63 research outputs found
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TiO2/Ferroelectric Heterostructures as Dynamic Polarization-Promoted Catalysts for Photochemical and Electrochemical Oxidation of Water
Using first-principles density functional theory calculations, we explore the chemical activity of epitaxial heterostructures of TiO2 anatase on strained polar SrTiO3 films focusing on the oxygen evolution reaction (OER), the bottleneck of water splitting. Our results show that the reactivity of the TiO2 surface is tuned by electric dipoles dynamically induced by the adsorbed species during the intermediate steps of the reaction while the initial and final steps remain unaffected. Compared to the OER on unsupported TiO2, the combined effects of the dynamically induced dipoles and epitaxial strain strongly reduce rate-limiting thermodynamic barriers and significantly improve the efficiency of the reaction.open5
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Reply to: New Meta- and Mega-analyses of Magnetic Resonance Imaging Findings in Schizophrenia: Do They Really Increase Our Knowledge About the Nature of the Disease Process?
This work was supported by National Institute of Biomedical Imaging and Bioengineering Grant No. U54EB020403 (to the ENIGMA consortium)
Characterizing a World Within the Hot-Neptune Desert: Transit Observations of LTT 9779 b with the Hubble Space Telescope/WFC3
We present an atmospheric analysis of LTT 9779 b, a rare planet situated in the hot-Neptune desert, that has been observed with Hubble Space Telescope (HST)/WFC3 with G102 and G141. The combined transmission spectrum, which covers 0.8â1.6 ÎŒm, shows a gradual increase in transit depth with wavelength. Our preferred atmospheric model shows evidence for H2O, CO2, and FeH with a significance of 3.1Ï, 2.4Ï, and 2.1Ï, respectively. In an attempt to constrain the rate of atmospheric escape for this planet, we search for the 1.083 ÎŒm helium line in the G102 data but find no evidence of excess absorption that would indicate an escaping atmosphere using this tracer. We refine the orbital ephemerides of LTT 9779 b using our HST data and observations from TESS, searching for evidence of orbital decay or apsidal precession, which are not found. The phase-curve observation of LTT 9779 b with JWST NIRISS should provide deeper insights into the atmosphere of this planet and the expected atmospheric escape might be detected with further observations concentrated on other tracers such as Lyα
Characterising a World Within the Hot Neptune Desert: Transit Observations of LTT 9779 b with HST WFC3
We present an atmospheric analysis of LTT 9779 b, a rare planet situated in
the hot Neptune desert, that has been observed with HST WFC3 G102 and G141. The
combined transmission spectrum, which covers 0.8 - 1.6 m, shows a gradual
increase in transit depth with wavelength. Our preferred atmospheric model
shows evidence for HO, CO and FeH with a significance of
3.1 , 2.4 and 2.1 , respectively. In an attempt to
constrain the rate of atmospheric escape for this planet, we search for the
1.083 m Helium line in the G102 data but find no evidence of excess
absorption that would indicate an escaping atmosphere using this tracer. We
refine the orbital ephemerides of LTT 9779 b using our HST data and
observations from TESS, searching for evidence of orbital decay or apsidal
precession, which is not found. The phase-curve observation of LTT 9779 b with
JWST NIRISS should provide deeper insights into the atmosphere of this planet
and the expected atmospheric escape might be detected with further observations
concentrated on other tracers such as Lyman .Comment: Accepted for publication in A
Positive symptoms associate with cortical thinning in the superior temporal gyrus via the ENIGMA-Schizophrenia consortium
Objective: Based on the role of the superior temporal gyrus (STG) in auditory processing, language comprehension and self-monitoring, this study aimed to investigate the relationship between STG cortical thickness and positive symptom severity in schizophrenia. Method: This prospective meta-analysis includes data from 1987 individuals with schizophrenia collected at seventeen centres around the world that contribute to the ENIGMA Schizophrenia Working Group. STG thickness measures were extracted from T1-weighted brain scans using FreeSurfer. The study performed a meta-analysis of effect sizes across sites generated by a model predicting left or right STG thickness with a positive symptom severity score (harmonized SAPS or PANSS-positive scores), while controlling for age, sex and site. Secondary models investigated relationships between antipsychotic medication, duration of illness, overall illness severity, handedness and STG thickness. Results: Positive symptom severity was negatively related to STG thickness in both hemispheres (left: ÎČstd = â0.052; P = 0.021; right: ÎČstd = â0.073; P = 0.001) when statistically controlling for age, sex and site. This effect remained stable in models including duration of illness, antipsychotic medication or handedness. Conclusion: Our findings further underline the important role of the STG in hallmark symptoms in schizophrenia. These findings can assist in advancing insight into symptom-relevant pathophysiological mechanisms in schizophrenia
