Faint dwarfs as a test of DM models: WDM vs. CDM

We use high resolution Hydro$+$N-Body cosmological simulations to compare the assembly and evolution of a small field dwarf (stellar mass ~ 10$^{6-7}$ M$\odot$, total mass 10$^{10}$ M$\odot$ in $\Lambda$ dominated CDM and 2keV WDM cosmologies. We find that star formation (SF) in the WDM model is reduced and delayed by 1-2 Gyr relative to the CDM model, independently of the details of SF and feedback. Independent of the DM model, but proportionally to the SF efficiency, gas outflows lower the central mass density through `dynamical heating', such that all realizations have circular velocities $<$ 20kms at 500$~$pc, in agreement with local kinematic constraints. As a result of dynamical heating, older stars are less centrally concentrated than younger stars, similar to stellar population gradients observed in nearby dwarf galaxies. Introducing an important diagnostic of SF and feedback models, we translate our simulations into artificial color-magnitude diagrams and star formation histories in order to directly compare to available observations. The simulated galaxies formed most of their stars in many $\sim$10 Myr long bursts. The CDM galaxy has a global SFH, HI abundance and Fe/H and alpha-elements distribution well matched to current observations of dwarf galaxies. These results highlight the importance of directly including `baryon physics' in simulations when 1) comparing predictions of galaxy formation models with the kinematics and number density of local dwarf galaxies and 2) differentiating between CDM and non-standard models with different DM or power spectra.Comment: 13 pages including Appendix on Color Magnitude Diagrams. Accepted by MNRAS. Added one plot and details on ChaNGa implementation. Reduced number of citations after editorial reques

Stable isotopes reveal the importance of seabirds and marine foods in the diet of St Kilda field mice

Introduced mammals have devastated island nesting seabird populations worldwide. Declines in breeding seabirds on St Kilda, UK, have been linked to climate change and predation from great skuas Stercorarius skuas, but the introduced St Kilda field mouse Apodemus sylvaticus hirtensis may also play a role by feeding on adults, chicks or eggs. Here, we use stable isotopes in St Kilda mouse blood and potential dietary items to investigate their foraging ecology, specifically focussing on the importance of seabirds and marine foods in their diet. Mice were seasonally sampled at three sites on Hirta, St Kilda over three consecutive years (2010–2012). The δ13C and δ15N ratios were used in analyses, including isotope niche and dietary source mixing models, to examine foraging behaviour among locations and between seabird breeding seasons. Mice sampled in Carn Mor – where the majority of the island’s seabirds nest - had consistently higher δ13C than other locations throughout the year, with δ15N also being significantly higher for all but one comparison. The isotopic niche width (SEAs) of Carn Mor mice in each season were distinct from the other locations, and became smaller during the seabird breeding season. Dietary mixing models revealed that seabirds made up a large proportion of the diet for mice from Carn Mor, particularly during the seabird breeding season. In conclusion, our work reveals that seabird-derived foods are likely to form a significant part of the diet of St Kilda mice populations located in and around breeding colonies. It is unclear however, whether this is from scavenging or predation of seabirds, or through their discarded food items. Given that mice have had significant effects on seabird populations elsewhere, it is important to carry out further work to determine whether mice are a significant cause of seabird mortality in this island ecosystem

Overscreening and Underscreening in Solid-Electrolyte Grain Boundary Space-Charge Layers

Polycrystalline solids can exhibit material properties that differ significantly from those of equivalent single-crystal samples, in part, because of a spontaneous redistribution of mobile point defects into so-called space-charge regions adjacent to grain boundaries. The general analytical form of these space-charge regions is known only in the dilute limit, where defect-defect correlations can be neglected. Using kinetic Monte Carlo simulations of a three-dimensional Coulomb lattice gas, we show that grain-boundary space-charge regions in non-dilute solid electrolytes exhibit overscreening -- damped oscillatory space-charge profiles -- and underscreening -- decay lengths that are longer than the corresponding Debye length and that increase with increasing defect-defect interaction strength. Overscreening and underscreening are known phenomena in concentrated liquid electrolytes, and the observation of functionally analogous behaviour in solid electrolyte space-charge regions suggests that the same underlying physics drives behaviour in both classes of systems. We therefore expect theoretical approaches developed to study non-dilute liquid electrolytes to be equally applicable to future studies of solid electrolytes

The Intestinal Microbiota Contributes to the Ability of Helminths to Modulate Allergic Inflammation

