391 research outputs found

    Vertical variation in flight activity of the lesser short-tailed bat in podocarp and beech forests, Central North Island, New Zealand

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    Designing robust monitoring programmes for cryptic species is particularly difficult. Not detecting a species does not necessarily mean that it is absent from the sampling area. A conclusion of absence made in error can lead to misguided inferences about distribution, colonisation and local extinction estimates, which in turn affects where and how conservation actions are undertaken. It is therefore important to investigate monitoring techniques that reduce the non-detection rate of cryptic species. As habitat complexity plays an important role in the activity of bats within a forest, it was hypothesised that the amount of vegetative ‘clutter’ present at different heights within two different forest types affected the flight activity of lesser short-tailed bats (Mystacina tuberculata). This could affect detection of the species within different forest structures. To compare bat activity at three heights – top (22.0–25.0 m), middle (10.0–12.0 m) and bottom (1.5–2.0 m) – within a podocarp and a beech forest we used automatic bat monitors during January to March 2005. The number of bat passes was recorded at each height at two study areas within each forest and compared between forest types. The forest structure was described using the Recce method and vegetative cover estimated within the three height tiers sampled for bat activity. Within both forest types, the middle-level bat detectors logged the greatest amount of activity. However, differences between the forest types were most pronounced closer to the ground, where a high amount of activity was detected within the beech forest, and very little within the podocarp forest. This suggests that flight activity of lesser short-tailed bats may be affected by the level of vegetative clutter found at different heights within a forest. When designing monitoring programmes for lesser short-tailed bats, it is recommended that consideration be given to the forest structure and how this may affect detection of bat activity

    Identity and Immigration Integration in Western Europe’s ‘New’ Migration Cities: The Cases of Dublin and Madrid

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    As Ireland and Spain transformed into immigration countries in the early 2000s, they attracted comparatively large immigrant populations, especially to their largest cities. Nonetheless, the immigrant communities in Dublin and Madrid differ significantly in their composition, the reaction they have elicited from the host society, and their ability to incorporate in their new environment. This paper explores the factors that influence immigrant reception and integration in new immigration spaces like Dublin and Madrid. While acknowledging the significance of social networks, economic interest, and party politics, it instead focuses on the identity characteristics, both those of the newcomers and their host societies, in determining the exclusion and inclusion that different ethnic communities face. Further, the article examines how the host society’s inclusion-exclusion dynamics interact with the immigrants’ own perceptions of belonging or isolation to produce certain political, economic, and social integration outcomes. The argument is explored for Poles and Nigerians in Dublin and Bulgarians and Ecuadorians in Madrid

    Factors affecting breeding success of the Flea Bay white-flippered penguin (Eudyptula minor albosignata) colony

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    The little blue penguin (Eudyptula minor) is in decline throughout much of its range in New Zealand and Australia, largely due to introduced predators, human disturbance and roadkill mortalities. The whiteflippered penguin is a unique morphological variant of the blue penguin, which is traditionally given subspecific status (Eudyptula minor albosignata), and is found only on Banks Peninsula and Motunau Island in Canterbury, New Zealand. We monitored a varying number of nest boxes from 1996 to 2009. Overall breeding success was 64% over 13 years of monitoring, with a hatching success rate of 75% and a fledging success rate of 85%. We used a set of generalised linear mixed models and model selection to examine the relative influence of various explanatory variables on hatching, fledging and overall breeding success. Breeding success in nest boxes significantly increased with shorter average pair bond length, longer guard period and later relative lay date. Guard period length was the best predictor of breeding success, followed by relative lay date and average pair bond length. Hatching success also increased with later relative lay date but fledging success was not influenced by any of the explanatory variables measured

    Translocations of North Island kokako, 1981-2011

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    The North Island kokako (Callaeas wilsoni) is a threatened endemic passerine whose distribution has declined greatly on the New Zealand mainland due primarily to predation by ship rats (Rattus rattus) and brushtail possums (Trichosurus vulpecula). It persists in 21 populations, of which 10 (48%) have been established by translocation, and 1 has been supplemented by translocation. Of the 11 populations subject to translocation, 4 are on islands and the remainder are on the mainland; 7 translocations have resulted in successful new or supplemented populations and another 4 translocations are in progress. Translocations to another 5 sites did not establish breeding populations for various reasons. In total, there were 94 translocations of 286 kokako to the 16 sites, and the number released at a site averaged 18 (range 3-33) birds. Kokako were released at a site over an average period of 49 months (range 1-159 months) with a mean of 3 birds (maximum 10) released per day. The small numbers of kokako released and the long time required to complete a translocation were due to the difficulty and high expense of catching kokako. Translocations will continue to be important for the conservation of this species, to establish further new populations and to limit inbreeding depression and allele loss in existing populations

