Computing a Compact Spline Representation of the Medial Axis Transform of a 2D Shape

We present a full pipeline for computing the medial axis transform of an arbitrary 2D shape. The instability of the medial axis transform is overcome by a pruning algorithm guided by a user-defined Hausdorff distance threshold. The stable medial axis transform is then approximated by spline curves in 3D to produce a smooth and compact representation. These spline curves are computed by minimizing the approximation error between the input shape and the shape represented by the medial axis transform. Our results on various 2D shapes suggest that our method is practical and effective, and yields faithful and compact representations of medial axis transforms of 2D shapes.Comment: GMP14 (Geometric Modeling and Processing

Development of Non-Covalent Functionalization of Carbon Nanotubes for siRNA Delivery

RNA interference (RNAi) therapy is promising for treating various diseases but the delivery of small interfering RNA (siRNA) is difficult. To overcome the technical difficulties of siRNA delivery, an efficient and targeted delivery of siRNA is required for efficient RNAi therapy. Single-walled carbon nanotubes (CNT) has been used for nucleic acid delivery such as siRNA delivery. It has been found that CNT can gain entry into the cells by a diffusion-like mechanism which was called “nano-needle”. However, the solubility of CNT is low in most of the solvents including water. Functionalization of CNT can be carried out to enhance the solubility of the CNT in water and non-covalent functionalization of CNT is easy to be carried out. Poly(ethylenimine) (PEI) is a cationic polymer and it has been shown to disperse CNT in water. Also, it can deliver nucleic acids including siRNA. However, it is not very efficient at delivering siRNA unless adequately modified. Three different modifications on PEI were carried out. These polymers and the dispersed CNT were characterized and siRNA delivery capacities of the CNTs were examined in vitro and in vivo. The first was lipid-poly(ethylene glycol) (PEG) conjugated PEI. The second polymer was succinic acid conjugated PEI and the dispersed CNT was used topically in a melanoma model delivering Braf siRNA. The tumor progression was reduced dramatically. Following this work, folic acid, a ligand which target cancer cells was conjugated to the PEG and succinic acid modified PEI. The dispersed CNT was used for systematic delivery of mTOR siRNA in a melanoma model. The tumor progression was inhibited significantly

Learning Control Systems -Review and Outlook

The basic concept of learning control is introduced. The following four learning schemes are briefly reviewed: (l) trainable controllers using linear classifiers, (2) reinforcement learning control systems, (3) Bayesian estimation, and (J-i) stocha.stic approximation. Potential replications and problems for further research in learning control are outlined

Quantum Mechanical Noise in a Michelson Interferometer with Nonclassical Inputs: Nonperturbative Treatment

The variances of the quantum-mechanical noise in a two-input-port Michelson interferometer within the framework of the Loudon-Ni model were solved exactly in two general cases: (1) one coherent state input and one squeezed state input, and (2) two photon number states inputs. Low intensity limit, exponential decaying signal and the noise due to mixing were discussed briefly

A New Pre-authentication Scheme for IEEE 802.11i Wireless LAN Network

As 802.11 Wireless LAN network is vulnerable to many security attacks, a complicated authentication mechanism was developed in IEEE 802.11i to enhance the WLAN network security. Unfortunately, the original 802.11i authentication procedure takes some time to complete and it will significantly affect the quality of service offered to mobile users who may handover between several access points. The existing pre-authentication scheme can shorten the authentication time remarkably, but it suffers from the unnecessary signalling overhead which may be a heavy burden to the network. In this paper, we propose to improve the preauthentication mechanism via reducing the signalling overhead. In our scheme, the mobile user will initiate the pre-authentication with a neighbouring access point only when he is really approaching that particular access point. Therefore, many unnecessary preauthentication signalling overheads can be avoided. Preliminary simulation results show that signalling overhead can be reduced by 50% while still maintaining short authentication delay

A 3D-printed microfluidic-enabled hollow microneedle architecture for transdermal drug delivery.

Embedding microfluidic architectures with microneedles enables fluid management capabilities that present new degrees of freedom for transdermal drug delivery. To this end, fabrication schemes that can simultaneously create and integrate complex millimeter/centimeter-long microfluidic structures and micrometer-scale microneedle features are necessary. Accordingly, three-dimensional (3D) printing techniques are suitable candidates because they allow the rapid realization of customizable yet intricate microfluidic and microneedle features. However, previously reported 3D-printing approaches utilized costly instrumentation that lacked the desired versatility to print both features in a single step and the throughput to render components within distinct length-scales. Here, for the first time in literature, we devise a fabrication scheme to create hollow microneedles interfaced with microfluidic structures in a single step. Our method utilizes stereolithography 3D-printing and pushes its boundaries (achieving print resolutions below the full width half maximum laser spot size resolution) to create complex architectures with lower cost and higher print speed and throughput than previously reported methods. To demonstrate a potential application, a microfluidic-enabled microneedle architecture was printed to render hydrodynamic mixing and transdermal drug delivery within a single device. The presented architectures can be adopted in future biomedical devices to facilitate new modes of operations for transdermal drug delivery applications such as combinational therapy for preclinical testing of biologic treatments