Brain-Age Prediction: Systematic Evaluation of Site Effects, and Sample Age Range and Size
Structural neuroimaging data have been used to compute an estimate of the biological age of the brain (brainâage) which has been associated with other biologically and behaviorally meaningful measures of brain development and aging. The ongoing research interest in brainâage has highlighted the need for robust and publicly available brainâage models preâtrained on data from large samples of healthy individuals. To address this need we have previously released a developmental brainâage model. Here we expand this work to develop, empirically validate, and disseminate a preâtrained brainâage model to cover most of the human lifespan. To achieve this, we selected the bestâperforming model after systematically examining the impact of seven site harmonization strategies, age range, and sample size on brainâage prediction in a discovery sample of brain morphometric measures from 35,683 healthy individuals (age range: 5â90âyears; 53.59% female). The preâtrained models were tested for crossâdataset generalizability in an independent sample comprising 2101 healthy individuals (age range: 8â80âyears; 55.35% female) and for longitudinal consistency in a further sample comprising 377 healthy individuals (age range: 9â25âyears; 49.87% female). This empirical examination yielded the following findings: (1) the accuracy of age prediction from morphometry data was higher when no site harmonization was applied; (2) dividing the discovery sample into two ageâbins (5â40 and 40â90âyears) provided a better balance between model accuracy and explained age variance than other alternatives; (3) model accuracy for brainâage prediction plateaued at a sample size exceeding 1600 participants. These findings have been incorporated into CentileBrain (https://centilebrain.org/#/brainAGE2), an openâscience, webâbased platform for individualized neuroimaging metrics
Brain-Age Prediction: Systematic Evaluation of Site Effects, and Sample Age Range and Size
Structural neuroimaging data have been used to compute an estimate of the biological age of the brain (brainâage) which has been associated with other biologically and behaviorally meaningful measures of brain development and aging. The ongoing research interest in brainâage has highlighted the need for robust and publicly available brainâage models preâtrained on data from large samples of healthy individuals. To address this need we have previously released a developmental brainâage model. Here we expand this work to develop, empirically validate, and disseminate a preâtrained brainâage model to cover most of the human lifespan. To achieve this, we selected the bestâperforming model after systematically examining the impact of seven site harmonization strategies, age range, and sample size on brainâage prediction in a discovery sample of brain morphometric measures from 35,683 healthy individuals (age range: 5â90âyears; 53.59% female). The preâtrained models were tested for crossâdataset generalizability in an independent sample comprising 2101 healthy individuals (age range: 8â80âyears; 55.35% female) and for longitudinal consistency in a further sample comprising 377 healthy individuals (age range: 9â25âyears; 49.87% female). This empirical examination yielded the following findings: (1) the accuracy of age prediction from morphometry data was higher when no site harmonization was applied; (2) dividing the discovery sample into two ageâbins (5â40 and 40â90âyears) provided a better balance between model accuracy and explained age variance than other alternatives; (3) model accuracy for brainâage prediction plateaued at a sample size exceeding 1600 participants. These findings have been incorporated into CentileBrain (https://centilebrain.org/#/brainAGE2), an openâscience, webâbased platform for individualized neuroimaging metrics
Cortical brain abnormalities in 4474 individuals with schizophrenia and 5098 control subjects via the enhancing neuro Imaging genetics through meta analysis (ENIGMA) Consortium
BACKGROUND: The profile of cortical neuroanatomical abnormalities in schizophrenia is not fully understood, despite hundreds of published structural brain imaging studies. This study presents the first meta-analysis of cortical thickness and surface area abnormalities in schizophrenia conducted by the ENIGMA (Enhancing Neuro Imaging Genetics through Meta Analysis) Schizophrenia Working Group.
