192 research outputs found

    Lensing in the Darkness: A Bayesian Analysis of 22 Chandra Sources at z≳6z \gtrsim 6 Shows No Evidence of Lensing

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    More than 200200 quasars have been detected so far at z>6z > 6, with only one showing clear signs of strong gravitational lensing. Some studies call for a missing population of lensed high-zz quasars, but their existence is still in doubt. A large fraction of high-zz quasars being lensed would have a significant effect on the shape of the intrinsic quasar luminosity function (QLF). Here, we perform the first systematic search for lensed X-ray-detected quasars at z≳6z \gtrsim 6 employing a Bayesian analysis, with the code BAYMAX, to look for morphological evidence of multiple images that may escape a visual inspection. We analyzed a sample of 22 quasars at z>5.8z > 5.8 imaged by the Chandra X-ray observatory and found none with statistically significant multiple images. In the sub-sample of the 8 sources with photon counts >20>20 we exclude multiple images with separations r>1′′r>1'' and count ratios f>0.4f>0.4, or with separations as small as 0.′′70.''7 and f>0.7f>0.7 at 95%95\% confidence level. Comparing this non-detection with predictions from theoretical models suggesting a high and a low lensed fraction, we placed upper limits on the bright-end slope, β\beta, of the QLF. Using only the sub-sample with 8 sources, we obtain, in the high-lensing model, a limit β<3.38\beta < 3.38. Assuming no multiple source is present in the full sample of 22 sources, we obtain β<2.89\beta < 2.89 and β<3.53\beta < 3.53 in the high and low lensing models, respectively. These constraints strongly disfavor steep QLF shapes previously proposed in the literature.Comment: Accepted for publication in MNRAS. This is the final version of the manuscript. 10 pages, 5 figure

    Collective Plasmonic-Molecular Modes in the Strong Coupling Regime

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    We demonstrate strong coupling between molecular excited states and surface plasmon modes of a slit array in a thin metal film. The coupling manifests itself as an anti-crossing behavior of the two newly formed polaritons. As the coupling strength grows, a new mode emerges, which is attributed to long range molecular interactions mediated by the plasmonic field. The new, molecular-like mode repels the polariton states, and leads to an opening of energy gaps both below and above the asymptotic free molecule energy.Comment: 8 pages, 6 figures, submitted to PR

    Parallel engineering of environmental bacteria and performance over years under jungle-simulated conditions

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    Engineered bacteria could perform many functions in the environment, for example, to remediate pollutants, deliver nutrients to crops or act as in-field biosensors. Model organisms can be unreliable in the field, but selecting an isolate from the thousands that naturally live there and genetically manipulating them to carry the desired function is a slow and uninformed process. Here, we demonstrate the parallel engineering of isolates from environmental samples by using the broad-host-range XPORT conjugation system (Bacillus subtilis mini-ICEBs1) to transfer a genetic payload to many isolates in parallel. Bacillus and Lysinibacillus species were obtained from seven soil and water samples from different locations in Israel. XPORT successfully transferred a genetic function (reporter expression) into 25 of these isolates. They were then screened to identify the best-performing chassis based on the expression level, doubling time, functional stability in soil, and environmentally-relevant traits of its closest annotated reference species, such as the ability to sporulate and temperature tolerance. From this library, we selected Bacillus frigoritolerans A3E1, re-introduced it to soil, and measured function and genetic stability in a contained environment that replicates jungle conditions. After 21 months of storage, the engineered bacteria were viable, could perform their function, and did not accumulate disruptive mutations.</jats:p

    Rebuilding the Post-Pandemic Economy

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    After suffering the worst economic shock since the Great Depression, the American economy is recovering in fits and starts. While many businesses are reopening their doors and thriving, continued uncertainty about the course of the virus, the inflation outlook, labor shortages, and many other factors are hampering a full return to normal activity. The COVID-19 pandemic reinforced and exacerbated many of the biggest structural economic challenges in our society. It precipitated the largest economic relief and stimulus spending in US history and transformed the way that millions of Americans live and work, with automation, e-commerce, and telework all playing a bigger role.The policy volume Rebuilding the Post Pandemic Economy examines important questions about how the post-pandemic economy will take shape. What are some initial lessons we can take away from the novel government programs that were deployed to provide economic relief and stimulus? How can we implement new infrastructure investments to maximize efficiency and equity, and best respond to the climate crisis? After a year of widespread school closures, what have we learned about the role of K-12 education in perpetuating or reducing social and economic inequities? And how should American trade policies evolve to promote economic recovery and strengthen America's role in the global economy

    New Cancer Immunotherapy Agents in Development: a report from an associated program of the 31

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    This report is a summary of \u27New Cancer Immunotherapy Agents in Development\u27 program, which took place in association with the 31st Annual Meeting of the Society for Immunotherapy of Cancer (SITC), on November 9, 2016 in National Harbor, Maryland. Presenters gave brief overviews of emerging clinical and pre-clinical immune-based agents and combinations, before participating in an extended panel discussion with multidisciplinary leaders, including members of the FDA, leading academic institutions and industrial drug developers, to consider topics relevant to the future of cancer immunotherapy

    Beyond BRAFV600: Clinical Mutation Panel Testing by Next-Generation Sequencing in Advanced Melanoma

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    The management of melanoma has evolved owing to improved understanding of its molecular drivers. To augment the current understanding of the prevalence, patterns, and associations of mutations in this disease, the results of clinical testing of 699 advanced melanoma patients using a pan-cancer next-generation sequencing (NGS) panel of hotspot regions in 46 genes were reviewed. Mutations were identified in 43 of the 46 genes on the panel. The most common mutations were BRAFV600 (36%), NRAS (21%), TP53 (16%), BRAFNon-V600 (6%), and KIT (4%). Approximately one-third of melanomas had >1 mutation detected, and the number of mutations per tumor was associated with melanoma subtype. Concurrent TP53 mutations were the most frequent events in tumors with BRAFV600and NRAS mutations. Melanomas with BRAFNon-V600mutations frequently harbored concurrent NRAS mutations (18%), which were rare in tumors with BRAFV600 mutations (1.6%). The prevalence of BRAFV600 and KIT mutations were significantly associated with melanoma subtypes, and BRAFV600 and TP53 mutations were significantly associated with cutaneous primary tumor location. Multiple potential therapeutic targets were identified in metastatic unknown primary and cutaneous melanomas that lacked BRAFV600and NRAS mutations. These results enrich our understanding of the patterns and clinical associations of oncogenic mutations in melanoma

    A cluster randomised controlled trial and evaluation and cost-effectiveness analysis of the Roots of Empathy schools-based programme for improving social and emotional well-being outcomes among 8- to 9-year-olds in Northern Ireland

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    Background:There is growing consensus regarding the importance of attending to children’s social and emotional well-being. There is now a substantial evidence base demonstrating the links between a child’s early social and emotional development and a range of key longer-term education, social and health outcomes. Universal school-based interventions provide a significant opportunity for early intervention in this area and yet the existing evidence base, particularly in relation to their long-term effects, is limited.Objectives and main outcomes:To determine the effectiveness and cost-effectiveness of Roots of Empathy (ROE), a universal school-based programme that, through attempting to enhance children’s empathy, seeks to achieve the following two main outcomes: improvement in prosocial behaviour and reduction in difficult behaviour.Design:A cluster randomised controlled trial and an economic evaluation. A total of 74 primary schools were randomly assigned to deliver ROE or to join a waiting list control group. Seven schools withdrew post randomisation and a further two withdrew before the immediate post-test time point. Children (n = 1278) were measured pre test and immediately post test, and then for 3 years following the end of the programme. Data were also collected from teachers and parents.Setting and participants:The intervention schools delivered ROE to their Year 5 children (aged 8–9 years) as a whole class.Intervention:ROE is delivered on a whole-class basis for one academic year (October–June). It consists of 27 lessons based around the monthly visit from a baby and parent who are usually recruited from the local community. Children learn about the baby’s growth and development and are encouraged to generalise from this to develop empathy towards others.Results:Although it was developed in Canada, the programme was very well received by schools, parents and children, and it was delivered effectively with high fidelity. ROE was also found to be effective in achieving small improvements in children’s prosocial behaviour (Hedges’ g = 0.20; p = 0.045) and reductions in their difficult behaviour (Hedges’ g = –0.16; p = 0.060) immediately post test. Although the gains in prosocial behaviour were not sustained after the immediately post-test time point, there was some tentative evidence that the effects associated with reductions in difficult behaviour may have remained up to 36 months from the end of the programme. These positive effects of ROE on children’s behaviour were not found to be associated with improvements in empathy or other social and emotional skills (such as emotional recognition and emotional regulation), on which the trial found no evidence of ROE having an effect. The study also found that ROE was likely to be cost-effective in line with national guidelines.Conclusions:These findings are consistent with those of other evaluations of ROE and suggest that it is an effective and cost-effective programme that can be delivered appropriately and effectively in regions such as Northern Ireland. A number of issues for further consideration are raised regarding opportunities to enhance the role of parents; how a time-limited programme such as ROE can form part of a wider and progressive curriculum in schools to build on and sustain children’s social and emotional development; and the need to develop a better theory of change for how ROE works.Trial registration:Current Controlled Trials ISRCTN07540423.Funding:This project was funded by the National Institute for Health Research (NIHR) Public Health Research programme and will be published in full in Public Health Research; Vol. 6, No. 4. See the NIHR Journals Library website for further project information