We thank Manuel Kulagin for technical help, Pierre Bonnaventure for portal vein blood sampling, Francisco Sepulveda for technical assistance in GS-MS acquisition, and Dorothee Hahne (Metabolomics Australia, University of Western Australia) for human samples SCFA isolation, acquisition, and analysis. We also thank Cristina Cartoni (Phenotyping Unit, EPFL) for Milliplex analysis, Jessica Dessimoz and her team from the Histology Core Facility (EPFL), Miguel Garcia and his team from the Flow Cytometry Core Facility (EPFL), and staff from the EPFL CPG animal house for excellent animal care. The computations were partially performed at the Vital-IT Center for high-performance computing of the SIB Swiss Institute of Bioinformatics (http://www.vital-it.ch). The research leading to these results has received funding from the European Research Council under the European Union’s Seventh Framework Programme (FP/2007-2013) / ERC Grant Agreement n. 310948. Funding for A.W.W. and a subset of the 16S rRNA gene sequencing was provided by the Wellcome Trust (grant number WT 098051). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Peer reviewedPublisher PD

Revisiting Soil C and N Sampling: Quantitative Pits vs. Rotary Cores

Increasing atmospheric carbon dioxide and its feedbacks with global climate have sparked renewed interest in quantifying ecosystem carbon (C) budgets, including quantifying belowground pools. Belowground nutrient budgets require accurate estimates of soil mass, coarse fragment content, and nutrient concentrations. It has long been thought that the most accurate measurement of soil mass and coarse fragment content has come from excavating quantitative soil pits. However, this methodology is labor intensive and time consuming. We propose that diamond-tipped rotary cores are an acceptable if not superior alternative to quantitative soil pits for the measurement of soil mass, coarse fragment content, C and total nitrogen (N) concentrations. We tested the rotary core methodology against traditional quantitative pits at research sites in California, Nevada, and New York. We found that soil cores had 16% higher estimates of less than 2-mm soil mass than estimates obtained from quantitative pits. Conversely, soil cores had 8% lower estimates of coarse fragment mass compared with quantitative pits. There were no statistical differences in measured C or N concentrations between the two methods. At the individual site level, differences in estimates for the two methods were more pronounced, but there was no consistent tendency for cores to overestimate or underestimate a soil parameter when compared with quantitative pits

Advances in non-invasive biosensing measures to monitor wound healing progression

Impaired wound healing is a significant financial and medical burden. The synthesis and deposition of extracellular matrix (ECM) in a new wound is a dynamic process that is constantly changing and adapting to the biochemical and biomechanical signaling from the extracellular microenvironments of the wound. This drives either a regenerative or fibrotic and scar-forming healing outcome. Disruptions in ECM deposition, structure, and composition lead to impaired healing in diseased states, such as in diabetes. Valid measures of the principal determinants of successful ECM deposition and wound healing include lack of bacterial contamination, good tissue perfusion, and reduced mechanical injury and strain. These measures are used by wound-care providers to intervene upon the healing wound to steer healing toward a more functional phenotype with improved structural integrity and healing outcomes and to prevent adverse wound developments. In this review, we discuss bioengineering advances in 1) non-invasive detection of biologic and physiologic factors of the healing wound, 2) visualizing and modeling the ECM, and 3) computational tools that efficiently evaluate the complex data acquired from the wounds based on basic science, preclinical, translational and clinical studies, that would allow us to prognosticate healing outcomes and intervene effectively. We focus on bioelectronics and biologic interfaces of the sensors and actuators for real time biosensing and actuation of the tissues. We also discuss high-resolution, advanced imaging techniques, which go beyond traditional confocal and fluorescence microscopy to visualize microscopic details of the composition of the wound matrix, linearity of collagen, and live tracking of components within the wound microenvironment. Computational modeling of the wound matrix, including partial differential equation datasets as well as machine learning models that can serve as powerful tools for physicians to guide their decision-making process are discussed

The Design of a Best Execution Market

The notion of best execution on securities markets is manifold. Best execution has different meanings to different market participants, therefore, it is difficult to find a unique market structure that meets this requirements for all the participants. Traditional market structures are either static or flexible, meaning that an individual market participant has no influence regarding the concrete market structure’s characteristics, like e. g. the price discovery mechanism, trading frequency or the market transparency. Traditional market structures are either static or flexible, meaning that an individual market participant has no influence regarding the Focussing on customer orientation, we propose a new type of market structure: the dynamic market model, where participants individually choose the characteristics of the market structure for each transaction they perform. Furthermore, this paper offers an approach to design dynamic market models from scratch. We briefly sketch the necessary steps towards a dynamic market model. Traditional market structures are either static or flexible, meaning that an individual market participant has no influence regarding the Finally, we present AMTRAS; the prototype of an electronic trading system that was conceived and implemented following the aforementioned approach. AMTRAS is an software-agent based bond trading system designed for the need of institutional investors. It implements a dynamic market model, a sophisticated product- and partner matching scheme as well as an innovative price discovery approach