On the principle of competitive exclusion in metapopulation models

In this paper we present and analyse a simple two populations model with migrations among two different environments. The populations interact by competing for resources. Equilibria are investigated. A proof for the boundedness of the populations is provided. A kind of competitive exclusion principle for metapopulation systems is obtained. At the same time we show that the competitive exclusion principle at the local patch level may be prevented to hold by the migration phenomenon, i.e. two competing populations may coexist, provided that only one of them is allowed to freely move or that migrations for both occur just in one direction

Effects of Ground-State Correlations on High Energy Scattering off Nuclei: the Case of the Total Neutron-Nucleus Cross Section

With the aim at quantitatively investigating the longstanding problem concerning the effect of short range nucleon-nucleon correlations on scattering processes at high energies, the total neutron-nucleus cross section is calculated within a parameter-free approach which, for the first time, takes into account, simultaneously, central, spin, isospin and tensor nucleon-nucleon (NN) correlations, and Glauber elastic and Gribov inelastic shadowing corrections. Nuclei ranging from 4He to 208Pb and incident neutron momenta in the range 3 GeV/c - 300 GeV/c are considered; the commonly used approach which approximates the square of the nuclear wave function by a product of one-body densities is carefully analyzed, showing that NN correlations can play a non-negligible role in high energy scattering off nuclei.Comment: 5 pages, 3 figure

Comparison of the Results of Analytical and Numerical Models of Pre-Reinforcement in Shallow Tunnels

AbstractThe steel pipe umbrella is a widely used technology when tunnelling in weak soils in order to create pre-support ahead of the tunnel face. The design of steel pipes is frequently done through simplified analytical approaches which are easy to apply but require proper assessment of the loads acting on the pipe. To provide information on this key design aspect, the results of the comparison between a three-dimensional numerical model developed with the code FLAC 3D and an analytical model based on the approach of a beam on yielding supports is presented and discussed. The comparison refers to a shallow tunnel with an overburden of three times its diameter for two different types of weak rock masses. The obtained results provide suggestions about the load that has to be applied in the analytical model for the design phase

2018 Watermelon Variety Evaluation in Indiana

This is a compilation of 20 research trial reports from four land-grant universities in the Midwestern United States. Crops include cantaloupe, pickling cucumber, pepper, potato, pumpkin, summer squash and zucchini, sweet corn, tomato, and watermelon. Somecrops were evaluated in high tunnels or hoophouses. Most trials evaluated different cultivars or varieties. One report addressed plant spacing for sweet corn and one addressed soil block for production of tomato seedlings. A list of vegetable seed sources and a list of other online sources of vegetable trial reports are also included

Prevalence of periodontitis in adults aged 40 to 80 years in Metropolitan Lima, 2024. Self-report

Los cuidados de la salud y la prevención de la caries han generado que la vida media alcance más personas con edades más avanzadas y con la presencia de piezas dentarias por lo que la prevalencia de la periodontitis puede verse incrementada. Los estudios de prevalencia de periodontitis, son costosos y demandan de personal muy calificado, por lo que se tiene escasez de estudios epidemiológicos en muchas regiones. El objetivo del presente estudio: será determinar la prevalencia autoreportada de la periodontitis en adultos de 40 a 80 años en Lima Metropolitana. Materiales y métodos: Se aplicará el cuestionario de ocho preguntas de autoreporte validado en estudios de prevalencia de periodontitis en Estados Unidos, en veinte distritos de Lima Metropolitana, cuyos participantes serán invitados a Charlas de Salud Oral en cada Municipalidad. Resultados esperados: Se espera una mayor prevalencia de periodontitis conforme la edad aumenta, asimismo esta será mayor en el sexo masculino. Conclusiones: A mayor edad la periodontitis es más prevalente significativamente. Es importante tomar en cuenta que los adultos mayores tendrán mayor necesidad de diagnosticar la periodontitis.Health care and caries prevention have caused the average life span to reach more people with more advanced ages and with the presence of teeth, so the prevalence of periodontitis may be increased. Periodontitis prevalence studies are expensive and require highly qualified personnel, so there is a shortage of epidemiological studies in many regions. The objective of the present study: will be to determine the self-reported prevalence of periodontitis in adults aged 40 to 80 years in Metropolitan Lima. Materials and methods: The eight-question self-report questionnaire validated in periodontitis prevalence studies in the United States will be applied in twenty districts of Metropolitan Lima, whose participants will be invited to Oral Health Talks in each Municipality. Expected results: A higher prevalence of periodontitis is expected as age increases, and this will also be higher in the male sex. Conclusions: The older the age, the more prevalent periodontitis is. It is important to note that older adults will have a greater need to diagnose periodontitis

TRY plant trait database - enhanced coverage and open access

Plant traits-the morphological, anatomical, physiological, biochemical and phenological characteristics of plants-determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait-based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits-almost complete coverage for 'plant growth form'. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait-environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives