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

Performance of a Large-area GEM Detector Read Out with Wide Radial Zigzag Strips

A 1-meter-long trapezoidal Triple-GEM detector with wide readout strips was tested in hadron beams at the Fermilab Test Beam Facility in October 2013. The readout strips have a special zigzag geometry and run along the radial direction with an azimuthal pitch of 1.37 mrad to measure the azimuthal phi-coordinate of incident particles. The zigzag geometry of the readout reduces the required number of electronic channels by a factor of three compared to conventional straight readout strips while preserving good angular resolution. The average crosstalk between zigzag strips is measured to be an acceptable 5.5%. The detection efficiency of the detector is (98.4+-0.2)%. When the non-linearity of the zigzag-strip response is corrected with track information, the angular resolution is measured to be (193+-3) urad, which corresponds to 14% of the angular strip pitch. Multiple Coulomb scattering effects are fully taken into account in the data analysis with the help of a stand-alone Geant4 simulation that estimates interpolated track errors.Comment: 30 pages, 28 figures, submitted to NIM

A Field Note Describing the Development and Dissemination of Clear Language Research Summaries for University-Based Knowledge Mobilization

This field note places research summaries in the context of the knowledge mobilization literature and then describes the development, evaluation and dissemination of clear language research summaries as tools for research outreach, research communication and knowledge mobilization. The ResearchSnapshot clear language research summary format was developed with input from a Steering Committee comprised of academic and non-academic members. The research summary format was tested in roundtables of diverse research stakeholders and received positive feedback. The research summaries were then made accessible online and disseminated using a social media strategy. The use of twitter to enhance dissemination of the research summaries increased web traffic to the research summary database by 270%. This field note concludes with clear recommendations for individuals and organizations interested in developing their own clear language research summaries

Clear Language Summaries Are Tools for Research Outreach and Knowledge Mobilization

Research summaries employing clear language writing and design principles are able to engage a wider audience in university research. This allows for university research and research expertise to be accessible to community and government partners. Social media is also an important tool to attract non-academic readers online. These efforts create the potential for future research collaboration.York's Knowledge Mobilization Unit provides services and funding for faculty, graduate students, and community organizations seeking to maximize the impact of academic research and expertise on public policy, social programming, and professional practice. It is supported by SSHRC and CIHR grants, and by the Office of the Vice-President Research & Innovation. [email protected] www.researchimpact.c

Prevention and control of damage from wind erosion in cotton

Original authors: Bobby J. Phipps, State Extension Specialist-Cotton; Michael R. Milam, Regional Agronomy Specialis"Wind erosion and the damage it causes can affect cotton producers through reduced yields due to crop injury, the cost of replanting and the gradual loss of soil productivity. In extreme cases, blowing sand can reduce visibility and cause traffic hazards on roadways in affected areas. Wind erosion is common on loose, granular soils where large areas are unprotected. The motion and transport of sand particles in the wind depend on the size of the particles and on airflow. Soil particles that are lifted by the airflow and fall back again bounce along the soil surface in a process called saltation. Soil aggregates and larger particles that cannot be picked up by the wind tend to roll along the surface, pushed by the wind and the impact of other particles. This process is referred to as surface creep. Smaller grains that are held in suspension in the air may remain airborne and travel large distances before being washed from the air by rain."--First page.Reviewed by Bradley Wilson (Division of Plant Sciences), Bobby J. Phipps (State Extension Specialist-Cotton, University of Missouri Delta Center), Michael R. Milam (Regional Agronomy Specialist

Plasma generation and plume expansion for a transmission-mode microlaser ablation plasma thruster

An end-to-end model is presented of the transient plume created by a microlaser ablation plasma thruster. In this article, we describe a model of the plasma generation and expansion for a micro-laser plasma thruster operated in transmission-mode (T-mode). The laser ablation and plasma formation processes are modeled using a kinetic ablation model. This procedure provides boundary conditions at the target surface for the plume model that is based on a particle computational approach. The present study considers a 2.5–8 W diode-based laser irradiating a poly-vinyl chloride target for a pulse length of 3–10 ms. Laser beam shape full width at half maximum at the target is about 25×25 μm. The plume simulations reveal many details of the multicomponent plasma expansion. The results are compared with experimentally obtained plume signatures. Generally good agreement between experimental and calculated flux profiles is found. © 2004 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69665/2/JAPIAU-96-1-49-1.pd

Managing the Tensions at the Intersection of the Triple Bottom Line: A Paradox Theory Approach to Sustainability Management

Corporate sustainability management encompasses multiple dimensions: environmental, social, and economic. Companies are increasingly evaluated within the public sphere, and within their own organizations, according to the degree to which they are perceived to simultaneously promote this nexus of virtues. This article seeks to explore the tensions frequently faced by organizations that strive to manage these dimensions and the role of public policy in that pursuit. A multiple–case study approach is utilized in which the authors selected case organizations according to whether they were attempting to manage the three dimensions of sustainability. The authors utilize paradox theory and a typology provided by previous research to understand the nature of the tensions that emerge in the selected case study organizations. They extend this previous work by examining the role of public policy in providing the situational conditions to make these paradoxical tensions salient, and they examine organizational responses to these conditions. Directions for firms, policy makers, and future researchers are provided on the basis of this study’s findings

Prevalence and severity of dental caries among American Indian and Alaska Native preschool children

Objectives: To describe the Indian Health Service (IHS) oral health surveillance system and the oral health status of American Indian and Alaska Native (AI/AN) children aged 1‐5 years. Methods: A stratified probability sample of IHS/tribal sites was selected. Children were screened by trained examiners at community‐based locations including medical clinics, Head Start, preschools, kindergarten, and Women, Infants, and Children (WIC). Data collection was limited to the primary dentition and included number of teeth present plus number of teeth with cavitated lesions, restorations, and extracted because of decay. Number of molars with sealants and urgency of need for dental care data were also obtained. Statistical analyses were performed with SAS (SAS Institute Inc., Cary, NC, USA). Sample weights were used to produce population estimates based on selection probabilities. Results: A total of 8,461 AI/AN children 12‐71 months of age were screened at 63 IHS/tribal sites, approximately 7 percent of the estimated IHS user population of the same age. Overall, 54 percent of the children had decay experience, 39 percent had untreated decay, 7 percent had primary molar sealants, 36 percent needed early or urgent dental care, and 6 percent needed urgent dental care. The mean of decayed, missing, or filled teeth was 3.5 (95 percent confidence interval, 3.1‐3.9). The prevalence of decay experience increased with age; 21 percent of 1‐year‐olds and 75 percent of 5‐year‐olds had a history of caries. When stratified by IHS area, there were substantial differences in the oral health of preschool children. Conclusions: The results confirm that in the United States, AI/AN children served by IHS/tribal programs are one of the racial/ethnic groups at highest risk of caries.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/93514/1/j.1752-7325.2012.00331.x.pd

Managing the Tensions at the Intersection of the Triple Bottom Line: A Paradox Theory Approach to Sustainability Management

Corporate sustainability management encompasses multiple dimensions: environmental, social, and economic. Companies are increasingly evaluated within the public sphere, and within their own organizations, according to the degree to which they are perceived to simultaneously promote this nexus of virtues. This article seeks to explore the tensions frequently faced by organizations that strive to manage these dimensions and the role of public policy in that pursuit. A multiple–case study approach is utilized in which the authors selected case organizations according to whether they were attempting to manage the three dimensions of sustainability. The authors utilize paradox theory and a typology provided by previous research to understand the nature of the tensions that emerge in the selected case study organizations. They extend this previous work by examining the role of public policy in providing the situational conditions to make these paradoxical tensions salient, and they examine organizational responses to these conditions. Directions for firms, policy makers, and future researchers are provided on the basis of this study’s findings