Dynamic Amplitude Research Articles

Multiplexable intrinsic Fabry-Pérot interferometers inscribed by femtosecond laser for vibration measurement in high temperature environments

This paper reports fabrication technique and demodulation algorithm developments to use multiplexable intrinsic Fabry-Pérot interferometer (IFPI) fiber sensor array for distributed vibration measurements at high temperatures. Using femtosecond laser direct writing scheme, IFPI array were fabricated through laser-induced Type II scattering points in single mode fiber cores. Reflection spectra of IFPI array were demodulated in real-time using modified Bunemen frequency analysis. The demodulation algorithm, which was implemented using a photodetector-array spectrometer, achieves 64-nε dynamic strain resolution at 1-kHz spectral acquisition rate and 2-kHz maximum vibration bandwidth. Performance and stabilities of IFPI sensor array were characterized from room temperatures to 800 °C. The static strain resolution was 0.6 με and the minimum detectable dynamic strain amplitude was 23 nε/√Hz at 800 °C. The multiplex performance was also tested by measuring dynamic strain in time domain through six IFPI sensor array fabricated in one fiber. This paper presents an integrated and low-cost sensing solution to perform distributed vibration measurements in harsh environments.

Abnormal Static and Dynamic Local-Neural Activity in COPD and Its Relationship With Pulmonary Function and Cognitive Impairments.

Patients with chronic obstructive pulmonary disease (COPD) are characterized by attenuated pulmonary function and are frequently reported with cognitive impairments, especially memory impairments. The mechanism underlying the memory impairments still remains unclear. We applied resting-state functional magnetic resonance imaging (RS-fMRI) to compare the brain local activities with static and dynamic amplitude of low-frequency fluctuations (sALFF, dALFF) among patients with COPD (n = 32) and healthy controls (HC, n = 30). Compared with HC, COPD patients exhibited decreased sALFF in the right basal ganglia and increased dALFF in the bilateral parahippocampal/hippocampal gyrus. The reduced the left basal ganglia was associated with lower oxygen partial pressure. Besides, the increased dALFF in the left hippocampal/parahippocampal cortex was associated with poor semantic-memory performance and the increased dALFF in the left hippocampal/parahippocampal cortex was associated the forced vital capacity. The present study revealed the abnormal static and dynamic local-neural activities in the basal ganglia and parahippocampal/hippocampal cortex in COPD patient and its relationship with poor lung function and semantic-memory impairments.

An Enhanced Semi-Coupled Methodology for the Analysis and Design of Floating Production Systems

Abstract This work presents an enhanced hybrid methodology for the analysis and design of floating production systems (FPS). The semi-coupled (S-C) procedure exploits the advantages of coupled and uncoupled models, incorporated into a three-stage sequence of analyses that can be fully automated within a single analysis program, presenting striking reductions of computational costs. The procedure begins by determining, through a full nonlinear static coupled analysis, the mean equilibrium position of the FPS with its mooring lines and risers. Then, it automatically evaluates equivalent six degrees-of-freedom (6DOF) stiffness matrices and force vectors representing the whole array of lines. Finally, these matrices/vectors are transferred to the dynamic analysis, solving the global 6DOF equations of motion restarted from the static equilibrium position. This way, the S-C methodology represents all nonlinear effects associated with the lines and considers their influence on the dynamic behavior of the hull. However, in some situations, it could still overestimate dynamic amplitudes of low-frequency (LF) motions and/or underestimate amplitudes of line tensions. Thus, to improve the overall accuracy, enhanced procedures are incorporated to better represent damping and inertial contribution of the lines. Results of case studies confirm that this methodology provides results adequate for preliminary or intermediary design stages.

Design of the novel ThermoBrachy applicators enabling simultaneous interstitial hyperthermia and high dose rate brachytherapy

