Accurate and systematic transcriptome-wide detection of 5-methylcytosine (m
C) has proved challenging, and there are conflicting views about the prevalence of this modification in mRNAs. Here we ...report an experimental and computational framework that robustly identified mRNA m
C sites and determined sequence motifs and structural features associated with the modification using a set of high-confidence sites. We developed a quantitative atlas of RNA m
C sites in human and mouse tissues based on our framework. In a given tissue, we typically identified several hundred exonic m
C sites. About 62-70% of the sites had low methylation levels (<20% methylation), while 8-10% of the sites were moderately or highly methylated (>40% methylation). Cross-species analysis revealed that species, rather than tissue type, was the primary determinant of methylation levels, indicating strong cis-directed regulation of RNA methylation. Combined, these data provide a valuable resource for identifying the regulation and functions of RNA methylation.
While the previous literature overlooks value-added service in a closed-loop supply chain (CLSC), we consider new research problems with embedding value-added service into remanufacturing models. In ...this paper, we mainly study the role of value-added service in a CLSC and investigate how the value-added service influences profits and other decision variables. Then, we evaluate the performance of the CLSC in different service structures, where a manufacturer or a retailer provide the value-added service. Systematic comparisons and numerical studies show that the supply chain is more effective when service is provided by a manufacturer rather than by a retailer. Also, value-added service improves the whole supply chain performance and plays a regulatory role in a CLSC and influences the decisions of supply chain members. We also show that while a service cost-sharing mechanism can only optimise rather than achieve the supply chain coordination, and the degree of optimisation depends on cost-sharing percentage, the two-part tariff contract can be an effective mechanism to coordinate decentralised service scenarios by generating the same supply chain performance in a centralised service architecture model.
Green manufacturers are faced with decision problems whether to acquire the quality information from third-party assessment agencies and to disclose the quality information to other supply chain ...members. While the existing research of closed-loop supply chain (CLSC) has not considered the voluntary and mandatory information disclosure, this study considers the quality information disclosure strategies of a green manufacturer after acquiring the quality information in the closed-loop supply chain. (1) The study first evaluates the performance of this new closed-loop supply chain system considering the quality information disclosure and acquisition, by new models integrating the quality information decisions with the remanufacturing operational decisions. To our knowledge, this paper is an early research of closed-loop supply chain to consider and compare voluntary information disclosure and mandatory information disclosure. (2) The study provides a new decision tool to assist green manufacturers in making decisions on acquiring the quality information from a third-party quality assessment agency before disclosing the quality information. Interestingly, the study finds that the profits of closed-loop supply chain members are higher under the mandatory information disclosure when the green manufacturer refuses to assess the product quality and acquire the information from a third-part quality assessment agency. (3) The study further considers the consumer preference of green products, and get useful managerial insights that the green manufacturer is willing to pay a higher information acquisition cost to acquire the quality information when consumers prefer high quality. (4) Finally, the study provides the practical implications and finds the new condition under which a green manufacturer is willing to disclose the product quality information in closed-loop supply chains.
•A new decision tool for green manufacturers in quality information acquisition.•The new condition for green manufacturer in quality information disclosure.•Consumer preference influences the threshold of quality information acquisition.•Mandatory disclosure and voluntary disclosure in a closed-loop supply chain.•Voluntary disclosure may be not always beneficial to the manufacturer and retailer.
In the last decade, different multi-deep rack climbing robotic (MRR) systems have been introduced, particularly in e-commerce warehouses. These systems have great benefits, as aisles are no longer ...needed, allowing a high storage density on a small footprint. They only need vertical channels through which battery-powered robots can climb the racks, retrieve totes from any desired position, and bring them to a workstation. This paper studies two novel MRR system layouts: the cross and the compact layout. In addition, we compare performance with the more traditional aisle-based layout. The system performance, particularly operational cost and energy consumption, depends on these system layouts. The paper establishes queuing network models to investigate the trade-off between storage capacity and throughput of the system with these three layouts, taking robot blocking prevention into account. We compare the throughput, storage density, horizontal travel time, and energy consumption of the system. The results show that, in most cases, the compact layout outperforms other layouts on throughput. For energy consumption, the choice of layout depends on the footprint. We formulate a model to assist warehouse managers in choosing a layout of minimum annual operational cost, with a required storage and throughput capacity. We also compare the MRR system with an alternative robotic compact storage and retrieval system on operational cost and energy consumption. The MRR system appears to always have lower energy consumption and operational cost.
