459 research outputs found

    NF-κB Activity Initiates Human ESC-Derived Neural Progenitor Cell Differentiation by Inducing a Metabolic Maturation Program.

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    Human neural development begins at embryonic day 19 and marks the beginning of organogenesis. Neural stem cells in the neural tube undergo profound functional, morphological, and metabolic changes during neural specification, coordinated by a combination of exogenous and endogenous cues. The temporal cell signaling activities that mediate this process, during development and in the postnatal brain, are incompletely understood. We have applied gene expression studies and transcription factor-activated reporter lentiviruses during in vitro neural specification of human pluripotent stem cells. We show that nuclear factor κB orchestrates a multi-faceted metabolic program necessary for the maturation of neural progenitor cells during neurogenesis

    Dessins d'enfants in N=2 generalised quiver theories

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    We study Grothendieck’s dessins d’enfants in the context of the N=2 supersymmetric gauge theories in (3 + 1) dimensions with product SU (2) gauge groups which have recently been considered by Gaiotto et al.. We identify the precise context in which dessins arise in these theories: they are the so-called ribbon graphs of such theories at certain isolated points in the moduli space. With this point in mind, we highlight connections to other work on trivalent dessins, gauge theories, and the modular group

    A large West Antarctic Ice Sheet explains early Neogene sea-level amplitude

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    Early to Middle Miocene sea-level oscillations of approximately 40-60 m estimated from far-field records1-3 are interpreted to reflect the loss of virtually all East Antarctic ice during peak warmth2. This contrasts with ice-sheet model experiments suggesting most terrestrial ice in East Antarctica was retained even during the warmest intervals of the Middle Miocene4,5. Data and model outputs can be reconciled if a large West Antarctic Ice Sheet (WAIS) existed and expanded across most of the outer continental shelf during the Early Miocene, accounting for maximum ice-sheet volumes. Here we provide the earliest geological evidence proving large WAIS expansions occurred during the Early Miocene (~17.72-17.40 Ma). Geochemical and petrographic data show glacimarine sediments recovered at International Ocean Discovery Program (IODP) Site U1521 in the central Ross Sea derive from West Antarctica, requiring the presence of a WAIS covering most of the Ross Sea continental shelf. Seismic, lithological and palynological data reveal the intermittent proximity of grounded ice to Site U1521. The erosion rate calculated from this sediment package greatly exceeds the long-term mean, implying rapid erosion of West Antarctica. This interval therefore captures a key step in the genesis of a marine-based WAIS and a tipping point in Antarctic ice-sheet evolution

    Modelling the Influence of Foot-and-Mouth Disease Vaccine Antigen Stability and Dose on the Bovine Immune Response

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    Foot and mouth disease virus causes a livestock disease of significant global socio-economic importance. Advances in its control and eradication depend critically on improvements in vaccine efficacy, which can be best achieved by better understanding the complex within-host immunodynamic response to inoculation. We present a detailed and empirically parametrised dynamical mathematical model of the hypothesised immune response in cattle, and explore its behaviour with reference to a variety of experimental observations relating to foot and mouth immunology. The model system is able to qualitatively account for the observed responses during in-vivo experiments, and we use it to gain insight into the incompletely understood effect of single and repeat inoculations of differing dosage using vaccine formulations of different structural stability

    "They don't care what happens to us." The situation of double orphans heading households in Rakai District, Uganda

