Removing Orbital Debris with Lasers

Orbital debris in low Earth orbit (LEO) are now sufficiently dense that the use of LEO space is threatened by runaway collisional cascading. A problem predicted more than thirty years ago, the threat from debris larger than about 1 cm demands serious attention. A promising proposed solution uses a high power pulsed laser system on the Earth to make plasma jets on the objects, slowing them slightly, and causing them to re-enter and burn up in the atmosphere. In this paper, we reassess this approach in light of recent advances in low-cost, light-weight modular design for large mirrors, calculations of laser-induced orbit changes and in design of repetitive, multi-kilojoule lasers, that build on inertial fusion research. These advances now suggest that laser orbital debris removal (LODR) is the most cost-effective way to mitigate the debris problem. No other solutions have been proposed that address the whole problem of large and small debris. A LODR system will have multiple uses beyond debris removal. International cooperation will be essential for building and operating such a system.Comment: 37 pages, 15 figures, in preparation for submission to Advances in Space Researc

A Study of a Mini-drift GEM Tracking Detector

A GEM tracking detector with an extended drift region has been studied as part of an effort to develop new tracking detectors for future experiments at RHIC and for the Electron Ion Collider that is being planned for BNL or JLAB. The detector consists of a triple GEM stack with a small drift region that was operated in a mini TPC type configuration. Both the position and arrival time of the charge deposited in the drift region were measured on the readout plane which allowed the reconstruction of a short vector for the track traversing the chamber. The resulting position and angle information from the vector could then be used to improve the position resolution of the detector for larger angle tracks, which deteriorates rapidly with increasing angle for conventional GEM tracking detectors using only charge centroid information. Two types of readout planes were studied. One was a COMPASS style readout plane with 400 micron pitch XY strips and the other consisted of 2x10mm2 chevron pads. The detector was studied in test beams at Fermilab and CERN, along with additional measurements in the lab, in order to determine its position and angular resolution for incident track angles up to 45 degrees. Several algorithms were studied for reconstructing the vector using the position and timing information in order to optimize the position and angular resolution of the detector for the different readout planes. Applications for large angle tracking detectors at RHIC and EIC are also discussed.Comment: Submitted to the IEEE Transactions on Nuclear Scienc

Carbon-Carbon Single Bond Activation for Nucleophilic Addition to Michael Acceptors

Intramolecular alkene carboacylation has previously been achieved under rhodium catalysis using quinolinyl ketones. Utilizing insight gained from mechanistic studies, new substrates containing ortho-substitution have been prepared and subjected to rhodium catalysis with an exogenous alkene. This research provides an overview of substrate synthesis as well as the unexpected product—rather than the anticipated carboacylation these substrates have been observed to undergo carbon-carbon bond activation followed by conjugate addition to Michael acceptors

Requiring Undergraduate Research for a BS Degree in Biology: Does It Do Any Good?

Cedarville University is a primarily undergraduate institution located in Southwest Ohio. Cedarville has always been committed to excellence in teaching, and our focus is on mentoring undergraduate students in order to ensure their future success. However, we realize that the research experience is a critical part of “learning science”. Several years ago, the biology faculty at Cedarville University decided to make a one-semester course in undergraduate research a mandatory component of the BS degree in biology. Research remains a popular elective choice for the BA degree in biology, as well as the biology education degree. Our aim in requiring research was twofold: 1. To help students learn the scientific method by putting it into practice while solving an original research problem. 2. To help students gain necessary marketable skills which would facilitate entry into either graduate/professional school or the industry position of their choice. Additional goals we had in mind included the following: • Inquiry-based learning • Learning new techniques • Learning the value of perseverance in research • Falsifying hypotheses • Working as a member of a tea

Risk-based verification of large offshore systems

This paper begins with a very brief review of the current status of offshore safety with particular reference to the UK sector. The risk-based verification concept is then described. Following identification of the research needs, a general risk-based verification framework is proposed with appropriate risk assessment contents incorporated into it. An example is then followed to demonstrate the proposed framework. The Health, Environment and Safety Information System (THESIS) software package is also used to facilitate the implementation of the framework. Finally, both the benefits and the limitations of risk-based verification in offshore applications are highlighted. The emphasis of the paper is focused on industrial applications

Chronicles of Oklahoma

Article recounts the story of how a band of thirteen men found and mined pure gold for years within a canyon in Oklahoma