Institution
University of New Hampshire
Education•Durham, New Hampshire, United States•
About: University of New Hampshire is a education organization based out in Durham, New Hampshire, United States. It is known for research contribution in the topics: Population & Solar wind. The organization has 9379 authors who have published 24025 publications receiving 1020112 citations. The organization is also known as: UNH.
Topics: Population, Solar wind, Poison control, Magnetosphere, Heliosphere
Papers published on a yearly basis
Papers
More filters
••
TL;DR: The findings show that there have been shifts in the timing of interacting species in recent decades; the next challenges are to improve the ability to predict the direction of change and understand the full consequences for communities and ecosystems.
Abstract: Phenological responses to climate change (e.g., earlier leaf-out or egg hatch date) are now well documented and clearly linked to rising temperatures in recent decades. Such shifts in the phenologies of interacting species may lead to shifts in their synchrony, with cascading community and ecosystem consequences. To date, single-system studies have provided no clear picture, either finding synchrony shifts may be extremely prevalent [Mayor SJ, et al. (2017) Sci Rep 7:1902] or relatively uncommon [Iler AM, et al. (2013) Glob Chang Biol 19:2348–2359], suggesting that shifts toward asynchrony may be infrequent. A meta-analytic approach would provide insights into global trends and how they are linked to climate change. We compared phenological shifts among pairwise species interactions (e.g., predator–prey) using published long-term time-series data of phenological events from aquatic and terrestrial ecosystems across four continents since 1951 to determine whether recent climate change has led to overall shifts in synchrony. We show that the relative timing of key life cycle events of interacting species has changed significantly over the past 35 years. Further, by comparing the period before major climate change (pre-1980s) and after, we show that estimated changes in phenology and synchrony are greater in recent decades. However, there has been no consistent trend in the direction of these changes. Our findings show that there have been shifts in the timing of interacting species in recent decades; the next challenges are to improve our ability to predict the direction of change and understand the full consequences for communities and ecosystems.
253 citations
••
TL;DR: These projections indicate that the ecosystem recovery processes that are primarily responsible for the contemporary U.S. carbon sink will slow over the next century, resulting in a significant reduction of the sink.
Abstract: Atmospheric and ground-based methods agree on the presence of a carbon sink in the coterminous United States (the United States minus Alaska and Hawaii), and the primary causes for the sink recently have been identified. Projecting the future behavior of the sink is necessary for projecting future net emissions. Here we use two models, the Ecosystem Demography model and a second simpler empirically based model (Miami Land Use History), to estimate the spatio-temporal patterns of ecosystem carbon stocks and fluxes resulting from land-use changes and fire suppression from 1700 to 2100. Our results are compared with other historical reconstructions of ecosystem carbon fluxes and to a detailed carbon budget for the 1980s. Our projections indicate that the ecosystem recovery processes that are primarily responsible for the contemporary U.S. carbon sink will slow over the next century, resulting in a significant reduction of the sink. The projected rate of decrease depends strongly on scenarios of future land use and the long-term effectiveness of fire suppression.
253 citations
••
TL;DR: It is shown that if the heart can be considered to be bounded by a closed surface, then the value of φm on this surface is uniquely related to the surface electrocardiogram to within a constant, provided there are no internal discontinuities.
Abstract: Cardiac muscle is considered to consist of an intracellular domain and an exracellular or interstitial domain. Current passes from one domain to the other through the cell membrane. Electric potentials in interstitial space are shown to be associated with current sources proportional to the spatial gradient of the cellular transmembrane action potential, φ
m
. Hence, given the distribution of φ
m
throughout the myocardium, one can calculate the surface electrocardiogram and extracorporeal magnetocardiogram. The problem is considerably complicated when anisotropy is considered. If interstitial space is approximately isotropic, however, the sources are still proportional to ∇φ
m
. It is shown that the effects of intracellular anisotropy on the surface electrocardiogram may be relatively small. The inverse problem is discussed briefly, with consideration of the relationship of the magnetocardiogram to the electrocardiogram. Finally, it is shown that if the heart can be considered to be bounded by a closed surface, then the value of φ
m
on this surface is uniquely related to the surface electrocardiogram to within a constant, provided there are no internal discontinuities. Such discontinuities, however, would be expected to occur in cases of ischemia and necrosis.