Objective: In High Dose Rate Brachytherapy for prostate cancer there is a need for a new way of increasing cancer cell kill in combination with a stable dose to the organs at risk. In this study, we propose a novel ThermoBrachy applicator that offers the unique ability to apply interstitial hyperthermia while simultaneously serving as an afterloading catheter for high dose rate brachytherapy for prostate cancer. This approach achieves a higher thermal enhancement ratio than in sequential application of radiation and hyperthermia and has the potential to decrease the overall treatment time. Methods: The new applicator uses the principle of capacitively coupled electrodes. We performed a proof of concept experiment to demostrate the feasibility of the proposed applicator. Moreover, we used electromagnetic and thermal simulations to evaluate the power needs and temperature homogeneity in different tissues. Furthermore we investigated whether dynamic phase and amplitude adaptation can be used to improve longitudinal temperature control. Results: Simulations demonstrate that the electrodes achieve good temperature homogeneity in a homogenous phantom when following current applicator spacing guidelines. Furthermore, we demonstrate that dynamic phase and amplitude adaptation provides a great advancement for further adaptability of the heating pattern. Conclusions: This newly designed ThermoBrachy applicator has the potential to revise the interest in interstitial thermobrachytherapy, since the simultaneous application of radiation and hyperthermia enables maximum thermal enhancement and provides maximum efficiency for patient and organization.

Experimental Study on the Dynamic Modulus and Damping Ratio of Compacted Loess under Circular Dynamic Stress Paths

Dynamic loads such as earthquakes and traffic will simultaneously generate vertical dynamic stress and horizontal shear stress in the foundation soil. When the vertical dynamic stress amplitude is twice the horizontal shear dynamic stress amplitude, and the phase difference between them is 90°, a circular dynamic stress path is formed in the τzθd ~ (σzd − σθd)/2 stress coordinate system. To simulate the stress state of soil in the area of the circular dynamic stress path caused by bidirectional dynamic stress coupling, a series of tests of compacted loess under the action of a circular dynamic stress path were carried out using a hollow cylindrical torsion shear apparatus. The effects of the mean principal stress, dry density, and deviatoric stress ratio (the ratio of deviator stress to average principal stress) on the dynamic modulus and damping ratio of compacted loess were mainly studied. The test results show that, under the action of the circular dynamic stress path, the larger the mean principal stress is, the larger the dynamic compression modulus and dynamic shear modulus are. The dynamic compression modulus increases obviously with increasing dry density, but the dynamic shear modulus increases only slightly. When the deviator stress ratio increases from 0 to 0.4, the dynamic compression modulus and dynamic shear modulus increase to a certain extent. In addition, the greater the dry density and deviatoric stress ratio are, the greater the initial dynamic compression modulus and initial dynamic shear modulus of the compacted loess. The dynamic compression damping ratio of compacted loess increases with increasing mean principal stress, but the dynamic shear damping ratio decreases with increasing mean principal stress. Dry density basically has no effect on the dynamic compression damping ratio and dynamic shear damping ratio of compacted loess. When the dynamic strain exceeds 1%, the greater the deviatoric stress ratio is, the smaller the dynamic compression damping ratio and the dynamic shear damping ratio are. The research results can provide reference for the study of dynamic modulus and damping ratio of loess under special stress paths.

Temporal dynamic changes of intrinsic brain activity in Alzheimer’s disease and mild cognitive impairment patients: a resting-state functional magnetic resonance imaging study

BackgroundAlzheimer’s disease (AD) is a progressive neurodegenerative disease characterized by memory impairment. Previous studies have largely focused on alterations of static brain activity occurring in patients with AD. Few studies to date have explored the characteristics of dynamic brain activity in cognitive impairment, and their predictive ability in AD patients.MethodsOne hundred and eleven AD patients, 29 MCI patients, and 73 healthy controls (HC) were recruited. The dynamic amplitude of low-frequency fluctuation (dALFF) and the dynamic fraction amplitude of low-frequency fluctuation (dfALFF) were used to assess the temporal variability of local brain activity in patients with AD or mild cognitive impairment (MCI). Pearson’s correlation coefficients were calculated between the metrics and subjects’ behavioral scores.ResultsThe results of analysis of variance indicated that the AD, MCI, and HC groups showed significant variability of dALFF in the cerebellar posterior and middle temporal lobes. In AD patients, these brain regions had high dALFF variability. Significant dfALFF variability was found between the three groups in the left calcarine cortex and white matter. The AD group showed lower dfALFF than the MCI group in the left calcarine cortex.ConclusionsCompared to HC, AD patients were found to have increased dALFF variability in the cerebellar posterior and temporal lobes. This abnormal pattern may diminish the capacity of the cerebellum and temporal lobes to participate in the cerebrocerebellar circuits and default mode network (DMN), which regulate cognition and emotion in AD. The findings above indicate that the analysis of dALFF and dfALFF based on functional magnetic resonance imaging data may give a new insight into the neurophysiological mechanisms of AD.