    Remodeling of the Cortical Structural Connectome in Posttraumatic Stress Disorder:Results from the ENIGMA-PGC PTSD Consortium

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    BACKGROUND: Posttraumatic stress disorder (PTSD) is accompanied by disrupted cortical neuroanatomy. We investigated alteration in covariance of structural networks associated with PTSD in regions that demonstrate the case-control differences in cortical thickness (CT) and surface area (SA). METHODS: Neuroimaging and clinical data were aggregated from 29 research sites in >1,300 PTSD cases and >2,000 trauma-exposed controls (age 6.2-85.2 years) by the ENIGMA-PGC PTSD working group. Cortical regions in the network were rank-ordered by effect size of PTSD-related cortical differences in CT and SA. The top-n (n = 2 to 148) regions with the largest effect size for PTSD > non-PTSD formed hypertrophic networks, the largest effect size for PTSD < non-PTSD formed atrophic networks, and the smallest effect size of between-group differences formed stable networks. The mean structural covariance (SC) of a given n-region network was the average of all positive pairwise correlations and was compared to the mean SC of 5,000 randomly generated n-region networks. RESULTS: Patients with PTSD, relative to non-PTSD controls, exhibited lower mean SC in CT-based and SA-based atrophic networks. Comorbid depression, sex and age modulated covariance differences of PTSD-related structural networks. CONCLUSIONS: Covariance of structural networks based on CT and cortical SA are affected by PTSD and further modulated by comorbid depression, sex, and age. The structural covariance networks that are perturbed in PTSD comport with converging evidence from resting state functional connectivity networks and networks impacted by inflammatory processes, and stress hormones in PTSD

    A Comparison of Methods to Harmonize Cortical Thickness Measurements Across Scanners and Sites

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    Results of neuroimaging datasets aggregated from multiple sites may be biased by site-specific profiles in participants’ demographic and clinical characteristics, as well as MRI acquisition protocols and scanning platforms. We compared the impact of four different harmonization methods on results obtained from analyses of cortical thickness data: (1) linear mixed-effects model (LME) that models site-specific random intercepts (LME INT), (2) LME that models both site-specific random intercepts and age-related random slopes (LME INT+SLP), (3) ComBat, and (4) ComBat with a generalized additive model (ComBat-GAM). Our test case for comparing harmonization methods was cortical thickness data aggregated from 29 sites, which included 1,340 cases with posttraumatic stress disorder (PTSD) (6.2–81.8 years old) and 2,057 trauma-exposed controls without PTSD (6.3–85.2 years old). We found that, compared to the other data harmonization methods, data processed with ComBat-GAM was more sensitive to the detection of significant case-control differences (Χ 2(3) = 63.704, p < 0.001) as well as case-control differences in age-related cortical thinning (Χ 2(3) = 12.082, p = 0.007). Both ComBat and ComBat-GAM outperformed LME methods in detecting sex differences (Χ 2(3) = 9.114, p = 0.028) in regional cortical thickness. ComBat-GAM also led to stronger estimates of age-related declines in cortical thickness (corrected p-values < 0.001), stronger estimates of case-related cortical thickness reduction (corrected p-values < 0.001), weaker estimates of age-related declines in cortical thickness in cases than controls (corrected p-values < 0.001), stronger estimates of cortical thickness reduction in females than males (corrected p-values < 0.001), and stronger estimates of cortical thickness reduction in females relative to males in cases than controls (corrected p-values < 0.001). Our results support the use of ComBat-GAM to minimize confounds and increase statistical power when harmonizing data with non-linear effects, and the use of either ComBat or ComBat-GAM for harmonizing data with linear effects
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