5,946 research outputs found

    Microvesicles as vehicles for tissue regeneration: Changing of the guards

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    Purpose of Review: Microvesicles (MVs) have been recognised as mediators of stem cell function, enabling and guiding their regenerative effects. Recent Findings: MVs constitute one unique size class of extracellular vesicles (EVs) directly shed from the cell plasma membrane. They facilitate cell-to-cell communication via intercellular transfer of proteins, mRNA and microRNA (miRNA). MVs derived from stem cells, or stem cell regulatory cell types, have proven roles in tissue regeneration and repair processes. Their role in the maintenance of healthy tissue function throughout the life course and thus in age related health span remains to be elucidated. Summary: Understanding the biogenesis and mechanisms of action of MVs may enable the development of cell-free therapeutics capable of assisting in tissue maintenance and repair for a variety of age-related degenerative diseases. This review critically evaluates recent work published in this area and highlights important new findings demonstrating the use of MVs in tissue regeneration

    Making an impact: The influence of policies to reduce emissions from aviation on the business travel patterns of individual corporations

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    The contribution of aviation to global carbon dioxide (CO2) emissions is projected to triple by 2050. As nations strive to meet CO2 reduction targets, policy interventions to manage the growth of emissions arising from air travel are likely. Here, we investigate the potential influence of aviation emissions reduction policies on the business travel patterns of individual corporations. Using travel data from six UK-based companies, we find that increased ticket prices can deliver substantial emissions cuts, particularly on premium class flights, and may provide strong financial incentives to seek modal and/or technological alternatives to flying. We also find that corporations from different business sectors vary in their responsiveness to arange of policy options. Finally, we examine questionnaire data to determine whether companies more broadly are going beyond compliance to mitigate their environmental impact by managing travel-related emissions voluntarily. Although many corporations are measuring and reporting emissions, only a limited number are willing to implement in-house reduction policies prior to regulation

    The size, concentration, and growth of biodiversity-conservation nonprofits

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    Nonprofit organizations play a critical role in efforts to conserve biodiversity. Their success in this regard will be determined in part by how effectively individual nonprofits and the sector as a whole are structured. One of the most fundamental questions about an organization’s structure is how large it should be, with the logical counterpart being how concentrated the whole sector should be. We review empirical patterns in the size, concentration, and growth of over 1700 biodiversity-conservation nonprofits registered for tax purposes in the United States within the context of relevant economic theory. Conservation-nonprofit sizes vary by six to seven orders of magnitude and are positively skewed. Larger nonprofits access more revenue streams and hold more of their assets in land and buildings than smaller or midsized nonprofits do. The size of conservation nonprofits varies with the ecological focus of the organization, but the growth rates of nonprofits do not

    Using video feedback to improve early father-infant interaction: a pilot study.

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    Preventive interventions with parents of infants have tended to focus on mothers. Recent research focused on fathers suggests that their involvement in interventions might enhance effectiveness. One effective approach with mothers is the brief, home-based Video-feedback Intervention to promote Positive Parenting (VIPP). This paper is a report of a pilot study of VIPP with fathers to assess its feasibility. Five fathers were recruited from an existing longitudinal study of parents. The primary outcome was acceptability, assessed using a semi-structured questionnaire after completion of the intervention. All fathers completed all sessions of the intervention. Fathers rated the intervention as having had a significant impact on their understanding of their child's thoughts and feelings, and as having improved their communication and relationship with their baby. Fathers' feedback was generally positive. The flexibility to conduct sessions at home (or at fathers' places of work) and the flexible timing of sessions were identified as fundamental to successful delivery. The results of this pilot study are encouraging, as VIPP with fathers was feasible. In light of the modest sample size, and the use of a non-clinical sample, the intervention must be evaluated with larger, clinical samples to evaluate its efficacy with fathers

    Ultrastructural Distribution of the 7 Nicotinic Acetylcholine Receptor Subunit in Rat Hippocampus

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    Acetylcholine (ACh) is an important neurotransmitter in the mammalian brain; it is implicated in arousal, learning, and other cognitive functions. Recent studies indicate that nicotinic receptors contribute to these cholinergic effects, in addition to the established role of muscarinic receptors. In the hippocampus, where cholinergic involvement in learning and memory is particularly well documented, 7 nicotinic acetylcholine receptor subunits (7 nAChRs) are highly expressed, but their precise ultrastructural localization has not been determined. Here, we describe the results of immunogold labeling of serial ultrathin sections through stratum radiatum of area CA1 in the rat. Using both anti-7 nAChR immunolabeling and -bungarotoxin binding, we find that 7 nAChRs are present at nearly all synapses in CA1 stratum radiatum, with immunolabeling present at both presynaptic and postsynaptic elements. Morphological considerations and double immunolabeling indicate that GABAergic as well as glutamatergic synapses bear 7 nAChRs, at densities approaching those observed for glutamate receptors in CA1 stratum radiatum. Postsynaptically, 7 nAChRs often are distributed at dendritic spines in a perisynaptic annulus. In the postsynaptic cytoplasm, immunolabeling is associated with spine apparatus and other membranous structures, suggesting that 7 nAChRs may undergo dynamic regulation, with insertion into the synapse and subsequent internalization. The widespread and substantial expression of 7 nAChRs at synapses in the hippocampus is consistent with an important role in mediating and/or modulating synaptic transmission, plasticity, and neurodegeneration

    The structure of classical extensions of quantum probability theory

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    On the basis of a suggestive definition of a classical extension of quantum mechanics in terms of statistical models, we prove that every such classical extension is essentially given by the so-called Misra–Bugajski reduction map. We consider how this map enables one to understand quantum mechanics as a reduced classical statistical theory on the projective Hilbert space as phase space and discuss features of the induced hidden-variable model. Moreover, some relevant technical results on the topology and Borel structure of the projective Hilbert space are reviewed

    Pupal surveys for Aedes aegypti surveillance and potential targeted control in residential areas of Mérida, México.

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    A mosquito larval-pupal survey was conducted in 1,160 households of the Mexican city of Mérida during the rainy season of 2003 to determine their differential productivity for Aedes aegypti. Larvae and pupae were detected in 15 broad categories of container types. All breeding sites were found in the patios (backyards) and were potentially rain filled. Ae. aegypti pupae were produced from all categories of breeding site, and no single container type was predominately responsible for pupal production. The most productive buckets comprised 42% of the pupae-positive containers and provided 34% of the total pupae collected. Pupal production in buckets, together with plastic rubbish, pet dishes and basins, utensils for cooking and washing, tires, and flowerpots, accounted for almost 87% of pupal production. However, the most important pupal producers had low infestation indices for immature forms, illustrating that the use of positive-container indices can underestimate the importance of certain breeding sites. Overall, 40% of containers that were observed harboring Ae. aegypti pupae were classified as disposable. The remaining containers were considered useful, although some were seldom used. The discussion focuses on the potential utility of the pupal survey for targeting control, and its resulting pupae-per-person entomological indicator, both for comparison with a theoretical threshold for dengue transmission and for targeting vector control in this Mexican city
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