A Pulse-Number-Adjustable MSPCNN and Its Image Enhancement Application

Pulse-coupled neural network (PCNN) aims to control neuronal firing state automatically and complete related image processing tasks. This paper presents a pulse-number-adjustable MSPCNN model (PNA-MSPCNN) that can automatically acquire the firing times and the firing frequency of each neuron. Hereinto, synaptic weight matrix Wijkl and decay factor α will generate an interaction value to determine the final calculation result of the internal activity U. Dynamic threshold amplitude V, step function Q, and auxiliary parameter P can precisely adjust the variation ranges of the dynamic threshold E. Additionally, we propose a low-light image enhancement method based on the above PNA-MSPCNN and a modified low-light image enhancement (LIME). The proposed LIME algorithm focuses mainly on the parameter setting method of weight matrix Wmq, which will bring further improvement of testing image contrast. Experimental results demonstrate that our proposed method achieves better low-light image enhancement performances, compared to prevalent image enhancement methods, including SSIM of 0.8725, AMBE of 0.0550, MSE of 0.0092, and PSNR of 45.7764.

Cyclic Degradation Characteristics of Undisturbed Soft Clay considering Anisotropy

The stress‐strain characteristics of soil depend primarily on the previous stress history and stress path, thus related to both the stress magnitude and direction. To have a better understanding of the response of soft clay under heart‐shaped stress paths, 18 cyclic hollow cylinders tests were performed on undisturbed Hangzhou soft clay under different cyclic stress ratios, deviatoric consolidation ratios (K0), and loading frequencies. The result shows that as the vertical dynamic stress amplitude, K0 value, and loading frequency increase, the degradation index gradually decreases. Moreover, the degradation index of the soil under the cyclic torsion shear (CTS) test is always higher than that under the cyclic triaxial (CT) test. The increase in the amplitude of the cyclic stress ratio (CSR), K0 value, and the decrease in the loading frequency will promote the initial accumulative plastic strain and accelerate the failure rate of the soil sample; it shows that the effects of cyclic stress ratio amplitude, deviatoric consolidation ratios K0, and loading frequency on the accumulative plastic deformation of soil cannot be ignored. On the basis of the test results, a logarithmic relationship between the degradation index and the loading frequency is determined. A new empirical formula of accumulative plastic strain degradation of soft clay has been established, and its accuracy has been further verified by test data. The research results can provide theories for predicting and calculating the long‐term settlement and deformation of clay foundation.

Study on Dynamic Response Characteristics of Rock Slope

After the wenchuan earthquake, the dynamic response law of rock slope under the action of dynamic load is a very concerned and urgent problem in the field of seismic engineering. This paper analyzed the dynamic response law of simplified rock slope under the cosine wave dynamic load by numerical simulation with FLAC3D software. This research emphatically analyzed the variation law of amplification coefficient of seismic displacement, acceleration and velocity of rock slope under the condition of different slope height, slope angle, dynamic load period and dynamic load amplitude, which provides a basis for reducing seismic damage of slope area and seismic design of engineering structure.

Reduction of the vibration amplitude with variable excitation frequency

AbstractIn many dynamic systems large vibration amplitudes occur if the operation frequency is near the resonance frequency. Also during the resonance passage large amplitudes result. In order to reduce the amplitude of the oscillation a suitable excitation can be applied. The force driven single degree of freedom harmonic oscillator is used to analyse the reaction of the dynamic system to a variable excitation frequency. The analysis starts with a mathematical transformation of the excitation signal in order to identify the influence of the different excitation parameters. It is shown that for specific parameters the natural frequency of the system can be eliminated from the excitation signal. In both cases, the operation near the resonance frequency and the passage through resonance, suitable numerical values, correlations between the parameters and functions can be found to reduce the resulting vibration amplitude of the system.

