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Background: After hypovolemic shock caused by severe burns, lipid peroxidation is an important factor in tissue edema and multiorgan dysfunction syndrome (MODS). Many studies have shown that valproic acid (VPA) inhibits lipid peroxidation and reduces tissue and organ injury. Objectives: This study investigated whether the VPA treatment of scalded rats reduced tissue edema by inhibiting lipid peroxidation, thereby improving organ function and survival rate. Materials and Methods: A total of 60 male Sprague-Dawley rats (weighing: 280–300 g) with a 50% total body surface area (TBSA) full-thickness dermal burn were randomly assigned to the following 3 groups (with 20 rats per group): (I) the no infusion resuscitation (NR) group; (II) the sodium lactate Ringer's solution (LR) group; and (III) the sodium valproate Ringer's solution (VR) group. After scalding, the following hemodynamic parameters were measured: Copper2+-Zinc2+-superoxide dismutase (Cu2+-Zn2+-SOD) activity, thiobarbituric acid reactive substances (TBARSs), oxidized glutathione (GSSG), reduced glutathione (GSH), and antioxidant enzyme activities. Organ function parameters and water content were also measured. Another 60 male Sprague-Dawley rats were used to observe the 24-h survival rate of the rats using the same scald model and fluid resuscitation. Results: VPA significantly increased the mean arterial pressure (MAP) and cardiac output (CO), and significantly decreased the pulmonary vascular permeability index (PVPI) and extravascular lung water index (ELWI). VPA also increased plasma Cu2+-Zn2+-SOD activity and decreased the plasma TBARS level. VPA reduced the TBARS level and GSSG in various tissues and increased the concentration of GSH. VPA decreased glutathione peroxidase (GPx) and catalase (CAT) activity, but significantly increased glutathione reductase (GR) activity in various tissues. VPA significantly improved organ functions and decreased water content. VPA significantly improved the survival rate, and the 24-h survival rate of the VR group was double that of the LR group. Conclusion: Resuscitation with VPA reduced tissue edema, protected visceral functions, and improved the survival rate of rats with severe burn shock (BS) by alleviating lipid peroxidation. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the safety and effectiveness of intra-sac thrombin injection to remedy type II endoleaks (T2ELs) during endovascular aneurysm repair (EVAR). Materials and Methods: 224 cases abdominal aortic aneurysm (AAA) were treated with EVAR. For the 52 cases of intra-operative type II endoleaks and 8 cases of ruptured AAAs, after the grafts were deployed, thrombin was injected into the aneurysm sac through a preset catheter. The occurrence of endoleaks post-EVAR were followed up with by Computed Tomography (CT) angiogram. The diameter and the volume of the aneurysm sac were also measured. Endpoints included incidence of T2ELs, AAA sac shrinkage and re-intervention rate and all-cause mortality. Results: The overall technical success rate was 100%. Fifty-two patients were followed up with for 9-56 (median 24) months. No serious complications were observed during follow-up. The incidence of endoleak was 5.8% (3/52) during follow-up. The maximum diameter of the aneurysm decreased from 61.1 ± 14.2 mm to 53.7 ± 10.6 mm, 47.9 ± 8.3 mm and 43.7 ± 7.2 mm (87.9%, 78.4% and 71.5% of pre-EVAR) at the 6-month, 1-year and 2-year follow-up, respectively (P <.05). The volume of the aneurysm sac shrank from 236.2 ± 136.2 cm3 to 202.6 ± 114.1 cm3, 155.6 ± 68.4 cm3 and 129.7 ± 52.4 cm3 (85.8%, 65.9%, and 54.9% of pre-EVAR) at the 6-month, 1-year and 2-year follow-up, respectively (P <.05). The rate of various endoleaks was 5.8% (3/52) and the re-intervention rate was 1.9% (1/52) in this research. Conclusions: Clinical outcomes show that intra-sac injection of thrombin during EVAR is safe and may be effective in remedying small amount and low-velocity endoleaks and promoting shrinkage of the aneurysm sac. [ABSTRACT FROM AUTHOR]

