Vectors with autonomy: what distinguishes animal-mediated nutrient transport from abiotic vectors?

Animal movements are important drivers of nutrient redistribution that can affect primary productivity and biodiversity across various spatial scales. Recent work indicates that incorporating these movements into ecosystem models can enhance our ability to predict the spatio-temporal distribution of nutrients. However, the role of animal behaviour in animal-mediated nutrient transport (i.e. active subsidies) remains under-explored. Here we review the current literature on active subsidies to show how the behaviour of active subsidy agents makes them both ecologically important and qualitatively distinct from abiotic processes (i.e. passive subsidies). We first propose that animal movement patterns can create similar ecological effects (i.e. press and pulse disturbances) in recipient ecosystems, which can be equal in magnitude to or greater than those of passive subsidies. We then highlight three key behavioural features distinguishing active subsidies. First, organisms can transport nutrients counter-directionally to abiotic forces and potential energy gradients (e.g. upstream). Second, unlike passive subsidies, organisms respond to the patterns of nutrients that they generate. Third, animal agents interact with each other. The latter two features can form positive- or negative-feedback loops, creating patterns in space or time that can reinforce nutrient hotspots in places of mass aggregations and/or create lasting impacts within ecosystems. Because human-driven changes can affect both the space-use of active subsidy species and their composition at both population (i.e. individual variation) and community levels (i.e. species interactions), predicting patterns in nutrient flows under future modified environmental conditions depends on understanding the behavioural mechanisms that underlie active subsidies and variation among agents' contributions. We conclude by advocating for the integration of animal behaviour, animal movement data, and individual variation into future conservation efforts in order to provide more accurate and realistic assessments of changing ecosystem function

Posterior Vitreous Detachment and the Posterior Hyaloid Membrane

PURPOSE: Despite posterior vitreous detachment being a common ocular event affecting most individuals in an aging population, there is little consensus regarding its precise anatomic definition. We investigated the morphologic appearance and molecular composition of the posterior hyaloid membrane to determine whether the structure clinically observed enveloping the posterior vitreous surface after posterior vitreous detachment is a true basement membrane and to postulate its origin. Understanding the relationship between the vitreous (in both its attached and detached state) and the internal limiting membrane of the retina is essential to understanding the cause of rhegmatogenous retinal detachment and vitreoretinal interface disorders, as well as potential future prophylactic and treatment strategies. DESIGN: Clinicohistologic correlation study. PARTICIPANTS: Thirty-six human donor globes. METHODS: Vitreous bodies identified to have posterior vitreous detachment were examined with phase-contrast microscopy and confocal microscopy after immunohistochemically staining for collagen IV basement membrane markers, in addition to extracellular proteins that characterize the vitreoretinal junction (fibronectin, laminin) and vitreous gel (opticin) markers. The posterior retina similarly was stained to evaluate the internal limiting membrane. Findings were correlated to the clinical appearance of the posterior hyaloid membrane observed during slit-lamp biomicroscopy after posterior vitreous detachment and compared with previously published studies. MAIN OUTCOME MEASURES: Morphologic appearance and molecular composition of the posterior hyaloid membrane. RESULTS: Phase-contrast microscopy consistently identified a creased and distinct glassy membranous sheet enveloping the posterior vitreous surface, correlating closely with the posterior hyaloid membrane observed during slit-lamp biomicroscopy in patients with posterior vitreous detachment. Immunofluorescent confocal micrographs demonstrated the enveloping membranous structure identified on phase-contrast microscopy to show positive stain results for type IV collagen. Immunofluorescence of the residual intact internal limiting membrane on the retinal surface also showed positive stain results for type IV collagen. CONCLUSIONS: The results of this study provide immunohistochemical evidence that the posterior hyaloid membrane is a true basement membrane enveloping the posterior hyaloid surface. Because this membranous structure is observed only after posterior vitreous detachment, the results of this study indicate that it forms part of the internal limiting membrane when the vitreous is in its attached state

Alternative splicing modifies the effect of mutations in COL11A1 and results in recessive type 2 Stickler syndrome with profound hearing loss.

BACKGROUND: Stickler syndromes types 1, 2 and 3 are usually dominant disorders caused by mutations in the genes COL2A1, COL11A1 and COL11A2 that encode the fibrillar collagens types II and XI present in cartilage and vitreous. Rare recessive forms of Stickler syndrome exist that are due to mutations in genes encoding type IX collagen (COL9A1 type 4 Stickler syndrome and COL9A2 type 5 Stickler syndrome). Recently, recessive mutations in the COL11A1 gene have been demonstrated to result in fibrochondrogenesis, a much more severe skeletal dysplasia, which is often lethal. Here we demonstrate that some mutations in COL11A1 are recessive, modified by alternative splicing and result in type 2 Stickler syndrome rather than fibrochondrogenesis. METHODS: Patients referred to the national Stickler syndrome diagnostic service for England, UK were assessed clinically and subsequently sequenced for mutations in COL11A1. Additional in silico and functional studies to assess the effect of sequence variants on pre-mRNA processing and collagen structure were performed. RESULTS: In three different families, heterozygous COL11A1 biallelic null, null/missense or silent/missense mutations, were found. They resulted in a recessive form of type 2 Stickler syndrome characterised by particularly profound hearing loss and are clinically distinct from the recessive types 4 and 5 variants of Stickler syndrome. One mutant allele in each family is capable of synthesising a normal α1(XI) procollagen molecule, via variable pre-mRNA processing. CONCLUSION: This new variant has important implications for molecular diagnosis and counselling families with type 2 Stickler syndrome

Elemental: A new framework for distributed memory dense matrix computations

Abstract Parallelizing dense matrix computations to distributed memory architectures is a well-studied subject and generally considered to be among the best understood domains of parallel computing. Two packages, developed in the mid 1990s, still enjoy regular use: ScaLAPACK and PLAPACK. With the advent of many-core architectures, which may very well take the shape of distributed memory architectures within a single processor, these packages must be revisited since it will likely not be practical to use MPI-based implementations. Thus, this is a good time to review lessons learned since the introduction of these two packages and to propose a simple yet effective alternative. Preliminary performance results show the new solution achieves competitive, if not superior, performance on large clusters (i.e., on two racks o

The (In)Stability Of The Relationship Between Stocks, Bonds And Managed Futures

This study re-examines the traditional belief that futures contracts have very low and, in some cases, negative correlations with stocks and bonds.  Specifically, it looks at the stability of the correlations between five indices of futures market performance and two stock and bond indices over various holding periods.  Results show that large positive correlations occur over short holding periods, but over the long run, the relationship is fairly stable, in particular for certain indices

Just you and I:The role of social exclusion in the formation of interpersonal relationships

Social exclusion, or ostracism, has been investigated primarily for its (typically negative) consequences for those subjected to it. Although the negative effects of exclusion on its recipients are undisputed, we suggest that it may have unrecognized benefits for those who perpetuate it. The present research investigated the possibility that social exclusion acts as a signal to others - either within or outside of an exclusive interaction - that a selected relationship is particularly cohesive. Participants interacted in triads in which one individual was or was not singled out for exclusion. Perpetrators of exclusion were perceived (by themselves and by the excluded person) as closer and more similar to each other, and were more likely to be subject to source memory confusions. These findings suggest that social exclusion has not only harmful consequences for its targets, but may have relational benefits for those who enact it. (C) 2016 Elsevier Inc. All rights reserved