Institution
University of Notre Dame
Education•Notre Dame, Indiana, United States•
About: University of Notre Dame is a education organization based out in Notre Dame, Indiana, United States. It is known for research contribution in the topics: Population & Large Hadron Collider. The organization has 22238 authors who have published 55201 publications receiving 2032925 citations. The organization is also known as: University of Notre Dame du Lac & University of Notre Dame, South Bend.
Topics: Population, Large Hadron Collider, Standard Model, Politics, Lepton
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TL;DR: This work addresses the issue of management of freshwater exotic species on lakes or drainages that are both vulnerable to colonization by an exotic, and that harbour endemic species, with different spatial scales of experiments testing the impact of two predators on native snail assemblages.
Abstract: Global homogenization of biota is underway through worldwide introduction and establishment of nonindigenous (exotic) species. Freshwater ecologists should devote more attention to exotic species for two reasons. First, exotics provide an opportunity to test hypotheses about what characteristics of species or habitats are related to successful establishment or invasibility, respectively. Second, predicting which species will cause large ecological change is an important challenge for natural resource managers. Rigorous statistical relationships linking species characteristics to probability of establishment or of causing ecological impacts are needed. In addition, it is important to know how reliable different sorts of experiments are in guiding predictions. We address this issue with different spatial scales of experiments testing the impact of two predators on native snail assemblages in northern Wisconsin USA lakes: an exotic crayfish, the rusty crayfish (Orconectes rusticus); and a native fish predator, the pumpkinseed sunfish (Lepomis gibossus). For the crayfish, laboratory experiments, a field cage experiment, and a snapshot survey of 21 lakes gave consistent results: the crayfish reduced abundance and species richness of native snails. Laboratory and field experiments suggested that pumpkinseed sunfish should have a similar impact, but the lake survey suggested little impact. Unfortunately, no algorithms exist to guide scaling up from small-scale experiments to the whole-lake, long-term management scale. To protect native biodiversity, management of freshwater exotic species should be targeted on lakes or drainages that are both vulnerable to colonization by an exotic, and that harbour endemic species. Management should focus on preventing introduction because eradication after establishment is usually not possible.
311 citations
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University of California, Berkeley1, European Southern Observatory2, Harvard University3, Las Cumbres Observatory Global Telescope Network4, University of Colorado Boulder5, Spanish National Research Council6, University of Chicago7, Lawrence Livermore National Laboratory8, University of California, Davis9, University of Arizona10, University of Notre Dame11, University of California, Santa Cruz12, University of Texas at Austin13, University of Hawaii at Manoa14, University of Pittsburgh15
TL;DR: In this paper, the authors presented extensive early photometric and spectroscopic (optical and near-infrared) data on supernova (SN) 2008D as well as X-ray data analysis on the associated Swift Xray transient (XRT) 080109.
Abstract: We present extensive early photometric (ultraviolet through near-infrared) and spectroscopic (optical and near-infrared) data on supernova (SN) 2008D as well as X-ray data analysis on the associated Swift X-ray transient (XRT) 080109. Our data span a time range of 5 hr before the detection of the X-ray transient to 150days after its detection, and a detailed analysis allowed us to derive constraints on the nature of the SN and its progenitor; throughout we draw comparisons with results presented in the literature and find several key aspects that differ. We show that the X-ray spectrum of XRT 080109 can be fit equally well by an absorbed power law or a superposition of about equal parts of both power law and blackbody. Our data first established that SN 2008D is a spectroscopically normal SN Ib (i.e., showing conspicuous He lines) and showed that SN 2008D had a relatively long rise time of 18days and a modest optical peak luminosity. The early-time light curves of the SN are dominated by a cooling stellar envelope (for Δt0.1-4days, most pronounced in the blue bands) followed by 56Ni decay. We construct a reliable measurement of the bolometric output for this stripped-envelope SN, and, combined with estimates of E K and M ej from the literature, estimate the stellar radius R ⊙ of its probable Wolf-Rayet progenitor. According to the model of Waxman etal. and Chevalier & Fransson, we derive R W07⊙ = 1.2 0.7R ⊙ and R CF08⊙ = 12 7 R ⊙, respectively; the latter being more in line with typical WN stars. Spectra obtained at three and four months after maximum light show double-peaked oxygen lines that we associate with departures from spherical symmetry, as has been suggested for the inner ejecta of a number of SN Ib cores. © 2009. The American Astronomical Society. All rights reserved.
311 citations
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TL;DR: The authors assessed the importance of water table and soil temperature as controls over ecosystem respiration in a bog and sedge fen in northern Minnesota, USA, by means of a manipulative mesocosm experiment.