The uncertainty in the supplier's material flows has become a norm rather than an exception in supply chains. The supply uncertainty can result in unexpected inventory shortfall, amplifying lost sales. However, the design of inventory replenishment and product pricing policy to mitigate both supply uncertainty and demand loss remains unexplored. This is because the resulting dynamic planning problem is highly nonconcave and thus intractable. To address this challenge, we propose an approach that focuses on a class of intuitively appealing and practically plausible policies. Specifically, as the level of on-hand inventory increases, we expect an increased amount of demand fulfillment and a decreased product price. Applying the notions of stochastic functions, we show that, under general conditions of the stochastic supply and demand functions, the dynamic planning problem becomes a concave optimization problem over the restricted policy class. We further reduce the set of candidate policies to a refined class by excluding the dominated policies. A refined policy can be easily computed, and appropriately selected refined policies produce close-to-optimal profits. These developments allow us to evaluate the consequences of demand loss. In particular, demand retention through backordering can be beneficial when overstocking is costly in relation to understocking, but the benefit is insensitive to supply and demand uncertainties. Moreover, inventory-based dynamic pricing is more valuable in mitigating supply risk under lost sales than under backordering. [ABSTRACT FROM AUTHOR]

This paper introduces the general philosophy of the Operational Data Analytics (ODA) framework for data‐based decision modeling. The fundamental development of this framework lies in establishing the direct mapping from data to decision by identifying the appropriate class of operational statistics. The efficient decision making relies on a careful balance between data integration and decision validation. Through a canonical decision making problem under uncertainty, we show that the existing approaches (including statistical estimation and then optimization, retrospective optimization, sample average approximation, regularization, robust optimization, and robust satisficing) can all be unified through the lens of the ODA formulation. To make the key concepts accessible, we demonstrate, using a simple running example, how some of the existing approaches may become equivalent under the ODA framework, and how the ODA solution can improve the decision efficiency, especially in the small sample regime. [ABSTRACT FROM AUTHOR]

The purpose of this study is to explore the effect of using 3D printed pelvic prosthesis to reconstruct bone defect after pelvic tumor resection. From June 2018 to October 2021, a total of 10 patients with pelvic tumors underwent pelvic tumor resection and 3D printed customized hemipelvic prosthesis reconstruction in our hospital. Enneking pelvic surgery subdivision method was used to determine the degree of tumor invasion and the site of prosthesis reconstruction. 2 cases in Zone I, 2 cases in Zone II, 3 cases in Zone I + II, 2 cases in Zone II + III and 1 case in Zone I + II + III. Patients had preoperative VAS scores of 6.5 ± 1.3, postoperative VAS scores of 2.2 ± 0.9, preoperative MSTS-93 scores of 9.4 ± 5.3 and postoperative 19.4 ± 5.9(p < 0.05), all patients had improvement in pain after surgery; Postoperative complications included joint dislocation in 2 cases, myasthenia caused by Guillain-Barre syndrome in 1 case, delayed wound healing in 3 cases and wound infection in 2 cases. Postoperative wound-related complications and dislocations were associated with the extent of the tumor. Patients with tumor invasion of the iliopsoas and gluteus medius muscles had higher complication rates and worse postoperative MSTS scores (p < 0.05). The patients were followed up for 8 ∼ 28 months. During the follow-up period, 1 case recurred, 4 cases metastasized and 1 case died. All pelvic CTs reviewed 3–6 months after surgery showed good alignment between the 3D printed prosthesis and the bone contact, and tomography showed the growth of trabecular structures into the bone. Overall pain scores decreased and functional scores improved in patients after 3D printed prosthesis replacement for pelvic tumor resection. Long-term bone ingrowth could be seen on the prosthesis-bone contact surface with good stability. [ABSTRACT FROM AUTHOR]

In this article, we describe representative contributions in several major application areas of data analytics in operations management to summarize the recent development, discuss the common themes, identify the current trends, and speculate the future directions. Certainly, many important contributions have been made in various application areas that are either directly or indirectly related to data analytics, and there are important theoretical developments made by scholars in our field. It is not our intention to provide a complete survey for data‐analytics work in our field. Instead, we focus only on the aspect of data integration in operational decision‐making by describing the most popular applications of data analytics. [ABSTRACT FROM AUTHOR]

