891 research outputs found
Controlled Heterogeneous Nucleation and Growth of Germanium Quantum Dots on Nanopatterned Silicon Dioxide and Silicon Nitride Substrates
Controlled heterogeneous nucleation and growth of Ge quantum dots (QDs) are demonstrated on SiO_2/Si_3N_4 substrates by means of a novel fabrication process of thermally oxidizing nanopatterned SiGe layers. The otherwise random self-assembly process for QDs is shown to be strongly influenced by the nanopatterning in determining both the location and size of the QDs. Ostwald ripening processes are observed under further annealing at the oxidation temperature. Both nanopattern oxidation and Ostwald ripening offer additional mechanisms for lithography for controlling the size and placement of the QDs
Stationary Light Pulses in Cold Atomic Media
Stationary light pulses (SLPs), i.e., light pulses without motion, are formed
via the retrieval of stored probe pulses with two counter-propagating coupling
fields. We show that there exist non-negligible hybrid Raman excitations in
media of cold atoms that prohibit the SLP formation. We experimentally
demonstrate a method to suppress these Raman excitations and realize SLPs in
laser-cooled atoms. Our work opens the way to SLP studies in cold as well as in
stationary atoms and provides a new avenue to low-light-level nonlinear optics.Comment: 4 pages, 4 figure
A CMMI-based approach for medical software project life cycle study
In terms of medical techniques, Taiwan has gained international recognition in recent years. However, the medical information system industry in Taiwan is still at a developing stage compared with the software industries in other nations. In addition, systematic development processes are indispensable elements of software development. They can help developers increase their productivity and efficiency and also avoid unnecessary risks arising during the development process. Thus, this paper presents an application of Light-Weight Capability Maturity Model Integration (LW-CMMI) to Chang Gung Medical Research Project (CMRP) in the Nuclear medicine field. This application was intended to integrate user requirements, system design and testing of software development processes into three layers (Domain, Concept and Instance) model. Then, expressing in structural System Modeling Language (SysML) diagrams and converts part of the manual effort necessary for project management maintenance into computational effort, for example: (semi-) automatic delivery of traceability management. In this application, it supports establishing artifacts of “requirement specification document”, “project execution plan document”, “system design document” and “system test document”, and can deliver a prototype of lightweight project management tool on the Nuclear Medicine software project. The results of this application can be a reference for other medical institutions in developing medical information systems and support of project management to achieve the aim of patient safety. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/2193-1801-2-266) contains supplementary material, which is available to authorized users
Activation of Endothelial Cells by Antiphospholipid Antibodies—A Possible Mechanism Triggering Thrombosis in Patients with Antiphospholipid Syndrome
Antiphospholipid syndrome (APS) is an antibody-mediated hypercoagulable state characterized by recurrent venous and arterial thromboembolic events. The presence of serum antibodies are collectively termed as antiphospholipid antibodies (aPL) and is the hallmark of the disease. Interest in the pathogenesis has mostly been focused on the blood coagulation factor. However, endothelial cells might play an important role. When stimulated, cell membrane would flip to expose negatively charged phospholipids and activation markers such as adhesive molecules may appear. We consider that these changes may play an important role in the initiation of the thrombotic process when endothelial cells encounter aPL. In this study, we incubated human umbilical vein endothelial cells (HUVECs) with IgG isolated from patients with APS and found that the HUVECs were activated by the expression of negatively charged phospholipids, as shown by high annexin V binding and negative propidium iodide staining and by an increase in the level of intracellular cell adhesion molecule-1 on the cell surface. The above findings indicate that endothelial cells can be activated on exposure to aPL and trigger the thrombotic event
Planning and Implantation of NetFPGA Platform on Network Emulation Testbed
The concepts of cloud computing and Internet applications have expanded gradually and have become more and more important. Researchers need a new, high-speed network to build experimental environments for testing new network protocolswithout affecting existing traffic. In this paper, we describe a way to integrate NetFPGA platform, OpenFlow concept and NetFPGA reference designs into anetwork testbed to improve the packet processing speed and the dynamic adjustability for network emulation experiments. Furthermore, combined with Tunneling and VPLS, the proposed network testbed can be connected to distributed network, thus providing researchers a traffic-controllable and NIC-programmable experimental networking testbed in intra-communicating part
Toward Inter-Connection on OpenFlow Research Networks
With the advance of Future Internet technologies, many research issues andideas are growing fast in recent years. In the field of network virtualization, softwaredefined network becomes a common topic on network research. In Taiwan, manyinstitutes and laboratories of universities already built their bench-scale testbed forresearch and educational use with OpenFlow protocol. As time goes by, stitchingexperimental networks is a growing trend to fulfill requirements for large scaleemulation. Hence, this paper revealed a progressing deployment which connectsdifferent experimental networks with centralized control policy. The objective is tobuild an integrated research network with a proposed solution which utilizesOpenFlow protocol to deal with the inter-connections. With a centralized controllerand implemented architecture, the deployment not only solves the limitation of VLANtag number in network but also improves the flexibility of configuration. This designcould be a solution for the realistic constraints of network environment in Taiwan, andit also supports the possibility of stitching regional experimental networks fornetworking research
The Incremental Diagnostic Performance of Coronary Computed Tomography Angiography Added to Myocardial Perfusion Imaging in Patients with Intermediate-to-High Cardiovascular Risk
Purpose: Several studies have suggested that a combined approach of stress myocardial perfusion imaging (MPI) and coronary computed tomography angiography (CCTA) can provide diagnostic results with excellent accuracy. We aimed to explore whether the addition of CCTA to stress MPI provides incremental diagnostic value in intermediate-to-high cardiovascular risk patients. Methods: A total of 106 consecutive patients (93 male, 65 ± 10.4 years) underwent coronary artery calcium scoring (CACS), CCTA and 201 Thallium stress MPI before coronary angiography was reviewed. Thirty-seven patients (34.9%) had a history of proven coronary artery disease (CAD) or revascularization procedures, and four had documented non-significant CAD (3.8%). The remaining patients consisted of 17 (16.0%) classified as intermediate, and 48 (45.3%) as the high-risk groups. Results: Obstructive CAD was diagnosed by invasive coronary angiography in 88 patients with 161 vessels. The sensitivity and specificity in a patient-based analysis for obstructive CAD were 99% and 17% for CCTA, 80% and 50% for MPI and 91% and 67% for the combined method, respectively. The per-vessel diagnostic sensitivity and specificity were 95% and 54% for CCTA, 59% and 75% for MPI and 84% and 76% for the combined method. There were significant differences (p < 0.05) when comparing the combined method with MPI or CCTA by areas under the curve in a patient-or vessel-based analysis. However, CACS of 400 or more could not further stratify the patients with obstructive CAD. Conclusions: CCTA, not CACS, provided additional diagnostic values to stress MPI in patients with intermediateto-high cardiovascular risk
Early Warning System (EWS) of Currency Crises: An Empirical Study of Some SEACEN Countries
This paper investigates the macroeconomic factors in predicting the currency crises in a sample of 7 SEACEN countries using the logit econometric models. The empirical results indicate that the variables that may help predict the timing of the currency crises include real US interest rate, ratio of import to foreign reserves, real effective exchange rate, or money multiplier. In particular, the model that includes real US interest rate and ratio of import to foreign reserves can forecast better than other models for most of the 7 sample countries.
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