2,789 research outputs found
Long-Run Purchasing Power Parity with Asymmetric Adjustment: Evidence from Mainland China and Taiwan
This study applies threshold cointegration test advanced by Enders and Siklos (2001) to investigate the properties of asymmetric adjustment in long-run purchasing power parity (PPP) for both Mainland China and Taiwan during the January 1986 to October 2009 period. Although there is evidence of long-run PPP for both Mainland China and Taiwan, the adjustment mechanism is asymmetric. These results have important policy implications for both Mainland China and Taiwan under study.threshold cointegration test; Purchasing Power Parity; asymmetric adjustment; Mainland China; Taiwan
Impact of the Casimir-Polder Potential and Johnson Noise on Bose-Einstein Condensate Stability near Surfaces
We investigate the stability of magnetically trapped atomic Bose-Einstein
condensates and thermal clouds near the transition temperature at small
distances 0.5 microns < d < 10 microns from a microfabricated silicon chip. For
a 2 microns thick copper film the trap lifetime is limited by Johnson-noise
induced currents and falls below 1 s at a distance of 4 microns. A dielectric
surface does not adversely affect the sample until the attractive
Casimir-Polder potential significantly reduces the trap depth.Comment: 4 pages, 5 figures, and submitted to Physical Review Letter
The Magnitude of Switching Costs for Corporate Antivirus Software Switching Decision
Today’s businesses environment is forcing companies to become increasingly more efficient in applying Internet technology to conduct transactions. AS the possibility of infection by computer virus is much greater now than ever before, businesses search for appropriate corporate antivirus software to safeguard their computer systems. This paper considers corporate antivirus software switching as one of the major security selection problem and proposes possible avenues for software switching decision and management.
In conceptual model, we draw upon switching costs where transaction costs, learning costs, and artificial costs were examined as main costs for software switching decision. Our findings shown only two out of three types of switching costs have influence over corporate antivirus software switching decisions. Despite the existence of switching costs, businesses continue to repeat software switching because the perceived risks of security threats are much greater than the switching cost itself. Furthermore, we examine various approaches to the cost of switching and then propose an index map to evaluate switching decision. Five sets of propositions are advanced to help guide this research
Experimental Study on Hydraulic Jumps with and Without Sediment
Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchive
Kernel Estimation of Rate Function for Recurrent Event Data
Recurrent event data are largely characterized by the rate function but smoothing techniques for estimating the rate function have never been rigorously developed or studied in statistical literature. This paper considers the moment and least squares methods for estimating the rate function from recurrent event data. With an independent censoring assumption on the recurrent event process, we study statistical properties of the proposed estimators and propose bootstrap procedures for the bandwidth selection and for the approximation of confidence intervals in the estimation of the occurrence rate function. It is identified that the moment method without resmoothing via a smaller bandwidth will produce curve with nicks occurring at the censoring times, whereas there is no such problem with the least squares method. Furthermore, the asymptotic variance of the least squares estimator is shown to be smaller under regularity conditions. However, in the implementation of the bootstrap procedures, the moment method is computationally more efficient than the least squares method because the former approach uses condensed bootstrap data. The performance of the proposed procedures is studied through Monte Carlo simulations and an epidemiological example on intravenous drug users
Histamine metabolism influences blood vessel branching in zebrafish reg6 mutants
<p>Abstract</p> <p>Background</p> <p>Vascular branching morphogenesis is responsible for the extension of blood vessels into growing tissues, a process crucial for organogenesis. However, the genetic mechanism for vessel branching is largely unknown. Zebrafish <it>reg6 </it>is a temperature-sensitive mutation exhibiting defects in blood vessel branching which results in the formation of swollen vessel lumina during capillary plexus formation.</p> <p>Results</p> <p>We performed a screening for chemical suppressors of <it>reg6 </it>and identified SKF91488, an inhibitor of histamine methyltransferase (HMT), that can rescue the <it>reg6 </it>vessel branching defects in a dose-dependent manner. Inhibition of HMT by SKF91488 presumably blocks histamine degradation, thus causing histamine accumulation. Consistent with this idea, we found that a high level of histamine also showed significant suppression of <it>reg6 </it>vessel phenotypes. Interestingly, when <it>reg6 </it>adults that had already developed swollen vessel lumina in regenerating fins were treated with histamine or SKF91488, either treatment significantly reduced the number of swollen vessels within 12 h, suggesting a rapid and constant influence of histamine on blood vessel branching. Furthermore, the expression of HMT was significantly elevated in <it>reg6 </it>regenerating fins. Conversely, lowering histamine by administering urocanic acid, a histidine decarboxylase inhibitor, enhanced the <it>reg6 </it>phenotypes. Finally, we identified that the transcription factor, egr-1 (early growth response factor 1), was closely associated with the <it>reg6 </it>phenotype and chemical treatments.</p> <p>Conclusion</p> <p>Taken together, our results suggest that blood vessel branching is influenced by histamine metabolism, possibly through regulating the expression of the egr-1 transcription factor.</p
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