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Search Results: 1 - 10 of 462553 matches for " A. Rosenberg "
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Changing U.S. Ocean Policy Can Set a New Direction for Marine Resource Management
Andrew A. Rosenberg
Ecology and Society , 2009,
Abstract: A central concept in a new direction for ocean policy in the United States is ecosystem-based management, that is, implementation of management integrated across sectors of human activity to achieve the common goal of conserving the structure and function of marine ecosystems to provide a full suite of ecosystem services. Fisheries are a critical sector of ocean activity that impacts these ecosystems, and fishery management is in urgent need of reform to perform better from a conservation perspective. Here, I suggest some specific changes in perspective for fishery management as part of an overall ecosystem-based approach.
Identifying and promoting safe walking routes in older adults  [PDF]
Jacqueline Kerr, Jordan A. Carlson, Dori E. Rosenberg, Ashley Withers
Health (Health) , 2012, DOI: 10.4236/health.2012.429112
Abstract: Background: Walking for physical activity is important for older adults' physical and mental health. We developed and tested the reliability of an environmental audit tool designed to be used by lay people to identify appropriate walking routes for older adults trying to increase their physical activity. Methods: A 44-item Walking Route Audit Tool for Seniors (WRATS) was developed based on literature review and input from older adults during focus groups. Observers completed the tool for 24 walking routes which were specifically selected to maximize variability in environment features and quality. Inter-rater reliability was assessed using Kappa and percent agreement. Results: Inter-rater reliability was good to excellent for 27 of the 44 WRATS items and moderate for 9 items. ICCs were good to excellent for 6 of the 8 scales (ICCs = 0.61 to 0.90). Conclusions: These results provide evidence for the reliability of WRATS for evaluating environmental attributes of walking routes suitable for older adults. Some scales need further refinement, and validity should be tested in a sample of older adults.
Minimal surfaces and harmonic diffeomorphisms from the complex plane onto a Hadamard surface
Jose A. Galvez,Harold Rosenberg
Mathematics , 2008,
Abstract: We construct harmonic diffeomorphisms from the complex plane $C$ onto any Hadamard surface $M$ whose curvature is bounded above by a negative constant. For that, we prove a Jenkins-Serrin type theorem for minimal graphs in $M\times R$ over domains of $M$ bounded by ideal geodesic polygons and show the existence of a sequence of minimal graphs over polygonal domains converging to an entire minimal graph in $M\times R$ with the conformal structure of $C$.
On the number of ranked species trees producing anomalous ranked gene trees
Filippo Disanto,Noah A. Rosenberg
Quantitative Biology , 2014,
Abstract: Analysis of probability distributions conditional on species trees has demonstrated the existence of anomalous ranked gene trees (ARGTs), ranked gene trees that are more probable than the ranked gene tree that accords with the ranked species tree. Here, to improve the characterization of ARGTs, we study enumerative and probabilistic properties of two classes of ranked labeled species trees, focusing on the presence or avoidance of certain subtree patterns associated with the production of ARGTs. We provide exact enumerations and asymptotic estimates for cardinalities of these sets of trees, showing that as the number of species increases without bound, the fraction of all ranked labeled species trees that are ARGT-producing approaches 1. This result extends beyond earlier existence results to provide a probabilistic claim about the frequency of ARGTs.
Coalescent histories for lodgepole species trees
Filippo Disanto,Noah A. Rosenberg
Quantitative Biology , 2015,
Abstract: Coalescent histories are combinatorial structures that describe for a given gene tree and species tree the possible lists of branches of the species tree on which the gene tree coalescences take place. Properties of the number of coalescent histories for gene trees and species trees affect a variety of probabilistic calculations in mathematical phylogenetics. Exact and asymptotic evaluations of the number of coalescent histories, however, are known only in a limited number of cases. Here we introduce a particular family of species trees, the \emph{lodgepole} species trees $(\lambda_n)_{n\geq 0}$, in which tree $\lambda_n$ has $m=2n+1$ taxa. We determine the number of coalescent histories for the lodgepole species trees, in the case that the gene tree matches the species tree, showing that this number grows with $m!!$ in the number of taxa $m$. This computation demonstrates the existence of tree families in which the growth in the number of coalescent histories is faster than exponential. Further, it provides a substantial improvement on the lower bound for the ratio of the largest number of matching coalescent histories to the smallest number of matching coalescent histories for trees with $m$ taxa, increasing a previous bound of $(\sqrt{\pi} / 32)[(5m-12)/(4m-6)] m \sqrt{m}$ to $[ \sqrt{m-1}/(4 \sqrt{e}) ]^{m}$. We discuss the implications of our enumerative results for phylogenetic computations.
