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Search Results: 1 - 10 of 208524 matches for " L. Goodenough "
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Do Orientation-Based Differences in Nestbox Temperature Cause Differential Ectoparasite Load and Explain Patterns of Nest-Site Selection and Offspring Condition in Great Tits?
Anne E. Goodenough,Simon L. Elliot,Adam G. Hart
International Journal of Zoology , 2011, DOI: 10.1155/2011/514913
Abstract: Nest ectoparasites have been linked previously to patterns of nest-site choice and breeding success in birds. Recent research has shown nestboxes facing south-southwest are occupied less frequently by great tits (Parus major) than identical boxes facing other directions, and are associated with reduced offspring condition. Here, we investigate the hypothesis that these findings are due to ectoparasite load being directionally nonuniform, possibly because of nonuniformity in nestbox internal temperature. Nests contained, in order of prevalence, hen fleas (Ceratophyllus gallinae), haematophagous blowflies (Protocalliphora spp.), biting lice (Ischnocera), and ticks/mites (Acari). Although southwest-facing nestboxes were significantly warmer than other boxes, there was no directional difference in total ectoparasite load or abundance of particular species. Similarly, there was no relationship between abundance of any ectoparasite species (either per-nest or per-chick) and avian offspring condition determined using wing length or relative mass. We discuss several possible, nonmutually exclusive, explanations for this, including compensatory responses, costs of parasitism being transferred to parents, and condition-dependent effects. 1. Introduction Birds’ nests are occupied by more than just birds: they are an important habitat for a diverse invertebrate fauna. The nest structure becomes a miniature ecosystem of specialised nest-dwelling arthropods, comprising both ectoparasitic and free-living species [1, 2]. However, although arthropods are a common component of a breeding bird’s environment, ectoparasite abundance often exerts a strong influence on nest-site choice [3]. For example, the abundance of the haematophagous tropical fowl mite (Ornithonyssus bursa) influences nest-site choice in semicolonial barn swallows (Hirundo rustica) [4] while great tits (Parus major) avoid nest sites heavily infested with hen fleas (Ceratophyllus gallinae) [5]. Experimental studies on pied flycatchers (Ficedula hypoleuca) have shown preferential selection of nest sites where old nests have been removed to eradicate overwintering ectoparasites [6]. Avoidance of nest sites with high ectoparasite loads appears to be a behavioural response to avoid, or at least reduce, the negative effect of parasitism on the survival and condition of offspring [7]. Blood loss to haematophagous ectoparasites can result in anaemia and weight loss (e.g., [8, 9]) while ectoparasitism can also cause disease, either through ectoparasites acting as vectors [10, 11], or via postparasitism microbial
The Trouble with Thought Experiments
Jeremy Goodenough
Theoretical & Applied Ethics , 2011,
Abstract: What are thought experiments? What uses can they be put to and what problems do they face? In this paper I argue that thoughtexperiments are hard to define and that they face significant problems when used as a tool to draw out our moral or conceptualintuitions. The role of the intuition in our philosophical and ethical lives is also problematic. I go on to argue that the morefar-fetched thought experiments – and especially those that assume some kind of impossibility – face particular problems, andthat here bioethics can learn from the effects of the prolific use of modally problematic thought experiments in other areas ofphilosophy, such as the personal identity debate. I argue that, as the personal identity debate can best be approached by testingour conceptual intuitions against real-life cases, so the same may be true of bioethics. But, whether we use thought experimentsor real cases, we ought not to expect too much when seeking to apply concepts outside their standard range of application.
The Accuracy of Behavioural Data Collected by Visitors in a Zoo Environment: Can Visitors Collect Meaningful Data?
Rachel L. Williams,Sue K. Porter,Adam G. Hart,Anne E. Goodenough
International Journal of Zoology , 2012, DOI: 10.1155/2012/724835
Abstract: Volunteer data collection can be valuable for research. However, accuracy of such data is often a cause for concern. If clear, simple methods are used, volunteers can monitor species presence and abundance in a similar manner to professionals, but it is unknown whether volunteers could collect accurate data on animal behaviour. In this study, visitors at a Wetlands Centre were asked to record behavioural data for a group of captive otters by means of a short questionnaire. They were also asked to provide information about themselves to determine whether various factors would influence their ability to collect data. Using a novel analysis technique based on PCA, visitor data were compared to baseline activity budget data collected by a trained biologist to determine whether visitor data were accurate. Although the response rate was high, visitors were unable to collect accurate data. The principal reason was that visitors exceeded the observation time stated in the instructions, rather than being unable to record behaviours accurately. We propose that automated recording stations, such as touchscreen displays, might prevent this as well as other potential problems such as temporal autocorrelation of data and may result in accurate data collection by visiting members of the public. 1. Introduction Animal behaviour data are important across the field of biological sciences, from evolution and population biology to ethology in captive or domesticated animals. However, collecting these data is time consuming. Given that the duration of data collection for behavioural studies can range from several weeks [1, 2] to several years [3], funding professional researchers can be prohibitively expensive for many studies, especially those conducted by zoological parks and wildlife organisations [4, 5]. However, animal behaviour is of considerable interest to the general public (or at least a subset of the public with environmental and zoological interests), and many people spend considerable time observing animals as a hobby (e.g., watching pets, wild birds, or animals in zoos). Professionals could use this interest to recruit volunteers to record animal behaviour. There are many advantages of using volunteers to collect data. Volunteers can collect data at little or no financial cost to the organisation running the project [4–6]; indeed large numbers of untrained members of the public have been collecting biodiversity data for wildlife organisations for several decades. For example, in 2011, over 600,000 members of the public took part in the Royal Society for the
Using Long-Term Volunteer Records to Examine Dormouse (Muscardinus avellanarius) Nestbox Selection
Rachel L. Williams, Anne E. Goodenough, Adam G. Hart, Richard Stafford
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0067986
Abstract: Within ecology, there are unanswered questions about species-habitat interactions, which could potentially be resolved by a pragmatic analysis of a long-term volunteer-collected dataset. Here, we analysed 18 years of volunteer-collected data from a UK dormouse nestbox monitoring programme to determine the influence of habitat variables on nestbox choice by common dormice (Muscardinus avellanarius). We measured a range of habitat variables in a coppiced woodland in Gloucestershire, UK, and analysed these in relation to dormouse nestbox occupancy records (by dormice, other small mammals, and birds) collected by volunteers. While some characteristics of the woodland had changed over 18 years, simple transformation of the data and interpretation of the results indicated that the dataset was informative. Using stepwise regressions, multiple environmental and ecological factors were found to determine nestbox selection. Distance from the edge of the wood was the most influential (this did not change over 18 years), with boxes in the woodland interior being selected preferentially. There was a significant negative relationship with the presence of ferns (indicative of damp shady conditions). The presence of oak (a long-lived species), and the clumped structural complexity of the canopy were also important factors in the final model. There was no evidence of competition between dormice and birds or other mammals. The results provide greater understanding of artificial dormouse nest-site requirements and indicate that, in terms of habitat selection, long-term volunteer-collected datasets contribute usefully to understanding the requirements of species with an important conservation status.
Statistics on Graphs, Exponential Formula and Combinatorial Physics
L. Poinsot,G. H. E. Duchamp,S. Goodenough,K. A. Penson
Computer Science , 2009,
Abstract: The concern of this paper is a famous combinatorial formula known under the name "exponential formula". It occurs quite naturally in many contexts (physics, mathematics, computer science). Roughly speaking, it expresses that the exponential generating function of a whole structure is equal to the exponential of those of connected substructures. Keeping this descriptive statement as a guideline, we develop a general framework to handle many different situations in which the exponential formula can be applied.