Abstract: Projected changes in climate could shift northern peatlands from their current status as net C sinks toward that of being net C sources by changing soil temperatures and hydrology. We assessed the importance of water table and soil temperature as controls over ecosystem respiration in a bog and sedge fen in northern Minnesota, USA, by means of a manipulative mesocosm experiment. Fifty-four intact monoliths were removed from a bog and a fen and installed in insulated tanks that permitted control of the water table and were heated by overhead infrared heaters. The experimental design was a fully crossed factorial combination of two communities, three water tables, and three heat levels. Ecosystem respiration as indicated by emission of CO2 and CH4, dissolved nutrient fluxes, and productivity were measured and summarized for each growing season from 1995 to 1997.
Seasonal ecosystem respiration (ER) as indicated by CO2 emissions responded almost exclusively to soil temperature and did not differ between community types (∼630 g C/m2) or with water table level. These results suggest that community type, within certain limits, will not be an important factor in predicting temperature-driven increases in ER.
The response of CH4 flux to soil temperature and water table setting became progressively stronger in each succeeding growing season. Seasonal CH4 emissions were on average three times higher in the bog than in the fen mesocosms (21 vs. 7 g C/m2). Aboveground net primary productivity and dissolved N retention were also higher in the bog mesocosms. There were strong correlations between CH4 flux and N retention, but generally weak correlations between CH4 and plant primary production. The relatively lower CH4 emissions from the fen mesocosms appear to result mainly from higher rates of methanotrophy in the aerated zone, possibly reinforced by the effects of higher porewater N concentrations and lower primary productivity compared to the bogs.
The results confirm the existence of strong environmental controls over ER and methanogenesis, which are modulated by complex interactions between plant community and soil nutrient dynamics. The differential responses of these ecosystem functions to climate change may complicate efforts to predict future changes in C dynamics in these important repositories of soil C.
311 citations
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13 Dec 1995TL;DR: In this paper, the authors introduce the notion of invariant set (e.g., equilibrium) for hybrid dynamical systems and define several types of (Lyapunov-like) stability concepts for invariant sets.
Abstract: Hybrid systems which are capable of exhibiting simultaneously several kinds of dynamic behavior in different parts of a system are of great current interest. In the present paper we first formulate a definition of hybrid dynamical system which covers a very large number of classes of hybrid systems and which is suitable for the qualitative analysis of such systems. Next, we introduce the notion of invariant set (e.g., equilibrium) for hybrid dynamical systems and we define several types of (Lyapunov-like) stability concepts for an invariant set. We then establish sufficient conditions for the uniform stability and the uniform asymptotic stability of an invariant set of a hybrid dynamical system. Under some mild additional assumptions, we also establish necessary conditions for some of the above stability types (converse theorems). To demonstrate the applicability of the developed theory, we present two specific examples of hybrid dynamical systems and we conduct a stability analysis of one of these examples (a sampled-data feedback control system with a nonlinear (continuous-time) plant and a linear (discrete-time) controller).
310 citations
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TL;DR: An approach to sample size planning for multiple regression is presented that emphasizes accuracy in parameter estimation (AIPE) by providing necessary sample sizes in order for the likely widths of confidence intervals to be sufficiently narrow.
Abstract: An approach to sample size planning for multiple regression is presented that emphasizes accuracy in parameter estimation (AIPE). The AIPE approach yields precise estimates of population parameters by providing necessary sample sizes in order for the likely widths of confidence intervals to be sufficiently narrow. One AIPE method yields a sample size such that the expected width of the confidence interval around the standardized population regression coefficient is equal to the width specified. An enhanced formulation ensures, with some stipulated probability, that the width of the confidence interval will be no larger than the width specified. Issues involving standardized regression coefficients and random predictors are discussed, as are the philosophical differences between AIPE and the power analytic approaches to sample size planning.
310 citations
Authors
Showing all 22586 results
Name | H-index | Papers | Citations |
---|---|---|---|
George Davey Smith | 224 | 2540 | 248373 |
David Miller | 203 | 2573 | 204840 |
Patrick O. Brown | 183 | 755 | 200985 |
Dorret I. Boomsma | 176 | 1507 | 136353 |
Chad A. Mirkin | 164 | 1078 | 134254 |
Darien Wood | 160 | 2174 | 136596 |
Wei Li | 158 | 1855 | 124748 |
Timothy C. Beers | 156 | 934 | 102581 |
Todd Adams | 154 | 1866 | 143110 |
Albert-László Barabási | 152 | 438 | 200119 |
T. J. Pearson | 150 | 895 | 126533 |
Amartya Sen | 149 | 689 | 141907 |
Christopher Hill | 144 | 1562 | 128098 |
Tim Adye | 143 | 1898 | 109010 |
Teruki Kamon | 142 | 2034 | 115633 |