Enhanced linear magneto-resistance near the Dirac point in topological insulator Bi2(Te1−xSex)3 nanowires

Nano Research - We report the composition and back-gate voltage tuned transport properties of ternary compound Bi2(Te1−xSex)3 nanowires synthesized by chemical vapor deposition (CVD). It is...     

Intelligent Handoff for Mobile Wireless Internet

This paper presents an intelligent mobility management scheme for Mobile Wireless InterNet – MWIN. MWIN is a wireless service networks wherein its core network consisting of Internet routers and its access network can be built from any Internet-capable radio network. Two major standards are currently available for MWIN, i.e., the mobile IP and wireless LAN. Mobile IP solves address mobility problem with the Internet protocol while wireless LAN provides a wireless Internet access in the local area. However, both schemes solve problems independently at different layers, thereby some additional problems occur, e.g., delayed handoff, packet loss, and inefficient routing. This paper identifies these new problems and performs analyses and some real measurements on the handoff within MWIN. Then, a new handoff architecture that extends the features of both mobile IP and wireless LAN handoff mechanism was proposed. This new architecture consists of mobile IP extensions and a modified wireless LAN handoff algorithm. The effect of this enhancement provides a linkage between different layers for preventing packet loss and reducing handoff latency. Finally, some optimization issues regarding network planning and routing are addressed.     

Design and synthesis of novel dual-action compounds targeting the adenosine A(2A) receptor and adenosine transporter for neuroprotection

A novel compound, N⁶‐(4‐hydroxybenzyl)adenosine, isolated from Gastrodia elata and which has been shown to be a potential therapeutic agent for preventing and treating neurodegenerative disease, was found to target both the adenosine A_2A receptor (A_2AR) and the equilibrative nucleoside transporter 1 (ENT1). As A_2AR and ENT1 are proximal in the synaptic crevice of striatum, where the mutant huntingtin aggregate is located, the dual‐action compounds that concomitantly target these two membrane proteins may be beneficial for the therapy of Huntington’s disease. To design the desired dual‐action compounds, pharmacophore models of the A_2AR agonists and the ENT1 inhibitors were constructed. Accordingly, potentially active compounds were designed and synthesized by chemical modification of adenosine, particularly at the N⁶ and C^5’ positions, if the predicted activity was within an acceptable range. Indeed, some of the designed compounds exhibit significant dual‐action properties toward both A_2AR and ENT1. Both pharmacophore models exhibit good statistical correlation between predicted and measured activities. In agreement with competitive ligand binding assay results, these compounds also prevent apoptosis in serum‐deprived PC12 cells, rendering a crucial function in neuroprotection and potential utility in the treatment of neurodegenerative diseases.     

Response of a Taipei Rapid Transit System (TRTS) tunnel to adjacent excavation

During the construction of the Taipei Rapid Transit System (TRTS) tunnels, a section of tunnel in the Panchiao Line was damaged as a result of adjacent excavation. Cracks appeared in reinforced concrete segments, the concrete slab on the invert was displaced and became detached from the segments. The event is a valuable case history for establishing criteria regulating excavations to be carried out adjacent to existing tunnels.     

Repair of displaced shield tunnel of the Taipei rapid transit system

A section of completed shield tunnel of the Panchiao Line of the Taipei Mass Rapid Transit (TRTS) was deformed and displaced due to an adjacent excavation. It was observed that the segments in the invert were separated from the concrete behind, and cracks were formed in the crown. In order to ensure that the shield tunnel section would meet the structural safety requirements set out by TRTS, the tunnel underwent repair work. This paper describes the damage, discusses the selection of repair methods, and outlines steel segment erection operations. It is the authors’ hope that the case presented would serve as a reference for other similar cases.     

QoS-aware,access-efficient,and storage-efficient replica placement in grid environments

In this paper, we study the quality-of-service (QoS)-aware replica placement problem in grid environments. Although there has been much work on the replica placement problem in parallel and distributed systems, most of them concern average system performance and have not addressed the important issue of quality of service requirement. In the very few existing work that takes QoS into consideration, a simplified replication model is assumed; therefore, their solution may not be applicable to real systems. In this paper, we propose a more realistic model for replica placement, which consider storage cost, update cost, and access cost of data replication, and also assumes that the capacity of each replica server is bounded. The QoS-aware replica placement is NP-complete even in the simple model. We propose two heuristic algorithms, called greedy remove and greedy add to approximate the optimal solution. Our extensive experiment results demonstrate that both greedy remove and greedy add find a near-optimal solution effectively and efficiently. Our algorithms can also adapt to various parallel and distributed environments.