Inhomogeneous Condensates in Planar QED

We study the formation of vacuum condensates in $2+1$ dimensional QED in the presence of inhomogeneous background magnetic fields. For a large class of magnetic fields, the condensate is shown to be proportional to the inhomogeneous magnetic field, in the large flux limit. This may be viewed as a {\it local} form of the {\it integrated} degeneracy-flux relation of Aharonov and Casher.Comment: 13 pp, LaTeX, no figures; to appear in Phys. Rev.

Thermal Fluctuations of Induced Fermion Number

We analyze the phemomenon of induced fermion number at finite temperature. At finite temperature, the induced fermion number $$ is a thermal expectation value, and we compute the finite temperature fluctuations, $(\Delta N)^2=-^2$. While the zero temperature induced fermion number is topological and is a sharp observable, the finite temperature induced fermion number is generically nontopological, and is not a sharp observable. The fluctuations are due to the mixing of states inherent in any finite temperature expectation value. We analyze in detail two different cases in 1+1 dimensional field theory: fermions in a kink background, and fermions in a chiral sigma model background. At zero temperature the induced fermion numbers for these two cases are very similar, but at finite temperature they are very different. The sigma model case is generic and the induced fermion number is nontopological, but the kink case is special and the fermion number is topological, even at finite temperature. There is a simple physical interpretation of all these results in terms of the spectrum of the fermions in the relevant background, and many of the results generalize to higher dimensional models.Comment: 17 pgs, 9 figs, RevTex

Environmental Indicators for the Coastal Region of the U.S. Great Lakes

The goal of this research collaboration was to develop indicators that both estimate environmental condition and suggest plausible causes of ecosystem degradation in the coastal region of the U.S. Great Lakes. The collaboration consisted of 8 broad components, each of which generated different types of environmental responses and characteristics of the coastal region. These indicators included biotic communities of amphibians, birds, diatoms, fish, macroinvertebrates, and wetland plants as well as indicators of polycyclic aromatic hydrocarbon (PAH) photo-induced toxicity and landscape characterization. These components are summarized below and discussed in more detailed in 5 separate reports (Section II). Stress gradients within the U.S. Great Lakes coastal region were defined from 207 variables (e.g., agriculture, atmospheric deposition, land use/land cover, human populations, point source pollution, and shoreline modification) from 19 different data sources that were publicly available for the coastal region. Biotic communities along these gradients were sampled with a stratified, random design among representative ecosystems within the coastal zone. To achieve the sampling across this massive area, the coastal region was subdivided into 2 major ecological provinces and further subdivided into 762 segment sheds. Stress gradients were defined for the major categories of human-induced disturbance in the coastal region and an overall stress index was calculated which represented a combination of all the stress gradients. Investigators of this collaboration have had extensive interactions with the Great Lakes community. For instance, the Lake Erie Lakewide Area Management Plan (LAMP) has adopted many of the stressor measures as integral indicators of the condition of watersheds tributary to Lake Erie. Furthermore, the conceptual approach and applications for development of a generalized stressor gradient have been incorporated into a document defining the tiered aquatic life criteria for defining biological integrity of the nation’s waters. A total of 14 indicators of the U.S. Great Lakes coastal region are presented for potential application. Each indicator is summarized with respect to its use, methodology, spatial context, and diagnosis capability. In general, the results indicate that stress related to agricultural activity and human population density/development had the largest impacts on the biotic community indicators. In contrast, the photoinduced PAH indicator was primarily related to industrial activity in the U.S. Great Lakes, and over half of the sites sampled were potentially at risk of PAH toxicity to larval fish. One of the indicators developed for land use/land change was developed from Landsat imagery for the entire U.S. Great Lakes basin and for the period from 1992 to 2001. This indicator quantified the extensive conversions of both agricultural and forest land to residential area that has occurred during a short 9 year period. Considerable variation in the responses were manifest at different spatial scales and many at surprisingly large scales. Significant advances were made with respect to development of methods for identifying and testing environmental indicators. In addition, many indicators and concepts developed from this project are being incorporated into management plans and U.S. 8 EPA methods documents. Further details, downloadable documents, and updates on these indicators can be found at the GLEI website - http://glei.nrri.umn.edu

