2007 Farm Bill: Policy Options and Consequences for Northeast Specialty Crop Industries, Small Farms, and Sustainability. Report on Listening Sessions

Agricultural and Food Policy, Crop Production/Industries,

Control and Alignment of Segmented-Mirror Telescopes: Matrices, Modes, and Error Propagation

Starting from the successful Keck telescope design, we construct and analyze the control matrix for the active control system of the primary mirror of a generalized segmented-mirror telescope, with up to 1000 segments and including an alternative sensor geometry to the one used at Keck. In particular we examine the noise propagation of the matrix and its consequences for both seeing-limited and diffraction-limited observations. The associated problem of optical alignment of such a primary mirror is also analyzed in terms of the distinct but related matrices that govern this latter problem

What I believe about leadership and education : a reflective essay

Educational leadership means doing the right thing for the people we serve. It means being committed to the education of all the students. An educational leader needs to be a committed soul, passionate about creating success in the lives of every student. This is not an 8 a.m. to 4 p.m. or August to May commitment, it is 24 hours a day, 7 days a week and 365 days a year position. As an educator, this should be a career-long commitment. To help stay committed,an educational leader needs to develop core values that help one stay focused on the task at hand and guide one through troubled waters. To paraphrase Dr. G. Reed (public presentation, Fall, 2005), we either get better or worse, we never stay the same. We should seek to get better

Investigations in Post-fixation Physical Development

The procedure outlined by Matejec, Photograpische Korrespondenz, 104, 153 (1968), fixation in a thiosulfate-sulfite solution to which AgBr has been added, followed by washing in 1% sulfite solution, and development in a metol-sulfite-AgNO3 developer, was tested on seven silver iodobromide emulsions, each of a different average grain size. Samples were exposed, and processed by chemical and physical development. Matejec’s results, equality of threshold speed with post-fixation physical and chemical development, could only be realized with a very fine grain emulsion and high intensity exposure. It was found that the efficiency of physical development, relative to chemical development, is inversely related to grain size. The intensity of the exposing light was found to be an important factor which had large effects on the efficiency of physical development for the three emulsions tested. Samples of Kodak Spectroscopic Film, Types 103-0 and 103-F, were exposed by white light and developed in a time-temperature series, chemically and physically. The dye in the type F emulsion retarded post-fixation physical development and greatly increased fog, while decreasing gamma. A positive-type silver iodobromide emulsion dyed with 3,3\u27,9-triethyl-5,5\u27~dichlorothiacarbocyanine bromide was exposed by white and by blue light and processed chemically and physically. Development retardation was identified with chemical and post-fixation physical development. Contrast decreased and fog increased as the dye concentration approached 85% of monolayer coverage, for both chemical and physical development. However, fog was much more severe on the physically developed films. Matejec’s reported developer pH values were found to be in error. For better results, the solutions should be used as mixed, and not modified to pH 6, the value reported in the article. Sensitivity and fog suffer when the developer solutions are modified to pH 6. The color of the safelight used during the development step in physical development can have a significant effect on the fog density obtained when Matejec’s developer is used

Thoracic Pressure Does Not Impact CSF Pressure via Compartment Compliance

Space acquired neuro-ocular syndrome (SANS) remains a difficult risk to characterize due to the complex multi-factorial etiology related to physiological responses to the spaceflight environment. Fluid shift and the resultant change on the Cardiovascular (CV) and cerebral spinal fluid systems (CSF) in the absence of gravity continue to be considered a contributing factor to the progression of SANS. In this study, we utilize a computational model of the CSF and CV interface to establish the sensitivity that intracranial pressure, and subsequently the optic nerve sheath pressure, exhibits due to variations in thoracic pressure, assuming the cranial perfusion pressure, i.e. mean arterial pressure (MAP) to central venous pressure (CVP), is known. Methods: The GRC Cross cutting computational modeling project created as model of the CSF and CV interaction within the cranial vault by extending the work of Stevens et al. [1] by modifying the representative anatomy to include a separate venous sinus, jugular veins, secondary veins and extra jugular pathways [2-3] to more adequately represent the vascular drainage pathways from the cranial vault (Figure 1). Assuming the MAP, CVP and thoracic pressure are known, we initiated this enhanced computational model assuming a supine positon and utilized a linear ramp to vary the thoracic pressure from the assumed supine state to the target pressure corresponding to set MAP and CVP values. The model generates the time based CSF pressure values (Figure2). Results and Conclusions: Following this analysis, CSF pressure shows significant independence from thoracic pressure changes (16 mmHg in thoracic pressure produces < 1mmHg change in CSF pressure), being mostly dependent on perfusion pressure. Similarly fluid redistribution is not predicted to be impacted over a level of 1mL. We note that this simulation represents an acute changes (order of 10's of minutes) and does not represent the long term effects

Wind loads on ground-based telescopes

One of the factors that can influence the performance of large optical telescopes is the vibration of the telescope structure due to unsteady wind inside the telescope enclosure. Estimating the resulting degradation in image quality has been difficult because of the relatively poor understanding of the flow characteristics. Significant progress has recently been made, informed by measurements in existing observatories, wind-tunnel tests, and computational fluid dynamic analyses. We combine the information from these sources to summarize the relevant wind characteristics and enable a model of the dynamic wind loads on a telescope structure within an enclosure. The amplitude, temporal spectrum, and spatial distribution of wind disturbances are defined as a function of relevant design parameters, providing a significant improvement in our understanding of an important design issue

Phasing the Mirror Segments of the Keck Telescopes: The Broadband Phasing Algorithm

To achieve its full diffraction limit in the infrared, the primary mirror of the Keck telescope (now telescopes) must be properly phased: The steps or piston errors between the individual mirror segments must be reduced to less than 100 nm. We accomplish this with a wave optics variation of the Shack–Hartmann test, in which the signal is not the centroid but rather the degree of coherence of the individual subimages. Using filters with a variety of coherence lengths, we can capture segments with initial piston errors as large as ± 30 µm and reduce these to 30 nm—a dynamic range of 3 orders of magnitude. Segment aberrations contribute substantially to the residual errors of ~75 nm

The Effectiveness of Learning Geography Using Computer-based Games

Eighty, seventh grade students attending a suburban middle school in southern Connecticut participated in the study evaluating the effectiveness of computer based geography games on student motivation and achievement. Using Connecticut Mastery Test (CMT) Scores and baseline U.S.A scores as criteria to develop matched pairs, students were divided so that the control group played Sheppardsoftware.com’s States Level 3 and the experimental group played States Level 6. According to the data collected, States Level 3 and States Level 6 are significantly effective instructional tools that students enjoyed playing. CMT scores in spatial reasoning did not prove strong predictors of students’ performance whereas U.S.A. baseline testing was a strong indicator in two of three categories. Results support the use of computer-based games to increase student motivation and social studies achievement

Design considerations for CELT adaptive optics

California Institute of Technology and University of California have begun conceptual design studies for a new telescope for astronomical research at visible and infrared wavelengths. The California Extremely Large Telescope (CELT) is currently envisioned as a filled-aperture, steerable, segmented telescope of approximately 30 m diameter. The key to satisfying many of the science goals of this observatory is the availability of diffraction-limited wavefront control. We describe potential observing modes of CELT, including a discussion of the several major outstanding AO system architectural design issues to be resolved prior to the initiation of the detailed design of the adaptive optics capability