1,767 research outputs found

    Learning for Sustainability: Partnership for the Goals

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    Rebuild by Design Phase 1 Evaluation Report

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    Rebuild by Design (RBD) was formally launched on June 20, 2013, to ensure that the rebuilding after Hurricane Sandy incorporated designs that built in resilience. RBD was launched with strong public leadership, philanthropic support and professional interest within the design community. The early enthusiasm for RBD came as much from curiosity about RBD's vision and ambition as from the substantial size of the implementation awards from the Community Development Block Grant Disaster Recovery (CDBG-DR) funds that Congress appropriated to the U.S. Department of Housing and Urban Development for Hurricane Sandy Recovery.As part of its ongoing commitment to learn from the work it supports, the Rockefeller Foundation provided funding for the Urban Institute to evaluate the design competition component of Phase 1 of RBD, including its innovative aspects, partnerships and community engagement

    Efficient training sets for surrogate models of tokamak turbulence with Active Deep Ensembles

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    Model-based plasma scenario development lies at the heart of the design and operation of future fusion powerplants. Including turbulent transport in integrated models is essential for delivering a successful roadmap towards operation of ITER and the design of DEMO-class devices. Given the highly iterative nature of integrated models, fast machine-learning-based surrogates of turbulent transport are fundamental to fulfil the pressing need for faster simulations opening up pulse design, optimization, and flight simulator applications. A significant bottleneck is the generation of suitably large training datasets covering a large volume in parameter space, which can be prohibitively expensive to obtain for higher fidelity codes. In this work, we propose ADEPT (Active Deep Ensembles for Plasma Turbulence), a physics-informed, two-stage Active Learning strategy to ease this challenge. Active Learning queries a given model by means of an acquisition function that identifies regions where additional data would improve the surrogate model. We provide a benchmark study using available data from the literature for the QuaLiKiz quasilinear transport model. We demonstrate quantitatively that the physics-informed nature of the proposed workflow reduces the need to perform simulations in stable regions of the parameter space, resulting in significantly improved data efficiency. We show an up to a factor of 20 reduction in training dataset size needed to achieve the same performance as random sampling. We then validate the surrogates on multichannel integrated modelling of ITG-dominated JET scenarios and demonstrate that they recover the performance of QuaLiKiz to better than 10\%. This matches the performance obtained in previous work, but with two orders of magnitude fewer training data points.Comment: Submitted to Nuclear Fusion. Comments welcom

    Para- and Ortho-Substitutions Are Key Determinants of Polybrominated Diphenyl Ether Activity toward Ryanodine Receptors and Neurotoxicity

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    BackgroundPolybrominated diphenyl ethers (PBDEs) are widely used flame retardants that bioaccumulate in human tissues. Their neurotoxicity involves dysregulation of calcium ion (Ca(2+))signaling; however, specific mechanisms have yet to be defined.ObjectiveWe aimed to define the structure-activity relationship (SAR) for PBDEs and their metabolites toward ryanodine receptors type 1 (RyR1) and type 2 (RyR2) and to determine whether it predicts neurotoxicity.MethodsWe analyzed [3H]ryanodine binding, microsomal Ca(2+) fluxes, cellular measurements of Ca(2+) homeostasis, and neurotoxicity to define mechanisms and specificity of PBDE-mediated Ca(2+) dysregulation.ResultsPBDEs possessing two ortho-bromine substituents and lacking at least one para-bromine substituent (e.g., BDE-49) activate RyR1 and RyR2 with greater efficacy than corresponding congeners with two para-bromine substitutions (e.g., BDE-47). Addition of a methoxy group in the free para position reduces the activity of parent PBDEs. The hydroxylated BDEs 6-OH-BDE-47 and 4´-OH-BDE-49 are biphasic RyR modulators. Pretreatment of HEK293 cells (derived from human embryonic kidney cells) expressing either RyR1 or RyR2 with BDE-49 (250 nM) sensitized Ca2+ flux triggered by RyR agonists, whereas BDE-47 (250 nM) had negligible activity. The divergent activity of BDE-49, BDE-47, and 6-OH-BDE-47 toward RyRs predicted neurotoxicity in cultures of cortical neurons.ConclusionsWe found that PBDEs are potent modulators of RyR1 and RyR2. A stringent SAR at the ortho and para position determined whether a congener enhanced, inhibited, or exerted nonmonotonic actions toward RyRs. These results identify a convergent molecular target of PBDEs previously identified for noncoplanar polychlorinated biphenyls (PCBs) that predicts their cellular neurotoxicity and therefore could be a useful tool in risk assessment of PBDEs and related compounds

    Adaptation of HIV-1 Envelope Glycoprotein gp120 to Humoral Immunity over the Course of the Epidemic

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    Since 2009, a large panel of broad and potent monoclonal neutralizing antibodies (MoNAbs) against HIV-1 have been isolated. These MoNAbs can protect from lllV-1 infection and suppress established infection in animal models. Because their efficacy should be evaluated in human clinical trials, it is of importance to define the sensitivity of the most contemporary transmitted variants to these MoNAbs. We, and others previously, reported that HIV-1 has become more resistant to neutralization over the course of the epidemic (Bunnik et al., Nature Med 2010, Bouvin-Pley et al., PloS Pathog 2013). Methods: Here we extended the analyses to the most potent MoNAbs described since then, either more recently isolated or improved by structure-based gene modifications. Results: We fully confirmed the first observations showing an increasing resistance of HIV-1 clade B over time to MoNAbs targeting the major gp l20 epitopes but not to MoNAbs targeting the gp41 MPER. Despite this evolution, some MoNAbs still were able to neutralize efficiently the most recently transmitted HIV-1 variants (2006-2010). The most potent MoNAbs were the bi-specific PG9- and PG16-iMab that alone were able to neutralize an variants at less than 0.4 mg/mL. The sensitivity to iMAb remained similar over time, suggesting that the trend of increasing resistance to PG9-/PG16-iMAb may be attributed only to die antigen binding domain of PG9/PG16. NIH45-46m2 (and -m7), 10-1074 and 10E8 were also highly potent and, if combined, reached the potency of PG9-/PG16-iMAb. We also observed that 3BNC 117 was almost as potent as the modified NIH45-46 antibodies, and that the lama-derived JM4IgG2b was the most potent Ab among those that do not target the major gp 120 neutralizing epitopes. Conclusions: These data clearly suggest a continuous drift of the env gene of HIV-1 elude B over the epidemic, and that not a single epitope is concerned but the entire gp120 as a whole. The consequences of this adaptation on the envelope functionality are being explored