METHODS: The study included data from 4474 individuals with schizophrenia (mean age, 32.3 years; range, 11-78 years; 66% male) and 5098 healthy volunteers (mean age, 32.8 years; range, 10-87 years; 53% male) assessed with standardized methods at 39 centers worldwide.
RESULTS: Compared with healthy volunteers, individuals with schizophrenia have widespread thinner cortex (left/right hemisphere: Cohen's d = -0.530/-0.516) and smaller surface area (left/right hemisphere: Cohen's d = -0.251/-0.254), with the largest effect sizes for both in frontal and temporal lobe regions. Regional group differences in cortical thickness remained significant when statistically controlling for global cortical thickness, suggesting regional specificity. In contrast, effects for cortical surface area appear global. Case-control, negative, cortical thickness effect sizes were two to three times larger in individuals receiving antipsychotic medication relative to unmedicated individuals. Negative correlations between age and bilateral temporal pole thickness were stronger in individuals with schizophrenia than in healthy volunteers. Regional cortical thickness showed significant negative correlations with normalized medication dose, symptom severity, and duration of illness and positive correlations with age at onset.
CONCLUSIONS: The findings indicate that the ENIGMA meta-analysis approach can achieve robust findings in clinical neuroscience studies; also, medication effects should be taken into account in future genetic association studies of cortical thickness in schizophrenia
The Association Between Familial Risk and Brain Abnormalities Is Disease Specific: An ENIGMA-Relatives Study of Schizophrenia and Bipolar Disorder
Background: Schizophrenia and bipolar disorder share genetic liability, and some structural brain abnormalities are common to both conditions. First-degree relatives of patients with schizophrenia (FDRs-SZ) show similar brain abnormalities to patients, albeit with smaller effect sizes. Imaging findings in first-degree relatives of patients with bipolar disorder (FDRs-BD) have been inconsistent in the past, but recent studies report regionally greater volumes compared with control subjects. Methods: We performed a meta-analysis of global and subcortical brain measures of 6008 individuals (1228 FDRs-SZ, 852 FDRs-BD, 2246 control subjects, 1016 patients with schizophrenia, 666 patients with bipolar disorder) from 34 schizophrenia and/or bipolar disorder family cohorts with standardized methods. Analyses were repeated with a correction for intracranial volume (ICV) and for the presence of any psychopathology in the relatives and control subjects. Results: FDRs-BD had significantly larger ICV (d = +0.16, q <.05 corrected), whereas FDRs-SZ showed smaller thalamic volumes than control subjects (d = â0.12, q <.05 corrected). ICV explained the enlargements in the brain measures in FDRs-BD. In FDRs-SZ, after correction for ICV, total brain, cortical gray matter, cerebral white matter, cerebellar gray and white matter, and thalamus volumes were significantly smaller; the cortex was thinner (d < â0.09, q <.05 corrected); and third ventricle was larger (d = +0.15, q <.05 corrected). The findings were not explained by psychopathology in the relatives or control subjects. Conclusions: Despite shared genetic liability, FDRs-SZ and FDRs-BD show a differential pattern of structural brain abnormalities, specifically a divergent effect in ICV. This may imply that the neurodevelopmental trajectories leading to brain anomalies in schizophrenia or bipolar disorder are distinct
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