Development of a Rapid and Precise Method of Digital Image Analysis to Quantify Canopy Density and Structural Complexity
Anne E. Goodenough,Andrew S. Goodenough
ISRN Ecology , 2012, DOI: 10.5402/2012/619842
Abstract: Estimation of canopy density is necessary for ecological research and woodland management. However, traditional manual methods are time consuming and subject to interobserver variability, while existing photographic methods usually require expensive fish-eye lenses and complex analysis. Here we introduce and test a new method of digital image analysis, CanopyDigi. This allows user-defined threshold to polarise the 256 grey shades of a standard monochrome bitmap into dark “canopy” and light “sky” pixels (the threshold being selected using false-colour images to ensure its suitability). Canopy density data are calculated automatically and rapidly, and, unlike many other common methods, aggregation data are obtainable using Morisita’s index to differentiate closed (diffuse light) and open (direct light) canopies. Results were highly repeatable in both homogeneous and heterogeneous woodland. Estimates correlated strongly with existing (nondigital) canopy techniques, but quicker and with significantly lower interobserver variability (CV = 3.74% versus 20.73%). We conclude that our new method is an inexpensive and precise technique for quantifying canopy density and aggregation. 1. Introduction Vegetation structural complexity comprises several parameters including the density and height of different vegetation layers, the percentage coverage of each layer, and species composition [1].In a woodland ecosystem, one of the most important aspects of overall structural complexity is the canopy density and aggregation [2, 3]. These parameters influence stand productivity and species composition, as well as the density and growth of the understorey, which is a key determinant of habitat [4]. Estimation of canopy coverage is important in studies of species-habitat relationships (e.g., [5–10]) and also for land managers given the increasing emphasis on sustainable woodland management. The effective use of canopy data in ecological research, or to inform woodland management, demands that measurements are accurate, precise, and obtainable using a quick, easy, and inexpensive method [11]. Estimates also need to have a high consistency and low interobserver variability to avoid generation of erroneous results [12–14]. 1.1. Canopy Measurements: Coverage and Density Somewhat surprisingly given its importance, there is no standard method of measuring canopy on a relatively small scale (e.g., for specific woodland plots). Jennings et al. [15] distinguish two basic types of measurement of forest canopies; the percentage of canopy coverage—the area of ground covered by a
A New Approach to Searching for Dark Matter Signals in Fermi-LAT Gamma Rays
Spencer Chang,Lisa Goodenough
Physics , 2009, DOI: 10.1088/1475-7516/2010/08/035
Abstract: Several cosmic ray experiments have measured excesses in electrons and positrons, relative to standard backgrounds, for energies from ~ 10 GeV - 1 TeV. These excesses could be due to new astrophysical sources, but an explanation in which the electrons and positrons are dark matter annihilation or decay products is also consistent. Fortunately, the Fermi-LAT diffuse gamma ray measurements can further test these models, since the electrons and positrons produce gamma rays in their interactions in the interstellar medium. Although the dark matter gamma ray signal consistent with the local electron and positron measurements should be quite large, as we review, there are substantial uncertainties in the modeling of diffuse backgrounds and, additionally, experimental uncertainties that make it difficult to claim a dark matter discovery. In this paper, we introduce an alternative method for understanding the diffuse gamma ray spectrum in which we take the intensity ratio in each energy bin of two different regions of the sky, thereby canceling common systematic uncertainties. For many spectra, this ratio fits well to a power law with a single break in energy. The two measured exponent indices are a robust discriminant between candidate models, and we demonstrate that dark matter annihilation scenarios can predict index values that require "extreme" parameters for background-only explanations.
