409 research outputs found

    Tree Ring Characteristics of 30-Year-Old Swietenia Macrophylla Plantation Trees

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    Ring characteristics of mahogany (Swietenia macrophylla K.) plantation trees grown in Taiwan were explored. Significant differences in average ring width (RW) and ring density (RD) occurred among three tree-diameter classes and three radial stages of ring numbers. RW in the radial direction decreased from the pith outward to the bark and followed a distinctive three-stage variation pattern (juvenile, transition, and mature zones). RD in the radial direction increased slowly from the pith outward to the bark. Wider tree rings and lower density are associated with juvenile wood close to the pith, whereas narrower tree rings and higher density are typical for mature wood outward toward the bark. RD in overtopped trees was higher than that in dominant trees. However, RW in dominant trees was wider than that in intermediate and overtopped trees. Earlywood density, latewood density, maximum density, and minimum density were the most important factors determining overall RD. There was a weak relationship between RW and RD, indicating that it is unlikely for growth rates of mahogany plantation trees to have a significant impact on wood density

    Retailer’s optimal pricing and ordering policies for non-instantaneous deteriorating items with price-dependent demand and partial backlogging

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    [[abstract]]An inventory system for non-instantaneous deteriorating items with price-dependent demand is formulated and solved. A model is developed in which shortages are allowed and partially backlogged, where the backlogging rate is variable and dependent on the waiting time for the next replenishment. The major objective is to determine the optimal selling price, the length of time in which there is no inventory shortage, and the replenishment cycle time simultaneously such that the total profit per unit time has a maximum value. An algorithm is developed to find the optimal solution, and numerical examples are provided to illustrate the theoretical results. A sensitivity analysis of the optimal solution with respect to major parameters is also carried out.[[incitationindex]]SCI[[booktype]]紙

    Optimal replenishment decisions under two-level trade credit with partial upstream trade credit linked to order quantity and limited storage capacity

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    [[abstract]]This paper extends the previous economic order quantity (EOQ) models under two-level trade credit such as Goyal (1985), Teng (2002), Huang (2003, 2007), Kreng and Tan (2010), Ouyang et al. (2013), and Teng et al. (2007) to reflect the real-life situations by incorporating the following concepts: (1) the storage capacity is limited, (2) the supplier offers the retailer a partially upstream trade credit linked to order quantity, and (3) both the dispensable assumptions that the upstream trade credit is longer than the downstream trade credit N<M and the interest charged per dollar per year is larger than or equal to the interest earned per dollar per year Ic<Ie are relaxed. We then study the necessary and sufficient conditions for finding the optimal solution for various cases and establish a useful algorithm to obtain the solution. Finally, numerical examples are given to illustrate the theoretical results and provide the managerial insights.[[notice]]補正完畢[[incitationindex]]SCI[[booktype]]紙本[[booktype]]電子

    An economic manufacturing quantity model for a two-stage assembly system with imperfect processes and variable production rate

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    [[abstract]]This article considers a two-stage assembly system with imperfect processes. The former is an automatic stage in which the required components are manufactured. The latter is a manual stage which deals with taking the components to assemble the end product. In addition, the component processes are independent of each other, and the assembly rate is variable. Shortage is allowed, and the unsatisfied demand is completely backlogged. Then, we formulate the proposed problem as a cost minimization model where the assembly rate and the production run time of each component process are decision variables. An algorithm for the computations of the optimal solutions under the constraint of assembly rate is also provided. Finally, a numerical example and sensitivity analysis are carried out to illustrate the model.[[notice]]補正完畢[[incitationindex]]SCI[[booktype]]紙

    Impacts of collaborative investment and inspection policies on the integrated inventory model with defective items

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    [[abstract]]For an imperfect production system, to reduce quality-related costs, a manager may consider investing capital in quality improvement. In general, the investment expense in reducing the defective rate of items is often paid by the vendor. On the other hand, the buyer may inspect the product quality as the order is received which implies it incurs an inspection cost. In a supply chain integrated system, to accomplish global optimisation, the vendor and buyer can agree to jointly invest capital to improve the imperfect production processes, and the buyer can remove the inspection programme as the defective rate reaches a certain low-level. Hence, this paper investigates the impacts of collaborative investment and inspection policies on an integrated inventory model with defective items. The objective of this study is to seek the optimal order quantity, shipping times from the vendor to the buyer per production run, and the defective rate that minimise the joint total cost per unit time. An algorithm is developed to find the optimal solution. Several numerical examples are presented to demonstrate the proposed model and solution procedure, and then several management insights are obtained from the numerical examples.[[incitationindex]]SCI[[incitationindex]]EI[[booktype]]紙

    Association analysis of monoamine oxidase A gene and bipolar affective disorder in Han Chinese