Abnormal Dynamics of Resting-Sate Functional Activity and Couplings in Postpartum Depression With and Without Anxiety

Postpartum depression (PPD) and PPD comorbid with anxiety (PPD-A) are very prevalent and become severe mental health problems in women after childbirth. PPD with and without anxiety shares many similar pathopsychological features leading to ongoing debates about their diagnostic and neurobiological uniqueness. The present work aims to delineate common and disorder-specific neural underpinnings and potential treatment targets for PPD and PPD-A by characterizing functional dynamics with resting-state functional magnetic resonance imaging. PPD-A showed specifically increased dynamic amplitude of low-frequency fluctuation (dALFF) in subgenual anterior cingulate cortex (sgACC) and specifically increased dynamic functional connectivity (dFC) between sgACC and superior temporal sulcus (STS). PPD exhibited specifically increased static FC (sFC) between sgACC and ventral anterior insula. Moreover, the common changes of disrupted sFC between sgACC and middle temporal gyrus (MTG) were found in both PPD and PPD-A patients. Interestingly, the dynamic changes of dFC between sgACC and superior temporal gyrus could differentiate PPD, PPD-A and healthy postnatal women. Taken together, our study presents the initial evidence on specifically abnormal functional dynamics of limbic, emotion regulation, and social cognition systems in the patients with PDD and PPD-A, which provides new insight into the brain dynamic dysfunction of PPD and PPD-A and may facilitate understanding neurophysiological mechanisms, diagnosis and treatment for PPD and PPD-A. Funding: This study was supported by the Chinese National Natural Science Foundation (Grant No. 82027808); Shenzhen Key Basic Research Schemes (JCYJ20200109144801736, 2019SHIBS0003); the Sichuan Science and Technology Program (Grant No. 2021YJ0186, 2019YJ0080; 21YYJC2988); the National Key Technology RD Scientific research project of Sichuan health planning committee (Grant No.20PJ078); 1.3.5 Project for disciplines of excellence, West China Hospital of Sichuan University (Grant No. 2018HXFH035); and Project of Chengdu Science and Technology Bureau (Grant No. 2019-YF05-00341- SN); and National Clinical Research Center for Geriatrics, West China Hospital of Sichuan University (Grant No. Z2018A06). Declaration of Interest: None to declare. Ethical Approval: This study was approved by the local ethics committee of West China Second University Hospital of Sichuan University and was in accordance with the latest revision of the Declaration of Helsinki.

Nonlinear analysis of functionally graded skewed and tapered wing-like plates including porosities: A bifurcation study

In the present study, nonlinear panel flutter and bifurcation behavior of functionally graded ceramic/metal wing-like tapered and skewed plates are investigated. Porosities are distributed over the cross-section of the functionally graded structure. The flutter speed, limit cycle oscillations, and bifurcation diagrams of the functionally graded plate with two types of geometrical non-uniformities being skewness and taperness are explored. Nonlinear structural model is utilized based on the virtual work principle by including the von-Karman nonlinear kinematic strain assumption. The first order shear deformation theory is employed to consider the transverse shear effect in the structural model. First-order linear piston theory is used to model the aerodynamic loading while the generalized differential quadrature method is employed to solve the governing equations of motion. Time integration of the final ordinary equations of motion is carried out using the Newmark average acceleration method. Different volume fractions are investigated to enhance the flutter instability margins and post-flutter behavior of functionally graded plates. Results demonstrate that the volume fraction and porosity coefficients have significant effects on dynamic behavior and limit cycle oscillation amplitudes.

Coned Disc Spring Compound Vertical Isolation: Testing and Modelling

ABSTRACT To improve the isolation property of conventional-coned disc spring isolation (CDSI) bearings, novel coned-disc spring compound vertical isolation (CDSCI) bearings were proposed. These combined the conventional CDSI bearings with high–damping viscoelastic (HDV) layers. Static loading tests, dynamic loading tests, and temperature dependence tests were conducted to study the mechanical performance of the CDSCI bearings. The test results indicated that HDV layers can enhance the conventional CDSI bearings’ energy-dissipation capacity effectively; the preloading displacement has a positive correlation relationship with the equivalent damping ratio and equivalent stiffness of the CDSCI bearings; and the dynamic loading amplitude has a negative correlation with the equivalent damping ratio of the CDSCI bearings, while it has a positive correlation relationship with the equivalent stiffness. As the ambient temperature increases, the equivalent damping ratio and equivalent stiffness of the CDSCI bearing decrease. Furthermore, the mechanical behavior of the CDSCI bearing was simulated using a modified Bouc–Wen model. Last, seismic responses of a typical CDSCI-isolated structure was investigated using time history analysis. Numerical results show that force responses of a structure can be reduced by CDSCI bearings effectively.

Determination of periodic response limits among multiple solutions for mechanical systems with wedge dampers

Wedge dampers are commonly used to utilize the frictional behavior in many engineering fields such as vehicle dynamics and turbo-machinery. However, the presence of non-unique contact forces in the damper interfaces creates an uncertainty that provides different dynamic response amplitudes even for the same input parameters. The maximum limits of the variability range always take the core attention in most of the damper design processes. In this paper, determination of an upper and a lower boundary among multiple steady-state solutions is presented by using a numerical approach. The method is specifically suitable for the mechanical systems with wedge dampers modeled by macro-slip frictional contact elements in the joint interfaces. In the approach proposed, a criterion that determines the periodic response boundaries according to the limit tangential force values is utilized. The method is demonstrated by illustrating several case studies on a lumped parameter system which represents a turbo-machinery application with a symmetric wedge damper pressed against two vibrating adjacent blades. A point-to-point 1D friction model with varying normal force is used in both contact sides. A parametric investigation on the variability range and response limits is performed for different damper configurations. Harmonic Balance Method with Newton's iteration scheme is used in the numerical solution of the governing equations. The results show that a large variability exists for damper geometries where a strong coupling is present between tangential and normal contact forces. The method proposed successfully captures the limits of the variability range in all cases.

Investigation of the deformation and strength properties of fouled graded macadam materials in heavy-haul railway subgrade beds

Over the course of long-term operation, the graded macadam materials used in heavy-haul railway subgrade bed surfaces become polluted to different degrees. This fouling is due to its own breakage, the intrusion of external coal debris, sand blasting, dust, and other foreign materials that accumulate on the ballast along with rainwater seepage, and the internal-structure mud-pumping. This study had the goal of determining the variation law for the deformation and strength characteristics of fouled graded macadam materials under cyclic loading. First, graded macadam materials with different fine particle contents were prepared, and a series of dynamic triaxial tests were carried out using a GCTS large-scale cyclic triaxial test system. These initial tests were conducted to determine the mechanism for the coupled effect of the fine particle content, confining pressure, and dynamic stress amplitude on a specimen’s accumulative plastic strain under cyclic loading. Using the plastic stability theory as a guideline, the dynamic deformation behaviours of specimens under different stress levels were determined, and a critical dynamic stress calculation model for specimens in the plastic creep state was established by considering the parameters of the confining pressure and fine particle content. Then, an accumulative plastic strain prediction model was established for specimens in the plastic creep state considering the stress level and fine particle content parameters, and a hardening index calculation model under cyclic loading was also established. At the same time, the physical significance of each parameter was clarified. Finally, a dynamic stress-strain relationship calculation model for fouled, graded macadam materials, which took into account the stiffness hardening under cyclic loading and stiffness degradation after fine particle intrusion, was constructed on the basis of a modified version of Iwan’s series–parallel model. The research results provide a reference for evaluating the health of existing heavy-haul railway subgrades and will be useful for designing new subgrade structures that take into account the comprehensive control principle of strength and deformation.

Influence of rubber sheet on dynamic response of machine foundations

In this study, the efficiency of employing rubber sheets to modify the dynamic response of a concrete machine foundation model of size 400 × 400 mm is explored by conducting a series of steady-state vertical vibration tests. Rubber is a low-cost energy dissipater material having high resistance to erosion which can be used in a form of sheets and simply placed beneath foundations. With a lower shear modulus than soil, it is expected to reduce the resonant frequency of a vibrating system but to increase the resonant amplitude. The former is beneficial if moving the resonant frequency far away from the machine’s operating frequency, but the latter is not desirable. To protect the rubber from UV radiation degradation, it may be helpful to embed it in soil. In this study the effects of rubber sheet thickness, vibrating system weight (dead weight), angular dynamic force and embedment depth of rubber sheet were investigated via a series of near-full-scale laboratory tests. It was found that using rubber sheets with thickness of 12 mm can increase the equivalent damping ratio of bed (up to 28%), reduce resonance frequency (by up to 13.6%), decrease transmissibility and contrary to expectations, reduce resonant amplitude (by up to 22%). Nevertheless, the efficiency of employing a rubber sheet to dynamically retrofit machine foundation depends on the angular dynamic force amplitude and dead weight of the vibrating system.