As a follow-up work of previous experimental efforts, this paper aims to further explore the compressive behavior of Steel Reinforced Concrete (SRC) composite beam-columns with assistance of nonlinear Finite Element Analysis. The FE model was developed in ABAQUS software and it delivered desirable accuracy after calibrating against the dataset collected from published literatures. The validated FE model was then employed to evaluate the fundamental performance of SRC beam-columns under uniaxial eccentric compression and biaxial eccentric compression. On top of that, the fiber section analysis was adopted to build the three-dimensional axial force-bending moment (N-M) interaction diagrams, followed by a parametric study to investigate the effect of material grade, steel ratio, cross-section geometry, load eccentricity and load inclination on the load-carrying capacity of SRC beam-columns, and disclose the complex biaxial interaction mechanism that is not well-considered in current design codes. Based on the numerical data generated from parametric study, the Support Vector Machine method is utilized to intelligently estimate the biaxial moment contours under varying load levels, which exhibits improved accuracy and consistency than the code-specified method and conventional empirical formulae. [ABSTRACT FROM AUTHOR]

Substitution is a commonly adopted strategy for matching the demand mix by appropriately allocating the supplies. The recent development of information technology has allowed firms to easily swap products to meet consumers' preferences. When formulating substitution policies, firms have to take into account the supply and demand conditions, as well as the cost and benefit of substitution. We formulate a dynamic model, in which the firm replenishes the product inventories from uncertain sources and dynamically allocates the available products to meet the uncertain demands with the flexibility of substitution. To address the analytical challenge associated with multi‐product management, we develop a heuristic algorithm that leverages the value of substitution, while allowing separability of future profit among the products. This heuristic algorithm iteratively solves a transportation problem in a network with the reverse Monge property. The application of the reverse Monge property allows us to deal with general substitution structures, which generalizes the commonly studied downward substitution models. Given the product inventories, the derived allocation policy is asymptotically optimal when the firm can frequently remix the products to fulfill the received demands. Through an extensive numerical analysis, we demonstrate that the heuristic policy yields good performance measured by the percentage profit gap from an upper bound problem. We also show that substitution can generate significant benefits when the supply capacities are moderate, the supply and demand uncertainties are high, or the replenishment cycle is short. [ABSTRACT FROM AUTHOR]

Uncertainties involved in decision making often impose challenges to our ability of modeling and analyzing the reality. The purpose of this study is to demonstrate how one can go beyond the conventional optimization thinking, via taking a stochastic viewpoint, to push the boundaries of the analysis. We review the basic notions of stochastic orders and stochastic functions, with which the conventional (deterministic) way of modeling can be generalized. Based on the orders among distribution functions associated with random variables, we can treat the input–output relationship as stochastic functions in our models. This viewpoint, leads to extended functional properties in the stochastic sense. Taking the existing models involving inventory and pricing decisions, we show how the stochastic notions are powerful in simplifying and generalizing the analysis, as well as generating new insights. [ABSTRACT FROM AUTHOR]

Choice models are widely applied in psychology, economics, transportation, marketing, and operations studies. We review the existing developments on the modeling of consumers' choices, including the attraction model, the utility‐based model, the temporal model, and the rank‐based model. The relationships among different classes of structural models are established and analyzed. Moreover, an operational data analytics (ODA) framework is presented to estimate the general consumer choice model using data. This framework, generalizing the existing estimation methods for specific structural models, strikes a delicate balance between the (likely imprecise) structural knowledge and the data. This is achieved by articulating the domain of validation through extending the structural knowledge and by formulating the data‐integration model based on the associated structural properties. We demonstrate the implementation of the ODA framework to identify the appropriate consumer choice models. The ODA estimate outperforms the existing parametric and nonparametric methods, particularly over the choice sets that are not covered in the data. We also discuss potential future research of developing ODA approaches to study the related aspects of consumer choice models. [ABSTRACT FROM AUTHOR]

Objectives: The present study was designed to assess outcomes of patients undergone radiofrequency ablation (RFA) for their incompetent perforator veins (IPVs) with ClosureFast stylets. Methods: Data of 165 IPVs in 138 limbs of 117 consecutive patients between July 2017 to Nov. 2019 were retrospectively reviewed. Primary endpoints (technical success rate, complications) and secondary endpoints (VCSS) were analyzed. Results: The immediate technical success rate was 100%. There were no major complications. The rate of ecchymosis and induration was 5.8%. 129/165 IPVs in 79.5% (93/117) patients had achieved sonographic evaluation at 1 year followed-up, in which 3 perforators were recanalized. VCSS scores at pre-operation and 1-year follow-up were 5.77 ± 1.88 and 2.70 ± 1.39, respectively (t = 29.644, P =.000). Conclusions: In conclusion, RFA is safe and effective for the treatment of IPVs. At the 1-year follow-up, the RFA of IPVs showed a low recanalization rate and had a satisfactory improvement on VCSS. [ABSTRACT FROM AUTHOR]

