Improved Cheeger's Inequality: Analysis of Spectral Partitioning Algorithms through Higher Order Spectral Gap

Let \phi(G) be the minimum conductance of an undirected graph G, and let 0=\lambda_1 <= \lambda_2 <=... <= \lambda_n <= 2 be the eigenvalues of the normalized Laplacian matrix of G. We prove that for any graph G and any k >= 2, \phi(G) = O(k) \lambda_2 / \sqrt{\lambda_k}, and this performance guarantee is achieved by the spectral partitioning algorithm. This improves Cheeger's inequality, and the bound is optimal up to a constant factor for any k. Our result shows that the spectral partitioning algorithm is a constant factor approximation algorithm for finding a sparse cut if \lambda_k$ is a constant for some constant k. This provides some theoretical justification to its empirical performance in image segmentation and clustering problems. We extend the analysis to other graph partitioning problems, including multi-way partition, balanced separator, and maximum cut

Retroperitoneal hemorrhage caused by enoxaparin-induced spontaneous lumbar artery bleeding and treated by transcatheter arterial embolization: a case report

Lumbar artery bleeding with retroperitoneal hematoma is an uncommon life-threatening complication secondary to enoxaparin use. We present a case of 73-year-old Chinese woman with acute retroperitoneal hemorrhage one month following hip surgery, due to enoxaparine. Enoxaparin induced hemorrhage caused by spontaneous rupture of lumbar artery was suspected and treated successfully by transcatheter arterial embolization

Evaluating the Operational Efficiency of Life Insurance Companies in Taiwan– An Application of the Dynamic Network SBM Model

Using a Dynamic Network Slack-based Measurement model (Tone & Tsutsui, 2014), this study evaluated the operational efficiency of life insurance firms in Taiwan from 2006 to 2013. In contrast to previous research, we incorporated assets and liabilities management into the model and compared them against optimal efficiency values in order to determine whether firms are earning maximizing profit while ensuring long-term solvency. The life insurance industry in Taiwan has matured. We found that market competitiveness depends on firms size and business model. Financial holdings companies and large corporations are performing strongly, while small local firms and foreign-owned firms scored poorly in technical efficiency. Economies of scale contribute to the business performance of life insurance firms. Life insurance companies that had merged with or been acquired by financial holdings firms showed notable improvement in efficiency. However, change in term efficiency is a warning signal in long-term business performance of life insurance firms. Lastly, most companies achieved optimal carry-over efficiency, indicating that they place considerable emphasis on managing assets and liabilities in order to ensure future solvency

Understanding Mobile Apps Continuance Usage Behavior and Habit: An Expectance-Confirmation Theory

With the growing development of information technology and the wireless telecommunication network nowadays, mobile devices have been expanding rapidly and have been emerging as important tools for consumers. Using m-services and applications (apps) on mobile devices becomes custom in people’s daily lives. This study proposes a theoretical model to explore the continued usage behavior for smartphone. The objective of this study is to explore how perceived usefulness, perceived enjoyment, and confirmation influencing satisfaction and habit of consumers, and in turn influencing continued usage behavior, as well as the moderating effect of three characteristics of m-commerce. The proposed model will empirically be tested using survey method and collecting data from smartphone users in longitudinal setting. The structural equation modeling technique will be used to evaluate the causal model and confirmatory factor analysis will be performed to examine the reliability and validity of the measurement model. The findings of this study are expected to illustrate how factors influence individuals to use m-services and mobile apps and become a habit, as well as how these habits influence continued smartphone usage

Pseudomonas aeruginosa sepsis with ecthyma gangrenosum and pseudomembranous pharyngolaryngitis in a 5-month-old boy

Pseudomonas aeruginosa infection that induced pseudomembranous laryngopharyngitis and ecthyma gangrenosum simultaneously in a healthy infant is rare. We reported on a previously healthy 5-month-old boy with initial presentation of fever and diarrhea followed by stridor and progressive respiratory distress. P. aeruginosa sepsis was suspected because ecthyma gangrenosum over the right leg was found at the emergency department, and the diagnosis was confirmed by the blood culture. Fiberscope revealed bacterial pharyngolaryngitis without involvement of the trachea. Because of early recognition and adequate treatment, including antimicrobial therapy, noninvasive ventilation, incision, and drainage, he recovered completely without any complications

Regulation of amino acid and nucleotide metabolism by crustacean hyperglycemic hormone in the muscle and hepatopancreas of the crayfish Procambarus clarkia.

To comprehensively characterize the metabolic roles of crustacean hyperglycemic hormone (CHH), metabolites in two CHH target tissues of the crayfish Procambarus clarkii, whose levels were significantly different between CHH knockdown and control (saline-treated) animals, were analyzed using bioinformatics tools provided by an on-line analysis suite (MetaboAnalyst). Analysis with Metabolic Pathway Analysis (MetPA) indicated that in the muscle Glyoxylate and dicarboxylate metabolism, Nicotinate and nicotinamide metabolism, Alanine, aspartate and glutamate metabolism, Pyruvate metabolism, and Nitrogen metabolism were significantly affected by silencing of CHH gene expression at 24 hours post injection (hpi), while only Nicotinate and nicotinamide metabolism remained significantly affected at 48 hpi. In the hepatopancreas, silencing of CHH gene expression significantly impacted, at 24 hpi, Pyruvate metabolism and Glycolysis or gluconeogenesis, and at 48 hpi, Glycine, serine and threonine metabolism. Moreover, analysis using Metabolite Set Enrichment Analysis (MSEA) showed that many metabolite sets were significantly affected in the muscle at 24hpi, including Ammonia recycling, Nicotinate and nicotinamide metabolism, Pyruvate metabolism, Purine metabolism, Warburg effect, Citric acid cycle, and metabolism of several amino acids, and at 48 hpi only Nicotinate and nicotinamide metabolism, Glycine and serine metabolism, and Ammonia recycling remained significantly affected. In the hepatopancreas, MSEA analysis showed that Fatty acid biosynthesis was significantly impacted at 24 hpi. Finally, in the muscle, levels of several amino acids decreased significantly, while those of 5 other amino acids or related compounds significantly increased in response to CHH gene silencing. Levels of metabolites related to nucleotide metabolism significantly decreased across the board at both time points. In the hepatopancreas, the effects were comparatively minor with only levels of thymine and urea being significantly decreased at 24 hpi. The combined results showed that the metabolic effects of silencing CHH gene expression were far more diverse than suggested by previous studies that emphasized on carbohydrate and energy metabolism. Based on the results, metabolic roles of CHH on the muscle and hepatopancreas are suggested: CHH promotes carbohydrate utilization in the hepatopancreas via stimulating glycolysis and lipolysis, while its stimulatory effect on nicotinate and nicotinamide metabolism plays a central role in coordinating metabolic activity in the muscle with diverse and wide-ranging consequences, including enhancing the fluxes of glycolysis, TCA cycle, and pentose phosphate pathway, leading to increased ATP supply and elevated protein and nucleic acid turnovers