A Novel Index Portefolio Model by Minimizing the Absolute Tracking Error -- Empirical Stusies in the Taiwan Stock Market

The index portfolio model attempts to form a portfolio whose time series in the market can trace the selected index as much as possible. The traditional index portfolio model, estimated coefficients models proposed by Salkin, established the portfolio by minimizing the square tracking error. In this paper, a novel index portfolio model formed by minimizing the absolute tracking error is proposed. In addition to preserving the characteristics of Salkin’s model, the proposed model can guarantee obtaining the global optimum solution and, in contrast to Salkin’s model, it can avoid the effect of the extreme value, which Salkin’s model may not. Also in contrast to the traditional model, the proposed one is a linear programming model and can then include practical constraints in the models, including the transaction cost constraints and limited stock catalog constraints. How the improved models address these constraints would be discussed as well. Moreover, different empirical studies in the Taiwan Stock Market are provided to demonstrate the proposed model’s effectivenes

Asian Primate Species Richness Correlates with Rainfall

Previous studies of meta-analyses found significantly positive correlations between primate species richness and rainfall for Africa, Madagascar and the Neotropics, with the exception of Asia, leaving the open question whether that anomaly is the result of sampling bias, biogeography, or some other factor. This study re-examines the question using modelled data, with primate species richness data from the Southeast Asian Mammals Databank and rainfall data from the Climatic Research Unit. Data processing with Geographical Information Systems resulted in 390 sample points. Reduced major axis and ordinary least squares regressions were employed to examine the relationship for six regions, including the whole study area of Southeast Asia, and the subareas of Huxley West, Huxley East, Mainland Southeast Asia, Borneo, and Sumatra. The results showed a significant positive relationship between primate species richness and mean annual rainfall for Southeast Asia (r = 0.26, P,0.001). Comparing the results for the large islands and Mainland Southeast Asia showed that Sumatra had the highest correlation (r = 0.58; P,0.05). After controlling for the major biogeographic effect associated with Huxley’s Line, our results showed that primate species richness is positively associated with mean annual rainfall in Southeast Asia. Our findings contrast to prior studies of meta-analyses that showed no relationship between rainfall and primate species richness in Asia, and thereby bring Asia into agreement with results showing significant positive correlations between rainfall and primate species richness everywhere else in the world. The inference is that previous anomalous results for Asia were result of sampling bias in the meta-analysis

The effects of rapid urbanization on forest landscape connectivity in Zhuhai city, China

Urban forests can provide the necessary ecosystem services for their residents and play an important part in improving the urban environment. Forest landscape connectivity is a vital indicator reflecting the quality of the ecological environment and ecological functions. Detecting changes in landscape connectivity is, therefore, an important step for providing sound scientific evidence for the better urban planning. Using remote sensing images of a study area in Zhuhai City in 1999, 2005, 2009 and 2013, the dynamic forest landscape connectivity of Zhuhai city can be evaluated based on a graph-theoretic approach. The aims of our study were to discover and interpret the effect of rapid urbanization on forest landscape connectivity. The construction of ecological corridors helps us specifically compare the landscape connectivity of three parts of urban forests. On the basis of functional landscape metrics, the correlation of these metrics and patch area was discussed in order to comprehensively identify the key patches. The analysis showed that the total areas of forestlands reduced from 1999 to 2009 and then increased from 2009 to 2013, and the same trend was found in overall forest landscape connectivity. To improve the overall landscape connectivity, construct urban ecological network and appropriately protect biodiversity in the future, the existing important patches with large areas or key positions should be well protected. This study revealed that urbanization reduced the area of key patches and consequently reduced the forest landscape connectivity, which increased while the patch areas increased due to the environmental protection policy. Functional connectivity indicators could provide more comprehensive information in the development of environmental protection strategies

T Oligo-Primed Polymerase Chain Reaction (TOP-PCR): A Robust Method for the Amplification of Minute DNA Fragments in Body Fluids.

Body fluid DNA sequencing is a powerful noninvasive approach for the diagnosis of genetic defects, infectious agents and diseases. The success relies on the quantity and quality of the DNA samples. However, numerous clinical samples are either at low quantity or of poor quality due to various reasons. To overcome these problems, we have developed T oligo-primed polymerase chain reaction (TOP-PCR) for full-length nonselective amplification of minute quantity of DNA fragments. TOP-PCR adopts homogeneous "half adaptor" (HA), generated by annealing P oligo (carrying a phosphate group at the 5' end) and T oligo (carrying a T-tail at the 3' end), for efficient ligation to target DNA and subsequent PCR amplification primed by the T oligo alone. Using DNA samples from body fluids, we demonstrate that TOP-PCR recovers minute DNA fragments and maintains the DNA size profile, while enhancing the major molecular populations. Our results also showed that TOP-PCR is a superior method for detecting apoptosis and outperforms the method adopted by Illumina for DNA amplification

A Parallel Thrombolysis Protocol with Nurse Practitioners As Coordinators Minimized Door-to-Needle Time for Acute Ischemic Stroke