Aberrant state-related dynamic amplitude of low-frequency fluctuations of the emotion network in major depressive disorder

Major depressive disorder (MDD) is a highly prevalent mental disorder that is typically characterized by pervasive and persistent low mood. This durable emotional disturbance may represent a key aspect of the neuropathology of MDD, typified by the wide-ranging distribution of brain alterations involved in emotion processing. However, little is known about whether these alterations are represented as the state properties of dynamic amplitude of low-frequency fluctuation (dALFF) variability in the emotion network. To address this question, we investigated the time-varying intrinsic brain activity derived from resting-state functional magnetic resonance imaging (R-fMRI). Data were obtained from 50 MDD patients and 37 sex- and age-matched healthy controls; a sliding-window method was used to assess dALFF in the emotion network, and two reoccurring dALFF states throughout the entire R-fMRI scan were then identified using a k-means clustering method. The results showed that MDD patients had a significant decrease in dALFF variability in the emotion network and its three modules located in the lateral paralimbic, media posterior, and visual association regions. Altered state-wise dALFF was also observed in MDD patients. Specifically, we found that these altered dALFF measurements in the emotion network were related to scores on the Hamilton Rating Scale for Depression (HAMD) among patients with MDD. The detection and estimation of these temporal dynamic alterations could advance our knowledge about the brain mechanisms underlying emotional dysfunction in MDD.

Velocity gradient elasticity for nonlinear vibration of carbon nanotube resonators

In this study, for the first time, we investigate the nonlocality superimposed to the size effects on the nonlinear dynamics of an electrically actuated single-walled carbon-nanotube-based resonator. We undertake two models to capture the nanostructure nonlocal size effects: the strain and the velocity gradient theories. We use a reduced-order model based on the differential quadrature method (DQM) to discretize the governing nonlinear equation of motion and acquire a discretized-parameter nonlinear model of the system. The structural nonlinear behavior of the system assuming both strain and velocity gradient theories is investigated using the discretized model. The results suggest that nonlocal and size effects should not be neglected because they improve the prediction of corresponding dynamic amplitudes and, most importantly, the critical resonant frequencies of such nanoresonators. Neglecting these effects may impose a considerable source of error, which can be amended using more accurate modeling techniques.

Dynamic Characteristics of Saturated Soft Clay under Constant Confining Pressure Cyclic Loading

The research on the dynamic characteristics of soft clay under cyclic loading has high value. This paper takes Ningbo saturated soft clay as the research object and uses the GCTS true triaxial test system to analyze the effects of consolidated confining pressure and cyclic deviator stress on the axial cumulative strain. The experimental results found that when the number of vibrations and the cyclic stress ratio are the same, the axial cumulative plastic strain increases with the increase of the consolidation confining pressure. When the dynamic stress amplitude is the same, the axial cumulative strain decreases with the increase of the consolidation confining pressure. Under different confining pressures, as the number of vibrations increases, the cumulative axial strain increases. The development law of axial cumulative strain under different cyclic stress ratios is inconsistent, and there is a critical cyclic stress ratio. The experimental results provide a certain reference for engineering seismic design.

Shared and specific dynamics of brain segregation and integration in bipolar disorder and major depressive disorder: A resting-state functional magnetic resonance imaging study

BackgroundWhen bipolar disorder (BD) presents as the depressive state, it is often misdiagnosed as major depressive disorder (MDD). However, few studies have focused on dynamic differences in local brain activity and connectivity between BD and MDD. Therefore, the present study explored shared and specific patterns of abnormal dynamic brain segregation and integration in BD and MDD patients. MethodsBD Patients (n = 106), MDD patients (n = 114), and 130 healthy controls (HCs) underwent resting state functional magnetic resonance imaging (fMRI). We first used a sliding window analysis to evaluate the dynamic amplitude of low-frequency fluctuations (dALFF) and, based on the altered dALFF, further analyzed the dynamic functional connectivity (dFC) using a seed-based approach. ResultsBoth the BD and MDD groups showed decreased temporal variability of the dALFF (less dynamic segregation) in the bilateral posterior cingulate cortex (PCC)/precuneus compared with the HCs. The MDD group showed increased temporal variability of the dALFF (more dynamic segregation) in the left putamen compared with the controls, but there was no significant difference between the BD and HCs. The dFC analysis also showed that both the BD and MDD groups had reduced dFC (less dynamic integration) between the bilateral PCC/ precuneus and the left inferior parietal lobule compared with the HCs. LimitationsThis study was cross-sectional and did not examine data from remitted BD and MDD patients. ConclusionOur findings indicated disrupted dynamic balance between segregation and integration within the default mode network in both BD and MDD. Moreover, we found MDD-specific abnormal brain dynamics in the putamen.