    Identity Politics in Local Markets: Comparing Immigrant Integration Outcomes in the ‘New’ Europe

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    Thesis advisor: Gerald M. EasterThis dissertation explores the factors that influence immigrant reception and integration in new immigration spaces like Dublin and Madrid. Through the case studies of Poles and Nigerians in Dublin and Ecuadorians and Bulgarians in Madrid, the thesis provides a response to three research questions: 1) How do Western European receiving societies construct inclusion and exclusion of the immigrant?; 2) Why do immigrants belong or fail to fit in?; 3) How do inclusion-exclusion dynamics and immigrants’ perceptions affect incorporation outcomes? The project contributes to migration scholarship by emphasizing the understudied cultural and local aspects of incorporation and bringing immigrant agency back into the integration equation. The central argument is that culture and identity matter. While acknowledging the significance of material self-interest, social contact, or national policy regimes, the dissertation finds that identity characteristics, both those of the newcomers and their host societies, are primary in determining the welcome or rejection of different ethnic communities in receiving cities. Further, the study shows that migrants are agents who form their own perceptions of belonging or isolation on the basis of cultural identity. These perceptions determine the foreigners’ stake in the host context and what they do with the openings and closures they face. The thesis concludes that political, economic, and social incorporation outcomes are ultimately conditioned on the interplay between the inclusion-exclusion dynamics in the receiving context and the immigrants’ perceptions of welcome or rejection. Analysis of in-depth interviews, survey data, and relevant documents and legislation for all four case studies confirms the main argument. The comparison among European and non-European immigrants in Dublin and Madrid attests to the significance of culture and identity for integration outcomes and contributes to the broader understanding of immigrant incorporation in Europe and beyond.Thesis (PhD) — Boston College, 2015.Submitted to: Boston College. Graduate School of Arts and Sciences.Discipline: Political Science

    Solving the Random Pielou Logistic Equation with the Random Variable Transformation Technique: Theory and Applications

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    [EN] The study of the dynamics of the size of a population via mathematical modelling is a problem of interest and widely studied. Traditionally, continuous deterministic methods based on differential equations have been used to deal with this problem. However, discrete versions of some models are also available and sometimes more adequate. In this paper, we randomize the Pielou logistic equation in order to include the inherent uncertainty in modelling. Taking advantage of the method of transformation of random variables, we provide a full probabilistic description to the randomized Pielou logistic model via the computation of the probability density functions of the solution stochastic process, the steady state, and the time until a certain level of population is reached. The theoretical results are illustrated by means of two examples: The first one consists of a numerical experiment and the second one shows an application to study the diffusion of a technology using real data.This work has been partially supported by the Ministerio de EconomĂ­a y Competitividad grant MTM2017-89664-PCortĂ©s, J.; Navarro-Quiles, A.; Romero, J.; RosellĂł, M. (2019). Solving the Random Pielou Logistic Equation with the Random Variable Transformation Technique: Theory and Applications. Mathematical Methods in the Applied Sciences. 42(17):5708-5717. https://doi.org/10.1002/mma.5440S570857174217Kwasnicki, W. (2013). Logistic growth of the global economy and competitiveness of nations. Technological Forecasting and Social Change, 80(1), 50-76. doi:10.1016/j.techfore.2012.07.007Chen-Charpentier, B. M., & Stanescu, D. (2011). Biofilm growth on medical implants with randomness. Mathematical and Computer Modelling, 54(7-8), 1682-1686. doi:10.1016/j.mcm.2010.11.075Wolfram Research Inc.Mathematica. Version 11.2 Champaign IL;2018.CNMC ComisiĂłn Nacional de los Mercados y la Competencia.http://data.cnmc.es/datagraph/jsp/inf_anual.jsp Accessed: 2018‐07‐24 (in Spanish)

    Competition between species can stabilize public-goods cooperation within a species

