Explore the vast range of titles available.

In this study, scale interaction between synoptic eddies and low‐frequency flow is investigated. The synoptic eddy feedback is a key process in sustaining the low‐frequency flow. We show clear evidence using NCEP reanalysis data that there is a general underlying rule—the “left‐hand rule”, governing the synoptic eddy feedback onto low‐frequency flow. This rule states that eddy‐vorticity fluxes are directed preferentially about 90 degrees toward their left‐hand side, so that they converge into cyclonic flow and diverge from anticyclonic flow. Therefore, the eddy vorticity flux plays a positive role in reinforcing low‐frequency flow.

Although previous neuroimaging evidence has confirmed the brain functional disturbances in thyroid‐associated ophthalmopathy (TAO), the dynamic characteristics of brain activity and functional connectivity (FC) in TAO were rarely concerned. The present study aims to investigate the alterations of temporal variability of brain activity and FC in TAO using resting‐state functional magnetic resonance imaging (rs‐fMRI). Forty‐seven TAO patients and 30 age‐, gender‐, education‐, and handedness‐matched healthy controls (HCs) were enrolled and underwent rs‐fMRI scanning. The dynamic amplitude of low‐frequency fluctuation (dALFF) was first calculated using a sliding window approach to characterize the temporal variability of brain activity. Based on the dALFF results, seed‐based dynamic functional connectivity (dFC) analysis was performed to identify the temporal variability of efficient communication between brain regions in TAO. Additionally, correlations between dALFF and dFC and the clinical indicators were analyzed. Compared with HCs, TAO patients displayed decreased dALFF in the left superior occipital gyrus (SOG) and cuneus (CUN), while showing increased dALFF in the left triangular part of inferior frontal gyrus (IFGtriang), insula (INS), orbital part of inferior frontal gyrus (ORBinf), superior temporal gyrus (STG) and temporal pole of superior temporal gyrus (TPOsup). Furthermore, TAO patients exhibited decreased dFC between the left STG and the right middle occipital gyrus (MOG), as well as decreased dFC between the left TPOsup and the right calcarine fissure and surrounding cortex (CAL) and MOG. Correlation analyses showed that the altered dALFF in the left SOG/CUN was positively related to visual acuity (r = .409, p = .004), as well as the score of QoL for visual functioning (r = .375, p = .009). TAO patients developed abnormal temporal variability of brain activity in areas related to vision, emotion, and cognition, as well as reduced temporal variability of FC associated with vision deficits. These findings provided additional insights into the neurobiological mechanisms of TAO. We explored the spatiotemporal alterations of both brain activity and connectivity in thyroid‐associated ophthalmopathy (TAO) by using dynamic amplitude of low‐frequency fluctuation and dynamic functional connectivity, respectively. We also identified correlations between the abnormal dynamic brain activity in the left occipital area and the visual deficits in TAO patients.

Obsessive–compulsive disorder (OCD) displays alterations in regional brain activity represented by the amplitude of low‐frequency fluctuation (ALFF), but the time‐varying characteristics of this local neural activity remain to be clarified. We aimed to investigate the dynamic changes of intrinsic brain activity in a relatively large sample of drug‐naïve OCD patients using univariate and multivariate analyses. We applied a sliding‐window approach to calculate the dynamic ALFF (dALFF) and compared the difference between 73 OCD patients and age‐ and sex‐matched healthy controls (HCs). We also utilized multivariate pattern analysis to determine whether dALFF could differentiate OCD patients from HCs at the individual level. Compared with HCs, OCD patients exhibited increased dALFF mainly within regions of the cortical–striatal–thalamic–cortical (CSTC) circuit, including the bilateral dorsal anterior cingulate cortex, medial prefrontal cortex and striatum, and right dorsolateral prefrontal cortex (dlPFC). Decreased dALFF was identified in the bilateral inferior parietal lobule (IPL), posterior cingulate cortex, insula, fusiform gyrus, and cerebellum. Moreover, we found negative correlations between illness duration and dALFF values in the right IPL and between dALFF values in the left cerebellum and Hamilton Depression Scale scores. Furthermore, dALFF can distinguish OCD patients from HCs with the most discriminative regions located in the IPL, dlPFC, middle occipital gyrus, and cuneus. Taken together, in the current study, we demonstrated a characteristic pattern of higher variability of regional brain activity within the CSTC circuits and lower variability in regions outside the CSTC circuits in drug‐naïve OCD patients. We used the dynamic amplitude of low‐frequency fluctuation to determine the temporal variability properties of regional brain activity. We demonstrated a characteristic pattern of higher time‐varying intrinsic activity within the cortical–striatal–thalamic–cortical circuits and lower variability in regions outside the circuits in drug‐naïve obsessive–compulsive disorder (OCD) patients. We emphasize that the dysfunction of regions outside the cortical–striatal–thalamic–cortical circuits, particularly the parietal cortex and cerebellum, plays an important role in the pathophysiology of OCD. ​