Ni(NH3)4(AFT)2 [NiC6H16N18O2, AFT = 4-amino-3-(5-tetrazolate)furazan] is synthesized and characterized by elemental analysis and Fourier-transform infrared spectroscopy for the first time. X-ray diffraction measurements are used to determine the crystal structure of compound 1. The results demonstrate that compound 1 crystallized in the orthorhombic crystal system. The nickel(II) ion is six-coordinated by N atoms from two AFT-ligands and four NH3 molecules. Its thermal properties are investigated by differential scanning calorimetry and thermogravimetry-derivative thermogravimetry methods, with the results demonstrating that the differential scanning calorimetry curve exhibits two endothermic and one exothermic processes. The endothermic processes are in the range of 130–510 °C with a peak temperature of 188 °C. The temperature from 230 to 400 °C is the exothermic process in which the peak temperature is 314.58 °C. In addition, Kissinger's and Ozawa-Doyle's methods are used for calculating the non-isothermal kinetics parameters. Moreover, the apparent activation energy (E), safety, and thermal stability parameters (T SADT, T TIT, T b) for Ni(NH3)4(AFT)2 are calculated. In addition, the calculated thermodynamic functions (∆S ≠, ∆H ≠, and ∆G ≠) for the exothermic decomposition process of Ni(NH3)4(AFT)2 are 55.07 J mol−1 K−1, 196.18 kJ mol−1, and 164.90 kJ mol−1, respectively. [ABSTRACT FROM AUTHOR]

With supply chains becoming increasingly extended, the uncertainties in the upstream production process can greatly affect the material flows that aim toward meeting the uncertain demands at the downstream. We analyze a two‐location system in which the upstream production facility experiences random capacities and the downstream store faces random demands. Different from the widely used approach that seeks the decomposition of the profit function based on the echelon inventories, our approach builds on the notions of stochastic functions, in particular, the stochastic linearity in midpoint and the directionally concave order. With these notions, we establish the concavity and submodularity of the profit functions in the transformed decision variables. In general, it is optimal to follow a two‐level state‐dependent threshold policy such that an order is issued at a location if and only if the inventory position of that location is below the corresponding threshold. In the special case where the salvage values are linear in the ending inventories, the profit function becomes separable in the inventory positions, and the optimal policy reduces to the echelon base‐stock policy. The effect of the uncertain capacity and demand depends critically on whether the production capacity is limited or ample in relation to the demand. Only when the capacity and the demand do not differ much, the upstream facility carries positive inventory; otherwise, all units produced are shipped immediately toward the downstream. We further extend our analysis to systems with general stochastic production functions and with multiple locations. [ABSTRACT FROM AUTHOR]

Background: Myofascial pain syndrome (MPS) is an important clinical condition that is characterized by chronic muscle pain and a myofascial trigger point (MTrP) located in a taut band (TB). Previous studies showed that EphrinB1 was involved in the regulation of pathological pain via EphB1 signalling, but whether EphrinB1-EphB1 plays a role in MTrP is not clear. Methods: The present study analysed the levels of p-EphB1/p-EphB2/p-EphB3 in biopsies of MTrPs in the trapezius muscle of 11 MPS patients and seven healthy controls using a protein microarray kit. EphrinB1-Fc was injected intramuscularly to detect EphrinB1s/EphB1s signalling in peripheral sensitization. We applied a blunt strike to the left gastrocnemius muscles (GM) and eccentric exercise for 8 weeks with 4weeks of recovery to analyse the function of EphrinB1/EphB1 in the muscle pain model. Results: P-EphB1, p-EphB2, and p-EphB3 expression was highly increased in human muscles with MTrPs compared to healthy muscle. EphB1 (r=0.723, n=11, P<0.05), EphB2 (r=0.610, n=11, P<0.05), and EphB3 levels (r=0.670, n=11, P<0.05) in the MPS group were significantly correlated with the numerical rating scale (NRS) in the MTrPs. Intramuscular injection of EphrinB1-Fc produces hyperalgesia, which can be partially prevented by pre-treatment with EphB1-Fc. The p-EphB1 contents in MTrPs of MPS animals were significantly higher than that among control animals (P<0.01). Intramuscular administration of the EphB1 inhibitor EphB1-Fr significantly suppressed mechanical hyperalgesia. Conclusions: The present study showed that the increased expression of p-EphB1/p-EphB2/p-EphB3 was related to MTrPs in patients with MPS. This report is the first study to examine the function of EphrinB1-EphB1 signalling in primary muscle afferent neurons in MPS patients and a rat animal model. This pathway may be one of the most important and promising targets for MPS. [ABSTRACT FROM AUTHOR]

