A global model of the marine ecosystem for long-term simulations: Sensitivity to ocean mixing, buoyancy forcing, particle sinking, and dissolved organic matter cycling

A new model of the marine ecosystem coupled into a global Earth System Climate Model suitable for long-term (multimillennial timescale) simulations is presented. The model is based on nitrate as the sole limiting nutrient. Prognostic equations for nutrients, phytoplankton, zooplankton, and detritus are solved online in the three-dimensional ocean circulation model component. Experiments with different parameterizations of vertical mixing, including a scheme of tidally driven mixing, changes in buoyancy forcing in the Southern Ocean, different particle sinking velocities, and the inclusion of dissolved organic matter are performed, and the results are compared with observations. The results reemphasize the roles of Southern Ocean freshwater forcing and diapycnal mixing in the low-latitude pycnocline in setting the global deep water circulation and properties. The influence of high mixing in the Southern Ocean as inferred from observations is much more limited. The deep water circulation also has a strong influence on the marine ecosystem and nutrient distributions. We demonstrate that larger values of vertical diffusion lead to a shallower nutricline due to increased upwelling. Export production and nutrient distributions respond sensitively to changes in mixing and to the ratio of particle sinking to remineralization in the upper ocean. The best fits to global measurements of temperature, salinity, deep ocean radiocarbon, mixed layer depth, nutrients, and chlorophyll are obtained for values of vertical mixing in the pycnocline of around 0.2–0.3 X 10-4 m2/s and for e-folding depth for particle remineralization of 100–200 m. A simple parameterization of dissolved organic matter dynamics increases primary production and nutrient concentrations in the upper ocean and improves chlorophyll distributions in the subtropical gyres but has no discernible influence on particulate export fluxes. Remaining model deficiencies are identified, and strategies for future model improvement are outlined

Angiotensin II synergizes with BAFF to promote atheroprotective regulatory B cells.

Angiotensin II (AngII) promotes hypertension, atherogenesis, vascular aneurysm and impairs post-ischemic cardiac remodeling through concerted roles on vascular cells, monocytes and T lymphocytes. However, the role of AngII in B lymphocyte responses is largely unexplored. Here, we show that chronic B cell depletion (Baffr deficiency) significantly reduces atherosclerosis in Apoe -/- mice infused with AngII. While adoptive transfer of B cells in Apoe -/- /Baffr -/- mice reversed atheroprotection in the absence of AngII, infusion of AngII in B cell replenished Apoe -/- /Baffr -/- mice unexpectedly prevented the progression of atherosclerosis. Atheroprotection observed in these mice was associated with a significant increase in regulatory CD1dhiCD5+ B cells, which produced high levels of interleukin (IL)-10 (B10 cells). Replenishment of Apoe -/- /Baffr -/- mice with Il10 -/- B cells reversed AngII-induced B cell-dependent atheroprotection, thus highlighting a protective role of IL-10+ regulatory B cells in this setting. Transfer of AngII type 1A receptor deficient (Agtr1a -/-) B cells into Apoe -/- /Baffr -/- mice substantially reduced the production of IL-10 by B cells and prevented the AngII-dependent atheroprotective B cell phenotype. Consistent with the in vivo data, AngII synergized with BAFF to induce IL-10 production by B cells in vitro via AngII type 1A receptor. Our data demonstrate a previously unknown synergy between AngII and BAFF in inducing IL-10 production by B cells, resulting in atheroprotection

The Dendritic Cell Receptor DNGR-1 Promotes the Development of Atherosclerosis in Mice.

RATIONALE: Necrotic core formation during the development of atherosclerosis is associated with a chronic inflammatory response and promotes accelerated plaque development and instability. However, the molecular links between necrosis and the development of atherosclerosis are not completely understood. Clec9a (C-type lectin receptor) or DNGR-1 (dendritic cell NK lectin group receptor-1) is preferentially expressed by the CD8α+ subset of dendritic cells (CD8α+ DCs) and is involved in sensing necrotic cells. We hypothesized that sensing of necrotic cells by DNGR-1 plays a determinant role in the inflammatory response of atherosclerosis. OBJECTIVE: We sought to address the impact of total, bone marrow-restricted, or CD8α+ DC-restricted deletion of DNGR-1 on atherosclerosis development. METHODS AND RESULTS: We show that total absence of DNGR-1 in Apoe (apolipoprotein e)-deficient mice (Apoe-/-) and bone marrow-restricted deletion of DNGR-1 in Ldlr (low-density lipoprotein receptor)-deficient mice (Ldlr-/-) significantly reduce inflammatory cell content within arterial plaques and limit atherosclerosis development in a context of moderate hypercholesterolemia. This is associated with a significant increase of the expression of interleukin-10 (IL-10). The atheroprotective effect of DNGR-1 deletion is completely abrogated in the absence of bone marrow-derived IL-10. Furthermore, a specific deletion of DNGR-1 in CD8α+ DCs significantly increases IL-10 expression, reduces macrophage and T-cell contents within the lesions, and limits the development of atherosclerosis. CONCLUSIONS: Our results unravel a new role of DNGR-1 in regulating vascular inflammation and atherosclerosis and potentially identify a new target for disease modulation

