How to Survive Dynamic Pricing Competition in E-commerce

ABSTRACT Pricing on e-commerce platforms is highly challenging. Sellers typically i) rival against dozens of competitors, ii) decide on prices for thousands of products, and iii) face steadily changing market situations. With respect to pricing, the challenge is to circumvent the curse of dimensionality to dynamically price products for a given market situation in a timely manner. In this project, we create a stochastic pricing model by analyzing recorded market data. This pricing model can be applied ad-hoc in less than a millisecond per item, allowing us to react immediately to new market situations. Our pricing approach is currently being applied in practice by a large German book seller on Amazon and outperforms the previous rule-based strategy by over 20% with respect to cash-in per book. CCS Concepts •Applied computing → Online shopping; E-commerce infrastructure; Decision analysis; Keywords Dynamic Pricing; Oligopoly Competition; Online Markets; Demand Estimation CHALLENGE Modern market platforms such as Amazon Marketplace or eBay are highly dynamic as sellers can observe the current market situation at any time and adjust their prices instantly. For sellers that handle large inventories, this dynamic is hard to manage as an optimal pricing decision requires handling a multitude of dimensions for each competitor (e.g., price, quality, shipping time, shipping costs, rating). Moreover, financial aspects such as discounting as well as inventory holding costs have to be taken into account. In this project, we partner with adanbo GmbH. adanbo is among the top 10 sellers for used books on Amazon in Germany with an inventory of over 80,000 distinct books (ISBN), each with multiple items (1-20). Our seller can decide -to some extent -on the replenishment of used books (by choosing purchase prices). However, supply is limited and it is not possible to directly reorder specific books. Hence, the challenge is to extract as much profit as pos- Copyright is held by the author(s). sible from a given number of books (inventory level) in a reasonable amount of time. The pricing strategy of our project partner is characterized by a rule-based system that has been developed over the past years by carefully adjusting rules to lessons learned from selling books on Amazon. As our project partner has more than 10 years of experience in the market, we consider his strategy to be effective and accurate. However, market dynamics are increasingly sophisticated making rule-based strategies increasingly hard to handle and maintain. Our goal is to develop a pricing strategy that maximizes expected discounted long-term profits while taking into account the constraints mentioned above. We seek to compute data-driven pricing strategies that are applicable even for large inventories. DATA-DRIVEN PRICING MODEL The project is devoted to revenue managemen

Fluoroscopy-guided jejunal extension tube placement through existing gastrostomy tubes: analysis of 391 procedures

PURPOSEWe aimed to evaluate the safety and efficacy of fluoroscopically placed jejunal extension tubes (J-arm) in patients with existing gastrostomy tubes.METHODSWe conducted a retrospective review of 391 J-arm placements performed in 174 patients. Indications for jejunal nutrition were aspiration risk (35%), pancreatitis (17%), gastroparesis (13%), gastric outlet obstruction (12%), and other (23%). Technical success, complications, malfunctions, and patency were assessed. Percutaneous gastrostomy (PEG) tube location, J-arm course, and fluoroscopy time were correlated with success/failure. Failure was defined as inability to exit the stomach. Procedure-related complications were defined as adverse events related to tube placement occurring within seven days. Tube malfunctions and aspiration events were recorded and assessed.RESULTSTechnical success was achieved in 91.9% (95% CI, 86.7%–95.2%) of new tubes versus 94.2% (95% CI, 86.7%–95.2%) of replacements (P = 0.373). Periprocedural complications occurred in three patients (0.8%). Malfunctions occurred in 197 patients (50%). Median tube patency was 103 days (95% CI, 71–134 days). No association was found between successful J-arm placement and gastric PEG tube position (P = 0.677), indication for jejunal nutrition (P = 0.349), J-arm trajectory in the stomach and incidence of malfunction (P = 0.365), risk of tube migration and PEG tube position (P = 0.173), or J-arm length (P = 0.987). A fluoroscopy time of 21.3 min was identified as a threshold for failure. Malfunctions occurred more often in tubes replaced after 90 days than in tubes replaced before 90 days (P < 0.001). A total of 42 aspiration events occurred (OR 6.4, P < 0.001, compared with nonmalfunctioning tubes).CONCLUSIONFluoroscopy-guided J-arm placement is safe for patients requiring jejunal nutrition. Tubes indwelling for longer than 90 days have higher rates of malfunction and aspiration

Transradial Access: A Comprehensive Review

Transradial access (TRA) via the left radial artery is an alternative to traditional transfemoral access for catheter-based procedures that is becoming increasingly more relevant in all types of arterial vascular interventions. First investigated in the realm of cardiology, TRA has been proven to provide many benefits (such as lower complication rates, lower cost, and improved patient comfort during and after the procedure) when compared with traditional femoral access while maintaining efficacy. This article provides an in-depth summary of the technical aspects of radial access while incorporating more recent data to explain patient preference for TRA, and the ways that TRA can improve peri-procedure workflow and compensation. It also describes potential complications, such as radial artery spasm, difficult anatomic variants and radial artery occlusion, and then gives techniques for mitigating and treating these complications. The article explains why TRA has become an important option for vascular and interventional radiology physicians, and why it is likely that this will continue to grow in relevance

Role for sphingosine kinase 1 in colon carcinogenesis

Sphingosine kinase 1 (SphK1) phosphorylates sphingosine to form sphingosine-1-phosphate (S1P) and is a critical regulator of sphingolipid-mediated functions. Cell-based studies suggest a tumor-promoting function for the SphK1/S1P pathway. Also, our previous studies implicated the SphK1/S1P pathway in the induction of the arachidonic acid cascade, a major inflammatory pathway involved in colon carcinogenesis. Therefore, we investigated whether the SphK1/S1P pathway is necessary for mediating carcinogenesis in vivo. Here, we report that 89% (42/47) of human colon cancer samples stained positively for SphK1, whereas normal colon mucosa had negative or weak staining. Adenomas had higher expression of SphK1 vs. normal mucosa, and colon cancers with metastasis had higher expression of SphK1 than those without metastasis. In the azoxymethane (AOM) murine model of colon cancer, SphK1 and S1P were significantly elevated in colon cancer tissues compared to normal mucosa. Moreover, blood levels of S1P were higher in mice with colon cancers than in those without cancers. Notably, SphK1−/− mice subjected to AOM had significantly less aberrant crypt foci (ACF) formation and significantly reduced colon cancer development. These results are the first in vivo evidence that the SphK1/S1P pathway contributes to colon carcinogenesis and that inhibition of this pathway is a potential target for chemoprevention.—Kawamori, T., Kaneshiro, T., Okumura, M., Maalouf, S., Uflacker, A., Bielawski, J., Hannun, Y. A., Obeid, L. M. Role for sphingosine kinase 1 in colon carcinogenesis