Projected WIMP sensitivity of the LUX-ZEPLIN dark matter experiment

LUX-ZEPLIN (LZ) is a next-generation dark matter direct detection experiment that will operate 4850 feet underground at the Sanford Underground Research Facility (SURF) in Lead, South Dakota, USA. Using a two-phase xenon detector with an active mass of 7 tonnes, LZ will search primarily for low-energy interactions with weakly interacting massive particles (WIMPs), which are hypothesized to make up the dark matter in our galactic halo. In this paper, the projected WIMP sensitivity of LZ is presented based on the latest background estimates and simulations of the detector. For a 1000 live day run using a 5.6-tonne fiducial mass, LZ is projected to exclude at 90% confidence level spin-independent WIMP-nucleon cross sections above 1.4 × 10-48cm2 for a 40 GeV/c2 mass WIMP. Additionally, a 5σ discovery potential is projected, reaching cross sections below the exclusion limits of recent experiments. For spin-dependent WIMP-neutron(-proton) scattering, a sensitivity of 2.3 × 10−43 cm2 (7.1 × 10−42 cm2) for a 40 GeV/c2 mass WIMP is expected. With underground installation well underway, LZ is on track for commissioning at SURF in 2020

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

Influence of lipid and uric acid on delta C-13 and delta N-15 values of avian blood: Implications for trophic studies

No abstract availabl

Factors that influence assimilation rates and fractionation of nitrogen and carbon stable isotopes in avian blood and feathers

By switching great skuas Catharacta skua from one isotopically distinct diet to another, we measured diet-tissue discrimination factors and tested the assumption that dietary nitrogen and carbon isotope signatures are incorporated into blood and feathers at similar rates. We also examined the effects of metabolic rate and looked for evidence of isotopic routing. We found that blood delta(15)N and delta(13)C signatures altered after the diet switch at similar rates (14.4 d and 15.7 d, respectively). Qualitative analyses imply that the same was true with feathers. Mass balance calculations suggest that only a small amount of lipid is likely to be involved in the synthesis of blood and feathers. Differences in diet-tissue discrimination factors before and after the diet switch may mean that toward the end of the experiment, some of the nutrients for blood synthesis had been coming from stores. Repeated measures mixed models provided evidence that increases in metabolic rate might accelerate fractional turnover rates in blood. There is a need for more laboratory-based experimental isotope studies in order to address further questions that this study has raised

Bioamplification of mercury in great skua Catharacta skua chicks: The influence of trophic status as determined by stable isotope signatures of blood and feathers

Biomagnification of mercury was investigated via combined mercury and stable isotope analysis of the blood and feathers of great skua chicks from two colonies in the north-east Atlantic. There were significant positive correlations between delta(15)N signatures and mercury concentrations in the blood from chicks at both colonies suggesting that dietary specialization influences intraspecific variability in mercury burdens. The relationships were slightly weaker in feathers and therefore blood is probably a better monitoring unit. Adult blood was also assessed and in terms of biomonitoring may provide an index of mercury intake over the whole breeding season

Fatty acid signatures and stable isotopes as dietary indicators in North Sea seabirds

Fatty acid signatures (FAS) of plasma and stable isotopes of carbon (8 13 C) and nitrogen (delta N-15) of red blood cells were determined in northern gannets Morus bassanus, great skuas Sterco-rarius skua, shags Phalacrocorax aristotelis, and common guillemots Uria aalge from colonies in the North Sea (collected 2002 to 2003) in order to compare foraging ecologies, and especially to assess the extent to which birds feed on demersal or pelagic prey. The biochemical markers in great skua and gannet indicated that these species feed at a relatively high trophic level, and high variance, especially in great skua, demonstrated either a wide range of food types, individual dietary specialisation or both. The biochemical markers suggested that demersal fish are important constituents of great skua and gannet diets, and thus changes in fisheries discard rates probably influence these populations. In contrast, clear pelagic characteristics and low variance in the markers showed that the diet of common guillemots and shags is pelagic and varies little in composition. Comparison with the reference FAS data for North Sea fish confirmed the dependence of common guillemots on few shoaling pelagic species of fish, probably mainly young sandeels Ammodytes marinu

Assortative mating as a mechanism for rapid evolution of a migratory divide

There have been numerous recent observations of changes in the behavior and dynamics of migratory bird populations, but the plasticity of the migratory trait and our inability to track small animals over large distances have hindered investigation of the mechanisms behind migratory change. We used habitat-specific stable isotope signatures to show that recently evolved allopatric wintering populations of European blackcaps Sylvia atricapilla pair assortatively on their sympatric breeding grounds. Birds wintering further north also produce larger clutches and fledge more young. These findings describe an important process in the evolution of migratory divides, new migration routes, and wintering quarters. Temporal segregation of breeding is a way in which subpopulations of vertebrates may become isolated in sympatry

Annual variation in Great Skua diets: The importance of commercial fisheries and predation on seabirds revealed by combining dietary analyses

This study combines conventional dietary assessment with stable isotope techniques to describe Great Skua (Stercorarius skua) diet. Stable carbon and nitrogen isotope ratios in feathers of Great Skua chicks collected over three years were analyzed in conjunction with pellet and regurgitate collection. A significant drop in trophic status was detected in 1997, which likely resulted from an increase in herring and mackerel in the diet. These items were almost certainly obtained from a commercial trawler, as evidenced by a significant drop in territorial attendance during the ship's absence. Feathers yielded significantly different delta C-13 values among years, and part of this may have been related to a period of enhanced phytoplankton growth during 1996. A combined approach, such as the one described here, is likely to become increasingly useful in elucidating the diets of polyphagous birds

Techniques to link individual migration patterns of seabirds with diet specialization, condition and breeding performance

Relationships between seabird breeding and food supply have been subject to much study, but we know little about the influence of food suply in winter on survival and subsequent breeding performance of seabirds, or about the extent to which migrations and winter home ranges of seabirds are influenced by food abundance. The Great Skua Stercorarius skua is a colonially breeding seabird that displays a wide range of feeding techniques during and outside the breeding season. We deployed satellite PTTs and data loggers to determine migration routes and winter quarters of breeding adult Great Skuas. We also studied dietary preferences by direct observations and by use of fatty acid and stable isotope signatures, and measured body condition and breeding performance of individually colour marked birds. Our objective was to develop methods to investigate whether winter foraging conditions may influence subsequent breeding performance, and to collect data to assess whether migrations and winter ranges differed between individuals in ways that may relate to fitness. We found large differences in the winter home ranges of individual Great Skuas, with some wintering off Iberia and others off west Africa. The latter behaviour was unexpected and may represent a new habit to exploit waste from fisheries that have recently developed on the west African continental shelf. Fatty acid signatures provide a clear signal of the presence of demersal fish from fishcry discards in skua diet and can be used to assess the feeding preference of individuals. Stable isotopes of C and N in primary feathers show changes in diet of individuals through the period of moult, which is thought to be from September to December. These approaches show that combining the use of data loggers and sampling of forensic markers of colour ringed adults permits the winter diet of individuals to be related to their geographic location in winter and to their subsequent breeding performanc