253 citations
••
TL;DR: In this paper, the relative importance of ozone, atmospheric nitrogen, CO2, and land use on forest growth and carbon balances was examined in a forest ecosystem model that was applied over the period of 1700-2000 under different scenarios of air pollution, land use, and human land use history.
Abstract: Temperate forests are affected by a wide variety of environmental factors that stem from human industrial and agricultural activities. In the north-eastern US, important change agents include tropospheric ozone, atmospheric nitrogen deposition, elevated CO2, and historical human land use. Although each of these has received attention for its effects on forest carbon dynamics, integrated analyses that examine their combined effects are rare. To examine the relative importance of all of these factors on current forest growth and carbon balances, we included them individually and in combination in a forest ecosystem model that was applied over the period of 1700–2000 under different scenarios of air pollution and land use history.
Results suggest that historical increases in CO2 and N deposition have stimulated forest growth and carbon uptake, but to different degrees following agriculture and timber harvesting. These differences resulted from the effects of each land use scenario on soil C and N pools and on the resulting degree of growth limitations by carbon vs. nitrogen. Including tropospheric ozone in the simulations offset a substantial portion of the increases caused by CO2 and N deposition. This result is particularly relevant given that ozone pollution is widespread across much of the world and because broad-scale spatial patterns of ozone are coupled with patterns of nitrogen oxide emissions. This was demonstrated across the study region by a significant correlation between ozone exposure and rates of N deposition and suggests that the reduction of N-induced carbon sinks by ozone may be a common phenomenon in other regions.
Collectively, the combined effects of all physical and chemical factors we addressed produced growth estimates that were surprisingly similar to estimates obtained in the absence of any form of disturbance. The implication of this result is that intact forests may show relatively little evidence of altered growth since preindustrial times despite substantial changes in their physical and chemical environment.
253 citations
•
14 Jul 1991TL;DR: A concept of interchangeability of CSP values is developed that permits recognition of some interchangeable values with polynomial time local computation and several forms of weak interchangeability are defined that permit eliminating values without losing all solutions.
Abstract: Constraint satisfaction problems (CSPs) involve finding values for variables subject to constraints on which combinations of values are permitted This paper develops a concept of interchangeability of CSP values Fully Interchangeable values can be substituted for one another in solutions to the problem Removing all but one of a set of fully interchangeable values can simplify the search space for the problem without effectively losing solutions Refinements of the interchangeability concept extend its applicability Basic properties of interchangeablity and complexity parameters are established A hierarchy of local interchangeability is defined that permits recognition of some interchangeable values with polynomial time local computation Computing local interchangeability at any level in this hierarchy to remove values before backtrack search is guaranteed to be cost effective for some CSPs Several forms of weak interchangeability are defined that permit eliminating values without losing all solutions Interchangeability can be introduced by grouping values or variables, and can be recalculated dynamically during search The idea of interchangeability can be abstracted to encompass any means of recovering the solutions involving one value from the solutions involving another
252 citations
Authors
Showing all 9489 results
Name | H-index | Papers | Citations |
---|---|---|---|
Derek R. Lovley | 168 | 582 | 95315 |
Peter B. Reich | 159 | 790 | 110377 |
Jerry M. Melillo | 134 | 383 | 68894 |
Katja Klein | 129 | 1499 | 87817 |
David Finkelhor | 117 | 382 | 58094 |
Howard A. Stone | 114 | 1033 | 64855 |
James O. Hill | 113 | 532 | 69636 |
Tadayuki Takahashi | 112 | 932 | 57501 |
Howard Eichenbaum | 108 | 279 | 44172 |
John D. Aber | 107 | 204 | 48500 |
Andrew W. Strong | 99 | 563 | 42475 |
Charles T. Driscoll | 97 | 554 | 37355 |
Andrew D. Richardson | 94 | 282 | 32850 |
Colin A. Chapman | 92 | 491 | 28217 |
Nicholas W. Lukacs | 91 | 367 | 34057 |