434 research outputs found
Kleptoparasitic Hawk-Dove Games
The Hawk-Dove game is a classical game-theoretical model of potentially aggressive animal conflicts. In this paper, we apply game theory to a population of foraging animals that may engage in stealing food from one another. We assume that the population is composed of two types of individuals, Hawks and Doves. Hawks try to escalate encounters into aggressive contests while Doves engage in non-aggressive displays between themselves or concede to aggressive Hawks. The fitness of each type depends upon various natural parameters, such as food density, the mean handling time of a food item, as well as the mean times of conflicts over the food. We find the Evolutionarily Stable States (ESSs) for all parameter combinations and show that there are two possible ESSs, pure Hawks, or a mixed population of Hawks and Doves. We demonstrate that for any set of parameter values there is exactly one ESS
Análisis de diagnóstico de situación de prioridades de desarrollo y dinámicas del sistema agroalimentario de las zonas altoandinas en contexto de una agricultura con bajas emisiones
El estudio se centra en el análisis diagnóstico de la situación de las prioridades de desarrollo y las dinámicas del sistema agroalimentario de las zonas altoandinas en el contexto de una agricultura con bajas emisiones. La agricultura es el principal impulsor de la deforestación tropical y contribuye significativamente a las emisiones antropogénicas totales de gases de efecto invernadero. En la región andina, la actividad agrícola en condiciones de secano, que es la que practican la mayoría de pequeños productores, es una de las más sensibles a los cambios climáticos. El estudio tiene como objetivo realizar un mapeo de actores e identificar las prioridades de desarrollo sostenible a nivel local en distritos agrícolas de los Andes peruanos. También busca identificar las necesidades y desafíos que representa el cambio climático para los productores agrícolas en dichas zonas y analizar las dinámicas del sistema agroalimentario para identificar puntos de intervención para mejorar la competitividad con bajas emisiones.
El estudio se centra en los Andes del Norte y los Andes Centrales del Perú. En los Andes del Norte, se examinan los distritos de Chugay y Pataz, que forman parte de la provincia de Sánchez Carrión en el departamento de La Libertad. En los Andes Centrales, se analizan los distritos de Quilcas y Yauli. El estudio utiliza una combinación de grupos focales y encuestas a productores para recopilar datos. También se realiza un análisis de actores de sistemas agroalimentarios locales y se priorizan los objetivos de desarrollo sostenible a nivel local.
El estudio proporciona una caracterización de los productores encuestados en los Andes del Norte y del Centro, así como un análisis de los actores en los distritos de estudio. También se realiza una descripción de los sistemas agroalimentarios y un análisis de las dinámicas de estos sistemas. Discusiones y conclusiones: El estudio concluye que es importante entender las opciones de desarrollo con bajas emisiones para el desarrollo sostenible del país, desde el punto de vista de actores a diferentes escalas. Se sugiere que las iniciativas para combinar instrumentos de política pueden contribuir a la conservación de los pastizales y bofedales en la zona Andina y reducir las emisiones no solo en la zona altoandina sino evitar la migración a bosques amazónicos donde las emisiones son más altas
Biomagnifcation and body distribution of ivermectin in dung beetles
We thank the staf of Doñana Biological Reserve (DBR-ICTS), Doñana National Park, and Los Alcornocales
Natural Park, especially D. Paz, F. Ibáñez, P. Bayón, M. Malla and D. Ruiz for logistic facilities for the field
work and permissions (2019107300000904/IRM/MDCG/mes) to collect cattle dung and dung beetles. We
are grateful to J. Castro and A. Rascón for technical assistance. We also thank A. V. Giménez-Gómez for her
technical assistance in the laboratory work. We thank also F.-T Krell and the two anonymous reviewers for their
constructive comments. Financial support was provided by the project CGL2015-68207-R of the Secretaría de
Estado de Investigación–Ministerio de Economía y Competitividad.A terrestrial test system to investigate the biomagnifcation potential and tissue-specifc distribution
of ivermectin, a widely used parasiticide, in the non-target dung beetle Thorectes lusitanicus (Jekel)
was developed and validated. Biomagnifcation kinetics of ivermectin in T. lusitanicus was investigated
