505 research outputs found

    Proposal for Quantum Simulation via All-Optically Generated Tensor Network States

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    We devise an all-optical scheme for the generation of entangled multimode photonic states encoded in temporal modes of light. The scheme employs a nonlinear down-conversion process in an optical loop to generate one- and higher-dimensional tensor network states of light. We illustrate the principle with the generation of two different classes of entangled tensor network states and report on a variational algorithm to simulate the ground-state physics of many-body systems. We demonstrate that state-of-the-art optical devices are capable of determining the ground-state properties of the spin-1/2 Heisenberg model. Finally, implementations of the scheme are demonstrated to be robust against realistic losses and mode mismatch.Comment: 6 pages main text plus 6 pages Supplementary Material and many figures. Updated to published version. Comments welcom

    Is association of preterm birth with cognitive-neurophysiological impairments and ADHD symptoms consistent with a causal inference or due to familial confounds?

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    BACKGROUND: Preterm birth is associated with an increased risk for cognitive-neurophysiological impairments and attention-deficit/hyperactivity disorder (ADHD). Whether the associations are due to the preterm birth insult per se, or due to other risk factors that characterise families with preterm-born children, is largely unknown. METHODS: We employed a within-sibling comparison design, using cognitive-performance and event-related potential (ERP) measures from 104 preterm-born adolescents and 104 of their term-born siblings. Analyses focused on ADHD symptoms and cognitive and ERP measures from a cued continuous performance test, an arrow flanker task and a reaction time task. RESULTS: Within-sibling analyses showed that preterm birth was significantly associated with increased ADHD symptoms (β = 0.32, p = 0.01, 95% CI 0.05 to 0.58) and specific cognitive-ERP impairments, such as IQ (β = -0.20, p = 0.02, 95% CI -0.40 to -0.01), preparation-vigilance measures and measures of error processing (ranging from β = 0.71, -0.35). There was a negligible within-sibling association between preterm birth with executive control measures of inhibition (NoGo-P3, β = -0.07, p = 0.45, 95% CI -0.33 to 0.15) or verbal working memory (digit span backward, β = -0.05, p = 0.63, 95% CI -0.30 to 0.18). CONCLUSIONS: Our results suggest that the relationship between preterm birth with ADHD symptoms and specific cognitive-neurophysiological impairments (IQ, preparation-vigilance and error processing) is independent of family-level risk and consistent with a causal inference. In contrast, our results suggest that previously observed associations between preterm birth with executive control processes of inhibition and working memory are instead linked to background characteristics of families with a preterm-born child rather than preterm birth insult per se. These findings suggest that interventions need to target both preterm-birth specific and family-level risk factors

    Patterns of connectome variability in autism across five functional activation tasks: findings from the LEAP project

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    Background: Autism spectrum disorder (autism) is a complex neurodevelopmental condition with pronounced behavioral, cognitive, and neural heterogeneities across individuals. Here, our goal was to characterize heterogeneity in autism by identifying patterns of neural diversity as reflected in BOLD fMRI in the way individuals with autism engage with a varied array of cognitive tasks. Methods: All analyses were based on the EU-AIMS/AIMS-2-TRIALS multisite Longitudinal European Autism Project (LEAP) with participants with autism (n = 282) and typically developing (TD) controls (n = 221) between 6 and 30 years of age. We employed a novel task potency approach which combines the unique aspects of both resting state fMRI and task-fMRI to quantify task-induced variations in the functional connectome. Normative modelling was used to map atypicality of features on an individual basis with respect to their distribution in neurotypical control participants. We applied robust out-of-sample canonical correlation analysis (CCA) to relate connectome data to behavioral data. Results: Deviation from the normative ranges of global functional connectivity was greater for individuals with autism compared to TD in each fMRI task paradigm (all tasks p < 0.001). The similarity across individuals of the deviation pattern was significantly increased in autistic relative to TD individuals (p < 0.002). The CCA identified significant and robust brain-behavior covariation between functional connectivity atypicality and autism-related behavioral features. Conclusions: Individuals with autism engage with tasks in a globally atypical way, but the particular spatial pattern of this atypicality is nevertheless similar across tasks. Atypicalities in the tasks originate mostly from prefrontal cortex and default mode network regions, but also speech and auditory networks. We show how sophisticated modeling methods such as task potency and normative modeling can be used toward unravelling complex heterogeneous conditions like autism

    First Report of Root and Collar Rot Caused by Fusarium tricinctum and Fusarium avenaceum on Carrot in France

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    In 2017, carrot (Daucus carota L.) seed production represented around 22% of the area devoted to the production of vegetable fine seeds. Since 2015, symptoms of root and collar rot have been observed in carrot seed parcels located in the Central Region, one of the most important production zone in France. Diseased plants became dried prematurely, compromising seed development. Depending on the year and the climatic conditions, the disease in a same field can be considered as epidemic (rate losses between 30 to 100% of plants in 2016) or can impact plants more sporadically (less than 10% in 2017 and 2018). Sixteen diseased carrot samples (Nantaise type) were collected from five fields of seed production in the Central Region: two fields in 2016 and 2017, one field in 2018. Seven fungal isolates, obtained from lesions, were grown on Potato Dextrose Agar (PDA) medium and incubated for one week at 20°C in darkness. From the colony top, fluffy mycelium pigmented in pink, red, purple or orange was observed, with a red color at the reverse. To induce sporulation, isolates were grown on Synthetischer Nährstoffarmer Agar (SNA) medium during three weeks at 24°C in near-UV radiations under a 12h-photoperiod. Four isolates (FT001, FT003, FT007, FT017) developed orange sporodochia with lunar or crescent-shaped macroconidia (40.3 ± 0.8 × 5.9 ± 0.1 µm; n=90) and lime or pear-shaped microconidia (10.7 ± 0.2 × 7.7 ± 0.2 µm; n=60), as described in Fusarium tricinctum (Leslie and Summerell 2006). Three isolates (FA001, FA002, FA006) developed orange sporodochia with sickle-shaped macroconidia (50.5 ± 1.1 × 5.0 ± 0.1 µm; n= 60), but no microconidia, as observed in Fusarium avenaceum (Leslie and Summerell 2006). To confirm the identification, DNA was extracted from the mycelium of the seven isolates and molecular markers (ATP citrate lyase, ACL1; RNA polymerase II, RPB2) were used for PCR amplification (Gräfenhan et al. 2011; O’Donnell et al. 2013). The ACL1 sequences from the seven field isolates (GenBank Accession numbers MK183788-MK183791; MK181528-MK181530) were 99-100% identical with the ACL1 sequence of a reference F. tricinctum isolate (query coverages 99-100%; E-values of 0.0) and a reference F. avenaceum isolate (query coverages 98-99%; E-values of 0.0) [respectively DAOM 235630 isolate, GenBank Acc. No. JX397813 and BBA64135 isolate, GenBank Acc. No. JX397768, Niessen et al. 2012]. Using RPB2, sequences from field isolates (GenBank Acc. No. MK183109-MK183115) were 98.5-99.9% identical with the RPB2 sequence of a reference F. tricinctum isolate (query coverages 96-100%; E-values of 0.0) and a reference F. avenaceum isolate (query coverages 95-100%; E-values of 0.0) [respectively MRC 1895 isolate, GenBank Acc. No. MH582113 and MRC 1413 isolate, GenBank Acc. No. MH582082, O’Donnell et al. 2018]. To confirm pathogenicity, FT001 and FA002 were inoculated on collars of 10-weeks old carrot plants in the greenhouse. Forty plants per isolate and 40 control plants were used. Ten microliters of a conidial suspension (105 conidia.mL-1) - or sterile water for the controls - were deposited at the collar, previously wounded using a scalpel blade. Necrotic lesions developed at 20 dpi (FT001) and at 30 dpi (FA002). Fusarium tricinctum and F. avenaceum were re-isolated from the lesions and identified by sequencing using ACL1 and RPB2 markers. No isolation of Fusarium was obtained from the controls. To our knowledge, this is the first report of F. tricinctum and F. avenaceum in carrot in France

    VEZF1 elements mediate protection from DNA methylation

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    There is growing consensus that genome organization and long-range gene regulation involves partitioning of the genome into domains of distinct epigenetic chromatin states. Chromatin insulator or barrier elements are key components of these processes as they can establish boundaries between chromatin states. The ability of elements such as the paradigm &#946;-globin HS4 insulator to block the range of enhancers or the spread of repressive histone modifications is well established. Here we have addressed the hypothesis that a barrier element in vertebrates should be capable of defending a gene from silencing by DNA methylation. Using an established stable reporter gene system, we find that HS4 acts specifically to protect a gene promoter from de novo DNA methylation. Notably, protection from methylation can occur in the absence of histone acetylation or transcription. There is a division of labor at HS4; the sequences that mediate protection from methylation are separable from those that mediate CTCF-dependent enhancer blocking and USF-dependent histone modification recruitment. The zinc finger protein VEZF1 was purified as the factor that specifically interacts with the methylation protection elements. VEZF1 is a candidate CpG island protection factor as the G-rich sequences bound by VEZF1 are frequently found at CpG island promoters. Indeed, we show that VEZF1 elements are sufficient to mediate demethylation and protection of the APRT CpG island promoter from DNA methylation. We propose that many barrier elements in vertebrates will prevent DNA methylation in addition to blocking the propagation of repressive histone modifications, as either process is sufficient to direct the establishment of an epigenetically stable silent chromatin stat