When firms post prices to sell their products in a competitive market, buyers often seek to bargain down the prices. The existing studies on dynamic competition, however, focus on firms' dynamic pricing strategies without considering the possibility of bargaining. We model a random stream of buyers with heterogeneous valuations who may choose to negotiate for a discount from a posted price. When bargaining is allowed, a seller firm's competing strategy depends not only on her reservation value (i.e., her gain from an unsold item when losing the current buyer to the opponent) but also on her disagreement point (i.e., the value of an unsold item when the negotiation with an arriving buyer breaks down). We show that the reservation values and the disagreement points can play opposite roles in competition—the seller firms' posted prices are increasing in their reservation values but are decreasing in their disagreement points. In general, a seller becomes more aggressive in price competition when her reservation value becomes lower. However, it is not always the case that a seller with a lower reservation value can successfully win the deal from an arriving buyer, as it is in pure price competition. Because of the possibility of bargaining, the buyer may end up purchasing from a seller who has a higher inventory level and a higher reservation value when the seller's disagreement point is lower than that of her opponent. Interestingly, such an equilibrium outcome can only arise when the selling season is sufficiently long. Our analysis highlights the intriguing role played by negotiation in dynamic competition for sequential selling. [ABSTRACT FROM AUTHOR]

We study a retailer's sourcing contract when the supplier's reservation profit (offered by his outside options) depends on his cost, which is privately known to only the supplier. An interesting discovery from our analysis is that supply chain coordination may be achieved despite the information asymmetry between the two firms regarding the supplier's type (i.e., his cost). This happens when the marginal contribution of the supplier's cost efficiency to the trade matches with the supplier's marginal reservation profit. In this case, the optimal contract quantities maximize the supply chain profits for the respective supplier types, and no information rent is paid to any supplier type. For the general case, we show that, regardless of his type, the supplier may have an incentive to overstate or understate his cost, depending on whether or not his marginal contribution to the trade exceeds his marginal reservation profit. We demonstrate six possible forms of the optimal contract. Observations from our analysis contrast with those derived from previous studies, complementing the theory of countervailing incentives. [ABSTRACT FROM AUTHOR]

We are living in an era in which data is generated in huge volume with high velocity and variety. Big Data and technology are reshaping our life and business. Our research inevitably needs to catch up with these changes. In this short essay, we focus on two aspects of supply chain management, namely, demand management and manufacturing. We feel that, while rapidly growing research on these two areas is contributed by scholars in computer science and engineering, the developments made by production and operations management society have been insufficient. We believe that our field has the expertise and talent to push for advancements in the theory and practice of demand management and manufacturing (of course, among many other areas) along unique dimensions. We summarize some relevant concepts emerged with Big Data and present several prototype models to demonstrate how these concepts can lead to rethinking of our research. Our intention is to generate interests and guide directions for new research in production and operations management in the era of Big Data. [ABSTRACT FROM AUTHOR]

Subsidy programs are widely offered in both developing and developed countries to encourage consumption of products that generate positive social, health, and environmental externalities. We study the effect of subsidies on product consumption under uncertain market demand. To reach a target consumer population, the program sponsor may subsidize a for-profit or a not-for-profit firm on each unit of the product purchased by the firm or on each unit of the sale generated by the firm. We show that subsidy programs provide stronger incentives to a not-for-profit firm than to its for-profit counterpart in inducing a large consumption whenever the sponsor is having a very limited budget or a very generous budget. When subsidizing a not-for-profit firm, the sponsor should always choose the purchase subsidy over the sales subsidy because the former can induce a larger consumption than the latter with the same subsidy spending. However, this is not always true when the subsidy program is administered through a for-profit firm, unless the firm is a price taker in the market or the sponsor has a limited budget. Our analysis leads to new theoretical development of price-setting newsvendor problem for both the for-profit and not-for-profit operations under subsidy. [ABSTRACT FROM AUTHOR]

