Implementing spatially explicit wind-driven seed and pollen dispersal in the individual-based larch simulation model: LAVESI-WIND 1.0

It is of major interest to estimate the feedback of arctic ecosystems to the global warming we expect in upcoming decades. The speed of this response is driven by the potential of species to migrate, tracking their climate optimum. For this, sessile plants have to produce and disperse seeds to newly available habitats, and pollination of ovules is needed for the seeds to be viable. These two processes are also the vectors that pass genetic information through a population. A restricted exchange among subpopulations might lead to a maladapted population due to diversity losses. Hence, a realistic implementation of these dispersal processes into a simulation model would allow an assessment of the importance of diversity for the migration of plant species in various environments worldwide. To date, dynamic global vegetation models have been optimized for a global application and overestimate the migration of biome shifts in currently warming temperatures. We hypothesize that this is caused by neglecting important fine-scale processes, which are necessary to estimate realistic vegetation trajectories. Recently, we built and parameterized a simulation model LAVESI for larches that dominate the latitudinal treelines in the northernmost areas of Siberia. In this study, we updated the vegetation model by including seed and pollen dispersal driven by wind speed and direction. The seed dispersal is modelled as a ballistic flight, and for the pollination of ovules of seeds produced, we implemented a wind-determined and distance-dependent probability distribution function using a von Mises distribution to select the pollen donor. A local sensitivity analysis of both processes supported the robustness of the model's results to the parameterization, although it highlighted the importance of recruitment and seed dispersal traits for migration rates. This individual-based and spatially explicit implementation of both dispersal processes makes it easily feasible to inherit plant traits and genetic information to assess the impact of migration processes on the genetics. Finally, we suggest how the final model can be applied to substantially help in unveiling the important drivers of migration dynamics and, with this, guide the improvement of recent global vegetation models.</p

Double infection with a resistant and a multidrug-resistant strain of Mycobacterium tuberculosis.

An immunocompetent patient was dually infected with a resistant and a multidrug-resistant strain of Mycobacterium tuberculosis (TB). The multidrug-resistant strain, which belongs to the W- strain/Beijing family, was first isolated after 3 months of therapy. Inappropriate treatment led to further drug resistance and unsuccessful therapy. Thus, additional infections with resistant M. tuberculosis strains should be considered when tuberculosis therapy fails

Provenance of Cambro-Ordovician siliciclastic rocks of the SW Iberia: insights to the evolution of North Gondwana margin.

This study makes a comparison between the populations of detrital zircon of the Cambrian sandstones from the Ossa-Morena Zone (OMZ) and the Ordovician quartzites from the southern domains of the Central Iberian Zone (S-CIZ) in order to identify the sources during development of North Gondwana basins (SW Iberia). The U-Pb results obtained for the Lower Cambrian sandstones of the OMZ show a remarkable similarity with the detrital zircon ages of greywackes from the underlying OMZ Ediacaran basement (Série Negra Succession). However, there is a greater proportion of the Cryogenian grains in the Cambrian rocks which main sources are: i) the Late Cadomian magmatic arcs (Ediacaran, ca. 635-545 Ma) which also contributed to infill the Late Ediacaran basins of the OMZ; and ii) the Early Cadomian arcs ( Cryogenian, ca. 700-635 Ma). In the Lower Ordovician quartzites of the S-CIZ (Armorican and Sarnelha formations) the age distribution of detrital zircons overlaps the population of detrital zircons of the underlying S-CIZ Ediacaran basement (Beiras Group). Nevertheless, there are some differences in the Sarnelhas quartzites which have a population of detrital zircons similar to those of the Ediacaran greywackes and Cambrian sandstones of the OMZ. The Cambrian grains found in the Lower Ordovician quartzites fit the ages of magmatism representing the onset of rifting in North Gondwana that occurs in the OMZ and is absent in the S-CIZ. The Lower Ordovician grains are probably related to the magmatic event that preceded the passive margin stage of the Rheic Ocean, and exist in the CIZ and OMZ

Provenance analysis of the Late Ediacaran basins from SW Iberia (Serie Negra Succession and Beiras Group): Evidence for a common Neoproterozoic evolution

This study makes a comparison of the populations of detrital zircon from Late Ediacaran greywackes of the Ossa-Morena Zone (OMZ) and the southern domains of the Central Iberian Zone (S-CIZ). The results obtained reveal that the main difference between the age spectra of both populations of detrital zircon is the Neoproterozoic, in particularly the Cryogenian grains. Our new data suggest that deposition in both CIZ and OMZ Ediacaran basins was coeval and shows a long lived magmatic event typical of the northern Gondwana margin (Avalonian–Cadomian belt and Pan-African belt). Overall, SW Iberia shows the following sequence of Cryogenian and Ediacaran zircon-forming events: i) ca. 850–700 Ma, Pan-African suture (well represented in the Beiras Group and in the Mares Formation of the Serie Negra Succession); ii) ca. 700-635 Ma, Early Cadomian arc (dominant in the Beiras Group and in the Mares Formation of the Serie Negra Succession); and iii) ca. 635-545 Ma, Late Cadomian arc (the most important in the Mosteiros and Escoural formations of the Serie Negra Succession). The obtained results reinforce that the Late Ediacaran basins of SW Iberia were evolved together in the active margin of North-Gondwana in the same paleogeographic scenario but sufficiently separated to justify the differences mainly identified in their Neoproterozoic detrital zircon contents. This finding shows that there is no apparent reason to believe that the boundary between the OMZ and the S-CIZ marks a Cadomian suture

Heterogeneous microstructures tuned in a high throughput architecture

A new method applied to the sensor proposed by Zhang et al. in 2018 is demonstrated in this paper that combines the benefits of this design with the fast heating possible with nanocalorimetry. By applying a PID regulated pulse instead of a constant wattage, we unlock an accessible method to sense morphological changes occurring over short time periods that would be invisible to methods based only on heat capacity. In this study, multilayer Ni/Al thin films were linearly heated at 25, 50, 100, and 200 K/s to over 700°C, showing two distinct peaks in resistance change with activation energies of 554 and 747 kJ/mol, respectively. Through Scanning Transmission Electron Microscopy (STEM) and Energy Dispersive X-ray Analysis (EDX) analysis on cross sections taken ex situ from samples quenched before and after the peaks of interest, we find strong evidence that peak 1 corresponds to Ni diffusing through Al grain boundaries forming intermetallic phases that essentially block the highly conductive Al pathway. This presents the potential to design and calibrate novel heterogeneous structures in a high throughput manner

Global organization of metabolic fluxes in the bacterium, Escherichia coli

Cellular metabolism, the integrated interconversion of thousands of metabolic substrates through enzyme-catalyzed biochemical reactions, is the most investigated complex intercellular web of molecular interactions. While the topological organization of individual reactions into metabolic networks is increasingly well understood, the principles governing their global functional utilization under different growth conditions pose many open questions. We implement a flux balance analysis of the E. coli MG1655 metabolism, finding that the network utilization is highly uneven: while most metabolic reactions have small fluxes, the metabolism's activity is dominated by several reactions with very high fluxes. E. coli responds to changes in growth conditions by reorganizing the rates of selected fluxes predominantly within this high flux backbone. The identified behavior likely represents a universal feature of metabolic activity in all cells, with potential implications to metabolic engineering.Comment: 15 pages 4 figure