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Political culture and participation in urban China
\"This book discusses one of the most noticeable and significant transformations in China over the past three decades is the rapid and massive urbanization of the country, which has brought shifts in political culture of Chinese urbanites. This book is a systematic and empirical study of political culture in urban China. The book covers various aspects of political culture such as political regime support, political interest, democratic values, political trust, and environmental attitudes and sub-political culture of Chinese urban Christians. This book will be of immense value to urban scholars, sinologists, and those wishing to get a closer look at the issues that affect the political future of a rising world power.\"-- Provided by publisher.
Book
Alterations of local functional connectivity in lifespan: A resting‐state fMRI study
Introduction As aging attracted attention globally, revealing changes in brain function across the lifespan was largely concerned. In this study, we aimed to reveal the changes of functional networks of the brain (via local functional connectivity, local FC) in lifespan and explore the mechanism underlying them. Materials and Methods A total of 523 healthy participants (258 males and 265 females) aged 18–88 years from part of the Cambridge Center for Ageing and Neuroscience (CamCAN) were involved in this study. Next, two data‐driven measures of local FC, local functional connectivity density (lFCD) and four‐dimensional spatial‐temporal consistency of local neural activity (FOCA), were calculated, and then, general linear models were used to assess the changes of them in lifespan. Results Local functional connectivity (lFCD and FOCA) within visual networks (VN), sensorimotor network (SMN), and default mode network (DMN) decreased across the lifespan, while within basal ganglia network (BGN), local connectivity was increased across the lifespan. And, the fluid intelligence decreased within BGN while increased within VN, SMN, and DMN. Conclusion These results might suggest that the decline of executive control and intrinsic cognitive ability in the aging population was related to the decline of functional connectivity in VN, SMN, and DMN. Meanwhile, BGN might play a regulatory role in the aging process to compensate for the dysfunction of other functional systems. Our findings may provide important neuroimaging evidence for exploring the brain functional mechanism in lifespan. We used local functional connectivity (FCD and FOCA) to explore changes across the lifespan and behavior scores (fluid intelligence and response time in response time tasks). Our findings may provide important neuroimaging evidence for exploring the brain functional connectivity mechanism across the lifespan.
Journal Article
On Local Activity and Edge of Chaos in a NaMLab Memristor
Local activity is the capability of a system to amplify infinitesimal fluctuations in energy. Complex phenomena, including the generation of action potentials in neuronal axon membranes, may never emerge in an open system unless some of its constitutive elements operate in a locally active regime. As a result, the recent discovery of solid-state volatile memory devices, which, biased through appropriate DC sources, may enter a local activity domain, and, most importantly, the associated stable yet excitable sub-domain, referred to as edge of chaos, which is where the seed of complexity is actually planted, is of great appeal to the neuromorphic engineering community. This paper applies fundamentals from the theory of local activity to an accurate model of a niobium oxide volatile resistance switching memory to derive the conditions necessary to bias the device in the local activity regime. This allows to partition the entire design parameter space into three domains, where the threshold switch is locally passive (LP), locally active but unstable, and both locally active and stable, respectively. The final part of the article is devoted to point out the extent by which the response of the volatile memristor to quasi-static excitations may differ from its dynamics under DC stress. Reporting experimental measurements, which validate the theoretical predictions, this work clearly demonstrates how invaluable is non-linear system theory for the acquirement of a comprehensive picture of the dynamics of highly non-linear devices, which is an essential prerequisite for a conscious and systematic approach to the design of robust neuromorphic electronics. Given that, as recently proved, the potassium and sodium ion channels in biological axon membranes are locally active memristors, the physical realization of novel artificial neural networks, capable to reproduce the functionalities of the human brain more closely than state-of-the-art purely CMOS hardware architectures, should not leave aside the adoption of resistance switching memories, which, under the appropriate provision of energy, are capable to amplify the small signal, such as the niobium dioxide micro-scale device from NaMLab, chosen as object of theoretical and experimental study in this work.
Journal Article
A S-type bistable locally active memristor model and its analog implementation in an oscillator circuit
In this paper, a S-type memristor with tangent nonlinearity is proposed. The introduced memristor can generate two kinds of stable pinched hysteresis loops with initial conditions from two flanks of the initial critical point. The power-off plot verifies that the memristor is nonvolatile, and the DC
V
-
I
plot shows that the memristor is locally active with the locally active region symmetrical about the origin. The equivalent circuit of the memristor, derived by small-signal analysis method, is used to study the dynamics near the operating point in the locally active region. Owing to the bistable and locally active properties and S-type DC
V
-
I
curve, this memristor is called S-type BLAM for short. Then, a new Wien-bridge oscillator circuit is designed by substituting one of its resistances with S-type BLAM. It finds that the circuit system can produce chaotic oscillation and complex dynamic behavior, which is further confirmed by analog circuit experiment.
Journal Article
Age-related functional brain changes in young children
Brain function and structure change significantly during the toddler and preschool years. However, most studies focus on older or younger children, so the specific nature of these changes is unclear. In the present study, we analyzed 77 functional magnetic resonance imaging datasets from 44 children aged 2–6 years. We extracted measures of both local (amplitude of low frequency fluctuation and regional homogeneity) and global (eigenvector centrality mapping) activity and connectivity, and examined their relationships with age using robust linear correlation analysis and strict control for head motion. Brain areas within the default mode network and the frontoparietal network, such as the middle frontal gyrus, the inferior parietal lobule and the posterior cingulate cortex, showed increases in local and global functional features with age. Several brain areas such as the superior parietal lobule and superior temporal gyrus presented opposite development trajectories of local and global functional features, suggesting a shifting connectivity framework in early childhood. This development of functional connectivity in early childhood likely underlies major advances in cognitive abilities, including language and development of theory of mind. These findings provide important insight into the development patterns of brain function during the preschool years, and lay the foundation for future studies of altered brain development in young children with brain disorders or injury.