Background: Assessment of intestinal activity and severity of Crohn’s disease (CD) is crucial to guide treatment. In this study, we aimed to investigate the accuracy of spectral computed tomography (CT) in this assessment and make a comparison with conventional CT. Methods: A total of 50 patients with ileocolonic CD underwent spectral CT scanning. Conventional CT and spectral CT images were reconstructed. Endoscopic lesions were classified as absent, mild lesions and severe lesions. Qualitative and quantitative findings in CT images were compared in these segments. Logistic regressions were established, based on conventional and spectral CT parameters, to predict intestinal activity and severity. Comparisons were made by receiver operating characteristic (ROC) curve. Results: The results showed that bowel wall hyperenhancement, ulcers on CT images, comb sign, bowel wall thickness, normalized iodine concentration (NIC) and slope of HU curve (λHU) increased significantly (p < 0.01) with endoscopic severity. In predicting intestinal activity, spectral CT demonstrated higher accuracy (99.6% versus 94.7%), sensitivity (99.1% versus 93.4%) and specificity (99.9% versus 94.4%) than conventional CT. In predicting intestinal severity, spectral CT also had higher accuracy (96.5% versus 91.9%), sensitivity (96.5% versus 92.1%) and specificity (95.8% versus 89.8%) than conventional CT. Besides, both NIC and λHU correlated significantly with Simple Endoscopic Score for CD (r = 0.833 and r = 0.771; both p < 0.001), but their correlations with C-reactive protein (r = 0.578 and r = 0.513; both p < 0.01) and Harvey–Bradshaw Index (r = 0.545 and r = 0.522; both p < 0.01) were moderate. Conclusions: Compared with conventional CT, spectral CT had higher accuracy in detecting intestinal activity and severity of CD, which could be an alternative choice in evaluation of CD. [ABSTRACT FROM AUTHOR]

Big data has the potential of offering valuable insights into the way organizations function, and it is changing the way organizations make decisions. Nine invited essays provide a wide range of perspectives on the role of big data in customer‐driven supply chains, healthcare operations, retail operations, demand planning and manufacturing, environmental and social issues, humanitarian operations, agriculture supply chains, and service operations. Decision makers should have clean, valid, and reliable data, and they should have a thorough understanding of the contexts of applications. Big data shorten virtual distance to customers, and thus facilitate personalization of products and services. Successful implementation of big data applications requires sharing the data with appropriate stakeholders. [ABSTRACT FROM AUTHOR]

Sourcing from multiple suppliers with different characteristics is common in practice for various reasons. This paper studies a dynamic procurement planning problem in which the firm can replenish inventory from a fast and a slow supplier, both with uncertain capacities. The optimal policy is characterized by two reorder points, one for each supplier. Whenever the pre-order inventory level is below the reorder point, a replenishment order is issued to the corresponding supplier. Interestingly, the reorder point for the slow supplier can be higher than that of the fast even if the former has a higher cost, lower reliability, and smaller capacity than the latter, suggesting the possibility of ordering exclusively from an inferior slow supplier in the short term. Moreover, the firm may allocate a larger portion of the long-term total order quantity to the slow supplier than to the fast, even if the former does not possess any cost or reliability advantage over the latter. Such phenomena, different from the observations made in previous studies, happen when the demand is uncertain and the supply is limited or unreliable. Our observations highlight the importance of incorporating both demand uncertainty and supplier characteristics (i.e., cost, lead time, capacity and uncertainty) in a unified framework when formulating supplier selection and order allocation strategies. [ABSTRACT FROM AUTHOR]

We study an average-cost stochastic inventory control problem in which the firm can replenish inventory and adjust the price at anytime. We establish the optimality to change the price from low to high in each replenishment cycle as inventory is depleted. With costly price adjustment, scale economies of inventory replenishment are reflected in the cycle time instead of lot size-An increased fixed ordering cost leads to an extended replenishment cycle but does not necessarily increase the order quantity. A reduced marginal cost of ordering calls for an increased order quantity, as well as speeding up product selling within a cycle. We derive useful properties of the profit function that allows for reducing computational complexity of the problem. For systems requiring short replenishment cycles, the optimal solution can be easily computed by applying these properties. For systems requiring long replenishment cycles, we further consider a relaxed problem that is computational tractable. Under this relaxation, the sum of fixed ordering cost and price adjustment cost is equal to (greater than, less than) the total inventory holding cost within a replenishment cycle when the inventory holding cost is linear (convex, concave) in the stock level. Moreover, under the optimal solution, the time-average profit is the same across all price segments when the inventory holding cost is accounted properly. Through a numerical study, we demonstrate that inventory-based dynamic pricing can lead to significant profit improvement compared with static pricing and limited price adjustment can yield a benefit that is close to unlimited price adjustment. To be able to enjoy the benefit of dynamic pricing, however, it is important to appropriately choose inventory levels at which the price is revised. [ABSTRACT FROM AUTHOR]