The brain's response to external events depends on its internal arousal states, which are dynamically governed by neuromodulatory systems and have recently been linked to coordinated spike timing cascades in widespread brain networks. At rest, both arousal fluctuations and spiking cascades are evident throughout the forebrain and play out over multisecond time scales. Here, by analyzing large‐scale neural recording data collected by the Allen Institute, it is demonstrated that these intrinsic processes persist across the mouse brain even during periods of continuous visual stimulation. In the stationary animal, each quasi‐periodic cascade cycle systematically influenced 1) the efficacy of encoding in visually responsive brain areas and 2) the incidence of memory‐related hippocampal ripples. During this cycle, the phase of high arousal is marked by high efficiency in visual encoding whereas the phase of low arousal is marked by the occurrence of hippocampal ripples. However, during bouts of active locomotion, this cycle is abolished and brain maintained a state of elevated visual coding efficiency, with ripples being nearly absent. It is hypothesized that the infra‐slow cascade dynamics reflect an adaptive cycle of alternating exteroceptive sensory sampling and internal mnemonic function that persistently pervades the forebrain, only stopping during active exploration of the environment. This study reveals widespread, coordinated brain activity during passive visual stimulation in mice. Sensory coding, phase‐locked with the periodic dynamics, shows an inverse relationship to hippocampal ripples. The results suggest that periodic brain activity spurs alteration between two distinct operational modes of brain, facilitating exteroceptive sensory sampling and internal mnemonic processes, respectively.

Digital twins efficiency lies in fast and representative solutions of inverse problems to accomodate models with physical observations. The quality of the solution of an inverse problem is conditioned by inherent features of the latter, in particular (i) the richness of available data, (ii) the a priori experimental and modeling knowledge that allows to regularize the ill-posedness nature of the problem, and (iii) the complexity of the space in which updated parameters are sought. We present in this contribution a fully automated physics-guided model updating framework dedicated to the correction of finite element models from low-frequency dynamics measurements. The proposed methodology is based on the minimization of a modified Constitutive Relation Error (mCRE) functional, whose basic idea is to construct mechanical fields and identify material parameters that are a trade-off between all available information (and associated confidence) but without any further assumption. The dependency into some expert-user’s judgment is thus avoided. Dedicated rules are provided to automatically calibrate all mCRE internal tuning parameters as well as a strategy to optimize the space in which parameters are sought, leading to a fully autonomous algorithm. The performance and robustness of the proposed model updating methodology are illustrated using synthetic ground motion tests on a bending plate in which defects of various shapes are identified from noisy acceleration datasets, with inherent limitations due to richness of input loading, sensors sparsity and defect identifiability.

Minimal hepatic encephalopathy (MHE) is the initial stage of hepatic encephalopathy (HE), MHE patients have associated with widespread neuro-psychological impairment. Liver transplantation (LT) can restore metabolic abnormalities but the mechanisms are unclear. This study aimed to longitudinally evaluate brain function alteration in MHE patients one month after LT and their correlation with cognitive changes by using resting-state functional magnetic resonance imaging (rs-fMRI). Rs-fMRI data was collected from 32 healthy controls and 27 MHE before and 1 month after LT. Between-group comparisons of demographic data and neuropsychological scores were analyzed using SPSS 25.0. Functional imaging data were analyzed using RESTplus and SPM12 software based on MATLAB 2017b. Gender, age, and years of education were used as covariates to obtain low-frequency fluctuationd (ALFF) and dynamic low-frequency fluctuation (dALFF) dindices. Correlation analyses were performed to explore the relationship between the change of ALFF and dALFF with the change of clinical indexes pre- and post-LT. Compared to controls, ALFF values increased in the Left Cerebelum 8, right orbital part of the inferior frontal gyrus (ORBinf), right superior occipital gyrus (SOG) and decreased in right PreCG and left middle frontal gyrus (MFG) in patients post-LT; dALFF values increased in the right temporal pole and middle temporal gyrus (TPOmid), right ORBinf, left caudate nucleus (CAU), right SOG and decreased in left PreCG, left PCUN, left ANG, left SMA and left MFG in patients post-LT. Compared to pre-LT, ALFF values of post-LT patients increased in the right calcarine fissure and surrounding cortex (CAL), right MOG and decreased in right cerebelum 8, left PCUN; dALFF values of post-LT patients decreased in right thalamus (THA), left posterior cingulate gyrus (PCG) and left MFG. The changes of ALFF in the left PCUN, right CAL and right MOG were correlated with change of digit symbol test (DST) scores ( P < 0.05). In summary, this study not only showcases the potential of ALFF/dALFF algorithms for assessing alterations in spontaneous neural activity in MHE, but also provides new insights into the altered brain functions in MHE patients 1 month after LT, which may facilitate the elucidation of elucidation of mechanisms underlying cognitive restoration post-LT in MHE patients.

patients with acute basal ganglia ischemic stroke (BGIS) show changes in local brain activity represented by the amplitude of low-frequency fluctuation (ALFF), but the time-varying characteristics of this local nerve activity are still unclear. This study aimed to investigate the abnormal time-varying local brain activity of patients with acute BGIS by using the ALFF method combined with the sliding-window approach. In this study, 34 patients with acute BGIS with motor dysfunction and 44 healthy controls (HCs) were recruited. The dynamic amplitude of low-frequency fluctuation (dALFF) was employed to detect the alterations in brain activity induced by acute BGIS patients. A two-sample -test comparison was performed to compare the dALFF value between the two groups and a Spearman correlation analysis was conducted to assess the relationship between the local brain activity abnormalities and clinical characteristics. Compared with HCs, the activity of neurons in the left temporal pole (TP), parahippocampal gyrus (paraHIP), middle occipital gyrus (MOG), dorsolateral superior frontal gyrus (SFGdl), medial cingulate cortex (MCC), right rectus, precuneus (PCu) and right cerebellum crus1 were significantly increased in patients with BGIS. In addition, we found that there was a negative correlation (  = -0.458,  = 0.007) between the dALFF value of the right rectus and the scores of the National Institutes of Health Stroke Scale (NIHSS), and a positive correlation (  = 0.488, 0.499,  < 0.05) with the scores of the Barthel Index scale (BI) and the Fugl Meyer motor function assessment (FMA). ROC analysis results demonstrated that the area under the curves (AUC) of the right rectus was 0.880, <0.001. The pattern of intrinsic brain activity variability was altered in patients with acute BGIS compared with HCs. The abnormal dALFF variability might be a potential tool to assess motor function in patients with acute BGIS and potentially inform the diagnosis of this disease.

Primary angle-closure glaucoma (PACG), an incurable ophthalmic disease, is a serious risk to human visual health. Previous studies have demonstrated a strong link between PACG and neuroimaging changes in the brain. This study utilizes dynamic low-frequency fluctuation amplitude (dALFF) with the aim of resolving the potential dynamic alterations in neurological function in PACG and integrating transcriptomics profiles with spatial distribution characteristics of neuromodulatory receptors/transporters to systematically elucidate the underlying neurophysiopathological mechanisms. We used sliding time windows of 30TR, 50TR and 80TR to calculate dALFF values and performed partial least squares regression (PLS) analysis of t-values after two-sample test of dALFF values under the sliding window of 50 TR against the Allen Human Brain Atlas (AHBA) to screen genes. Enrichment analysis, tissue-specific expression analysis and protein-protein interactions (PPI) network construction were implemented. The t-values were also analyzed for spatial correlation with neurotransmitter receptor/transporter density profiles distributed throughout the brain. The two-sample tests under three sliding windows revealed extensive brain alterations in PACG and each abnormal brain region showed elevation (the Gaussian Random Field method, with significance at the voxel level set at  < 0.005 (two-tailed) and at the cluster level at  < 0.01), which was mainly in the occipital lobe and angular gyrus. Enrichment analysis were mainly \"regulation of neuron projection development\" and \"membrane organization\" pathways (  < 0.05, no corrected). Specific expression analysis revealed that the relevant genes were involved in all stages of thalamic development. PPI analysis demonstrated the role of PACG-associated genes in the formation of functional network. Neurotransmitter receptor/transporter correlation analysis revealed significant associations with 5-HT4R and mGlu5R (  < 0.05, FDR corrected). The present study reveals that a wide range of brain regions in PACG patients show significant functional remodeling, elucidating the molecular regulatory network behind this type of pathological alteration.

Magnetic nanoparticles have gained attention as a potential structure for therapy and diagnosing oncological diseases. The key property of the magnetic nanoparticles is the ability to respond to an external magnetic field. It is known that magnetofection causes an increase in the cellular uptake of RNA and DNA in complexes with magnetic nanoparticles in the presence of a permanent magnetic field. However, the influence of a dynamic magnetic field on the internalization of MNPs is not clear. In this work, we propose the idea that applying external low-frequency dynamic magnetic fields may decrease the cellular uptake, such as macrophages and malignant neuroblastoma. Using fluorescence microscopy and atomic emission spectroscopy, we found that oscillating magnetic fields decreased the cellular uptake of magnetic nanoparticles compared to untreated cells by up to 46%. In SH-SY5Y tumor cells and macrophage RAW264.7 cells, the absolute values of Fe per cell differed by 0.10 pg/cell and 0.33 pg/cell between treated and untreated cells, respectively. These results can be applied in the control of the cellular uptake in different areas of biomedicine.

Bipolar disorder type II (BD-II) is linked to an increased suicidal risk. Since a prior suicide attempt (SA) is the single most important risk factor for sequent suicide, the elucidation of involved neural substrates is critical for its prevention. Therefore, we examined the spontaneous brain activity and its temporal variabilities in suicide attempters with bipolar II during a major depressive episode. In this cross-sectional study, 101 patients with BD-II, including 44 suicidal attempters and 57 non-attempters, and 60 non-psychiatric controls underwent a resting-state functional magnetic resonance imaging (fMRI). Participants were assessed with Hamilton Rating Scale for Depression (HAMD) and Nurses , Global Assessment of Suicide Risk (NGASR). The dynamics of low-frequency fluctuation (dALFF) was measured using sliding-window analysis and its correlation with suicidal risk was conducted using Pearson correlation. Compared to non-attempters, suicidal attempters showed an increase in brain activity and temporal dynamics in the anterior cingulate cortex (ACC). In addition, the temporal variabilities of ACC activity positively correlated with suicidal risk (R = 0.45, p  = 0.004), while static ACC activity failed to (R = 0.08, p  > 0.05). Our findings showed that an aberrant static ALFF and temporal variability could affect suicidal behavior in BD-II patients. However, temporal variability of neuronal activity was more sensitive than static amplitude in reflecting diathesis for suicide in BD-II. Dynamics of brain activity could be considered in developing neuromarkers for suicide prevention.