10,882 research outputs found
Phagocytosis in the brain: homeostasis and disease
Microglia are resident macrophages of the central nervous system and significantly contribute to overall brain function by participating in phagocytosis during development, homeostasis, and diseased states. Phagocytosis is a highly complex process that is specialized for the uptake and removal of opsonized and non-opsonized targets, such as pathogens, apoptotic cells, and cellular debris. While the role of phagocytosis in mediating classical innate and adaptive immune responses has been known for decades, it is now appreciated that phagocytosis is also critical throughout early neural development, homeostasis, and initiating repair mechanisms. As such, modulating phagocytic processes has provided unexplored avenues with the intent of developing novel therapeutics that promote repair and regeneration in the CNS. Here, we review the functional consequences that phagocytosis plays in both the healthy and diseased CNS, and summarize how phagocytosis contributes to overall pathophysiological mechanisms involved in brain injury and repair
On modular decompositions of system signatures
Considering a semicoherent system made up of components having i.i.d.
continuous lifetimes, Samaniego defined its structural signature as the
-tuple whose -th coordinate is the probability that the -th component
failure causes the system to fail. This -tuple, which depends only on the
structure of the system and not on the distribution of the component lifetimes,
is a very useful tool in the theoretical analysis of coherent systems.
It was shown in two independent recent papers how the structural signature of
a system partitioned into two disjoint modules can be computed from the
signatures of these modules. In this work we consider the general case of a
system partitioned into an arbitrary number of disjoint modules organized in an
arbitrary way and we provide a general formula for the signature of the system
in terms of the signatures of the modules.
The concept of signature was recently extended to the general case of
semicoherent systems whose components may have dependent lifetimes. The same
definition for the -tuple gives rise to the probability signature, which may
depend on both the structure of the system and the probability distribution of
the component lifetimes. In this general setting, we show how under a natural
condition on the distribution of the lifetimes, the probability signature of
the system can be expressed in terms of the probability signatures of the
modules. We finally discuss a few situations where this condition holds in the
non-i.i.d. and nonexchangeable cases and provide some applications of the main
results
Recent Developments on the Transformation of CO2 Utilising Ligand Cooperation and Related Strategies
Oleophobic Coated Composite Materials Based on Multi-Layer Graphitic Scaffolding: Applications within Aircraft Propellant Tanks and Oil-Spill Clean-Up
Transformation of a Norbornadiene Unit to Ethylenylcyclopentene Requiring Cooperation Between Boron and Rhodium Centers
Evolutionary origins and development of saw-teeth on the sawfish and sawshark rostrum (Elasmobranchii; Chondrichthyes)
A well-known characteristic of chondrichthyans (e.g. sharks, rays) is their covering of external skin denticles (placoid scales), but less well understood is the wide morphological diversity that these skin denticles can show. Some of the more unusual of these are the tooth-like structures associated with the elongate cartilaginous rostrum ‘saw’ in three chondrichthyan groups: Pristiophoridae (sawsharks; Selachii), Pristidae (sawfish; Batoidea) and the fossil Sclerorhynchoidea (Batoidea). Comparative topographic and developmental studies of the ‘saw-teeth’ were undertaken in adults and embryos of these groups, by means of three-dimensional-rendered volumes from X-ray computed tomography. This provided data on development and relative arrangement in embryos, with regenerative replacement in adults. Saw-teeth are morphologically similar on the rostra of the Pristiophoridae and the Sclerorhynchoidea, with the same replacement modes, despite the lack of a close phylogenetic relationship. In both, tooth-like structures develop under the skin of the embryos, aligned with the rostrum surface, before rotating into lateral position and then attaching through a pedicel to the rostrum cartilage. As well, saw-teeth are replaced and added to as space becomes available. By contrast, saw-teeth in Pristidae insert into sockets in the rostrum cartilage, growing continuously and are not replaced. Despite superficial similarity to oral tooth developmental organization, saw-tooth spatial initiation arrangement is associated with rostrum growth. Replacement is space-dependent and more comparable to that of dermal skin denticles. We suggest these saw-teeth represent modified dermal denticles and lack the ‘many-for-one’ replacement characteristic of elasmobranch oral dentitions
Constitutive changes in pigment concentrations: implications for estimating isoprene emissions using the photochemical reflectance index
The photochemical reflectance index (PRI), through its relationship with light use efficiency (LUE) and xanthophyll cycle activity, has recently been shown to hold potential for tracking isoprene emissions from vegetation. However, both PRI and isoprene emissions can also be influenced by changes in carotenoid pigment concentrations. Xanthophyll cycle activity and changes in carotenoid concentrations operate over different timescales but the importance of constitutive changes in pigment concentrations for accurately estimating isoprene emissions using PRI is unknown. To clarify the physiological mechanisms behind the PRI–isoprene relationship, the light environment of potted Salix viminalis (dwarf willow) trees was modified to induce acclimation in photosynthetic rates, phytopigments, isoprene emissions and PRI. Acclimation resulted in differences in pigment concentrations, isoprene emissions and PRI. Constitutive changes in carotenoid concentration were significantly correlated with both isoprene emissions and PRI, suggesting that the relationship between PRI and isoprene emissions is significantly influenced by constitutive pigment changes. Consequently knowledge regarding how isoprene emissions are affected by both longer term changes in total carotenoid concentrations and shorter term dynamic adjustments of LUE is required to facilitate interpretation of PRI for monitoring isoprene emissions
Assessing and monitoring ecosystems – indicators, concepts and their linkage to biodiversity and ecosystem services. D4.1 Review paper on ecological indicators.
Stopping Hydrogen Migration in its Tracks: The First Successful Synthesis of Group Ten Scorpionate Complexes Based on Azaindole Scaffolds
The first successful
synthesis and characterization of group 10 complexes featuring flexible
scorpionate ligands based on 7-azaindole heterocycles are reported
herein. Addition of 2 equiv of either KÂ[HBÂ(azaindolyl)3] or LiÂ[HBÂ(Me)Â(azaindolyl)2] to [MÂ(μ-Cl)Â(η,1η2-COEOMe)]2 leads
to the formation of 2 equiv of the complexes [MÂ{κ3-N,N,H-HBÂ(azaindolyl)3}Â(η,1η2-COEOMe)] and [MÂ{κ3-N,N,H-HBÂ(Me)Â(azaindolyl)2}Â(η,1η2-COEOMe)] (where M = Pt, Pd; COEOMe = 8-methoxycyclooct-4-en-1-ide),
respectively. In these reactions, the borohydride group is directed
toward the metal center forming square based pyramidal complexes.
In contrast to analogous complexes featuring other flexible scorpionate
ligands, no hydrogen migration from boron is observed in the complexes
studied. The fortuitous line widths observed in some of the 11B NMR spectra allow for a closer inspection of the B–H···metal
unit in scorpionate complexes than has previously been possible
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