Getting the Swing of Surface Gravity

Sports are a popular and effective way to illustrate physics principles. Baseball in particular presents a number of opportunities to motivate student interest and teach concepts. Several articles have appeared in this journal on this topic, illustrating a wide variety of areas of physics. In addition, several websites and an entire book are available. In this paper we describe a student-designed project that illustrates the relative surface gravity on the Earth, Sun and other solar-system bodies using baseball. We describe the project and its results here as an example of a simple, fun, and student-driven use of baseball to illustrate an important physics principle

Global coverage of cetacean line-transect surveys : status quo, data gaps and future challenges

Knowledge of abundance, trends and distribution of cetacean populations is needed to inform marine conservation efforts, ecosystem models and spatial planning. We compiled a geo-spatial database of published data on cetacean abundance from dedicated visual line-transect surveys and encoded >1100 abundance estimates for 47 species from 430 surveys conducted worldwide from 1975-2005. Our subsequent analyses revealed large spatial, temporal and taxonomic variability and gaps in survey coverage. With the exception of Antarctic waters, survey coverage was biased toward the northern hemisphere, especially US and northern European waters. Overall, <25% of the world’s ocean surface was surveyed and only 6% had been covered frequently enough (≥ 5 times) to allow trend estimation. Almost half the global survey effort, defined as total area (km2) covered by all survey study areas across time, was concentrated in the Eastern Tropical Pacific (ETP). Neither the number of surveys conducted nor the survey effort had increased in recent years. Across species, an average of 10% of a species’ predicted range had been covered by at least one survey, but there was considerable variation among species. With the exception of three delphinid species, <1% of all species’ ranges had been covered frequently enough for trend analysis. We use a data-rich species, sperm whale, as an example to illustrate the challenges of using available data from line-transect surveys for the detection of trends or for spatial planning. Finally, we propose and contrast several field and analytical methods to fill in data gaps to improve future cetacean conservation management efforts.Publisher PDFPeer reviewe

Automorphism groups of countable algebraically closed graphs and endomorphisms of the random graph

We establish links between countable algebraically closed graphs and the endomorphisms of the countable universal graph $R$. As a consequence we show that, for any countable graph $\Gamma$, there are uncountably many maximal subgroups of the endomorphism monoid of $R$ isomorphic to the automorphism group of $\Gamma$. Further structural information about End $R$ is established including that Aut $\Gamma$ arises in uncountably many ways as a Sch\"{u}tzenberger group. Similar results are proved for the countable universal directed graph and the countable universal bipartite graph.Comment: Minor revision following referee's comments. 27 pages, 3 figure

Point-of-Use Water Treatment and Use among Mothers in Malawi

A national household survey was conducted in Malawi to determine awareness and use of a socially marketed water treatment product. In all, 64% of mothers were aware of the product, and 7% were using it. Both poor and rural mothers had lower awareness and use rates. Targeting promotion to rural populations could enhance program effectiveness

OASIS: a data and software distribution service for Open Science Grid

The Open Science Grid encourages the concept of software portability: a user's scientific application should be able to run at as many sites as possible. It is necessary to provide a mechanism for OSG Virtual Organizations to install software at sites. Since its initial release, the OSG Compute Element has provided an application software installation directory to Virtual Organizations, where they can create their own sub-directory, install software into that sub-directory, and have the directory shared on the worker nodes at that site. The current model has shortcomings with regard to permissions, policies, versioning, and the lack of a unified, collective procedure or toolset for deploying software across all sites. Therefore, a new mechanism for data and software distribution is desirable. The architecture for the OSG Application Software Installation Service (OASIS) is a server-client model: the software and data are installed only once in a single place, and are automatically distributed to all client sites simultaneously. Central file distribution offers other advantages, including server-side authentication and authorization, activity records, quota management, data validation and inspection, and well-defined versioning and deletion policies. The architecture, as well as a complete analysis of the current implementation, are described in this paper.This material is based on work supported by the National Science Foundation under NSF grants 647F231 and 1148698