A Motion-aware Data Transfers Scheduling for Distributed Virtual Walkthrough Applications

Data transfers scheduling is an important part of almost all distributed virtual walkthrough (DVW) applications. Its main purpose is to preserve data transfer efficiency and render quality during scene exploration. The most limiting factors here are network restrictions such as low bandwidth and high latency. Current scheduling algorithms use multi-resolution data representation, priority determination and data prefetching algorithms to minimize these restrictions. Advanced priority determination and data prefetching methods for DVW applications use mathematic description of motion to predict next position of each individual user. These methods depend on the recent motion of a user so that they can accurately predict only near locations. In the case of sudden but regular changes in user motion direction (road networks) or fast moving user, these algorithms are not sufficient to predict future position with required accuracy and at required distances. In this paper we propose a systematic solution to scheduling of data transfer for DVW applications which uses next location prediction methods to compute download priority or additionally prefetch rendered data in advance. Experiments show that compared to motion functions the proposed scheduling scheme can increase data transfer efficiency and rendered image quality during scene exploration

Microfluidic chip for fast bioassays—evaluation of binding parameters

A seven channel polystyrene (PS) microchip has been constructed using a micromilling machine and a high-temperature assembling. Protein A (PA) has been immobilized by a passive sorption on the microchannel walls. Two bioaffinity assays with human immunoglobulin G (hIgG) as a ligand have been carried out. (i) PA as the receptor and fluorescently labeled hIgG (FITC-hIgG) as the ligand, (ii) PA as the receptor with hIgG as the quantified ligand and fluorescently labeled goat anti-human IgG (FITC-gIgG) as the secondary ligand. One incubation step of the assays took only 5 min instead of hours typical for enzyme-linked immunosorbent assay applications. Calibration curves of the dependence of a fluorescence signal on the hIgG concentration in a sample have been obtained in one step due to a parallel arrangement of microchannels. A mathematical model of the PA-FITC-hIgG complex formation in the chip has been developed. The values of the kinetic constant of the PA-FITC-hIgG binding (kon=5.5 m3 mol−1 s−1) and the equilibrium dissociation constant of the formed complex (Kd≤3×10−6 mol m−3) have been obtained by fitting to experimental data. The proposed microchip enables fast evaluation of kinetic and equilibrium constants of ligand-receptor bioaffinity pairs and the ligand quantification. As the use of microfluidic chips for immunoassays is often limited by price, we used procedures and chemicals that allow for an inexpensive construction and operation of the microdevice, e.g., temperature assembling as a fabrication technique, detection via an ordinary digital camera, nonspecific polystyrene as a substrate, passive sorption of biomolecules as an immobilization technique, etc