Despite the spread of cost-driven outsourcing practices, academic research cautions that suppliers' cost advantage may weaken manufacturers' bargaining positions in negotiating outsourcing agreements, thereby hurting their profitability. In this study, we attempt to further understand the strategic impact of low-cost outsourcing on manufacturers' profitability by investigating the contractual form of outsourcing agreements and the industry structure of the upstream supply market. We consider a two-tier supply chain system, consisting of two competing manufacturers, who have the option to produce in-house or to outsource to an upstream supplier with lower cost. To reach an outsourcing agreement, each manufacturer engages in bilateral negotiation with her supplier, who may be an exclusive supplier or a common supplier serving both manufacturers. Our analysis shows that wholesale-price contracts always mitigate the competition between manufacturers regardless of whether they compete with price or quantity. In contrast, two-part tariffs intensify the competition when the manufacturers compete with quantity, but soften it when they compete with price. As a result, when outsourcing with two-part tariffs, the manufacturers may earn lower profits than they would from in-house production, although the suppliers are more cost efficient. This suggests that managers have to be wary about the downside of using coordinating contracts such as two-part tariffs when pursuing low-cost outsourcing strategies. Our analysis also sheds some light on the profitability of using an exclusive supplier for outsourcing. When outsourcing with wholesale-price contracts, the competing manufacturers are better off outsourcing to an exclusive supplier. However, when outsourcing with two-part tariffs, the manufacturers may earn higher profits by outsourcing to a common supplier than to an exclusive one when the manufacturers' bargaining power is sufficiently strong (weak) under quantity (price) competition. [ABSTRACT FROM AUTHOR]

We analyze contracting behaviors in a two-tier supply chain system consisting of competing manufacturers and competing retailers. We contrast the contracting outcome of a Stackelberg game, in which the manufacturers offer take-it-or-leave-it contracts to the retailers, with that of a bargaining game, in which the firms bilaterally negotiate contract terms via a process of alternating offers. The manufacturers in the Stackelberg game possess a Stackelberg-leader advantage in that the retailers are not entitled to make counteroffers. Our analysis suggests that whether this advantage would benefit the manufacturers depends on the contractual form. With simple contracts such as wholesale-price contracts, which generally do not allow one party to fully extract the trade surplus, the Stackelberg game replicates the boundary case of the bargaining game with the manufacturers possessing all the bargaining power. In contrast, with sophisticated contracts such as two-part tariffs, which enable full surplus extraction, the two games lead to distinct outcomes. We further show that the game structure being Stackelberg or bargaining critically affects firms' preferences over contract types and thus their equilibrium contract choices. These observations suggest that the Stackelberg game may not be a sufficient device to predict contracting behaviors in reality where bargaining is commonly observed. [ABSTRACT FROM AUTHOR]

We analyze a model that integrates demand shaping via dynamic pricing and risk mitigation via supply diversification. The firm under consideration replenishes a certain product from a set of capacitated suppliers for a price-dependent demand in each period. Under deterministic capacities, we derive a multilevel base stock list price policy and establish the optimality of cost-based supplier selection, that is, ordering from a cheaper source before more expensive ones. With general random capacities, however, neither result holds. While it is optimal to price low for a high inventory level, the optimal order quantities are not monotone with respect to the inventory level. In general, a near reorder-point policy should be followed. Specifically, there is a reorder point for each supplier such that no order is issued to him when the inventory level is above this point and a positive order is placed almost everywhere when the inventory level is below this point. Under this policy, it may be profitable to order exclusively from the most expensive source. We characterize conditions under which a strict reorder-point policy and a cost-based supplier-selection criterion become optimal. Moreover, we quantify the benefit from dynamic pricing, as opposed to static pricing, and the benefit from multiple sourcing, as opposed to single sourcing. We show that these two strategies exhibit a substitutable relationship. Dynamic pricing is less effective under multiple sourcing than under single sourcing, and supplier diversification is less valuable with price adjustments than without. Under limited supply, dynamic pricing yields a robust, long-term profit improvement. The value of supply diversification, in contrast, mainly comes from added capacities and is most significant in the short run. [ABSTRACT FROM AUTHOR]