•We establish models to investigate layout design of a new developed warehouse.•Our model considers the energy consumption and robot blocking.•Our model can choose the layout with minimal cost satisfying performance constraints.•Our model can identify conditions when an MRR system outperform other systems.•We propose a framework to trade-off between storage and throughput capacity.
Storage and retrieval automation has progressed rapidly. One such popular storage and retrieval system deploys two passing aisle-bound cranes. Each crane can access every location in the rack. To ...pass the other crane and prevent collision, each crane has to timely move the platform to an appropriate level and simultaneously rotate it. We develop a queuing model with preemptive-resume interrupted service to estimate the system response time (and hence throughput capacity) while considering two I/O point positions, random storage, and a crane assignment policy where all requests are shared between the cranes. The analytical models are validated with simulation based on the data from real cases. We find that a design with I/O points located in the middle of the rack will increase the interference, but it has a high relative throughput because of the reduced expected travel time. Compared with a system with one crane, a two-crane system has interference, but it can improve the system efficiency, especially in large systems with high job arrival rates. The model can be extended to other systems where multiple cranes are used in a single travel aisle with crane interference, e.g. passing cranes operating in a container stack lane.
While previous studies overlook the collusive behavior of retailers under bidirectional competition, we study a closed-loop supply chain (CLSC) consisting of one manufacturer and two competing ...retailers whose competition exists in the forward and reverse channels. Considering the retailers' potential collusive behavior and the upstream manufacturer's interactive decisions, we build three two-tier game models: Stackelberg-collusion model, Stackelberg-Nash model, and Stackelberg-Stackelberg model. We first obtain the equilibrium decisions of the manufacturer and the retailers in the three models. Furthermore, we investigate whether collusion is beneficial to the two retailers. We find that the retailers' collusion always brings remarkable profit improvement to them as a whole, while the smaller retailers may suffer severe profit loss. A profit-sharing contract is, therefore, designed to guarantee that each retailer can gain more profit by collusion. We also compare the environmental benefit and social welfare among the three models and find that collusion may do harm to the environment or social welfare compared with other models.
•This study investigates whether collusion always bring more profit to retailers.•We consider the retailers' potential collusive behavior.•We study retailers' competition in two directions with three behavior modes.•We find that collusion may do harm to the environment or social welfare.
•We establish models to investigate the battery management in the warehouse.•We find a condition when slow charging outperforms fast charging.•We compare priority charging policy with dedicated ...charging policy.•We find a decision tool to determine the optimal number of chargers.
Our research is motivated by battery management in a new self-climbing robotic (SCR) system. The SCR system fully depends on battery-powered robots for tote movements. Therefore, battery management plays an important role and considerably impacts the system performance. This paper investigates the decision of battery charging technology (fast charging versus slow charging) taking into account the battery degradation, the battery charging policy (priority charging policy and dedicated charging policy), and the optimal number of chargers in the system. The paper also optimizes battery management in the SCR system by establishing semi-open queuing networks (SOQNs). The analytical models are solved by the approximate mean value analysis and are validated by simulation models. We find several interesting managerial insights: (1) In the operational policies, although fast charging can decrease the throughput time, we find a new condition when slow charging outperforms fast charging in robotic warehouses. (2) The priority charging policy is more cost-effective than the dedicated charging policy. (3) We also find a decision tool to determine the optimal number of chargers to satisfy the maximum allowed throughput time with the minimum cost.