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    <p>Abstract</p> <p>Background</p> <p>This article is based on information collected about the situation of double orphans who are heading households in Rakai District, Uganda. The information will be used as justification and guidance for planning actions to improve the situation of these and similar children. This research is thus the first step in an Action Research approach leading to specific interventions. The aim of this article is to describe the situation of these orphaned children, with an emphasis on the psychosocial challenges they face.</p> <p>Methods</p> <p>The study involved interviews, focus group discussions, observations and narratives. Forty-three heads of sibling-headed households participated. Information derived from informal discussions with local leaders is also included. The responses were analyzed using a modified version of Giorgi's psychological phenomenological method as described by Malterud <abbrgrp><abbr bid="B1">1</abbr></abbrgrp>.</p> <p>Results</p> <p>Factors such as lack of material resources, including food and clothes, limited possibilities to attend school on a regular basis, vast responsibilities and reduced possibilities for social interaction all contribute to causing worries and challenges for the child heads of households. Most of the children claimed that they were stigmatized and, to a great extent, ignored and excluded from their community. The Local Council Secretary ("Chairman") seemed to be the person in the community most responsible and helpful, but some chairmen seemed not to care at all. The children requested counseling for themselves as well as for community members because they experienced lack of understanding from other children and from adult community members.</p> <p>Conclusion</p> <p>The children experienced their situation as a huge and complex problem for themselves as well as for people in their villages. However, the situation might improve if actions focused on practical and psychological issues as well as on sensitization about the children's situation could be initiated. In addition to the fact that these children need adult guidance to become citizens who act in accordance with the expectations in their communities, material aid is important in order to reduce the children's experiences of being "different" and constantly experiencing survival anxieties.</p> <p indent="1"><it>Before my parents died, I was schooling without facing any problems and my heart was at rest. When they died I went to live with Jjajja [grandmother]. She fell very sick and I came out of school for a full term to look after her. I was treating Jjajja but she was not getting better. She died...so...I got my schoolmates' books and copied notes that they had taken while I was away from school...I face the problem of not having good friends. Some see me as a disease...other people are not bad. Some call me names and say that I am stupid, that I probably inherited the stupidity from my mother or father...Ever since my parents died, I have not had peace. I spend most of the time thinking, crying and struggling within myself asking God why He really had to do such a thing and saying to myself that: "God, help me overcome these problems!"</it></p> <p indent="1"><it>Girl, 15</it>.</p

    Search for new phenomena in final states with an energetic jet and large missing transverse momentum in pp collisions at √ s = 8 TeV with the ATLAS detector

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    Results of a search for new phenomena in final states with an energetic jet and large missing transverse momentum are reported. The search uses 20.3 fb−1 of √ s = 8 TeV data collected in 2012 with the ATLAS detector at the LHC. Events are required to have at least one jet with pT > 120 GeV and no leptons. Nine signal regions are considered with increasing missing transverse momentum requirements between Emiss T > 150 GeV and Emiss T > 700 GeV. Good agreement is observed between the number of events in data and Standard Model expectations. The results are translated into exclusion limits on models with either large extra spatial dimensions, pair production of weakly interacting dark matter candidates, or production of very light gravitinos in a gauge-mediated supersymmetric model. In addition, limits on the production of an invisibly decaying Higgs-like boson leading to similar topologies in the final state are presente

    Excitability and Synaptic Alterations in the Cerebellum of APP/PS1 Mice

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    In Alzheimer's disease (AD), the severity of cognitive symptoms is better correlated with the levels of soluble amyloid-beta (Aβ) rather than with the deposition of fibrillar Aβ in amyloid plaques. In APP/PS1 mice, a murine model of AD, at 8 months of age the cerebellum is devoid of fibrillar Aβ, but dosage of soluble Aβ1–42, the form which is more prone to aggregation, showed higher levels in this structure than in the forebrain. Aim of this study was to investigate the alterations of intrinsic membrane properties and of synaptic inputs in Purkinje cells (PCs) of the cerebellum, where only soluble Aβ is present. PCs were recorded by whole-cell patch-clamp in cerebellar slices from wild-type and APP/PS1 mice. In APP/PS1 PCs, evoked action potential discharge showed enhanced frequency adaptation and larger afterhyperpolarizations, indicating a reduction of the intrinsic membrane excitability. In the miniature GABAergic postsynaptic currents, the largest events were absent in APP/PS1 mice and the interspike intervals distribution was shifted to the left, but the mean amplitude and frequency were normal. The ryanodine-sensitive multivescicular release was not altered and the postsynaptic responsiveness to a GABAA agonist was intact. Climbing fiber postsynaptic currents were normal but their short-term plasticity was reduced in a time window of 100–800 ms. Parallel fiber postsynaptic currents and their short-term plasticity were normal. These results indicate that, in the cerebellar cortex, chronically elevated levels of soluble Aβ1–42 are associated with alterations of the intrinsic excitability of PCs and with alterations of the release of GABA from interneurons and of glutamate from climbing fibers, while the release of glutamate from parallel fibers and all postsynaptic mechanisms are preserved. Thus, soluble Aβ1–42 causes, in PCs, multiple functional alterations, including an impairment of intrinsic membrane properties and synapse-specific deficits, with differential consequences even in different subtypes of glutamatergic synapses