Defining Space Use and Movements of Canada Lynx with Global Positioning System Telemetry

Space use and movements of Canada lynx (Lynx canadensis) are difficult to study with very-high-frequency radiocollars. We deployed global positioning system (GPS) collars on 11 lynx in Minnesota to study their seasonal space-use patterns. We estimated home ranges with minimum-convex-polygon and fixed-kernel methods and estimated core areas with area/probability curves. Fixed-kernel home ranges of males (range = 29–522 km2) were significantly larger than those of females (range = 5–95 km2) annually and during the denning season. Some male lynx increased movements during March, the month most influenced by breeding activity. Lynx core areas were predicted by the 60% fixed-kernel isopleth in most seasons. The mean core-area size of males (range = 6–190 km2) was significantly larger than that of females (range = 1–19 km2) annually and during denning. Most female lynx were reproductive animals with reduced movements, whereas males often ranged widely between Minnesota and Ontario. Sensitivity analyses examining the effect of location frequency on homerange size suggest that the home-range sizes of breeding females are less sensitive to sample size than those of males. Longer periods between locations decreased home-range and core-area overlap relative to the home range estimated from daily locations. GPS collars improve our understanding of space use and movements by lynx by increasing the spatial extent and temporal frequency of monitoring and allowing home ranges to be estimated over short periods that are relevant to life-history characteristics

Natural Resources Research Institute Technical Report

In this report we summarize accomplishments of the Canada Lynx Ecology in the Great Lakes Region project. We carried out initial work in the Superior National Forest to address 4 major questions about this Canada lynx population: distribution, abundance, persistence, and habitat requirements. In the first 8 months of this project we have captured and deployed radiotelemetry collars on 8 Canada lynx. Each animal was relocated approximately weekly after being collared. Of the 8 Canada lynx that have been collared, 2 have died. Two of the collars deployed on Canada lynx were GPS collars. This marked the first time ever that a GPS collar was deployed on Canada lynx. We downloaded the locations from one of these GPS collars when one of the collared animals was recaptured on December 30th, 2003 after wearing the GPS collar for 3 weeks. The importance of GPS collar data for understanding movements and habitat use of Canada lynx should not be underestimated. In addition to the telemetry research, we have also conducted the first year of surveys for the major prey species of Canada lynx: snowshoe hare and red squirrel. Permanent pellet plots were established throughout the SNF for snowshoe hare. Plots were distributed based on stratified random, systematic, and selective site selection strategies. We established new plots to estimate red squirrel abundance in an area of known high lynx density, and also utilized an existing long-term data set for red squirrel abundance from SNF. Another year of surveys following the National Lynx Survey protocol was completed, and a snow-track survey for Canada lynx and other mesocarnivores was completed on the National Lynx Survey grid. There were also many opportunities to disseminate information on Canada lynx to the biological community and to the general public. More than 10 presentations on lynx biology were given by project personnel. Project personnel assisted in planning, helped with field trips, and gave presentations at the National Lynx and Wolverine Steering Committee Meeting in May 2003 and the Interagency Lynx Biology Team Meeting in October 2003, both of which were hosted by SNF. We have developed a website for the Canada Lynx Ecology in the Great Lakes Region project (www.nrri.umn.edu/lynx). This website provides a history of the project, lists project goals and accomplishments, and includes links to press coverage of the project. We begin the report with a brief chronological summary of the Canada lynx ecology in the Great Lakes Region project. The project was supported by several agencies with some common deliverables and some deliverables that varied among agencies. To produce a cohesive, logically organized Annual Report, we describe the project in its entirety, and we indicate specific deliverables in Appendix 1. We first describe Canada lynx trapping and the deployment of radiotelemetry collars. The radiotelemetry program is very important because each of the major deliverables depends on telemetry data. Next, we address progress made on each of the major questions: (1) Location, (2) Distribution, (3) Persistence, and (4) Habitat use. Prey species surveys and National Lynx Survey results are also summarized. We conclude each section with the current status and future plans for each research topic. We believe it is important to recognize that the project is only 8 months old. A complete answer for any of the questions will require the several years of data collection which is built into the project master plan. We caution that results presented in this report are preliminary because of the few animals that have been collared, and because of the relatively few locations that have been obtained. Management recommendations should not be made from the little information that has been obtained to date. However, with the number of Canada lynx now radiocollared, and with expectations of more in the near future, there will be sufficient data for management recommendations by the end of the second year of this project