Introduction. Quick thrombolysis after stroke improved clinical outcomes. The study objective was to shorten door-to-needle time for thrombolysis. Methods. After identifying the sources of in-hospital delays, we developed a protocol with a parallel algorithm and recruited nurse practitioners into the acute stroke team. We applied the new protocol on stroke patients from October 2009 to September 2010. Patients from the previous two years were used for comparison. Results. For ischemic stroke patients within 3 hours of onset, the median time from arrival to computed tomography scanning was reduced from 29 to 20 minutes (P < 0.001) and the median time from arrival to neurology evaluation decreased from 61 to 43 minutes (P < 0.001). For those patients who received thrombolysis, the median door-to-needle time was shortened from 68.5 to 58 minutes (P < 0.05). Conclusions. The parallel thrombolysis protocol successfully improved the median door-to-needle time to below the guideline-recommended 60 minutes

Changes in transcriptional orientation are associated with increases in evolutionary rates of enterobacterial genes

<p>Abstract</p> <p>Background</p> <p>Changes in transcriptional orientation (“CTOs”) occur frequently in prokaryotic genomes. Such changes usually result from genomic inversions, which may cause a conflict between the directions of replication and transcription and an increase in mutation rate. However, CTOs do not always lead to the replication-transcription confrontation. Furthermore, CTOs may cause deleterious disruptions of operon structure and/or gene regulations. The currently existing CTOs may indicate relaxation of selection pressure. Therefore, it is of interest to investigate whether CTOs have an independent effect on the evolutionary rates of the affected genes, and whether these genes are subject to any type of selection pressure in prokaryotes.</p> <p>Methods</p> <p>Three closely related enterbacteria, <it>Escherichia coli</it>, <it>Klebsiella pneumoniae</it> and <it>Salmonella enterica serovar Typhimurium</it>, were selected for comparisons of synonymous (<it>dS</it>) and nonsynonymous (<it>dN</it>) substitution rate between the genes that have experienced changes in transcriptional orientation (changed-orientation genes, “COGs”) and those that do not (same-orientation genes, “SOGs”). The <it>dN</it>/<it>dS</it> ratio was also derived to evaluate the selection pressure on the analyzed genes. Confounding factors in the estimation of evolutionary rates, such as gene essentiality, gene expression level, replication-transcription confrontation, and decreased <it>dS</it> at gene terminals were controlled in the COG-SOG comparisons.</p> <p>Results</p> <p>We demonstrate that COGs have significantly higher <it>dN</it> and <it>dS</it> than SOGs when a series of confounding factors are controlled. However, the <it>dN</it>/<it>dS</it> ratios are similar between the two gene groups, suggesting that the increase in <it>dS</it> can sufficiently explain the increase in <it>dN</it> in COGs. Therefore, the increases in evolutionary rates in COGs may be mainly mutation-driven.</p> <p>Conclusions</p> <p>Here we show that CTOs can increase the evolutionary rates of the affected genes. This effect is independent of the replication-transcription confrontation, which is suggested to be the major cause of inversion-associated evolutionary rate increases. The real cause of such evolutionary rate increases remains unclear but is worth further explorations.</p

Using Rare Earth Elements to Constrain Particulate Organic Carbon Flux in the East China Sea

Fluxes of particulate organic carbon (POC) in the East China Sea (ECS) have been reported to decrease from the inner continental shelf towards the outer continental shelf. Recent research has shown that POC fluxes in the ECS may be overestimated due to active sediment resuspension. To better characterize the effect of sediment resuspension on particle fluxes in the ECS, rare earth elements (REEs) and organic carbon (OC) were used in separate two-member mixing models to evaluate trap-collected POC fluxes. The ratio of resuspended particles from sediments to total trap-collected particles in the ECS ranged from 82-94% using the OC mixing model, and 30-80% using the REEs mixing model, respectively. These results suggest that REEs may be better proxies for sediment resuspension than OC in high turbidity marginal seas because REEs do not appear to undergo degradation during particle sinking as compared to organic carbon. Our results suggest that REEs can be used as tracers to provide quantitative estimates of POC fluxes in marginal sea

Composite type A thymoma and diffuse large B-cell lymphoma

AbstractThe concurrent occurrence of thymoma and diffuse large B-cell lymphoma in the thymus has not been previously reported. We describe a 74-year-old man who presented with general weakness, neck lymphadenopathy, night sweats, and body weight loss. A right anterior mediastinal mass was found on computed tomography of the chest. The immunohistochemical stains AE1/AE3, CD20, CD3, and MUM-1 confirmed the different components of the mediastinal tumor. A heavy-chain gene clonality assay and light-chain gene clonality assay confirmed the B-cell clonality of the mediastinal tumor and neck lymph node. The patient had received a complete course of chemotherapy, and the result of positron emission tomography–computed tomography showed complete remission. The pathologic report of this mass revealed composite type A thymoma and diffuse large B-cell lymphoma. If concurrent or composite thymoma and lymphoma are suspected, a thorough examination of the thymoma with a combination of ancillary studies is recommended to rule out the possibility of concurrent lymphoma