Particle-In-Cell (PIC) codes are often used to study systems where the details of phasespace are important; for example, self trapping or optical injection in laser-plasma accelerators. Here we investigate the numerical heating and macro-particle trajectory errors in 2D PIC simulations of laser-plasma accelerators. The effects of grid resolution and laser polarization on the momentum spread and...

UNLABELLED Silica grids with micron to sub-micron mesh sizes and wire diameters of 50 nm are fabricated on fused silica substrates. They are formed by single-pulse structured excimer laser irradiation of a UV-absorbing silicon suboxide (SiOx) coating through the transparent substrate. A polydimethylsiloxane (PDMS) superstrate (cover layer) coated on top of the SiOx film prior to laser exposure ...

The need for accurate geometric and radiometric information over large areas has become increasingly important. Laser altimetry is one of the key technologies for obtaining this geometric information. However, there are important application areas where the observing platform has its orbit constrained by the other instruments it is carrying, and so the spatial resolution that can be recorded by...

We describe a simple way to generate a wide-area high-resolution focus grid by in-line holography and study the factors that impacts its quality. In our holographic recording setup, the reference beam was the direct transmission of the incoming collimated laser beam through a mask coating with thin metal film, and the sample beam was the transmission of the laser through small apertures fabrica...

This paper describes a new method for determining corneal surface detail utilizing a modified Zeiss photo slit lamp. This system projects a grid onto the cornea through a cobalt blue filter. The tear film is stained with fluorescein, causing the projected grid pattern to be visible on the corneal surface. A video image of the grid is then digitized by an image processor which calculates surface...

Purpose Current perimeters use fixed grid patterns. We test whether a grid based on an individual's retinal nerve fiber layer (RNFL) thickness profile would find more visual field (VF) defects. Methods We describe the defect-based method for choosing test locations. First, the 26 VF locations with the highest positive predictive value to detect glaucoma from the 24-2 pattern are chosen. An ad...

We report on the formation of organized sub-micron YBa(2)Cu(3)O(7) (YBCO) dots induced by irradiating femtosecond laser pulses on YBCO films prepared by pulse laser deposition with fluence in the range of 0.21 approximately 0.53 J/cm(2). The morphology of the YBCO film surface depends strongly on the laser fluences irradiated. At lower laser fluence (approximately 0.21 J/cm(2)) the morphology w...

Neurons in the medial entorhinal cortex fire action potentials at regular spatial intervals, creating a striking grid-like pattern of spike rates spanning the whole environment of a navigating animal. This remarkable spatial code may represent a neural map for path integration. Recent advances using patch-clamp recordings from entorhinal cortex neurons in vitro and in vivo have revealed how the...

In this paper, we present a three-dimensional mapping system for mobile robots using laser range sensors. Our system provides sensor preprocessing, efficient local mapping for reliable obstacle perception, and allocentric mapping with real-time localization for autonomous navigation. The software is available as open-source ROS-based package and has been successfully employed on different robot...

Estimating and keeping track of the distance from salient points of the environment are important constituents of the spatial awareness and navigation. In rodents, the majority of principal cells in the hippocampus are known to be correlated with the position of the animal. However, the lack of topography in the hippocampal cognitive map does not support the assumption that connections between ...