Consequences of a Dark Disk for the Fermi and PAMELA Signals in Theories with a Sommerfeld Enhancement
Ilias Cholis,Lisa Goodenough
Physics , 2010, DOI: 10.1088/1475-7516/2010/09/010
Abstract: Much attention has been given to dark matter explanations of the PAMELA positron fraction and Fermi electronic excesses. For those theories with a TeV-scale WIMP annihilating through a light force-carrier, the associated Sommerfeld enhancement provides a natural explanation of the large boost factor needed to explain the signals, and the light force-carrier naturally gives rise to hard cosmic ray spectra without excess pi0 gamma rays or anti-protons. The Sommerfeld enhancement of the annihilation rate, which at low relative velocities v scales as 1/v, relies on the comparatively low velocity dispersion of the dark matter particles in the smooth halo. Dark matter substructures in which the velocity dispersion is smaller than in the smooth halo have even larger annihilation rates. N-body simulations containing only dark matter predict the existence of such structures, for example subhalos and caustics, and the effects of these substructures on dark matter indirect detection signals have been studied extensively. The addition of baryons into cosmological simulations of disk-dominated galaxies gives rise to an additional substructure component, a dark disk. The disk has a lower velocity dispersion than the spherical halo component by a factor ~6, so the contributions to dark matter signals from the disk can be more significant in Sommerfeld models than for WIMPs without such low-velocity enhancements. We consider the consequences of a dark disk on the observed signals of cosmic rays as measured by Fermi and PAMELA in models where the WIMP annihilations are into a light boson. We find that both the PAMELA and Fermi results are easily accomodated by scenarios in which a disk signal is included with the standard spherical halo signal. Limits from extrapolations to the center of the galaxy can also be modified.
Charge Asymmetric Cosmic Ray Signals From Dark Matter Decay
Spencer Chang,Lisa Goodenough
Physics , 2011, DOI: 10.1103/PhysRevD.84.023524
Abstract: The PAMELA and Fermi measurements of the cosmic-ray electron and positron spectra have generated much interest over the past two years, because they are consistent with a significant component of the electron and positron fluxes between 20 GeV and 1 TeV being produced through dark matter annihilation or decay. However, since the measurements are also consistent with astrophysical interpretations, the message is unclear. In this paper, we point out that dark matter can have a more distinct signal in cosmic rays, that of a charge asymmetry. Such charge asymmetry can result if the dark matter's abundance is due to a relic asymmetry, allowing its decay to generate an asymmetry in positrons and electrons. This is analogous to the baryon asymmetry, where decaying neutrons produce electrons and not positrons. We explore benchmark scenarios where the dark matter decays into a leptophilic charged Higgs boson or electroweak gauge bosons. These models have observable signals in gamma rays and neutrinos, which can be tested by Fermi and IceCube. The most powerful test will be at AMS-02, given its ability to distinguish electron and positron charge above 100 GeV. Specifically, an asymmetry favoring positrons typically predicts a larger positron ratio and a harder (softer) high energy spectrum for positrons (electrons) than charge symmetric sources. We end with a brief discussion on how such scenarios differ from the leading astrophysical explanations.
Dark Matter Annihilation in The Galactic Center As Seen by the Fermi Gamma Ray Space Telescope
Dan Hooper,Lisa Goodenough
Physics , 2010, DOI: 10.1016/j.physletb.2011.02.029
Abstract: We analyze the first two years of data from the Fermi Gamma Ray Space Telescope from the direction of the inner 10 degrees around the Galactic Center with the intention of constraining, or finding evidence of, annihilating dark matter. We find that the morphology and spectrum of the emission between 1.25 degrees and 10 degrees from the Galactic Center is well described by a the processes of decaying pions produced in cosmic ray collisions with gas, and the inverse Compton scattering of cosmic ray electrons in both the disk and bulge of the Inner Galaxy, along with gamma rays from known points sources in the region. The observed spectrum and morphology of the emission within approximately 1.25 degrees (~175 parsecs) of the Galactic Center, in contrast, departs from the expectations for by these processes. Instead, we find an additional component of gamma ray emission that is highly concentrated around the Galactic Center. The observed morphology of this component is consistent with that predicted from annihilating dark matter with a cusped (and possibly adiabatically contracted) halo distribution (density proportional to r^{-gamma}, with gamma=1.18 to 1.33). The observed spectrum of this component, which peaks at energies between 1-4 GeV (in E^2 units), can be well fit by a 7-10 GeV dark matter particle annihilating primarily to tau leptons with a cross section in the range of 4.6 x 10^-27 to 5.3 x 10^-26 cm^3/s, depending on how the dark matter distribution is normalized. We also discuss other sources for this emission, including the possibility that much of it originates from the Milky Way's supermassive black hole.
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