•A data-driven method to optimize collection and delivery points locations.•Performances of the models and the results were examined on a real data set.•Our experiments show how to locate collection ...and delivery points explicitly.•We provided a guidance to trade off customer services and logistics cost.
The location of collection and delivery points (CDPs), impacted by online customers’ demand data, plays an important role for online retailers. While previous delivery points optimization researches do not use customer behavior data, we propose new models, integrating with customer behavior data analysis, to optimize collection and delivery points for online retailers. We explore a real customer behavior data and use totally 257,685 users’ records (212,062 records for training set and 45,623 records test set). We first estimate the customer purchase probability by five data mining models. Based on the estimation results, we establish two facility location models to respectively optimize the attended and unattended CDPs locations with the objective of cost minimization. Our numerical experiments make a quantitative analysis of customer service level and location cost. Our results can further help online retailers to decide the suitable CDPs with trading off the consumer service level and the total logistics cost. We make interesting contributions: (i) we analyze real customer behavior data and find that gradient boosting trees algorithm outperform other four algorithms when estimating customers’ purchase probabilities; (ii) We propose a new data-driven method integrating data mining models and facility location models to determine CDP locations for online retailers.
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•Single NPS reduces H2-production by 53.9%, while combined NPS + PFOS decrease by 31.6%.•The combined toxicity of NPS + PFOS is antagonistic relative to single NPS.•Single NPS and ...combined NPS + PFOS alter the properties, structure and function of EPS.•Single NPS and combined NPS + PFOS increase permeability and induce oxidative stress.
As a carrier of perfluorooctane sulfonate, nano-plastics are ubiquitous and finally enriched in the sludge, which is widely used as a raw material for the production of bioenergy (hydrogen or methane) by anaerobic digestion. However, there are still many unknowns about their metabolic toxicity to functional microbes (e.g. hydrogen-producing thermophilic bacteria). Therefore, single and combined effects of amino polystyrene (NPS: 70 nm; 0.2 mg/L) and perfluorooctane sulfonate (PFOS: 0.1, 1 and 5 mg/L) on hydrogen-producing thermophilic bacteria were investigated after exposure for 7 days at 55 °C and pH = 5.7. Single NPS exhibited obvious interference to the metabolism of thermophilic bacteria, resulting in a 53.9% reduction in hydrogen production. However, the combined NPS + PFOS produced an antagonistic effect, leading to a 31.6% reduction in hydrogen production. Nonetheless, the single and combined exposure did not alter the type of hydrogen production (acetic acid-type hydrogen fermentation). Moreover, single NPS and combined NPS + PFOS not only induced the changes of the composition of extracellular polymers (EPSs) and π bond structure of the protein in EPSs, but also decreased the activity of hydrolase in EPSs and surface charge of EPSs. Compared to single NPS exposure, NPS + PFOS-exposed thermophilic bacteria was less permeable to a semi-membrane permeable dye and produced less reactive oxygen species, but were still significantly higher than control group. In short, the main mechanisms of single NPS and combined NPS + PFOS were both to increase cell permeability and to induce oxidative stress. The addition of PFOS alleviated the toxic effect of NPS, but did not change its mechanism of toxicity.
•A logistics response model to a bioterrorist anthrax attack is proposed.•It combines disease progress, medical responses, and logistic deployment choices.•It takes into account the main factors ...which may impact the number of deaths.•Crisis managers could estimate the number of individuals in different stages.•The model is flexible and can be adapted to various situations.
As a bioterrorist anthrax attack has serious consequences, an emergency management plan that can reduce the number of casualties should be studied. However, the papers studying this area are still few. This paper proposes a model which links the disease progression, the related medical intervention actions and the logistics deployment together to help crisis managers to extract crucial insights on emergency logistics management from a strategic level standpoint. This model is a multi-period one with the consideration of the period when the patients transfer into the different disease stages, the period when the medical intervention begins and the change of the recovery rate because of the time lag between the two aforementioned periods. Our model can support the decision making process in case of a real anthrax attack and evaluate the important factors, which can have a great impact on the number of casualties.
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