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DNA can be used as a generic delivery vector in addition to its genetic role as a antigen expression vector. This is inspired in part by the fact that DNA molecules are true polymers. Surprisingly, DNA molecules have not been used as a delivery vector material. This is probably due to the fact that almost all DNA have only two shapes: linear or circular. This chapter details our efforts in fabricating highly branched dendrimer-like DNA (DL-DNA) that may serve as a multivalent DNA delivery vector. Just like chemical dendrimers, DL-DNA is multivalent and monodisperse. However, unlike traditional chemical dendrimers, DL-DNA is much larger (∼100 nm, generation 4) and can be designed to be nonsymmetric as well. Most importantly, DL-DNA possesses two unique properties: anisotropicity and biodegradability, making multiple, specific conjugations of viral peptides possible. Our method suggests that viral-peptide conjugated DL-DNA vectors can deliver genes into cells without any other transfection reagents. This viral-nonviral hybrid system can be further tailored to specific cells by conjugating specific ligands. We believe that such a DL-DNA-based, viral, and nonviral hybrid assembly will provide a new platform for drug delivery in general and gene delivery in particular. [ABSTRACT FROM AUTHOR]

Because moving objects usually moves on spatial networks, efficient trajectory index structures are required to gain good retrieval performance on their trajectories. However, there has been little research on trajectory index structure for spatial networks, like road networks. In this paper, we propose an efficient trajectory index structure for moving objects in Location-based Services (LBS). For this, we design our access scheme for efficiently dealing with the trajectories of moving objects on road networks. In addition, we provide both an insertion algorithm to store the initial information of moving object trajectories and one to store their segment information. We also provide a retrieval algorithm to find a set of moving objects whose trajectories match the segments of a query trajectory. Finally, we show that our trajectory access scheme achieves about one order of magnitude better retrieval performance than TB-tree. [ABSTRACT FROM AUTHOR]

The article presents a reprint of the article "The Roles of Image and Perceived Constraints at Different Stages in the Tourist's Destination Decision Process," by John L. Crompton published in a 1992 issue of the "Journal of Travel Research." It discusses the stages through which tourists pass in making a high involvement decision on which destination to visit. The sequential nature of the decision process is given. The roles played by image constraints at the stages in the decision process are provided. The challenges associated with undertaking longitudinal research are given.