Prism-based Method Research Articles

Fiber-based vortex beam source operating in a broadband or tunable mode

We demonstrate a fiber-based optical vortex beam source operating in broadband or tunable mode in the spectral range of 1100-1400 nm. The vector vortices of the total angular momenta equal to +2, 0, and -2 are obtained by converting the respective linearly polarized (LP11) modes of the two-mode birefringent PANDA fiber with stress-applying elements by gradually twisting its output section. At the input end, the PANDA fiber is powered by broadband supercontinuum or tunable Raman solitons generated in the LP11 polarization modes of a birefringent microstructured fiber with a specially designed dispersion profile and coupled to the respective LP11 modes of the PANDA fiber. Two pulse lasers operating in different regimes (1ns/1064 nm and 190 fs/1037 nm) were used as the pump to generate supercontinuum or tunable solitons directly in the LP11 modes of the microstructured fiber purely excited with a special Wollaston prism-based method. The high modal and polarization purities of the beams after successive transformations were experimentally confirmed. We also proved the vortex nature of the output beams using shearing interferometry.

Analysis of breathing via optoelectronic systems: comparison of four methods for computing breathing volumes and thoraco-abdominal motion pattern

Breathing parameters can be measured by motion capture systems by placing photo-reflective markers on the chest wall. A computational model is mandatory to compute the breathing volume and to calculate temporal and kinematical features by the gathered markers trajectories. Despite different methods based on different geometrical approaches can be adopted to compute volumes, no information about their differences in the respiratory evaluation are available. This study investigated the performances of four methods (conventional, prism-based, convex hull with boundary condition, based on Delaunay triangulation) using an optoelectronic motion capture system, on twelve healthy participants during 30 s of breathing. Temporal trends of volume traces, tidal volume values, and breathing durations were compared between methods and spirometry (used as reference instrument). Additionally, thoraco-abdominal motion patterns were compared between methods by analysing the compartmental contributions and their variability. Results shows comparable similarities between the volume traces obtained using spirometry, prism-based and conventional methods. Prism-based and convex hull with boundary condition methods show lower bias in tidal volumes estimation up to 0.06 L, compared to the conventional and Delaunay triangulation methods. Prism-based method shows maximum differences of 30 mL in the comparison of compartmental contributions to the total volume, by resulting in a maximum deviation of 1.6% in the percentage contribution analysis. In conclusion, our finding demonstrated the accuracy of the non-invasive MoCap-based breathing analysis with the prism-based method tested. Data provided in this study will lead researchers and clinicians in the computational method choice for temporal and volumetric breathing analysis.

A Novel Method to Compute Breathing Volumes via Motion Capture Systems: Design and Experimental Trials.

Respiratory assessment can be carried out by using motion capture systems. A geometrical model is mandatory in order to compute the breathing volume as a function of time from the markers' trajectories. This study describes a novel model to compute volume changes and calculate respiratory parameters by using a motion capture system. The novel method, ie, prism-based method, computes the volume enclosed within the chest by defining 82 prisms from the 89 markers attached to the subject chest. Volumes computed with this method are compared to spirometry volumes and to volumes computed by a conventional method based on the tetrahedron's decomposition of the chest wall and integrated in a commercial motion capture system. Eight healthy volunteers were enrolled and 30seconds of quiet breathing data collected from each of them. Results show a better agreement between volumes computed by the prism-based method and the spirometry (discrepancy of 2.23%, R 2 = .94) compared to the agreement between volumes computed by the conventional method and the spirometry (discrepancy of 3.56%, R 2 = .92). The proposed method also showed better performances in the calculation of respiratory parameters. Our findings open up prospects for the further use of the new method in the breathing assessment via motion capture systems.

Symbolic approach to verification and control of deterministic/probabilistic Boolean networks

A Boolean network (BN) is well known as one of the models of biological networks such as gene regulatory networks, and has been extensively studied. In this study, for a BN, the verification/control problems are discussed. First, a probabilistic model including both synchronous and asynchronous Boolean dynamics is derived. This model can be generalised as a probabilistic BN. Next, a solution method of the verification/control problems is proposed, based on a probabilistic model checker PRISM. Finally, the PRISM-based method is applied to an apoptosis network and a WNT5A network. The proposed approach provides us an easy and convenient tool for analysis and control of biological networks.

Total Internal Reflection Fluorescence Microscopy of Cell Adhesion on Patterned Self-Assembled Monolayers on Gold

We report the use of total internal reflection fluorescence microscopy (TIRFM) to study cell adhesion on patterned self-assembled monolayers (SAMs) on gold surfaces. Microcontact printing was used to pattern hydrophobic features to which the extracellular protein fibronectin was adsorbed, while dip-pen nanolithography was used to produce electroactive nanoarrays of hydroquinone-terminated alkanethiol on gold-coated quartz substrates. The hydroquinone was electrochemically oxidized to the corresponding quinone, and an oxyamine-tethered linear Arg-Gly-Asp (RGD) peptide was chemoselectively immobilized. A prism-based method of TIRFM was used to examine adhered cells on both the microscale and nanoscale features. We also demonstrate that, following imaging with TIRFM, the substrates can be visualized using conventional fluorescence microscopy.

Simple prism-based scheme for fabricating Bragg gratings in optical fibers

A modified prism-based method for fabricating Bragg gratings in optical fibers is introduced. We have made an optical fiber Bragg grating at 799.67 nm by using a 45 degrees right-angle prism and a frequency-doubled argon-ion laser at 244 nm. The advantage of this method is ease of alignment.

A trigonal prism-based method for hair image generation

The difficulties involved in modeling and rendering hair in computer graphics are described. An efficient method using a trigonal prism model to render individual human hairs is presented. A wisp model easily controls hair shape with a few parameters. The method also proves effective for rendering eyebrows, eyelashes, beards, moustaches, clothes and personal ornaments such as earrings and hair accessories. A double z-buffer generates the backlighting effect. A simple parabola approximates wisp loci for hair animation. The method makes it possible to draw an enormous number of hairs within a reasonably short time. >