Comparing the use of meat and clay during cutting and projectile research

Diverse disciplines investigate how muscular tissue (i.e. ‘meat’) responds to being cut and deformed, however, large-scale, empirically robust investigations into these matters are often impractical and expensive. Previous research has used clay as an alternative to meat. To establish whether clay is a reliable proxy for meat, we directly compare the two materials via a series of cutting and projectile tests. Results confirm that the two materials display distinct cutting mechanics, resistance to penetration and are not comparable. Under certain conditions clay can be used as an alternative to meat, although distinctions between the two may lead to experimental limitations

The James Webb Space Telescope Mission: Optical Telescope Element Design, Development, and Performance

The James Webb Space Telescope (JWST) is a large, infrared space telescope that has recently started its science program which will enable breakthroughs in astrophysics and planetary science. Notably, JWST will provide the very first observations of the earliest luminous objects in the Universe and start a new era of exoplanet atmospheric characterization. This transformative science is enabled by a 6.6 m telescope that is passively cooled with a 5-layer sunshield. The primary mirror is comprised of 18 controllable, low areal density hexagonal segments, that were aligned and phased relative to each other in orbit using innovative image-based wavefront sensing and control algorithms. This revolutionary telescope took more than two decades to develop with a widely distributed team across engineering disciplines. We present an overview of the telescope requirements, architecture, development, superb on-orbit performance, and lessons learned. JWST successfully demonstrates a segmented aperture space telescope and establishes a path to building even larger space telescopes.Comment: accepted by PASP for JWST Overview Special Issue; 34 pages, 25 figure

The James Webb Space Telescope Mission

Twenty-six years ago a small committee report, building on earlier studies, expounded a compelling and poetic vision for the future of astronomy, calling for an infrared-optimized space telescope with an aperture of at least $4m$. With the support of their governments in the US, Europe, and Canada, 20,000 people realized that vision as the $6.5m$ James Webb Space Telescope. A generation of astronomers will celebrate their accomplishments for the life of the mission, potentially as long as 20 years, and beyond. This report and the scientific discoveries that follow are extended thank-you notes to the 20,000 team members. The telescope is working perfectly, with much better image quality than expected. In this and accompanying papers, we give a brief history, describe the observatory, outline its objectives and current observing program, and discuss the inventions and people who made it possible. We cite detailed reports on the design and the measured performance on orbit.Comment: Accepted by PASP for the special issue on The James Webb Space Telescope Overview, 29 pages, 4 figure

A Critical Study of the Circuit Concept

From Maxwell's equations, an expression for the complex power associated with a wire circuit is formulated and broken into a complex input power and a complex power into the external fields associated with the circuit, the latter including the radiated power. From these powers, the internal and external impedances of the circuit are obtained such that the current is not required to be everywhere in time phase within the circuit. This concept is extended to coupled circuits, bringing out some of the relations between some conventional methods for obtaining the driving point impedance of antenna arrays. The theory does not require the current distributions to be postulated, but in practical applications such a postulate becomes necessary unless the solution is obtained by a method such as the integral equation method. The resulting circuitry may readily be reduced to that for lumped elements. A more critical study of the impedance formulas is given in the appendix, based upon the reciprocity theorem which is derived therein

Translating an Existing Scientific Application from C to Dataparallel C

This report describes the translation of an existing sequential scientific program written the C programming language into the parallel programming language Dataparallel C. The resulting Dataparallel C program is able to use a network of workstations as though it were a single highperformance parallel computer. We describe the amount of effort required to translate the existing scientific program and the timing results of the translated program are compared to the sequential program. We conclude with some recommendations to parallel programming language designers, implementors of parallel programming languages, and application programmers

Using Hypertext to Facilitate Information Sharing in Biomedical Research Groups

In many areas of work, task complexity often demands that highly integrated groups carry projects forward. These teams must often solve difficult problems of task coordination and information integration, so deficiencies in information management limit the progress they may achieve. Advanced information technology, with its enormous capabilities for transmittin