220 research outputs found

    A New Control Interaction Phenomenon in Large-Scale Type-4 Wind Park

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    ABSTRACT: This paper demonstrates the risk of a new control interaction phenomenon between a large- scale type-4 wind park (WP) and a 500 kV transmission grid at super-synchronous frequency range. This study aims at (i) using the impedance-based stability assessment (IBSA) method to investigate this new interaction phenomenon; and (ii) analyzing the impact of various transmission grid topologies, WP operating conditions as well as wind turbine (WT) converter control parameters on the severity of the interaction. For ultimate accuracy, the frequency-dependent impedance characteristics of the WP are extracted using the electromagnetic transient (EMT)-type impedance scanning instead of simplified analytical model. The performed analyses demonstrate that the WP generation capacity, length of the transmission lines, applied series and shunt compensation levels, presence of parallel lines, and grid side converter (GSC) control parameters of the WT, can significantly affect the identified control interaction risk. The obtained results are validated through detailed EMT simulations. Although the type-4 WP is considered in this paper, the presented results can be generalized to any inverter-based resource (IBR) with full-size converter (FSC), such as photovoltaic (PV) power stations

    Radionuclide profiles and recent earthquakes history of Lake Hazar Pull-apart basin (East Anatolian Fault, Turkey)

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    In Turkey, the continuous Pull-apart sediment records constitute powerful chronometers for tracking environmental perturbations such as earthquakes. In South-east Turkey, the East Anatolian Fault (EAF) is a major strike-slip fault along which large earthquakes (Ms > 7) occurred in the 19e century. According to chronicles, the seismicity of this area has been minimal for most of the last century; the latest surface rupturing earthquakes may be the Ms = 7.1 in AD 1874 and the Ms = 6.7 in AD 1875. The EAF consists of two large surface rupturing segments interrupted by a pull-apart basin at Lake Hazar (the Sincik/Lake Hazar and the Lake Hazar/Palu segments). In this geological context, the present project seeks to assess: 1) the recent sedimentation rates of Lake Hazar main Pull-apart system located on the EAF; 2) the occurrence of recent past earthquakes along the EAF. For these purposes, we use a diverse array of complementary techniques involving sediment coring, and radionuclide profiles of sediment cores. Here, we present the first results obtained within the framework of a EU-project focusing on the “seismic cycles” in Turkey (“Understanding the irregularity of seismic cycles: A case study in Turkey”). We present 210Pb and 137 Cs age models obtained from a series of short sediment cores. The radionuclide profiles are utilized for both, annual sediment rates estimates, and for tracking the historic earthquakes. The correlation between several cores and the comparison between radionuclide profiles and preliminary sedimentological data shows that sedimentary structures induced by the last AD 1874 and 1875 earthquakes can be detected by ultra-high resolution X-ray radiographies. However, our results show the presence of an additional hypothetic event in the early 20e century. These first results will be further utilized for tracking past earthquakes in longer Lake Hazar sediment time series

    The International Workshop on Osteoarthritis Imaging Knee MRI Segmentation Challenge: A Multi-Institute Evaluation and Analysis Framework on a Standardized Dataset

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    Purpose: To organize a knee MRI segmentation challenge for characterizing the semantic and clinical efficacy of automatic segmentation methods relevant for monitoring osteoarthritis progression. Methods: A dataset partition consisting of 3D knee MRI from 88 subjects at two timepoints with ground-truth articular (femoral, tibial, patellar) cartilage and meniscus segmentations was standardized. Challenge submissions and a majority-vote ensemble were evaluated using Dice score, average symmetric surface distance, volumetric overlap error, and coefficient of variation on a hold-out test set. Similarities in network segmentations were evaluated using pairwise Dice correlations. Articular cartilage thickness was computed per-scan and longitudinally. Correlation between thickness error and segmentation metrics was measured using Pearson's coefficient. Two empirical upper bounds for ensemble performance were computed using combinations of model outputs that consolidated true positives and true negatives. Results: Six teams (T1-T6) submitted entries for the challenge. No significant differences were observed across all segmentation metrics for all tissues (p=1.0) among the four top-performing networks (T2, T3, T4, T6). Dice correlations between network pairs were high (>0.85). Per-scan thickness errors were negligible among T1-T4 (p=0.99) and longitudinal changes showed minimal bias (<0.03mm). Low correlations (<0.41) were observed between segmentation metrics and thickness error. The majority-vote ensemble was comparable to top performing networks (p=1.0). Empirical upper bound performances were similar for both combinations (p=1.0). Conclusion: Diverse networks learned to segment the knee similarly where high segmentation accuracy did not correlate to cartilage thickness accuracy. Voting ensembles did not outperform individual networks but may help regularize individual models.Comment: Submitted to Radiology: Artificial Intelligence; Fixed typo

    Up-regulation of NMDA receptor subunit and post-synaptic density protein expression in the thalamus of elderly patients with schizophrenia

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    Numerous studies have described structural and functional abnormalities of the thalamus in schizophrenia, but surprisingly few studies have examined neurochemical abnormalities that accompany these pathological changes. We previously identified abnormalities of multiple molecules associated with glutamatergic neurotransmission, including changes in NMDA receptor subunit transcripts and binding sites and NMDA receptor-associated post-synaptic density (PSD) protein transcripts in the thalamus of elderly patients with schizophrenia. In the present study, we performed western blot analysis to determine whether protein levels of NMDA receptor subunits (NR1, NR2A, NR2B) and associated PSD proteins (NF-L, PSD95, SAP102) are altered in schizophrenia. Thalamic tissue from each subject was grossly dissected into two regions: a dorsomedial region containing limbic-associated dorsomedial, anterior and central medial thalamic nuclei; and a ventral thalamus region that primarily consisted of the ventral lateral nucleus. We observed increased protein expression of the NR2B NMDA receptor subunit and its associated intracellular protein, PSD95, in the dorsomedial thalamus of patients with schizophrenia, but the other molecules were unchanged, and we found no changes in the ventral thalamus. These data provide additional evidence of thalamic neurochemical abnormalities, particularly in thalamic nuclei which project to limbic regions of the brain. Further, these findings provide additional evidence of NMDA receptor alterations in schizophrenia, which may play an important role in the neurobiology of the illness.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65970/1/j.1471-4159.2006.03954.x.pd

    Urban living in healthy Tanzanians is associated with an inflammatory status driven by dietary and metabolic changes

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    Sub-Saharan Africa currently experiences an unprecedented wave of urbanization, which has important consequences for health and disease patterns. This study aimed to investigate and integrate the immune and metabolic consequences of rural or urban lifestyles and the role of nutritional changes associated with urban living. In a cohort of 323 healthy Tanzanians, urban as compared to rural living was associated with a pro-inflammatory immune phenotype, both at the transcript and protein levels. We identified different food-derived and endogenous circulating metabolites accounting for these differences. Serum from urban dwellers induced reprogramming of innate immune cells with higher tumor necrosis factor production upon microbial re-stimulation in an in vitro model of trained immunity. These data demonstrate important shifts toward an inflammatory phenotype associated with an urban lifestyle and provide new insights into the underlying dietary and metabolic factors, which may affect disease epidemiology in sub-Sahara African countries. Rapid urbanization can be associated with adverse health implications. de Mast and colleagues compare urban and rural Tanzanian populations using multi-omics and observe that urbanization is associated with an elevated but reversible inflammatory state

    Class in contemporary Britain: comparing the Cultural Capital and Social Exclusion (CCSE) project and the Great British Class Survey (GBCS)

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    The paper discusses the salience of class in Britain in relation to the experiment of the BBC–academic partnership of the Great British Class Survey (GBCS). It addresses the claimed inauguration of a third phase in class analysis in the UK sparked by the experiment. This is done by considering three main issues. First, the GBCS experiment is situated in the context of various explorations of cultural class analyses, and chiefly in relation to the Cultural Capital and Social Exclusion (CCSE) project (ESRC funded 2003–6). Secondly, the focus is on the influence of the academic turn to big data for the procedures and claims of the project, and some implications of the methodological choices. Thirdly, attention is turned to the deleterious effects of commercial and institutional pressures on the current research culture in which the experiment exists

    Epigenomic Profiling of Human CD4+ T Cells Supports a Linear Differentiation Model and Highlights Molecular Regulators of Memory Development

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    SummaryThe impact of epigenetics on the differentiation of memory T (Tmem) cells is poorly defined. We generated deep epigenomes comprising genome-wide profiles of DNA methylation, histone modifications, DNA accessibility, and coding and non-coding RNA expression in naive, central-, effector-, and terminally differentiated CD45RA+ CD4+ Tmem cells from blood and CD69+ Tmem cells from bone marrow (BM-Tmem). We observed a progressive and proliferation-associated global loss of DNA methylation in heterochromatic parts of the genome during Tmem cell differentiation. Furthermore, distinct gradually changing signatures in the epigenome and the transcriptome supported a linear model of memory development in circulating T cells, while tissue-resident BM-Tmem branched off with a unique epigenetic profile. Integrative analyses identified candidate master regulators of Tmem cell differentiation, including the transcription factor FOXP1. This study highlights the importance of epigenomic changes for Tmem cell biology and demonstrates the value of epigenetic data for the identification of lineage regulators

    Wiring of Photosystem II to Hydrogenase for Photoelectrochemical Water Splitting.