Infrastructure for Detector Research and Development towards the International Linear Collider

The EUDET-project was launched to create an infrastructure for developing and testing new and advanced detector technologies to be used at a future linear collider. The aim was to make possible experimentation and analysis of data for institutes, which otherwise could not be realized due to lack of resources. The infrastructure comprised an analysis and software network, and instrumentation infrastructures for tracking detectors as well as for calorimetry.Comment: 54 pages, 48 picture

Simulating the global distribution of nitrogen isotopes in the ocean

We present a new nitrogen isotope model incorporated into the three-dimensional ocean component of a global Earth system climate model designed for millennial timescale simulations. The model includes prognostic tracers for the two stable nitrogen isotopes, 14N and 15N, in the nitrate (NO3−), phytoplankton, zooplankton, and detritus variables of the marine ecosystem model. The isotope effects of algal NO3− uptake, nitrogen fixation, water column denitrification, and zooplankton excretion are considered as well as the removal of NO3− by sedimentary denitrification. A global database of δ15NO3− observations is compiled from previous studies and compared to the model results on a regional basis where sufficient observations exist. The model is able to qualitatively and quantitatively reproduce many of the observed patterns such as high subsurface values in water column denitrification zones and the meridional and vertical gradients in the Southern Ocean. The observed pronounced subsurface minimum in the Atlantic is underestimated by the model presumably owing to too little simulated nitrogen fixation there. Sensitivity experiments reveal that algal NO3− uptake, nitrogen fixation, and water column denitrification have the strongest effects on the simulated distribution of nitrogen isotopes, whereas the effect from zooplankton excretion is weaker. Both water column and sedimentary denitrification also have important indirect effects on the nitrogen isotope distribution by reducing the fixed nitrogen inventory, which creates an ecological niche for nitrogen fixers and, thus, stimulates additional N2 fixation in the model. Important model deficiencies are identified, and strategies for future improvement and possibilities for model application are outlined

Individual Human Brain Areas Can Be Identified from Their Characteristic Spectral Activation Fingerprints

The human brain can be parcellated into diverse anatomical areas. We investigated whether rhythmic brain activity in these areas is characteristic and can be used for automatic classification. To this end, resting-state MEG data of 22 healthy adults was analysed. Power spectra of 1-s long data segments for atlas-defined brain areas were clustered into spectral profiles (“fingerprints”), using k-means and Gaussian mixture (GM) modelling. We demonstrate that individual areas can be identified from these spectral profiles with high accuracy. Our results suggest that each brain area engages in different spectral modes that are characteristic for individual areas. Clustering of brain areas according to similarity of spectral profiles reveals well-known brain networks. Furthermore, we demonstrate task-specific modulations of auditory spectral profiles during auditory processing. These findings have important implications for the classification of regional spectral activity and allow for novel approaches in neuroimaging and neurostimulation in health and disease

The Evolution of Invasiveness in Garden Ants

It is unclear why some species become successful invaders whilst others fail, and whether invasive success depends on pre-adaptations already present in the native range or on characters evolving de-novo after introduction. Ants are among the worst invasive pests, with Lasius neglectus and its rapid spread through Europe and Asia as the most recent example of a pest ant that may become a global problem. Here, we present the first integrated study on behavior, morphology, population genetics, chemical recognition and parasite load of L. neglectus and its non-invasive sister species L. turcicus. We find that L. neglectus expresses the same supercolonial syndrome as other invasive ants, a social system that is characterized by mating without dispersal and large networks of cooperating nests rather than smaller mutually hostile colonies. We conclude that the invasive success of L. neglectus relies on a combination of parasite-release following introduction and pre-adaptations in mating system, body-size, queen number and recognition efficiency that evolved long before introduction. Our results challenge the notion that supercolonial organization is an inevitable consequence of low genetic variation for chemical recognition cues in small invasive founder populations. We infer that low variation and limited volatility in cuticular hydrocarbon profiles already existed in the native range in combination with low dispersal and a highly viscous population structure. Human transport to relatively disturbed urban areas thus became the decisive factor to induce parasite release, a well established general promoter of invasiveness in non-social animals and plants, but understudied in invasive social insects

Reception Test of Petals for the End Cap TEC+ of the CMS Silicon Strip Tracker

The silicon strip tracker of the CMS experiment has been completed and was inserted into the CMS detector in late 2007. The largest sub system of the tracker are its end caps, comprising two large end caps (TEC) each containing 3200 silicon strip modules. To ease construction, the end caps feature a modular design: groups of about 20 silicon modules are placed on sub-assemblies called petals and these self-contained elements are then mounted onto the TEC support structures. Each end cap consists of 144 such petals, which were built and fully qualified by several institutes across Europe. Fro