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    Competition between species is a major ecological force that can drive evolution. Here, we test the effect of this force on the evolution of cooperation within a species. We use sucrose metabolism of budding yeast, Saccharomyces cerevisiae, as a model cooperative system that is subject to social parasitism by cheater strategies. We find that when cocultured with a bacterial competitor, Escherichia coli, the frequency of cooperator phenotypes in yeast populations increases dramatically as compared with isolated yeast populations. Bacterial competition stabilizes cooperation within yeast by limiting the yeast population density and also by depleting the public goods produced by cooperating yeast cells. Both of these changes induced by bacterial competition increase the cooperator frequency because cooperator yeast cells have a small preferential access to the public goods they produce; this preferential access becomes more important when the public good is scarce. Our results indicate that a thorough understanding of species interactions is crucial for explaining the maintenance and evolution of cooperation in nature.United States. National Institutes of Health (GM085279‐02)National Science Foundation (U.S.) (PHY‐1055154)Alfred P. Sloan Foundation (BR2011‐066

    A probabilistic analysis of a Beverton-Holt type discrete model: Theoretical and computing analysis

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    "This is the peer reviewed version of the following article: CortĂ©s, J-C, Navarro-Quiles, A, Romero, J-V, RosellĂł, M-D. A probabilistic analysis of a Beverton-Holt type discrete model: Theoretical and computing analysis. Comp and Math Methods. 2019; 1:e1013, which has been published in final form at https://doi.org/10.1002/cmm4.1013. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving."[EN] In this paper a randomized version of the Beverton-Holt type discrete model is proposed. Its solution stochastic process and the random steady state are determined. Its first probability density function and second probability density function are obtained by means of the random variable transformation method, providing a full probabilistic description of the solution. Finally, several numerical examples are shown.This work has been partially supported by the Ministerio de EconomĂ­a, Industria y Competitividad under grant MTM2017-89664-P. The authors express their deepest thanks and respect to the editors and reviewers for their valuable comments.CortĂ©s, J.; Navarro-Quiles, A.; Romero, J.; RosellĂł, M. (2019). A probabilistic analysis of a Beverton-Holt type discrete model: Theoretical and computing analysis. Computational and Mathematical Methods. 1(1):1-12. https://doi.org/10.1002/cmm4.1013S11211Kwasnicki, W. (2013). Logistic growth of the global economy and competitiveness of nations. Technological Forecasting and Social Change, 80(1), 50-76. doi:10.1016/j.techfore.2012.07.007De la Sen, M. (2008). The generalized Beverton–Holt equation and the control of populations. Applied Mathematical Modelling, 32(11), 2312-2328. doi:10.1016/j.apm.2007.09.007CortĂ©s, J.-C., Navarro-Quiles, A., Romero, J.-V., & RosellĂł, M.-D. (2018). Computing the probability density function of non-autonomous first-order linear homogeneous differential equations with uncertainty. Journal of Computational and Applied Mathematics, 337, 190-208. doi:10.1016/j.cam.2018.01.015CasabĂĄn, M.-C., CortĂ©s, J.-C., Navarro-Quiles, A., Romero, J.-V., RosellĂł, M.-D., & Villanueva, R.-J. (2017). Computing probabilistic solutions of the Bernoulli random differential equation. Journal of Computational and Applied Mathematics, 309, 396-407. doi:10.1016/j.cam.2016.02.034CortĂ©s, J.-C., Navarro-Quiles, A., Romero, J.-V., & RosellĂł, M.-D. (2017). Randomizing the parameters of a Markov chain to model the stroke disease: A technical generalization of established computational methodologies towards improving real applications. Journal of Computational and Applied Mathematics, 324, 225-240. doi:10.1016/j.cam.2017.04.040CortĂ©s, J.-C., Navarro-Quiles, A., Romero, J.-V., & RosellĂł, M.-D. (2017). Full solution of random autonomous first-order linear systems of difference equations. Application to construct random phase portrait for planar systems. Applied Mathematics Letters, 68, 150-156. doi:10.1016/j.aml.2016.12.01

    Detection of six serotypes of botulinum neurotoxin using fluorogenic reporters

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    Methods that do not require animal sacrifice to detect botulinum neurotoxins (BoNTs) are critical for BoNT antagonist discovery and the advancement of quantitative assays for biodefense and pharmaceutical applications. Here we describe the development and optimization of fluorogenic reporters that detect the proteolytic activity of BoNT/A, B, D, E, F, and G serotypes in real time with femtomolar to picomolar sensitivity. Notably, the reporters can detect femtomolar concentrations of BoNT/A in 4 h and BoNT/E in 20 h, sensitivity that equals that of animal-based methods. The reporters can be used to determine the specific activity of BoNT preparations with intra- and inter-assay coefficients of variation of approximately 10%. Finally, we find that the greater sensitivity of our reporters compared with those used in other commercially available assays makes the former attractive candidates for high-throughput screening of BoNT antagonists
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