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    In natural photosynthesis, light is used for the production of chemical energy carriers to fuel biological activity. The re-engineering of natural photosynthetic pathways can provide inspiration for sustainable fuel production and insights for understanding the process itself. Here, we employ a semiartificial approach to study photobiological water splitting via a pathway unavailable to nature: the direct coupling of the water oxidation enzyme, photosystem II, to the H2 evolving enzyme, hydrogenase. Essential to this approach is the integration of the isolated enzymes into the artificial circuit of a photoelectrochemical cell. We therefore developed a tailor-made hierarchically structured indium-tin oxide electrode that gives rise to the excellent integration of both photosystem II and hydrogenase for performing the anodic and cathodic half-reactions, respectively. When connected together with the aid of an applied bias, the semiartificial cell demonstrated quantitative electron flow from photosystem II to the hydrogenase with the production of H2 and O2 being in the expected two-to-one ratio and a light-to-hydrogen conversion efficiency of 5.4% under low-intensity red-light irradiation. We thereby demonstrate efficient light-driven water splitting using a pathway inaccessible to biology and report on a widely applicable in vitro platform for the controlled coupling of enzymatic redox processes to meaningfully study photocatalytic reactions.This work was supported by the U.K. Engineering and Physical Sciences Research Council (EP/H00338X/2 to E.R. and EP/G037221/1, nanoDTC, to D.M.), the UK Biology and Biotechnological Sciences Research Council (BB/K002627/1 to A.W.R. and BB/K010220/1 to E.R.), a Marie Curie Intra-European Fellowship (PIEF-GA-2013-625034 to C.Y.L), a Marie Curie International Incoming Fellowship (PIIF-GA-2012-328085 RPSII to J.J.Z) and the CEA and the CNRS (to J.C.F.C.). A.W.R. holds a Wolfson Merit Award from the Royal Society.This is the final version of the article. It first appeared from ACS Publications via http://dx.doi.org/10.1021/jacs.5b0373

    Evidence, and replication thereof, that molecular-genetic and environmental risks for psychosis impact through an affective pathway

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    Background There is evidence that environmental and genetic risk factors for schizophrenia spectrum disorders are transdiagnostic and mediated in part through a generic pathway of affective dysregulation. Methods We analysed to what degree the impact of schizophrenia polygenic risk (PRS-SZ) and childhood adversity (CA) on psychosis outcomes was contingent on co-presence of affective dysregulation, defined as significant depressive symptoms, in (i) NEMESIS-2 (n = 6646), a representative general population sample, interviewed four times over nine years and (ii) EUGEI (n = 4068) a sample of patients with schizophrenia spectrum disorder, the siblings of these patients and controls. Results The impact of PRS-SZ on psychosis showed significant dependence on co-presence of affective dysregulation in NEMESIS-2 [relative excess risk due to interaction (RERI): 1.01, p = 0.037] and in EUGEI (RERI = 3.39, p = 0.048). This was particularly evident for delusional ideation (NEMESIS-2: RERI = 1.74, p = 0.003; EUGEI: RERI = 4.16, p = 0.019) and not for hallucinatory experiences (NEMESIS-2: RERI = 0.65, p = 0.284; EUGEI: -0.37, p = 0.547). A similar and stronger pattern of results was evident for CA (RERI delusions and hallucinations: NEMESIS-2: 3.02, p < 0.001; EUGEI: 6.44, p < 0.001; RERI delusional ideation: NEMESIS-2: 3.79, p < 0.001; EUGEI: 5.43, p = 0.001; RERI hallucinatory experiences: NEMESIS-2: 2.46, p < 0.001; EUGEI: 0.54, p = 0.465). Conclusions The results, and internal replication, suggest that the effects of known genetic and non-genetic risk factors for psychosis are mediated in part through an affective pathway, from which early states of delusional meaning may arise
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