Asymptotic properties of the number of matching coalescent histories for caterpillar-like families of species trees
Filippo Disanto,Noah A. Rosenberg
Quantitative Biology , 2015,
Abstract: Coalescent histories provide lists of species tree branches on which gene tree coalescences can take place, and their enumerative properties assist in understanding the computational complexity of calculations central in the study of gene trees and species trees. Here, we solve an enumerative problem left open by Rosenberg (IEEE/ACM Transactions on Computational Biology and Bioinformatics 10: 1253-1262, 2013) concerning the number of coalescent histories for gene trees and species trees with a matching labeled topology that belongs to a generic caterpillar-like family. By bringing a generating function approach to the study of coalescent histories, we prove that for any caterpillar-like family with seed tree $t$, the sequence $(h_n)_{n\geq 0}$ describing the number of matching coalescent histories of the $n$th tree of the family grows asymptotically as a constant multiple of the Catalan numbers. Thus, $h_n \sim \beta_t c_n$, where the asymptotic constant $\beta_t > 0$ depends on the shape of the seed tree $t$. The result extends a claim demonstrated only for seed trees with at most 8 taxa to arbitrary seed trees, expanding the set of cases for which detailed enumerative properties of coalescent histories can be determined. We introduce a procedure that computes from $t$ the constant $\beta_t$ as well as the algebraic expression for the generating function of the sequence $(h_n)_{n\geq 0}$.
Striking Century-Long Changes in Marine Benthos  [PDF]
Rutger Rosenberg
Journal of Environmental Protection (JEP) , 2014, DOI: 10.4236/jep.2014.513125
Abstract: One of the oldest published records of benthic fauna was made in 1893 by dredging along transects from soft bottoms, sand and shell debris to rocky bottoms in an archipelago at the Swedish Skagerrak coast. Three of the transects were revisited in 2010 and then fewer taxa were recorded and the shared species between sampling dates at the transects were only between 8% and 12%. The main causes for the drastic changes are suggested to be large-scale eutrophication changing the vegetation composition and variation of climatic factors.
Discordance of Species Trees with Their Most Likely Gene Trees
James H Degnan,Noah A Rosenberg
PLOS Genetics , 2006, DOI: 10.1371/journal.pgen.0020068
Abstract: Because of the stochastic way in which lineages sort during speciation, gene trees may differ in topology from each other and from species trees. Surprisingly, assuming that genetic lineages follow a coalescent model of within-species evolution, we find that for any species tree topology with five or more species, there exist branch lengths for which gene tree discordance is so common that the most likely gene tree topology to evolve along the branches of a species tree differs from the species phylogeny. This counterintuitive result implies that in combining data on multiple loci, the straightforward procedure of using the most frequently observed gene tree topology as an estimate of the species tree topology can be asymptotically guaranteed to produce an incorrect estimate. We conclude with suggestions that can aid in overcoming this new obstacle to accurate genomic inference of species phylogenies.
Species-Specific Traits Rather Than Resource Partitioning Mediate Diversity Effects on Resource Use
Jasmin A. Godbold,Rutger Rosenberg,Martin Solan
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0007423
Abstract: The link between biodiversity and ecosystem processes has firmly been established, but the mechanisms underpinning this relationship are poorly documented. Most studies have focused on terrestrial plant systems where resource use can be difficult to quantify as species rely on a limited number of common resources. Investigating resource use at the bulk level may not always be of sufficient resolution to detect subtle differences in resource use, as species-specific nutritional niches at the biochemical level may also moderate diversity effects on resource use.
A decision tree model to estimate the value of information provided by a groundwater quality monitoring network
A. Khader,D. Rosenberg,M. McKee
Hydrology and Earth System Sciences Discussions , 2012, DOI: 10.5194/hessd-9-13805-2012
Abstract: Nitrate pollution poses a health risk for infants whose freshwater drinking source is groundwater. This risk creates a need to design an effective groundwater monitoring network, acquire information on groundwater conditions, and use acquired information to inform management. These actions require time, money, and effort. This paper presents a method to estimate the value of information (VOI) provided by a groundwater quality monitoring network located in an aquifer whose water poses a spatially heterogeneous and uncertain health risk. A decision tree model describes the structure of the decision alternatives facing the decision maker and the expected outcomes from these alternatives. The alternatives include: (i) ignore the health risk of nitrate contaminated water, (ii) switch to alternative water sources such as bottled water, or (iii) implement a previously designed groundwater quality monitoring network that takes into account uncertainties in aquifer properties, pollution transport processes, and climate (Khader and McKee, 2012). The VOI is estimated as the difference between the expected costs of implementing the monitoring network and the lowest-cost uninformed alternative. We illustrate the method for the Eocene Aquifer, West Bank, Palestine where methemoglobinemia is the main health problem associated with the principal pollutant nitrate. The expected cost of each alternative is estimated as the weighted sum of the costs and probabilities (likelihoods) associated with the uncertain outcomes resulting from the alternative. Uncertain outcomes include actual nitrate concentrations in the aquifer, concentrations reported by the monitoring system, whether people abide by manager recommendations to use/not-use aquifer water, and whether people get sick from drinking contaminated water. Outcome costs include healthcare for methemoglobinemia, purchase of bottled water, and installation and maintenance of the groundwater monitoring system. At current methemoglobinemia and bottled water costs of 150 $/person and 0.6 $/baby/day, the decision tree results show that the expected cost of establishing the proposed groundwater quality monitoring network exceeds the expected costs of the uninformed alternatives and there is not value to the information the monitoring system provides. However, the monitoring system will be preferred to ignoring the health risk or using alternative sources if the methemoglobinemia cost rises to 300 $/person or the bottled water cost increases to 2.3 $/baby/day. Similarly, the monitoring system has value if the system can more ac
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