•77 fMRI datasets from 44 children aged 2–6 years were collected and analyzed.•Robust correlation analysis was used to test age-related changes in functional metrics.•Nodes in the default mode and frontoparietal networks had increasing connectivity.•The superior temporal lobe had a shift from local-to-global connectivity.
Journal Article
Assessing the coupling between local neural activity and global connectivity fluctuations: Application to human intracranial electroencephalography during a cognitive task
Cognitive‐relevant information is processed by different brain areas that cooperate to eventually produce a response. The relationship between local activity and global brain states during such processes, however, remains for the most part unexplored. To address this question, we designed a simple face‐recognition task performed in patients with drug‐resistant epilepsy and monitored with intracranial electroencephalography (EEG). Based on our observations, we developed a novel analytical framework (named “local–global” framework) to statistically correlate the brain activity in every recorded gray‐matter region with the widespread connectivity fluctuations as proxy to identify concurrent local activations and global brain phenomena that may plausibly reflect a common functional network during cognition. The application of the local–global framework to the data from three subjects showed that similar connectivity fluctuations found across patients were mainly coupled to the local activity of brain areas involved in face information processing. In particular, our findings provide preliminary evidence that the reported global measures might be a novel signature of functional brain activity reorganization when a stimulus is processed in a task context regardless of the specific recorded areas. Cognitive‐relevant information is processed by different brain areas that cooperate to eventually produce a response. Here, we develop a novel analytical framework (named “local–global” framework) to statistically correlate the signal power in every recorded gray‐matter region (intracranial electroencephalography) with the widespread connectivity fluctuations as proxy to identify concurrent local and global activity that may plausibly reflect a common functional network during cognition. The application of the local–global framework to the data from three subjects with different recorded areas showed similar connectivity fluctuations, which were mainly coupled to local activity of brain areas involved in the task.
Journal Article
Regional Features of the 20–30 Day Periodic Behavior in the Southern Hemisphere Summer Circulation
The Southern Hemispheric storm tracks exhibit a robust intraseasonal periodicity of 20–30 days as the leading mode of zonal‐mean eddy kinetic energy. To what extent this hemispheric‐scale mode of variability translates to smaller scales remains debated. This work studies the regional features of Southern Hemisphere storm tracks through a filtered variance analysis of local finite‐amplitude wave activity. While the synoptic variance is zonally elongated over the storm track, we find a strong enhancement of intraseasonal variability within the South Pacific. With a minimum strength of the storm track, this region is marked with 20–30 day periodic behavior of local wave activity and precipitation and is driven by enhanced variability of low‐level eddy heat flux on the same timescale. The local nature of 20–30 day periodicity offers a potential source of subseasonal to seasonal predictability for weather analysts and forecasters. Plain Language Summary Storms and precipitations in the Southern Hemisphere overall experience a regular pulsing every 20–30 days that we call Baroclinic Annular Mode. We don’t understand what physical process drives this regular pulsing but we hypothesize that a regional analysis would be helpful to investigate this open question. Further, if such periodic pulsing of storms and precipitations can be identified within a specific region, it would have important implications for understanding and predicting the medium‐range weather system, especially for extreme events. In this work, we pin down the regional features of the 20–30 day pulsing by demonstrating the spatial distribution of storms and precipitations in terms of their variance and periodicity within different time scales. We found that while the short‐time storm activity (2–7 days) exhibits a similar strength across the Southern Ocean, the storm activity within the time scale of Baroclinic Annular Mode (20–30 days) exhibits a localized periodicity concentrated in the South Pacific. The local nature of this 20–30 day periodicity indicates a potential utility for weather analysts and forecasters. Key Points The hemispheric‐scale mode of variability in extratropical eddy activity translates its 20–30 day periodicity to smaller spatial scales A strong enhancement of intraseasonal variability and local periodic behavior is identified within the South Pacific The local nature of 20–30 day periodicity offers a potential source of intraseasonal predictability for weather analysts and forecasters
Journal Article
Global dynamics of Chua Corsage Memristor circuit family: fixed-point loci, Hopf bifurcation, and coexisting dynamic attractors
This paper presents an in-depth and rigorous mathematical analysis of a family of nonlinear dynamical circuits whose only nonlinear component is a
Chua Corsage Memristor (CCM)
characterized by an explicit seven-segment piecewise-linear equation. When connected across an external circuit powered by a DC battery, or a sinusoidal voltage source, the resulting circuits are shown to exhibit four asymptotically stable
equilibrium points
, a unique stable
limit cycle
spawn from a supercritical
Hopf bifurcation
along with three static attractors, four
coexisting dynamic attractors
of an associated
non-autonomous nonlinear differential equation,
and four corresponding
coexisting
pinched hysteresis loops. The
basin of attractions
of the above static and dynamic attractors is derived numerically via
global nonlinear analysis.
When driven by a battery, the resulting
CCM circuit
exhibits a
contiguous fixed-point loci
, along with its
DC V–I curve
described analytically by two explicit
parametric
equations. We also proved the
fundamental feature of the
edge of chaos
property; namely,
it is possible to destabilize a stable circuit
(i.e., without oscillation) and make it
oscillate
, by merely adding a
passive
circuit element, namely
L
>
0
. The
CCM circuit family
is one of the few known example of a strongly nonlinear dynamical system that is endowed with numerous coexisting static and dynamic attractors that can be studied both experimentally, and mathematically, via exact formulas.
Journal Article