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    <p>Abstract</p> <p>Background</p> <p>Monoamine oxidase A (MAOA) is a mitochondrial enzyme involved in degrading several different biological amines, including serotonin. Although several pieces of evidence suggested that MAOA is important in the etiology of bipolar affective disorder (BPD), associations for markers of the MAOA gene with BPD were not conclusive and the association has not been investigated in Taiwanese population. This study was designed to illustrate the role of MAOA in the etiology of BPD in Han Chinese.</p> <p>Methods</p> <p>Two markers, a dinucleotide polymorphism in exon 2 and a functional uVNTR on the promoter of the <it>MAOA </it>gene, were used to study the genetic association in 108 unrelated patients with BPD and 103 healthy controls. Allelic distributions of two polymorphisms were analyzed and, caused the MAOA located at X chromosome, haplotype association was performed using haplotype unambiguously assigned in male participants.</p> <p>Results</p> <p>While no difference in allelic distributions of two MAOA polymorphisms was found, the risk haplotype 114S was associated with BPD in male patients (<it>P </it>= 0.03). The significance, however, was not found in female patients with 114S haplotype.</p> <p>Conclusion</p> <p>Results from this study suggest that MAOA may have a gender-specific and small effect on the etiology of BPD in Taiwan. Due to the limited sample size, results from this study need to be confirmed in replicates.</p

    Pelvic skeletal metastasis of hepatocellular carcinoma with sarcomatous change: a case report

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    Sarcomatoid hepatocellular carcinoma (HCC) is a very rare histologic variant of HCC. The characteristic of skeletal metastatic sarcomatoid hepatocellular carcinoma has never been reported. We reported a patient with sarcomatoid hepatocellular carcinoma pelvic metastasis who presented with huge pelvic metastasis that had relatively small osteolytic lesion centrally located accompanied by huge bipeduncular invasive expansile lesions into surrounding soft tissue. The lesion showed almost non-isotope uptake in 99mTc-methylene diphosphonate bone scintigraphy study. He underwent radiotherapy and tumor excision but the tumor rapidly recurred. In addition, serum α-fetoprotein level was never elevated beyond normal limit (< 20 ng/mL) through the whole course of treatment. We considered sarcomatoid hepatocellular carcinoma bone metastasis a highly aggressive lesion with unusual metastatic pattern. Surgical treatment with adequate safe margin in such a huge tumor with hypervascularity and extensive invasion in the pelvis was difficult; and radiotherapy maybe refractory regarding the sarcomatous nature. Therefore, debulking operation with local symptoms control may provide a better quality of life. And the clinical course suggests sarcomatoid hepatocellular carcinoma is derived from the transition of an ordinary hepatocellular carcinoma

    Cyclooxygenase-2 enhances α2β1 integrin expression and cell migration via EP1 dependent signaling pathway in human chondrosarcoma cells

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    <p>Abstract</p> <p>Background</p> <p>Cyclooxygenase (COX)-2, the inducible isoform of prostaglandin (PG) synthase, has been implicated in tumor metastasis. Interaction of COX-2 with its specific EP receptors on the surface of cancer cells has been reported to induce cancer invasion. However, the effects of COX-2 on migration activity in human chondrosarcoma cells are mostly unknown. In this study, we examined whether COX-2 and EP interaction are involved in metastasis of human chondrosarcoma.</p> <p>Results</p> <p>We found that over-expression of COX-2 or exogenous PGE<sub>2 </sub>increased the migration of human chondrosarcoma cells. We also found that human chondrosarcoma tissues and chondrosarcoma cell lines had significant expression of the COX-2 which was higher than that in normal cartilage. By using pharmacological inhibitors or activators or genetic inhibition by the EP receptors, we discovered that the EP1 receptor but not other PGE receptors is involved in PGE<sub>2</sub>-mediated cell migration and α2β1 integrin expression. Furthermore, we found that human chondrosarcoma tissues expressed a higher level of EP1 receptor than normal cartilage. PGE<sub>2</sub>-mediated migration and integrin up-regulation were attenuated by phospholipase C (PLC), protein kinase C (PKC) and c-Src inhibitor. Activation of the PLCβ, PKCα, c-Src and NF-κB signaling pathway after PGE<sub>2 </sub>treatment was demonstrated, and PGE<sub>2</sub>-induced expression of integrin and migration activity were inhibited by the specific inhibitor, siRNA and mutants of PLC, PKC, c-Src and NF-κB cascades.</p> <p>Conclusions</p> <p>Our results indicated that PGE<sub>2 </sub>enhances the migration of chondrosarcoma cells by increasing α2β1 integrin expression through the EP1/PLC/PKCα/c-Src/NF-κB signal transduction pathway.</p
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