Natural Resources Research Institute Technical Report

A variety of non-invasive techniques including hair snagging, snow-tracking, and remote cameras can be used to monitor mammalian carnivores. The National Interagency Canada Lynx Detection Survey (NLDS) was a survey designed to detect lynx with a hair-snagging protocol applied throughout the conterminous U.S. range of the lynx. Hare-snagging stations consisted of a scent lure, a carpet piece with nails to snag hair, and a pie tin to attract the cat’s attention. We applied the NLDS protocol in the Superior and Chippewa National Forests in Minnesota, the Chequamegon and Nicolet National Forests in Wisconsin, and the Ottawa National Forest in Michigan. Mammalian species detected included black bears (Ursus americanus), bobcats (Lynx rufus), coyotes (Canis latrans), ungulates, and other canids. The NLDS did not detect lynx in the Great Lakes Geographic Area (GLGA) despite their likely presence on some of the Minnesota NLDS grids. We also opportunistically set up hair snagging stations in areas in Minnesota where we knew lynx were present to further test the efficacy of hair-snagging stations. We had limited success using hair snares to selectively sample for lynx despite placing snares in areas regularly used by lynx. We suspect the detection probability for lynx hair-snagging surveys in the GLGA may be low and other survey techniques may prove more useful, particularly for localized selective sampling for lynx presence

Vegetation controls vary across space and spatial scale in a historic grassland-forest biome boundary. Ecography 34:402

Ecological boundaries are critical landscape regions of transition between adjacent ecological systems. While environmental controls of boundaries may operate in a scale-dependent manner, multiple-scale comparisons of vegetationÁenvironment relationships have been characterized for few boundary systems. We used approximately 250 000 point records on the occurrence of woody versus grassland vegetation in conjunction with climatic, topographical, and soils data to evaluate scale effects and spatial heterogeneity in a 650-km section of the historic prairieÁforest biome boundary of Minnesota, USA. We chose this as a model system because of the availability of historical vegetation data, a considerable spatial extent, a sharp ecological transition, and the ability to avoid confounding from more recent anthropogenic land use change. We developed modeling techniques using hierarchical variance partitioning in a spatially-structured format that allowed us to simultaneously evaluate vegetationÁenvironment relationships across two-dimensional space (i.e. the prairie-forest boundary) and across spatial scales (i.e. varying extents). Soils variables displayed the least spatial autocorrelation at shortest lag distances and tended to be the least important predictors of woody vegetation at all spatial extents. Topographical variables displayed greater spatial heterogeneity in regions dominated by forest compared with prairie and were more important at fine-intermediate spatial scales, highlighting their likely control on fire regimes. An integrated climatic variable (precipitation minus potential evapotranspiration) displayed a trend of increasing spatial variance across the study region and was unambiguously the strongest biome boundary control, although its joint influence with fire was difficult to characterize. Spatially heterogeneous vegetationÁenvironment relationships were observed at all scales, especially at finer scales. Our results suggest that the importance of environmental controls changes smoothly rather than discretely across scales and demonstrate the need to account for spatial non-stationarity and scale to predict and understand vegetation distribution across ecological boundaries

Report to Dr. A. Petersen, Vice President for Research, Dr. A. Hopkins, Vice President for Arts, Sciences, and Engineering, University of Minnesota on Water Water Sciences, Technology, Education and Research

Report presents a strategy to build a coherent community of water scientists