We analyze a supply chain consisting of a supplier and a retailer. The supplier's unit production cost, which characterizes his type, is only privately known to him. When trading with the retailer, the supplier demands a reservation profit that depends on his unit production cost. We model this problem as a game of adverse selection. In this model, the retailer offers a menu of contracts, each of which consists of two parameters: the ordering quantity and the supplier's share of the channel profit. We show that the optimal contract depends critically on a surrogate measure-the ratio of the types' reservation profit differential to their production cost differential. An important implication from our analysis is that information asymmetry alone does not necessarily induce loss in channel efficiency. The optimal contract can coordinate the supply chain as long as the low-cost supplier's cost efficiency is neither much overvalued nor much undervalued in the outside market. We further discuss the retailer's preference of the supplier's type under different market conditions, as well as evaluate the effects of the supplier's reservation profit, the retail price, and the demand uncertainty on the optimal contract. [ABSTRACT FROM AUTHOR]

Information delays exist in an inventory system when it takes time to collect, process, validate, and transmit inventory/demand data. A general framework is developed in this paper to describe information flows in an inventory system with information delays. We characterize the sufficient statistics for making optimal decisions. When the ordering cost is linear, the optimality of a state-dependent base-stock policy is established even when information flows are allowed to cross over time. Additional insights into the problem are obtained via a comparison between our models and the models with stochastic order lead times. We also show that inventory can substitute for information and vice versa. [ABSTRACT FROM AUTHOR]

The objective of this study was to identify the potential risk factors of metabolic syndrome (MetS) among Chinese schoolchildren. A cross-sectional study among 624 children (357 boys and 267 girls, aged 9.6 ± 0.7 years) was conducted in Wuhan, China, from May to June 2010. MetS was defined according to the criteria proposed by De Ferranti and the International Diabetes Federation (IDF) criteria. Data on cardiorespiratory fitness (CRF), household income, parental hypertension, and children’s personal information, including birth weight, preterm birth, and breast-feeding, reported by their parents were obtained. Multiple logistic regression showed that CRF (odds ratio [OR] = 0.68; 95% confidence interval [CI] = 0.60-0.77), breast-feeding (OR = 0.32; 95% CI = 0.10-0.97), and paternal hypertension (OR = 5.06; 95% CI = 1.20-21.37) were all independently associated with MetS. In conclusion, low CRF and paternal hypertension significantly increase the risk, whereas breast-feeding may reduce the risk of MetS among Chinese schoolchildren. [ABSTRACT FROM PUBLISHER]

Ni(NH3)4(AFT)2 [NiC6H16N18O2, AFT = 4-amino-3-(5-tetrazolate)furazan] is synthesized and characterized by elemental analysis and Fourier-transform infrared spectroscopy for the first time. X-ray diffraction measurements are used to determine the crystal structure of compound 1. The results demonstrate that compound 1 crystallized in the orthorhombic crystal system. The nickel(II) ion is six-coordinated by N atoms from two AFT-ligands and four NH3 molecules. Its thermal properties are investigated by differential scanning calorimetry and thermogravimetry-derivative thermogravimetry methods, with the results demonstrating that the differential scanning calorimetry curve exhibits two endothermic and one exothermic processes. The endothermic processes are in the range of 130–510 °C with a peak temperature of 188 °C. The temperature from 230 to 400 °C is the exothermic process in which the peak temperature is 314.58 °C. In addition, Kissinger's and Ozawa-Doyle's methods are used for calculating the non-isothermal kinetics parameters. Moreover, the apparent activation energy (E), safety, and thermal stability parameters (T SADT, T TIT, T b) for Ni(NH3)4(AFT)2 are calculated. In addition, the calculated thermodynamic functions (∆S ≠, ∆H ≠, and ∆G ≠) for the exothermic decomposition process of Ni(NH3)4(AFT)2 are 55.07 J mol−1 K−1, 196.18 kJ mol−1, and 164.90 kJ mol−1, respectively. [ABSTRACT FROM AUTHOR]