    Surveillance of alloantibodies after transplantation identifies the risk of chronic rejection

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    The monitoring of the levels of alloantibodies following transplantation might facilitate early diagnosis of chronic rejection (CR), the leading cause of renal allograft failure. Here, we used serial alloantibody surveillance to monitor patients with preoperative positive flow cytometric crossmatch (FCXM). Sixty-nine of 308 renal transplant patients in our center had preoperative positive FCXM. Blood was collected quarterly during the first postoperative year and tested by FCXM and single antigen bead luminometry, more sensitive techniques than complement-dependent cytotoxic crossmatching. Distinct post-transplant profiles emerged and were associated with different clinical outcomes. Two-thirds of patients showed complete elimination of FCXM and solid-phase assay reactions within 1 year, had few adverse events, and a 95% 3-year graft survival. In contrast, the remaining third failed to eliminate flow FCXM or solid-phase reactions directed against HLA class I or II antibodies. The inferior graft survival (67%) with loss in this latter group was primarily due to CR. Thus, systematic assessment of longitudinal changes in alloantibody levels, either by FCXM or solid-phase assay, can help identify patients at greater risk of developing CR

    Effort required to finish shotgun-generated genome sequences differs significantly among vertebrates

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    <p>Abstract</p> <p>Background</p> <p>The approaches for shotgun-based sequencing of vertebrate genomes are now well-established, and have resulted in the generation of numerous draft whole-genome sequence assemblies. In contrast, the process of refining those assemblies to improve contiguity and increase accuracy (known as 'sequence finishing') remains tedious, labor-intensive, and expensive. As a result, the vast majority of vertebrate genome sequences generated to date remain at a draft stage.</p> <p>Results</p> <p>To date, our genome sequencing efforts have focused on comparative studies of targeted genomic regions, requiring sequence finishing of large blocks of orthologous sequence (average size 0.5-2 Mb) from various subsets of 75 vertebrates. This experience has provided a unique opportunity to compare the relative effort required to finish shotgun-generated genome sequence assemblies from different species, which we report here. Importantly, we found that the sequence assemblies generated for the same orthologous regions from various vertebrates show substantial variation with respect to misassemblies and, in particular, the frequency and characteristics of sequence gaps. As a consequence, the work required to finish different species' sequences varied greatly. Application of the same standardized methods for finishing provided a novel opportunity to "assay" characteristics of genome sequences among many vertebrate species. It is important to note that many of the problems we have encountered during sequence finishing reflect unique architectural features of a particular vertebrate's genome, which in some cases may have important functional and/or evolutionary implications. Finally, based on our analyses, we have been able to improve our procedures to overcome some of these problems and to increase the overall efficiency of the sequence-finishing process, although significant challenges still remain.</p> <p>Conclusion</p> <p>Our findings have important implications for the eventual finishing of the draft whole-genome sequences that have now been generated for a large number of vertebrates.</p

    Fluorosed Mouse Ameloblasts Have Increased SATB1 Retention and Gαq Activity

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    Dental fluorosis is characterized by subsurface hypomineralization and increased porosity of enamel, associated with a delay in the removal of enamel matrix proteins. To investigate the effects of fluoride on ameloblasts, A/J mice were given 50 ppm sodium fluoride in drinking water for four weeks, resulting serum fluoride levels of 4.5 µM, a four-fold increase over control mice with no fluoride added to drinking water. MicroCT analyses showed delayed and incomplete mineralization of fluorosed incisor enamel as compared to control enamel. A microarray analysis of secretory and maturation stage ameloblasts microdissected from control and fluorosed mouse incisors showed that genes clustered with Mmp20 appeared to be less downregulated in maturation stage ameloblasts of fluorosed incisors as compared to control maturation ameloblasts. One of these Mmp20 co-regulated genes was the global chromatin organizer, special AT-rich sequence-binding protein-1 (SATB1). Immunohistochemical analysis showed increased SATB1 protein present in fluorosed ameloblasts compared to controls. In vitro, exposure of human ameloblast-lineage cells to micromolar levels of both NaF and AlF3 led to a significantly increase in SATB1 protein content, but not levels of Satb1 mRNA, suggesting a fluoride-induced mechanism protecting SABT1 from degradation. Consistent with this possibility, we used immunohistochemistry and Western blot to show that fluoride exposed ameloblasts had increased phosphorylated PKCα both in vivo and in vitro. This kinase is known to phosphorylate SATB1, and phosphorylation is known to protect SATB1 from degradation by caspase-6. In addition, production of cellular diacylglycerol (DAG) was significantly increased in fluorosed ameloblasts, suggesting that the increased phosphorylation of SATB1 may be related to an effect of fluoride to enhance Gαq activity of secretory ameloblasts
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