by following uptake, elimination, and distribution of the compound in dung beetles feeding on
contaminated faeces. Results showed that ivermectin was biomagnifed in adults of T. lusitanicus
when exposed to non-lethal doses via food uptake. Ivermectin was quickly transferred from the gut to
the haemolymph, generating a biomagnifcation factor (BMFk) three times higher in the haemolymph
than in the gut after an uptake period of 12 days. The fat body appeared to exert a major role on
the biomagnifcation of ivermectin in the insect body, showing a BMFk 1.6 times higher than in the
haemolymph. The results of this study highlight that the biomagnifcation of ivermectin should be
investigated from a global dung-based food web perspective and that the use of these antiparasitic
substances should be monitored and controlled on a precautionary basis. Thus, we suggest that an
additional efort be made in the development of standardised regulatory recommendations to guide
biomagnifcation studies in terrestrial organisms, but also that it is necessary to adapt existing methods
to assess the efects of such veterinary medical products
The Pierre Auger Observatory III: Other Astrophysical Observations
Astrophysical observations of ultra-high-energy cosmic rays with the Pierre
Auger ObservatoryComment: Contributions to the 32nd International Cosmic Ray Conference,
Beijing, China, August 201
Highlights from the Pierre Auger Observatory
The Pierre Auger Observatory is the world's largest cosmic ray observatory.
Our current exposure reaches nearly 40,000 km str and provides us with an
unprecedented quality data set. The performance and stability of the detectors
and their enhancements are described. Data analyses have led to a number of
major breakthroughs. Among these we discuss the energy spectrum and the
searches for large-scale anisotropies. We present analyses of our X
data and show how it can be interpreted in terms of mass composition. We also
describe some new analyses that extract mass sensitive parameters from the 100%
duty cycle SD data. A coherent interpretation of all these recent results opens
new directions. The consequences regarding the cosmic ray composition and the
properties of UHECR sources are briefly discussed.Comment: 9 pages, 12 figures, talk given at the 33rd International Cosmic Ray
Conference, Rio de Janeiro 201
Anisotropy and chemical composition of ultra-high energy cosmic rays using arrival directions measured by the Pierre Auger Observatory
The Pierre Auger Collaboration has reported evidence for anisotropy in the
distribution of arrival directions of the cosmic rays with energies
eV. These show a correlation with the distribution
of nearby extragalactic objects, including an apparent excess around the
direction of Centaurus A. If the particles responsible for these excesses at
are heavy nuclei with charge , the proton component of the
sources should lead to excesses in the same regions at energies . We here
report the lack of anisotropies in these directions at energies above
(for illustrative values of ). If the anisotropies
above are due to nuclei with charge , and under reasonable
assumptions about the acceleration process, these observations imply stringent
constraints on the allowed proton fraction at the lower energies
Operations of and Future Plans for the Pierre Auger Observatory
Technical reports on operations and features of the Pierre Auger Observatory,
including ongoing and planned enhancements and the status of the future
northern hemisphere portion of the Observatory. Contributions to the 31st
International Cosmic Ray Conference, Lodz, Poland, July 2009.Comment: Contributions to the 31st ICRC, Lodz, Poland, July 200
Measurement of the Depth of Maximum of Extensive Air Showers above 10^18 eV
We describe the measurement of the depth of maximum, Xmax, of the
longitudinal development of air showers induced by cosmic rays. Almost four
thousand events above 10^18 eV observed by the fluorescence detector of the
Pierre Auger Observatory in coincidence with at least one surface detector
station are selected for the analysis. The average shower maximum was found to
evolve with energy at a rate of (106 +35/-21) g/cm^2/decade below 10^(18.24 +/-
0.05) eV and (24 +/- 3) g/cm^2/decade above this energy. The measured
shower-to-shower fluctuations decrease from about 55 to 26 g/cm^2. The
interpretation of these results in terms of the cosmic ray mass composition is
briefly discussed.Comment: Accepted for publication by PR
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