social cost induced by increased traceability of each enterprise leads to higher (lower) product quality for both enterprises, enhancing (reducing) quality competition. (2) If an enterprise’s improved (decreased) product quality is driven by its own increased traceability, it will result in lower (higher) consumer demand and profit, while it will result in higher (lower) consumer demand and profit if caused by its competitor’s increased traceability. (3) If an enterprise’s increased traceability results in higher expected social cost, the enterprise’s sales price falls while the competitor’s sales price rises; otherwise, both enterprises’ sales prices fall, leading to greater price competition. (4) Quality competition is unaffected by product liability but is improved by increased recall cost and consumer disutility, whereas price competition is intensified by increased consumer disutility but is reduced by increased product liability and recall cost. Managerial insights are also discussed