A Fast Algorithm for Well-Spaced Points and Approximate Delaunay Graphs

We present a new algorithm that produces a well-spaced superset of points conforming to a given input set in any dimension with guaranteed optimal output size. We also provide an approximate Delaunay graph on the output points. Our algorithm runs in expected time $O(2^{O(d)}(n\log n + m))$, where $n$ is the input size, $m$ is the output point set size, and $d$ is the ambient dimension. The constants only depend on the desired element quality bounds. To gain this new efficiency, the algorithm approximately maintains the Voronoi diagram of the current set of points by storing a superset of the Delaunay neighbors of each point. By retaining quality of the Voronoi diagram and avoiding the storage of the full Voronoi diagram, a simple exponential dependence on $d$ is obtained in the running time. Thus, if one only wants the approximate neighbors structure of a refined Delaunay mesh conforming to a set of input points, the algorithm will return a size $2^{O(d)}m$ graph in $2^{O(d)}(n\log n + m)$ expected time. If $m$ is superlinear in $n$, then we can produce a hierarchically well-spaced superset of size $2^{O(d)}n$ in $2^{O(d)}n\log n$ expected time.Comment: Full versio

Market egg production in New England.

Thesis (M.A.)--Boston UniversityThis paper is an attempt to point out and explain the character of the egg producing industry in New England. In recent years this phase of the poultry industry has gained increasing prominence in the New England area. Data gleaned from census reports, United States Department of Agriculture publications, and studies made by the various: New England Agricultural Experiment Stations and Extension Services have been used liberally throughout the body of the paper. [TRUNCATED

Adaptive Optics: introduction to the feature issue

This Applied Optics feature issue is a companion to the Journal of the Optical Society of America A feature issue on the same topic. The feature highlights the expansion of adaptive optics to different applications as well as its development to routine applications brought about because of significant advances in component technologies

THE U.S. DAIRY INDUSTRY

Agribusiness,

Trickle Down Engagement in First-Year Common Reading Programs

Common reading programs provide first-year students with common experiences that facilitate their engagement in the academic and social domains of college life. We investigated how the levels of engagement in common reading programs (e.g., recommended the book to students) by individuals in academic support roles (e.g., instructors, advisors, student life personnel) predicted students’ engagement in the book and book-related activities, as well as students’ retention of book content. We will discuss the importance of trickle down engagement (e.g., from instructors to students) in the success of common reading programs and offer practical recommendations to increase engagement in common reading programs.Citation: Coleman, T., Saucier, D., & Miller, S. Trickle down engagement in first-year common reading programs. Paper submitted to the 35th Annual Conference on the First-Year Experience, Orlando, FL

Determinants of Agricultural Landowners’ Willingness to Supply Open Space Through Conservation Easements

Open space provides a range of benefits to many people of a community, beyond the benefits that accrue to private landowners. Parks and natural areas can be used for recreation; wetlands and forests supply storm-water drainage and wildlife habitat; farms and forests provide aesthetic benefits to surrounding residents. Moreover, undeveloped land can give relief from congestion. Agricultural lands are an important source of open space, but many of these lands are under great development pressure. One tool that is currently being used to aid in the preservation of open space by landowners is conservation easements. The rate of land protection by state and local land trusts has tripled since the beginning of the decade, and the West is the fastest growing region for both the number of acres under conservation easements and number of land trusts according to the Land Trust Alliance. Given the increased demand for amenities provided by private agricultural lands and the increased use of conservation easements, it is interesting to note that there is a paucity of research related to landowners’ preferences regarding conservation easements. The specific research objective of this paper is to determine important factors affecting an agricultural landowners’ potential choice regarding the placement of a parcel of land under a conservation easement. Knowing these factors could be useful to communities, public organizations and land trusts trying to provide open space to meet a growing demand for this public good. Information to construct a survey was obtained through a series of focus groups held in Wyoming and Colorado. Results from these focus groups were then used to develop twelve versions of a stated choice survey instrument. The first part of the survey included questions about the landowner’s specific community. These Likert scale questions were to designed to elicit a measurement of the respondents’ “sense of place” regarding his or her community. The second part of the survey questioned participants about their land and their land’s attributes, including what the landowner felt his land was worth, types of production and non-production activities land was used for, the types of developmental pressures being felt by the landowner, and the kinds of amenities he would like to conserve on his property. The third section of the survey included questions about the landowner’s personal knowledge of easements and two stated choice questions regarding conservation easements. These stated choice questions focused on five attributes: contract length, managerial control, wildlife habitat, access and payment. The final section of the survey asked respondents about demographic characteristics. Data were analyzed as a multinomial logit random utility model in LIMDEP. Respondents preferred an easement that was in perpetuity over an easement that was term in length. Respondents were less likely to accept an easement if public access on their property was required. As payment proportion in relation to the respondents’ perception of the value of their land went up, so did the likelihood that they would accept the easement. Landowners in Colorado were more likely to accept an easement than landowners in Wyoming. This is somewhat expected as developmental pressures in Colorado are higher than Wyoming, and thus far more easements have been transacted in Colorado than in Wyoming. Years on the land and connection to community were significant in explaining the acceptance of an easement scenario. The more connected one was to their community, the more likely they were to accept an easement. The longer a respondent had lived on their land, the more likely they were to accept an easement as well. The level of education a respondent had achieved negatively impacted easement acceptance. If an easement was already in place on a respondents’ property, the likelihood of accepting an easement scenario increased significantly.Land Economics/Use,

Historical Reconstruction of Population Density of the Echinoid Diadema antillarum on Florida Keys Shallow Bank-Barrier Reefs

The 1983–1984 caribbean-wide mass mortality of the once ubiquitous long-spined sea urchin Diadema antillarum Philippi, 1845, is one of several factors considered responsible for coral reef change throughout the region. Unfortunately, there is a paucity of pre-mortality event density data for D. antillarum in the Florida Keys, making it difficult to determine pre-1983 population density levels. results from surveys conducted during 1970–1973 in the lower Florida Keys, in shallow (\u3c12 m) fore reef habitats, yielded relatively abundant and widespread D. antillarum densities in qualitative transects at five reefs prior to the 1983–1984 die-off. In quantitative surveys at one reef, Middle sambo reef in 1972, up to 7.9 individuals m–2 were recorded using quadrats in high-relief spur and groove habitat. A second mortality event in the Florida Keys, beginning in April 1991, again depressed urchin densities that had begun to recover from the 1983–1984 mass mortality. By 1992, D. antillarum densities (\u3c0.01 m–2) were two orders of magnitude lower than pre-die-off estimates (range of 0.07–0.57 m–2 from several spur and groove reefs in the lower Florida Keys) and remained so through 2009. The pre-mortality echinoid density estimates detailed in the Florida Keys provide a baseline to compare with their current population status and should help inform managers about realistic recovery or restoration targets for D. antillarum

Ursinus College Alumni Journal, Spring 1942

Current comment • President\u27s page • Accelerated program data • Commencement advanced to May 15-18 weekend • Woman\u27s Club corner • Accelerated program puts May pageant in April • Noted speakers address campus organizations • College defense council formed • Students raise $200 for foreign student relief • Distinguished British scholar serves as visiting professor • Freshman customs changed • Alumni Association nominees • With the Grizzlies: Intramural program; Football to continue; Girls basketball; Varsity basketball; Freshman basketball; Wrestling • Publications choose editors • Miss Moll joins Army Nurses Corps • About ourselveshttps://digitalcommons.ursinus.edu/alumnijournal/1014/thumbnail.jp