    Visual word form processing deficits driven by severity of reading impairments in children with developmental dyslexia

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    The visual word form area (VWFA) in the left ventral occipito-temporal (vOT) cortex is key to fluent reading in children and adults. Diminished VWFA activation during print processing tasks is a common finding in subjects with severe reading problems. Here, we report fMRI data from a multicentre study with 140 children in primary school (7.9-12.2 years;55 children with dyslexia, 73 typical readers, 12 intermediate readers). All performed a semantic task on visually presented words and a matched control task on symbol strings. With this large group of children, including the entire spectrum from severely impaired to highly fluent readers, we aimed to clarify the association of reading fluency and left vOT activation during visual word processing. The results of this study confirm reduced word-sensitive activation within the left vOT in children with dyslexia. Interestingly, the association of reading skills and left vOT activation was especially strong and spatially extended in children with dyslexia. Thus, deficits in basic visual word form processing increase with the severity of reading disability but seem only weakly associated with fluency within the typical reading range suggesting a linear dependence of reading scores with VFWA activation only in the poorest readers

    Impact of the COVID-19 pandemic on children with and without affective dysregulation and their families

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    Analyzing COVID-19-related stress in children with affective dysregulation (AD) seems especially interesting, as these children typically show heightened reactivity to potential stressors and an increased use of maladaptive emotion regulation strategies. Children in out-of-home care often show similar characteristics to those with AD. Since COVID-19 has led to interruptions in psychotherapy for children with mental health problems and to potentially reduced resources to implement treatment strategies in daily life in families or in out-of-home care, these children might show a particularly strong increase in stress levels. In this study, 512 families of children without AD and 269 families of children with AD reported on COVID-19-related stress. The sample comprised screened community, clinical, and out-of-home care samples. Sociodemographic factors, characteristics of child and caregiver before the pandemic, and perceived change in external conditions due to the pandemic were examined as potential risk or protective factors. Interestingly, only small differences emerged between families of children with and without AD or between subsamples: families of children with AD and families in out-of-home care were affected slightly more, but in few domains. Improvements and deteriorations in treatment-related effects balanced each other out. Overall, the most stable and strongest risk factor for COVID-19-related stress was perceived negative change in external conditions—particularly family conditions and leisure options. Additionally, caregiver characteristics emerged as risk factors across most models. Actions to support families during the pandemic should, therefore, facilitate external conditions and focus on caregiver characteristic to reduce familial COVID-19-related stress. Trial registration: German Clinical Trials Register (DRKS), ADOPT Online: DRKS00014963 registered 27 June 2018, ADOPT Treatment: DRKS00013317 registered 27 September 2018, ADOPT Institution: DRKS00014581 registered 04 July 2018

    Resting state EEG power spectrum and functional connectivity in autism: a cross-sectional analysis

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    BACKGROUND: Understanding the development of the neuronal circuitry underlying autism spectrum disorder (ASD) is critical to shed light into its etiology and for the development of treatment options. Resting state EEG provides a window into spontaneous local and long-range neuronal synchronization and has been investigated in many ASD studies, but results are inconsistent. Unbiased investigation in large and comprehensive samples focusing on replicability is needed. METHODS: We quantified resting state EEG alpha peak metrics, power spectrum (PS, 2-32&nbsp;Hz) and functional connectivity (FC) in 411 children, adolescents and adults (n = 212 ASD, n = 199 neurotypicals [NT], all with IQ &gt; 75). We performed analyses in source-space using individual head models derived from the participants' MRIs. We tested for differences in mean and variance between the ASD and NT groups for both PS and FC using linear mixed effects models accounting for age, sex, IQ and site effects. Then, we used machine learning to assess whether a multivariate combination of EEG features could better separate ASD and NT participants. All analyses were embedded within a train-validation approach (70%-30% split). RESULTS: In the training dataset, we found an interaction between age and group for the reactivity to eye opening (p = .042 uncorrected), and a significant but weak multivariate ASD vs. NT classification performance for PS and FC (sensitivity 0.52-0.62, specificity 0.59-0.73). None of these findings replicated significantly in the validation dataset, although the effect size in the validation dataset overlapped with the prediction interval from the training dataset. LIMITATIONS: The statistical power to detect weak effects-of the magnitude of those found in the training dataset-in the validation dataset is small, and we cannot fully conclude on the reproducibility of the training dataset's effects. CONCLUSIONS: This suggests that PS and FC values in ASD and NT have a strong overlap, and that differences between both groups (in both mean and variance) have, at best, a small effect size. Larger studies would be needed to investigate and replicate such potential effects
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