434 research outputs found
The effects of colony dynamics and climate on a declining population of sociable weavers, Phlietairus Socius
No full textDT-MODELS
No full text<p>The code required to reproduce the simulation analysis in: Priyadarshani, D., Altwegg, R., Lee, A. T. K., & Hwang, W. H. (2022). What can occupancy models gain from time-to-detection data? Ecology.</p>
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<p><strong>Run the simulation analysis</strong></p>
<p><code>R_code_for_Simulation_Study.R</code> is the primary code file to run the simulation analysis.</p>
<p><code>R_code_for_Data_Analysis.R</code> is the code for Karoo data analysis. </p>
<p><code>R_code_for_RE_Comparison.R </code>is the code for efficiency comparison TTD vs DND (Figure 1).</p>
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Identification of the ECR zone in the SWISSCASE ECR ion source
No full textThe magnetic field of the permanent mag-net electron cyclotron resonance (ECR) ion source SWISSCASE located at the Univer-sity of Bern has been numerically simu-lated and experimentally investigated. For the first time the magnetized volume quali-fied for electron cyclotron resonance at 10.88 GHz and 388.6 mT has been analyzed in highly detailed 3D simulations with unprece-dented resolution. The observed pattern of carbon coatings on the source correlates strongly with the electron and ion distribu-tion in the ECR plasma of SWISSCASE. Un-der certain plasma conditions the ion distri-bution is tightly bound to the electron dis-tribution and can considerably simplify the numerical calculations in ECR related appli-cations such as ECR ion engines and ECR ion implanters. 1 Indroduction The reliable and stable operation of an Electron Cyclotron Resonance (ECR) ion source in produc-ing high intensity beams of highly charged ions depends on the successful design of the magnetic confinement. This confinement enables the ECR process and is responsible for the confinement of high energy electrons for the production of highly charged ions. The resonance criteria for the ECR process is given by Eq. (1) [1, 2, 4]
Distributed glycine in comet 67P/Churyumov-Gerasimenko
No full textMost of the gaseous molecules that are detected in cometary atmospheres are produced through sublimation of nucleus ices. Distributed sources may also occur, that is, production within the coma, from the solid component of dust particles that are ejected from the nucleus. Glycine, the simplest amino acid, was observed episodically in the atmosphere of comet 67P/Churyumov-Gerasimenko (67P) by the ROSINA mass spectrometer on board the Rosetta probe. A series of measurements on 28 March 2015 revealed a distributed density profile at between 14 and 26 km away from the nucleus. We here present and discuss three study cases: (i) glycine emitted directly and only from the nucleus, (ii) glycine emitted from the sublimation of solid-state glycine on the dust particles that are ejected from the nucleus, and (iii) glycine molecules embedded in water ice that are emitted from the sublimation of this ice from the dust particles that are ejected from the nucleus. A numerical model was developed to calculate the abundance of glycine in the atmosphere of comet 67P as a function of the distance from the nucleus, and to derive its initial abundance in the lifted dust particles. We show that a good fit to the observations corresponds to a distributed source of glycine that is embedded in sublimating water ice from dust particles that are ejected from the nucleus (iii). The few hundred ppb of glycine embedded in water ice on dust particles (nominally 170 ppb by mass) agree well with the observed distribution
A ~ 32-70 K formation temperature range for the ice grains agglomerated by Comet 67P/Churyumov-Gerasimenko
No full textGrand Canonical Monte Carlo simulations are used to reproduce the N₂/CO ratio ranging between 1.7 x 10⁻³ and 1.6 x 10⁻² observed in situ in the Jupiter-family comet 67 P/Churyumov-Gerasimenko (67 P) by the ROSINA mass spectrometer on board the Rosetta spacecraft. By assuming that this body has been agglomerated from clathrates in the protosolar nebula (PSN), simulations are developed using elaborated interatomic potentials for investigating the temperature dependence of the trapping within a multiple-guest clathrate formed from a gas mixture of CO and N₂ in proportions corresponding to those expected for the PSN. By assuming that 67 P agglomerated from clathrates, our calculations suggest the cometary grains must have been formed at temperatures ranging between ~ 31.8 and 69.9 K in the PSN to match the N₂/CO ratio measured by the ROSINA mass spectrometer. The presence of clathrates in Jupiter-family comets could then explain the potential N₂ depletion (factor of up to ~ 87 compared to the protosolar value) measured in 67 P/Churyumov-Gerasimenko
Trait-dependent occupancy dynamics of birds in temperate forest landscapes: fine-scale observations in a hierarchical multi-species framework
No full textSilvicultural practices lead to changes in forest composition and structure and may impact species diversity from the overall regional species pool to stand-level species occurrence. We explored to what extent fine-scale occupancy patterns in differently managed forest stands are driven by environment and ecological traits in three regions in Germany using a multi-species hierarchical model. We tested for the possible impact of environmental variables and ecological traits on occupancy dynamics in a joint modelling exercise while taking possible variation in coefficient estimates over years and plots into account. Bird species richness differed across regions and years, and trends in species richness across years were different in the three regions. On the species level, forest management affected occupancy of species in all regions, but only 3–5% of the total assemblage-level variation in occurrence probability was explained by either forest type and successional stage and < 1% by forest edge. On the assemblage level, bird occurrence decreased with body mass in all regions. Species with smaller breeding ranges had lower occurrence probabilities in one region, while later spring arrival decreased occurrence probabilities in the two other regions. Spatial variation in the effect size of trait covariates such as species phylogeny and breeding strata showed that variation in patch occupancy due to fine-scale differences in forest management is, to some extent, predictable from ecological traits. Our results show that environmental factors and ecological traits jointly predict variation in bird occupancy patterns and their response to forest management. Observations at the fine scale of forest stands, at which conservation efforts can be arranged along with forest management practices in heterogeneous environments, have been shown to provide meaningful insights despite the difficulties involved in monitoring mobile organisms such as birds at the plot level.K. Wells, R. B. O'Hara, S. M. Böhm, S. Gockel, A. Hemp, S. C. Renner, S. Pfeiffer, K. Böhning-Gaese, and E. K. V. Kalk
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