Antenna pointing systematic error model derivations

The pointing model used to represent and correct systematic errors for the Deep Space Network (DSN) antennas is presented. Analytical expressions are given in both azimuth-elevation (az-el) and hour angle-declination (ha-dec) mounts for RF axis collimation error, encoder offset, nonorthogonality of axes, axis plane tilt, and structural flexure due to gravity loading. While the residual pointing errors (rms) after correction appear to be within the ten percent of the half-power beamwidth criterion commonly set for good pointing accuracy, the DSN has embarked on an extensive pointing improvement and modeling program aiming toward an order of magnitude higher pointing precision

Agricultural Communications Students Describe a Short-term Field Experience

Student-run publications, including newsrooms and similar agency-style work achieve the curricular goal of experiential learning (Roberts, 2006) for university agricultural communication students. Gaining a journalistic skillset in the classroom is richly supplemented with experiencing real-world and authentic agency immersion to reveal to students the genuine characteristics of a workplace. The purpose of this study was to use Q methodology to evaluate a real-world, out-of-class-but-supervised newsroom producing publications for the State FFA Convention. Fifteen undergraduate students who were immersed in this three-day program in which students publish original work to disseminate information to FFA participants and the public participated in the study at the end of the newsroom experience. With a concourse sampled along four dimensions of growth and development (Author, 2014), a Q set of 36 statements was sorted. In addition to the Q sorts, comments gathered from the students at the last session assisted in the interpretation of data. Post-sort interviews were conducted with exemplar sorters. Data were analyzed using principal components and varimax rotation and interpreted to show three ways the newsroom was experienced by the university students. The Supervisors honed managerial skills while working as colleagues with faculty supervisors. The Contented Staff valued the education gained from the experience and recognized the practical application of the communications-based skill-set. The Stressed Staff had insecurities and physical discomfort during the work and living in the city. Implications for program development, classroom instruction, and field experience assessment will be discussed

Shaped Pupil Lyot Coronagraphs: High-Contrast Solutions for Restricted Focal Planes

Coronagraphs of the apodized pupil and shaped pupil varieties use the Fraunhofer diffraction properties of amplitude masks to create regions of high contrast in the vicinity of a target star. Here we present a hybrid coronagraph architecture in which a binary, hard-edged shaped pupil mask replaces the gray, smooth apodizer of the apodized pupil Lyot coronagraph (APLC). For any contrast and bandwidth goal in this configuration, as long as the prescribed region of contrast is restricted to a finite area in the image, a shaped pupil is the apodizer with the highest transmission. We relate the starlight cancellation mechanism to that of the conventional APLC. We introduce a new class of solutions in which the amplitude profile of the Lyot stop, instead of being fixed as a padded replica of the telescope aperture, is jointly optimized with the apodizer. Finally, we describe shaped pupil Lyot coronagraph (SPLC) designs for the baseline architecture of the Wide-Field Infrared Survey Telescope-Astrophysics Focused Telescope Assets (WFIRST-AFTA) coronagraph. These SPLCs help to enable two scientific objectives of the WFIRST-AFTA mission: (1) broadband spectroscopy to characterize exoplanet atmospheres in reflected starlight and (2) debris disk imaging.Comment: 41 pages, 15 figures; published in the JATIS special section on WFIRST-AFTA coronagraph

The Influence of Aid and Income on Persistence at a Small Private College

In the 1990s, many private institutions gave up the practice of making need-blind admission decisions and stopped aiding students to the full extent of their need

Using Urban Farmer Perceptions of Urban Agricultural Resources to Inform Extension Programming: A Q Methodology Study

Urban farmers face challenges as they work among traditionally underserved populations, are new to farming, and may not recognize the resources available to them. The United States Department of Agriculture (USDA) prioritizes urban food production research and has recognized the unique challenges faced by urban farmers. The purpose of this study was to better understand the perspectives of urban farmers toward urban agricultural resources. Using the USDA Urban Agricultural Toolkit (2016) as a conceptual framework, this study found three perspectives of Oklahoma agricultural producers regarding urban agricultural resource challenges: The Visionary Farmer, The Business-minded Farmer, and The Learning Farmer. Visionary Farmers emphasize the application of urban agriculture toward urban social and community-building needs. Business-minded Farmers recognize the need for economic and financial education and resources for urban farmers. Learning Farmers highlight the need for continued agricultural education in urban agricultural operations. The findings suggest an opportunity for Extension and farmer-serving agencies to provide innovative communication, programming and support designed to address the unique struggles of urban farmers

Influence of structure on the optical limiting properties of nanotubes

We investigate the role of carbon nanotubes structure on their optical limiting properties. Samples of different and well-characterized structural features are studied by optical limiting and pump-probe experiments. The influence of the diameter's size on the nano-object is demonstrated. Indeed, both nucleation and growth of gas bubbles are expected to be sensitive to diameter

Operating and maintaining underground outlet terrace systems (1993)

The proper operation of underground outlet terrace systems depends on good farming practices, frequent inspections and prompt correction of problems. Inspect your systems soon after each significant rainfall. This is the best time to see existing or potential problems. Plainly marked inlets and outlets make this chore easy. Timely repairs or replacements normally lower maintenance costs, increase the life of the system and prevent serious problems

‘It will be hard because I will have to learn lots of English’: Experiences of education for children newly arrived in Australia

“This is an Accepted Manuscript of an article published by Taylor & Francis in [International Journal of Qualitative Studies in Education,] on [01 Jan 2015], available online: http:// www.tandfonline.com/10.1080/09518398.2015.1023232.”Educational experiences during childhood are critically important for development, but migrant children often experience unique challenges. To ameliorate these, extra training in English language - such as provided by the Intensive English language program in South Australia (IELP) - is frequently offered to children taking on English as an additional language (EAL). The present study aimed to examine the experience of transition into mainstream classes for children in the IELP, particularly in relation to their overall wellbeing. As such, the study utilised interviews conducted with newly arrived children in Australia aged five to 13 who were enrolled in an IELP, with interviews conducted both pre and post transition into mainstream primary school classes. The findings indicate that most children felt anxious prior to transition, especially regarding speaking English, but were less concerned about this once entering their new class. Making friends was considered to be difficult, but easier when there were children with whom they were familiar from other contexts, or if there was another child in the class with a shared cultural or linguistic background