    Effect of Population, Collection Year, After-Ripening and Incubation Condition on Seed Germination of \u3cem\u3eStipa bungeana\u3c/em\u3e

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    Knowledge of the germination behavior of different populations of a species can be useful in the selection of appropriate seed sources for restoration. The aim of this study was to test the effect of seed population, collection year, after-ripening and incubation conditions on seed dormancy and germination of Stipa bungeana, a perennial grass used for revegetation of degraded grasslands on the Loess Plateau, China. Fresh S. bungeana seeds were collected from eight locally-adapted populations in 2015 and 2016. Dormancy and germination characteristics of fresh and 6-month-old dry-stored seeds were determined by incubating them over a range of alternating temperature regimes in light. Effect of water stress on germination was tested for fresh and 6-month-old dry-stored seeds. Seed dormancy and germination of S. bungeana differed with population and collection year. Six months of dry storage broke seed dormancy, broadened the temperature range for germination and increased among-population differences in germination percentage. The rank order of germination was not consistent in all germination tests, and it varied among populations. Thus, studies on comparing seed dormancy and germination among populations must consider year of collection, seed dormancy states and germination test conditions when selecting seeds for grassland restoration and management

    Mid- and long-term clinical results of surgical therapy in unicameral bone cysts

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    <p>Abstract</p> <p>Background</p> <p>Unicameral (or simple) bone cysts (UBC) are benign tumours most often located in long bones of children and adolescents. Pathological fractures are common, and due to high recurrence rates, these lesions remain a challenge to treat. Numerous surgical procedures have been proposed, but there is no general consensus of the ideal treatment. The aim of this investigation therefore was to study the long-term outcome after surgical treatment in UBC.</p> <p>Methods</p> <p>A retrospective analysis of 46 patients surgically treated for UBC was performed for short and mid-term outcome. Clinical and radiological outcome parameters were studied according to a modified Neer classification system. Long-term clinical information was retrieved via a questionnaire at a minimum follow-up of 10 years after surgery.</p> <p>Results</p> <p>Forty-six patients (17 female, 29 male) with a mean age of 10.0 ± 4.8 years and with histopathologically confirmed diagnosis of UBC were included. Pathological fractures were observed in 21 cases (46%). All patients underwent surgery for UBC (35 patients underwent curettage and bone grafting as a primary therapy, 4 curettage alone, 3 received corticoid instillation and 4 decompression by cannulated screws). Overall recurrence rate after the first surgical treatment was 39% (18/46), second (17.4% of all patients) and third recurrence (4.3%) were frequently observed and were addressed by revision surgery. Recurrence was significantly higher in young and in male patients as well as in active cysts. After a mean of 52 months, 40 out of 46 cysts were considered healed. Prognosis was significantly better when recurrence was observed later than 30 months after therapy. After a mean follow-up of 15.5 ± 6.2 years, 40 patients acknowledged clinically excellent results, while five reported mild and casual pain. Only one patient reported a mild limitation of range of motion.</p> <p>Conclusions</p> <p>Our results suggest satisfactory overall long-term outcome for the surgical treatment of UBC, although short-and mid-term observation show a considerable rate of recurrence independent of the surgical technique.</p
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